Engineering and Mining Journal - Whether the market is copper, gold, nickel, iron ore, lead/zinc, PGM, diamonds or other commodities, E&MJ takes the lead in projecting trends, following development and reporting on the most efficient operating pr
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its customers," said Philip Lake, the compa- ny's international business unit leader. "WesTech is now poised to provide spare parts and service to existing tower press filter operators around the world, at a service level and price that will be extremely competitive." The tower press filter has a five-stage operating cycle, encompassing feed, filtra- tion, washing, air-drying and cake-dis- charge stages. Metso Thickeners Cut LKAB's Pump Costs While the use of thickener technology is often associated with the back end of min- eral processing plants, there are other applications, as Metso Minerals points out. A recent paper by product manager Pejman Oghazi and some colleagues looks at the ways in which mine water can be treated underground, the aim being to save wear-and-tear on pumping systems by han- dling raw water that would need to be treat- ed on surface in any case. The authors explained that Metso has a system solution to treat mine water, by sepa- rating out the solids before it is pumped to surface. This system, they said, reduces pump erosion and can save on maintenance in the long term. It can be divided into three steps: a spiral dewaterer to remove coarse solid particles; a lamella thickener to remove most of the solids; then a tube press to han- dle the sludge from the thickener underflow. The concept is based on a project that the company undertook for the Swedish iron-ore producer, LKAB, involving the installation of equipment at a dewatering station, 1,368 m below surface. The spiral dewaterer is basically an open trough with arrangements to transport settled solids in a continuous operation, and replaces a tra- ditional settling process in an open pond or sump. Metso produces these units in sizes to cover a hydraulic flow of up to 2,000 m 3 /h. The settling area is dimen- sioned to allow solids to settle in relation to the feed flow and solids cut-point. Metso's inclined plate settler consists of two main components: an upper tank con- taining the lamella plates inclined at 55° and a lower conical or cylindrical sludge tank. The feed enters through vertical cham- bers on either side of the lamella packs, with clarification taking place above the suspen- sion inlet so there is no mixing of the clari- fied fluid with the incoming feed. The solids hit the lamella plates and slide down to the sludge tank where they are thickened further and compressed using a raking system. Coal-industry Standard Filters With its headquarters near Salt Lake City, Utah, Peterson Filter Corp. reported that the first of its "Coal Type" vacuum disc fil- ters were installed in the eastern U.S. in the late 1950s; since then, these units have become an industry standard in the coal preparation industry, with more than 400 in service. They are used in fine-coal preparation circuits for filtering clean coal and refuse slurries, the company stated. Peterson noted that since flocculation of the fine coal filter feed slurry is often needed in order to obtain acceptable filtra- tion rates, together with low cake moisture, it has developed a highly efficient floccula- tor that can be used to condition both thickener and filter feed slurries. It added that as refuse slurries often have a high ash content and hence lower filter rates and higher cake moisture, proper flocculent feed slurry conditioning is essential for acceptable filter operation. The company offers a complete line of disc filters, ranging from 18-in.-diameter laboratory-size units to full-size 12 ft. 6-in.- diameter production units with 15 discs. In addition to its coal-type filters, it has a sim- ilar line of equipment for filtering concen- trates and tailings slurries in metallurgical mining, as well as drum-type filters that can be customized for specific mining-sec- tor applications. Bilfinger Boasts Largest Filter Press Bilfinger Water Technologies (formerly known as Diemme) has designed and sup- plied complete filtration plants for the min- erals sector. Process areas covered in these projects have included the use of filter presses for concentrate dewatering, filter- ing lixivants in hydrometallurgical plants, dewatering slurries from off-gas treatment in pyrometallurgy, and the recovery of met- als through electrolysis. Among the Bilfinger filter presses for the minerals sector, the GHT 4 x 4 is designed for high productivity. The filter plates are hung from an upper beam and are moved automatically, with the shifting mechanism equipped with a carousel sys- tem that reduces the filter press opening and closing sequence to the minimum. Effectively guarded moving parts and the use of state-of-the-art electronic interlock systems mean that the press conforms to the highest operator health and safety reg- ulations, the company said. In addition, routine maintenance is simple, with easy access to the filter plates for both inspec- tion and filter-cloth replacement. In 2010, Bilfinger supplied what it claims is the world's largest filter press, the GHT 2500, to a steelworks in India, for dewatering iron-ore concentrate. The unit also uses up-to-date technology to reduce the filtration cycle of cake blowing, drying and squeezing to a minimum. Capable of being expanded, it can handle up to 200 mt/h of product to a residual cake moisture content of between 5% and 9%, according to Bilfinger. The year before, the company had sup- plied a silver producer in Mexico with three GHT 2000 filter presses that could dewa- 50 E&MJ; • MARCH 2014 www.e-mj.com F I LT E R S A N D T H I C K E N E R S An Andritz fast-opening mining filter press for iron-ore concentrate in India. EMJ_pg46-58_EMJ_pg46-58 2/28/14 3:11 PM Page 50