Phytoremediation is considered to be the most environmentally friendly green restoration technology for dealing with mine waste. Adding amendments can improve the substrate environment for plant growth and enhance remediation e ciency. Herbaceous plants have become the preferred species for vegetation restoration in abandoned mines because of their fast greening and simple management. Considering that, in this paper, to explore the effect of composite amendments on physicochemical properties of copper tailings repaired by herbaceous plants, the untreated copper tailings were employed as the control group, whereas copper tailings repaired by ryegrass (Lolium perenne L.), vetiver grass (Vetiveria zizanioides L.) and tall fescue (Festuca arundinacea Schreb) with or without conditioners and straw combination into the compound amendments, were taken separately as the test group. After 6 months of planting, the pH, electrical conductivity, water content, available potassium, organic matter, total nitrogen and available phosphorus in the main physical and chemical properties of copper tailings in each experimental area were analyzed. The results showed that the electrical conductivity, organic matter and total nitrogen content of copper tailings were improved to a certain extent by planting herbs without treatment. Meanwhile, compared with the control group, all indexes of planting herbs showed an upward trend after adding composite amendments. Among them, pH, water content and available potassium content of copper tailings were enhanced more obviously. Furthermore, as discovered from the grey correlation analysis results, vetiver grass planted with composite amendments has the best comprehensive effect of improving the physicochemical properties of copper tailings, followed by tall fescue and ryegrass.

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. In order to reveal the influence of different copper tailing treatment substrates on plant growth, in this experiment, tall fescue (Festuca arundinacea) 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%. Moreover, 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 tailing.

After the closure of the large tailing pond of copper sulfide mine, ecological restoration must be carried out. The ecological restoration method of directly using tailing as a vegetation matrix to replace guest soil is a new method. The key to this method lies in improving the substrate environment and carry out phytoremediation. A field test was performed to carry out an enhanced phytoremediation technique for multi-metal contaminated copper tailings by Sudan grass (Sorghum sudanense (Piper) Stapf.), ryegrass (Lolium perenne L.), and Bermuda grass (Cynodon dactylon), using conditioner (TH-LZ01) and straw combination into composite amendments as soil amendments, aimed to obtain the maximum of phytoremediation effect. The 5% conditioner and 0.5% straw (C2S2) were recommended as the optimum chemical proportions for amendment materials. We could find that the chlorophyll, catalase activity, plant length and fresh weight in the 5% conditioner and 0.5% straw (C2S2) applied treatments were notably higher when compared with those of other treatments, indicating that composite amendments could alleviate the toxicity of metals to plants. In addition, adding composite amendments can obviously improve the restoration effect of Sudan grass, ryegrass and Bermuda grass on the pH, water content, electrical conductivity and organic matter of copper tailings. Compared with no treatment, the absorption of metal in leaves of plants treated with composite amendments is lower, but that in roots is enhanced, revealing that the stability of metal in roots is enhanced by composite amendments treatment to a great extent. By applying composite amendments, the metal removal effect of ryegrass appeared to be particularly effective, and by the following order: Cd (48.5%) > Zn (45.8%) > Pb (27.7%) > Cu (21.9%), followed by Sudan grass and Bermuda grass.