Page 29 - Bullion World Volume 4 Issue 2 February 2024

Bullion World | Volume 4 | Issue 2 | February 2024

metal loss, purity issues, and high operational costs investment and operational complexities of refining.
hinder widespread use. While smelting processes excel in handling large material
volumes, determining the precise composition of varied
Metal Extraction Options for PCBs lots processed in a smelting line is challenging, especially
Smelting + Electrorefining if materials lack homogeneity. This complexity extends to
Smelting, currently a prevalent method treating up to accurate pre-sampling.
70% of PCBs, involves incinerating crushed PCBs in
furnaces, creating a low-concentration PGM alloy with Disadvantages of outsource processing:
impurities. Base metals removal is necessary before • Lower value realized
processing PGMs. Integrated smelters mostly recover • High shipping costs
copper, as iron and aluminum concentrate in the • Prolonged payment terms
produced slag. PCBs' ceramics and glass contribute • Locked working capital
to higher slag formation, causing a significant loss of • High carbon footprint
precious and base metals. Apart from high energy
consumption, smelting poses a risk of dioxin and other On-Site Processing (Smelting)
hazardous toxins release, addressed by advanced In certain instances, recyclers establish their own
pollution abatement processes. smelting facilities, resembling third-party smelters
but typically on a smaller scale. While they encounter
For additional metal processing, electrorefining is comparable environmental and operational challenges,
essential. In this process, anodes are cast from molten they effectively extract the inherent value of metals and
alloy, leading to the production of pure copper cathodes avoid shipping costs.
in electro-refining cells. During electrolysis, copper
dissolves into the solution, plates as a pure copper Downsides of on-site processing:
cathode, while noble metals like gold and PGMs fall • Smelting permits are hard to obtain and highly
to the bottom, generating anode slime every 15-20 capital intensive
days. Less noble metals dissolve at the anode, causing • Requires additional processing steps
impurity build-up and electrolyte contamination, • Higher working capital in the precious metals
necessitating bleeding to maintain copper cathode • High carbon footprint
quality.
Digestion + Electrowinning
Outsource Processing (Smelting) E-waste recyclers often opt for digestion coupled
Some E-Waste recyclers opt to delegate additional feed with various purification technologies. This method
processing to third-party facilities to sidestep the capital involves caustic or acid leaching followed by

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