Behaviors And Mechanisms Of Silicate Minerals Containing Magnesium In The Flotation Process Of Cu-Ni Sulphide Deposit

Nickel resources that have been exploited and utilized are almost nickel sulfide deposits in our country. Nickel reserves is relative centralization, in which Jinchuan nickel deposit is the biggest in our country and also is one of three oversize deposits of nickel sulfide in the world at present. The flotation is the common method to be used for separating Cu-Ni sulphide deposit. However, there always exists a difficult problem for many years, which is to decrease the content of MgO in concentrate. It is adverse to realize comprehensive development and utilization of nickel resources that the content of MgO in concentrate dropped less than 6.5 percent to result in the decrease of Ni recovery because the nickel sulfide deposit in Jinchuan is a kind of serious serpentinization ore and the main nickel mineral in it is pentlandite.On the basis of the summary and analysis of many related references at home and abroad, in this paper objects of study were serpentite and amphibole which both are the main gangue minerals of silicate with high grade of MgO in Cu-Ni sulphide deposit, and under the premise of full knowledge on mineral ingredients of serpentine and amphibole, adopted monothetic experimental method to systematically study the behaviors in the flotation process of Cu-Ni sulphide deposit. Meanwhile, through the analysis of crystal structures of these two minerals and using various measuring and testing techniques such as Zeta potential measurement, infrared spectroscopy, contact angle measurement and extent of adsorption, the flotation mechanisms of serpentite and amphibole in the separating process of Cu-Ni sulphide deposit had been investigated.The experimental results of single mineral flotation indicated that both serpentite and amphibole showed some natural floatability, but the natural flotability of amphibole was better than serpentine's; Serpentine didn't react with the two type of xanthate and dithiophosphate basically, and amphibole has a weaker adsorption with them; The flotation effects with mixed reagents to the two minerals were not very different from ones with reagents alone; The activation of copper ion occurring on the surface of serpentine was not obvious, but under the environments of strong acid or alkali copper ion had strong activation on the surface of amphibole, and under the natural pH value of pulp about 9.3, adding copper ion could depress the flotation of amphibole in a certain degree; Sodium hexametaphosphate, carboxymethyl cellulose, J622 and sodium silicate were both depress the flotation of these silicate minerals, and compared with carboxymethyl cellulose and sodium silicate, the inhibitory effects of J622 and hexametaphosphate were better and lower dosage.The analysis of crystal structure showed that serpentite has a layer structure and there are a large number of carboxy-and Si-0 bond on it's surface; Amphibole is a double chains of silicate mineral, a large number of Si-0 bond are exposed on it's surface; Thus, they prone to hydration and be good wettability, particularly serpentite.The testing results of Zeta potential measurement on the surface of these minerals illustrated that corresponding to the "zero point" of serpentine used in the tests, the value of pH was about 9.3; Cu²⁺and various collectors reduced Zeta potential measurement on the surface of serpentine in less different degree, but as to depressors the decreasing change was great; The flotation of copper nickel sulphide deposit is usually under the condition of natural value of pH or alkaline, in which the decreasing order of Zeta potential measurement on the surface of serpentine treated by various depressors was as follows: sodium hexametaphosphate (6P)≥carboxymethyl cellulose (CMC) > sodium silicate≥J622.Corresponding to the "zero point" of amphibole used in the tests, the value of pH was about 4.9; Cu²⁺ and various collectors reduced Zeta potential measurement on the surface of amphibole in less different degree, but as to depressors the decreasing change was great; The flotation of copper nickel sulphide deposit is usually under the condition of natural value of pH or alkaline, in which the decreasing order of Zeta potential measurement on the surface of amphibole treated by various depressors was as follows: sodium hexametaphosphate (6P)≥J622 > carboxymethyl cellulose (CMC) > sodium silicate.The results of adsorption measurements showed that ethyl and butyl xanthates on the surface of serpentite were little and a small number adsorption on the surface of amphibole.The measurement results of contact angle of amphibole showed that amphibole possesses natural wettability; In addition to adding butyl ammonium aerofloats could increase the contact angle of amphibole, others reduced it in varying degrees, but change was not significant.FT-IR results showed that there could not only find many characteristic vibratory absorption peaks of mineral groups but also appeared some reagents', and the absorption peaks of minerals took place in slight displacement. This reflected that chemical adsorption in varying degrees had been occurred on the surfaces of serpentine and amphibole, but chemical reactions occurred on the two mineral surfaces were not totally same.