Fertiliser production, marketing and use - HANDBOOK OF SOLID … · 2019. 11. 25. · This Handbook...

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HANDBOOKOFSOLIDFERTILISERBLENDING-CodeofGoodPracticeforQuality 1

EUROPEANFERTILIZERBLENDERSASSOCIATION

HANDBOOKOFSOLID

FERTILISERBLENDING

CodeofGoodPracticeforQualityThirdEdition

EditedbyJoGilbertsonandEstelleVallin

www.european-blenders.org

89rueMagenta53000LAVAL,France

ThishandbookisalsoavailableinFrenchorGerman

CONTENTS

1. INTRODUCTION…………………………………………………………………………………….....……………………….4 1.1 BlendedFertilisers.............................................................................................................4

1.2 FertiliserBlenders..............................................................................................................4

1.3 ServicesandSoilAnalysis..................................................................................................5

2. DEFINITIONS.................................................................................................................................63. RAWMATERIALS..........................................................................................................................8

3.1 ChemicalProperties...........................................................................................................9

3.1.1 Compatibility.......................................................................................................93.2 PhysicalProperties...........................................................................................................11

3.2.1 ParticleSize.......................................................................................................113.2.2 Density..............................................................................................................123.2.3 Shape.................................................................................................................133.2.4 ParticleHardness..............................................................................................133.2.5 DustContent.....................................................................................................133.2.6 FlowRate..........................................................................................................13

3.3 Storage.............................................................................................................................13

3.3.1 MoisturePick-up...............................................................................................153.3.2 Contamination..................................................................................................16

3.4 Screening..........................................................................................................................17

3.5 SamplingandTesting.......................................................................................................17

3.6 MicronutrientsandConditioningAgents.......................................................................17

3.6.1 Micronutrients..................................................................................................173.6.2 ConditioningAgents.........................................................................................17

4. BLENDINGEQUIPMENT.............................................................................................................184.1 Selection...........................................................................................................................18

4.1.1 Weighing...........................................................................................................184.1.2 VolumetricFeeding..........................................................................................194.1.3 Mixers................................................................................................................204.1.4 LoadingEquipment...........................................................................................20

4.2 Testing/Calibration..........................................................................................................20

4.3 Operations.......................................................................................................................20

5. SEGREGATION............................................................................................................................215.1 FlowSegregation.............................................................................................................21

5.2 TransportSegregation.....................................................................................................25

5.3 SpreadingSegregation.....................................................................................................25

5.4 EFBAQualityRecommendations....................................................................................30

6. SAFETYCLASSIFICATION–LABELLING-DISTRIBUTION...........................................................316.1 LabellingandMarkingofFertilisers................................................................................31

6.2 LabellingandClassificationofHazardousSubstancesandMixtures…………………………32

6.3 SafetyDataSheets…………………………………………………………………………………………………..34

7. QUALITYCONTROL.....................................................................................................................36 7.1 RawMaterials..................................................................................................................36

7.2 FinishedProducts.............................................................................................................36

8. SAMPLINGANDANALYSIS.........................................................................................................378.1 Sampling...........................................................................................................................37

8.1.1 SamplingQuantity............................................................................................388.1.2 SamplingEquipment........................................................................................398.1.3 SampleDivider..................................................................................................40

8.2 ChemicalAnalysis............................................................................................................40

8.3 PhysicalTests...................................................................................................................40

8.3.1 TestMethodforSieveAnalysis........................................................................418.3.2 TestMethodforLooseBulkDensity................................................................428.3.3 TestMethodforAngleofRepose………………………………………………………………43

8.4 Examples..........................................................................................................................44

9. FORMULATION...........................................................................................................................4710. REFERENCES................................................................................................................................48

1. INTRODUCTION

ThisHandbookof SolidFertiliserBlendinghasbeenpreparedby theEuropeanFertilizerBlendersAssociation(EFBA)tohelpmembersachievetheirtargets:

1 Theidentificationofcropneeds,inconsultationwithfarmercustomers.

2 Theproductionofhighqualityblendedfertilisersfortheagriculturalmarkettosatisfytheseneeds.

3 Theaccuratedeliveryandspreadingofthesefertilisers.

Thishandbooksetsoutadvicewhich,iffollowed,shouldleadtoimprovedqualityoffinishedproducts,andawideracceptabilityofblendedfertilisersintheEuropeanmarketplace.

1.1 BLENDEDFERTILISERS

Theblendingofsolidgranularmaterialstoproduceawiderangeofcompoundfertilisershasbeensuccessfullypractisedforover40years.Insomecountriesblendsformbyfarthemajorproportionofcompoundfertiliserssold.

Blendedfertilisershavethreemainadvantagesovercomplexfertilisers. Thefirstisthatofversatility,thesecondisasimplematterofeconomicsandthethirdisabetterprotectionoftheenvironment.Usingalimitednumberofbasematerials,analmostinfiniterangeofcompoundscanbeproduced.These can be specificallymatched to local soil conditions and plant needs, thus avoiding excessnutrientswhichmayentertheenvironment.Multiplehandlingof thebasicrawmaterialssuchasphosphaterock, isavoidedbymaintaining theprimaryproductionprocessesat thesourceof thenutrients. Thematerialswhichthenneedtobetransportedtotheagriculturalareascontainthehighestpossibleamountsofnutrients,thusreducingoverallcosts.

Themaindisadvantageofblended fertilisers, incomparisonwithcomplex fertilisers, is theriskofsegregationofthecomponentsduringhandlingorspreading. However,thisbookshowshowtoavoidsegregation.

1.2 FERTILISERBLENDERS

Blenders,incommonwithotherfertiliserproducers,haveaclearresponsibilitytoensurethattheirproductsareofhighquality. Rawmaterialproducershaveaclearresponsibilitytoensurethatthematerialstheysupplytotheblendersarealsoofaconsistentlyhighqualityandconformtotheagreedspecifications. Thatistosay,theysupplymaterialsofguaranteedanalysisintermsoftheirnutrientcontentsandphysicalproperties.

Theblenderisresponsibleforhischoiceofequipmentandforspecifyingthequalityofrawmaterialshe ispurchasing. Inadditionhehasaresponsibilitytocheckthequalityoftherawmaterialshereceivesandtomonitorhisproductionatallstagestoensurefinishedproductsareofthehighestquality.

Fertiliserblendersarehandlingmaterialswhich,ifmismatchedormishandled,canresultinverypoorqualityfinishedfertiliserwhichwillnottransport,storeorspreadsatisfactorily.

There isacleareconomicbenefit tosuppliersandusersalike in improvingthequalityofblendedfertilisers. Poorqualityproductscanhaveseriousconsequences,bothlegalandfinancial.

TheSolidFertiliserBlendingHandbookcontainspracticaladvicetohelpmanufacturersachievehighqualityblends.

1.3 SERVICESANDSOILANALYSIS

Whilsttheblender’sresponsibilityfortheproducteffectivelyfinisheswithitsdeliverytofarm,theresponsibilitytoprovideascompleteaserviceaspossibledoesnot. Indeed,withmodernsystemsofcustomblending,theresponsibilitystartsandfinishesonthefarm.

Blending can be considered to be a complete system provided for the farmer, startingwith soilsampling,analysingitsnutrientrequirements,andfinishingwiththeaccuratespreadingofthecorrectblendofnutrients.

2. DEFINITIONS

Throughoutthishandbookthegeneraltermsblendandblendingareusedtodenotetheproductandtheprocessofmixinggranularmaterials. Blendedfertilisersmaybesuppliedtofarmersinbagsorin bulk. The term bulk-blend is reserved for situations where the blend is handled (stored,transported)inbulkratherthaninbags.

Blendsdonotnecessarilyconsistofmixturesofstraightfertilisersorsinglecompounds. Ablendoftwoorthreegranularcomplexfertiliserswillstillbeablendedfertiliser.

Anumberofotherspecifictermsareusedandthesearedefinedasfollows:

Blendedfertiliser:Fertiliserobtainedbydryphysicalblendingofvariousrawfertilisers,withoutanychemicalreaction.

Complexfertiliser:Compoundfertiliserobtainedbychemicalreaction,byliquidsolutionor,inthesolidstate,bygranulationandhavingadeclarablecontentofatleasttwoofthemajornutrients.

Note 1: For the solid granules, each particle contains all the nutrients approximately in theirdeclarablecontent.

Note2:SomeCompaniesusetheterm“uniform”tomeanacomplexfertiliserandtoindicatetheproductisnotablend.

Compoundfertiliser:Fertiliserhavingadeclarablecontentofatleasttwoofthenutrientsnitrogen,phosphorusandpotassium,obtainedchemicallyorbyblending,orboth.

Note:With thesedefinitions,monoanddi-ammoniumphosphatesandpotassiumnitratearenot“straights”butareNPandNKcomplexfertilisersrespectively.

d50 (Meanparticlesize):Thatsizesuchthathalftheparticles,bymass,arelargerthanthatsizeandhalfaresmaller.

Granularfertiliser:Solidfertiliserformedintoparticlesofapredeterminedmeansizebygranulation.

Note: Insomecountries,thistermisoften(wrongly)usedtomeancomplexfertilisers.

Granulation:Techniqueusingprocessessuchasagglomeration,accretion,compaction,tomodifytheparticlesize.

Granulometricspreadindex(GSI):Measureofthespreadofparticlesizesandameansofexpressingthegranulometricspread.

Increment:Representativequantityofmaterialtakenfromasamplingunit.

Lot: Totalquantityofmaterial, assumed tohave the samecharacteristics, tobe sampledusingaparticularsamplingplan.

Meanparticlesize(d50):Thatsizesuchthathalftheparticles,bymass,arelargerthanthatsizeandhalfaresmaller.

Particlesize:Dimensionwhichcorrespondstothesmallestsieveaperturesizethroughwhichaparticlewillpassifpresentedinthemostfavourableattitude.

Particlesizeanalysisbysieving:Divisionofasamplebysievingintosizefractions.

Rawmaterial:Solid,granularmaterialusedasacomponentinablendedfertiliser.

Note: Some of these materials are not the basic source materials which provide the nitrogen,phosphateandpotash. Inthesecases,theyareoftenknownasintermediatesorpre-mix.

Segregation:Differentialmovementofparticleswithinamixtureduetodifferencesintheirsize,shapeordensity,resultingintheirseparation.

Sieving:Processofseparatingamixtureofparticlesaccordingtotheirsizesbyoneormoresieves.

