| Jinchuan Group Ltd (referred to as the Jinchuan company) is a large non-ferrous metallurgical and chemical joint enterprise including mining, dressing, smelting and chemical engineering. Of which, the production of nickel and platinum group metals accounts for more than 90% of China. Known as the "China nickel", Jinchuan is the largest nickel and cobalt production base. Jinchuan nickel mine is a super large copper-nickel sulfide deposit that is rich in MgO gangue minerals, if a lot of serpentine mix into concentrate, it will bring problems to smelting.For nickel sulfide ore, people mainly adopt flotation process at home and abroad. There are mines by means of biological metallurgy to extract, but very small in size, industrialization is not realized. This study intends to start from the low grade nickel concentrate, adopt the method of magnetic coating to make fine ferroferric oxide in the selective adsorption on nickel pyrite surface, and then be separated by magnetic separation method.The paper took low grade nickel concentrate in Jinchuan as the research object, by means of spectral semi-quantitative, chemical element analysis, XRD analysis and mechanical analysis of detection to stuy the properties of ore. And results showed that low grade nickel concentrate was mainly composed of pentlandite, non metallic mineral was mainly serpentine. Of which, nickel grade was 3.25%, and the content of MgO was 8.58%. In addition, the content of Ni increased gradually along with the thinner of particle size, and the distribution of MgO in each fraction was uniform.In the process of magnetic coating, magnetite played an important role. Fine magnetite selectively lid on purpose particles and improved its magnetism, then magnetic separation could be used to separate. PH could control the mineral surface potential, creating conditions for magnetic coating. Sodium hexametaphosphate could be spread to serpentine, preventing its adhesion to the pentlandite surface. Oleic acid and kerosene in the pulp suspension could produce strong hydrophobic effect with the hydrophobic particles, making the non-polar oil droplets spread on the surface of hydrophobic particles and forming oil film covering, thus further enhanced the hydrophobicity of particle.Results of magnetic coating on pure pentlandite showed, in the magnetic field strength of 200kA/m, the recovery of pentlandite before and after treatment by magnetite was 75.79% and 97.9% respectively, increasing 22.11 percentage points. While the serpentine recovery before and after treatment was respectively 2.04%and 3.18%, little change. Selective magnetic coating of magnetite on pentlandite was achieved.For magnetic coating on artificial mixed minerals, after magnetic separation in the condition of 80kA/m, the grade and recovery of nickel was respectively 22.07% and 82.20% under the optimal reagent conditions, while the grade and recovery of nickel concentrate directly by magnetic separation without any treatment was 27.27% and 46.53%. So the recovery increased 35.67 percentage points. The grade and recovery of MgO after treatment was 2.53% and 3.54% separately, compared with 1.97% and 2.03% before treatment, the change was small. It followed that selective magnetic coating of magnetite on pentlandite was also achieved.We conducted magnetic coating test on low grade nickel concentrate, then carried out magnetic separation under the condition of 95kA/m. Recovery of Ni in magnetic concentrate before and after treatment was 76.38% and 92.83%, increasing about 16 percentage points. While the grade and recovery of MgO after treatment was 6.67% and 73.75% respectively, and they were 7.73% and 62.82% before treatment. The content of MgO reduced 1.06 percentage points. Results showed that magnetic coating-magnetic separation can reduce the content of MgO of Jinchuan low grade nickel concentrate to a certain extent. But further improvment of the concentrate grade and decline of the content of MgO need to be in-depth researched.Thesis research results provide new ideas for appling magnetic coating on reducing magnesium of nickel ores and the separation of nonferrous metal minerals. |
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