Abstract:

In order to study the processing mineralogy characteristics of nickel ore in South Central Africa, and provide a basis for its reasonable recovering，use the X ray fluorescence spectrum analysis, multi element analysis, X ray diffraction and microscopic examination and statistics, the chemical and minerals composition and embedding characteristics, ore structure and texture and the granularity of pyrrhotite and nickel pyrite are analyzed.According to the results of XRF analysis:The main chemical compositions of the ore are iron, sulfur, silicon, magnesium, calcium, nickel, copper, aluminium,cobalt and so on,in these elements,the nickel can be used in industrial, and the copper, cobalt, sulfur are valuable elements,which can be recovered comprehensively.The results of multi-element analysis showed that the content of nickel in the ore is 3.42%,the main associated impurities are SiO₂, MgO and CaO.Through X-ray diffraction analysis, microscopic detection and statistics, concluded that the main mineral composition of the ore is pyrrhotite with a content of 76.06%, nickel-bearing pyrite with a content of 9.74%, and gangue minerals with magnesium silicate minerals such as dolomite, talc and chlorite with a content of 7.75%, 2.39% and 1.43%, respectively.The study on the structure and dissemination characteristics of the ore showed that the dissemination size of pyrrhotite in the ore is mainly coarse and uniform, and the dissemination size of nickel pyrite is also coarse, but not uniform. Pyrrhotite,nickel pyrite and chalcopyrite coexist closely,and have interpenetration,encapsulation and substitution phenomena.They are closely distributed in aggregates, forming massive ore structures.In addition, a small number of pyrrhotite, nickel pyrite and magnetite are distributed in gangue minerals in granular form, showing disseminated structure.Some gangue minerals are veined along pyrrhotite and nickel pyrite. Intergranular, fissure filling cementation forms vein-like, reticular structure.The results of particle size measurement and analysis of pyrrhotite and nickel pyrite in ore under microscope show that the pyrrhotite in ore is mainly coarse grained, mainly distributed in the range of +75 micron, the content of +150 micron is 92.76%, the content of fine grains is less, and the distribution is uniform; The size of pyrrhotite is coarse, but the distribution is not uniform,except for the content of +150 micron is 38.2% and the content of pyrrhotite is more than that of +150 micron. Except for 16.63% of -150+100 μm grain size, the content of other grain size ranges is about 10%.On the whole,the ore with high nickel grade,the granularity of nickel bearing minerals is relatively coarse, which is easy selection ore.The existence of magnesium bearing minerals, such as dolomite and talcum,affect the separation of nickel ore.

Key words: nickel ore, process mineralogy, magnesium bearing gangue minerals, structure and texture, disseminated grain size