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)
The Mineral Logistics Chain
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. The Aumund Group has developed a range of bulk handling solutions at each link in the mineral logistics chain allowing the operator to take maximum advantage of any combination of truck, rail, barge and deep sea shipment.
At the mine site the fundamentals of extracting the raw mineral has not changed in centuries, the rock is blasted from the face and loaded to trucks to be taken to a central primary crusher and then conveyed to a secondary crushing and screening station to be stockpiled before export. The apron plate feeder is first in the chain, handling the as-mined lumpy rock, providing a controlled feed rate to the primary crusher with typically an electrical interface to match the feeder to the crusher performance and avoid over-feeding. The feeder design is based on tracked vehicle type chains and supported on close pitch matching rollers plus central skids to absorb impact loads. Each plate is made in two overlapping parts with milled edges ensuring the plates articulate at the head and tail sprocket and an effective seal maintained to reduce risk of spillage between the plates. Available with a total plate thickness of 80 mm and maximum plate width of 3 metres these machines may be matched to the largest haul trucks for handling rates to 3,000 tons per hour.
Of course the blast-haul-crush concept with a remote central fixed primary crusher is expensive to operate when the hauling distance increases. One solution is to bring the crusher to the face thus eliminating the intermediate handling by haul truck. Samson pioneered the concept of mobile link conveyors used with a track mounted mobile crusher and hydraulic excavator such that all the equipment operating at the face remained mobile and could be moved back for blasting.
Self propelled mobile link conveyors for a track mounted face crusher.
From the link conveyors the sized material may be conveyed on conventional fixed or semi-permanent field conveyor equipment to the secondary crusher and final screening station and stockpile. Whilst the link conveyor solution eliminates all truck haulage there is no doubt that for short distances the flexibility of haul trucks is attractive for the operator.
Suface Feeders in Mining Applications
Since the 1970s Samson have evolved their Samson Surface Feeder also into the mining industry finding application as a mobile feed point to receive as-mined rock from articulated dump trucks and deliver to an ongoing belt conveyor incorporating an integral sizer to bring the material down to a manageable size for economic long haul conveying. In this manner of operation the sizer and feeder combination may be moved easily along the length of the conveyor to bring the feed point as close as possible to the work face, blasting permitted. The work face therefore runs parallel to the field conveyor and when the workable length of the field conveyor is exhausted the complete package may be moved sideways on the lateral sledges towards the face again and the process repeated. This is a typical example of blending the best attributes of truck and conveyor haulage to achieve the least operating cost and minimum carbon footprint.
Expanding this concept Samson have recently commissioned three of their new wheeled Material Feeders in a large mining operation in Southern Africa handling as mined rutile sands delivered by ADT achieving an average loading rate of around 1300 tons per hour per feeder. Based on the Berco “SALT” (Sealed And Lubricated Track) chains type D6 these feeders are able to operate reliably under extreme conditions handling highly abrasive ore.