CINVESTAV Saltillo, Avenida Industria Metalúrgica 1062, Parque Industrial Saltillo-Ramos Arizpe, Ramos Arizpe, Coahuila 25900, Mexico.
CINVESTAV Saltillo, Avenida Industria Metalúrgica 1062, Parque Industrial Saltillo-Ramos Arizpe, Ramos Arizpe, Coahuila 25900, Mexico.
J Hazard Mater. 2016 Nov 5;317:440-448. doi: 10.1016/j.jhazmat.2016.05.085. Epub 2016 May 31.
The recovery of silver from hazardous jarosite residues was studied employing thiourea as leaching agent at acid pH and 90°C. The stability of the thiourea in synthetic solutions was evaluated in the presence of some cations that can be present in this leaching system: cupric and ferric ions as oxidant species, and zinc, lead and iron as divalent ions. Two silver leaching methods were studied: the simultaneous jarosite decomposition-silver leaching, and the jarosite decomposition followed by the silver leaching. The study with synthetic solutions demonstrated that cupric and ferric ions have a negative effect on thiourea stability due to their oxidant properties. The effect of cupric ions is more significant than the effect of ferric ions; other studied cations (Fe(2+), Zn(2+), Pb(2+)) had no effect on the stability of thiourea. When the decomposition of jarosite and the silver leaching are carried out simultaneously, 70% of the silver can be recovered. When the acid decomposition was performed at pH 0.5 followed by the leaching step at pH 1, total silver recovery increased up to 90%. The zinc is completely dissolved with any of these processes while the lead is practically insoluble with these systems producing a lead-rich residue.
研究了在酸性 pH 值和 90°C 下，使用硫脲作为浸出剂从有害铁矾渣中回收银。在存在一些可能存在于该浸出系统中的阳离子的情况下，评估了硫脲在合成溶液中的稳定性：作为氧化剂的铜离子和铁离子，以及作为二价离子的锌、铅和铁。研究了两种银浸出方法：铁矾分解-银浸出的同时进行，以及铁矾分解后进行银浸出。在合成溶液中的研究表明，由于铜离子和铁离子的氧化性，它们对硫脲稳定性有负面影响。铜离子的影响比铁离子的影响更显著；研究的其他阳离子（Fe(2+)、Zn(2+)、Pb(2+)）对硫脲的稳定性没有影响。当同时进行铁矾分解和银浸出时，可以回收 70%的银。当在 pH 值 0.5 下进行酸分解，然后在 pH 值 1 下进行浸出步骤时，总银回收率增加到 90%。这些过程中锌完全溶解，而铅几乎不溶解，产生富含铅的残渣。
