The Decrease of Waste Oil Viscosity to Save Steam Usage in Cold Rolling Waste Water Treatment Plant of CSC

by Ying-Chieh Liu, Mao-Sung Yeh, Shen-Szu Wang

Publisher - China Steel Corporation, Taiwan.

Category - Engineering & IT

The No.2 cold rolling mill waste water treatment plant is to treat the TCM/PLCM oily waste water. Because oily waste water contains high concentration of silica, iron, and grease, it leads to saponification and agglomeration in the oil separation tank. It caused a high viscosity and high moisture content of oily waste water. This study applied five strategies to solve these problems: (1) selecting the best floating oil softener and dosing concentration in lab; (2) analyzing the function groups, TGA, and NMR to investigate the oil-water separation mechanism; (3) building a pilot plant to do the performance tests; (4) constructing the dosing system of oily waste water with softener; (5) conducting the field tests of floating oil softener. CSC has successfully developed a new floating oil softener to treat the oily waste water. The application of the floating oil softener with 40 mg/L to No.2 cold rolling mill waste water treatment plant can reduce waste oil viscosity from 250~350 dPa·s to 20~30 dPa·s, and moisture content from 85~90 % to 24~27 % at 50℃ in the oil separation tank. Additionally, the waste oil sent to incinerators can be reduced from 230 tons to 170 tons per month. Most importantly, CSC can save NT$7.3 million per year on waste oil processing fees and steam usage costs. The No.2 cold rolling mill waste water treatment plant is to treat the TCM/PLCM oily waste water. Because oily waste water contains high concentration of silica, iron, and grease, it leads to saponification and agglomeration in the oil separation tank. It caused a high viscosity and high moisture content of oily waste water. This study applied five strategies to solve these problems: (1) selecting the best floating oil softener and dosing concentration in lab; (2) analyzing the function groups, TGA, and NMR to investigate the oil-water separation mechanism; (3) building a pilot plant to do the performance tests; (4) constructing the dosing system of oily waste water with softener; (5) conducting the field tests of floating oil softener. CSC has successfully developed a new floating oil softener to treat the oily waste water. The application of the floating oil softener with 40 mg/L to No.2 cold rolling mill waste water treatment plant can reduce waste oil viscosity from 250~350 dPa·s to 20~30 dPa·s, and moisture content from 85~90 % to 24~27 % at 50℃ in the oil separation tank. Additionally, the waste oil sent to incinerators can be reduced from 230 tons to 170 tons per month. Most importantly, CSC can save NT$7.3 million per year on waste oil processing fees and steam usage costs.

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