Feeding, Conveying & Storage

Bulk Materials HandlingLogistics solutions from themine or quarry to the processing plant

In years past the location of a mineralprocessing plant was generally governedby the availability of raw material and

fuel, and the market for the finished goods.Over time, however, this link has effectivelybeen broken with the raw material and fuelsources often on different sides of the world.Industrial minerals are now shipped across

the globe in vast volumes, demanding efficientlogistics to minimize both the cost oftransportation and the carbon footprint.Aumund Group have developed a range of bulkhandling solutions from the mine site to theprocessing plant, allowing operators to takemaximum advantage of any combination oftruck, rail, barge or deep-sea shipment.Figure 1 shows an ungeared (ie without

deck cranes) Panamax-size vessel beingdischarged by a grab-equipped mobileharbour crane to an Eco-Hopper and then tostandard road tipper trucks for onwardmovement to local storage or direct to theprocessing plant. In this particular case, it iscement clinker that is being imported, but itcould equally be any mineral or concentrate.At the mine or quarry site, the

fundamentals of extracting raw mineralshave not changed in centuries; the rock isblasted from the face and loaded to trucks tobe taken to a central primary crusher and thenconveyed to a secondary crushing andscreening station to be stockpiled beforedespatch/export.

Fig. 1. Mineral import from Panamax ships

Figure 2 shows an Aumund type BPB-SFplate feeder receiving as-mined rock. Theapron feeder provides a controlled feed rateto the primary crusher with, typically, anelectrical interface tomatch the feeder to thecrusher performance to avoid over-feeding.The Aumund feeder design is based on

tracked vehicle type chains with a rupturestrength up to two times 3,600kN (type D9),supported on close-pitch matching rollersplus central skids to absorb impact loads.Each plate ismade in two overlapping parts

with milled edges, thereby ensuring theplates articulate at the head and tail sprocket,

while an effective seal ismaintained to reducethe risk of spillage between the plates (fig. 3).Available with a total plate thickness of80mm and maximum plate width of 3m,thesemachines can bematched to the largesthaul trucks for handling rates of up to 3,000tonnes/h.However, the blast–haul–crush concept

with a remote, central, fixed primary crusheris expensive to operate when the haulingdistance increases. Trucks are expensive toown, evenmore expensive to operate and havea very high carbon footprint.One solution is to bring the crusher to �

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Fig. 2. As-mined rock intake

Fig. 3. Aumund BPB-SF plate feeder

the face, thus eliminating intermediatehandling by haul truck. B&W MechanicalHandling Ltd, part of the Aumund Groupsince 2002, pioneered the concept of mobilelink conveyors used with a track-mountedmobile crusher and hydraulic excavator, suchthat all the equipment operating at the faceremained mobile and could be moved backduring blasting.Figure 4 shows a mobile link conveyor

installation where the mobile primary facecrusher is equipped with an integral screenand rejects-handling system, ensuring thefinal maximum material size is controlledwithin close limits.From the link conveyors, the sizedmaterial

may be conveyed by conventional fixed orsemi-permanent field conveyor equipment tothe secondary crusher and final screeningstation and stockpile.While the link conveyor solution eliminates

all truck haulage, there is little doubt that forshort distances, the flexibility of haul trucksis still attractive for most operators.Figure 5 shows a Samson surface feeder

integrated with a twin-shaft rotary sizerwhich forms a mobile feed point for amoveable overland conveyor system. Figure6 shows the field conveyormounted to sledgerunners which also carry the rail-mountedsizer.In this operation, the sizer and feeder

combination may be moved easily along thelength of the conveyor to bring the feed pointas close as possible to the working face. Theworking face therefore runs parallel to thefield conveyor and, when the workable lengthof the field conveyor has been exhausted, thecomplete package can be moved sidewaystowards the face on the lateral sledges andthe whole process is repeated.This keeps the haul length for the trucks to

a minimum; in this particular applicationhandling limestone, the system is able toachieve a performance rate of up to 800tonnes/h using only two articulated trucks.For economic conveying, the sizer reduces

