Rotary Kiln For Calcination Dolomite Plant2019-07-13

Summary:The Disadvantages Of Heavy Metal Waste On Cement Rotary Kiln The heavy metals in the kiln from hazardous wastes and conventional raw fuels have a large difference in the proportion of circulation into the atmosphere, clinker and kil…

The Disadvantages Of Heavy Metal Waste On Cement Rotary Kiln

The heavy metals in the kiln from hazardous wastes and conventional raw fuels have a large difference in the proportion of circulation into the atmosphere, clinker and kiln according to different volatilization characteristics. Some predecessors conducted a joint test of cement rotary kiln in the new dry process cement plant, and analyzed the distribution of 13 heavy metals in different phases. The results show that the distribution of heavy metals is not affected by the addition of hazardous waste, non-volatile and semi-volatile. The distribution of the elements in the flue gas is much lower than the distribution rate in the clinker.

The German Cement Research Institute studied the volatilization characteristics of trace elements in the cement rotary kiln system. The results show that the volatile element T1 forms internal circulation and condensation in the preheater to form an external circulation in the kiln ash, generally not entering the clinker and flue gas. However, with the accumulation of internal and external circulation, the emission concentration of Tl in the flue gas after purification will gradually increase. Some researchers have explored the distribution of heavy metals such as cr, As, Pb in the treatment of hazardous waste in cement rotary kiln. The results show that the residual rates of heavy metals in calcined clinker, particulate matter and tail gas are different at different temperatures. Therefore, the types of heavy metals entering the cement rotary kiln and the dosage should be strictly controlled to ensure that the heavy metals in the cement products meet the standards and the exhaust emissions meet the standards.

Heavy metal-containing wastes that are prohibited from entering cement rotary kiln include undisassembled waste batteries, waste appliances and electronic products. Among them, a variety of waste batteries, including zinc-carbon batteries, alkaline manganese batteries, silver oxide batteries, etc., such wastes directly into the cement rotary kiln without dismantling, affecting the stable operation of the cement system, exhaust emissions and cement production and quality. Waste appliances and electronic products should be dismantled and recycled according to their respective characteristics. For hazardous wastes containing heavy metals such as antimony, chromium, copper, zinc, arsenic and cadmium that are not prohibited from entering the cement rotary kiln in the National Hazardous Waste List, controlling the rate of addition of these harmful elements is an important means of pollution control. The maximum allowable dosage is (TI+Cd+Pb+15As) not more than 230mg/kg, (Be+Cr+10Sn+50Sb+cu+Mn+Ni+V) is not more than 1150mg/kg, in actual engineering operation process. The dosage should be strictly controlled to ensure that the limits of relevant standards and specifications are met.

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