Effect of the Thermal Utilization of Wastewater Sludges in the Coal Carbonization Process on the CRI/CSR Quality Indices of the Coke

摘要

(1) The study on the use of the dewatered sludge resulting from the treatment of municipal wastewaters as an additive to coal charge allowed us to establish the following facts: When 4 percent of sludge was added, no decrease in the CRI and CSR indices of the coke was found, implying that the addition of sludge in this amount can be regarded acceptable. When more than 4 percent is added, it is necessary to consider the decrease in both coke quality indices. The content of ash in the coke is increased by 0.15 percent for every l percent, increase in the content of sludge in the coking charge. Increasing the amount of wastewater sludge in coal charge causes an increase in the m6isture content of the charge by about 0.65 percent for every 1 percent increase in the weight fraction of the sludge, which leads to the following technological consequences: longer coking times, or higher temperatures of coking-chamber heating walls, and increased amounts of excessive ammonia liquor. The results of the study imply that the content of dewatered sludges of municipal wastewaters in coal charge should not exceed 4 percent. The attempts taken in industrial by-product coke oven plants to utilize waste-water sludges in the coking process are limited by the necessity of utilizing their own wastes because of the high requirements for the quality of the products of the metallurgical industry and the high requirements of environmental protection agency codes.