Experimental Study On Sintered Ceramic From Phosphate Tailings And Its Utilization Of Resource

Phosphate tailing is the residue waste after the floating concentrate of phosphorite. Plenty of phosphate tailing is stacked due to the low content of phosphorus pentoxide in phosphate tailing, many impurities and no economic value of produced phosphatic fertilizer or phosphoric acid. However, there are still multiple useful elements contained in phosphate tailing, how to effectively take advantage of the useful elements in phosphate tailing is one of the hot subjects of comprehensive utilization of resources. At present, the methods of using phosphate tailing mainly include re-concentration of secondary resource, building materials and soil conditioner and so on in domestic. The pottery is fired with phosphate tailing, soft layer and black shale as the raw materials in this paper. Determine the firing technology of pottery through single factor experiment, then optimize the technology by adopting response surface methodology, make experimental study on resource utilization for pottery product finally, which provides new way for the comprehensive utilization of phosphate tailing, soft layer and black shale, experimental bases for the utilization of phosphorous in phosphate tailing at the same time. Its main works and results are as following:(1) Make research and analysis on the chemical composition and phase of phosphate tailing, soft layer, black shale with XRF and XRD. P2O5 existed in the raw material is found in the results, and it mainly exists in the form of gydroxyapatite [Ca5(PO4)3(OH)], fluorapatite [Ca5(PO4)3F] and a lot of it are stacked in the tailings pond and not be used fully, so that the resources is wasted.(2) The pottery is fired with the phosphate tailing as the main ingredient and soft layer and black shale as the auxiliary material; make analysis on the effect of raw material ratio and firing technology for the content of available phosphorus, total phosphorus content, one-hour water absorption, particle strength and stacking density through the single factor experiment. The optimum conditions for firing pottery determined finally are: phosphate tailing: soft layer: black shale: 81%; 9%; 10%; 400? of preheating temperature, 10 min of preheating time, 900? of sintering temperature and 50 min of sintering temperature. By this time, the available phosphorus content is 8.32%, total phosphorus content is 14.86%, 1h water absorption is 13.82%, stacking density is 922.43kg/m3 and particle strength is 270.92 N in pottery product of phosphate tailing.(3) Make optimal experiment on ratio of raw material and firing technology by adopting response surface method(RSM) for getting higher available phosphorus and better performance of pottery product. Make variance analysis on response surface model of response value(available phosphorus, 1h of water absorption) respectively and make significant analysis on response surface with P value, experiment value and predicated value; the phosphate tailing content and 1h water absorption obtained by model predication are in accordance with results of this confirmatory experiment through the comprehensive analysis of graphic of response surface finally. The experiment conditions obtained by optimizing are: phosphate tailing: soft layer: black shale: 82%:9%:9%;350? of preheating temperature, 6 min of preheating time, 883? of sintering temperature and 60 min of sintering temperature; By this time, the available phosphorus content is 9.17%, total phosphorus content is 14.23%, 1h water absorption is 14.95%, particle strength is 270.92 N and stacking density is 922.43kg/m3 in pottery product of phosphate tailing. Compared with single factor experiment, available phosphorus increases by 11.9%, 1h water absorption increases by 8.2% and stacking density increases by 6%.(4) The findings obtained by resource utilization on pottery product of phosphate tailing are as follows: there is material basis of 9.17% available phosphorus contained in pottery product of phosphate tailing can improve soil fertilizer efficiency; there is phosphate mineral crystal founded in the product by analyzing pottery product with XRD, which can neutralize acid soil PH; the indexes of five heavy metal contents of As, Hg, Cd, Pb and Cr and PH meet the GB8172-87 Agriculture Utilization for Urban Wastes, which can be used to make study of agricultural resources. The finding that can be obtained by making pakchoi pot experiment with pottery product of phosphate tailing is: with the increasing of application amount of pottery, the capacity of drought resistance of pot that applied with pottery decreases and water demand increases; compared with treating group that is not applied with pottery, plant length, fresh weight of single plant, output of the treatment group applied with potter are higher than the treating group not applied with pottery; as the mass fraction of pottery is 60%, the output of pakchoi will be the highest and the largest rate of growth is 77.31%, which indicates that pottery of phosphate tailing has great application and development prospect in the aspect of agricultural resource treatment.