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QM August 2007 www.quarrymanagement.com 11

Full Steam Ahead at AngersteinFire-damaged wharf back on course following £2 million replant

Earlier this year CEMEX completed amajor reconstruction project at theirAngerstein Wharf marine aggregatesfacility on the south bank of the Thames,

just a few hundred metres downstream fromthe Millennium Dome in Greenwich, as part ofan ongoing, year-long, £60 million nationalinvestment programme spanning their entireUK business.Developed as a replacement for the former

Orchard and Barking wharves on the northside of the river, Angerstein Wharf wasoriginally established in 1991 by St. Albans

Sand & Gravel (subsequently part of the RMCGroup) to produce 10mm and 20mm gravelsand a single grade of sharp sand. The facilitywas constructed at a cost £12.5 million(including piling works etc) on freehold landthat had been acquired by the company sometwo years earlier. The recent £2 million replant at Angerstein

was required to bring the plant back onstream following a serious fire at the site inOctober 2004 (prior to CEMEX ownership) –an incident which began during routinemaintenance work when sparks from a ‰

Part of the new £2 million marine sand and gravel processing plant at Angerstein Wharf in London

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welding torch inadvertently set light to arubber lined pipe. The ensuing blaze quicklyspread to other parts of the plant, destroyingtwo screen houses together with associatedconveyor equipment and resulting in thecomplete cessation of processing operations atthe site.Despite this setback, new owners CEMEX

continued to service the wharf’s customersduring the subsequent demolition andclearance work by sourcing materialsexternally. In August 2005, some 10 monthsafter the fire, the situation was eased when a

fully mobile, 200 tonnes/h Powerscreen sandand gravel plant, supplied by DUO (Europe)plc, was installed at the site to provide astopgap processing capability.Operated on a double-shift (20h/day) basis,

this plant was more than capable of producing70,000 tonnes per month and proved to be ahighly effective interim solution to CEMEX’simmediate supply problem. Indeed, the plantwas so successful both commercially andoperationally that DUO (Europe) weresubsequently awarded a ‘one-stop-shop’contract for the supply and installation of the

Sand and gravel is broughtashore by an inclined conveyor

The new plant feedarrangement with the existingtripper conveyor and ‘as-dredged’ stockpiles in thebackground


replacement fixed plant at Angerstein.Whereas the original twin-line 750 tonnes/h

plant had been considerably over-complicatedin its design, and in reality never achievedmore than 450 tonnes/h, the new plant wouldcomprise a much simpler modulararrangement, again with twin processing linesbut this time with a nominal output capacity of400 tonnes/h. In contrast with the previousplant’s eight screens, single crusher, 19 conveyors, 28 pumps and seven staff, thenew plant would achieve similar end resultsusing just four screens, one crusher, 15 conveyors, one pump and four staff.Following the placement of concrete

foundation pads and the installation of mainswater and electricity supplies, DUOcommenced work on site in late December2006, with the main plant build taking placeduring January 2007. Operation of the adjacentmobile plant was maintained throughout thebuild phase to ensure continuity of supplies. The raw material processed at Angerstein

Wharf is obtained from licensed dredgingareas in the Thames estuary and EasternChannel by CEMEX’s Sand Fulmar and SandFalcon dredging vessels. An average of threeshiploads are landed at the wharf on a weeklybasis, each load comprising around 7,500 tonnes of sand and gravel. The as-dredged materials are known as GreenwichLight East, which largely comprises –70mmgravel with coarser sand, and North and SouthLowestoft, which largely comprises 10mmgravel and finer sand, respectively.The materials are unloaded from the self-

discharge dredgers at a rate of around 2,000 tonnes/h and deposited in a receptionhopper located at the end of Angerstein’s

mooring jetty. From here the material isbrought ashore by an inclined conveyor thatdischarges on to the site’s existing high-leveltripper conveyor system to create a 50,000 tonne capacity stockpile of as-dredgedmaterial from the two source areas. A 50/50 blend of the materials is collected

from the stockpiles by a Volvo L180E loadingshovel and fed to the new 400 tonnes/h twin-line processing plant via a 50-tonne capacityfeed hopper. This unit is equipped with 100mmgrid bars and a variable-speed feed belt, whichin turn feeds on to a 31m long x 800mm wideinclined conveyor. Rated at 400 tonnes/h andequipped with an Eriez permanent magnet, thisconveyor discharges the –100mm material intoa reception chute arrangement, which alsoaccepts a recirculated feed of crushed oversizematerial.From here the –100mm material is fed on

to a 20m long x 800mm wide 650 tonnes/hinclined conveyor that feeds into a two-waydischarge chute/boiling box arrangement,allowing either one or both processing ‰

Part of the new 400 tonnes/hprocessing plant, supplied andinstalled by DUO (Europe) plc

Left: One of the twoFinesmaster 200 sand plants

Below: The sand stockpileconveyor, with the temporaryPowerscreen mobile plant inthe background

