Lead and Zinc Smelting Flue Gas Treatment
Flue gas produced by smelting lead and zinc not only produces dust, but also reduces air quality. In order for lead and zinc industries to meet the requirements of environmental protection, it is necessary to control the emissions of SO2, NOx and other pollutants from lead and zinc smelting flue gas.
DeSOx
The most important role in treating lead and zinc flue gas is the removal of sulfur dioxide (SO₂). SO₂ is mainly removed by using wet desulfurization. Wet desulfurization is to spray a desulfurizing agent into the flue gas, SO₂ and the desulfurizing agent react in the contact area of the reaction, and then are absorbed by the scrubbing liquid. Common desulfurizing agents are limestone slurry, sodium and calcium-based absorbents.
DeNOx
The main methods for the treatment of nitrogen oxides (NOx) in lead and zinc smelting flue gas are SNCR and SCR.
SNCR uses reductants such as ammonia or urea to react with NOx at high temperature to reduce the emissions of NOx. SNCR is a low-cost and reasonably effective method of desulphurization, but the desulphurization efficiency is limited.
SCR uses urea or ammonia and oxygen as a catalyst to reduce NOx emissions. It has the advantages of high desulfurization efficiency, high applicability and wide range of application. The disadvantages are that the investment is large, the process is complicated and there is a large amount of water needed.
Dust Removal
Lead and zinc smelting flue gas contains more dust, mainly using ESP and bag filter, ESP uses high-voltage electric field to attract flue gas dust through high-pressure fan suction, and deposits it on the top of the collecting plate.
Bag filter collectors are also commonly used. Bag filter collectors are suitable for the purification of particles in gases. When the flue gas is passed through a filter, the fibrous material of the filter is used to capture particle dust from the flue gas and satisfy the demand for lower dust collection.
Conclusion
Lead and zinc smelting flue gas treatment includes deSOx, deNOx, and dust removal. Wet desulfurization is the main way to remove SO₂, nitrous oxides are mainly removed by SNCR or SCR, and ESP or bag filter collectors can be used for dust removal. It is important for lead and zinc industries to meet the requirements of environmental protection, and proper control of emissions from lead and zinc smelting flue gas is the key to reducing environmental pollution.
