Research On Inhibitors Of Mg-containing Gangue Minerals In Copper-nickel Sulfide Ore Floatation

Nickel resources that have been exploited in our country are almost low gradecopper-nickel sulfide ores with Mg-containing silicate gangue minerals. Therepresentative of which is JinChuan company—the largest production base of nickelin China. Production practice shows that, the Mg-containing gangue minerals incopper-nickel sulfide floatation concentrate not only seriously affect the concentratequality, but also bring a lot of trouble on the subsequent smelting, therefore, thereaserch of floatation magnesium decreasing on copper-nickel sulfide ores withMg-containing silicate gangue minerals is significant.The nickel ores used in this paper were from the No.2mining area in JinChuan.On the base of analysising and summarizing a large number of domestic andinternational related literatures, and fully analyzed the properties of the raw ore, thearticle put forward the new idea for floatation magnesium decrease by applying thecombination of complexing agent-inhibitors. The single factor test, open circuit andclosed circuit test of disodium EDTA-sodium hexametaphosphate reagent system,oxalic acid-sodium hexametaphosphate reagent system and ammonium sulfate-coppersulfate-sodium hexametaphosphate reagent system (JinChuan plant reagent system)were carried out. In this paper, the research about the mechanism of flotation reagentshave also been made.The results of multi-element and phase analysis showed that: the raw orescontained1.29%nickel,0.87%copper,29.02%MgO, the main form of nickel andcopper was sulfide. X-ray diffraction analysis results showed that: in raw ores, themain useful minerals were pentlandite and chalcopyrite, the main gangue mineralswere serpentine, talc and chlorite.The optimal conditions of disodium EDTA-sodium hexametaphosphate reagentsystem were: grinding fineness-0.074mm accounted for88.68%, disodium EDTAdosage2500g/t, sodium hexametaphosphate dosage200g/t, slurry pH value9.5, butylxanthate dosage200g/t, J622dosage40g/t, JC (Homemade inhibitor) dosage3000g/t.For the raw ores, from the closed-circuit process of one roughing-two cleaning-threescavengings-middlings returning in proper order into the flow, the final copper-nickelmixed concentrate obtianed from the disodium EDTA-sodium hexametaphosphate reagent system had Ni grade of8.95%, nickel recovery of82.91%, Cu grade of5.21%,copper reovery of71.64%，MgO content of6.13%.The optimal conditions of oxalic acid-sodium hexametaphosphate reagentsystem were: grinding fineness-0.074mm accounted for88.68%, oxalic acid dosage1500g/t, sodium hexametaphosphate dosage200g/t, slurry pH value9.5, butylxanthate dosage200g/t, J622dosage40g/t, JC dosage3000g/t. For the raw ores, fromthe closed-circuit process of one roughing-two cleaning-three scavengings-middlingsreturning in proper order into the flow, the final copper-nickel mixed concentrateobtianed from the oxalic acid-sodium hexametaphosphate reagent system had Nigrade of8.71%, nickel recovery of82.38%, Cu grade of5.11%, copper reovery of71.78%，MgO content of6.31%.On the basis of the optimization in the laboratory experiment, the finalcopper-nickel mixed concentrate obtianed from the Jinchuan plant reagent system hadNi grade of8.73%, nickel recovery of81.59%, Cu grade of5.13%, copper reovery of69.73%，MgO content of6.75%. Compared with the JinChuan plant reagent system,disodium EDTA-sodium hexametaphosphate and oxalic acid-sodiumhexametaphosphate reagent system could control the MgO-content in concentrate lessthan6.5%while guaranteeing the grade and recovery of Ni, Cu.The results of Zeta potential measurment showed that: the zero point ofpentlandite used in tests was pH=3.0, and the zero point of serpentine was pH=9.8.Both the zero point of pentlandite and serpentine could be greatly reduced by sodiumhexametaphosphate and JC.The results of Infrared Spectroscopy and collector adsorption measurment ofpentlandite and serpentine pure mineral showed that: butyl potassium xanthatecouldn’t adsorption at the surface of clean serpentine, but could adsorption at thesurface of serpentine which activated by CuSO4; disodium EDTA and oxalic acidcould effectively eliminate the activation of CuSO4on the serpentine, but didn’t affectthe adsorption of butyl potassium xanthate at the surface of pentlandite.Analysising the results of solution chemical calculation and each systemLgC-pH diagram the conclusion could be found that disodium EDTA and oxalic acidhad strong complexation and stabilization with Cu2+and Ni2+, the Cu(OH)2(s),Cu(OH)2aq, Cu(OH)+, Ni(OH)2(s), Ni(OH)+and Ni(OH)2aqin solution could be complexed and stabilized by disodium EDTA and oxalic acid, thereby removing thefloatation activation center at the surface of Mg-containing gangue minerals such asserpentine, chlorite and talc.