Floculantes Información Praestol

7/25/2019 Floculantes Informacin Praestol

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Flo ccula nt s fo r a ll Applicat io ns

invo lving So lid /Liq uid Sepa ra t io n

PRAESTOL


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1. Introduction

2. Mode of Action

3. Properties

4. Production of PRAESTOL Solutions

5. Dosage Quantities

6. Method of Dosage

7. Operating Reliability and Accident Prevention

8. Storage

9. Packing

10. Examples of Use and Applications of PRAESTOL Flocculants

11. PRAESTOL

Product Range

11.1 Non-ionic and Anionic PRAESTOLProducts

11.2 Cationic PRAESTOL Products

11.3 Special Products

12. PRAESTOLTR Grades for Processing Potable Water

12.1 Product Range

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Contents Page

Ashland Deutschland GmbHEnvironmental and Process SolutionsFtingsweg 20, D-47805 KrefeldP.O. Box 10 04 52, D-47704 KrefeldPhone: +49 2151 38 3555Fax: +49 2151 38 [email protected]


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Anionic

Cationic

Charge characterNon-ionic

Supply forms

Granulates

Oil-free dispersions

1. Introduction

PRAESTOL products are organic, synthetic, high molecular flocculants based on polyacryl-

amide.

Non-ionic PRAESTOL flocculant types (formula 1) are technically pure polyacrylamides. Theyexhibit neutral (i. e. non-ionic) properties in aqueous solution.

Anionic PRAESTOL flocculants (formula 2) are co-polymers of acrylamide with increasing

proportions of acrylate groups, which give the polymers negative charges, and thus anionicac-

tive character, in aqueous solution.

Cationic PRAESTOL products (formula 3) are co-polymers of acrylamide with increasing

proportions of a cationic co-monomer. The cationic groups, which are thus introduced into the

polymer, have positive charges in aqueous solution.

Emulsions

PRAESTOL flocculants are available both as granular (solid) products and in liquid form as

water-in-oil emulsions, as oil-free dispersions and as aqueous solutions.

The granular products are white, granular, free-flowing, low-dust products with a grain size

up to 1.2 mm.

The water-in-oil emulsions are viscous free-flowing gel dispersions.

The oil-free dispersions are somewhat more viscous than the water-in-oil emulsions. This higher

viscosity does not imply any disadvantages for handling the products, i. e. the advantages of

the liquid products (handling, ease of dosage) are preserved. The oil-free flocculants show very

good solubility properties in water. While special attention must be given in water-in-oil emul-

sions to the solubility properties, the so-termed reversal behavior, the oil-free dispersions

mix with water immediately, i. e. without maturing time, and produce a ready-to-use solution

for dosage. The ready-to-use solutions are gel-free.


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Viscosities

pH values

* 1 dH = 1 (German) degree of hardness = hardness due to 10 mg of lime (CaO) in 1 l of water or 17.8 mg CaCO3in 1 l of water.

Charge exchangeDestabilisation

Surface potencial

Original suspension

Effectiveness

Product properties =mean values

Bulk density

2. Mode of Action

PRAESTOLflocculants incorporate reactive groups in aqueous solution, which have a strong

affinity to the surfaces of suspended colloids or very fine particles in aqueous suspensions or

slurries. According to the ionicity of the PRAESTOL types, interactions between them and the

solid particles are based on the formation of hydrogen bonds, as is the case with the non-ionic

polymers, or on electrostatic interactions and charge exchange, resulting in the destabilization

of the particle surface; the anionic (= negatively charged) and cationic (= positively charged)

PRAESTOL products act in this way. Destabilization and coagulation of a large number of

single particles leads to the formation of voluminous macro-flocs, which are easy to separate

from the suspension.

Thus the optimum effect of a PRAESTOL polymer is mainly determined by the surface po-

tential acting on the particle. These potentials are dependent both on the particle itself and on

the conditions in the environment, i. e. on the ionic strength of the water and the properties

resulting from this, such as pH value, electrical conductivity, hardness, surfactant content.

