Kaolin will produce a large amount of tailings waste after ore beneficiation and recovery. Due to less recycling of kaolin tailings, as the tailings continue to accumulate, they will occupy a large amount of land, pollute water quality, cause vegetation damage and soil erosion, and even cause mudslides, which will seriously affect the ecological environment. Therefore, comprehensive utilization of kaolin tailings and recycling them can effectively prevent waste of resources and damage to the environment.
At present, China’s recycling of kaolin tailings is mainly divided into:
Recovery of valuable components in kaolin tailings
Processing and reuse of kaolin tailings.
Recycling of valuable components in kaolin tailings
The tailings of kaolin often contain a large amount of silicate minerals such as quartz, muscovite, and feldspar. These minerals can be obtained by suitable recovery processes, such as gravity separation, flotation, desliming, etc., to obtain mica concentrates and feldspar concentrates. Ore, quartz concentrate, etc., even beneficiation without tailings can be achieved.
A certain kaolin tailing in Jiangxi Province, China is mainly composed of quartz, muscovite, feldspar and a small amount of kaolinite. Among them, harmful impurities are mainly iron, which are mainly contained in limonite. The classification-flotation process can be used, flotation of muscovite first, and then flotation and separation of feldspar and quartz. Concentrates such as mica, feldspar, and quartz all meet the requirements of technical indicators and realize no tailings beneficiation. Through the recycling of tailings, an additional annual profit of 2.3 million yuan can be achieved.
In the process of comprehensive recycling and utilization of pyrite-rich kaolin, due to the easy siltability of kaolin, fine and fine-grained kaolin have a great influence on the separation of pyrite flotation. Cao Xuepeng comprehensively recycles pyrite-rich kaolin in a certain area. The raw ore contains 79.82% of kaolinite, 18.14% of pyrite and complex inlays. Acidified water glass is used as a regulator and sodium butyl xanthate is used as a catching agent. Collector, through primary roughing, secondary beneficiation, and secondary sweeping, a pyrite concentrate with a sulfur grade of 48.77% and a sulfur recovery rate of 87.30% is obtained. Purification of kaolin after flotation desulfurization reduces the amount of sulfur and iron in the kaolin to a certain extent.
Processing and reuse of kaolin tailings
The main components of kaolin tailings are generally SiO2 and Al2O3. At the same time, it also contains a small amount of K2O, Na2O, CaO, MgO and other components. The characteristics of kaolin tailings can be used as raw materials in some fields.
Using kaolin tailings to replace quartz sand, part of feldspar and other raw materials to produce glass, the amount of kaolin tailings in the formula can reach more than 60%. At the same time, the sericite in the kaolin tailings can reduce the amount of soda ash and reduce the production cost of the product. Kaolin tailings also contain more K2O and Na2O, which has little effect on the viscosity of the glass liquid, but is beneficial to improve the hardness, mechanical strength, thermal stability and chemical stability of glass products.
The researchers compared the physical properties of kaolin tailing sand and natural sand in Maoming area and found that the kaolin tailing sand has finer grains, less firmness, larger angularity, and rougher surface than river sand. Other properties are similar to river sand. Using kaolin tailing sand and natural river sand to prepare C40 and C65 concrete, its performance is obviously improved.
In the context of China’s sustained rapid economic growth, continuous consumption of mineral resources, and increasingly serious environmental problems, many kaolin tailings need to be dealt with urgently. Therefore, it is necessary to improve the research on the comprehensive utilization technology of tailings and turn them into treasures. It will also become a widely used secondary resource, which is also an important way to build a resource-saving and environment-friendly society and achieve sustainable development.