Phosphogypsum Direct Decomposition Method Developed Successfully

China's phosphogypsum utilization of resources to achieve a breakthrough. Nanchang Fanjie Technology Co., Ltd. released a news release on August 7, said that the company developed a direct decomposition method for the separation of phosphogypsum technology can be obtained 99%, whiteness of nearly 100% of high-purity gypsum, the impurity slag obtained by further refining Rare earth salts can also be obtained later.

It is understood that phosphogypsum is actually a gypsum containing impurities, and impurities contain a large amount of rare earth metals. If the impurities can be completely separated from the gypsum, not only high-purity and high-whiteness high-purity gypsum can be obtained, but also the impurity slag can be used as a raw material for refining rare earth metals after being enriched. Therefore, the complete separation of impurities and gypsum is the key to the full utilization of phosphogypsum.

After the success of the research in the laboratory, the researchers of Nanchang Fanjie used this idea to build a set of phosphogypsum separation industrial test equipment. The obtained high-purity white gypsum product was tested by the Jiangxi Provincial Analysis and Test Center, with a content of 99.11%. The impurity slag contained more than 20 kinds of metals, most of which were rare earth metals, and the utilization rate of phosphogypsum was nearly 100%, completely solving the phosphogypsum resources. Use this worldwide problem.

According to Zhang Fan, general manager of Nanchang Fanci, the direct decomposition method of phosphogypsum is a method of dissolving calcium sulfate at room temperature. First, the insoluble black residue is separated and washed by filtration; thereafter, the filtrate conditions are changed so that the dissolved calcium sulfate crystallizes. Precipitate, filtered, washed and dried to obtain high purity calcium sulfate. The resulting high-purity gypsum can be further converted and decomposed to produce sulfuric acid and produce superfine calcium carbonate as a by-product. Black slag contains a large amount of rare earth metals, which can be used as a raw material for refining rare earth metals after re-enrichment.

Zhang Fan said that the direct decomposition method is characterized by a smooth and easy process, no consumption of acid, alkali, no high temperature, and no emissions of pollutants, can be regarded as a full green chemical process. Not only does the process itself have significant economic benefits, the company can also avoid the cost of land acquisition for phosphogypsum storage in each year. Taking an annual output of 100,000 tons of high-purity gypsum as an example, the required investment is about 20 million yuan, the production cost per ton of high-purity gypsum is 209 yuan, and the annual net profit of 100,000 tons of high-purity gypsum is as high as 139.1 million yuan. The income of rare earth metals has not yet been included and the economic benefits are obvious.

According to Zhang Zhixin, a chemical technology expert who has long been engaged in the study of the waste chemical waste of the *Phosphorus chemical industry, high-purity gypsum has a wide range of uses. Its high whiteness and purity can be used in rubber, plastics, coatings, paper, medicine, food and other industries. The manufacture of advanced building materials and decorative materials, high-quality plaster whiskers, etc., can fully replace the highest quality natural gypsum.

At present, China has added more than 70 million tons of phosphogypsum annually. Phosphogypsum can be used as a retarder for cement, or for building blocks or bricks. However, it is difficult to fundamentally solve the problem of phosphogypsum accumulation. The full use of resources is the ultimate outlet for phosphogypsum.