Gravity separation of a UG-2 ore secondary sample for the reduction of chromite minerals

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• 作者：L. Maharaj ; ^{maharajl3@ukzn.ac.za} ; B.K. Loveday ; J. Pocock
• 关键词：Spiral concentrators ; Grinding ; Platinum flotation ; UG-2 ore ; Chromite rejection
• 刊名：Minerals Engineering
• 出版年：2012
• 期刊代码：130_08926875
• 类别：et
• 出版时间：April, 2012
• 卷：30
• 期：Complete
• 页码：99-101
• 文件大小：180 K

摘要

The efficiency of secondary grinding of UG-2 (Upper Group 2) platinum ores is currently limited by the use of open-circuit grinding in many plants, which is inherently inefficient, due to short-circuiting of coarse particles and possible separation by gravity in the mill. The chromium oxide (Crb>2b>Ob>3b>) grade in UG-2 flotation concentrates is generally above 3%and this contributes to low efficiencies during PGM smelting.

Gravity separation of the chromite and silicate particles prior to secondary grinding was investigated with a spiral concentrator. Laboratory cleaner spiral tests were conducted on a plant sample from a secondary ball mill feed, to determine whether a chromite-rich stream could be removed and discarded from the process prior to milling. Analysis of the chromite-rich stream showed that it could not be discarded, as a significant proportion of the Platinum Group Elements (PGEs) in the feed to secondary milling (鈭?6%) would be discarded with about 55%of the chromite minerals. Pilot plant cleaner spiral test work confirmed the trends observed.

An alternative strategy of separate coarse grinding of the gravity concentrate, followed by combined flotation, resulted in a 32%reduction in the Crb>2b>Ob>3b> entrainment to secondary rougher flotation concentrate, and most significantly, an increase of 3.7%in secondary recovery of PGE鈥檚 with the same overall grinding energy as the standard process.