the as-mined and loaded material from,typically, 800mm down to 150mm to beconveyed overland to a cement plant severalkilometres distant. With complex highwaysbetween the mine and the plant, haulage bytruck would have been difficult, thus addingto the attraction of long-distance conveyorhaulage. This is a typical example of how thebest attributes of truck and conveyor haulagehave been combined to achieve the leastoperating cost andminimum carbon footprint.Where the mine or quarry is close to the

processing plant, that is the end of theexternal logistics story, but inmany operationsthere is a large disconnect between theextraction site and processing plant requiringcomplex logistic operations in between.Where distances permit, truck haulage is

generally the most flexible option and in thissituation Aumund’s Samson surface feedersolution is an attractive option for the intakeof raw material. The Samson unit combinesthe benefit of a wide apron-plate feeder with

the cleanliness of a belt system, allowingmaterial to be received direct from truckswithout the need for deep underground pitsor hoppers.Figure 7 shows a Samson 800-Series

feeder receiving –25mm crushed limestoneat a power plant in the US. The limestone issourced from a local quarry some 10 miles

distant then further crushed andmilled on sitebefore making the slurry used for flue-gasdesulphurization.Figure 8 reveals that the equipment is

completely surface-mounted, including theongoing conveyor system taking the limestoneto a ground storage facility, and shows howthe Samson has a deflected chassis allowing

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Fig. 4. Mobile link conveyors

Fig. 5. Integrated mobile feeder and sizer

Fig. 6. Sledge/rail-mounted conveyor/sizer

Feeding, Conveying & Storage

the intake section to be near horizontal, thussimplifying the truck interface.Where the mine and processing plant are

in the same locality and both are either railconnected or close to suitable sidings, haulageby rail is by far the better solution, beingmoreeconomical and much less polluting with avery low carbon footprint. At the mine siterailcars can be loaded simply using a silo andloading chute system mounted to a suitablesupport structure above the rails.However, many sites are not directly rail

connected although theremay be rail sidingsclose by. In this situation the Stormajormobile loader, developed by B&W, offers asolution by allowing railcars to be loadeddirect from road trucks at an existing railsiding without the need for fixed plant orinfrastructure.Figure 9 shows a Stormajor providing a

railcar loading facility for a silica sand quarrynear Paris. The sand is trucked from thequarry to the siding some 20miles away, andthen loaded on to the stationary traincomprising around 20 railcars. The railcars aredelivered by locomotive in the morning,loaded during the day and collected in theevening.Figure 10 shows amore recent installation

at Poznan, in Poland, where basalt rock isdelivered to the Stormajor by articulateddumptrucks and loaded at a rail siding closeto the mine. In this particular case theStormajor (which is clad in flexible PVCsheeting tominimize dust escape) loads flat-bottom railcars using the radial boom feature,which includes a rotating trimming chute, toaccurately place the material.Delivery by truck is a temporary solution

pending installation of link conveyors and isa good example of how mobile loadingequipment can be used to take advantage ofa short-termmarket position; in this case theStormajor was delivered only 13 weeks afterorder placement, providing a genuine fast-track solution.Likewise, the Stormajor can be utilized for

the loading of barges formaterial distributionvia inland waterways, as illustrated in figure11. In this operation gabbro rock is delivered

to the lakeside from an adjacent quarry andloaded on to barges of around 5,000dwt fordistribution to Moscow and St. Petersburg.

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The equipment operates on a simple berthusing the long cantilevered outloading boomon the Stormajor to load the barges �

Fig. 7. Limestone intake to a power plant Fig. 8. Surface-mounted feeder and conveyor

Fig. 9. Stormajor mobile loader for railcars

Fig. 10. Stormajor loading rock in Poland

moored just offshore in deeper water, thusavoiding costly dredging and an expensivepermanent concrete dock.B&W Mechanical Handling Ltd pioneered

the concept of direct loading from truck torailcar, ship or barge. Figure 12 shows an earlysystem for exporting marble chips from theport of Marina di Carrara, in Italy,incorporating a Samson surface feeder anda mobile loading boom for delivery intoHandysize vessels.Whether shipped by rail, barge or deep-sea

vessel, the final link in the logistics chain isthe intake and storage of these materials atthe processing plant.Figure 13 shows a typical railcar intake

facility where hopper-bottom railcars aredischarged to an underground hopper andfeeder. A typical hopper/feeder combinationis illustrated in figure 14, where an Aumundtype PKF armoured chain feeder is employedto provide a controlled discharge rate to theongoing conveyors. Comprising scraperbars mounted to round link chains (fig. 15),this is a well established and proven solutionwhich has the advantage of being fullyenclosed and thus dust-tight and spillage-free. For underground installations cleanoperation is essential to minimizehousekeeping costs in difficult-to-accessareas.

