Solís-Marcial O J, Nájera-Bastida A, Talavera-López Alfonso, Serrano Rosales Benito, Hernandez Jose A, Zarate-Gutiérrez R
Instituto Politécnico Nacional-UPIIZ, Ingeniería Metalúrgica, Blvd. del Bote 202, Cerro del Gato, Zacatecas 98160, Mexico.
Unidad Académica de Ciencias Químicas, Universidad de Zacatecas, Campus UAZ Siglo XXI, Zacatecas 98160, Mexico.
Materials (Basel). 2022 Nov 2;15(21):7704. doi: 10.3390/ma15217704.
Galena is the most important mineral for lead production, as it is the main source of lead in the world. Currently, the concentrates of this mineral are mainly treated using pyrometallurgical methods, creating several environmental problems, such as the generation of toxic and greenhouse gases. In addition, these processes involve high energy consumption, which limits their applicability. Hydrometallurgical routes are proposed as alternative processes for obtaining some metals such as silver, copper, gold, etc. The drawback of these processes is that the minerals tend to be passive in aqueous media. To mitigate this issue, researchers have used extreme conditions of pressure and temperature (6 atm. and 155 °C) or the use of very corrosive conditions. In this sense, the use of complexing agents that dissolve the metals of interest has been proposed. Citrate ion is one of the most promising complexing agents for galena leaching, obtaining high percentages of dissolution in relatively short times. Unfortunately, there has not been enough investigation about the concentration optimization of the complexing in the pH range from 5 to 9. In this sense, thermodynamic diagrams, such as the Pourbaix diagrams, are very useful for this purpose. Therefore, in this work, the effects of pH and temperature on the leaching of galena in citrate ion solutions are studied thermodynamically and experimentally. The experimental work was carried out with pure galena samples with a particle size of +149 - 74 µm (-100 + 200 mesh). The results show that higher recoveries were obtained working at a pH of 8 and at temperatures of 30 and 40 °C. The thermodynamic and experimental data demonstrated that the existence of an optimal concentration of citrate ion, due the extraction of lead from galena, has a greater reaction rate at a relatively low initial concentration of 0.3 M. This is due the formation of the complex lead citrate 1 (Pb(cit)-).
方铅矿是铅生产中最重要的矿物，因为它是世界上铅的主要来源。目前，这种矿物的精矿主要采用火法冶金方法处理，会产生一些环境问题，如产生有毒气体和温室气体。此外，这些工艺能耗高，限制了它们的适用性。湿法冶金路线被提议作为获取银、铜、金等一些金属的替代工艺。这些工艺的缺点是矿物在水介质中往往呈惰性。为缓解这一问题，研究人员采用了极端的压力和温度条件（6个大气压和155℃）或使用腐蚀性很强的条件。从这个意义上说，有人提议使用能溶解目标金属的络合剂。柠檬酸根离子是方铅矿浸出最有前景的络合剂之一，能在相对较短的时间内获得高溶解率。不幸的是，对于pH值在5至9范围内络合剂浓度的优化研究还不够。从这个意义上说，诸如Pourbaix图之类的热力学图在此目的上非常有用。因此，在这项工作中，从热力学和实验角度研究了pH值和温度对方铅矿在柠檬酸根离子溶液中浸出的影响。实验工作使用了粒度为+149 - 74微米（-100 + 200目）的纯方铅矿样品。结果表明，在pH值为8以及温度为30℃和40℃时获得了更高的回收率。热力学和实验数据表明，由于从方铅矿中提取铅，存在一个柠檬酸根离子的最佳浓度，在相对较低的初始浓度0.3M时反应速率更高。这是由于形成了络合物柠檬酸铅1（Pb(cit)-）。
