A method of reprocessing coal slag and ash into granulate for the building industry in a combined wasteless aggregate – steam-generator/melting-converter was developed and tested. The method involves melting slag and ash from coal-fired team-generators of thermal-power plants in a melting-converter located under a steam-generator with direct slag drain from the steam-generator combustion chamber. The direct drain of slag into the converter allows burn-up of coal with high ash levels in the steam generator without an additional source of ignition (natural gas, heating oil, etc.).
Specific to the melting process is the use of a gasair mixture with direct combustion inside a melt. This feature provides melt bubbling and helps to achieve maximum heat transfer from combustion products to the melt to improve mixing, to increase rate of chemical reactions and to improve conditions for burning the carbon residue from the slag and ash.
The “gross” thermal efficiency of the combined aggregate is about 93% and the converter capacity is about 10.8 tons of melt per hour.
The experimental data for different aspects of the proposed method are presented. The effective ash/charging materials feeding system is also discussed.
The reprocessed coal ash and slag in the form of granules can be used as fillers for concretes and as additives in the production of cement, bricks and other building materials.