The most suitable PRAESTOL type for a particular application can be easily determined by

carrying out relatively simple preliminary tests. It is important that these tests are carried out

on the original suspension (solids and water), under the specified operating conditions (such

as temperature, turbulence, addition of other processing aids).

PRAESTOL products, as polymeric flocculants, are able to flocculate solid particles, colloids,

hydroxides and for example, bacterial substances. In the flocculated state, the solids can be

quickly and completely separated from the surrounding water. PRAESTOL flocculants are not

used to separate dissolved ingredients from water.

PRAESTOL polymers are effective in the pH range 1 to 14, depending on the particular typeinvolved. They are also effective in systems with low electrolyte concentrations, right up to

saturated salt solutions. Furthermore they cover the complete temperature range in which the

aqueous suspension is liquid, i. e. from approx. 0 C to 100 C.

3. Properties

The numerical values for the product properties, which are given in the product overview tables

are mean values, which may vary in individual cases.

The bulk density is measured using a running out breaker. This property must be taken into

consideration when designing storage tanks and feeding equipment for dissolving plants basedon volumetric dosage.

Viscosities are determined with the Brookfield viscometer at 20 C. Solutions for viscosity

measurements are prepared in distilled or de-ionized water. The viscosities quoted thus represent

the typical value, for a particular concentration of product, which has to be considered when

designing stirrers, pumps, measuring sections etc.

The solutions for determining the pH value were prepared with Krefeld tap water (approx.

25 dH*, pH value approx. 7, electrical conductivity approx. 600 S/cm). The pH values must be

taken into account when selecting the material for dissolving and dosing equipment.


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Molecular weights

Ready-to-use solution /Stock solution

Granulates

Dispersers

The molecular weights of the anionic products are between 6 to 30 million, whereby as a general

rule the molecular weights of the granulates in the 23 series are in the lower range and those of

the granulates in the 26 series are in the upper range. The molecular weights of the non-ionic

and anionic emulsion grade polymers are in the same order of magnitude.

The molecular weights of the cationic products are about 6 to 20 million; usually granulates of

the 6 series are in the lower range and granulates of the 8 series as well as emulsion polymers

in the upper range. Cationic solution polymers have a molecular weight of approx. 1 million.

4. Production of PRAESTOLSolutions

PRAESTOL flocculants are used in highly diluted aqueous solutions (e. g. 0.1 % by weight).

To keep the dissolving time low, it is recommendable when producing the ready-to-use solution

to use a concentrated stock solution (e. g. 0.5 % by weight) first, which can be diluted later to

the required application concentration. Alternatively, the ready-to-use solution can be prepared

immediately at the desired low concentration but a longer dissolving time must be taken into

account here. Tested and proven dissolving equipment is available for preparing solutions. Both

the stock and ready-to-use solutions require a maturing time, during which time the solution

should be kept gently agitated.

In producing aqueous solutions of PRAESTOL granulates, the following points must be

observed:

When adding the PRAESTOL granulates, it is important that each single particle is

individually wetted by the water. It is therefore recommended to add the granulates

slowly into the turbulent water.

It is particularly recommended to use an auxiliary unit, e. g. a disperser.

See our special information for details.

Emulsions

The subsequent dissolving procedure is aided by a turbulent agitation of the water

(stirrer, compressed-air swirling).

The dissolving time depends on the product type and on the quality and temperature

of the solution water. It usually takes about 60 minutes for the product to develop its

effectiveness completely. This should be taken into account when designing the dissolving units.

The production of aqueous solutions from PRAESTOL emulsions can be done by carefully

pouring the product into the vigorously stirred solution water or by use of special mixing units

(in-line mixers).

To guarantee developing of the full effectiveness of the product, sufficient time

should be allowed for dissolving. A dissolving time of 5 to 20 minutes is sufficient,

depending on the concentration of the solution. With increasing concentration of

the solution the required dissolving time will decrease.

Automatic dissolving units are used specially for the continuous, operational use

of PRAESTOL emulsions.


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Fig. 4:Dependence of the rate of sedimentationon the dosage quantity for suspensionswith varying solids content

Suspension A: solids content 36 g/lSuspension B: solids content 64 g/l

5. Dosage Quantities

Owing to the very different flocculating properties of the sludges to be dewatered, the required

dosing quantities can only be determined by laboratory tests or directly by carrying out plant

trials in each individual case.

