MINING CHEMICALS
Designed to support metallurgists in optimising recovery in continuous leaching , Orica ’ s LeachIT simulation software allows customers to visualise and predict gold leaching outcomes based on a mine ’ s unique requirements
A state of flux
The application of new , innovative chemical formulations are helping miners lower their costs as well as reduce their environmental impact , Dan Gleeson reports
The COVID-19 pandemic has failed to push the mining sector ’ s environmentally focused chemical use agenda off course , with all reagents , depressants , extractants and collectors being heavily scrutinised for their risk to the environment as well as their potential effectiveness in the process plant .
This continues to be best displayed in the cyanide space , where manufacturers and users of the lixiviant are re-evaluating its place in the industry .
Two recent news items exemplify this better than most .
Cyanide conundrum
In March , the Chemours Company , a global chemistry company , announced the initiation of a strategic review to assess the potential sale of its Mining Solutions business , a part of the Chemours Chemical Solutions segment .
The process , intended to drive shareholder value and portfolio focus , could see one of the largest North America-based producers of solid sodium cyanide come off Chemours ’ books .
Ed Sparks , Chemours Titanium Technologies and Chemical Solutions President , said recent investments in production capability and infrastructure at the company ’ s Memphis plant – the largest solid sodium cyanide plant in the world – along with supply chain optimisation efforts to reduce costs , would enable Mining Solutions to “ maximise growth and margin expansion , further increasing the value of this highly successful business .”
He added : “ The Mining Solutions business remains committed to addressing the everchanging needs of the precious metals mining industry , throughout and following this strategic review .”
In the same month as Chemours came out with this review , Cyanco , a leading producer of sodium cyanide for precious metal extraction worldwide , announced it had formed a strategic partnership with Cycladex Ltd , the developer of a newly patented cyanide-free process to rapidly recover gold and silver .
The companies established a funded joint technology development program and a revenue sharing agreement on collaborative projects that , they said , would benefit both .
Through the partnership , Cyanco says it can expand its offering aimed at the safe and efficient recovery of precious metals from ore . Cycladex , in turn , benefits from Cyanco ’ s established infrastructure and customer base , enabling it to , the company says , grow its presence in the mining industry .
Cycladex uses a novel , patented chemical process to recover gold and silver that does not use cyanide , reduces operating and capital costs , reduces gold recovery time scales , uses around 50 % less water and helps gold miners avoid land contamination , it says .
It sees gold leached from the ore using a bromide-based lixiviant that forms a tetrabromoaurate complex with gold . A solution of corn starch derived cyclodextrin is added to the leachate and , upon addition of the cyclodextrin , the lock-and-key crystal structure forms spontaneously and precipitates . The gold
is then released from the crystalline precipitate at high temperature to yield solid gold metal , the company explained .
Developed by Nobel Prize winner , Sir Fraser Stoddart , Director of the Center for the Chemistry of Integrated Systems at Northwestern University , this process has been proven for mining operations too remote to receive sodium cyanide , or whose infrastructures or ore characteristics may require a different mineral extraction process , Cycladex said . This has seen the technology work on ores at more than 30 mines worldwide .
Recently , the company , together with BC Mining of Baja Mexico , completed its first demonstration unit which has the capacity to process 2-4 t / d of gold ore . And , together with Triple 7 Mining , a gold company in Arizona , USA , it completed scale-up gold ore leaching trials running more than 20 batches at pilot scale .
Cyanco President and CEO , Michael Lefenfeld , said : “ Cyanco is continually evaluating new technologies with the potential to increase mineral yields for our customers . Each mine is different , with a range of ore characteristics , processing variables and unique environmental factors .
“ Through partnering with Cycladex , we believe we will be able to serve more mining customers – both large and small – by addressing a broader spectrum of mining needs , while continuing to focus on improving process efficiency and lowering operating costs .”
Roger Pettman , Executive Chairman of Cycladex , added : “ I am delighted to have entered into this partnership with Cyanco . Their outstanding reputation in the industry , technical expertise and global distribution network will allow us to expand our technology commercialisation efforts and help us realise our full growth potential .”
He added : “ We see many opportunities where the Cycladex technology fits nicely in a product portfolio alongside sodium cyanide .”
Switzerland-based Cyanoguard AG is all too aware of the changing patterns of precious metal producers when it comes to the use of cyanide . Indeed , it is capitalising on this trend .
The company has come up with a novel way of ensuring more accurate dosing of cyanide for cyanidation with a process that is now established with 18 clients across the globe .
It has devised a reliable , user friendly and intelligent real-time cyanide monitoring and optimisation solution that minimises toxic reagent usage and greenhouse gas emissions ,
MAY 2021 | International Mining 51