In addition to underground feeders andassociated conveyors, a typical packagewould include an enclosure building with theoption of comprehensive dust-collectionequipment, depending upon the materialhandled and the sensitivity of the location.From the rail or road intake facility the bulk

mineral will, typically, be conveyed to alocal storage facility, such as a dome or silosystem. For larger volumes, a horizontalstorage system, perhaps including a blendingfacility where material may be suppliedfrom a range of sources, may be appropriate.Schade (Aumund Group) offer a range of

Fig. 11. Stormajor loading gabbro to barges on Lake Onega (Russia) Fig. 12. Truck to ship with mobile shiploader

Fig. 13. Rail intake with dome storage

Fig. 14. Under-rail hopper and feeder Fig. 15. Aumund PKF armoured chain feeder

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storage systems based on travelling stackersand chain scraper type reclaimers forautomated operation.Figures 16 and 17 show a typical

longitudinal storage solution with travellingand luffing boom stacker, plus a cantileveredboom style reclaimer recovering dissimilarmaterials from discrete storage bays.The boom-type chain scraper reclaimer

concept draws material from the inclinedstockpile face and discharges to a collectingconveyor running parallel to the stockpile.The recovered material can be conveyed tosilo storage or bunkers where it may beblended and delivered in controlledproportions to, for example, a milling systembefore processing.For more efficient blending at the storage

facility, the bridge reclaimer system shownin figure 18 offers true homogenization,producing a reliable and consistent materialspecification for the process plant.Both boom-type and bridge-type

reclaimers may be supplied in a circularformat with the option of a lightweight domeenclosure. This is the most economicalstorage solution in terms of both totalcapital cost and plant footprint.In most processing applications, at some

point in the handling systems material isstored in silos of either concrete or steelconstruction. To raise the bulk mineral to thestorage silo the Aumund type BWZ centralchain bucket elevator (fig 19) has proven aneffective solution with around 2,500installations worldwide.Vertical elevation minimizes the plant

footprint and the system is totally enclosedwith no risk of dust escape or materialspillage. The elevator plus feeder equipmentcan be integrated with a package for roadintake, as shown in figure 20, or for rail intakeas shown in figure 13.The equipment illustrated for intake from

rail is based on the use of hopper-bottom orside-door self-discharge railcars where thematerial falls naturally, under gravity, to ahopper below. However, not all countrieshave a sufficient supply of such railcars, asillustrated in figure 21, which shows a trainwith a combination of new hopper railcarsand old flat-bottom types.Obviously, the hopper-bottom cars are

easy to discharge but flat-bottom cars willneed manual excavation, a time-consumingand expensive process that can slow theoperation considerably.

Feeding, Conveying & Storage

Fig. 16. Longitudinal storage boom stacker Fig. 17. Cantilevered boom reclaimer Fig. 18. Circular storage and blending bed

Figure 22 shows an Aumund railcar tipplerinstalled at a Polish port, which handles flat-bottom railcars by clamping them in thetippler frame and rotating them to dischargethe contents to a hopper and feederbelow.In the complex market that exists today,

many minerals of vastly different handlingcharacteristics must be transported from themine or quarry to the processing site, oftenwith many logistical steps along the way.In addition to extracted minerals, it is

necessary to consider the movement of

industrial by-products, such as syntheticgypsum from power plants and slag fromsteel works, which have become importantassets in the global fight to reducegreenhouse gas emissions.This article demonstrates some of the

logistics challenges to be found along the wayand provides examples of how thesechallenges have beenmet with ingenious andeconomical solutions in terms of capital andoperating costs, and carbon footprint.For further information visit:

www.aumund.com

Fig. 19. Aumund central chain bucket elevator Fig. 21. Combination of hopper-bottom and flat-bottom railcars

Fig. 20. Vertical elevation to silo storage

Fig. 22. Aumund railcar tippler

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