DE-XRT method to separate platinum ore

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Abstract

The Potgietersus Platinum mine is an open pit mine in the Bushveld Complex in South Africa. During the mining different rock types are mined, some of these are detrimental. The goal of the research done in this project is to assess the feasibility of Dual Energy X-ray Transmission (DE-XRT) to distinguish the detrimental ore types from the rest of the ore. There are two types of rock that contain the most platinum and Platinum Group Elements (PGE's): pyroxenite and pyroxenite B. The detrimental rock types are serpentinite, norite, calc- silicate and oxidized material. Detrimental rock types cause a lower recovery of the processing of the minerals. By removing the detrimental rock types the recovery could increase. DE-XRT is a sensor based sorting method based on density differences of the materials that have to be distinguished from each other. Samples of the different rock types have been scanned with a DE-XRT scanner and the pictures of these samples consist of pixels. Of each pixel the High Energy Absorption (HEA) and Low Energy Absorption (LEA) are known. With this data a color is allocated to each pixel. Ratios of these colors are plotted in graphs. From these graphs it can be concluded that a seperation can be made by using the ratio between the number of green and blue pixels. By using the green/blue ratio more than 60% of the calc silicate, 30% of the norite, 100% of the oxidized material and 60% of the serpentinite are removed. There is no loss of pyroxenite and pyroxenite B. It is recommended to do further research on other software or to improve the now used software. Also large scale experiments have to be conducted to find out if this method can be used in the mine itself. And a feasibility study has to be performed to see if a large enough percentage of the detrimental rock is removed to make the investment profitable.