盐酸法制备磷酸一铵和磷酸二铵

Preparations of monoammonium phosphate and diammonium phosphate by hydrochloric acid

用盐酸浸取含15.84%P2O5的浏阳贫磷矿制取粗磷酸,以三聚氰胺为磷酸沉淀剂从中分离磷酸,研究单因素实验条件下反应温度、搅拌时间、反应物摩尔比以及三聚氰胺加料方式对磷酸沉淀率的影响,并考察沉淀物中夹带的盐分氯化钙的洗涤情况。研究结果表明:在25～30℃、三聚氰胺与磷酸摩尔比为2:1、三聚氰胺分成两份进行两步沉淀、各搅拌60min为三聚氰胺沉淀磷酸的最佳条件,在此条件下磷酸沉淀率大于99%;在磷酸三聚氰胺沉淀中夹带的氯化钙在固液质量比1:5、温度40℃和搅拌60min下用水反复洗涤3次后可被完全去除;再将净化后的磷酸三聚氰胺与氨水反应,制得了符合GB10205—2001标准的磷酸一铵和磷酸二铵产品。该工艺路线可行,反应条件温和,中间媒质三聚氰胺可循环使用,以氯化钙副产品替代了磷石膏的产出,减缓了硫资源的消耗,避免了硫酸根对三聚氰胺沉淀的影响,适合于贫磷矿资源的开发。

The crude phosphoric acid was prepared by the Liuyang poor phosphate ore containing 15.84% P2O5 and hydrochloric acid, and the phosphoric acid was separated using trimeric cyanamide as phosphoric acid precipitant. The effects of reaction temperature, stirring time, the mole ratio of reactants and the washing manner of precipitant on the precipitation rate of phosphorus acid and the wash rate of calcium chloride were emphatically researched. The results indicate that the precipitation rate of phosphoric acid is larger than 99% under the conditions of 25-30℃, the mole ratio of trimeric cyanamide to phosphoric acid 2：1, two-step precipitation by trimeric cyanamide divided into two portions and separately stirring 60 min. The salt component calcium chloride entrained in the precipitation of trimeric cyanamide phosphate can be fully removed in the mass ratio of solid to liquid 1：5, at temperature 40℃, stirring time 60 min and repeatedly washing three times with water. Then through the purified trimeric cyanamide phosphate reacting with ammonia water, the products of monoammonium phosphate and diammonium phosphate which conform to GB 10205-2001 standard are fabricated. The preparation conditions of the process are gentle, the middle medium trimeric cyanamide can be recycled, the consumption of sulfur resource is slowed down by calcium chloride by-product substituted for the output of phosphogypsum, the influence of sulfate radical on trimeric cyanamide precipitation is avoided, and it is suitable for the development of low-grade phosphate ore resource.