Hematite Process to Treat Zinc Sulfide Concentrate from Lanping Lead–Zinc Mine Area, China

In the Lanping lead–zinc mine area, hazardous jarosite residue produced by the jarosite process seriously threatens the remaining capacity of the tailings pond and the local ecological environment. Therefore, the hematite process has been recommended as an alternative to the jarosite process to overcome the challenge of the hazardous jarosite residue. The recommended reaction conditions for the hematite process are: initial pH = 3.0–4.5, reaction temperature = 150°C, oxygen partial pressure = 0.4 MPa, agitation speed = 500 rpm, and reaction time = 3 h. For the zinc leaching solution containing about 19 g/L Fe 2+ , the Fe concentration after iron removal via the hematite process was reduced to 2 g/L, and the corresponding iron removal efficiency reached 89%. The Fe content in the hematite product is higher than 55%, and the Zn loss and S pollution in the hematite products were below 1% and 3%, respectively. According to the China Non-Ferrous Metals Association for group standard (T/CNIA 0147-2022), the hematite products produced in this study reached the third grade and can be sold as steelmaking raw materials. Therefore, iron ions in zinc leaching solution can be resourced through the hematite process so as to avoid the stockpiling of iron removal residue. The challenges posed by the limited storage capacity of the tailings pond and the threat of jarosite residue to the local ecology can thus be perfectly solved.