Abstract Phosphorus extraction from phosphorus rock was conducted by carbothermal reduction with silica and coke. The effects of reaction temperature, reaction time, coke excess coefficient, molar ratio of silicon–calcium, and phosphorus rock particle size on the phosphorus reduction rate were investigated by the response surface methodology (RSM). The central composite design (CCD) with five factors and five levels was used to explore the effects of variables’ interactions on the phosphorus reduction rate. The results showed that there are significant interactions between reaction time and temperature; reaction temperature and molar ratio of silicon–calcium; reaction temperature and phosphorus rock particle size; coke excess coefficient and molar ratio of silicon–calcium; and coke excess coefficient and phosphorus rock particle size. The optimum conditions in the experimental range are reaction time 92 min, reaction temperature 1340°C, coke excess coefficient 1.27, molar ratio of silicon–calcium 1.28, and phosphorus rock particle size 75–106 µm, which were derived from the quadratic statistic model. Under these conditions, the phosphorus reduction rate can reach 96.88%, which is close to the model prediction value 99.40%. The optimized carbothermal reduction conditions of phosphorus rock by the RSM are helpful to reduce the energy cost of thermal phosphoric acid process.

中文翻译：

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响应面法优化中低品位磷岩碳热还原工艺

摘要 用二氧化硅和焦炭进行碳热还原从磷岩中提取磷。采用响应面法(RSM)研究了反应温度、反应时间、焦炭过量系数、硅钙摩尔比和磷岩粒径对磷还原率的影响。采用五因素五水平的中心复合设计(CCD)来探讨变量相互作用对磷减少率的影响。结果表明，反应时间与温度之间存在显着的交互作用；反应温度和硅钙摩尔比；反应温度和磷矿粒度；焦炭过剩系数和硅钙摩尔比；焦炭过剩系数和磷矿粒度。实验范围内的最佳条件为反应时间92 min，反应温度1340℃，焦炭过剩系数1.27，硅钙摩尔比1.28，磷岩粒径75-106 μm，由二次统计模型推导出. 在此条件下，磷还原率可达96.88%，接近模型预测值99.40%。RSM优化的磷矿碳热还原条件有助于降低热磷酸工艺的能源成本。磷减少率可达96.88%，接近模型预测值99.40%。RSM优化的磷矿碳热还原条件有助于降低热磷酸工艺的能源成本。磷减少率可达96.88%，接近模型预测值99.40%。RSM优化的磷矿碳热还原条件有助于降低热磷酸工艺的能源成本。