Research progress of chlorination roasting of heavy metals in solid waste

Both developed and developing countries are producing a large amount of heavy metal solid waste, such as municipal sludge, waste incineration fly ash, tailings, metallurgical and chemical solid waste, and electronic waste. In the process of transferring and disposing these heavy metal-containing wastes, the exposure of heavy metals will cause a very serious impact on human health and the ecological environment. Due to the shortage of resources as well as the need of circular economy, there is an urgent need to recover materials from solid waste efficiently and economically by advanced treatment technology. Chlorination roasting technology is a smelting process that uses the principle of chlorination metallurgy to recover valuable metals from solid waste. It has the characteristics of strong applicability of raw materials, high separation efficiency and good comprehensive recovery effect. However, the application of chlorination roasting technology in heavy metal solid waste still lacks a comprehensive and systematic understanding, which hinders the promotion of this technology. This review summarizes the application status of chlorination roasting technology in the extraction of metals from four typical solid wastes, including tailings solid waste, electronic solid waste, municipal solid waste and industrial solid waste. We not only make in-depth analysis of the transformation process of metal elements (toxic metals, rare precious metals) in solid waste during the chlorination roasting process, but also summarize the proposed mechanisms of chlorination roasting. Finally, based on the comprehensive discussions above, we provide some the methods for enhancing the effect of chlorination roasting and design a much more efficient metal recovery process.