LIME COMPONENT REGENERATION AND RECYCLING IN CHEMICAL-METALLURGICAL TECHNOLOGIES

References: 17th International Multidisciplinary Scientific GeoConference SGEM 2017, www.sgem.org, SGEM2017 Conference Proceedings, ISBN 978-619-7408-06-5 / ISSN 1314-2704, 29 June - 5 July, 2017, Vol. 17, Issue 41, 185-192 pp, DOI: 10.5593/sgem2017/41/S18.024

ABSTRACT

The problems of regeneration and recycling of the calcareous component in the composition of chemical and metallurgical industry waste products are studied. The possibility of obtaining chemically precipitated calcium carbonate from gypsum wastes and slimes of alumina production is shown on the basis of a number of low-temperature processes that ensure binding of carbon dioxide as part of production emissions. The influence of quality of raw materials on the volume of belite sludge which is formed during the processing of alkali aluminosilicates is established. During research was established that it is possible to increase the depth of nepheline raw materials processing and to balance the amount of portland cement clinker produced at the expense of improving the enrichment of the feedstock, as well as increasing the throughout recovery of alumina, and also by conversion processing of nepheline (belite) sludge. The coherency between the degree of conversion of belite and the total volume of nepheline sludge which is needed to be processed to produce one-component portland cement raw meal was determined. The mechanism of soda conversion and its parameters are determined depending on the duration of the process, temperature and concentration of the soda liquor. While taking into account high concentration of soda-alkaline liquor was established the stoichiometry of compound conversion process accompanied by formation of sodium metasilicate which is stable under these conditions. Causes of soda conversion degree reduction associated with high indicators of causticization and deposition of sodium and calcium double carbonates are shown. Proposals were made to increase the conversion degree due to carbonization of formed caustic alkali. The mechanism of belite interaction which includes formation of solid products and causes diffusion resistance to mass transfer growth is substantiated. The process of chemical and mechanical surface activation of reacting agents was proposed.

Keywords: recycling, regeneration, lime component, nepheline sludge, hydrochemical conversion.