Pyrite-rich cyanide tailings (CTs) are industrial hazardous solid wastes arising from the gold mining industry. Every year, hundreds of millions of tons of cyanide tailings are produced and discharged to tailings dams. It is of great significance to dispose of cyanide tailings harmlessly and resourcefully. The feasibility of calcination of calcium sulphoaluminate (CSA) cement clinker using pyrite-rich cyanide tailings as Fe₂O₃ and SO₃ sources was investigated for this paper. The behavior of pyrite during the calcination of cyanide tailings under various calcination conditions and the properties of calcium sulphoaluminate cement clinker were examined. The results show that it is feasible to produce calcium sulphoaluminate cement clinker using pyrite-rich cyanide tailings. The optimal conditions for the calcination of calcium sulphoaluminate cement using pyrite-rich cyanide tailings are confirmed. During the calcination process, the cyanides decompose into carbonate, CO₂, and N₂. The pyrite decomposes into Fe₂O₃ and SO₂, and they react with CaO and Al₂O₃ to form the intermediates of CaSO₄, 2CaO·Fe₂O₃, and CaO·2Al₂O₃, which further react to form 3CaO·3Al₂O₃·CaSO₄, 4CaO·Al₂O₃·Fe₂O₃, and 12CaO·7Al₂O₃. The calcium sulphoaluminate cement prepared by pyrite-rich cyanide tailings exhibits excellent mechanical properties and meets the compressive strength criteria of 42.5 grade calcium sulphoaluminate cement.

The dissolution routes of chalcopyrite in acidic sulfate aqueous solution have been discussed by thermodynamic calculation under different aqueous species concentrations, such as Cu²⁺, Fe²⁺ and H₂S. The results show that for both oxidative dissolution and non-oxidative dissolution of chalcopyrite, the dissolution process undergoes several intermediate steps before completely decomposing to Cu²⁺, Fe²⁺ and elemental sulfur, in which bornite and covellite are the most likely intermediates. The dissolution routes of the secondary intermediates have also been discussed and covellite is the most likely final intermediate. Based on these results, some frequently reported phenomena, such as the existence of an optima redox potential range, the promotive action of the addition of Cu²⁺ and Fe²⁺ , as well as the preferential release of Fe²⁺ in the chalcopyrite leaching process, have been explained and elucidated.

The potential use of emulsion liquid membranes (ELMs) with LIX 7950 as the mobile carrier to remove heavy metals from waste cyanide solutions has been proposed. Relatively stable ELMs with reasonable leakage and swelling can be formed under suitable mixing time and speed during emulsification. The concentration of LIX 7950 and Span 80 in the membrane phase, KOH in the internal phase and the volume ratio of membrane to internal phases are also critical to ELM formation. The efficiency of copper and cyanide removal from dilute cyanide solution by ELMs is related to ELM stability to some extent. More than 90% copper and cyanide can be removed from dilute cyanide solutions by ELMs formed under suitable experimental conditions.

In this work, a mineralogical study and thermal decomposition analysis of jarosite residue sample from a zinc plant were carried out. The mineralogical analysis showed that the jarosite residue is mainly composed of four components, including jarosites, sulfates–hydroxides, sulfides and spinel. The distribution of relevant metallic elements in these components was characterized using a sequential extraction process. The X-ray diffraction results showed that AFe₃(OH)₆(SO₄)₂ and ZnFe₂O₄ are the main components of the jarosite residue sample. The thermal decomposition mechanisms of ammoniojarosite and sodium jarosite were studied by TG-DSC (Thermogravimetric analysis–differential scanning calorimetry). The thermal decomposition process and the corresponding mechanism of the jarosite residue were analyzed. The jarosite thermal decomposition process includes the removal of crystal water, dihydroxylation and deammoniation, desulfonation of component jarosite and desulfonation of component zinc sulfate.