Comprehensive Utilization of Phosphogypsum and Its Initial Utilization

In a recent interview, the reporter learned that the national standard of “building gypsum” is being amended to define phosphogypsum as a “product” for the first time, which means that phosphogypsum, which has long been considered as “residue residue” will get its name. Industry insiders reminded that companies should pay full attention to the new definition of phosphogypsum and make preparations as soon as possible. The revised national standard will be officially introduced and will create conditions for the comprehensive utilization of phosphogypsum.
Increasing environmental pressure In recent years, a series of national industrial policies have gradually tended to environmental protection. The increase in external pressure has made the phosphate fertilizer treatment problem in the phosphate fertilizer industry particularly problematic.
In the first half of 2006, the former State Environmental Protection Administration proposed the concept of phosphogypsum slag as hazardous waste. If this is the case, the existing phosphorous-phosphorus slag yard of the phosphate and compound fertilizer enterprises will not meet the requirements. At present, more than 100 million tons of phosphogypsum residue that will be stored will need to be disposed of again. It will take a lot of money to rebuild the slag yard again. Phosphate compound fertilizer companies added new products. Although this issue has caused widespread controversy, it has given a warning to the phosphate fertilizer industry in China: Phosphogypsum treatment and utilization should be accelerated.
Phosphogypsum has long been considered as a kind of waste residue. What is different now is that the national standard of “construction gypsum” is being revised, both in terms of “definition and terminology” and in “raw material composition of building gypsum”. Phosphogypsum is defined as "products" rather than "residues," and is referred to as one of the basic raw materials for building gypsum. This being the case, phosphate and compound fertilizer companies should establish the awareness that “phosphogypsum is a product” and manage it in the same way as other products. It is necessary to formulate the product standards for phosphogypsum in combination with relevant requirements, transport, storage, stacking, delivery, and storage yards. The management standards are strictly enforced.
According to industry sources, the revision of the National Standard for Building Plaster will, on the one hand, expand the scope of use of phosphogypsum and, on the other hand, create conditions for the comprehensive utilization of phosphogypsum from standards and specifications.
The new technology is ready to emerge The management and utilization of phosphogypsum is a worldwide problem. As the world's largest producer of phosphate fertilizers, China ranks first in the world in the production of by-product phosphorous gypsum slag. The reporter learned from an interview with Xi'an University of Architecture and Technology that the university cooperated with Guizhou Yifu Group Co., Ltd. (formerly Guizhou Hongfu) to carry out research and cooperation in the project, and used the high-solid-to-gas ratio suspension technology to rapidly decompose phosphogypsum to achieve phosphogypsum resources. Efficient use. This cross-cutting joint effort of the chemical and construction industry will produce new technologies for the use of phosphogypsum.
Chen Yanxin, head of scientific research at the Institute of Powder Science and Technology at Xi’an University of Architecture and Technology, told reporters that at present, China has not yet formed a mature technology that can comprehensively utilize phosphogypsum on a large scale. In the application of phosphogypsum, a large part of the phosphogypsum is used instead of natural gypsum to make architectural gypsum, and then processed into a variety of gypsum building materials products, but there are waterproof technology problems, product sales radius is also limited. Therefore, this is not the fundamental way to solve the use of phosphogypsum resources.
Chen Yanxin said that many years ago Xi'an University of Architecture and Technology began to study the use of phosphogypsum decomposition technology. They changed the existing process of accumulation of solid-gas heat transfer, and independently innovated the high-solid-state suspension technology than the rapid calcination technology to decompose phosphogypsum. Through high-temperature calcination at 1100°C, dehydration, and decomposition, phosphogypsum is decomposed into SO2 and CaO, the decomposition efficiency of SO2 is significantly increased, the production of by-product CaS is reduced, SO2 reprocessing production is a sulfuric acid product, and the utilization of waste resources is realized.
According to reports, Guizhou Yifu Group and Xi’an University of Architecture and Technology have started the pilot project of the decomposition of phosphogypsum by the high-solid-to-gas ratio of suspended solids, and the phosphogypsum treatment scale is 400 kg/h. After the test is successful, the phosphorus will be built at the Yongfu Group. Gypsum uses industrial demonstration devices.
Comprehensive utilization of progressive phosphogypsum Phosphogypsum is solid waste discharged during the production of wet-process phosphoric acid, and produces about 4-5 tons of phosphogypsum per ton of phosphoric acid produced. China's phosphorus chemical industry emits about 50 million tons of phosphogypsum per year, accounting for more than 70% of the industrial by-products of gypsum, and it grows at a rate of 15% per year. At present, the cumulative stock of phosphogypsum in the country exceeds 100 million tons. For a long time, phosphate and compound fertilizer companies mainly use the heap method, and the comprehensive utilization rate is only about 10%. This not only occupies a large amount of land, but also causes environmental pollution, which is a major problem that hampers the healthy development of the phosphate industry. For this reason, the China Phosphate Fertilizer Industry Association proposed that during the “11th Five-Year Plan” period, the annual treatment capacity of phosphogypsum should exceed 10 million tons, and the comprehensive utilization rate should be increased to 20% by 2010.
At present, many domestic phosphate and compound fertilizer companies pay more attention to the comprehensive utilization of phosphogypsum and have achieved certain results. The Shandong Lubei Group, the country’s major scientific and technological research project—gypsum sulfuric acid co-production cement technology test, has built the world’s largest phosphogypsum-based sulfuric acid plant with an annual output of 300,000 tons of ammonium phosphate, 400,000 tons of sulfuric acid and 600,000 tons of cement. Cogeneration of cement industry equipment consumes phosphogypsum from the company and its neighboring companies, achieving balanced production and sales of phosphogypsum; Lubei Group, Guizhou Fufu, and Guizhou Kaifeng use phosphate phosphogypsum to produce cement retarders, gypsum bricks, and mine mined District fills, etc., were selected by the National Development and Reform Commission as the pilot unit for the development of circular economy in the country; Ningxia Chemical Fertilizer Company of Luxi Chemical Group used the phosphogypsum flash burn technology to produce building gypsum powder with an annual output of 200,000 tons; Anhui Tonghua Group adopted various The calcining device produced building gypsum, cement retarder, etc.; Qinhuangdao Huayu Company and Jiangxi Guihua respectively built 20 million square meters/year gypsum board project. In addition, phosphorus compound fertilizer companies such as Shandong Hongri Akon, Aobao Chemicals, Guizhou Xiyang Group, Shaanxi Huashan Chemicals, and Chongqing Fuling Chemicals all performed well in the comprehensive utilization of phosphogypsum.

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