CHEMICALS & PHARMACEUTICALS


THE DRIVERS FOR A CIRCULAR ECONOMY


Florence Luyten, Account Manager at Indaver for precious metal recycling from liquids, explains how rising demand and technological advances are driving a circular economy for precious metals used as homogeneous catalysts


H


omogeneous catalysts lie at the heart of fine chemicals manufacturing, including pharmaceuticals and agrochemical. Examples include precious metal acetates, chlorides, nitrates, oxides or sulphates. Increases in scope and demand of these catalysts over the past two decades have led to unyielding demand for their component precious metals.


However, industrial mining is expensive, it is subject to resource depletion, and it has significant environmental impacts. As well as habitat destruction, soil erosion, land degradation, water and air pollution, the energy consumption associated with mining releases substantial carbon dioxide into the atmosphere. Fortunately, the precious metals used in homogeneous catalysts are ideal candidates for a circular economy [1]. They accelerate chemical processes without being consumed or changed, and that means that they can be recovered and recycled. The recovery process can be challenging, as it involves recovering low concentrations of precious metals from large volumes of liquids, but the high value and scarcity of precious metals make the process worthwhile. For example, we have demonstrated that palladium concentrations as low as 20 ppm (and as high as 6,000 ppm) are economic to recycle.


The past few years have seen a significant increase in the recycling of precious metals such as palladium (Pd), rhodium (Rh), platinum (Pt), ruthenium (Ru), iridium (Ir) and silver (Ag), which may be used as homogeneous catalysts. Indaver specialises in the recycling of precious metals from liquid streams. The Inda-MP facility in Antwerp, Belgium, recovers precious metals directly from the liquid phases resulting from processes based on homogeneous precious metal catalysts. Cost and environmental benefits are complemented by an infrastructure and procedures that are fully environmentally compliant.


Homogeneous catalysts used in industry


A recent study performed by Indaver in collaboration with KU Leuven, a well- known research university located in Leuven, Belgium, showed that Indaver’s recycling processes for precious metals resulted in carbon savings of up to 98%, compared with primary mining. Based on laboratory testing, the recovery method that offers the highest


Liquid phases originating from processes based on Homogeneous precious metal catalysts


Liquid streams delivered to Indaver


Organic and solvent streams


Aqueous Line 1


Precious metal and solvent used again


Line 2


Precious metal extracted


Solvent recovery


streams and those with sediment


efficiency at the most favourable cost is selected. Advanced techniques like precipitation, adsorption and thermal methods enable the recovery of precious metals from liquids streams in any compound or shape. • Precipitation: Conversion of soluble metal species into insoluble solid compounds that can be separated by filtration from the liquid stream.


• Adsorption: Selective recovery of metals from complex liquid phases by adsorption on to carbon materials, metal-organic frameworks, biopolymers or resins.


Precious metal used again


• Thermal methods: Methods such as thermal reduction play an important role in precious metals recycling. As shown in Figure 1 (left), the Antwerp site has two installations: Line 1 uses thermal methods to recover precious metals from organic and solvent streams, while Line 2 performs precipitation and adsorption to recover precious metals from aqueous streams and streams with sediment. This two-line approach allows flexibility in providing optimal processing for any individual stream. Waste streams are never mixed to avoid contamination – the work is done in a batch process with full traceability.


Figure 1 22


Liquid fraction safely treated, including management of any hazardous components


Treatment of liquid fraction Once the precious metal is recovered, the remaining liquid fraction needs to be treated. This includes liquids that may be hazardous, toxic, flammable or corrosive. It is important that any installations recovering precious metals can also deal with these liquid fractions appropriately.


PROCESS & CONTROL ENGINEERING | APRIL 2026


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