Use of polyacrylamide in the steel and power industries
According to the relevant information, the PAM used in the steel industry is mainly an anionic product, which is suitable for liquids with positive charges on the ionic surface, which can be effectively used for sedimentation separation of mineral suspensions. The water to be treated is suitable when the pH is neutral to alkaline and contains a large amount of inorganic suspension. In the water treatment, in addition to the use of ironmaking blast furnace, aluminum processing, papermaking, river sand washing and other wastewater treatment, it is also used in the city sewage treatment.
In the steel industry, the precipitation treatment of blast furnace gas washing water must use PAM. For example, WISCO, Bengang and other plants use coagulation sedimentation. The design index of blast furnace gas washing water is: adding polyacrylamide 0.5mg/l, sedimentation tank effluent suspension ≤ 50 mg / l. Bengang's precipitation efficiency of inorganic and organic polymer flocculants is 98%. The Institute of Building Research of the Ministry of Metallurgy and the Shougang Design Institute conducted an experimental study on the coagulation and sedimentation of Shougang blast furnace gas washing water, and determined the precipitation effect of a single coagulant and a composite coagulant. Experiments showed that polyacrylamide was used. 0.3mg/l) coagulation and sedimentation can achieve a sedimentation efficiency of more than 90%. When the cycle time is long and the cycle rate is high, polyacrylamide and a small amount of ferric chloride or basic polyaluminum chloride can be combined. The enriched fine particles are removed.
In order to accelerate the sedimentation of suspended particles and adjust the pH value of the sewage, a polymer coagulant such as a polymer coagulant and a sulfuric acid or a spent caustic solution is added to the distribution tank. The average SS before water treatment was 5000 mg/l, 200 mg/l after treatment, 50 mg/l when PAM was added, and the dosage was 1-5 mg/l. Benxi Iron and Steel Co., Ltd. dedusting circulating water treatment, sedimentation, sludge concentration, dehydration and other processes, PAM for sludge dewatering uses Fushun Liuhua products, the consumption is 500g per ton of dry mud. Shougang recycles 40,000 tons of sludge per year, and the internal price is 23 yuan/ton. Angang annually recovers 90,000 tons of sludge, and the internal price is 13.5 yuan/ton (90-year data).
It is understood that there are currently 56 local steel enterprises and more than 10 state-owned large-scale iron and steel enterprises, which are huge market resources.
In the power industry, PAM can be used to treat plant water. In the treatment of water in power plants, the raw water (such as river water) should first be clarified. A common method is to use PAM together with an inorganic coagulant such as lime, aluminum sulfate, and polyaluminum. Because, if an inorganic coagulant is used alone, a high concentration is required to be effective, and after the PAM is used, the inorganic coagulant can be greatly reduced. This can prevent the inorganic coagulant from being easily deposited on the heat exchange surface of the cooling tower or the like due to the large amount, thereby accelerating the corrosion and scaling of the equipment.
The dust control of coal-fired power plant boilers adopts four categories: electric precipitator, bag type dust collector, wet type dust collector and cyclone dust collector. The main types of wet dust collectors are: water film dust collector, iron bar grating dust collector and venturi pipe dust collector. . Wet dust removal wastewater needs to be settled with PAM. At present, the use of wet dust collectors in coal-fired power plants nationwide is the three major power grids in Northeast China, North China and Central China.