In the case of mechanical sludge dewatering of mostly inorganic solids on rotary vacuum

filters, centrifuges, belt presses, chamber filter presses, PRAESTOL flocculants can increase

the output with almost completely dry cakes. The required dosing quantities lie between 80

and 300 g/t dry substance dependent on the dewatering unit.

In mechanical dewatering of mostly organic sludge on (heavy-duty) centrifuges, belt presses,

chamber and membrane filter presses, cationic-active PRAESTOL flocculants are used negating

the need for inorganic agents such as metallic salts or lime. The addition rates of polyelectrolyteare normally between 2 and 8 kg/t dry substance.

When used to accelerate the rate of sedimentation or as a clarifying agent in settling tanks, a

dose rate of 1 to 20 g/m3of the suspension to be clarified is normally sufficient.

Higher dose rates may be necessary:

Where there is a high solids content in the suspension

With increasing fineness of the suspended solids

Where the suspension has a low temperature

Figure 4 shows the relative dependence of the sedimentation speed obtained with flocculationon the different solids contents of the respective suspension.

Aqueous solutions

Feeding and dosing

PRAESTOLproducts in the form of aqueous solutions are diluted by stirring and mixing to

the required concentration for use. A dissolving time is not necessary.

Excessively fast stirrers should not be used to produce PRAESTOL stock solutions and dur-

ing their further dilution. The stirrers maximum circumferential speed should be 10 m/s as

otherwise the effectiveness of the highly-molecular polymer will be reduced by excessive

shearing of the chain lengths.

Progressive cavity pumps and not centrifugal or gear pumps should be used to feed and dose

the PRAESTOL solutions.

Stock solutions

Sludge dewatering ofinorganic solids

Organic sludge


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Even distribution

Type and point of dosage

Non-corrosive

Danger of slipping

6. Method of Dosage

As the dosage quantities of synthetic flocculants are low, an even distribution of the PRAESTOL

solution in the suspension to be treated is a prerequisite for its optimum effect.

This even distribution can be achieved by:

Diluting the flocculant solution as much as possible

The corresponding duration and intensity of the mixture of the flocculant solution

with the suspension or thickened sludge

Multiple dosage: The total quantity of flocculant solution required is added to the

suspension to be treated at different points. In many cases, multiple dosage helps toimprove the purification of the suspension being treated.

The advantageous type and the right point for adding the PRAESTOL solution to the suspension

or sludge depends on the properties of the suspension, the type of clarification or dewatering

process and the operating result required, e. g., fast rate of sedimentation, very good clarifica-

tion, high flocculation stability.

The following points apply:

A type of dosage of the flocculant solution to the suspension or sludge must be

selected which will ensure that the solution is distributed evenly.

A dosage point must be selected which will ensure sufficient reaction time betweenthe flocculant and the solid particles to be flocculated.

Flocs already formed should have the opportunity of uniting to form larger entities.

On the other hand, the destruction of the flocs by means of gravitational forces,

e. g. because of unfavorable flow conditions, should be avoided.

7. Operating Reliability and Accident Prevention

Our experience has shown that PRAESTOL solutions are non-corrosive in contact with materi-

als used for tanks and pipes, such as fiberglass, plastics, plastic-lined materials and stainless

steel.

Owing to the properties of organic solvent in the liquid products, plastic containers (pipes,

pump components) coming into contact with the undiluted product must be made of solvent-

proof material.

Scattered granular product on a wet floor, liquid product or solution which has been spilt onto

the floor, will cause slipping.

In this case the solid product or solution can be soaked up with absorbent material, e. g. saw-

dust, sand etc. and disposed of.


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Water sensitivity

Homogenization

Storage temperature

8. Storage

Highly-molecular flocculants like PRAESTOLare basically sensitive to moisture, such as

condensation, splashes and humidity. Contact with water (droplets) can lead to local formation

of knots and lumps. The product should therefore be stored in dry, closed containers, protected

against moisture (bags, big bags, containers).

