| 摘要 |
The present invention relates to a gravity/flotation circuit where a mineral stream, such as a flotation rougher or cleaner concentrate, undergoes a two stage size separation wherein: i) the screen of the first stage provides a coarse stream of particles greater than 110 microns and a fines stream of particles less than 110 microns; and ii) the fines stream of less than 110 microns is subjected to the second stage separation whereupon a cyclone provides an ultrafine/slimes stream of p80 less than about 25 microns and a middlings stream of p80 greater than around 25 microns. The middlings stream is subjected to flotation to recover nickel sulphide which is sent to final concentrate, and reject or depress magnesia which undergoes gravity separation to concentrate the MgO. It has been discovered that a large proportion of the MgO minerals in the concentrate are contained in the 30 to 100 micron size fraction and that they are well liberated making physical separation possible. Furthermore, the nickel sulphide minerals and magnesia minerals have a significantly different specific gravity which can be exploited using gravity separation equipment to achieve magnesia rejection.
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