Sizeguidenumber(SGN):100timesthed50measuredinmillimetres

Spreadingwidth:Distancebetweentheextremeleftandrightpointswherethefertiliserarrivesontheground.

Straight fertiliser: Qualification generally given to a nitrogenous, phosphatic or potassic fertiliserhavingadeclarablecontentofonlyoneoftheplantnutrientsnitrogen,phosphorusorpotassium.

Note: It is possible for a straight fertiliser to be a blend. For example a mixture of granularammoniumnitrateandgranularammoniumsulphatewouldbeastraightnitrogenfertiliser.

Testsieving:Sievingwithoneormoretestsieves.

Workingwidth:Distancebetweeneachpassage(generallybetween12and48m)whenspreadingfertilisers.

Definitions of other technical termsmay be found in EN 12944 Fertilisers and LimingMaterials,Vocabulary,Part1[8].

3. RAWMATERIALS

Thequalityofthefinishedproductdependsalmostentirelyontherawmaterials.Goodblendingstartswithgoodrawmaterials. Itisnotrealistictoexpecttomakegoodqualityblendedfertilisersfrompoorrawmaterials. Thespecification,purchaseandcheckingofrawmaterialsmustbethefirstpriorityoftheblender.

Every rawmaterial should be bought to as tight a specification as possible. Deliveriesmust becheckedregularly,preferablybyindependentinspectors,toensureconsistentquality.Allsamplingandtestingshouldbecarriedoutusingmethodsagreedbetweensupplierandpurchaser,basedeitheronNationalorEuropeanlegislationoronacceptedInternationalStandards(CEN,ISOetc.). Moreinformationaboutsamplingwillbefoundinsection8.

Whilstmany fertiliser rawmaterialsmaybeconsideredtobecommodities, rather thanspecialitychemicals, theopportunisticpurchaseof spotconsignmentsofdoubtfuloriginandquality isNOTRECOMMENDED.Norawmaterialshouldbepurchasedwithoutanagreedcontractualspecificationcovering,asaminimum,theregistrationtoREACH,thechemicalanalysisandtheparticlesizedetails.

3.1 CHEMICALPROPERTIES

Thenutrientcontentofeachrawmaterialusedmustbeknowninordertoprepareformulationsfor the different compounds required. Raw material suppliers should be asked to supplycertificatesofanalysisforeachlargeconsignment. Whereconsignmentsdiffermarkedlytheyshouldbestoredseparatelyandtheformulationsadjustedtotakeaccountofthetrueanalysisfigures(seeChapter9)

Thewatercontentofeachrawmaterialusedmustbeknowninordertoensurecompatibilitybetweenrawmaterials.

In all cases it is advisable tomakeoccasional randomchecksby arranging for representativesamplestobetakenbyindependentinspectors. Thesesamplesshouldbeanalysedassoonaspossibleandbeforetheconsignmentisused.

3.1.1 Compatibility

Somerawmaterialsarenotcompatiblewithothersandblendscontainingsuchmixtureswillbeofverypoorquality. Thecompatibilitydataarepresentedinthetablebelowinthreecategories(Figure1).

FurtherinformationregardingcompatibilitymaybefoundinReference13

Figure1.COMPATIBILITYOFVARIOUSSOLIDINORGANICFERTILIZERS

iumNitrate

CalciumAmmon

iumNitrate

Calciumnitrate(fe

rtilizerg

lphatenitrate

PotassiumNitrate/S

odiumnitrate

lphate

RockPho

sphate

Partiallyacidu

latedrockpho

sphate

Single/Trip

hosphate

oammon

iumpho

sphate

iumpho

sphate

tassiumpho

sphate

Potassiumchloride

Potassiumsu

lphate/m

sulphate(kieserite)

,NP,NK(ANbased

,NP,NK(Ureabased)

Limestone

/dolom

ite/calcium

sulphate/Calcium

Sulphu

r(elem

ental)

AmmoniumNitrate

1 2 3 NC1 4 4 5 5

CalciumAmmoniumNitrate 6 2 2 NC1 7 5 5 NC

Calciumnitrate(fertilizergrade) 1

6 8 8 8 8 8 8 8 8 8 9 8 8 8

Ammoniumsulphatenitrate 2 2 8 2 NC1 10 4 7 5 5 NC

Potassium Nitrate/ Sodiumnitrate

8 2 11 12 13 NC

2Ammoniumsulphate 3

2 8 11 5

Urea NC1

NC1 8 NC

1 14 15 16 NC1

RockPhosphate

Partially acidulated rockphosphate 4

4 14 17

Single/Triplesuperphosphate 4

7 8 7 15 17 4 14 17

Monoammoniumphosphate

Diammoniumphosphate

8 17 17

Monopotassiumphosphate

Potassiumchloride 5

5 8 5 16 5

Potassium sulphate/magnesiumsulphate(kieserite)

NPK,NP,NK(ANbased) 5 5 8 5 12 5 NC1 4 5 NC

NPK,NP,NK(Ureabased) NC1

NC1 8 NC

1 13 14 NC1

Limestone/dolomite/calciumsulphate/Calciumcarbonate

Sulphur(elemental) NC2

NC2 8 NC

2NC2 NC

Compatible

Limitedcompatibilitylinked

toqualityissues

Limitedcompatibilityrelated

tosafetyorregulatoryissues

NC NotCompatible

DISCLAIMER:ThisdocumenthasbeenproducedforthebenefitofthemembersofFertilizersEurope.Theinformationandguidanceprovidedinthisdocumentisgiveningoodfaith.FertilizersEurope,itsmembers,consultantsandstaffacceptnoliabilityforanylossordamagearisingfromtheuseofthisguidance.

Notesforthenumbersintheboxesinthecompatibilitytable

LimitedCompatibility 1. Duetothehygroscopicbehaviourofbothproducts,thetypeofstabilisationofthe

ammoniumnitrategradecouldinfluencestorageproperties. 2. Considerthesafetyimplicationsregardingdetonabilityoftheblend(AN/ASmixtures)and

legislativeimplications. 3. Considerthesafetyimplicationsregardingdetonabilityoftheblend(AN/ASmixtures),

impactoffreeacidandorganicimpurities,ifpresent,andlegislativeimplications. 4. IffreeacidispresentitcouldcauseveryslowdecompositionofAN,affecting,forexample,

packaging. 5. Considerthepossibilityofself-sustainingdecompositionandtheoveralllevelofoilcoating. 6. Duetothehygroscopicbehaviourofbothproducts,thetypeofstabilisationofthe

ammoniumnitratebasedfertilizercouldinfluencethestorageproperties. 7. ConsiderthemoisturecontentoftheSSP/TSP. 8. Considertherelativehumidityduringblending. 9. Riskofformationofgypsum. 10. Noexperiencebutthiscanbeexpectedtobecompatible.Confirmbytestand/oranalysis. 11. ConsiderimpuritiesinASandthedropinthecriticalrelativehumidityoftheblend. 12. Considerthelikelyimpactofadditionalnitrate. 13. Considerthepossibilityofammoniumphosphate/potassiumnitratereactionwithureaand

relativehumidityduringblendingtoavoidcaking. 14. Iffreeacidpresent,thereisapossibilityofhydrolysisofureagivingammoniaandcarbon

dioxide. 15. Formationofverystickyureaphosphate. 16. Potentialcakingproblemduetomoisture. 17. Iffreeacidispresent,considertheriskofareactione.g.neutralisationwithammoniaand

acidattackwithcarbonates.

NotCompatible

NC1. Mixturewillquicklybecomewetandabsorbmoistureresultinginformationofliquidor slurry.Therecouldalsobesafetyimplications. NC2. Sulphuriscombustibleandcanreactwithnitratese.g.AN,KNO3andNaNO3.

Fromthechart,itisclearthatureaandammoniumnitrateshouldneverbeusedtogetherasthemixturewillquicklybecomewetandabsorbmoisture. Blendscontainingureaandsingleortriplesuperphosphatemayalsobecomestickyandcake. Suchblendsshouldneverbebagged. Mixtures of di-ammonium phosphate and superphosphates should be avoided as chemicalreactionsmaytakeplacewhichcanleadtocakingorchangesinthesolubilityofthephosphate.

Forreasonsofsafety,itisveryimportanttoavoidblendingammoniumnitrateorrawmaterialscontainingammoniumnitratewithanyorganicmaterials.

3.2 PHYSICALPROPERTIES

Themost important physical property - as far as blending is concerned - is the particle sizedistribution.

Theparticlesizedistributionmustbeknowninsomedetailandthespecificationmustincludeafulldescriptionofthisproperty. Attheveryleast,themeanparticlesize(asmeasuredbythed50)mustbespecified. Ideally,thespecificationshouldincludeameasureofthegranulometricspread index (GSI) and shouldalso includemaximumvalues for theamountsofoversize (forexample>5mm)andfines(forexample<1mm).

Theshapeandthedensityofparticlescouldhaveaninfluenceonthebehaviourofthefertiliserduringspreading.

Otherphysicalcharacteristics tobespecifiedmust include“freeflowing”and“dust free”andpossiblyhardnessandimpactresistance. However,thesepropertiesaremuchmoredifficulttoassessusingstandardtestmethods. Morerealistically,itisbettertospecifythatsuitableanti-cakingand/oranti-dust treatment isappliedtotherawmaterialandthat itshouldnotbreakdownduringhandling.

In all cases it is advisable tomakeoccasional randomchecksby arranging for representativesamples tobe taken and assessedby independent inspectors. It is also recommended thatsamplesbetakenduringthedeliveryandtestedforsizedistributionattheblendingplant.SeeSection5.4)

3.2.1 ParticleSize

Thekeyfactorinproducingqualityblendsisthesizecompatibilityoftherawmaterials. Unlessalltheingredientsarewellmatched,segregationwilltakeplaceeverytimetheblendishandledinbulk. Thiswill leadtounevennessofchemicalanalysisandpossibly,unevenspreadingofnutrientsonthecrops.

Theparticlesizedistributioncanbeexpressedinanumberofwaysbutallrelyonasieveanalysisofthematerial. Itisessentialthereforethatblendersshouldhavethefacilitytocarryoutafullsieveanalysisoftheirrawmaterials(seechapter8).

Anumberofsimplefieldtestdevicesareavailablebutthesearelimitedintheirabilitytomeasureparticlesizedistributionadequately. Theyarehowever,veryusefultocarryoutspotchecksonrawmaterialsbeingfedtotheblender.

