| In recent years, due to the rapid growth of China’s copper smelting, and lead to a large number of copper smelting sludge, In order to seek better method of effective recovery of valuable metals in the sludge, the sludge can be harmless, reduction and recycling processing.This thesis mainly from copper smelting formation mechanism and characteristics of the sludge, sludge morphological analysis of heavy metals, the reduction of sludge pyrolysis characteristics, the aspects of high temperature melting solidification sludge were studied. The main research results are as follows:The formation mechanism and characteristics of sludge (neutralizing slag) contained with heavy metals and arsenic from acidic wastewater (waste acid) treatment in copper metallurgy plant were studied by using XRD, ICP-AES, TG-DSC and toxic leaching tests. The modified sequential extraction procedure proposed by the BCR and leaching toxicity test was used to investigate sludge (neutralization sludge and iron-arsenic sludge) in copper metallurgy plant. The experimental results show that: after wastewater treatment, sludge produced was mostly CaSO4·xH2O. The contents of As and Se within sludge leaching solution were obviously higher than those of national standard (GB5085.3-2007) in toxic leaching experiment, indicating that this sludge is one of the hazardous waste. Heavy metals in wastewater treatment process of sludge formation distribution and total amount and leaching is larger.This experiment adopts the continuous heating heating mode, and combination of TG-DSC analysis, Study the reaction mechanism of coal sludge reduction decomposition. The main research results are as follows:Pulverized coal can lead to excessive add in coking and reducing environment impact of sludge reduction, adding too little is bad for sludge reduction; Through each sample decomposition rate considering the sludge and coal powder under the different proportions of calcium sulphate in mixed sample decomposition rate, the choice of the optimal condition is: the sludge/pulverized coal=40/1. Experimental results show that the coal powder calcium sulphate in reducing sludge can obviously increase the SO2concentration;Through the sludge mixed with coal sample analysis of XRD phase after roasting, the temperature at850℃, mainly composed of calcium sulfate decomposition primary reaction; The temperature at900℃, the residue detected in CaS and CaO phase, the temperature SO2concentration severely suppressed, shows that the sludge of calcium sulphate under900℃the main side effects exist at the same time;Temperature reaches1050℃, the main phase in the sludge as the CaO, almost undetectable CaSO4exist at the same time, concentration of SO2instantaneous peak shows that under the temperature of the sludge of calcium sulphate completely decomposed to produce CaO.This experiment using waste incineration fly back to melt solidification method, a study on high temperature melting solidification sludge of copper smelting. The main research results are as follows:the sludge in the sludge residue after1000℃high temperature roasting Sb the leaching amount of3.478mg/L, more than the relevant industry standards of emission standard0.5mg/L; At1100℃to1400℃of sludge after roasting, leaching of heavy metals in molten debris rate are very low, less than GB5085.3-2007emission standards; At1000℃to1200℃temperature range roasting, mainly composed of agglomeration; Roasting temperature reaches1300℃, there are a large number of liquid generated in sludge basically in the molten state, the temperature reaches1400℃, sludge completely fused, formed the dense structure of vitreous; Temperature is the main factor affecting the fixed rate of heavy metals, and the solidification of metals by adding too much SiO2has no obvious effect. |
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