Recycling of Dewatered Sludges From Rolling Mills by Microwave Extraction / Jittiporn Kulpisitthicharoen

Abstract

Sludge from iron rolling mills is considered one of problematic industrial waste. In Thailand, the industrial rolling mill sludge is produced more than 20,000 metric tons per year and generally is disposed of in sanitary landifill. This research focused on recycling of dewatered sludge from hot and cold rolling mills by microwave extraction. The various temperature programming at 90, 120 and 150 C and the different solvents such as acetone, N-hexane, petroleum ether and a mixture of acetone with N-hexane in 1:1 (volume/volume) ratio were studied in order to determine the optimum condition for oil extraction from dewatered sludge by microwave. Based on the results from the study for both hot rolling mill and cold rolling mill cases, it was found the the average value of extracted oil of 28.83% as dry sludge basis was obtained under the proper condition of microwave temperature programming at 150 C and using the mixture of acetone and N-Hexane as extraction solvent. The average calorific value of 9,965 calories per gram of extracted oil which is acceptable for using as fuel in cement kiln was yield. Iron and other materials of 78.4% and 21.6% by average, respectively, were the components of solid residue after extraction, Regarding the cost of oil extraction by microwave obtained from the entire experimental runs, it was varied between 0.27 and 8.01 Baht per gram of obtained extracted oil.