After prolonged storage emulsion grade polymers might tend to separate into layers. After

homogenization by intensive stirring, pumping or re-circulation by gas injection (nitrogen,

air) the products may be re-used without any loss in quality.

The storage temperature should not exceed 40 C for long periods.

The product viscosity of emulsion grade polymers increases at low temperatures. The product

can no longer be pumped below -10 C. After warming up to approx. 8 to 10 C and homo-

genization, however, the product can be reused without any loss in efficiency.

Storage stability under correct storage conditions:

Granulates in original packing : at least 12 months

Emulsions in original packing: at least 6 months

Oil-free dispersions: at least 3 months

The storability of the stock solution and ready-to-use solution depends on the individual product.

We refer you to the corresponding PRAESTOL technical leaflet.

9. Packing

Granular products: Paper valve bags shrink-wrapped on pallets

Big bag

Liquid products: Drum

Container

Road tanker

Storage stability


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Fields of Application

Drinking Water

Industrial Water

Mining (coal / ore / salts) Wash water

Filtration of concentrates Flotation tailings Flotation pulps Acidic brines Alkaline brines

Chemical Industry Pigments (inorganic) Pigments (organic) Leaching liquors Biotechnological suspensions

Metal Producing and Metal Processing Industry

Paper Industry Retention/White water and Waste water

Waste Water (industrial, municipal) Waste water, also after neutralization

Sludge Dewatering Raw sludge Digested sludge Surplus sludge (also thickening,

centrifuging or flotation)

Non-ionic

slightly medium strongly slightly medium strongly

Anionic Cationic

10. Examples of Use and Applications of PRAESTOLFlocculants

To select the optimum product for your process from our product range, please see the

supplementary information Laboratory Tests with PRAESTOL Flocculants.


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Polyacrylamides

Very low residualcontent of monomeracrylamide

1 Letter by WHO dated January 21, 19942 DWI, London: Water Industry Act 1991: Section 69

Water Supply (Water Quality) Regulations 1989

Water Supply (Water Quality) (Amendment) Regulations 19913 DIN EN 1407 and EN 14104 DWI, London: Regulation 25 Letter 2/2002 of November 7, 2002

12. PRAESTOLTR Grades for Processing Potable Water

The synthetic polyelectrolytes which are now increasingly used in the preparation of potable

water are mainly water-soluble polyacrylamides.

A prerequisite for the use of polyacrylamides for this purpose is that they should have a very

low residual content of monomer acrylamide.

The World Health Organization (WHO) recommends limiting the amount of monomer acryl-

amide in drinking water to less than 0.5 g/l. Thus, in consideration of all safety measures

in a daily consumption of 2 liters of drinking water the total amount of monomer acrylamide

should not exceed 0.017 mg per kilogram of body weight per day.1

A residual monomer content of 0.05 % by weight (500 ppm) and a dosage of 1 mg/l (1 ppm), as

prescribed by the Food and Drug Administration (FDA) for the USA (CFR 40, 141.111), are

already within this limit.

Regulations in other countries reflect these requirements:

Germany

In Germany the use of PRAESTOL TR grades for the preparation of potable water is controlled

under the Foodstuffs, Consumer Goods and Animal Feed Code (Lebensmittel-, Bedarfsgegen-

stnde- und Futtermittelgesetzbuch, LFGB). The LFGB requires that with appropriate use of

auxiliary agents in the processing of potable water these agents must, except for technically

unavoidable and technologically inactive residues, be removed from the potable water. Whenproperly used, the PRAESTOL TR grades meet these requirements, which are set out in the

LFGB.

In keeping with 11 of the 2001 Drinking Water Act, approved conditioning agents appear

on a list published by the Federal Ministry of Health and Social Security (Bundesministerium

fr Gesundheit und Soziale Sicherung, BMGS). Only anionic and non-ionic grades with a

residual monomer content of below 0.025 % at a polymer dosage of 0.4 mg/l (DIN EN 1407)

are approved for use.

