Uranium Project Gets Fast Turnaround on its Ore Recycling Equipment Order
Earlier this year Langer Heinrich Uranium, situated 85 km from Swakopmund in Namibia, found that it needed to process a stockpile of high grade recycle material that had previously been stockpiled, as the material could not be effectively sized in the existing attritioner plant. The mine turned to Rex Quip, Pilot Crushtec’s Namibian dealer, for assistance to efficiently produce -2 mm material from ore that ranged in size from -75 mm to +10 mm.
Pilot Crushtec, a South African supplier of crushing, screening and material handling equipment,reports that it was able to assist the mine with quick delivery. “What clinched the deal for us was the fact that we had the equipment the mine needed readily available, so it was just a matter of weeks before the plant was dispatched to site,” explained Wayne Warren, Pilot Crushtec’s manager for Rex Quip, in Namibia.
Lionel Coetzee, senior metallurgist at Langer Heinrich Uranium, confirms this: “The plant was delivered in record time—around three weeks—which was refreshing. Since then it has been working satisfactorily.” At a purchase price of R3 million ($335,000), Pilot Crushtec supplied a complete modular crushing plant, mounted on skids for easy relocation: a GFH560 grizzly feed hopper, a MJ1252 modular jaw crusher, an AC07 vertical shaft impact (VSI) crusher, a DD2412 screen, and six 600-mm-wide conveyors with slewing capability.
“I must mention that when we arrived to commission the plant, in the middle of the desert, we found that it had rained so much that the whole plant area was flooded,” noted Pilot Crushtec’s Wayne Warren. “Usually we have to consider the very dry and windy conditions, so this was quite unexpected.”
“Several ’tweaks’ are presently being implemented in an attempt to maximize the efficiency of the plant,” said Lionel Coetzee. In addition to this, a wet-screen process may be introduced to further increase production and to assist with the conveying of the crushed product to the main processing plant.
According to a recent project update issued by the mine’s owner, Western Australia-based Paladin Energy Ltd., uranium mineralization at Langer Heinrich is associated with the calcretization of valley-fill fluvial sediments in an extensive tertiary palaeodrainage system. Calcrete is a secondary, chemically precipitated limestone that forms under arid to semi-arid climatic conditions. The uranium mineralization occurs as carnotite, an oxidized uranium and vanadium secondary mineral. The deposit occurs over a 15-km length in seven higher grade pods within a lower grade mineralized envelope. The carnotite occurs as thin films lining cavities and fracture planes and as grain coatings and disseminations in the calcretized sediments. Mineralization is near surface, 1 m to 30 m thick and is 50 m to 1,100 m wide.
With the uranium present as a coating on the sediments it unnecessary to grind the material finer, just to remove the surface layer from the individual grains. Consequently, processing employs crushing and scrubbing to break down agglomerates into individual grains and to remove the uranium minerals from the grain surfaces. Cyclones and screens are then used to separate the high-grade fines (leach feed) from barren discard material. Typically the barren solids will contain 40-50% of the solids mass but only 5–10% of the uranium in the ROM feed.
After thickening, the leach feed slurry is conditioned with carbonate and bicarbonate, heated and pumped to the leach circuit. After leaching and heat recuperation, the slurry is fed through a counter current decantation (CCD) circuit in which the high-grade uranium solution is removed from the solids. This solution undergoes further clarification before being pumped through fixed-bed ion exchange columns where the uranium is recovered onto resin. Uranium is stripped from the resin and precipitated as sodium diuranate (SDU) then re-dissolved using sulphuric acid before being re-precipitated with hydrogen peroxide. This product is dewatered, dried and drummed as UO4.
The project is currently in the final stages of an expansion program designed to increase production to 3.7 million lb/y. Equipment design and sizing during this expansion has been carried out with an eye on a further expansion to 6 million lb/y in 2010. A feasibility study for this was recently completed and detailed engineering was scheduled to commence in the March quarter 2009, according to Paladin Energy.
Los Pelambres to Install CiDRA’s Sonar-Based Flowmeter Technology in Concentrator
CiDRA Minerals Processing recently announced that it has been awarded, through Bechtel Chile Ltda, a third expansion contract to supply SONARtrac process monitoring systems to Minera Los Pelambres in Chile, the world’s fifth largest copper mine. The SONARtrac systems will provide volumetric flow measurements on critical slurry lines within the concentrator plant, and work integrally within the Los Pelambres expansion project awarded to Bechtel. This contract is part of the Repower 2 Project at Minera Los Pelambres scheduled for completion in 2010, and which will increase the capacity of the mine's concentrator from 132,000 mt/d to 159,000 mt/d.
The project, located in the Andes about 200 km from Santiago, comprises two main work sites: the mine area and primary crusher at an elevation of almost 3,000 m, and the concentrator at 1,600 m. A conveyor transports ore from the crusher to the concentrator.
CiDRA describes SONARtrac flow technology as “a new class” of industrial flowmeter, utilizing measurement principles that are distinct from all other flowmeter technologies operating in the mining industry. SONARtrac non-intrusive flow monitoring systems make no contact with the slurry and can be removed and reinstalled when it is necessary to replace the pipe. According to Wallingford, Connecticut, USA-based CiDRA, its SONARtrac systems demonstrate a very stable output in the presence of a variety of ores. The passive, sonar-based technology is claimed to enable measurement of single phase and multiphase fluids, as well as slurries, with the same level of accuracy and performance.