Development of Measures for the Minimization of Chromium(VI) Compounds in Sewage of Production of Asbestos-Cement Products

Abstract

The revelation of the appearance and accumulation of hexavalent chromium ions in sewage of asbestos-cement products and development of manufacturing solutions
to minimize the ingress of hexavalent chromium into the surrounding medium during the industrial production are considered. It is established that the main
source of hexavalent chromium ions in sewage of asbestos-cement products is the clay of the Michurinsk deposit, one of cement components. Baking the cement
raw materials leads to oxidation of Cr3+ into Cr6+ in the presence of potassium and sodium oxides and sulfates. When using the recuperation water, Cr6+ ions gradually
accumulate in it. A method for removing hexavalent chromium ion from sewage of production of asbestos-cement products with the use of iron vitriol is recommended
and introduced. With the continuous introduction of the 20-% iron sulfate solution with a rate of 300 cm3/min into the sewage of production of asbestoscement
products made it possible to reduce the hexavalent chromium content from 14.0 to 3.4 mg/dm3. The development of such closed water management system
enabled ones to exclude the sewage discharge into basins and reduce the consumption of fresh water.