title: [EXAFS study on the stripping mechanism in N263/alkaline cyanide gold solution/sulfuric thiourea system].
abstract: Quaternary ammonium salt has strong affinity with gold in cyanide solutions, but it is not readily stripped. Stripping with acidic thiourea solutions and air sparging shows promise. There are some reports on the process of thiourea stripping, but little about its mechanism. In this paper, the stripping mechanism of N263/sulphuric thiourea/alkaline cyanide gold solution is studied by EXAFS. According to the experiments, sulphuric acid, thiourea and gold-thiourea complex can be extracted by N263 as a neutral molecule, and the stripping process can be described as following: (1) Sulphuric acid and thiourea are extracted by N263; (2) In organic phase, gold-cyanide complex is converted to gold-thiourea complex, which exists as Au[SC(NH2)2]2HSO4, and CN- forms HCN with acid at the same time; (3) HCN is removed by air sparging, and Au[SC(NH2)2]2HSO4 is distributed between organic phase and liquor phase, most of which transfers to liquor phase and is stripped.
authors.affiliation: Institute of Nuclear Energy and Technology, Tsinghua University, Beijing 102201, China.
authors.forename: Hong-ping
authors.initials: HP
authors.lastname: Tang
authors.forename: Ming-de
authors.initials: MD
authors.lastname: Yang
authors.forename: Pei-jiong
authors.initials: PJ
authors.lastname: He
authors.forename: Tian-dou
authors.initials: TD
authors.lastname: Hu
authors.forename: Jing
authors.initials: J
authors.lastname: Zhang
authors.forename: Ya-ning
authors.initials: YN
authors.lastname: Xie
mesh_terms: D000588:Amines; D003485:Cyanates / Q000737:chemistry; D003486:Cyanides / Q000737:chemistry; D004563:Electrochemistry; D004784:Environmental Monitoring; D006046:Gold / Q000737:chemistry / Q000302:isolation & purification*; D006863:Hydrogen-Ion Concentration; D053768:Metal Nanoparticles / Q000737:chemistry; D036103:Nanotechnology; D019999:Pharmaceutical Solutions; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*; D011934:Reagent Strips / Q000737:chemistry*; D012996:Solutions / Q000737:chemistry; D013464:Sulfuric Acids / Q000737:chemistry; D013890:Thiourea / Q000737:chemistry*
chemical_list: D000588:Amines; D003485:Cyanates; D003486:Cyanides; D019999:Pharmaceutical Solutions; D000644:Quaternary Ammonium Compounds; D011934:Reagent Strips; D012996:Solutions; D013464:Sulfuric Acids; C043041:gold cyanide; D006046:Gold; D013890:Thiourea; C033158:sulfuric acid