Complex processing of ash and slag wastes from coal-fired CHP plants

Abstract

The paper focuses on both Russian and international practices concerning the solution of ash and slag wastes processing and prospective areas of their application. The results of lab and pilot plant tests on concentration ability of ash and slag wastes which were obtained during coal combustion at coal-fired CHP plants of Irkutskenergo JSC (Irkutsk, Russia) are presented. Ash and slag wastes, themselves a product generated by high-temperature thermal processing of the mineral matter of the coal during combustion in boilers, are a gray grainy mass. Dozens of ash and slag wastes millions of tons which generate annually during coal combustion at coal-fired power plants of the Irkutsk region can be fully processed with the generation of saleable products: iron concentrate, aluminum silicate product as well as products containing rare-earth, sparse and precious elements. In this case, ash and slag wastes processing can be disposable. Pilot plant tests confirmed lab tests results in terms of the quality of the resulting iron-bearing concentrate and aluminum silicate product. The mass yield of iron-bearing concentrate and aluminum silicate product in terms of ash and slag volume was 3-9% and 40-60%, respectively. Lab and pilot plant tests conducted demonstrated viability of the ash and slag wastes efficient processing. This resulted in their complete recycling and reduction in the environmental impact combined with profit generation from selling saleable products. Economic calculations showed that the payback period for the construction of an ash and slag wastes concentration plant with the throughput of 1.0 MTPA is 2 years. The production line is equipped with environmentally friendly equipment produced in Russia.