Key Laboratory of Solid Waste Treatment and Resource Recycle, Ministry of Education, Mianyang, 621010, China.
School of Material Science and Engineering, Chongqing Jiaotong University, Chongqing, 400074, China.
Environ Sci Pollut Res Int. 2022 Sep;29(44):67456-67465. doi: 10.1007/s11356-022-22737-y. Epub 2022 Sep 1.
The waste product phosphogypsum (PG) is produced in phosphoric acid production processes. Its storage requires large amounts of land resources and poses serious environmental risks. In this work, detailed experimental research was carried out to investigate the potential reuse of PG after calcination modification as a novel building material for cast-in-place concrete products. The calcination modification mechanism was studied, and the environmental risk assessment of modified PG was presented. The results showed that the calcination modification includes crystal phase transformation, removal of impurities, and modifying the pH value. The calcination was carried out at 280 °C for 5 h, where the resulting product was a pH value of 7.1, and the soluble fluorine and phosphorus removal rates reached up to 69.2% and 71.2%, respectively. These removal rates met the requirements of the China national standard Phosphogypsum (GB/T 23456-2018). To ensure the environmental safety, ecological risk assessment methods for determining the leaching toxicity of the modified PG were employed. The toxicity of Ba and P elements in the modified PG products was assessed, as well as the leaching toxicity concentrations of all particular heavy metals, which were found well below the limits set by the national standards. All the results presented strongly suggest that the 280 °C modified PG presented here has excellent application potential as a raw component in building materials.
磷石膏（PG）是在磷酸生产过程中产生的。它的储存需要大量的土地资源，并存在严重的环境风险。在这项工作中，我们进行了详细的实验研究，以探讨经过煅烧改性后的 PG 作为现浇混凝土制品新型建筑材料的潜在再利用。研究了煅烧改性的机理，并提出了改性 PG 的环境风险评估。结果表明，煅烧改性包括晶相转变、杂质去除和 pH 值调整。煅烧在 280°C 下进行 5 小时，得到的产物 pH 值为 7.1，可溶性氟和磷的去除率分别达到 69.2%和 71.2%。这些去除率符合中国国家标准《磷石膏》（GB/T 23456-2018）的要求。为了确保环境安全，采用了确定改性 PG 浸出毒性的生态风险评估方法。评估了改性 PG 产品中 Ba 和 P 元素的毒性，以及所有特定重金属的浸出毒性浓度，发现均远低于国家标准规定的限值。所有结果都表明，本文提出的 280°C 改性 PG 作为建筑材料的原材料具有优异的应用潜力。
