Heavy metal-rich acidic soils of copper sulfide mines can easily cause harm to the surrounding environment and ecosystem safety if not treated properly. Currently, the most common method of mine ecological remediation is to improve acidic soils of copper sulfide mines by adding different types of amendments. In this paper, different dosages of biochar and carbide slag applied singly and in combination were designed to investigate the changes of physicochemical properties and ryegrass growth in the acidic soil of copper sulfide mines. Through soil incubation experiments and potting tests, different treatments explored the improvement effect of carbide slag combined with biochar on the acidic soil of copper sulfide mines. Then, it was found that 2% (w/w) carbide slag in combination with 10% (w/w) biochar had the best effect on the improvement of copper-sulfide mine acidic soil. Among them, carbide slag significantly increased the pH, cation exchange capacity (CEC) and acid neutralization capacity (ANC), and reduced the electrical conductivity (EC), net acid generation (NAG) and sulfate ion (SO42−) concentrations in the acidic soil of copper sulfide mines; biochar obviously reduced the bio-effectiveness of heavy metals Cu, Pb and Zn, and DPTA-Cu, Pb and Zn decreased by 8~80%, 7~76% and 17~79%, respectively. Apart from that, there was a positive cooperativity between carbide slag and biochar, and their application effectively controlled the acidification process and heavy metal toxicity in the acidic soil of copper sulfide mines. In summary, the results will provide a theoretical basis for the large-scale reclamation of carbide slag and biochar in improving acidic soils of copper sulfide mines, filling the gap of calcium carbide slag and biochar in soil remediation.

Heavy metal-rich acidic soils of copper sulfide mines can easily cause harm to the surrounding environment and ecosystem safety if not treated properly. Currently, the most common method of mine ecological remediation is to improve acidic soils of copper sulfide mines by adding different types of amendments. In this paper, different dosages of biochar and carbide slag applied singly and in combination were designed to investigate the changes of physicochemical properties and ryegrass growth in acidic soil of copper sulfide mines. Through soil incubation experiments and potting tests, different treatments explored the improvement effect of carbide slag combined with biochar on acidic soil of copper sulfide mines. Then, it was found that 2% (w/w) carbide slag in combination with 10% (w/w) biochar had the best effect on the improvement of copper sulfide mine acidic soil. Among them, carbide slag significantly increased the pH, cation exchange capacity (CEC) and acid neutralization capacity (ANC), and reduced the electrical conductivity (EC), net acid generation (NAG) and sulfate ion (SO42−) concentrations in the acidic soil of copper sulfide mines; biochar obviously reduced the bio-effectiveness of heavy metals Cu, Pb and Zn. Apart from that, there was a positive cooperativity between carbide slag and biochar, and their application effectively controlled the acidification process and heavy metal toxicity in the acidic soil of copper sulfide mines. In summary, the results will provide a theoretical basis for the large-scale reclamation of carbide slag and biochar in improving acidic soils of copper sulfide mines.

Purpose HDS sediment is a type of solid waste produced when the high-concentration mud method (HDS) is adopted to treat acid wastewater from copper mines. It can rationally utilize sediment resources by using phytoremediation. Methods To reveal the effect of different phytoremediation on the heavy metal, enrichment capacity and microbial diversity of the HDS sediments of copper mines, in this experiment, the HDS sediments of a copper mine without phytoremediation were selected as the control group, while the sediments of black locust (Robinia pseudoacacia), slash pine (Pinus elliottii Engelmann) and Chinese white poplar (Populus tomentosa Carr.) were used as test groups to analyze the physical and chemical properties, heavy metal pollution and bioaccumulation capacity of HDS sediments under three phytoremediation. Results The results show that different phytoremediation can reduce the sediment's conductivity and adjust the sediment's pH value to the range suitable for plant growth. The BCFShoot and BTF values of Chinese white poplar to Cd and Zn and slash pine to Pb were both greater than 1. Conclusions As discovered from the bioconcentration coefficient and biotransport coefficient results, Chinese white poplar is an enriched plant of Cd and Zn, while slash pine is a plant full of Pb.

The copper sulphide mining process would produce a large number of copper tailings that can be treated with different substrates so as to act as guest soil in the ecological reclamation of the mine. Tall fescue (Festuca arundinacea Schreb) is a fast-growing herbal medicinal plant with a large biomass and significant adaptability that is often used as pioneer plant in early mining soil reclamation. In order to reveal the influence of different copper tailing treatment substrates on plant growth, in this experiment, tall fescue (Festuca arundinacea Schreb) was planted under potted conditions for the purpose of exploring the effect of different exogenous substrates such as conditioning agents, sulfurized modified straw, effective microorganisms (EM), and High-density Sludge (HDS) sediment on tall fescue height, biomass, chlorophyll, catalase (CAT) activity and Cu2+ transport under copper tailings substrate. Then, the results showed that the combined application of different exogenous substrates (conditioning agents, EM, sulfurized modified straw and HDS sediment) reduced the pH of the copper tailing substrate to varying degrees, with a decrease of 5%-21%. Besides, compared with the control group and other treatments, the combined treatment of conditioning agents, sulfurized modified straw, and EM has a significant impact on the biomass, plant height, chlorophyll content, CAT activity and other physiological indicators of tall fescue and can effectively reduce Cu2+ that is toxic to tall fescue in copper tail sand.