Precious metals & the path to a circular economy
Florence Luyten, account manager for precious metal recycling from liquids at Indaver, explains how advances in recycling technologies are enabling a circular economy for precious metals
Precious metals such as palladium, rhodium, platinum, ruthenium, iridium and silver are crucial to various industries due to their unique properties, including excellent electrical conductivity, corrosion resistance, durability and catalytic activity. They are also used for homogeneous catalysts, which have increased in scope and demand over the past two decades.
Homogeneous catalysts now lie at the heart of many industrial processes producing APIs, agrochemical AIs and fine chemicals. Examples include precious metal acetates, chlorides, nitrates, oxides or sulphates. By lowering energy barriers, they drive chemical processes in the speciality chemicals, agrochemicals, electronics, pharmaceuticals and other global industries.
Conventional sourcing
Ever since man first extracted gold from the earth about 6,000 years ago, precious metals have been mined from natural mineral deposits. These deposits of precious metals, in various forms, are the result of cosmic and geological processes, making them a unique and valuable resource but also a finite one. 1 Significant depletions are inevitable if we continue mining at current rates.
Furthermore, industrial mining has significant environmental impacts: habitat destruction, soil erosion, land degradation, water contamination and air pollution, and substantial carbon dioxide emissions from the
Figure 1- Circular economy for precious metals used in industrial homogeneous catalysts
Liquid streams delivered to Indaver
Organic and solvent streams Line 1 Line 2
Precious metal & solvent used again
energy consumed. The ecological effects of mining can persist for decades after operations cease, with derelict land permanently altering the landscape and large areas unusable for agriculture or habitation.
Candidates for a circular economy
Most precious metals are highly durable. They can be used as homogeneous catalysts precisely because they accelerate chemical processes without being consumed or
Precious metal extracted
Solvent recovery
Liquid fraction safely treated, including management of any hazardous components
Liquid phases originating from processes based on homogeneous precious metal catalysts
Aqueous streams & those with sediment
Precious metal used again
changed, and that means that they can be recovered and recycled.
Although the recovery process can be challenging, as it involves recovering low concentrations of precious metals from large volumes of liquids, the high value and scarcity of precious metals make the process worthwhile. In fact, precious metals are ideal candidates for a circular economy. 2
The past few years have seen a significant increase in precious metal recycling, contributing to sustainability
64 SPECIALITY CHEMICALS MAGAZINE ESTABLISHED 1981