Complex reprocessing of industrial alkaline waste of alumina production (red mud) for solving raw materials and environmental problems

Red mud are industrial large-scale toxic wastes of bauxite ore processing according to the Bayer method. They contain macrocomponents such as iron, aluminum, calcium, silicon, as well as a number of the most valuable and critical metals (microcomponents): scandium, gallium, germanium and rare earth elements (REEs), which are used in modern high-tech industry. Due to the relatively high content of scandium and REEs, red mud can be considered as a promising secondary source. Significant amounts of accumulated red mud and new flows of this waste entering the slime storage facilities need to be processed to obtaine the required valuable products. Development of complex reprocessing approach play an important role in addressing the problem of the elimination of red mud as toxic waste. Within the framework of this subject, the report considers the concept of complex reprocessing of Bogoslovsky Aluminum Plant (Russia) red mud, which includes the extraction of aluminum, scandium, REEs, zirconium and the production of iron-containing concentrate for ferrous metallurgy. The use of low-aggressive carbonate media and carbonation method using carbon dioxide gas characterizes this approach as more environmentally and technologically safe. The development of effective technology for utilization of red mud will not only provide a source of critical raw materials, but also solve the global environmental problem

Current key options for management of industrial alkaline waste of alumina production (red mud)

Due to the ever-increasing demand of the world economy for aluminum, its alloys and compounds, the production of this metal is increasing annually throughout the world. This leads to an increase in the industrial production of alumina, which is obtained from bauxite ore in the Bayer process. After recovering the bulk of the aluminum from the bauxite ore, there remains a residue which is highly alkaline toxic waste, which is also called bauxite residues (tailings) or red mud (RM). About 140-150 million tons of RM are produced annually and almost 4 billion tons have already been accumulated. At the moment, the problem of RM recycling and the development of effective and cost-effective approaches to their reprocessing is extremely urgent. Reducing RM affects economic, environmental, social areas and is a prerequisite for the sustainable development of nature and society. Despite active scientific research and efforts to develop and optimize various methods for RM recycling and reprocessing, the problem of an annual increase in their volumes around the world remains unresolved. Recently, promising and efficient processes have been proposed that allows for the complex reprocessing of RM with the extraction of a number of valuable liquid products that may be in demand in various fields of industry. This allows to focus on large-scale disposal of RM and can be a solution to the problem of handling these industrial wastes. The article considers the main current trends in the field of management of various types of RM with a focus on complex reprocessing and zero waste concepts