Abstract
Throughout human history, gold has been the most sought-after and well-known precious metal in the world. It is synonymous with wealth in the financial market and jewellery. However, its use has a wide range of applicability in biomedicine, electronic engineering and other industries. Primary gold resources are limited and have been significantly depleted in recent decades. To cover the current demand, it is necessary to process secondary sources containing gold such as heaps, tailings, lean ores or electrical waste. New and especially more efficient technological procedures are needed for the processing of these secondary sources. From an environmental point of view, a hydrometallurgical process is considered to be more appropriate than a pyrometallurgical process, in which very toxic fumes enter the air. This work investigates the leaching of gold from flotation wastes using thiourea. It is flotation waste that is the target group of materials that are a source of precious metals. An interesting gold content is present in our waste sample (Hodruša Hámre tailings pond), but its evaluation depends on the setting of suitable technological conditions. In this work, thiourea is used as an alternative leaching agent to toxic cyanide, which is banned in Slovakia and many countries around the world due to its high environmental risk. The results of the study are described with respect to the gold recovery under optimized thiourea leaching conditions.
Highlights
In Slovakia, too, there is a gradual tendency to balance the profit of precious metals in terms of input costs to the selling price of the product and to take into account the management costs of processing waste and subsequent remediation or revitalization of the environment burdened by the production process
We still have to solve the issue of processing secondary material such as flotation waste, electrical waste and less balance stocks, in which precious metals are found in lower concentrations
The sample surface was characterized by X-ray photoelectron spectroscopy (XPS) spectral analysis on a SPECS instrument with a PHOIBOS 100 SCD electron analyzer at a non - monochromatic X-ray source
Summary
The consumption of metals is increasing with the development and the massification of new technologies, which concerns a growing number of metals from the periodic table. These evolutions are increasing the pressure on the global supply chains, which in turn contributes to risks of scarcity for various metals. Current technologies for processing primary and secondary sources of precious metals offer a wide range of ecologically and economically profitable work processes. A foreign mining company exports gold-bearing concentrate outside Slovakia, it processes it by cyanide leaching. It is only a matter of time before the ban on the use of cyanides is gradually extended to all developed countries around the world. We offer a summary of basic and wellstudied methods in this area
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