A Study on Reuse of Slag Containing Hexavalent Chromium.

概要

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A process for stabilization hexavalent chromium, which is a wet treatment process for chromium-containing slag, utilizing formation of hardly soluble chromate has been studied. In this process, when the treatment is carried out with steam at a pressure of 8 kg/cm2and a temperature of 175°C for 8 hours, MgO in the spent slag was almost completely converted to Mg (OH) 2, and the presence of MgO leads to the problem of volumeswelling of the slag. The steam-treated slag was treated at a temperature of 80°C by mixing the slag with water at a ratio of 1: 2 (w: w) at an elution time of 20 minutes to allow hexavalent chromium in the slag to be eluted into the aqueous phase. The elution ratio in the first treatment attained to 80%. The eluted hexavalent chromium solution can be isolated as a chromium yellow pigment to be reused as the raw materials for the pigment. The slag obtained after eluting hexavalent chromium was mixed with a 8% BaCl2solution to convert a trace amount of hexavalent chromium remaining in the slag to hardly soluble BaCrO4. The slag after the treatment can be reused as construction materials.
環境技術学会の論文