The official method of test sieving is fully described in European Standard EN 1235 andAmendment A1 [3]. A number of numerical parametersmay be calculated from the sieveanalysis. Theseincludethemeanparticlesize(d50)andgranulometricspreadindex(GSI). Inviewoftheimportanceofsizedistribution,fulldescriptionsoftheseparametersandtheuseofthevarioussystemsaredescribedbelow.

However,forthebestresults,itisrecommendedthatafullsizedistributioncurveisplottedforallrawmaterialsamplestested. Adescriptionofthetestsievingtechniqueisgiveninparagraph8.3.1. Sizedistributioncurvescanreadilybesuperimposedtogiveaquickcomparisonandanindicationofcompatibility.

Themeanparticlesize(d50)isdeterminedusingthefollowingequation:(1)

( )( ) ( )nn

ccczd 50 1

Where:

1 znisthenominalsievemeshinmmforwhichthecumulativeundersizeisnearesttobutbelow50%bymass

2 zn+1isthenominalsievemeshinmmforwhichthecumulativeundersizeisnearesttobutabove50%bymass

3 cnisthecumulativepercentageundersizeforsieven

4 cn+1isthecumulativepercentageundersizeforsieven+1

NOTE:d84andd16arecalculatedinthesamewaybysubstituting84and16respectivelyfor50inequation(1)above.

Anexcellentmeasureof thespreadofparticlessizescanbeobtainedusing thewholeof thelinearpart(betweend84andd16)ofthedistributioncurveobtainedfromthesieveanalysis. Thevaluesofd84andd16maybefounddirectlyfromthegraphorbycalculation. Thespreadisthedifferencebetweenthetwo:

1684 dd -=D

An important value, known as the Granulometric Spread Index (GSI), is derived from thefollowingformula:

100 d 2 50

1684 ddGSI -=

3.2.2 BulkDensity

ThebulkdensityofthefertilisermaybemeasuredinaccordancewithEN1236(Loosedensity)[4]orEN1237(tappeddensity)[5]. Thegeneralprincipleistoweighthecontentsofacylinderofaknownvolume. Forthetappeddensity,thecylinderissubjecttovibrationsandcompactionoccurs. Thisvalueisalwayshigherthantheloosedensity.

The density of the fertiliser can have an influence on the behaviour of the particles duringspreadingonthefield. Severesegregationmayoccur if thedensitiesareverydifferent (seesection5.3).

Generally,theloosebulkdensityoffertilisersisbetween900and1100kg/m³butextremevaluescan be between 750 and 1350 kg/m³. In practice these extreme values rarely occursimultaneously.

3.2.3 Shape

Themeasurementoftheshapeofthefertiliserparticlesisnoteasy. Generally,itisnecessarytouseimageanalysistechniques. However,themeasurementoftheangleofreposeofaheapformedbyafertiliserflowingfromafunnelcanbeausefulguidetothisparameter. ThemethodisstandardisedinEN12047[6]anddescribedinparagraph8.3.3. Anglesofreposevaryfromabout30°forthemostsphericalproductsto40°forthemostangular.

3.2.4 ParticleHardness

Duringhandlingandspreading,thefertiliserwillbesubmittedtostresseswhichcanbreaktheparticles,forexampletheimpactwiththevanesduringspreading. Thisprocessleadstotheproductionofsmallgrainswhichcausesomeproblems(segregation,caking). Forthisreasonthe particles should be of a sufficient hardness. Unfortunately, the test methods are notstandardised because of the variability of the measurement and the evolution of theseparameterswithtime. Iftheparticlehardnessislow,thefertilisermaycontaintoomanysmallparticlesandthusmaynolongermeetthequalitycriteria(seesection5.4).

3.2.5 DustContent

Somefertilisershavethetendencytoproducelargeamountsofdust. Thiscancauseproblemsintheneighbourhoodoftheplantandaccentuatestheriskofcaking. Thereisnostandardtestmethodbutwithsomeexperiencetherawmaterialspresentingthisproblemareeasilydetected.

3.2.6 FlowRate

Normally,thefertilisermustflowfreely. Ifthereisanycakingorsomereactionbetweenthecomponentsorwithmoisture,theflowabilityofthefertilisercanbereduced. Thiscanleadtoproblemsforallthehandlingoperations.

AstandardmethodforthemeasureoftheflowratehasbeendevelopedasEN13299[7]. About2kgoffertiliserisplacedinastandardfunnelwhichhasaclosedapertureof25mmdiameter. Thentheapertureisopenedandthetimefor2kgtoflowoutofthefunnelismeasured. Theapparatusiscalibratedwithdefinedglassspheres.

Table1:Commonblendingrawmaterials

Name Abbr Formula N P2O5 K2O SO3 MgO CaO

AmmoniumNitrate

AN NH4NO3 33-34,5

CalciumAmmoniumNitrate

CAN CaCO3/NH4NO3 26-28 11

AmmoniumSulphateNitrate

ASN (NH4)2SO4/NH4NO3 26 35

AmmoniumSulphate

AS (NH4)2SO4 21 60

Urea CO(NH2)2 46 Superphosphates:SingleSuperphosphateTripleSuperphosphate

SSPTSP

Ca(H2PO4)2*Ca(H2PO4)2*

18-2045-48

PotassiumChloride

MOP KCl 60-62

PotassiumSulphate

SOP K2SO4 50 45

Korn-Kali® KCl/MgSO4 40 12 6 PotassiumMagnesiumSulphate

K2SO4+MgSO4 30 42 10

AmmoniumPhosphates:Di-ammoniumPhosphateMono-ammoniumPhosphate

DAPMAP

(NH4)2HPO4

NH4H2PO4

46-4852-53

CalciumCarbonate

CaCO3 52

CompactedDolomite

CaCO3-MgCO3 20 30

MagnesiumCarbonate

MgCO3 10 40

Kieserite MgSO4 50 25-28

3.3 STORAGE

Rawmaterialstoragemustbearrangedtoavoid:

1 segregationwithinthematerials

2 crosscontamination

3 deteriorationofthephysicalquality.

Storagemustbearrangedtoensureadequateidentificationoftherawmaterials.

Therecommendedtypeofstorageisthehorizontaloropenbinlayout. Ideallythebinshouldbefedfroma conveyorbelt systemwith thedischarge fittedwithananti-segregation systemsuchas aspinnerorflowsplitter(Figure5).

TheEuropeanFertiliserManufacturers'Association(EFMA)haspublisheddetailedguidanceonthesafestorageoffertilisers.[12]

3.3.1 MoisturePick-up

Somefertiliserrawmaterialsarehygroscopicwhichmeanstheycanpickupmoisturefromhumidair. Storesholdingthesematerialsshouldbeair-conditionedorthematerialshouldbecoveredwhennotbeingused. Figure2showsthecriticalrelativehumidityforanumberofcommonblendcomponentsandmixtures.Thelowerthecriticalrelativehumidity,themoremoisturewillbetakenfromtheair. Generallythephosphatesincludingtheammoniumphosphateshaveahighcriticalrelativehumidityand thus almost never present hygroscopic problems. The opposite applies to nitrates such ascalciumammoniumnitrate,ammoniumnitrate,andespeciallycalciumnitrate.

Forblendedandcomplexfertilisersthecriticalrelativehumidityinmostcasesisbelowtheaveragederivedfromitscomponents. ThiscanbeseenwhenlookingatthedataforPKandNPKfertilisers. Anextremeexampleforthisisdemonstratedbythecriticalrelativehumidityofablendconsistingofurea and ammoniumnitrate. Such ablendwouldpickupmoisture soquickly that itwouldbeimpossibletohandleitinadrystate,evenifspreadingoccursimmediatelyafterblending.

Figure 2:Critical relative humidity of fertiliser salts andmixtures [15]. Values are % relativehumidityat30°C.

3.3.2 Contamination

Crosscontaminationofrawmaterialsshouldbeavoidedasthiswillobviouslyaffecttheirchemicalanalysisandhencethefinalanalysisoftheblends.

Ammoniumnitrateandothermaterials containingammoniumnitratemustbekeptwell clearoforganicmaterials.

COMPONENT CRIT. REL. HUMIDITY

Triple Superphosphate

Mono-ammonium Phosphate

Di-ammonium Phosphate

Ammonium Sulphate

Potassium Chloride

Sodium Nitrate

Calcium Ammonium Nitrate

Ammonium Nitrate

Calcium Nitrate

BLENDS OR COMPOUNDS

PK Fertilizers

NPK Fertilizers

Urea - Ammonium Nitrate

Average data for 30 °C from Adams, Merz et al.,Runge et al., Silverberg, Löhner.

93,6 %

91,6 %

82,5 %

79,9 %

77,0 %

74,6 %

72,4 %

61,3 %

59,4 %

46,7 %

69,4 %

64,7 %

18,1 %

Goodhousekeepingisvitaltoanyblendingoperation.Allspillagesshouldbesweptupassoonaspossible andall equipment kept clean. Overhead conveyorsmustbe kept in good condition tominimise spillage into other storage areas. Theuse of special chutes to avoid excessive dust isstronglyrecommended.

FurtherinformationonthepreventionofcontaminationisgiveninReference12

3.4 SCREENING

Rawmaterialsshouldbescreenedbeforebeingfedtotheblendingunittoremoveanylumpsorfineswhichmayhaveformedduringstorage.Ifscreeningisperformedafterweighingandblending,someoftherawmaterialwillbelostandthiswillalterthecompositionofthefinalmix. Insuchcasestherecanbenocontrolonthefinalanalysisoftheblend. Inaddition,thescreeningprocessmayseriouslyun-mixthecomponents. Theuseofascalpingscreen(forexample10mmmesh)toremoveanylumpswhichmayhaveformedinthesystem,isacceptable.

3.5 SAMPLINGANDTESTING

Randomspotchecksoftherawmaterialsbeingfedtotheblenderarerecommended. Thesemaybesimplechecksoftheparticlesizedistributionbut ifthere isanydoubt,representativesamplesshouldbetakenandexaminedfully.

Forfurtherinformationaboutsamplingandphysicaltestmethods,refertoChapter8.