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lines to be utilized. Material is sent forward totwo double-deck 20ft x 6ft Cedarapidshorizontal rinsing screens, supplied by DUO.Any oversize +70mm material is scalped off atthis point and sent to an adjacent groundstorage bay via a 13.4m long x 800mm widestocking conveyor, while the –6mm underflow(sand) content is flumed to two PowerscreenFinesmaster 200 sand plants. Dewatered sandfrom both Finesmasters is discharged on to a26m long x 800mm wide catenary conveyorrated at 280 tonnes/h, which in turn feeds onto a 24m long x 800mm wide powered radialstockpile conveyor. The minimal amount of

waste silt produced (around 2.5–3%) is flumedto the site’s existing treatment plant, whichincorporates a 10 tonnes/h Wemco belt press. At the same time, the –80mm +6mm

fraction from each rinsing screen is sentforward via a pair of 24m long x 800mm wideinclined conveyors. Rated at 260 tonnes/h,these conveyors feed two more 20ft x 6ftCedarapids horizontal screens, again suppliedby DUO. Material passing the top decks is fedon to a 30m long x 800mm wide stockingconveyor to produce a 20mm final productstockpile, while the material passing thebottom decks is discharged on to a 24m ‰

Oversize material isrecirculated via a Pegson1000 Automax cone crusher

The twin-stream plant isdesigned to produce sharpsand and 10mm and 20mmgravels


long x 800mm wide powered radial stockpileconveyor to produce a 10mm final productstockpile.Meanwhile, the –80mm +20mm oversize

material is delivered on to a 16m long x800mm wide reversible horizontal conveyor.Rated at 180 tonnes/h, this belt feeds on to a32m long x 800mm wide inclined crusher feedconveyor but, when necessary (eg duringcrusher maintenance), can be reversed to sendthe oversize to a ground stockpile via a 12mlong x 800mm wide stocking conveyor.Rated at 180 tonnes/h and equipped with an

Eriez permanent magnet and metal detector,the crusher feed conveyor discharges theoversize into a 50-tonne capacity crushersurge bin. A Siemens Multi Ranger level sensordetermines when to start/stop a Rotexvibrating tray feeder, which is used to choke-feed the Pegson 1000 Automax cone crusher.Crushed material is fed on to a 26m long x800mm wide inclined belt conveyor fortransfer back to the reception chutearrangement mentioned earlier, where it iscombined with the as-dredged feed material.The plant specification includes fully

galvanized heavy-gauge steelwork and guardingthroughout, remote greasing on all bearingsfor ease of maintenance, fully linked trip wiresdesigned to shut down the entire plantinstantaneously should any wire be activated,and multiple wash-down points for maintainingsite cleanliness. A moisture-reduction systemhas also been installed beneath the sharp sandstockpile to increase the rate of drying. Plantoperation is via a touch-screen, with fullstart/stop, alarm, history recording and faultdiagnostic capabilities. At any time the plantcan be run in full twin-line specification orwith one of the two processing lines shutdown. In its current configuration, Angerstein

Wharf is capable of delivering around1,400,000 tonnes of clean sand and gravel per

annum, when operating at full capacity. Alreadyfeaturing significant improvements over itspredecessor, the plant’s ‘future-proof’ design issuch that further modifications over time willallow it to keep pace with any significantchanges in demand over the next 25–30 years.Approximately 80% of current production is

supplied internally to CEMEX’s ready-mixedconcrete plants at Stepney, Canning Town,White City, Hendon and Kings Cross, with afleet of 26 tipper trucks operating out of thesite to provide the necessary transportation. Inaddition, the company’s newly commissioned120m3/h Liebherr Betomix concrete batchingplant, located on a site adjacent to AngersteinWharf, takes around 80,000 tonnes/year.Facilities at the site also include a 450 tonnes/hbarge-loading system, which is used for thesupply of washed sharp sand to CEMEX’sready-mixed concrete plant in Fulham. Looking to the future, CEMEX plan to

develop Angerstein’s sales to the open marketand are also looking to capitalize on theimpending Olympic Games and ThamesGateway developments. At its peak, work onthe Olympic facilities alone is expected torequire up to 9,000 tonnes of constructionaggregates on a daily basis. Althoughcompetition for a share of this market willundoubtedly be fierce, CEMEX believe theyare now in their best–ever position incentral/east London and north-west Kent, andsay their Angerstein, Northfleet and Dagenhamwharves form a triangle that will be ideallyplaced to supply aggregates and concretedirect to the heart of the Olympicconstruction sites via the river Lea.

AcknowledgementThe editor wishes to thank CEMEX forpermission to visit the site and, in particular,David Whitby, unit manager, and Glyn Richards,regional operations manager, for their help inpreparing this report.

The new CEMEX ready-mixedconcrete plant adjacent toAngerstein Wharf