响应面法优化废印刷线路板的金萃取条件

摘要

The sponge gold was obtained by using“breaking—removing low priced metal with sulfuric acid oxidation method—leaching gold—extracting gold with methyl isobutyl ketone (MIBK)—stripping gold”process. The statistical methods were used to analyze the impact of different factors on the extraction of Au (Ⅲ) using MIBK as extractant. The factorial designs with five factors and two levels were firstly used to evaluate the relative effects that might affect the extraction of gold from the waste printed circuit board with MIBK. The results show that the factors including the phase ratio of organic and aqueous, the reaction time and the temperature, have significant impacts on the extraction rate of gold. The phase ratio and reaction time have positive impacts on the gold extraction, while temperature has negative impact. Based on this, Box­Behnken central composite design combining with response surface methodology (RSM) was employed to optimize the most important affecting factors of the extraction rate. The optimum conditions for the extraction are the organic and aqueous phase ratio of 0.34, reaction time of 12.4 min and temperature of 28℃, which are calculated from an established quadratic equation of one variable regression model. Under the optimized conditions, the gold extraction rate can reach as high as 96.1%. At last, the organic phase is stripped with solution of oxalic acid (5%) to get sponge gold.%　　对回收废线路板采用“破碎—氧化硫酸法分离贱金属—浸出金—甲基异丁酮溶剂萃取提金—反萃析金”工艺获得海绵金，采用统计学方法及Minitab15软件对甲基异丁酮(MIBK)萃取线路板中金的影响因素进行探讨和分析。针对萃金过程，首先采用析因设计法进行5因素2水平的部分析因试验设计，对MIBK萃金的影响因素进行筛选，发现相比、反应时间和反应温度对金萃取率有显著影响，而且相比时间的影响具有正效应，温度具有负效应；利用Box­Behnken中心组合设计及响应面分析对影响金萃取率的显著因素做进一步的优化，建立多元二次回归方程拟合模型，得到最佳的萃取条件：相比0.34，反应时间12.4 min，反应温度28℃，在此条件下金的萃取率可高达96.1%，对MIBK萃金后的有机相用5%的草酸溶液进行反萃还原，得到海绵金。