Gold prospectors know that one of the biggest challenges is to separate fine gold from black sands and other heavy minerals. The chunkier nuggets and flakes can be picked out with tweezers, but those tiny specks of placer gold dust need to be separated another way.
Usually to separate gold from its primary source can prove to be time-consuming and difficult task. Because of this, ingenious prospectors have come up with a variety of different ways to capture this gold. The Blue Bowl Concentrator is perhaps the most popular tool created for this task.
Prepping A New Blue Bowl
Before beginning to use the blue bowl concentrator, the user needs to make sure that the interior of the blue bowl is dry and free of any oily substances that may cover it from the factory. To do that, the user can use a light dish detergent to get rid of any oily substances and needs to repeat this process several times until there is no noticeable residue.
Proper Setup of the Blue Bowl Concentrator
For the pump, a 12 volt submersible pump is usually recommended since its ideal for low pressure water supply. For the connection, the user needs to install a tee at the pump outlet and a ¾ inch of hose-bib fitting to the outer side of the tee. Then the connection is completed with the use of a garden hose to the ball-valve connection on the recovery unit.
However, a pump is more benefiting, since the air bubbles from the garden hose pipes may stick to sides or the bottom of the unit which in turn will slow down the separation process. Furthermore, there may be some 100 mesh loss of gold particles.
The concentrates should never be added dry. Wet the concentrations by adding a few drops of wetting agent with the water. This helps to breaks the surface tension between the concentrates and prevents any loss of micro fines by hindering their floating abilities. A few drops of a common dish detergent is a simple choice.
Preparing Concentrates to Run in the Blue Bowl
Gold-bearing concentrates from sluice or dredges needs to be screened down to at least 20 meshes for better results. Screening down to further will aid in recovery of the finest gold, but it adds more time to the whole process.
There are various methods of setting up a blue bowl concentrator. Place the bowl on top a five gallon plastic bucket and then level the bowl. There are triangular inserts on the top of the bucket, so that the bowl can easily set on the levelers. Use another ruler like leveler to make sure everything is on level.
The concentrates needs to be pre-screened to a specific mesh before adding them to the bowl. Classify the concentrates using several classifiers (usually 30, 50 and even 100 mesh). The higher the number of mesh, the higher the time required for processing but the better recovery of extra fine gold.
Adjust the water flow with the ball valve (approximately 2 gallons per minute), so that water is just slightly below the outer edge of the bowl and not over-flowing. Slowly feed the bowl with the concentrates and do not overload it with the concentrates. If over-fed, this may lead to build up of concentrates at the base of the center cone. The concentrates must reside on the outer side of the bowl for proper separation. To correct this, the user can use a turkey baster which easily pushes the concentrates to the side of the bowl.
The ball-valve should be opened up slowly and the water begins to create a spiral effect. The effect creates a riffled effect in the concentrates. Slowly increase the water flow and carefully monitor the effects of the flow on the concentrates until you not that the lighter material is discharged out of the cone, while the heavier gold stays in the bowl. At the end, shut off the water supply and use a suction device to suck out the find gold deposits.
Preventing Gold Losses
If the water flow is not constant and is too high, slow the flow down since most of the concentrates may end up in the retention bucket. If you are worried that you may have lost gold don’t be alarmed! The gold is safely contained in the 5-gallon bucket, so you can simply re-run the concentrates again if you are worried about losses.
The Simplicity of the Blue Bowl
The Blue Bowl Concentrator is the most popular fine gold separation tool on the market. It is the perfect combination of efficiency, simplicity, and low-cost. For the casual gold prospector it is the perfect solution for processing those buckets of black sand gold concentrates that you’ve been storing in your garage all winter.