Did you know that fine gold recovery often makes up for most of the gold found by small-time prospectors? It is much more abundant and is usually found in places that are easier to get to. The problem with fine gold is that its very small and poorly installed sluice boxes can inadvertently let it through. To remedy the problem one must be aware of the main factors involved. The speed and volume of the water are critical! Even in a poorly designed gate, if you have the water volume and speed dialed in, you will still capture gold more effectively than using a high end professional gate that is poorly set up. Also, the angle at which the gate boxes are placed is also very important. The angle will affect the speed of the water as it descends, as well as how quickly the gate can be cleaned. If the angle is too shallow, larger rocks and bits of clay can settle on or around the rapids and cause turbulence in the water that will effectively kill the back-swirling action created by the rapids. It’s Will make you lose gold! Those points being the most critical, the next one is the construction and design of your lock. Their ability to catch gold and specifically fine gold is largely decided by the designs of the rifles or catch mat systems.
Finding the right water flow and speed for your circumstances is absolutely essential. It can be tricky and may require you to block the flow of water from your lock inlet or bring in additional water. This can be achieved by making a small rock dam on the stream or river bed. Depending on where you’re prospecting, this could be considered a violation of local Fish and Game laws, so watch out for them. Chances are, if moving rocks in the stream bed is considered an infraction, so is using a sluice box. Make sure you know the laws!
The larger the volume of water, the better, and generally speaking, it doesn’t hurt to fill the lock with water to the top of the sides if possible. A good recommended minimum depth is about 2 inches. The volume is usually separate from the speed of the water, so you can easily adjust it by lowering the gate further into the water or finding deep spots in the stream bed that act as a funnel for your gate.
Proper flow can be judged using small stones or a handful of sand. Place it at the entrance to your lock and watch how it flows. all but the heaviest particles should be washed out within 3-5 seconds, depending on the length of the gate. 3 is a bit fast but will allow much faster production of concentrates at the cost of losing some fine gold. 5 is a bit long or just about right depending on the coarseness of the material you are pouring. You should be catching a lot of fine gold at that speed, but you run the risk of bigger rocks getting caught in the rapids and disrupting the flow. However, you can adjust the angles to fix that.
When installing a gate, the proper angle must be observed. It is usually 5-7 degrees incline and should allow most rocks and round pebbles to pass through easily. You don’t want the material to slide, but to move slowly. An ideal speed is for a larger rock to clear itself within 3 to 5 seconds in a medium sized sluice box. Also remember that the angle affects the speed of the water as it travels down the gate. Also, it is sometimes impossible to get the angles right if the stream is very flat. In such a circumstance, you may need to create a makeshift dam with more rocks to raise the water level on one side so you can feed it through your lock. But that can be a lot of work, and it’s usually best to try to increase the speed of the water.
With the right angle, water flow and speed, now is the time to use our sluice boxes! Many people pre-screen their material before feeding it through the gate. It’s a lot of work and a properly configured gateway doesn’t need this. However, with that said, if you don’t pre-screen or sort your material, you’re likely to lose some fine gold. This problem can be fixed by using a grading screen above the lock entrance while shoveling dirt. I used an old dishwasher rack I found in the creek bed and put it at the entrance to my lockbox. the water went through it and as I throw the material it washes it away leaving the larger rocks and bits of clay for me to easily throw away. It’s a great lightweight solution that really speeds up my production. It’s also a much better alternative to dry filtering the material directly at the dig site and then hauling it over 10 feet to my lock. Your results may vary, but at this point you should have a pretty good intuition about the possibility of losing gold.
Removing the sluice gate from the stream can be a tricky process and will inevitably lead to the loss of some gold. It is strongly recommended that as you remove the water jet gate, you place a bucket or tray at the end to catch anything that may be accidentally washed away. I have seen unsuccessful attempts to remove a sluice gate causing small bits of gold to be washed out and returned to the stream. Be very careful.
After that, cleaning up is a piece of cake and not to mention fun. You can finally see how all your hard work paid off. However, it’s worth noting that if you have one of the state-of-the-art plastic sluices, you often have the added benefit of even easier cleaning, as well as a good view of what accumulates during the sluice process. The disadvantage is the lower production capacity.
Hopefully that will get any new prospectors started! I hope you enjoyed my guide!