Preparing Composite Inorganic Polymer Flocculant

The blast furnace dust is a kind of solid waste that produced in the process of iron smelting. It is one of the main solid wastes of the steel plant. At present, the steel output of our country have taken the first in the world, and the yield of blast furnace dust is approximately 2 millions of tons per year, when being calculated by 1.7 percent of the number of iron output. Because it is a kind of solid waste in the iron smelting process in large number, the blast furnace dust not only take up much land, pollute environment but also waste a lot of resource if not been reused.We research and product a kind of inorganic polymer flocculant with excellentproperty-PAFC according to the feature of the blast furnace dust . The work hasguiding significance certainly to synthesis application of the blast furnace dust. The research can not only solve the environmental pollution caused by the blast furnace dust , but also obtain useful resource. In the paper, a new method is found for the reuse of the blast furnace dust.According to the different content of iron and aluminum in the blast furnace dust, the optimum experimental condition that can reach the highest dissolution ratio of iron and aluminum is obtained by a number of experiments. On the basis of those experiments' results and the different hydrolytic features of iron and aluminum, a kindof inorganic high polymer flocculant-PAFC is synthesized by controlling thehydrolytic reaction conditions. At the same time, kaoline water and brewing wastewater are treated by PAFC and the disposing results are good.The main results are: (1) The dissolution ratio of iron and aluminum in the blast furnace dust dissolving by hydrochloric acid is higher than that of sulfuric acid. As a result, hydrochloric acid is selected as the proper dissolvent of the blast furnace dust. (2) The dissolution ratio of iron and aluminum can reach 67.61 percent and 12.35 percent respectively when the experimental temperature is controlled at 100℃, the reacting time is 3 hours, and the mixing ratio of the blast furnace dust and the hydrochloric acid is 1:3. (3) Compare Al(OH)₃ with the solution of Na₂CO₃ as regulator of pH, we find out that PAFC with better stability and higher turbidityremoval ratio can be synthesized with Al(0H)3 as regulator. (4) On the basis of the optimum condition of the dissolving experiment, add A1(OH)3 to neutralize the pH of the dissolution of blast furnace dust, preserve the hydrolytic temperature of 60^<sup>70°C for 4 hours, under those conditions, PAFC with better stability and higher turbidity removal ratio can be synthesized. And the turbidity removal ratio of kaoline water can reach 99.36 percent. (5) The SS and CODcr removal ratio of brewing wastewater can reach 90 percent and 45 percent respectively when the dosage of PAFC is in the limit of 40^<sup>50mg/L , pH is in the limit of 8-—10, and the sedimentation time is in the limit of40⁵0min.