(1. 太原理工大学 化学化工学院，太原 030024;
2. 中南大学 冶金与环境学院，长沙 410083)
摘 要: 以沉金后液为原料，采用SO2为还原剂，研究在卤素以及卤素复合催化剂存在条件下还原沉金后液中的硒碲以及捕集贵金属金铂钯的工艺。结果表明:在85 ℃、硫酸浓度167 g/L、SO2流量0.2 L/min的条件下，当Cl-催化剂浓度为1.1 mol/L、反应时间2 h，或当Br-催化剂浓度为0.5 mol/L、反应时间3 h，或当I-催化剂浓度为0.3 mol/L、反应时间2 h时，硒金铂钯还原率达到100%，碲还原率达到99.60%以上。采用卤素复合催化剂，当NaCl与NaBr摩尔比为1:2时，有助于加快硒碲的还原，而且降低了催化剂的用量。SO2催化还原后产物中含碲74.56%、铜11.85%、硒7.38%，贵金属金3.89%、铂0.19%、钯1.02%(质量分数);还原产物中碲以单质状态存在，产物形貌为球状体。热力学分析表明:硫酸浓度为167 g/L时，Se(Ⅳ)主要以H2SeO3形式存在，Te(Ⅳ)主要以H3TeO3+形式存在;当溶液中有Cl-存在时，溶液中H3TeO3+在Cl-缔合作用下逐渐转变为TeCl62-，其电极电势较H3TeO3+的正，促进碲的还原。
关键字: SO2;还原;卤素离子;沉金后液;热力学
（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