3.6 MICRONUTRIENTSANDCONDITIONINGAGENTS

3.6.1 Micronutrients

It is relatively simple to add micronutrients to blended fertilisers either as granular or powdermaterials, but the homogeneity of distribution is particularly important. As a guide, granularmaterialsshouldnotbeusedifthemicronutrientcarrierrepresentslessthan5%ofthetotalweight. Inthesecasesitispreferabletoaddthemicronutrientinpowderformwithabindingagenttoensuregoodadherencetothegranules.Suitablebindingagentsincludeheavyviscosityoils,UANsolutionsandwater. Alternatively,themicronutrientsmaybeaddedasasolutionwhichissprayeddirectlyontotheblendinthemixer. Notehowever,thatoilshouldnotbeusedwhenammoniumnitrateformspartoftheformulation.

Somenationalregulationsdonotallowtheuseofoil:pleasecheckthispointcarefully.

3.6.2 ConditioningAgents

Anti-cakingagentsarenotnormallyrequired if theproduct is tobeused immediately. Productswhicharetobestoredorbaggedmayrequiretheadditionofasmallamountofanti-cakingagent. Itisrecommendedthatadust-suppressantisaddedtotheblend.

Conditioningagentsmaybeappliedinthesameoperationasthemicronutrients.

4. BLENDINGEQUIPMENT

Allblendingplantsshouldincludethefollowingequipment:

1 Weighingorotherproportioningdevice(s)

2 Drymixer

3 Loadingorbaggingequipment

Inaddition,somecontrolequipmentisdesirablebutnotessentialiftheotherequipmentisreliable.4.1 SELECTION

Thishandbookdoesnotsetouttorecommendequipmentoveranyotherbuttherearevarioustypesandtheircharacteristicsandadvantagesaredifferent. Thecapacityoftheequipmentshouldbechosentomatchoutputrequirementsintermsoftonnesperhourandtonnageperweek.

4.1.1 Weighing

Inbatchoperations,thewholeequipmentmaybemountedonaloadcellorbeltweighersmaybeused. Forcontinuousblending,individualbeltweighersmaybefittedtothebeltsfeedingtherawmaterialstothemixer. Thesizeandtypeofsuchequipmentshouldbechosentomatchtheplantsizeandoutputsrequired.

4.1.1.1UnitBatchWeighing

Thesearethemostpopularsystems.Theoutputsrangefrom20to100tonnesperhour. Smallersystemshaveafloormountedhopperwithload-celldigitalreadout,fedfromafrontendloader. Therawmaterialsareweighedintheproportionsdeterminedbytheformulation. Batchesarethenconveyedtothemixingunit.

Largerunitsarenormallyfedfromoverheadholdinghoppers.

4.1.1.2ContinuousWeighing

Thesesystemsprovideacontinuousfeedtothemixerbybeltconveyorsandmaybecontinuousbeltweighersorconstantratefeeders.Intheformertherawmaterialsarefedontofixedspeedextractorweighbeltsfittedwithload-cells.Variationsinweightaretransmittedtothecontrolunitwhichadjuststhehoppergateopening.Constantratefeedershaveafixedhoppergateopeningandthebeltspeediscontinuouslyadjustedtothepredeterminedrateofoutput. Aloadcellcontinuouslymonitorstheamountofmaterialontheextractorconveyorandsendssignalstothemotorspeedcontrolunit.

Inbothsystems,informationfromtheindividualweightorspeedcontrollersisfedtoacentralcontrolunitwhichcanbepre-setfortherequiredoutput.

4.1.2 VolumetricFeeding

Forsomeblendingoperationsitissufficienttousevolumetricmeasuringoftherawmaterialstoobtainthecorrectproportionsintheblend. Aseparatehopper,usuallyfedbyfrontendloader,mustbeprovidedforeachrawmaterial. Allthecomponentsarehandledsimultaneouslyandtheunitsarecontrolledtogivetherequiredblendratio.

Thissystemhowever,reliesonconsistentrawmaterialdensitiesandmanyuncontrollablevariablesmaycausechangesinthebulkdensity. Oneofthesefactorswillbetheparticlesizesofthegranulesandthesemayvarythroughoutastorageheap.

4.1.3 Mixers

Theblendingequipmentisamajordeterminingfactorintheproductionofgoodqualityblends.

Differentdesignsofmixersareavailablesuchasrotatingdrums,coneendedtiltingmixers,stationarymixerswithinternalpaddles,verticalmixersandvolumetricmixerswithvariablespeedscrews. Inaddition,blendingmaybecarriedoutwithouttheuseofaspecificmixer. Inthissystemallrawmaterialsarefedontoacollectorbeltconveyorand,aseachmaterialisconstantlyfedatthecorrectweight,allmaterialsareconstantlylayeredontothebeltinthecorrectformulationratio. Thusacrosssectionofthatbeltwillatanytimehavethecorrectnutrientcontent. Subsequentmixingatbeltchangeoversastheblendmovesthroughtheremainderoftheplantensuresacorrectmixatalltimes.

The choice of design will depend on individual circumstances and is outside the scope of thishandbook. However,oneaspectofmixingwhichisofimportanceisthemixingtime.Mixingtimesarenormallyaroundtwominutesandtimesabove5minutesarenotrecommendedbecauseoftheriskofparticlebreakdownanddeteriorationofthemixingquality.

Afterinstallation,themixermustbetestedtodeterminethatsatisfactorymixingisachieved. Itisrecommendedthatacoefficientofvariationoflessthan10%isachieved. Descriptionsofmixingtestscanbefoundinreferences[1]and[11].

4.1.4 LoadingEquipment

Atallstagesafterthemixing,greatcaremustbetakentoavoidsegregationoftheblendcomponents. Thismeansthatconingmustbeavoidedatallstages.

Thefinalsectionoftheblendingplantmayincludereceivinghoppersforbulkloadingorbaggingbutinthesimplestcasetheblendedmaterialmaybeloadeddirectlyontotrucksfromaconveyorsystem.

Further information on equipmentmay be obtained frommanufacturers or by reference to theliterature[16],[18],[19],[27]and[29].

4.2 TESTING/CALIBRATION

Asaminimumcontrol,recordsmustbekeptofall formulations,batchrecords,weightorvolumesettingsandrawmaterialanalysesandsources. Inadditionthefollowingaretoberecommended:

1 Regularchecksofweighingorvolumetricmeasuringequipment(minimumfrequency,oncepermonth)

2 Frequentcheckweighingforbaggedmaterial

3 Randomchecksofthechemicalanalysisoffinishedproducts(minimumfrequency,onceaweek)

FurtherinformationisgiveninChapters7and8

4.3 OPERATIONS

Fullwrittenoperatinginstructionsmustbeavailableforallpersonnel. Operatingproceduresshouldbewelldocumentedandreviewedatregularintervals. AccreditationtoISO9000isnotessentialbutisrecommendedasitoffersanindependentassessmentofallprocedures.

5. SEGREGATION

Segregation is the separation of particles due to differences in physical characteristics. Forsegregationtotakeplacetheremustbemovementbetweentheparticles.

Variouscharacteristicsmaycausesegregationbutthemostcommonareparticlesize,particledensityandparticleshape. Thesize iscertainlyby far themost important factortoexplainsegregationduringflow. Duringspreading,thethreepropertiesplayarole,theshapebeingtheleastimportantandthesizeagainhavingadominatingeffect.

From the above it is seen that segregation may occur during manufacture, bulk transport (andhandling)orduringapplicationtothesoilorcrops. Theeffectsasseenbythecropsmaybethesameinallcasesunlessremixingtakesplaceduringlaterhandlingstages.

ThefollowingextractfromStairmand[26]dealswiththeproblemsofstorageinhoppersandthisisrelevanttobulkhandling,baggingoperationsandspreading.

“Thetwomainfactorsareavoidanceofsegregationinfillingandemptyingandensuringthehopperwillbe“self-clearing.” Inexaminingthequestionofsegregationinfilling…ifthematerialischargedintothehopperfromasinglepoint,thecoarserparticleswillmigratetotheouteredgesandacentralcoreofmaterialcontaininganexcessoffineswillform. Ifnowfillingisdiscontinuedandthehopperisallowedtodischargeitwilldosoinzones…Ifthezonescontainparticlesofdifferentsizesduetosegregation in filling,nodevice fittedat theconedischargetoremixcanpossiblybeeffective. Ifhowever,thehopperisfilledwithoutsegregation,littlesegregationwilloccurwhenemptying.”

By applying the above to blending, it can be seen that the avoidance of segregation and thesubsequenthandlingoftheproduct,isthemostimportantpartofanyblendingprocess. Thismaybeachievedinthreeways:

1 Thecarefulmatchingoftheblendcomponents

2 Thedesignofhoppers(seeLeonard[19])

3 Theloadingmethodsofthehoppersandvehicles,etc.

The origin of the segregation is always a difference of physical properties leading to a physicalseparationoftheparticleswhichmayormaynotresultinachemicalsegregation. Sizesegregationmayalsooccurwithinrawmaterialsorcomplexfertilisersbutthiswillhaveno(orverylittle)effectonthe chemical content. However, in bulk blends, physical segregation often leads to chemicaldifferences.

5.1 FLOWSEGREGATION

Care must be taken when storing any material to avoid size segregation in the storage heaps. Whenevergranularmaterialfallsfreelytoformaconeorpartcone,thelargerparticleswilltendtorundowntheoutsidewiththesmallerparticlesremainingnearthecentreofthecone. Shouldthishappen,theremaybequitelargevariationsinsizecharacteristicsbetweenvariouspartsofaheapandthiscouldhaveseriouseffectsonallfertilisers(Figure3). Batchestakenfromasegregatedheapcan

thusdiffer inparticlesizes,and thiswillaffect thespreadingwidthofacentrifugal spreaderwithstraight,blendedandcomplexfertilisers.

Figure3. Illustrationofflowsegregationwhenconingoccursduringloading[15]

Theremaybesomeremixingatlaterhandlingstages. Suchremixingmaybecausedsimplybytippingabagoffertiliseroutintoahopperorevenmoresimplybyturningalooselyfilledbagover. Remixingmay also occur during loading and unloading of bulk fertiliser (Figure 4). However, systematicremixingcanrarelybecountedon.

Figure4. Remixingofsegregatedfertiliserwhenunloadingbins[15]

vertical storage, full cone(vert. cross - section)

horizontal storage, half cone(vertical cross - section)

coarse granulesdominating

loading

fine granulesdominating

Unloading bins in vertical direction

Unloading large horizontal bins by payloader

Mass - flow

Remixingoccurs aftersegregation

Mass - flow forced by stirringin bins of a spreader.Remixing occurs.

