Local treatment of coal-water slurries from thermal power plants with the use of coagulants

Abstract

The coagulation of coal particles in a coal-water slurry from the Novo-Irkutsk thermal power plant was studied. The advisability of the application of highly basic aluminum hydroxochloride of grade B for the treatment of contaminated water with a concentration of suspended particles of 30 g/dm3 was shown. The granulometric analysis of coal particles was performed. The application of the reagent was revealed to be efficient for the coagulation of both coarse particles and a finely dispersed fraction. Carbonate hardness values of up to 1.5 mmol-equiv/dm3 and pH ≤ 7.8 were shown to be typical for the contaminated water from the fuel supply shop. They were the most optimal parameters for hydrolysis and efficient flocculation and did not require the addition of sodium bicarbonate and flocculants. The process flowsheet of the separate purification of a coal-water slurry was developed for the fuel supply shop. Among the advantages of this purification method are the return of rather highly purified water for thermal power plant needs, and also the production of additional fuel in the form of recovered coal particles. The product was characterized by improved engineering parameters in comparison with the initial fuel, i.e., had a higher calorific value and a lower sulfur content. The purified water corresponded to the normative requirements to the content of residual aluminum. This technology of purification was resource-saving, environmental-friendly, and economically profitable.