The effect of ferrous sulfate, sodium sulfide and their mixtures on the flotation of sphalerite in the alkaline medium

Abstract

Introduction. The quality of the enrichment process is affected by many factors, ranging from the characteristics of the raw materials supplied to the enrichment plant to the enrichment technology and the agents used. Strict process control is required at all stages from mining to concentrate extraction. Copper-zinc ores of Russian deposits are difficult for enrichment due to high mass fraction of pyrite in ore and fine irregular intergrowth of sulfide minerals between themselves and with rock minerals. The practice of enrichment of copper-zinc ores has established that it is impossible to obtain high-quality zinc and pyrite concentrates without adding sphalerite flotation modifier agents to various flotation operations. To improve the flotation activity of sphalerite, copper sulphate is used as an activation additive in the enrichment process chain. Purpose of work. To study the effect of sulfhydryl collectors on flotation of sulfide minerals, and development of innovative technologies of flotation of copper-zinc and polymetallic ores considering the acidity of the environment. Materials and methods. In the experimental part of the work, several methods of materials and agents preparing were used, a variety of equipment was used, as well as methods of analysis and processing of results. The material composition and grain size distribution of sphalerite was studied using the MLA System Quanta. X-ray phase analysis of sphalerite was carried out at the University of science and technology "MISIS" in Research Laboratory of ultra-hard materials on Rigaku Geigerflex device using monochromatized CuKα-radiation. Thermographic studies were carried out using a Q -1500D derivatograph. The following flotation agents were used in the work: collector - butyl potassium xanthate, foam agent MIBC, medium regulator - lime, modifiers - iron sulfate, sodium sulphide and mixture of iron sulfate and sodium sulphide. Flotation experiments were carried out on the laboratory flotation machine FL-189 G. Results. The kinetics of sphalerite flotation is characterized not by a single value of the flotation kinetics constant for all flotation mineral grains, but by a set of such values corresponding to quite certain fractions of sphalerite extracted in the foams product. It has been found that in the initial period of flotation the mineral grains with a high value of the flotation velocity constant are flotated, and in the final period of flotation the grains of the same mineral with a low value of the same flotation velocity constant are flotated. Discussion. The introduction of iron (II) sulphate into the mineral slurry leads to a redistribution of the flocculated mineral between medium and lightly flocculated fractions. This indicates that iron (II) sulphate acts as an activator for sphalerite flotation. At a low flow rate of this agent, the proportion of medium flotable fractions increases and the proportion of easily and hardly flotable fractions decreases. With increase in the agent consumption up to 400 g/t and more, the opposite picture is observed - the proportion of medium flotable fraction decreases and the proportion of easily flotable fraction increases in flocculated sphalerite. The replacement of iron (II) sulphate by sodium sulphate has the opposite effect on the flotation spectrum of sphalerite. The introduction of a mineral suspension of a solution of sodium sulfide and iron (II) sulfate into the liquid phase at a consumption of 200 g/t of each agent leads to a decrease in the proportion of easily and especially medium floatable fractions of the mineral and an increase in the proportion of difficultly floatable fractions. Conclusions: 1. An increase in the pH of pulp liquid phase leads to a decrease in the extraction of zinc concentrate in the foam product during flotation with butyl xanthate. 2. The introduction of a solution of sodium sulfide with ferrous sulfate reduces the floatability of the mineral, which is reflected in a decrease in the extraction of zinc concentrate. 3. Sodium sulfide and iron sulphate, while simultaneously dosing them into the flotation pulp, act as depressants in the sphalerite flotation process. 4. Sodium sulfide depresses sphalerite at all studied pH concentrations. Resume. The results of the research can be useful in improving the methods for processing sulfide ores (lead-zinc and copper-zinc) which are included in the group of polymetallic ores. The developed methods of flotation processing make it possible to improve the quality of enrichment and increase the extraction of a valuable component.