Discover the silver bullet: More profitable and sustainable mining through chemistry
Sustainable solutions to make metal extraction less complex
Whether mines recover precious metals such as gold, silver and platinum or base metals like zinc, copper and lead, they all face similar challenges. As the world’s most valuable ores have already been mined, they are now left to process ores with lower metal content, making it essential to extract secondary metals as byproducts to maximize revenue. As an expression in the mining world says: ‘The quality of today’s feed is yesterday’s tailings’ (tailings being the unwanted leftover minerals). On top of that, mines face growing pressure to reduce their fresh water usage for processing.
Even after more than 100 years of use, flotation is still the most cost-effective and widely used mineral recovery technology for most ore bodies. In this process, flotation reagents are used to separate desired minerals from non-value minerals, and air is added to create bubbles that transport particles to the surface so they can be collected. Flotation conditions are controlled for optimum performance; collectors attach to the surface of valuable metal particles to make them hydrophobic, enabling their separation. The most commonly used collectors in the mining industry today present certain limitations. Solvay offers an alternative that can boost revenues by improving the efficiency of the flotation process, while at the same time reducing the quantities of reagent needed.
Better extraction for more revenue
AEROPHINE® is the only commercial mineral processing collector based on phosphinate chemistry (dithiophosphinate). It requires a complex manufacturing process, and Solvay is one of the only companies in the world that has mastered the production of collectors based on phosphorus derivatives.
AEROPHINE® flotation reagent is stable, safe and easy to handle, while reducing transportation hassles as it isn’t subject to dangerous goods regulations. Above all, because it is more selective in its reactions with mineral particles, it improves separation efficiency. This results in the production of higher-grade concentrates that sell for a higher price to smelters (who reduce metal sulfides to pure metals).
AEROPHINE® has proven so successful in the processing of polymetallic ores that it’s anecdotally known as a silver bullet within the flotation industry.
Case studies have demonstrated recovery improvements of 2-5% for base metals, 1-2% for gold and 3-5% for silver, with strong statistical certainty. In this era of high metal prices, those additional percentage points translate into substantial financial gains for mining operators and are the surest way of improving Net Smelter Return (NSR), or the proceeds of metal sales once transport and treatment have been deducted.
Mine operators using AEROPHINE® typically see a return on investment in the range of 300-1000% (partly due to the fact that up to 50% lower dosages are needed). “AEROPHINE® is currently used in over 100 mines in 30 countries,” says Eammon Guitard, Global Marketing Manager for Mineral Processing at Solvay’s Technology Solutions business unit. “And it’s proven so successful in the processing of polymetallic ores that it’s anecdotally known as a silver bullet within the flotation industry.”
To each ore its chemistry
In mining, no two ore bodies are alike. Even two mines on either side of the same mountain can have ores with very different characteristics. And within these complex circumstances, reagents can help maintain selectivity against ‘penalties’: elements such as arsenic and bismuth that are naturally present in the ore, which tend to be otherwise recovered and contaminate the metal concentrates. This is also important in order to optimize returns; concentrates that contain too high a percentage of penalties will get rejected.
Therefore, tailoring flotation chemistry is crucial in order to adapt as precisely as possible to local conditions (even the quality of the water used has a big impact on the process), and mine operators have to constantly make adjustments to ensure their plants remain profitable.
“Reagent chemistry is a key lever for metallurgists to maximize NSR,” explains Tarun Bhambhani, Principal Scientist at Solvay, “so much so that using the right collector chemistry can boost revenues even if the price of one value metal goes down.”
That’s why AEROPHINE® is also available in blends and customized formulations so it can better meet the needs of each operation – for example, plants that extract copper and gold from the same site.
Performance and sustainability
Lastly, using phosphinate chemistry improves the health and sustainability profile of mines. Since significantly smaller quantities of reagent are necessary operating personnel are exposed to fewer chemicals. What’s more, thanks to the unique selectivity of AEROPHINE®, dosages of highly toxic depressants such as cyanide (used to increase the efficiency of the flotation process) are reduced, and sometimes eliminated altogether. In contrast, alternative collectors tend to require higher doses, and are more dangerous and difficult to handle.
In a world where the quality of mineral reserves continues to decline while demand for metals increases, the mining industry must improve the efficiency of its processes, and that means opting for the highest-performing chemical solutions. In line with this trend, Solvay has recently expanded its manufacturing plant in Welland, Ontario, doubling the production capacity of AEROPHINE® to accommodate future demand.