Core - flow

Unloadingstarts inthe center.Thus finesare unloadedfirst. stirring

device

Some remixing occurs, but when unloading starts,coarse particles dominate. And when the left part of the bin in taken, fines prevail.

spreader - bins

Itisessentialthatallhandlingequipmentisconstructedtominimisesegregation.Theuseofspeciallydesignedchutesisrecommendedtoavoidsegregationandexcessiveamountsoffreedust.

Examplesoftechniqueswhichmaybeusedtoavoidsegregationinclude(Figure5):

“Eggcrate”bafflesinsquareorrectangularhoppers,

Concentricconedistributorsforcylindricalhoppers,

Flexiblespoutsfordirectloadingequipment.

Figure5–Preventionofsegregationinhoppers[18]

Inthecaseofrawmaterials,thesegregationismainlyasizesegregationwhichhaslittleeffectonthechemicalcontent. Forblends,theriskistohavebothsizeandchemicalsegregation.

Testsoffillingandemptyingcontainershaveshownthatgranulometricsegregationiswelllinkedwiththegranulometricspreadindex(Figure6). Itisrecommendedthatthegranulometricspreadindex

S ubd iv id ing the hopperload ing

vertica l c ross-section horiz . cross-section

in te rna l egg - c ra te ba fflesprevent the fo rm ationo f a la rge cone

S ubd iv id ing the feed ing - linevertica l c ross-section horiz . cross-section

d is tribu to r cons is tingo f severa l concen tric conespreven ts fo rm ationo f a la rge fe rtilize r - cone

V ary ing the load ing - po in t

m oving conveyor spou t

load ing

oftheblendislimitedtobelow20. ThismeansthattherawmaterialsmusthaveanevenlowerGSI(seeTable2page30)

Thefiguresbelowdistinguishthreerangesofsegregation:Lowsegregationmeansthatforthegivendifferenceofpropertythefinalsegregationhaslittleimpact–Mediumisthesituationwherethefinalsegregationbeginstobesignificantbutifthereisanotherunfavourablecondition,forexamplelowoverlappingduringspreading,thefinalresultmaybebad–Highistheworstsituationwheretherearenegativeeconomicand/orenvironmentalconsequences.

Figure6:Relationbetween size segregationandGSIofbulkblendswhenemptyinga container(segregationisthedifferenceofd50betweenthefirstandthelastthirdofemptyingacontainer)[20]

Chemicalsegregationisrelatedtotheabsolutesumofthedifferenceofd16andd84ofeachcomponent(Figure7). Thismeansthatifthefineparticlescomefromonerawmaterialandthecoarseparticlesfromanother,thesizesegregationinducesachemicalsegregation.

10 20 30 40 50

Granulometric Spread Index of the blend (GSI)

Figure7:Chemicalsegregationinrelationwiththeabsolutesumofthedifferencesofd16andd84ofthecomponents.[20]

5.2 TRANSPORTSEGREGATION

Itisoftensaidthatblendsaresubjectedtoserioussegregationduringvehicletransportbutthisisnottrue. Thelevelofvibrationintransportvehiclesisnothighenoughtoinduceamovementofthefertiliser. In fact, the segregationoccurswhen filling (andemptying) the container asdescribedabove.

Duringtransport,onlypercolationofverysmallgrainsbetweenthe largeronescanoccur. Withcommonfertilisers,thisphenomenonappearsifthereareparticlessmallerthan0,5mm. Abovethissize,theprocessistooslowtohavearealimpactonthefinalproduct.

5.3 SPREADINGSEGREGATION

Blenders should have some knowledge of the kinds of spreading equipment available and theadvantagesanddisadvantagesofthesewhenusingblendedfertilisers. Blendersshouldbepreparedand able to advise farmers on the type of equipment to use and the setting up, calibration andmaintenancenecessary. Thismeansthattheyshouldbepreparedtogiveasmuchinformationaspossibleaboutthephysicalqualityoftheirproducts.Suchinformationmayincludethecomposition,bulkdensityandflowcharacteristicsaswellastheparticlesizedistribution. Thisisanotherreasonforkeepingadequaterecordsofrawmaterialsandproductbatches.

Centrifugal, pneumatic, and auger spreaders are available. The segregation inducedbyphysicaldifferencesofthefertiliserparticlesmaybeduetotrickling,asisthecasewithaugerspreaders,ormaybecausedbytheaerodynamicresistanceoftheparticleswhenthrownthroughtheair,aswithcentrifugalandpneumaticspreaders.

0 10 20 30 40 50 60 70 80

Difference between raw materials (absolute sum of difference d16 and d84/d50mel)

However,anysegregationduringspreadingmaybecompletelycompensatedforbytheoverlappingofadjacentspreadingswaths. Thisleadstothequestion,howmuchoverlapping?

Asageneralguide,pneumaticspreaderswillnotinducesegregationbecauseofthelargeamountofoverlapping(fromthespouts). Theeffectsofsegregationfromcentrifugalspreaderswillbereducedbyoverlapping.

Auger spreaders will segregate heavily. Since these spreaders, when correctly adjusted have arectangularlateralmassdistribution,nooverlappingoccursandthusalsonoreductionofsegregationtakesplace. Forthisreason,augerspreadersarenotrecommendedforblendedfertilisers. Furtherinformationmaybefoundinreference[2].

InWestern Europe, themost common devices are centrifugal spreaders with two discs. Theirworkingwidths(widthbetweentractortracks)varybetween12andmorethan36m. Thespreadingwidthcanreachmorethan50m.

Segregationoccursduring spreadingdue tophysical differencesbetween the componentsof theblended fertiliser. The larger,heavierandmore spherical theparticlesare, the further theyarespread. Thesizeanddensityarethemajorfactors(Figure8,Figure9andFigure10).

Thechartsshowthesegregationasafunctionofthedifferenceofagivenphysicalproperty(size,densityorshape). Theconsideredblendshavetwocomponentsinaproportionof50%andthesearephysicallysimilarexceptfortheanalysedproperty.

Figure8:Evolutionofthesegregationwiththedifferenceofd50betweenthetwocomponents[20]

Figure9:Evolutionofthesegregationwiththedifferenceofdensitybetweenthetwocomponents.[20]

0% 10% 20% 30% 40%

d50 difference between raw materials (%)

0% 10% 20% 30% 40% 50% 60% 70%

Loose density difference between raw materials (%)

Figure10:Evolutionofthesegregationwiththedifferenceofshapebetweenthetwocomponents.[20]

In practice, the components present differences for more than one physical property and eachdifferencecanaccentuateorreducethefinalsegregation. Forexample,sizedifferencebetweencomponentscancompensateforadensitydifferenceandviceversa. Thelarger,heavierandmoresphericaltheparticlesare,thefurthertheyarespread. Forexample,ureawhichhasalowdensityincomparisonwithother fertilisersshould ideallyhave largesizedparticleswithad50near themaximumtoleranceinordertolimitspreadingsegregation.

The final impact of segregation during spreading can be significantly reduced by appropriateoverlappingbetweenthepasses. Indeed,thesegregationisgenerallymarkedinsuchawaythatonecomponenttendstoaccumulatebehindthespreaderandanothertendstobespreadfurther. Iftheoverlappingbetweenthepassesissufficient,ateachplaceinthefieldthefinalquantityoffertilisercomesfromtwopasses(Figure11,topandcentre). Withagoodspreadercorrectlyadjusted,itisevenpossible forworkingwidthsup to24or28m. However, forbadlyadjusted spreaders thesegregation remains. Practically,acorrectoverlappingmeans that thespreadingwidthmustbeaboutdoubletheworkingwidth. Sowithaworkingwidthof24m,itmeansthatthespreadingwidthmustapproach48m. Figure11,below,showsanexampleofinsufficientoverlapping,resultingfromaworkingwidthwhichismuchgreaterthanhalfthespreadingwidth.

0% 20% 40% 60% 80% 100%

Elongation (shape) difference between raw materials (%)

Figure11:Illustrationoftheoverlappingforthesamebulkblendbutforworkingwidthsof20,28and36m.[21]

-28 -26 -24 -22 -20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28

Distance from the axis passage (m)

ity (%

Dose (% ) Central passage Left passage Right passage

Left Right

Overlapping

Working width = 20 m

-28 -26 -24 -22 -20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28

ity (%

Overlapping Overlapping

Left Right

-28 -26 -24 -22 -20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28

ity (%

O verlapping

Left Right

O verlapping

Anotherimportantpointtomentionisthatwithhigherworkingwidths,itbecomesdifficulttofindthecorrectadjustment. Thisisnotonlythecasewithblendsbutalsowithstraightorcomplexfertilisers. Theuseofacontrolkitiscertainlyrecommendedforthefarmer(Figure12below).

Figure12:Illustrationofakittomeasurespreadingquality

Goodadviceforfarmersistolimittheworkingwidthinordertoobtainanimportantoverlapping. Inpracticethismeanschoosingaworkingwidth lowerthan24or28mwithahighperformancespreader.

5.4 EFBAQUALITYRECOMMENDATIONS

Toreducesegregationproblems,itisrecommendedtoblendrawmaterialshavingsimilarphysicalproperties, themost importantbeing thesizeof theparticles. TheEuropeanFertilizerBlendersAssociation (EFBA) has defined quality recommendations for the particle sizes (Table 2). Therecommendationsconcentrateonad50around3,25mmwithalimitedgranulometricspreadindex(GSI). Iftherawmaterialscomplywiththeserecommendations,flowsegregationisnotsignificantandspreading segregationonlyoccurs if thereare importantdensityand/or shapedifferences. Thishappensonlywhencertainspecificfertilisersareused.

Table2-Targetsandtolerancesforthegranulationofblendcomponents.

EFBATargetsandTolerancesforthegranulationofrawmaterialsforfertiliserblending

Verbalnotation Physicaldimension MeanParticleSize d50inmm 3,25

mm ±0,25mm

FineParticles <1mm,%ofmass 0% 0,25%CoarseParticles >5mm,%ofmass 0% 1%MainRange 2,5–4,0mm,%ofmass 90% ±5%GranulometricSpreadIndex(GSI)

100 d 2

1684 ddGSI -=

ItisassumedthatthesieveanalysisiscarriedoutaccordingtoEuropeanStandardEN1235/A1.EFBArecommendstheuseofthesesevensieves:1,00mm–2,50mm–2,80mm–3,15mm–3,55mm–4,00mm–5,00mm(thejustificationforthesesievesislinkedtotherecommendations)

6. SAFETYCLASSIFICATION–LABELLING-DISTRIBUTION

Blendersmustbeawareofthehazardsassociatedwithrawmaterialsandfertilisers,especiallythosecontaining ammonium nitrate. Recognition of the hazards is made simpler by classificationsystemssuchas thosepreparedby theUnitedNations (UN), InternationalMaritimeOrganisation(IMO)andtheEuropeanCommission(EC). AllproductsmustbelabelledaccordingtoNationalandEuropeanRegulationsandinsomecircumstancesonlypackagedfertilisersmaybesuppliedtotheenduser.

