Utilizing phosphate mine tailings to produce ceramisite

There are a large volume of phosphate tailings is produced in China each year. If the tailings are inappropriately disposed of, it may cause serious social problem. This paper presents a study to use phosphate mine tailings to make ceramisite materials, which can be used as building material. In the process, the phosphate tailings were mixed with soft interlayer and black shale materials. The effects of mass ratio among phosphate mine tailings, soft interlayer content and black shale and calcination parameters, such as preheating temperature, preheating time, sintering temperature and sintering time, on the properties of the ceramisite were investigated through single factor experimental testing. Based on the results of experimental tests, the calcination process was optimized. The single factor experimental study shows that the phosphorus content, water absorption rate and particle strength exhibit different correlations under the influence of the material ratio and calcination process. Further optimization tests were carried out and the results demonstrate the significance of influence factors following order: sintering temperature > preheating temperature > sintering time > preheating time. The calcination parameters were also obtained through optimization tests. Preheating temperature and time are 350 °C and 9.6 min respectively, and sintering temperature and time are 943 °C and 60 min respectively. Under those optimizing process, the available phosphorus content was determined to be 9.17%.