Great Britain

As of December 2003, the amount of monomer acrylamide may not exceed 0.02 %. The

quantity of the polymer dosed may not exceed 0.5 mg/l.2,3,4

European Union

The standards EN 1407 and EN 1410 were adopted by CEN (European Standards Committee)

on March 23, 1998. They prescribe polyacrylamide for conditioning potable water with a re-

sidual monomer content of less than 0.025 % acrylamide with a polymer dosage not to exceed

0.4 mg/l. Both standards are also valid for Germany.

These standards, as well as those for Germany and Great Britain, are in compliance with EU

guidelines 98/83/EG concerning the quality of water for human consumption (EU Drinking

Water Guideline, limit: 0.1g/l in the drinking water).


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International certifyingorganizations

USA

Certification is awarded by the National Sanitation Foundation International (NSF) and con-

forms to the requirements of Standard 60 Drinking Water Treatment Chemicals - Health

Effects. A residual monomer content of < 0.05 % by weight at a dosage of not more than

1 mg/l is prescribed.

USA: National Sanitation Foundation International (NSF),Ann Arbor, Michigan

GB: Department for Environment, Food and Rural Affairs,Drinking Water Inspectorate (DWI)London

Approved for use are polymers which comply with the standards

DIN EN 1407 and EN 1410. Packaging is appropriately labeled.5

PRAESTOLTR Grades

PRAESTOL TR grades are produced using a special method and every production batch is very

carefully monitored with regard to the residual content of monomer acrylamide.

For every consignment of our PRAESTOL TR product types we guarantee a residual monomer

content of < 0.02 % (by weight) of monomer acrylamide (with reference to the polymer).

On special request we can supply the relevant certificate of analysis with every consignment

of PRAESTOL TR flocculants.

The following institutes have issued certificates declaring the PRAESTOL TR grades (shown

in the table)to be safe for use in potable water preparation:

National Sanitation Foundation International, USA

ANSI/NSF Standard 60 Drinking Water Treatment Chemicals - Health Effects

All anionic and cationic PRAESTOL TR flocculant types are certified.

Department for Environment, Food and Rural Affairs,

Drinking Water Inspectorate, Great Britain All anionic and cationic PRAESTOL TR flocculants types have been approved

for use in conditioning drinking water.

Federal Ministry of Health and Social Security, Germany

Approval for anionic and non-ionic PRAESTOL TR flocculant types.

Further fields of application for PRAESTOL TR flocculants for water treatment are lime water

production, water works sludge treatment and phosphate removal.

5 DWI, London: Regulation 25 Letter 11/2000 of September 29, 2000


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2500 TR non- 650 200 50 7 1 - 7 USAionic Great Britain

Germany

2515 TR weakly 650 3000 400 7 7 - 10 USA anionic Great Britain Germany

2530 TR medium 700 4000 500 7 6 - 10 USA 2540 TR anionic 700 5500 600 7 6 - 13 Great Britain

Germany

650 TR medium 650 700 65 7 1 - 14 USAcationic Great Britain

851 TR weakly 650 600 50 7 1 - 14 USA

cationic Great Britain

DW = De-ionized water

TW = Krefeld tap water: approx. 25 dH (German) degree of hardness, electrical conductivity approx. 600 S/cm, pH value approx. 7

12.1 Product Range

PRAESTOLTR Grades for Processing Potable Water

PRAESTOL Ionic Bulk Viscosity pH Effective in Approved inCharge Density the pH Range

0.5 % by wt. 0.1 % by wt. 0.1 % by wt.DW DW TW

approx. approx. approx. approx. kg/m3 mPa.s mPa.s

All statements, information and data presented herein are believed to be accurate and reliable but are not to betaken as a guarantee, express warranty or implied warranty of merchantability or fitness for a particular purpose,

or representation, express or implied, for which seller assumes legal responsibility, and they are offered solely

for your consideration, investigation and verification. Statements or suggestions concerning possible use of this

product are made without representation or warranty that any such use is free of patent infringement and are not

recommendations to infringe on any patent.

Ashland Deutschland GmbHEnvironmental and Process SolutionsFtingsweg 20, D-47805 KrefeldP.O. Box 10 04 52, D-47704 KrefeldPhone: +49 2151 38 3555Fax: +49 2151 38 [email protected]

egisteredtrademark,

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