Itronics reveals new zinc leaching process

United States – US environmental group Itronics says it has ‘successfully tested’ a process for recovering zinc powder from brass mill flue dust.

The ZinLix process first leaches zinc oxide from the dust to create a zinc-enriched liquid, then uses an ‘electrowinning’ technique to produce a metallic powder. Itronics says this product or solid zinc metal could be sold into established markets, but also foresees a seasonal use in its existing chelated liquid zinc micronutrient fertilisers. Chelation is a particular way in which ions and molecules bind metal ions.

Eliminating waste

Itronics claims the new process is ‘zero discharge’ and uses 40% less electrical energy than conventional zinc refining. ‘Our innovative zinc recycling technology is expected to eliminate the zinc-bearing waste completely by converting all components to saleable goods,’ notes Itronics president Dr John Whitney.

The company estimates that more than 300 000 tonnes of secondary brass and bronze smelter zinc-bearing flue dusts per year is generated in the USA. Ultimately, it hopes to combine the new process with its existing FeLix technologies to recycle zinc-bearing flue dust from steel mini-mills. 

Timing is everything

The technology to solubilise zinc oxide from flue dust is already proven at a commercial scale and has been in use by Itronics for more than 10 years. The company says ZinLix works in a similar way to its existing silver-bearing photo-liquid recycling process.

Metal market analysts have predicted that zinc prices will rise substantially over the next three years owing to mine closures and delays in opening new mines. ‘The zinc market is tightening, and yet there is a huge amount of raw material available. The timing for our process is excellent,’ Whitney concludes.