FullaccountshouldbetakenofallindustryguidanceandCodesofPracticesuchasthosepreparedbyFertilizersEurope[12,13]

6.1–Labellingandmarketingoffertilisers AnyfertilisersplacedontheEuropeanornationalmarketmustbecorrectlylabelledinaccordancewitheithernationalorECregulations,dependantonthemarketinwhichitistobesold.Theseregulationsnormallycovermatterssuchasnutrientcontent,safetyandprotectionoftheenvironment.Mineralfertilisers,offeredforsaleontheEuropeanmarket,needtocomplywithEuropeanCouncilRegulation2003/2003/EC[25]. Forpackedblendedfertilisers,thelabellinginformationmustbeplacedonthepackaginginaconspicuousposition.Labelsmustbeattachedtothepackageortowhateversystemisusedforclosingit.Markingsmustbe,andmustremain,indelibleandclearlylegible(2003/2003/EC,Art.10).Forbulkblendedfertilisers,thesemarkingsmayappearontheaccompanyingdocuments(2003/2003/EC,Art.7).MarkingsmustappearinatleastthenationallanguageorlanguagesoftheMemberStateinwhichtheECfertiliserismarketed.

Figure13:ExampleofEClabelforasolidmineralfertiliseraccordingtoEC2003/2003. 6.2–Labellingandclassificationofhazardoussubstancesandmixtures(CLPregulation):hazardlabellingEuropeanRegulation1272/2008/ECconcernstheclassification,labellingandpackagingofsubstancesandmixtures[23].Itisknownbyitsabbreviatedform,‘theCLPRegulation’orjustplain‘CLP’.

TheCLPRegulationadoptstheUnitedNations’GloballyHarmonisedSystemontheclassificationandlabellingofchemicals(GHS)acrossallEuropeanUnioncountries.

Beforemanufacturing,eachblendedfertilisercontaininghazardoussubstancefromrawmaterialmustbeclassifiedaccordingtotheCLPregulations.

Theclassificationoftheblendedfertilisersdependsontheconcentrationofhazardoussubstancesinthefinalproduct.Allclassifiedfertilisersrequirehazardlabelling.

Name or trade name and address of the manufacturer

TRADE NAME OF THE FERTILIZER

EC FERTILISER

NPK fertiliser blend (Ca0) (S03) 7 - 14 - 25 (2) (14)

7 % of total nitrogen (N) 7% of ammoniacal nitrogen (N)

14 % of Phosphorous pentoxide (P2O

5) soluble in neutral

ammonium citrate and in water 13,1 % of water-soluble phosphorous pentoxide (P

25 % of water-soluble potassium oxide (K2O)

2% of water-soluble calcium oxide (CaO) 14 % of total sulphur trioxide (SO

11,5% water-soluble sulphur trioxide (SO3)

xx kg net

Company name and address

Type denomination followed by « blend »

Indication of main nutrients (N, P and K) complying to 2003/2003/EC regulation

Optional identification of secondary nutrients

Net or gross mass + tare mass

Figure14:ExampleofhazardlabellingaccordingtoCLPregulationforafertilisercontainingover3%oftriplesuperphosphate.

Thesizeofthelabelisalsodefinedaccordingtopackagingvolume:Packagingvolume Labelsize(mmm) Pictogramsize(mm)>500liters(BigBag) Mini148x210 Mini46x46>50litersand≤500liters Mini105x148 Mini32x32>3litersand≤50liters Mini74x105 Mini23x23≤3liters Mini52x74ifpossible Mini10x10(16x16ifpossible)

Thelabelofafertiliserwhichdoesnotmeetthecriteriaforclassificationashazardousbutcontainsahazardoussubstanceinaconcentrationlevelwithsafetydatasheetavailableondemandshallbearthestatement:EUH210—‘Safetydatasheetavailableonrequest’.

Forammoniumnitrate,theOxidizingpictogramfromCLPcanbereplacedbytheADRpictogram(5.1class)onthelabelbutH272hazardstatementshallremain.

TRADE NAME OF THE FERTILIZER

NPK fertiliser blend (Ca0) (S03) 7 - 14 - 25 (2) (14)

Contains triple superphosphate triple (n°EINECS : 266-030-3, n° CAS : 65966-95-4)

DANGER H318 : Causes serious eye damage

P280 : Wear protective gloves/protective clothing/eye protection/face protection.

P305+P351+P338 : IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses if present, and easy to do. Continue rinsing.

P310: Immediately call a POISON CENTRE or doctor/physician.

xx kg net Company name, address, phone number

Name, address, phone number of supplier(s)

signal word, hazard and precautionary statements

Nominal quantity of fertiliser in packaging

(except if mentioned elsewhere on the packaging)

Product identifiers

Hazard pictogram (in colour, covering at least 1/15th of the label, minimum size 1 cm²)

Type denomination name Name and identification number of hazardous substances contributing to classification (4 max except if > 4 hazard classes, then à 1 for each hazard)

Trade name

6.3 –Regulationrelatedtohazardoussubstancesandmixtures(REACHregulation):Safetydatasheet(SDS)

REACHRegulation1907/2006/EConRegistration,Evaluation,Authorisation&RestrictionsofChemicals)definesSafetyDataSheetasthemaininformationvectoronproducthazardsandgoodpractices(Art.31)[24].

ASafetyDataSheet(SDS)ismandatoryandistobepro-activelyprovidedtotheclientifthefinalproductisclassifiedashazardousinaccordancewithCLPRegulation.

ASDSistobeprovidedtotherecipientathisrequestwhenthefertiliserdoesnotmeetthecriteriaforclassificationashazardousinaccordancewithCLP,butcontains:

• 1%ormoreofasubstanceclassifiedashazardous • 0.1%ormoreofasubstanceclassifiedaspersistent,bioaccumulativeandtoxicorvery

persistentandverybioaccumulativewhichisonthelistofsubstancessubmittedtoauthorisation(REACH)

• asubstanceforwhichthereareCommunityworkplaceexposurelimits.

AnySDSshallbeprovidedfreeofcharge.

Forfertilisersclassifiedashazardous,theSDSshalltobeprovidedonpaperorelectronicallynolaterthanthedateonwhichthefertiliserisfirstsupplied(REACHArt.31-8).Thereisnoneedtoprovideitateachdelivery.

UpdatesofSDSshallbeprovidedtoallformerrecipientstowhomfertiliserhasbeensuppliedwithinthepreceding12months(REACHArt.31-9)

SDSshallbeprovidedinthelanguageofthecountrywheretheproductissold.

SDSshallfollowtheproductfromitsmanufacturetoit’senduse:

Distributionàforwardingofsupplier’sSDStotheclient.

PackagingàTransmissionofaSDSinthenamethecompanyresponsibleforplacingthefertiliseronthemarket.

BlendingàTransmssionofaSDSspecifictotheblendedfertiliserinthenamethecompanyresponsibleforplacingthefertiliseronthemarket.

Thesafetydatasheetshallbedatedandshallcontainthefollowingheadings:

1.identificationofthesubstance/mixtureandofthecompany/undertaking; 2.hazardsidentification; 3.composition/informationoningredients; 4.first-aidmeasures; 5.fire-fightingmeasures;

6.accidentalreleasemeasures; 7.handlingandstorage; 8.exposurecontrols/personalprotection; 9.physicalandchemicalproperties; 10.stabilityandreactivity; 11.toxicologicalinformation; 12.ecologicalinformation; 13.disposalconsiderations; 14.transportinformation; 15.regulatoryinformation; 16.otherinformation.AsetofStandardisedSafetyDatasheetsforthemostcommonfertilisersareavailableonrequest.

Keystepsaccordingtohazardoussubstancesregulation:

ðCheckifpresenceofhazardoussubstancesinrawmaterials:superphosphates,ammoniumnitrate…ðClassifythenewfertiliserinaccordancetohazardoussubstancesregulation(CLP)ðLabelthenewfertiliserinaccordancewithhazardoussubstancesregulation(CLP)whenneededðCreatetheSafetyDataSheetinaccordancewithREACHifneeded

7. QUALITYCONTROL

Blendersshoulddrawuparoutinequalitycontrolscheduletoincludethesamplingandanalysisofrawmaterialsandproductsaswellaschecksonrawmaterialweighersand/orfeedersandcheckweighingoffinishedbaggedproducts.

7.1 RAWMATERIALS

Theamountofqualitycontrolofrawmaterialsdependsonthereliabilityofthesuppliers. Ifsuppliesarereceivedfromsinglesources,experiencewillsoonestablishthedegreeofcontrolneeded. Ifrawmaterialsarepurchasedfromavarietyofsources,extracontrolisessential.

RandomsamplesfromeachconsignmentshouldbetakenasdescribedinChapter8,forreferencepurposes. Thesesamplescanbesentforanalysiswheneverthereisreasonfordoubtbuttheyshouldbecarefullylabelledwithdateandoriginandkeptforatleastthreemonths.

Asmentioned in section 3.2, theparticle size distribution of the rawmaterials is themostimportantpropertytobecontrolled. RepresentativesamplesofrawmaterialfeedsshouldbetakenandtestedasdetailedinChapter8atregularintervalswithaminimumfrequencyofoncepershift.Afullsieveanalysisshouldbecarriedoutoneachrawmaterial.

7.2 FINISHEDPRODUCTS

AllblendershaveanobligationtomeettherequirementsoftheirNationalFertiliserRegulationsandforthosefertiliserswhicharemarketedasECfertilisers,commonRegulationEC2003/2003[25]applies throughout theCommunity. NationalRegulationswill coverproductswhicharenot declared as EC fertilisers. It should be noted that in caseswhere the farmer does notpurchasea fertiliserwitha specifiednutrient ratio, forexample, ifhepurchaseshisownrawmaterialsandcontracts theblender tomix them forhim,allofficial controls for theblendedfertilisermaynotapply.

