The results from the analysis, the reaction time increases the material, the rate of defluorination phosphate ore significantly improved. When the residence time of the material in the high temperature furnace is not less than 45 min, the defluoridation rate can reach over 98%, and the fluorine content and phosphorus content of the product can meet the requirements of the superior product index. However, the reaction residence time is too long, and the defluorination rate and phosphorus conversion rate of phosphate rock no longer increase, but have a tendency to decrease. Unprolonged reaction time is also not conducive to energy saving. By the above results, the present process recipe and process conditions for the control of heavy metals of low grade phosphate rock feed tricalcium phosphate for regions feasible. The phosphorus content of the products produced by phosphate mines in Yunnan, Guizhou and Sichuan can reach the superior product standard of Q/YHY 01-2003 “Feed Grade Tricalcium Phosphateâ€, and the phosphorus content of products produced by Hubei Phosphate Mine reaches Q/YHY 01—2003 Feed grade tricalcium phosphate is the first-class standard for enterprise standards. Guizhou, Hubei phosphate rock sintering defluoridation reaction temperature is 1 300 ° C higher than Yunnan mine 50 ° C, Guizhou phosphate rock defluoridation agent dosage is 4% higher than Yunnan phosphate rock. The adaptability test of the process formula proves that the developed defluorination agent has wide adaptability to different phosphate mines. Compared with Korean products, it can reach the quality indicators of similar foreign products. 4 Conclusions The low-concentration metal phosphate rock in Yunnan Province was used as raw material, and the dephosphorization of tricalcium phosphate was tested according to the phosphate rock-phosphoric acid-defluorination agent (AMP) process. The optimum process formula and control conditions were adapted to Yunnan, Guizhou and Hubei. Minerals of low heavy metals in Sichuan and other places. Pipe Processing Production Line Pipe Cutting Production Line,Fully Automatic Pipe Cutting Machine,Copper Pipe Cutting Machine,Round Bar Pipe Cutting Machine Zhangjiagang heshun machinery manufacturer co.,ltd. , https://www.hsformer.com
3.4.5 Preferential process conditions test Through the above process conditions test, determine the best process control conditions: 1 material CaO / P 2 O 5 molar ratio is 2.50 ~ 2.60; 2 defluorination agent (AMP) is added phosphorus 4% to 8% of the amount of mineral powder; 3 sintering temperature is 1 250 ~ 1 300 ° C; 4 sintering time is 45 ~ 60min.
According to the preferential process control conditions determined above, the phosphate rock mines in Yunnan, Sichuan and Guizhou were tested for preferential process conditions, and the results were compared with Korean products (see Table 8). 
3.4.6 Analysis of the material structure of the test product There are two forms of tricalcium phosphate, α-type and β-form. When pure tricalcium phosphate is at 180 °C, β-Ca 3 (PO 4 ) 2 will be converted into activity. Good α-Ca 3 (PO 4 ) 2 , but α-Ca 3 (PO 4 ) 2 is slowly converted to β-Ca 3 (PO 4 ) 2 during cooling. According to the research of FT Nelson in the United States, when impurities such as MgO, Al 2 O 3 and Fe 2 O 3 are present, these impurities will prevent the β-form from being converted into α-type, so that β-Ca 3 (PO 4 ) 2 remains. stable. When phosphoric acid is added to the phosphate rock, the resulting tricalcium phosphate is basically β-type. The results of this evaluation test also prove this statement.
We conducted X-ray diffraction phase qualitative analysis on the tricalcium phosphate products produced in Yunnan, Guizhou, Sichuan, and Hubei phosphate mines and the Korean tricalcium phosphate products. The results of all dephosphorized tricalcium phosphate products produced by phosphate rock The main material structure is β-Ca 3 (PO 4 ) 2 . Due to the difference in impurity composition of different phosphates, the structure of the substances formed by impurities is also different.