Separation of alumina from the paint sludge of automotive industry by leaching method

Paint sludge of automotive industries, due to having heavy metals, unbaked polymers, organic and inorganic pollutants, has been classified as a hazardous waste. For this reason, its proper disposal is faced with many problems. Various methods yet have been developed by the great automobile companies of the world to reduce the environmental impacts of paint sludge. One of the effective an economical methods for reduction of pollution is separation of heavy metals from paint sludge. The present study was carried out to investigate the pollution of paint sludge from automotive industry, to reduce its pollution to environmental standard levels, and to recover alumina from the paint sludge through leaching method. After XRD and XRF tests on paint sludge, it was found that the amount of alumina is relatively high. Separation of alumina was considered because of its economic value and various applications in different industries. After utilizing the common separation methods, it was revealed that by optimizing the parameters such as temperature, sludge particle size, and sulfuric acid concentration through the leaching method, about 70% of alumina can be recovered.