Dioxins, is by far the most human carcinogenic potential of discovered material, great harm to the environment and human, we must attach great importance to the prevention and treatment issues. Metallurgical industry is a persistent organic pollutant emissions from the main source of the sintering process in which iron and steel industry is to generate more production units of dioxin. Control of dioxin produced in sintering process issues, from the following aspects:
- Sintered material choice: the generation of dioxin according to the sintering causes the presence of chlorine in the sintering process is an important factor in the formation of dioxins one. Therefore, the best raw materials with low chlorine elements. Iron oxide dust and rolling because the chlorine content of the skin is relatively high and rolling by changing the dust mixed with the proportion of oxide scale can change the mixture of the raw material sintering chlorine content. In addition, the materials in the presence of copper may have a catalytic formation of dioxins, certain types of iron ore may be a major source of copper, iron ore is very important to choose the right. A higher sulfur content of fuel and iron ore can significantly reduce dioxin formation. First, the principle of reducing the catalytic activity of copper; Second, consumption of chlorine source, weakening the role of aromatic chlorinated compounds.
- Process Control: dioxins in the sintering process is mainly generated in the material layer, to reduce the sintering process of the formation of dioxins, should improve the conditions of sinter layer, to minimize the formation of gaseous HC1, inhibit the production of generated during the fly ash to prevent the re-formation of dioxins precursor compounds and other compounds. The use of gas in the sintering cycle, can significantly reduce the amount of emissions of dioxins, but also reduce emissions of nitrogen oxides during sintering of gas and dust content. Parts of the large amount of dioxin generated some of the exhaust bellows back as sintering combustion air can not only save energy, but also can significantly reduce dioxin formation, this reduction technique has been applied abroad, such as the European Cruise sintering machine to all adopted this technology, 50% of the waste is recycled, dioxin emissions reductions reached 70%, particulate matter and nitrogen oxide gas emissions nearly 45% of heavy volume.
- Add inhibitors: The results show that adding to the solid-state sintering bed inhibitor - urea particles, can significantly lower the sintering flue gas emission concentration of dioxins, dioxin inhibited the formation of a significant effect. Corus UK company (CorusUK) by testing to determine the optimum amount of urea, can reduce dioxin emissions by 50% without a significant increase in emissions of particulate matter and ammonia gas concentration, the increase in the cost of about every 0.03 tonnes of sinter. This technology is considered the most economical dioxin inhibition technology. In addition, the use of activated carbon adsorption, gas cleaning equipment to handle the sintering exhaust gas, can reduce the concentration of dioxin emissions, while reducing sulfur and nitrogen oxide gases and other pollutants. Sintered compound is also adding an appropriate amount of ammonia can significantly reduce dioxin formation. Ammonia from the coking system can be low cost. Near the discharge end can be sprayed into the bellows a few, but the location should be injected into the sinter layer near the bottom and not sprayed into the air tubes, or nearby. Korean Pohang studies have shown that injected into the sinter layer of sodium bicarbonate, can significantly reduce the amount of dioxin produced, the principle may be sodium bicarbonate and sintering processes of the reaction of gaseous chlorine, which can generate dioxin reduction The chlorine source. In addition, you can spray into the air inside the sodium hydroxide, magnesium hydroxide or calcium hydroxide mist, the smoke quickly cooled to below 200 ? easily reduce dioxin formation in flue gas residence time of the temperature range, can significantly reduce dioxin formation, the injection part of it is the closer the better sinter layer.