Study On The Mechanism Of Flotation Separation Of Chalcopyrite And Nickel Pyrite By Combined Inhibitor

Copper and nickel are important industrial raw materials, which are widely used in electrical appliances, light industry, transportation, construction industry, machinery manufacturing, defense industry, etc. In recent years, with the rapid development of national economy, requirement of copper, nickel and other metal resources increase, but there is serious imbalance between supply and demand in our country, such as high dependence on foreign and single import channel, etc. It is of great strategic significance and economic significance for maintaining a reasonable and rapid development of the copper and nickel industry to improve the self-sufficiency rate of China’s copper and nickel resources. Domestic traditional copper-nickel separation method adopts lime method, namely under the condition of high alkali (pH≥12), increase floatability difference of copper and nickel to realize separation of copper and nickel. However, extensive use of lime could easily cause many problems such as foam viscosity, mechanical inclusions, etc., which make flotation operation difficulties. At the same time, it is also easy to cause blocking pipe because of scaling and consolidation.The paper studied that under isopropyl ethylthionocarbamate system, whether it was feasibility to reduce dosage of lime by using combined inhibitor; and combined with pure minerals tests, adsorption measurements, potentiometric determination, flotation solution chemistry calculation and pulp potential measurement presented to make mechanism analysis; and using actual ore conducted validated test.Pure minerals flotation tests showed that:the floatability of pentlandite in alkaline medium was inhibited; after comprehensive consideration, determined pH value of the pulp of 9, and under the conditions, the optimum reagent dosage of isopropyl ethylthionocarbamate was 10×10-5 mol/L. Sodium sulfite, lime and lime +sodium sulfite combination had almost no effect on chalcopyrite flotation, and inhibitory effect for pentlandite was gradually increasing. When lime+sodium sulfite combination were adopted, it can realize effectively inhibited for pentlandite at low alkali.Adsorption measurement, potential measurement, flotation solution chemistry calculations and infrared spectroscopy of inhibitors showed that:under low alkali environment (pH 9), the main group Ca2+ of lime first adsorbed on the surface of pentlandite; At the same time, there were reaction between SO32- (main group of sodium sulfite in solution) and Ca2+(adsorption in pentlandite surface), and hydrophilic substance CaSO3 was produced; While preventing isopropyl ethylthionocarbamate adsorption on the surface of pentlandite, sodium sulfite added strengthened the inhibitory effect of lime, thereby decreasing the dosage of lime. At the same time, due to Ca2+ and SO32- rarely adsorption on the chalcopyrite surface and isopropyl ethylthionocarbamate adsorption on the chalcopyrite surface based on chemical adsorption, so the combined inhibitor had smaller effect on floatability of chalcopyrite. Therefore, it is theoretically feasible to realize the separation of copper and nickel in the low alkali environment.Pulp potential measurement and Eh-pH map results showed:Surface thermodynamic calculation showed that:by the combined use of sodium sulfite and lime, can reduce oxidation-reduction potential of pulp, accelerate oxidation rate of pentlandite surface, and promote forming Fe(OH)3, Ni(OH)2, FeCO3 and other hydrophilic compound on the pentlandite surface; at the same time, hydrophobic substance copper sulfide and sulfur (S0) were generated on the chalcopyrite surface, and combined inhibitor added strengthened floatability difference of chalcopyrite and pentlandite.Verification tests of actual ore:the sample, bulk concentrate coming from a mine in Yunnan, was obtained by bulk flotation. In the experiment, firstly concentration and reagent removal for copper-nichel bulk concentrate was conducted, then on the conditions of that grinding fineness -0.043mm 70%, lime 3000g/t, sodium sulfite 2500g/t and isopropyl ethylthionocarbamate 60g/t, adopting "one-time roughing, three-time cleaning and two-time scavenging", effective separation of copper and nickel was achieved; and two products can be obtained:copper concentrate with a grade of 26.14% at the recovery of 80.65%, containing 0.87% Ni; nickel concentrate with a grade of 3.53% at the recovery of 96.91%, assaying Cu 0.81%.