The regulations set out the tolerances on the declared chemical analysis for all fertilisers. Fertilisersnotmeetingthesetolerancesmayresultinprosecutionandpenalty. Itisthereforerecommendedthatsomedegreeofqualitycontrolisexercisedbyblenders(auto-control).

The amount of quality control requiredwill depend verymuch on the scale of the blendingoperation. Forsimplesmallscalebatchblendingoperationsitmaybesufficienttorelyontheprinciplethat“whatgoesinmustcomeout”. However,eventheseoperationswillneedsomeregularcontroloftheweighingequipment.

Forlargescalecontinuousoperations,considerationshouldbegiventofullautomatedon-linesamplingandanalysis.

Inbetweenthesetwoextremes,itisrecommendedthatonerepresentativerandomsampleistakenfromoneofthegradesmadeeachday. Iflaboratoryfacilitiesareavailableonsite,thesesamples should be analysed daily. If outside contract laboratory services are used, thefrequencyofanalysis shouldbeat leastone sampleperweek, selectedat random from theweek’scollection.

Recordsshouldbekeptofallsamplestakenandanalysescarriedout.

8. SAMPLINGANDANALYSIS

8.1 SAMPLING

Representative sampling of any material requires special techniques and equipment. Fulldetails are outside the scope of this handbook but it is recommended that blenders followrecognisedsamplingmethodssuchasthosesetoutinEuropeanStandardEN1482Part1[9].

Itisessentialthatallsamplesarecorrectlytakentoensuretheirrepresentativity. Thereisnopoint in taking and analysing unrepresentative samples. The quality of the measurementsmade on the samples depends on their representativity. This is particularly important forblendedfertiliserswheretheriskofheterogeneityishigher.

AsstipulatedbyCEN,blendedsamplesmustalwaysbetakenfrommaterialinmotion,eitherinfreefalloronconveyorsystems.Itisessentialtosamplethroughthewholestreamratherthanfrom the same part of the stream. Suitable automated equipment is available for mostcircumstancesandistoberecommendedwheneverpossible.

Fortheblendproduceritisimportanttoknowthesamplingandmeasurementmethodsandthenecessary equipment. Generally, all of this is described in standards which are regularlyupdated.Blendersarerecommendedtostudythelatestversionsofsamplingandmeasurementstandards.

Whenasampleofanygranularmattermustbetaken,somequestionsshouldbeasked:

1 WhatquantitymustItake?

2 Howmanyincrementstoobtainthisquantity?

3 Howtotakethesamples?

Finallythesamplemustbereducedinordertoobtainafinalsampleforanalysis(usuallyabout250gforsievingtestand500gforachemicalanalysis). Thusafterthesamplingthereisalsoareductionstep. FulldetailsofreductionmethodsaregiveninEN1482Part2.

8.1.1 SamplingQuantity

The minimum quantity of sample recommended is given in EN 1482 Part 1. Therecommendationsaresummarisedasfollows:

Table4:Recommendedquantitytosampleforbaggedproducts

NumberofbagsMinimalnumberofincrements<5bagsAsamplefromeachbag4<numberofbags<114bags10<numberofbags<401Wholenumberabove thesquare rootof the

numberofbags>400bags20bags

If theweightofabag is less than5kg,a completebag is consideredasa sub-sample. Thenumberofselectedbagscanbehigherifthefinalquantityofthesampleisnotsufficient. Forbagsof50kg,thecontentmustideallybedividedinordertoobtainarepresentativesample(seeparagraph8.1.3). SamplingthecontentsofanIBC(bigbag)isnoteasy. Thebestsolutionistosampleduringemptying,butthisisnotalwayspossible. FurtherinformationisgiveninEN1482Part1.

Table5:Numberofsamplingunitsfromwhichincrementalsamplesaretobetakenfromabulklot

LotSizeMinimumnumberofsamplingunits25torless10Morethan25tandlessthan401tThenearestwholenumberabovethesquarerootof4timesthe

numberoftonnespresentMorethan400t40

Thedatafromthistablecanbeexpressedinamorepracticalway(Table6).

Table6:Numberofincrementsbyvehicletosampleforbulkproducts.

Numberofincrementstobetakenduringemptyingofeachdeliverytruckorwagon

LotSize

Truck Wagon25t

Wagon60t

25t 10 10 50t 7 1575t 6 100t 5 150t 4 200t 4 300t 3 500t 2 600t 2 2 41000t 1 1 31250t 1 1 12500t ½ ½ 1

Theamountoffertiliserforanincrementisabout250gforrawmaterialsand500gforblends.

8.1.2 SamplingEquipment

Appropriate samplingequipment is essential. Thereare various automated systems forusewithconveyorbelts. Thesearecertainlyrecommendediftherearelargeamountsoffertiliserhandled. Forsmallerdeliveries,manualsamplingismoresuitable. Asuitabletypeofsamplingcup is described in EN 1482 Part 1 [9] and is essential for sampling from falling streams ofmaterials(Figure15). Informationaboutthenumberofincrementstobetakenmustbegiventotheoperator(Table6).

Figure15:Exampleofasamplingcupanditsuse.

8.1.3 SampleDivider

Rotarysampledividersarerecommended,particularlywhensieveanalysisistobecarriedoutorwhenblendsarebeingtested. Riffledividersmaybeusedforrawmaterialsbutarelesssuitableforblendedproducts. Descriptionsofthesedividers(Figure16)canbefoundinEN1482[9]. Itisimportanttorememberthatforthemeasurementofthephysicalproperties,theparticlesmustnotbecrushed,butforchemicalanalysis,itisrecommendedtocrushtheparticlesbeforethefinalreductionofthesample.

Figure16:Illustrationofrotaryorriffledividers.

8.2 CHEMICALANALYSIS

Standardreferencetestmethodsformostofthecommonchemicalanalysesusedforfertilisermaterials may be found in EC Directives, National Standards, European and InternationalStandardsandtheAOACMethodsofAnalysisHandbook. Itisnotessentialthatthesemethodsare used for routine process control and simpler, often automated, methods are available. However,allsuchmethodsmustbeevaluatedagainstoneoftherecognisedstandards.

8.3 PHYSICALTESTS

Recognisedstandardtestmethodsexistforseveralphysicalproperties.Theinterestofblendersshould focus on test sieving and bulk density (see section 3.2). Some laboratories have anaccreditation for these special measurements. No Standard methods are available for such

propertiesascakingandfreedust.

Samplingisalsoafundamentalstepforphysicaltestingbecauseofthesegregationthatoccursnaturally. Thisisparticularlythecaseforsieveanalysisbecauseofthesizesegregationwhenthereisaflowoffertiliser(whichisalwaysthecaseforbulkproducts).

Anotherpointisthatforphysicaltesting,thequantityneededforthefinalsamplemaybemorethan5kg.Thismeansthatthenumberorthemassofsub-samplesmustbesufficienttoachievethis.

8.3.1 TestMethodforSieveAnalysis(ThefollowingmethodisasummaryofEN1235/A1)

8.3.1.1Principle:

Dry sieving of a sample of fertiliser material with one or more test sieves, using a mechanicalsievingmachine.

8.3.1.2Apparatus:

• Balance,capableofweighingtothenearest0,1g.• Stainlesssteelwovenwiretestsieves,200mmdiameter,withalidandreceiverforthesieves.

• Mechanicalshaker(sievingmachine),capableofimpartingbothhorizontalandverticalmotiontothematerialonthesetofsieves.

• Stopwatch• Softbrush

8.3.1.3Procedure:

Reducethesampletoapproximately250g,preferablyusingarotarysampledivider,orifoneisnotavailable,ariffledivider. Selectsevensievestocovertherangeofparticlesizeexpectedandassembleinascendingorderofaperturesizeontopofthereceiver.(SeenoteatthebottomofTable2)

Weighthetestportiontothenearest0,1gandplaceitonthetopsieveandfitthelid. Placethesetofsieveswiththesampleontheshakerandshakefor10minutes.

Removethesievesfromthenest,startingfromthetopandweighthequantityretained oneachsieveandinthereceiver,tothenearest0,1g.Removeanyparticlestrappedin themeshbybrushingfromunderneath.

Sumthemassesofthefractionsretainedonthesievesandinthereceiverandcheckthat the total mass is within 2,5g of the original mass. Calculate each fraction mass as a percentage of the sum of the masses and draw up a table showing the cumulative percentagepassingeachsieve.

Thepercentageofmaterialretainedinthereceiver(x0)andoneachsieve(xn)isobtained fromtheformula:

100 mm

n ´=nX

Wheremnisthemassonsieven mtisthetotalmass(m0+m1+…) Xnisthemass%retainedonsievenThecumulativeundersizeisdefinedbytheformula:

Cn=X0+X1+X2+…+Xn-1WhereCnisthecumulative%undersizeforsieven

8.3.2 TestMethodforLooseBulkDensity (ThefollowingmethodisasummaryofEN1236)

8.3.2.1Principle:

Weighingaknownvolumeofthefertiliser.

8.3.2.2Apparatus:

• Balance,capableofweighingtothenearest1g.• Cylinderofaknownvolume,V(approx.1litreanddiameteraround60mm).• Standardfunnelwithanapertureof25mmdiameter.

Figure17:Illustrationoftheequipmentfortheloosedensitymeasurement.

8.3.2.3Procedure:

Placethesampleoffertiliserinthefunnelwiththeapertureclosed. Weightheemptycylinderandplaceitunderthefunnel. Opentheapertureofthefunnelandallowthefertilisertoflowintothecylinder. Whenthecylinderisfull,closethefunnelandremovethe excess fertiliser above the cylinder with a spatula. Weigh the cylinder and itscontentsandcalculatetheweightoffertiliser(minkg).

Theloosebulkdensityisgivenbythefollowingformula:

8.3.3 TestMethodforAngleofRepose (ThefollowingmethodisasummaryofEN12047)

8.3.3.1Principle:

Measurementofthediameterofaheapofagivenheightandcalculationoftheangleof theheap.

8.3.3.2Apparatus:

• Funnel(apertureof25mmdiameter)placedat120mmaboveasurface.• Horizontalsurfaceof750x750mm,withfourlinespresentinganangleof45°betweenthemandtracedatthecentreofthesurface.

Figure18:Illustrationoftheequipmentfortheangleofreposemeasurement.

