Abstract:

The agitation tank and Keltics static mixer were used to remove arsenic (As) from industrial phosphoric acid by using phosphorus pentasulfide (P₂S₅). The single factor experiments, orthogonal experiment and response suface methodology were conducted to acquire the optimal process conditions. The results showed that the removal efficiencies of both of the two reactors were higher than 98.8% and the content of As were less than 0.5 mg·kg^-1 in the purified phosphoric acid, which met the national standard of China GB 1886.15-2015 for food grade phosphoric acid. As the agitation tank was the reactor, the optimum process conditions were that the actual dosage of dearsenifying agent was 4 times of the theoretical dosage, reaction temperature was 65℃, reaction time was 70 min and the stirring speed was 300 r·min^-1. As the Keltics static mixer was the reactor, the optimum process conditions were that the actual dosage of dearsenifying agent was 4 times of the theoretical dosage and the phosphoric acid flow was 0.66 m³·s^-1. Under this condition, the disposal phosphoric flow was increased greatly, and the reaction time was only 2.4 s and the amount of phosphoric acid treated per unit of time is 372 times that of the stirred reactor. As Keltics static mixer is used to remove arsenic (As) from industrial phosphoric acid, there are many advantages, such as the shorter technological process, the simpler construction, the continuant operation, etc., which is hopefully to realize the process intensification of dearsenifying As from phosphoric.

摘要：

以五硫化二磷脱砷剂分别开展了搅拌混合及SK静态混合脱除工业磷酸中砷（As）的研究。利用单因素实验、正交实验和响应曲面实验设计，得到了最佳反应条件。结果表明：两种反应器最佳的脱砷剂用量均为理论用量的4倍，脱砷率大于99.8%，净化后的产品砷浓度小于0.5 mg·kg⁻¹，满足国家标准GB 1886.15—2015规定的食品级磷酸指标。搅拌反应器脱砷过程最佳反应温度65 ℃，反应时间70 min，搅拌速度300 r·min⁻¹；以SK静态混合器进行磷酸脱砷，最佳磷酸流速为0.66 m·s⁻¹，反应时间2.4 s，单位时间内处理的磷酸量是搅拌反应器的372倍。用SK静态混合器进行磷酸脱砷，具有工艺流程短、结构简单紧凑、可连续操作等优点，可以实现工业磷酸脱砷的过程强化。