Currently, industrial enterprises of various profiles produce a huge amount of gypsum-containing waste. It is not surprising that researchers and industrialists pay great attention to the problem of recycling and processing gypsum waste.
One of the most promising approaches to the problem of processing gypsum waste is the development and implementation in production of technologies for the production of gypsum binders from them, which are in demand in construction industries. The implementation of this approach will significantly reduce pollution of soil and air, water bodies and groundwater. In many regions of Russia that do not have their own gypsum deposits, this will not only have a favorable impact on the environment, but will also provide local construction industries with raw materials at a lower price than those brought from other regions (long-distance transportation of gypsum significantly increases its cost).
Phosphogypsum, borogypsum, fluorogypsum are sent for processing. As the main process, cooking in liquid media is used. If gypsum waste contains too many impurities (more than 0.5%), especially phosphorus or fluorine, which can significantly reduce the quality of the binder, then the raw material undergoes preliminary washing. The processing of citrogypsum, a waste product from citric acid production, is of great technological complexity. And the most common type of gypsum waste is phosphogypsum, a by-product of the processing of phosphorite and apatite ores - for example, in the production of one ton of superphosphate, one of the most popular agricultural fertilizers, four tons of phosphogypsum is formed.
Specialists offer various processing methods - both oriented to energy-intensive technologies, and more economical autoclave-free methods based on the water-taking effect of sulfuric acid. As a rule, processing technologies involve obtaining modified gypsum binders that are more in demand by the industry. Modifications are mainly made to the water resistance index of gypsum.
Despite the fact that processing technologies are constantly developing, and more and more enterprises are introducing them to one degree or another in their production, processing and reuse of gypsum waste is far from the full cycle - in most regions gypsum waste continues to accumulate.