Ma Xu, Yuan Zidan, Zhang Guoqing, Zhang Jiaxi, Wang Xin, Wang Shaofeng, Jia Yongfeng
Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China.
University of Chinese Academy of Sciences, Beijing 100049, China.
ACS Omega. 2020 May 28;5(22):12979-12988. doi: 10.1021/acsomega.0c00849. eCollection 2020 Jun 9.
Arsenic-calcium residue (ACR) is one of the major hazardous solid wastes produced by the metallurgical industry that poses a serious threat to the environment. However, a suitable method for the effective treatment of ACR is still lacking. In this study, an alternative treatment method for ACRs via the immobilization of As as scorodite was proposed with the use of two types of ACRs (ACR directly collected from a Pb refinery and ACR precipitated from waste sulfuric acid in the lab). The treatment of ACR included preparing the As-enriched solution via HSO dissolution-neutralization of ACR at pH < 2, As(III) was oxidized by HO, and As(V) was immobilized as scorodite. The results showed that gypsum produced from ACR in the dissolution-neutralization process contained 68 mg/kg of As, far below the Chinese national standard for hazardous solid wastes (<0.1 wt %, GB5085.62007). The gypsum produced from ACR contained 5400 mg/kg of As due to the presence of original high-As gypsum (1.6 wt %) in ACR. These results showed that the preliminary removal of SO from waste sulfuric acid by lime neutralization-precipitation at pH ∼ 2 could produce pure-phase gypsum by avoiding the HAsO isomorphic substitution for SO . The scorodite produced from both ACRs displayed good As stability at pH 4.95 (0.9 and 0.5 mg/L) via the toxicity characteristic leaching procedure (TCLP) method and at pH 3-7 (0.4-3.0 mg/L) via a 15 day short-term stability test.
砷钙渣（ACR）是冶金行业产生的主要危险固体废物之一，对环境构成严重威胁。然而，目前仍缺乏一种有效的ACR处理方法。本研究提出了一种通过将砷固定为臭葱石来处理ACR的替代方法，使用了两种类型的ACR（直接从铅冶炼厂收集的ACR和实验室中从废硫酸中沉淀的ACR）。ACR的处理包括在pH<2的条件下通过HSO溶解-中和ACR制备富砷溶液，用HO氧化As(III)，并将As(V)固定为臭葱石。结果表明，ACR在溶解-中和过程中产生的石膏含砷量为68 mg/kg，远低于中国危险固体废物国家标准（<0.1 wt%，GB5085.62007）。由于ACR中存在原始高砷石膏（1.6 wt%），ACR产生的石膏含砷量为5400 mg/kg。这些结果表明，通过在pH~2的条件下用石灰中和沉淀法初步去除废硫酸中的SO，可以避免HAsO对SO的同晶替代，从而产生纯相石膏。通过毒性特征浸出程序（TCLP）方法，两种ACR产生的臭葱石在pH 4.95（0.9和0.5 mg/L）时显示出良好的砷稳定性，通过15天短期稳定性试验，在pH 3-7（0.4-3.0 mg/L）时也显示出良好的砷稳定性。
