Reduced environmental impacts for the precious metal refining industry
The ALS2 project improved and implemented an innovative, chemical-free separation technology called ‘AcidLess’ for refining gold and other precious metals. “We introduced automation to enhance the separation and recovery of gold, silver, platinum and iridium resources and other critical raw materials of key industrial importance,” states Enrico Cappellini, Commercial and Marketing Director for IKOI, an Italian SME providing technology to the global precious metal industry. The original AcidLess technology, developed by IKOI, separates gold from precious metal alloys using differential evaporation and condensation of metals under nearly vacuum conditions. According to Cappellini: “The raw materials are heated in an electrical induction crucible and then separated out using a special filter. This approach allows very fine control of the process parameters, which are managed via a digital interface.” Researchers pushed this technology further by modelling and developing an automatic system to pour molten metal after the distillation phase to effectively cast anodes for the subsequent electrorefining step. “By applying this approach, we can reduce the number of steps required to process the raw material and reduce the energy consumption of the whole procedure,” Cappellini explains.
A question of scale
ALS2 both upscaled and downscaled their technology to make it more accessible to a range of users and implemented an automated tilting system for pouring the molten metal directly after distillation. The team produced a prototype AcidLess separation plant with a 175 kg capacity and the tilting function. They also created a small 15 kg prototype that can be easily adopted by small refiners and jewellers. “Successfully scaling up of the technology and the tilting function are important advances, as they remove major obstacles to the adoption of AcidLess by major players in the industry,” comments Cappellini. “On the opposite side of the spectrum, the development of a small, simple and compact version of the plant posed a challenge in analysing and evaluating the target market and its needs.” Researchers selected the most suitable materials for components that must withstand high temperatures, vacuum conditions, an oxidising atmosphere and mechanical stresses due to the harsh operating environment. “We’ve also discovered other potential uses of the technology, to separate other metals, such as tin, lead and other impurities. These findings have great potential to bring new applications but require further study,” Cappellini notes.
Friendlier to the environment
ALS2 provided a better understanding about the industry and its key drivers, from a technological and a marketing viewpoint. This has resulted in greater adoption of the technology and the promotion of a circular supply chain. Precious metal refineries can immediately profit from adopting ALS2 technology by reducing operating costs and processing speed. Moreover, communities around these facilities can benefit from the reduced use, transport, handling, storing and disposal of the chemicals traditionally employed in refining. The entire industry can effectively begin to design a future less dependent upon chemicals and move towards a truly green way to process precious metals. “The technology can also be applied to waste electrical and electronic equipment recycling, even though we have only just begun to scratch the surface of its potential in this sector,” Cappellini concludes.
Keywords
ALS2, precious metals, refining, electrical induction crucible, circular supply chain, waste electrical and electronic equipment
