Recovery of chromium from spent plating solutions by a chromyl chloride process

Conference · Sat Dec 31 04:00:00 EST 1994

OSTI ID:82780

Guddati, S L; Holsen, T M; Selman, J R ^[1]

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1. Illinois Inst. of Technology, Chicago, IL (United States)

A novel chromyl chloride process has been investigated for the recovery of hexavalent chromium from spent plating solutions. In this process chromium is converted to chromyl chloride by reacting it with concentrated hydrochloric acid and then separated as a heavy underlayer, or alternatively, extracted into a solvent as follows: H{sub 2}CrO{sub 4} + 2 HCl {Leftrightarrow} CrO{sub 2}Cl{sub 2} + 2 H{sub 2}O. Purified chromyl chloride is then hydrolyzed and the resulting solution dried and chromium trioxide recovered. H{sub 2}CrO{sub 4} [+ 2 HCl] {Leftrightarrow} CrO{sub 3}{down_arrow} + H{sub 2}O{up_arrow} [+ 2 HCl{up_arrow}]. In preliminary experiments more than 98% of the chromium has been separated as chromyl chloride (without using any solvent) from an aqueous solution which originally contained 200 g/L chromic acid. Temperature and reactant concentrations were found to greatly affect the stability and the yield of chromyl chloride respectively. Equilibrium conditions have been identified using a geochemical equilibrium speciation model. A statistical analysis of experimental results has been performed to quantify the effects of various parameters on the yield of chromyl chloride.

• OSTI ID: 82780
• Report Number(s): CONF-940789--; ISBN 0-7844-0031-8
• Country of Publication: United States
• Language: English

Related Subjects

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION
CHROMIUM
ELECTROPLATING
INDUSTRIAL WASTES
MATERIALS RECOVERY
SEPARATION PROCESSES
TECHNOLOGY ASSESSMENT