Recycling Technology

Efficient Technology for Precious, Rare and Refractory Metals Extraction from Secondary Raw Materials

Today, precious and rare metals represent not only the source of wealth but, as well, the important material for engineering, electronics and science. Currently, the quantity of secondary raw materials containing precious and rare metals appears to be comparable with natural sources. The existing technologies for processing of raw materials aim at the extraction of precious and rare metals from large quantities of homogeneous primary raw materials having a low content of the metals. Methods and equipment used for this are very expensive and cannot be used for processing of small amounts of raw materials. Processing of secondary raw materials on the existing large-scale industrial plants results in big losses of precious and rare metals, since the peculiarities of such materials are not taken into account. Besides, the cost of processing of secondary raw materials by standard industrial methods often exceeds the value of extracted metals. The offered technology, which comprises a low-cost automated refining system, is mainly directed towards extraction of precious, rare and refractory metals, such as gold, metals of platinum group, silver, tungsten, molybdenum and rhenium from secondary row materials usually containing up to 5% (wt/wt) of metals. Such materials are originated from utilization, recycling, repairing and modernization of several generations of electronic and communication equipment and computers. They comprise: (i) scrap from rolling, cladding and punching, e.g., printing nips, contact springs, and clinchers, (ii) two- and multi-layer parts covered by a thin layer of precious metals, (iii) parts conjoined with plastics, ceramics, glass and other components of so-called electronic scrap, e.g., scrap of electronic parts, such as resistors, capacitors, switches and relays, devices for microwave technology, reading devices, converters, chips, hybrid microelectronic circuits, connectors, transistors, printed circuits, parts of commutation systems, etc. The technology is based on the method of chemical leaching that transfers all the metal compounds into the liquid phase enabling the sequential highly-efficient selective extraction of precious and rare metals with minimum losses, regardless of raw material composition and structure. The technology is directed towards total elimination of emission of hazardous substances into environment by using the closed-cycle technological scheme. The fulfillment of the given project will allow construction of low-cost production units for economically sound extraction of precious, rare and refractory metals from secondary raw materials.