Optimization of the Ion Flotation of Dichromate

by Robert B. Grieves,
Gregory A. Ettelt,
J. Schrodt,

Serial Information: Journal of the Sanitary Engineering Division, 1969, Vol. 95, Issue 3, Pg. 515-526

Document Type: Journal Paper


Data obtained with a pilot-plant scale, dissolved-air ion flotation unit, with feed chromium concentrations from 25 mg per 1 to 100 mg per 1 (as Cr2O7) and feed rates from 8 gal per hr to 32 gal per hr, are subjected to multiple regression analysis. Accurate equations relate the fractional flotation of dichromate and of surfactant and the enrichment ratio for dichromate to five independent variables. At the optimum values of the independent variables—polymer dosage 3.2% of the feed dichromate concentration, molar surfactant to dichromate feed ratio of 2.1, 170% recycle, 85 min detention time, and dichromate feed concentration of 100 mg per 1—the chemical operating cost, including surfactant recovery, is 67 cents per pound of chromium. The prime advantage of the process is the concentration of the chromium in a small liquid volume, less than 1% of the feed.

Subject Headings: Chromium | Surface-active agents | Regression analysis | Recycling

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