Extraction of Cr(Ⅵ) from chromite ore processing residue via hydrothermal-assisted phase transformation

作     者：Xiaofeng Mo Jin Zhou Le Lin Zuqi Zhong Shaohua Yang Xueming Liu Zhenqing Shi Dongye Zhao Zhang Lin Xiaofeng Mo;Jin Zhou;Le Lin;Zuqi Zhong;Shaohua Yang;Xueming Liu;Zhenqing Shi;Dongye Zhao;Zhang Lin

作者机构：The Key Laboratory of Pollution Control and Ecosystem Restoration in Industry Clusters(Ministry of Education)School of Environment and EnergySouth China University of TechnologyGuangzhou 510006China Sino-Singapore International Joint Research InstituteSino-Singapore Guangzhou Knowledge CityGuangzhou 510006China Environmental Engineering ProgramDepartment of Civil EngineeringAuburn UniversityAuburn AL 36849United States 

出 版 物：《Chinese Chemical Letters》 (中国化学快报（英文版）)

年 卷 期：2020年第31卷第7期

页      面：1956-1960页

核心收录：

学科分类：083002[工学-环境工程] 0830[工学-环境科学与工程（可授工学、理学、农学学位）] 07[理学] 08[工学] 070302[理学-分析化学] 0703[理学-化学] 070301[理学-无机化学] 

基　　金：the National Natural Science Foundation of China(No.21836002) the Young Innovative Talents Project in Higher Education of Guangdong(No.2018KQNCX002) Guangdong Innovative and Entrepreneurial Research Team Program(No.2016ZT06N569) the Fundamental Research Funds for the Central Universities(No.D2192000) the Shaoguan Special Fund for Soil Pollution Prevention and Control(No.2017sgtyfz103) the Youth Talent Promotion Project of Guangzhou Science and Technology Association(No.X20200301029)。 

主　　题：Chromite ore processing residue Hexavalent chromium extraction Hydrothermal mineralization Phase transformation 

摘      要：The effective extracting Cr(Ⅵ) from chromite ore processing residue(COPR) is the key to achieve COPR detoxification and recovery.We developed an effective method to extract Cr(Ⅵ) from COPR via controlling the phase transformation of Cr(Ⅵ)-containing minerals.Characteristic analysis showed that Cr(Ⅵ) was mainly incorporated in the hydrocalumite(NaCa4Al2O6(SO4/CrO4)1.5-15H2O) in COPR,which was a layered-double hydroxide(LDH) with multilayer structure.In the hydrothermal treatment experiments,the Na2CO3 solution showed significant extraction effect of Cr(Ⅵ) and detoxification effect of COPR.After treatment,95% of Cr(Ⅵ) was removed and the Cr(Ⅵ) concentration in the leachate was decreased to 1.6 mg/L by the toxicity characteristic leaching procedure(TCLP),within the regulatory limit disposal standard(HJ/T 301-2007,3 mg/L).Further study revealed that,during the treatment,hydrocalumite transformed into calcite(CaCO3) under the effect of mineralizer,therefore,the layered structure collapsed and the incorporated Cr(Ⅵ) was released to the supernatant.Meanwhile,the Cr(Ⅵ)desorbed from calcite with the calcite particles grew into large size with smooth surface.Stir-flow experiment revealed that the amount of chromium released from CORP to the environment was significantly reduced after treatment,and it is safer for landfill disposal.This work will provide an instructive guidance for the detoxification and recovery of COPR.