After panning my concentrates down or running them through a spiral wheel I have always tossed out the concentrates, knowing that there was fine gold still in them. I knew that this fine gold can be separated from the material. One method I had heard of was with the use of mercury, but we know the dangers of mercury. I didn’t want my hair and teeth to fall out, lose my mind or my life. Nor do I want to take a chance at damaging the environment. I knew that there is a safe method to use mercury with a retort but I still didn’t want to chance it. I did some research and found some other methods that did not use mercury or chemicals such as the shaker table but that piece of equipment was much more than I wanted to spend, these were more for commercial operations. I found an article on miller tables, these are not some new technology I found that these date back to the 1800’s. A miller table works on a similar principle as a sluice box in that water flows through the box washing away the lighter material. The miller table does not have riffles like a sluice box but it has a slate bottom. You run the water very slowly so that it looks as smooth as glass and you have a mild pitch. I found some that sell on the market for around $150.00 which I think is very affordable but I thought that one would be easy enough to build myself. So with that in mind I had been saving some of my black sand concentrates over the past couple of years. I finally found the time to build one, it is nothing fancy, I used some scrap wood that was lying around the house, a piece of plywood and a couple of pressure treated spindles from deck railings. I used chalk board paint for the bottom. I bought a Pacifichydrostar submersible fountain pump from Harbor Freight Tools with a rate of 264 gallons per hour for around $12. I used 1 inch pvc for the plumbing with a ball valve to control the flow of water. I drilled holes in the pvc pipe for the spray bar. I used a 3/4″ hose from the pump to the plumbing. I sanded the plywood as smooth as possible then painted and then sanded and painted, I repeated this about 7 times. I assembled the plywood with the deck rails and sealed the joints with silicon. I assembled the plumbing and hooked up the pump with the 3/4 hose. I was ready to try it out. I plugged it in and I adjusted the water flow, I had the table sitting at a very mild slope I would have to say around 5 degrees. I had some black sand concentrates that I had been saving, I dumped them into the flow and it worked like a charm. It washed away the magnetite and the gold was left behind and I picked it up with my snuffer bottle.
It’s length is 3 feet by 8 inches wide, I have found that I could have made it shorter, 2 feet long would have been plenty. I find that it catches the gold in the first 6 inches.
The concentrates that I am running have already been processed through a spiral wheel and then classified through a fine mesh strainer. I have run the concentrates both wet and dry, either way works but I prefer running them dry just because of the way it lays down on the miller table as I feed the material.
Notice not much of a pitch, I have it sitting on two buckets that are different heights, the valve I have almost closed, I could have used a smaller cheaper pump if I wanted to. I feed the material slowly like I am sprinkling sugar on cereal.
I am very pleased with the performance of the miller table, I will no longer be tossing out my fine gold. The next one I build will be made of aluminum, this one is my prototype. I would prefer to use real slate but the chalkboard paint works fine. Very easy to build anyone can do it.