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.
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.
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.
Where hopper bottom wagons are not available then flat bottom wagons may be employed but a Wagon Tippler will be required if the discharge is to be automated. Typical designs from Schade include the O-frame, C-frame and pivot-frame designs all supplied with various designs of indexer to automate the movement of the wagon and wagon rake eliminating the need to hold a shunter or switcher for the duration of the rake discharge.
Of course the wagon tippler may be supplied with the associated plate feeder or, where excavation depth may be limited, the Samson feeder offers significant advantages.From the road truck or railcar discharge the raw material or fuel may be conveyed into the storage hall and stacked by travelling stacker or from overhead tripper system all of which are offered by Schade along with the automation package for unattended operation.
Typical longitudinal storage solutions with travelling and luffing boom stacker plus a cantilevered boom style reclaimer recovering dissimilar materials from discrete storage bays or when handling the same material the circular storage offers a compact alternative with also the option of layered loading and blending using the Bridge Reclaimer system.
The boom type chain scraper reclaimer concept draws material from the inclined stockpile face and discharges to a collecting conveyor running parallel to the stockpile. The recovered material may be conveyed to silo storage or bunkers where it may be blended and delivered in controlled proportions to perhaps a milling system before processing.
For larger installations typically in such as Australia and South Africa central preparation plants draw raw materials from often a number of satellite mining operations for blending, washing and loading to trains for transfer to the port. Clearly the central prep-plant has an enormous advantage in that only one railroad is required clearly saving significant cost and enabling most efficient use of the rail network. However, material must be hauled from the mine sites to the prep-plant using a fleet of large dump trucks or more often road trains with multiple side tipping trailers. The intake of material from these road trains is a challenge since the trucks must be rapidly discharged and returned to the mine requiring high performance intake capacity and high holding capacity. Again the Samson Surface Feeder with D6 conveyor chains and rollers extends the required receiving area and offers a high holding capacity without the need for deep excavations and underground hoppers. Surface mounting is less polluting and offers easy access for maintenance and housekeeping.
In the complex market that exists today many minerals of vastly different handling characteristics must be transported from the mine site to processors, often on different continents, with often many logistics steps along the way.
And in addition to extracted minerals we also have to consider the movement of industrial by-products from such as power plant (Synthetic Gypsum) and steel works (Slag) which have become important assets in the global fight to reduce greenhouse gas emissions.
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