块状磷矿石在磷酸溶液中的溶出研究

Study of Dissolution of Gritty Phosphate Rock in Phosphoric Acid Solution

磷酸直接与磷矿石反应浸取是直接法生产浓磷酸的关键步骤。直接法生产浓磷酸可以充分利用反应热,与二水法工艺相比,可使用较大粒度、低品位的磷矿石,不需要浓缩,反应过程中需移出的反应热大幅减少,因此可降低能耗、节约成本。以P2O5质量分数为18.80%的磷矿石为原料、磷酸用量为理论量的2.0倍时,磷酸直接浸取磷矿石的最佳反应条件为:反应温度70℃,反应时间3 h,磷酸质量分数54%(以P2O5计,下同),磷矿石粒度0.90～2.80 mm;以P2O5质量分数为22.87%的中品位磷矿为原料时,磷酸直接浸取磷矿石的最佳反应条件为:反应温度90℃,反应时间2 h,磷酸质量分数45%,磷矿石粒度≤0.45 mm,磷酸用量为理论量的4.5倍。

Direct reaction of phosphoric acid with phosphate rock and leaching are the key steps m the production of concentrated phosphoric acid by the direct method, which fully utilizes the reaction heat, and compared to the dihydrate process, can use larger particle size, low-grade phosphate rock, without further concentration, and the reaction heat to be removed in reaction is reduced by a great margin, so that the energy consumption may be less, and the cost reduced. With phosphate rock of P2O5 mass fraction of 18.80% as the raw material and 2.0 times of the theoretical quantity of phosphoric acid, the optimal reaction conditions for the direct leaching of phosphate rock with phosphoric acid are： reaction temperature of 70 ℃, reaction time of 3 h, mass fraction of phosphoric acid of 54% （ based on P2O5, the same hereinafter）, phosphate rock particle size of 0, 90 -2.80 ram. With medium-grade phosphate rock of P205 mass fraction of 22.8% as the raw material, the optimal reaction conditions for the direct leaching of phosphate rock with phosphoric acid are： reaction temperature of 90 ℃, reaction time of 2 h, mass fraction of phosphoric acid of 45%, phosphate rock particle size ≤0. 45 mm, and consumption of phosphoric acid of 4.5 times the theoretical value.