Accumulation of gypsum waste generated in the global production of phosphate fertilizers, is about 180 million tons per year, which is considerably higher than the annual production of natural gypsum, located at the level of 100-120 million tons per year. Also, gypsum waste generated in the production of fluorine compounds, titanium, boron, and the purification of industrial gases from sulfur. This technology-related resource is a source of raw materials for a variety of chemical products. Meanwhile it remains untapped industry and create significant environmental problems associated with its accumulation of a large scale. At present the issue of utilization of such waste is one of the most serious problems of chemical industry.
In the North-West region of most perspective is the processing of technology-related gypsum of conversion method, to yield a primary production of ammonium sulfate and calcium carbonate. Both products are mineral fertilizers used in agriculture. Of additional interest is the use produced calcium carbonate because of its high reactivity in the production of cements, coagulants, sealants, reagents for the chemical treatment of water and industrial solutions. These directions were investigated at the Department of Metallurgy Mining University. National mineral resources university with the participation of "FOSAGRO Cherepovets" was done technological development for the processing of gypsum waste that will create a pilot plant for the recycling of gypsum waste of the company. Unit operations allowed to identify the main technical and economic characteristics of developed technology that forms the basis for its development on an industrial scale. Thus on 1 ton of technology-related gypsum product yield provided in an amount of 0.78 tons of ammonium sulphate and 0.48 tons chemically precipitated calcium carbonate. The degree of utilization of gypsum is about 99%, which prevents the formation of new waste.
The new technology provides:
- Improving the environmental safety of production of mineral fertilizers, because of decrease of pollution surrounding areas, including localities, water and air;
- Increasing the complexity of the processing of mineral raw materials of natural origin and filling needs in primary resource production waste products;
- Increase of production volume of agricultural fertilizers;
- Possibility to obtain calcium carbonate suitable for use in metallurgy, chemical engineering and building materials.