Technology Research Of Re-use Of Blast Furnace Gas Washing Water

With a quick development of our country's industry, water pollution has turned out to be increasingly serious. And the short of water resources is becoming one of bottlenecks in a sustained development of our country's economy. Re-use of treated polluted and waste water of industry is one of the most effective methods to solve and relieve the water problems mentioned above. In order to have a cycle use of the blast furnace gas washing water of Baogang, the paper has systematically investigated and studied the existent blast furnace gas washing water-processing system in Baogang, resulting in as following:1. Based on the performance and practice of blast furnace gas washing water processing systems form various steel enterprises home and abroad, present development situation of treatment technology of concrete precipitate of blast furnace gas washing water is analyzed; on the blast furnace gas washing water-processing system in Baogang, Experiments of static and dynamic concrete precipitating have been carried on, having chosen poly Ferro, Polyacrylamide, lime compound concrete agent as the best concrete agent to treat the blast furnace gas washing water and having proved that the best blending rate of the compound concrete agent as well as the best operating parameters: poly Ferro sulphate 10 mg/L, Polyacrylamide 0.1 mg/L, lime 25～250 mg/L; pH = about 8.5; remaining time in precipitating tank: 1.5h; remaining time in mixing trough: 2mm; remaining time in reacting trough: 10 min.2.Under the best operating situation: out water suspended substance (SS) is lower than 120 mg/L with removing rate of about 93%; out water organic substance (COD) is lower than 30 mg/L with removing rate of about 96%; both above have met the requirement of blast furnace washing water quality the index of which is that SS is less than 120 mg/L. The research has proved that the quality of the processed washing water totally meets the requirement of blast furnace washing water.3.The closed cycle use of the processed blast furnace gas washing water is basically realized, but at same time, the serious subsequence of increased incrustation forming in the system is coming out. Therefore, the research has been done for prevention of the incrustation forming and the conclusion is that: Based on the dynamic experiment, after the treatment of the concrete precipitating with the fed in Poly Ferro, Polyacrylamide and lime as the compound concrete agent, 25ppm of water quality stabilizing agent XF-B-01 is put in. By doing this, the treatment of calcium and magnesium incrustation forming in the Baogang blast furnace gas washing water system becomes quite effective having decreased the speed of incrustation, and on the other hand, effect of dispersion and stabilization of zinc comes into being with gradually getting rid of zinc incrustation as a result.4. Improvement of the treatment technology of sludge in blast furnace gas washing water is made and feasible measures of increasing operating efficiency of the squeezing strainer is implemented saving 20 strainer cores annually, keeping the strainer working for 600 hours without any interruption monthly and reaching a level of output of 4500 tons of sludge per month.