8.3.3.3Procedure:

Placeabout5kgfertiliserinthefunnelwiththeapertureclosed. Opentheapertureandallowthefertilisertoflowfreelyontothesurfaceandformaheap. Theflowstopswhentheheapreachesthebottomofthefunnel. Measurethefourdiametersontheplate.

Calculatetheaveragediameter(d inmm). Thevalueoftheangleofreposeisobtainedbythefollowingformula:

÷øö

çèæ=

25 - d240arctan a

8.4 EXAMPLES

Thissectiongivessomeexamplesoftheresultsofphysicaltestsonfertilisers. Thedatausedare realistic but the actual physical properties will vary considerably for the same productdependingonitsorigin[14].

Usingthemeasurementmethodsdescribedintheprevioussection,thefollowingresultswereobtainedforthreedifferentfertilisers,A,BandC. (Table7).

Table7:Exampleofdatafromthelaboratoryforphysicaltestingofthreefertilisers.

Fertiliser

Sievingtest

<1,00mm 0,1g 0,5g 8,2g

1,00to2,50mm 1,2g 9,3g 35,6g

2,50to2,80mm 5,3g 19,9g 45,2g

2,80to3,15mm 36,7g 68,1g 51,9g

3,15to3,55mm 115,2g 79,6g 46,8g

3,55to4,00mm 67,7g 51,2g 35,3g

4,00to5,00mm 15,9g 13,2g 21,7g

>5,00mm 2,1g 2,1g 5,2g

Total 244,2g 243,9g 249,9g

Loosebulkdensity

Weightof1litre(V=0,001m³) 1,000kg 0,750kg 0,950kg

Angleofrepose

Averagediameterbaseofthe

heap( d )400mm 400mm 325mm

Byapplyingtheformulaeitispossibletodeterminethephysicalpropertiesofthesefertilisers.

Table8:ExampleofcalculationforthephysicalpropertiesoffertiliserA.

SievingTest Weight Percentage CumulativePercentage

<1,00mm 0,1g 0,1/244,2=0,04% 0,04%1,00to2,50mm 1,2g 1,2/244,2=0,49% 0,04+0,49=0,53%2,50to2,80mm 5,3g 5,3/244,2=2,17% 2,17+0,53=2,70%2,80to3,15mm 36,7g 36,7/244,2=15,03% 5,03+2,70%=17,73%3,15to3,55mm 115,2g 115,2/244,2=47,17% 47,17+17,73=64,91%3,55to4,00mm 67,7g 27,72/244,2=27,72% 27,72/244,2=27,72%4,00to5,00mm 15,9g 15,9/244,2=6,51% 6,51+92,63=99,14%>5,00mm 2,1g 2,1/244,2=0,86% 0,86+99,14=100,00%TOTAL 244,2g

With the sieving test data, it is possible to determine the mean particle size (d50) and theGranulometricSpreadIndex(GSI). Thed16isjustunder3,15mm,thed50isbetween3,15mmand3,55mmand thed84 isbetween3,55mmand4,00mm. Theuseof theequation (seeparagraph3.2.1)leadstothefollowingresults:

( ) mm 3,11 2,80 - 3,15 2,70 - 17,73

2,70 - 16 2,80 16 =+=d

( ) mm 3,42 3,15 - 3,55 17,73 - 64,91

17,73 - 50 3,15 50 =+=d

( ) mm 3,86 3,55 - 4,00 64,91 - 92,63

64,91 - 84 3,55 84 =+=d

10,96 100 3,42 2

3,11 - 3,86 =´´

Thegraphicrepresentationofthecumulativepercentageconfirmsthecalculatedvalues(Figure19).

Figure19:Exampleofgranulometriccurveandgraphicdeterminationofd16,d50andd84.

Thesamemethodofcalculationisusedfortheotherfertilisers(Table9).

Table9:PhysicalpropertiesoffertilisersA,BandC.

Comparingthefertilisers,thefollowingcommentsmaybemade. Thethreeproductshavead50inaccordancewiththerecommendations(Table2). FertiliserAhasaverylowGSImeaningthatallparticlesareofsimilarsize. AttheotherextremefertiliserChasahighGSIbecauseofitshighcontentofsmallparticles. FertiliserBhasa lowbulkdensityandfertiliserChasahighangleofreposebecauseofitsmoreangularparticles.

Fertiliser

d16 3,11mm 2,85mm 2,34mm

d50 3,42mm 3,27mm 3,04mm

d84 3,86mm 3,79mm 3,83mm

GSI 10,96 14,42 24,55

Loosebulkdensity(ρ) 1000kg/m³ 750kg/m³ 950kg/m³

Angleofrepose(α) 32,6° 32,6° 38,7

0102030405060708090

1 1,5 2 2,5 3 3,5 4 4,5 5Sieve dimensions (mm)

3,11 3,42 3,86

9. FORMULATION

Thecalculationofblendformulationsisnotadifficultprocessbutitisanessentialrequirementforproducinggoodqualityblends. Theprocessveryoften isperformedbya computerandcombinedwithweigherormeteringcontrols.

Recordsshouldbekeptofeachformulationandthiscanbesimplifiedbytheuseofastandardformatinthecomputer.

Foraccurateformulationtheactualrawmaterialanalysesshouldbeusedbutstandardanalysesarehelpfulasafirstapproximation.

Example:

Productrequired: 20 10 11

Rawmaterialsavailable: N P2O5 K2O

CalciumAmmoniumNitrate(27%Nitrogen) 27 0 0DiammoniumPhosphate(18%Nitrogen46%P2O5) 18 46 0PotassiumChloride(60%K2O) 0 0 60Filler 0 0 0

1 Toobtain11%K2Ointhefinalproductrequires18,5%PotassiumChloride.

2 To obtain 10% P2O5 in the final product requires 22% Di-ammoniumPhosphateandthiswillprovide3,9%Nitrogen.

3 Theremaining16,1%Nitrogeninthefinalproductwillrequire59,5%CalciumAmmoniumNitrate.

4 Totalrawmaterialsrequiredaddsupto100%ofthetotalspaceandthusnofillerisrequired.

Formulationpertonneofproductisthus:

• 595kgofCalciumAmmoniumNitrate

• 220kgofDi-ammoniumPhosphate

• 185kgofPotassiumChloride

Formulationscontaininglessthan5%ofanyingredientshouldbeavoidedastherewillbedifficultiesinmixingthissmallamountevenlythroughoutthemixture.

10. REFERENCES

CopiesofthelistedStandardsmaybeobtainedfromtheNationalStandardsOrganisation(e.g.AFNORinFrance,DINinGermanyandBSIintheUK).

1 BalayHL,ColeCAandRutlandDW,BulkBlendingMixingEfficiencyTests.Proceedings32ndFertiliserIndustryRoundTable,Atlanta,October1982

2 Proposal:COMIFER,Guided’optimisationdel’épandagedesengraisminérauxsolides,Edition2009/2010

3 CEN,EuropeanStandard /A1.TestSieving(2003)

4 CEN,EuropeanStandardEN1236.Determinationofbulkdensity(loose)

5 CEN,EuropeanStandardEN1237.Determinationofbulkdensity(tapped)

6 CEN,EuropeanStandardEN12047.Measurementofstaticangleofrepose

7 CEN,EuropeanStandardEN13299.Determinationoftheflowrate

8 CEN,EuropeanStandardEN12944VocabularyPart1,Part2andPart3

9 CEN,EuropeanStandardEN1482.Sampling Parts1&2

10 ChevalJ-L,UpdateontheCanadianQualityAssuranceProgramandSGN.PublicationN°44,AAPFCO1991

11 ColeCA,BalayHLandRutlandDW,BulkBlendingMixingEfficiencyTest.Proceedings35thFertiliserIndustryRoundTable,Atlanta,October1985

12 Guidance for the Storage, Handling and Transportation of Solid Mineral Fertilisers. PublishedbyEFMA(2007)

13 GuidancefortheCompatibilityofFertilizerBlendingMaterials. PublishedbyFertilizersEurope(2016)

14 Guillon D. Enquête granulométrique sur lesmatières premières pour les engrais de mélange.RencontresInternationalesdel’AFCOME,Strasbourg,novembre2003.

15 Heege H. Quality of raw materials for fertilizer-blends: defining a standard. RencontresInternationalesdel’AFCOME,Strasbourg,novembre2003.

16 HignettTP,BulkBlendingofFertilisers:PracticesandProblems.Proc.Fert.Soc.N°87,March1965

17 IFA/EFMA,SelectedTestsConcerningtheSafetyAspectsofFertilisers.1992

18 LanceGEN,TheoryofFertiliserBlending.Proc.Fert.Soc.N°387,December1996

19 LeonardJE,TechnologyofFertiliserBlending.Proc.Fert.Soc.N°388,December1996

20 Miserque O. Analyse de l’influence des caractéristiques physiques des particulesd’engraissurlecomportementdesmélanges. PhDthesis–UniversityofLiège,FacultyofAppliedSciences-Belgium–2005.

21 MiserqueO.,OestgesO.,BruartJ. Thespreadingofbulkblendswitha largeworkingwidthspreader. RencontresInternationalesdel’AFCOME,Strasbourg,novembre2003.

22 PerbalG,TheThermalStabilityofFertiliserscontainingAmmoniumNitrate.Proc.Fert.Soc.N°124,November1971

23 Regulation1272/2008/ECoftheEuropeanParliamentandoftheCouncilonclassification,labellingandpackagingofsubstancesandmixtures,amendingandrepealingDirectives67/548/EEC and 1999/45/EC, and amending Regulation (EC) No 1907/2006 OJ353/131.12.2008andimplementinglegislation

24 Regulation1907/2006/EC of the European Parliament and of the Council on theRegistration, Evaluation, Authorisation and Restriction of Chemicals (REACH)OJ396/130.12.1996andimplementinglegislation

25 Regulation2003/2003/ECoftheEuropeanParliamentandoftheCouncilof13October2003relatingtofertilisers. OJ304/121.11.2003andimplementinglegislation

26 StairmandCJ,ThescreeningandSegregationofFertiliserMaterials.Proc.Fert.Soc.N°74,November1962

27 TaylorL,LatestTechnologyandMethodsUsedforBulkBlendingandFertiliserStorageintheUnitedStates.Proc.Fert.Soc.N°256,April1987

28 TheFertiliserInstitute,BulkBlendQualityControlManual.Washington,Spring1996

29 YoungTM,BlendinginIreland.Proc.Fert.Soc.N°255,April1987

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