Sluices and Fine Gold

For thousands of years, sluices have been used to separate gold from the ground. From 40-foot “long toms” to Z sluices, the idea has stayed the same… heavy gold stays and light materials get washed away. That was all good when miners were after nuggets and chunky gold, but now the focus is on fine flour gold. That is a whole different gold… and the focus of this article.

For most miners, fine gold is defined as sub 100 mesh size. Although some is caught in standard wash plants sluices, this is more of an accidental capture along with the larger pieces. When this size is your primary target, there are a few things to remember.

  1. Larger material running in the sluice will knock out fine gold.
  2. Too much water flow will not capture fine gold.
  3. Small gold will attach itself to air bubbles and never get caught.
  4. A substantial amount of flour gold actually floats.
Sluices targeted to fine gold should be designed so that you can:
  • Control the water flow over it separately from the water used to wash the pay.
  • Use slower gentle water verses fast agitated water
  • Have a system to break the surface tension to capture the floating gold.
  • Separate water flow is more commonly found using reverse trommel.
  • Slower gentle water eliminates the air bubbles that help fines to ride down the sluice.
  • A simple light flap of material (like a mud flap) over the sluice will help break surface tension driving the floating gold underwater where you have a 90% chance of capturing it. For a sample of this use of a flap,  see our Video below:

Although an old report, a study done by one of the best-known experts in sluice design and management, Randy Clarkson, is a great read for both hand and mechanical miners. That report can be found at:

https://www.scribd.com/doc/61880538/The-Clarkson-Study-Fine-Gold-Recovery

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