Preparation Of Alumina Grinding Ball With Waste Slag Of Aluminum Factory

A great deal of milky colloidal solution is produced during the surface treating procedure of aluminum factory, which is usually precipitated and filtered to form a solid state material called waste slag. To solve the existing problems of the alumina production such as the high cost and high energy consumption,waste aluminum slag as a substitute for commercial alumina was first time used as main raw material with clay,talc and barium carbonate in this thesis to make alumina grinding ball,which was subtask national 863 project. No patents and reports about the preparation of the alumina grinding ball by using the waste sludge of aluminum factory had been found through online serach both domestic and abroad. Therefore, this project is an innovative one in raw materials and it has good economic and social returns.We have applied to national patent for invention and will possess independent intellectual property in this area. This thesis deals with the characteristics and changing laws under different calcining temperatures of waste slag. Fully chemical analysis technique, X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to characterize the crystalline phases and their changing laws and microstructures and so on.By testing the water absorption, porosity , bulk density, flexural strength, micro-hardness and wear rate of ceramic balls, the ideal prescriptions for raw materials were proposed. XRD and SEM techniques were used to determine the structure details including crystalline phases, compositions,and microstructures and so on. The effects of firing process on properties and microstructures of alumina ball have been studied. The results indicate that the major composition of aluminum waste slag is Al₂O₃ existed in form of γ-AlOOH, partly in crystalline and partly in amorphous solid state.They are completely transformed into stable α-Al₂O₃ at high temperatures, thus waste slag can replace commercial alumina to make alumina grinding ball as main raw material by high-temperature sintering.In order to keep the prescription stable and avoid crack of grinding balls,the waste slag must be pretreated. The optimal calcining temperature of the waste slag was 1300℃. The optimum proportion of raw materials is determined on the basis of BaO-MgO-SiO₂-Al₂O₃ phase diagram which consists of approximately 70wt% waste slag(pretreated), 20wt% clay, 5.5wt% barium carbonate and 3.5wt% talc powder. The the properties of the products made according to such prescription is comparable to that of commercial ones. Its water absorption is 0.032%,porosity is 0.105%,bulk density is 3.289 g/cm³,flexural strength is 136 MPa, micro-hardness is 8.25 GPa ,wear rate is 0.441‰/h. XRD and SEM results reveal that the major phases of grinding balls are spinel ,hyalophane , mullite and α-Al₂O₃ in hexagonal plate shape.As a consepuence,the body has relatively high dendities.