SLUICING FOR GOLD - How to work a sluice box
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WHEN YOU GET TO STEP SIX YOU WILL HAVE RUN SEVERAL HUNDRED POUNDS OF GRAVEL. FAR MORE THAN A PROSPECTOR COULD EVER HOPE TO PAN IN ONE DAY
There are many methods of prospecting for gold in the 1990's. The search for this precious metal includes panning, sluicing, dredging, dry washing and electronic metal detection.
Among the more popular sluice boxes in use today are these two lightweight aluminum models from Keene Engineering. The A51 Mini Sluice (right) weighs in at seven pounds, while the larger A52 Hand Sluice tips the scales at eleven pounds.
One of the most practical methods of gold prospecting and recovery involves the use of a piece of equipment that has been in use for over a hundred years. One of the very best gold gathering devices on the market today is still the Hand Sluice.
Sluice boxes were once built at the location of the mining site from the material that were on hand such as heavy wood planks and logs. Often the river current was diverted through the sluices so that gold-bearing gravels could be processed far quicker than using the laborious "hand panning" method. The old sluice boxes were lined with raised obstructions that were placed in a vertical position to the flow of the current. (These obstructions were later referred to as riffles)
When the gold-laden gavels were dumped into the upper end of the sluice, the flow of water carried the material down the length of the box. The lighter gavels (tailings) would be carried in suspension down the entire length of the sluice and then discharged. The heavier material (such as gold, platinum metals and black sands), would quickly drop to the bottom of the box, where they became entrapped by the riffles. Once the riffles collected a large quantity of concentrated black sand, a "cleanup" was implemented. The flow of water through the sluice would be diminished by a type of water gate. Then the riffles would be removed, allowing access to the heavier materials, which had collected during the "run." This remaining material or concentrate often contained all the values amounting to many tons of gravel which had to be tediously panned.
The sluice boxes in the days of the 49'ers were very similar to the ones of today. The primary difference is the construction and materials. Sluice boxes were built of heavy wood planks, because lumber was cheap and easily obtainable. Today's sluice boxes are constructed of light weight aluminum and steel.
Any miner or prospector will tell you that portability is the key to success. Most of the gold deposits that easily accessible have long since been depleted of their gold. Today you will have to "get off the beaten path" to find any virgin areas.
During the Gold Rush sluices were first used to work the extremely rich bench deposits "terrace" gavels" which lined the banks of many Mother Lode Rivers. As time passed it became clear that sluice boxes could be used for working other types of gold-bearing material, to include ancient river channel deposits located hundreds of feet above the existing stream beds. Modern prospectors use sluice boxes to work literally any type of gold-bearing gravel which can not be worked with a suction dredge. Sluice box's have been successfully used to process gold bearing gavels located in dry desert areas, by utilizing transported in water and recirculation systems.
In many cases today's prospectors use their sluice boxes to work areas located adjacent to flowing streams. Frequently, people who own suction dredges will carry in a lightweight sluice box to sample gravel bars they may wish to dredge at later date. If it turns out a gravel bar is not as rich as originally believed, all the labor of carrying in a large equipment may be avoided. For the benefit of those who are not familiar with the proper use of a sluice box, I will explain the basic principles involved. As you will learn shortly, they are not the least bit complicated. Anyone can be come a qualified "sluice operator" after just a few hours time spent in the field!
STEP 1: GETTING SET UP
After you have located a promising deposit of gold-bearing gravel, walk along the stream bank and look for a place where you can set up your sluice box. You should search for a spot where the current is moving quite swiftly. Once you find such a place, set your sluice box directly in the current so that the box is filled with water almost to the top. You can often compensate by placing the sluice box so that the upper "input" end is slightly higher than the lower "discharge" end. If the sluice box is somewhat unstable in the current, position a few rocks around the outside of the trough to brace it. Sometimes you will not even need the "rock brace," as the first few buckets of gravel placed into the sluice box will provide just enough stability to weigh it down.
Once you have located a good deposit of gold-bearing gravel set up your sluice box at any nearby place where the stream current Is flowing quite swiftly. The water depth should be nearly to the top of the sluice trough.
Transporting material to hand sluice in buckets.
Feed the gold-bearing gravel Into the upper end of the sluice box in carefully regulated amounts. Do not dump the entire bucket into the sluice box all at once. The proper Introduction of gravel will ensure maximum riffle efficiency and optimal fine gold recovery.
