Solutions for the Handling of Bulk Solids in the Supply Chain
Today raw material transport over great distances is a standard procedure in the minerals and metals industries. Industrial minerals are now shipped across the globe in vast volumes demanding efficient logistics to minimise both the cost of transportation and the carbon footprint. Especially under these circumstances, ingenious solutions for the handling of material during storage and transshipping can help save the pivotal dollar.
(ed. WoMaMarcel - 25/6/2015)
Clean Loading and Unloading
Similarly at the port of entry mobile discharge equipment, based often today on grab fitted mobile harbour cranes, is the preferred solution allowing the berth to be used for multiple cargoes including bulk, container and break-bulk. However, for bulk discharge of dusty cargoes due consideration must be given to environmental pollution from wind-blown fugitive dust created by material falling free from the grab. Free falling material separates into particles and dust is free in the air within the material stream, dust released in this way is readily disturbed by air movement including side winds. The only solution to control the dust is to control the material free fall into a suitable hopper. However, as the material falls from grab into the receiving hopper air is displaced which collects the free dust particles and the dust laden air is ejected from the hopper at high speed.
The same problem applies to the loading of the tipping trucks where again air is displaced and any uncontrolled dust is ejected from the truck body. If uncontrolled combining both the dust generation from the grab discharge and from the truck loading is a double whammy and the result will be billowing clouds of dust from the discharge operation causing considerable pollution and being a hazard to the health of all working in the vicinity.
The solution is the Eco Hopper concept comprising both dust controlled grab discharge and dust controlled truck loading using a concentric chute with dust extracted through the annulus ring. Controlling dust from the grab requires a two pronged attack using the Flex-Flap system to minimise the flow of displaced air from the hopper and also a high capacity dust extraction and filtration system to both clean the displaced air and create a net air flow into the hopper from the grab discharge. To mitigate the effects of side winds it is essential the grab discharges within a shroud extending around 2 metres above the Flex-Flap and then the dust laden air from the shroud can be drawn into the hopper bowl to be cleaned by the dust extraction equipment.
Flexibility at the Berth
In most applications a quayside stockpile is not acceptable and therefore the bulk cargo must be moved off the berth to a remote storage area using either a fixed conveyor system or, as illustrated herein, by tipping trucks operating on a merry-go-round basis. Using mobile Eco Hoppers and truck transfer the berth maybe cleared of equipment completely after the bulk vessel is discharged freeing the berth for other port operations.
In many situations the mobile option for both ship loading and discharge offers clients a viable alternative to permanent fixed installations and in today’s market is an attractive flexible investment.
Exporting copperconcentrate from Peru direct from truck to ship.
Intake and Storage at the Process Plant
Whether shipped by rail, barge or deep sea vessel the final link in the logistics chain is the intake and storage of these materials at the process plant. From the rail or road intake facility typically the bulk mineral will be conveyed to local storage facility such as a dome or silo system. For larger volumes a horizontal storage system including perhaps blending where material may be supplied from a range of sources may be appropriate and blended into a homogeneous output.
The Samson Surface Feeder concept offers the most economical and environmentally friendly solution for raw material or fuel import from tipping trucks. Being surface mounted of course saves on civil works but also reduced the uncontrolled free fall with associated displaced air and as a result dust generation is mitigated at source saving on expensive dust plant and reducing operating costs.
Of course the same equipment may be used for under rail discharge of hopper bottom rail wagons and in this case similar arguments apply in that the excavation depth is reduced saving civil works costs and reducing material free fall with a corresponding reduction in dust generation.
The same general arguments for dust control is applied at the Eco Hopper and the Samson feeder based on mitigation at source to save on capital and operating costs.