Preparation And Properties Of Ion - Type Rare Earth Tailings

Ion-type rare earth ore is a precious rare earth resource in China. However, there were producing a lot of rare earth ore tailings because of its backward mining technology in the early stage. These tailings are stockpiling in mining area or surrounding. It not only a waste of resources, but also occupy large tracts of land, which is easily lead to soil erosion, landslides and other geological disasters. Therefore, how to harmless and reduce the rare earth tailings is an important problem in front of us.According to the characters of these rare earth tailing(hereinafter referred to as “rare earth tailings”) which contain with high content of clay, using it to prepare ceramic to achieve the goal to change the tails into resource, so as to achieve the harmless and reduction. Firstly, the basic properties of rare earth tailings were researched. It was found that the tailing mainly composed of clay minerals, such as quartz, kaolinite, which is completely meet the requirements for preparation of ceramsite. On this basis, the sintering method for preparing ceramic was studied. The experimental results show that the furnace natural cooling can make the ceramsite has a pore better structure. In a certain range, the increase of aluminum silicon ratio can effectively improve the compressive strength of the ceramsite. Moreover, with the increasing of sintering temperature and sintering time in a certain the range, the pore structure and compressive strength performance of the ceramsite would be promoted. The optimum conditions of sintering ceramsite preparation were determined by condition experiments. Under the optimum sintering condition, ceramsite with water absorption rate of 34.19%, apparent porosity of 55.51%,compressive strength of 3.62 Mpa and volume density of 1.23g/cm3 could be obtained. Secondly,the non-sintering method for preparing ceramic process was studied. In the research, the effect of calcium excitation non-sintering method and alkali activated non-sintering method on ceramsite preparation effect was compared. The experimental results showed that used calcium excitation method for preparation of the non-sintering ceramsite has better performance. The ceramsite prepared by calcium excitation non-sintering method is more suitable for wastewater treatment.The optimum conditions of sintering ceramsite preparation were determined by condition experiments. Under the optimum non-sintering condition, ceramsite with water absorption rate of30.28%, apparent porosity of 49.96%, compressive strength of 3.17 Mpa and volume density of1.65g/cm3 could be obtained.The microstructure of the ceramsites prepared by sintering method and non-sintering method were analyzed by SEM. The results shows that the internal structure of sintering ceramsite is uniform, closely, and average pore size distribution was throughout. Its uniform spilehole constitute the porous structure of the skeleton of the ceramsite. The internal porous structure of non-sintering ceramsite is very rich, the main form of which is irregular connected large hole.Moreover, the internal of the non-sintering ceramsite is uneven, which shows it has rich pore and large surface area. Therefore, the ceramsite prepared by sintering method and non-sintering method are all suit for the characteristics of ceramsites using for wastewater treatment.The characteristics of sintering ceramsite and non-sintering ceramsite were detected. The results show that, the water absorption rate, apparent porosity, compressive strength and volume density of the ceramisite prepared by sintering method and non-sintering method can meet the national requirements. Moreover, leaching toxicity of the ceramsite are all meet the relevent requirements. Sintering ceramsite and non-sintering ceramsite are showing a certain effect ontreat ammonia-nitrogen wastewater. In the practical application, the further modification of the ceramsite is also necessary to improve its wastewater treatment capacity.