Modeling of copper slag leaching and assessment of potential environmental risks

Introduction. In the mining industry, waste is generated at all stages of the production line, including technogenic mineral formations, among which copper smelting slag can pose a potential environmental threat. As a result of the intense anthropogenic load from mining enterprises, acidic precipitation can form, accelerating the leaching of the slag mass stored near the enterprises. As a result, heavy metals can enter the depositing environments. The aim of the research: identification of potential environmental risks of copper slag storage by means of long-term exposure to simulated acidic precipitation on the solid mass of slag. Materials and methods. In the selected slag samples, the elemental composition was determined by X-ray structural and phase analysis, the mineralogical composition was determined by powder X-ray diffraction, the chemical composition in eluates was determined by the method of the inversion voltammetry. Research results. Samples of copper slag stored on the northern outskirts of the city of Karabash, Chelyabinsk region, were taken. In laboratory conditions, tests were carried out by extracting the slag mass with simulated acid precipitation. After 14 days, the eluate was separated from the solid phase, in which the content of Zn, Cd, Pb, Cu, Fe was determined, then the solid phase of the slag was filled with a new portion of extractants. The results of mineralogical and chemical analysis of the slag indicate the presence of sulfide minerals in its structure and containing the studied heavy metals. Discussion of the research results. During the tests, significant concentrations of metals were recorded in each portion of the eluate throughout the entire experiment. Heterogeneity was observed in the rate of metal transfer to the solution, with a cyclical increase and decrease in concentrations on average after 60 days. At the end of the experiment, the total yield for the studied metals was ranked in the order of Zn>Cu>Pb>Cd. Conclusion. Based on the results of the work, it can be concluded that the storage of copper slag from pyrometallurgical smelting under conditions of increased anthropogenic load and exposure to acidic precipitation poses significant environmental risks to the associated depositing media. Resume. The specific mineralogical and chemical composition of copper slag, as well as the migration capacity and behavior of leaching products, allows us to draw a number of conclusions regarding the presence of environmental risks for the environment when storing slag under conditions of intensive technogenesis. When exposed to acidic precipitation, heavy metals are leached from the slag. The results of the conducted research can contribute to the revision of the technology of storage and use of copper slags pyrometallurgical smelting in order to minimize the environmental risks, as well as to find new ways of their use.

Copper · Copper slag · Precipitation · Smelting · Sulfide · Industrial Engineering and Technologies · Metal Extraction and Bioleaching · Tailings Management and Properties