The Asia Miner

JAN-FEB 2017

The ASIA Miner - Reporting Important Issues to Mining Companies in the Asia Pacific Region

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VDMA 69 2017 • VDMA MINING SUPPLEMENT Water and energy savings have become more and more important for miners worldwide. "We introduced HPGR to the mining industry," said Uwe Schuh, head of department grinding technology mineral processing, thyssenkrupp. "We still consider ourselves to be the market leaders. Borrowing a concept from the cement industry, thyssenkrupp is proposing dry grinding up to approximately 150 microns. "This con- cept would eliminate the conventional milling stages and report di- rectly to the downstream beneficiation processes," Schuh said. "The concept consist of a combination of HPGR and air classifiers, and it would be of particular interest to iron ore processing plants." Eliminating part of the wet circuits (grinding) would significantly reduce water consumption. "For the fine grinding (down to 20 microns) of disseminated ore to liberate metals, tower mills could be an option, according to Schuh. Recently, thyssenkrupp signed a cooperative agreement with Eirich, the company that invented the tower mill. "Eirich's upper limit for tower mills was 1,500 hp and under the agreement, we will develop a 6,000-hp tower mill," Schuh said. "In the future, we see the combination of the HPGR with a tower mill positioned downstream." Selecting the Proper Pump to Handle Concentrate Many gold operations process ore through autogenous grinding mills. Ground ore is classified for size through hydrocyclone separators. Ball mills regrind the coarse material. The undersize reports to flota- tion where the sulfide minerals are separated, concentrated and sent to a thickener-filter press circuit prior to roasting. The thickener-filter press circuit reduces the amount of water in the flotation concentrate, which is typically handled using horizontal centrifugal pumps. The use of this type of pump can be counter-pro- ductive because water must be added on the thickener cone bottom to assist transport by the pump. Also, gland seal water must be added to the centrifugal pumps in the two pumping stages. In total, the volume of water introduced back into the thickened underflow fed to the filter press can be increased by as much as 25%. Mineral Processing: Recovering More with Less Minimizing the Use of Water and Energy After introducing high-pressure grinding (HPGR) technology to the mining industry, thyssenkrupp plans to integrate its use with tower mills to reduce water consumption at mineral processing plants.

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