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JSDEWES_d7.0312
JSDEWES_d7.0312.pdf
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DOCUMENT SUMMARY:

Silver in E-Waste

Industrial Dependence

  • The Electrical and Electronic Equipment (EEE) sector uses about 30 % of global silver output — roughly 6 000 tonnes per year.
  • Silver is critical for circuit conductivity and soldering in PCBs, smartphones, TVs, and computers.

Concentration in Components

  • In waste printed-circuit boards (WPCBs), silver averages ~0.1 % (≈1 000 g/t) but ranges widely (0–380 g/t) depending on device type and age.
  • Silver (and gold) are mostly concentrated in the electronic components, not in the fiberglass base plates.
  • In the Croatian sample study:
    • New-generation cell-phones contained ~320 g Ag/t, together with very high gold (~1 070 g/t) and copper (~428 kg/t).
    • Other devices (computers, TVs) held ~220–330 g Ag/t, far above typical ore grades (0.5 – 5 g/t).

Granular Distribution

  • No strong silver trend by grain size, but it was slightly richer in smaller shredded fractions (< 0.5 mm).
  • Gold tended to concentrate in fine grains; copper and aluminum dominated coarse ones.

Economic and Environmental Significance

  • WPCBs contain Ag, Au, Cu at levels several times higher than in natural ores—making them “urban mines.”
  • Recovering these metals saves energy compared to primary mining and reduces toxicity if done properly.

Where the Silver and E-Waste End Up

Global Flows

  • Roughly 70 % of the world’s electronic waste (including silver-bearing PCBs) ends up in China, much of it illegally traded or informally recycled.
  • Only part of this stream enters formal recovery systems; informal workshops often burn or acid-leach boards, releasing toxic by-products and losing up to 30 % of metals, including silver.

Processing and Recovery

  • Recycling routes include:
    • Pyrometallurgical smelting (metal recovery but high emissions).
    • Hydrometallurgical leaching/refining (aqua regia, cyanide, or greener reagents).
    • Mechanical separation (shredding and gravity/magnetic sorting).
  • In Croatia’s example, PCBs were manually separated for copper/aluminum recovery, then exported or sent for further treatment abroad—typical of small-market nations.

Environmental Fate

  • Improper disposal (open burning or landfilling) causes silver, lead, tin, and brominated-resin leaching into soil and water.
  • Even in regulated systems, non-metal fractions (plastics, glass, resin) are often discarded or down-cycled (e.g., used as filler in construction materials).
  • Newer electronics use more silver, copper, and aluminum, but less lead and tin due to RoHS restrictions.
  • Smartphones are now the richest single E-waste source of precious metals.
  • Despite improved recycling laws, illegal or low-tech recovery remains dominant, meaning a large share of silver ultimately dissipates—lost to slag, ash, or uncontrolled dumps in Asia and Africa.

Modern electronics concentrate silver at ore-grade-plus levels, yet most of it is still lost in global E-waste trade loops, primarily exported to informal recycling hubs in China and other developing regions, where inefficient recovery and environmental leakage disperse this strategic metal into the biosphere.