Introducing the Sepro Frontier Bowl
Written By: Team Sepro | Date: 09.05.22
Learn why the Sepro Frontier Bowl represents the first significant improvement in gravity gold recovery in more than 20 years. This innovative centrifuge bowl design achieves higher gold recovery than traditional bowl profiles under most test conditions.
That’s right – whether you’re looking to recover coarse gold particles or fine gold, the Frontier bowl is likely going to immediately improve your operation’s output. Read on to learn more!
Knelson vs Falcon Concentrators – What’s The Difference?
Before we can learn why the Sepro Frontier bowl excels under most test conditions, we must understand the baseline differences between the Knelson and Falcon concentrators.
Comparing the two designs, we see a couple of design differences:
- The Knelson™ concentrator consists of an inclined, constant-angle bowl wall and fluidized riffles along the entire height of the bowl. This design has been essentially unchanged since the initial development.
- The Falcon concentrator began as a nearvertical, smooth-walled bowl specifically designed for fine gold recovery. Over time, the Falcon SB concentrator bowl evolved and now consists of an inclined, smooth-walled separation zone followed by a vertical recovery zone with fluidized riffles.
These differences in bowl geometry result in a significantly different concentration mechanism between the two centrifuges. The key difference between the two types of centrifuges is that the bowl angle of the Knelson™ concentrator is shallower than the angle of the dynamic slurry face, while the bowl angle of the Falcon concentrator is steeper.
Sepro Frontier Bowl – The Best of Both Worlds
Our engineers at Sepro wanted to have riffles on both sides of the dynamic slurry face so that the concentration mechanisms from both the Knelson™ and Falcon concentrators could be utilized.
To this end, Sepro tested an innovative new bowl geometry with a quasi-parabolic riffle profile, the Frontier™ bowl. The concept behind the parabolic riffle profile was to create a bowl with riffles on both sides of the dynamic slurry face.
Using this design, we wanted a smooth path for slurry flow up the bowl wall. Under ideal design conditions, the bottom riffles begin with a relative angle of 30 degrees and progressively decrease in angle until the top riffles are vertical.
Initial Results – Higher Gold Recovery
The Sepro Frontier™ bowl achieved significantly higher recoveries than the Knelson™ and the Falcon bowl profiles across multiple tests.
The Frontier bowl achieved almost 20% higher recovery on the high-grade ore with coarser gold particles (65% vs 55%) and almost 50% higher recovery on the low-grade ore with finer gold particles (65% vs 45%). The size-by-size gold recovery analysis identified improved recovery across a range of gold particle sizes with dramatic and consistent recovery improvements in particle size ranges below 100 microns.
The Frontier™ bowl achieved these recovery improvements under all test conditions. From this information, we can infer that combining both concentration mechanisms (along with a smooth transition zone) dramatically improves overall gold recovery across a range of ore types, gold grades and particle sizes. Based on the significantly higher performance of the Frontier™ bowl in the Falcon SB400, Sepro decided to proceed with comparative testing in an operating plant environment.
Plant Test Results – What Does This Mean for Your Operation?
Sepro produced a Frontier™ bowl that fit as a direct replacement part in a Knelson™ XD48 gravity concentration. The bowl was installed at a gold mine in North America currently operating two Knelson™ XD48 gravity concentrators with the standard Knelson™ riffle profile.
Tests were run on each bowl over two days, using the standard plant settings for feed rate, bowl speed, fluidization flow rate, and concentration cycle times. The standard Knelson™ bowl achieved a cyclone overflow grade of 11.0 g/t Au while the Sepro Frontier™ bowl reduced the cyclone overflow grade to 5.8 g/t Au, a 47% improvement.
With the Knelson™ bowl installed, the gravity circuit achieved an average gold recovery of 18%. With the Frontier™ bowl installed, the gravity circuit achieved an average gold recovery of 54%, representing a relative increase of 300%.
Install a Sepro Frontier Bowl to Improve Your Gravity Circuit
Altogether, the Sepro Frontier bowl has established the following benefits:
- 20% higher recovery on the high-grade ore with coarser gold particles (65% vs 55%)
- 50% higher recovery on the low-grade ore with finer gold particles
- Reduced cyclone overflow grade from 11.0g/t Au to 5.8 g/t Au, a 47% improvement
- Improved gold recovery from 18% to 54%, a relative increase of 300%
The Sepro Frontier™ bowl represents the first significant improvement in gravity gold recovery in more than 20 years, and we expect it will improve recoveries around the gold mining industry. You can download the full whitepaper here to learn more about the new Sepro Frontier bowl.