(1. 太原理工大學 化學化工學院，太原 030024;
2. 中南大學 冶金與環(huán)境學院，長沙 410083)
摘 要: 以沉金后液為原料，采用SO2為還原劑，研究在鹵素以及鹵素復合催化劑存在條件下還原沉金后液中的硒碲以及捕集貴金屬金鉑鈀的工藝。結果表明:在85 ℃、硫酸濃度167 g/L、SO2流量0.2 L/min的條件下，當Cl-催化劑濃度為1.1 mol/L、反應時間2 h，或當Br-催化劑濃度為0.5 mol/L、反應時間3 h，或當I-催化劑濃度為0.3 mol/L、反應時間2 h時，硒金鉑鈀還原率達到100%，碲還原率達到99.60%以上。采用鹵素復合催化劑，當NaCl與NaBr摩爾比為1:2時，有助于加快硒碲的還原，而且降低了催化劑的用量。SO2催化還原后產物中含碲74.56%、銅11.85%、硒7.38%，貴金屬金3.89%、鉑0.19%、鈀1.02%(質量分數);還原產物中碲以單質狀態(tài)存在，產物形貌為球狀體。熱力學分析表明:硫酸濃度為167 g/L時，Se(Ⅳ)主要以H2SeO3形式存在，Te(Ⅳ)主要以H3TeO3+形式存在;當溶液中有Cl-存在時，溶液中H3TeO3+在Cl-締合作用下逐漸轉變?yōu)門eCl62-，其電極電勢較H3TeO3+的正，促進碲的還原。
關鍵字: SO2;還原;鹵素離子;沉金后液;熱力學
（1. College of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan 030024, China;
2. School of Metallurgical and Environmental, Central South University, Changsha 410083, China）
Abstract:Selenium and tellurium were recovered and gold, platinum and palladium were captured from precipitated gold solution. SO2 was used as reducer, halogen ion and composited halogen ions were used as catalysts in the reaction. The experimental results show that the reduction rates of selenium, gold, platinum and palladium are 100% and the reduction rate of tellurium is more than 99.60% when Cl- concentration is 1.1 mol/L and reaction time is 2 h, or Br- concentration is 0.5 mol/L and reaction time is 3 h, or I- concentration is 0.3 mol/L, reaction time is 2 h. Under the condition of reaction temperature 85 ℃, H2SO4 concentration 167 g/L and SO2 flow rate 0.2 L/min. The reaction speed is faster than that of NaCl catalyst when the molar ratio of NaCl to NaBr in the composited catalysts is 1:2. The mass fractions of tellurium, copper, selenium, gold, platinum, palladium in the reduction product are 74.56%, 11.85%, 7.38%, 3.89%, 0.19%, 1.02% (mass fraction), respectively. Tellurium exists in the form of simple substance in the reduction product and the morphologies of the product are spheroid bodies. Thermodynamic analysis show that Se(Ⅳ) mainly exists in the form of H2SeO3, Te(Ⅳ) mainly exists in the form of H3TeO3+, H3TeO3+ gradually transforms into TeCl62- in association with Cl-. Cl- promots the reduction of Te(Ⅳ) because the electrode potential of TeCl62- is higher than H3TeO3+.
Key words: SO2; reduce; halogen ion; precipitated gold solution; thermodynamics
