Cyanidation is the most common method of leaching gold from ore, but not all leach reactors are made equal. On large scale gold recovery operations, even the smallest of changes can have a major impact on overall performance. While a difference of 98 to 99% target mineral recovery may not seem substantial, it could mean the difference of millions of dollars in revenue, potentially creating a make-or-break situation for some companies. Sepro Leach Reactors allow over 99% of the gold to be recovered through a simple, fully automated process. 

Here’s how it works. 

Gold Recovery With A Sepro Leach Reactor

Recovering gold with a Sepro Leach Reactor can be a complicated process. Here’s a quick summary of how it works. 

Concentrate, typically from a Falcon SB Gravity Concentrator, is collected in a concentrate hopper. From the hopper, it is pumped into the leach reactor, where all the necessary reagents are added for the cyanidation process. The mixture is then agitated to ensure that all the particles are properly exposed to the reagents.

sepro process flow diagram

After agitation, the pregnant gold solution is drained from the tank, leaving the solid gangue behind. The solution is washed, briefly agitated again, and rinsed. From here, the tailings are discharged and the pregnant solution is ready for electrowinning. 

How Sepro Improves The Efficiency And Effectiveness Of Gold Recovery

We’ve engineered the Sepro Leach Reactor to address the most common issues with the cyanidation process while improving gold recovery standards. 

Improving Leach Completion

Leach completion is the percentage of gold that is leached by the end of the designated leach time. Every percent can make significant impacts on revenues, so it’s vital to keep leach completion as high as possible. Standard leaching systems can deliver around 97 to 98% overall gold recovery, which is quite a high standard. The Sepro Leach Reactor has been proven to deliver upward of 99% gold recovery

Reducing Leach Times

Industry-standard intensive leach times are around 24 hours for a full cycle. We wanted to improve upon this for our clients, while also maintaining our superior recovery rates. We accomplish this by adding more energy during the leaching process through off-bottom agitation. This drives a quicker reaction, allowing us to speed up the reaction kinetics, which-in-turn delivers faster leach times.

In the chart above we see a comparison of our Sepro Leach Reactor versus rolling bottle leach tests. These tests were performed at one of our most recent installations at Atlantic Gold’s Moose River Project. We can see clearly that the Sepro Leach Reactor recovers a higher percentage of gold in a shorter amount of time versus the benchmark laboratory cyanidation process on which other intensive leach technologies are based. 

The agitation also enables off-bottom suspension for the concentrate being processed. This ensures that every particle is adequately exposed to the cyanide solution, maximizing leach completion. Also, off-bottom suspension takes the largest particles and only slightly lifts them off the bottom of the leaching vessel so they do not come in contact with the agitator blades, dramatically reducing mechanical wear. 

Ensuring There Is Enough Oxygen

Oxygen is often a limiting factor during the cyanidation process. Oxygen is key for driving the chemical reaction which causes gold to be pulled into solution. Without oxygen, leach time and leach completion are poor. Sometimes a gas sparging system is used to add oxygen to the slurry, but this can often be an expensive and unnecessary solution. 

Sepro offers a high performance oxidizing agent called Sepro Leach™. This compound is added to the slurry throughout the leaching process, ensuring there is enough oxygen for proper cyanidation to take place.

Increase Your Operations Revenue

Sepro Leach Reactors perform higher rates of gold recovery faster than standard leaching systems. Improving these processes help our clients to maintain their profitability, regardless of market conditions, year-in and year-out. Stop leaving money on the table, contact Sepro Mineral Systems today.