STEP 2: FEEDING THE SLUICE
Feed your gold-bearing gravel into the upper portion of the sluice box in carefully regulated amounts. Do not, under any circumstances, dump a large amount of gravel into the sluice box all at once! The gravel must be fed at a pace that will not overload the riffles. How can you tell when the riffles are overloading? It is simple. If you cannot see the uppermost "crest" of each riffle bar at all times, you are feeding the gravel too fast. Back off a bit. The use of a 1/4 inch classifier screen to pre-screen material before dumping into the sluice box can save much time and effort. The penalty for overloading your riffles often resullts in lost gold! Each time a new load of gravel is dumped into a sluice box with overloaded riffles, any gold in that gravel will wash right over the material that is clogging your riffles and out the discharge end of the box.
Classifier screens are available in many sizes to fit both gold pans and various size buckets
Check the black rubber matting for the occurance of values
STEP 3: CHECK THE SLUICE FOR VALUES
It is a good idea to periodically check the sluice box for values that may have been recovered. The black rubber matting is designed to make a quick inspection during the sluice operation. Gold can be spotted instantly on the black matting while the sluice is being fed. This helps to determine where the gold values may be the most plentiful. Remember, don't overload your riffles!
STEP 4: TENDING THE SLUICE
After dumping each load of gravel into the sluice box, check the riffle section for large waste rocks that may be lodged in the sluice. Flick these rocks out of the riffles with your fingers. When large rocks are allowed to rest in the riffle section they will cause the current to wash out all the concentrates from the immediate area of the rock. If a rock is lodged in the uppermost portion of the trough, the washed out concentrates will merely settle in the next few riffles down. But if the wash-out occurs at the lower end of the trough, the concentrate may flow out of the sluice box altogether. As one can see, it pays to keep an eye on those waste rocks! And one more thing, don't forget to shovel away the tailings which will periodically build up at the discharge end of the sluice box. If you don't the tailings will back up into the lower end of the sluice trough, burying some of your riffles.
Remove large rocks that may cause values to wash away.
Shovel the material that has built up at the end of the sluice to prevent any obstruction that may prevent the flow of material.
Remove the sluice's riffle section, screen, carpet and wash into a pan or bucket carfully.
STEP 5: PERFORMING THE CLEANUP
When your riffles have accumulated black iron sand in amounts extending more than halfway downward to the next lower riffle, it is time to perform a cleanup. Carefully lift the sluice box from the current keeping it as level as possible. Now carry it over to the stream bank (watch your footing on those slippery rocks!) and set it down. Remove the sluice's riffle section ans screen and set it aside, exercising care not to shake off any gravel adhering to it. Roll up the matting which lines the bottom of the sluice box trough and thoroughly rinse off all the concentrate. This should be done with the matting safely contained in a gold pan or deep bucket if possible. The use of a bucket may prevent any loss of all gold that could occur when attempting to rinse out the matting in a gold pan! Next, examine the empty sluice box trough.
Gold has a tendency to work its way beneath the matting which often lies at the bottom of the trough. You may be surprised at the amount of "color" that can accumulate there. Check to see if there is any fine silt clinging to the bottom, rinse all of it into your concentrate bucket.
Finally, pick up the riffle section itself and rinse any adhering gravel into the concentrate bucket. The sluice box cannot be considered "cleaned" until each and every part has been thoroughly rinsed.
After the riffle section has been removed, roll up the matting which lines the bottom of the sluice box trough and thoroughly rinse it off in a pan or bucket. The concentrate rinsed from the matting will contain most of the gold accumulated during the "run.
Once the sluice's bottom matting has been rinsed, check the empty trough for fine silt which may have worked its way beneath the matting. If silt is present, rinse all of it into the concentrate bucket. Also rinse off the riffle section and screen and black matting. You may be surprised at the amount of color that can accumulate!
The final step of the sluicing is the panning of the concentrates, to get the gold out. Do this very carefully, since the material in your pan contains all the gold once spread throughout the many hundreds of pounds of gravel you have processed through your sluice.
STEP 6: GETTING THE GOLD OUT
And now for the final step. This is the one you will certainly enjoy the most. The act of panning out your concentrates to get the gold. I hope your run was a profitable one!
By the time you get to Step Six, you will have processed several hundred pounds of gravel, far more than the average person could ever hope to hand-pan during a daily outing. Using a sluice box of the type shown, you can also work this much gravel. All you need is a sturdy shovel, a couple of good buckets to carry gravel to the creek, and if your fortunate, a mining partner to feed the sluice box while you dig gravel, and a solid desire to get that gold.