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Phosphogypsum (PG) is a solid waste product generated during wet-process phosphoric acid production. Various impurities considerably reduce the purity, whiteness, and application range of PG. This article analyzes the physical properties of PG in detail and systematically examines the content and distribution of impurities. Based on the obtained re...
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... Indirect carbonation of waste gypsum consists of two main stages, involving the leaching of Ca 2+ from waste gypsum using leaching agents (acid, alkali, and salt), and reaction between CO 2 and Ca 2+ . Due to the impurities can be removed before carbonation, indirect carbonation can produce high-purity CaCO 3 (Chen et al., 2020b, c;Rahmani et al., 2016;Zhang and Fan, 2022c). As to indirect carbonation, the selection of Contreras et al. (2015) extractant is very important, which influences the carbonation efficiency, the purity of carbonation products and the cost. ...
The development of phosphogypsum (PG) recycling industry plays an important role in promoting the environmentally friendly transition of the phosphorus chemical industry, worldwide. China is the leading producer of phosphate and PG in the world, as the development of PG recycling industry in China has already generated very promising outcomes. Over 80% of China's total PG production in contributed collectively by four provinces, including Sichuan, Hubei, Guizhou, and Yunnan. By conducting an in-depth investigation to 18 representative companies involved in PG recycling allocated in these four provinces, the purpose of this study is acquired a comprehensive insight into the status quo of the development of PG recycling industry in China and its prevalent challenges. The results indicate that, first, recycled PG can be used in various applications, which predominantly encompassing in cement retarder, construction materials, engineering application, polymer materials, underground back filling, ecological restoration, sulfur acid, fertilizers, soil amendment, crafts, etc. Second, the key drivers behind the development of PG recycling industry include types of companies, technological innovation, products and markets, industrial policies, and geographical location. Third, the obstacles hindering the development of PG recycling industry include: a scarcity of innovative PG recycling companies; an absence of comprehensive technical evaluation standards and high-value technological breakthroughs; challenges in promoting PG-based products in the market; insufficient support from industrial policies; and the lack of geographical advantages contributing to sluggish industrial progress in specific regions. Fourth, the recommended corresponding solutions encompass: facilitating the transformation and upgrading of phosphorus chemical companies and promoting the coordinated development of PG recycling companies; instituting a technical evaluation standardized system and promoting high-value technologies; broadening the market channels and establishing a reproducible and scalable PG recycling industrial development model; accelerating the enhancement of industrial policies; and developing plans suitable for regional PG recycling industry based on local conditions.
The storage of phosphogypsum could bring huge burden to the environment, while the traditional method of washing and purifying phosphogypsum produced a large amount of waste water and colossal energy consumption. The novel colloidal-mechanical method as a new treatment technology of purifying phosphogypsum was benefit for the large-scale comprehensive utilization of phosphogypsum, but its purification effect and influencing factors needed to be further studied. Surfactants like Span-80, TX-100 and Tween-80 were one of major factors for colloidal-mechanical purification method about whiteness improvement and impurities removal of phosphogypsum. It created colloidal-mechanical microenvironments during the purification process of phosphogypsum, and helped to realize the best removal effects and purification technology of phosphogypsum. After characterization, it showed that the whiteness of phosphogypsum increased under the action of micelle and mechanical force, and the removal effects of soluble phosphorus and fluorine impurities were noticeable. The whiteness value of purified PAS could reach 51.9, which was 57.8% higher than natural PG. The phosphorus content in the slurry solution of PAS was 274.649 ppm, which was 208% higher than PG. The fluorine content in PAS was 0.289 wt%, which was 24.3% lower than PG. The purification effect of phosphogypsum was the best through the micro-environment created by Span-80 and mechanical force. This study provided a green design direction for the critical purification and its further utilization of phosphogypsum. This work provided a clear idea for solving the current purification dilemma of phosphogypsum with an outstanding application prospect.
