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Colorado Prospector club members -
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Concept of the sluice:
Basically a sluice box is your "controlled environment" where you the operator
create a creekbed copy that will do what mother nature does naturally.....pull or
seperate the gold and other heavier materials with the combination of water flow and gravity.
With this in mind we will continue with set
up and operation of your sluice.
There are several variables involved with set up/running a sluice box and it
will take a bit of practice to be fairly proficient at it.
Those major variables would be water flow, angle, and material type (classified or not,
and bedrock or placer)
For starters you will want to think about the overall length of
your sluice. Shoot for approximately 1 inch of angle per 12 inches
(3 foot sluice would be about 3 inches of incline from head to tail)
Look for a spot with decent water flow that will accomdate this incline,
and have a bit of room below the tail end for your tailings to drop off.
Too much tailings build up at the end can change the flow in the box.
Next make sure the spot you place the sluice is stable. Build up a rock
stack if needed to achieve the incline on either or both ends.
The tail end of the sluice need not be in the water.
We find it helpful to use a long rock that will span the sluice box and
place it about 1/3 the way down from the head of the sluice to keep the head
or "slick plate" of the sluice stable.
Make sure your box is level side to side and taking in the water current
as squarely head on as possible
This is where it can start to get sticky. The water flow into the sluice
is one of the variables I spoke of earlier and may also affect the previous
step as far as having to build up the head end with rock to achieve the proper
angle. Sometimes you have to build up this end because water flow is either
not enough or too much, both will frustrate your work so take the time to
get it right and your finds for the day will show it.
Here are a couple tips we use during set up that seem to work well........
We use our index finger to check depth in the riffle area, you want water
flowing at or near your second knuckle.
(about 1 1/2")
When the flow into the box is square and about the right depth you will
notice a "V" formation just above your top riffles, this is a good thing
as you will see when material hits it.
Too much angle will cause the water to "jump" or cavitate .....
Look for a smooth sine wave (S) kind of shape flowing over the riffles.
If your water is "jumping" then cut back on the angle.
Now you are ready to start feeding material into the box and dealing with
Some folks don't classify and prefer to shovel directly into the sluice....
we feel this can overload the box and allows much of the gold to travel
through while the box is in "overloaded" conditions.....remember this is
your "controlled area", keep it consistent.
We have also seen several setups (home made) that classify right in the
slick plate area.....
This can work well for larger gold and some of the
old timers used what were called "sluice forks" in the head area to keep
off the large stones.
Large stones setting down in your box will cause eddies in the current
to both sides of the stone and clear out any material there.
One concern we face here in Colorado is the fine gold which is why we shoot for that
consistency. The finer the gold, the harder it is to catch.
Now if you are going to go through all that work to dig up the gold and
get it into your controlled area, then you may as well try to catch it all!
If you are lucky enough to be digging where the gold is very coarse and of
an average larger size.....then you will find you can be more extreme with the variables.
Another little tip......classify your material with water!
Again, your "controlled environment" is only a few feet long.......when dry dirt is placed into
a sluice, there is a short period of time that it takes to actually get the dirt/gold wet.
This may only take a second or less but in the same time frame the dirt also traveled through
1/3-1/2 of your "controlled environment" or basically skipped right over it. This means you are
expecting the bottom of the sluice to catch your gold....this is not the "optimal" conditions
you were shooting for.
You may be runing placer material (rounded washed material) or bedrock digs
(sharp flat material)
Depending on which you will want to classify to different sizes.
We like our Keene A52 sluiced box and to start with we use a 1/2" classifier
for most placer material and we then go to 1/4" for sharp edged flat bedrocks
as they won't flow through the box as well..
We classify into a bucket and then feed the sluice with a small shovel from the bucket.
If for some reason you would want to run bedrock at 1/2" classification then you
will need to adjust one or both of the other variables. (angle and flow)
So.....your material is classified and the first load (shovel full) is fed in .......
feed it evenly and not too fast.......watch how the material flows into and through the box.....
is the material building up on one side and not the other?
If so you either have the box tilted from side to side or your water current isn't
hitting squarely, or both.
Adjust the box accordingly and then try another load.
While the material feeds into the box from the slick plate area, you will notice
that the heavier pieces leave that area last and when gold is present it should
slow down and/or stop on the black matting for a second or two (some specs will hold there).
The box should be able to clear the lighter material out in 15-30 seconds or so and heavier
material will stay behind each riffle....heaviest at the top riffles of course.
As the material flows through you will notice a "dancing" action of the material behind
each riffle.....that is exactly what you want.....Gold is 19 times heavier than water
and that little spot behind each riffle is the gold trapper! Old technology, that is still
where it's at today.
Once you have adjusted the variables to your liking and the conditions at hand,
then you are ready to just keep feeding. You can run the box until black sands
have built up enough behind the riffles that the "dancing" effect is hard to see.
This will vary depending on the box riffles and matting used but trust me...
that's alot of buckets before that happens....keep digging!
When you are ready to do a clean up .....carefully remove the rock at the upper
end while holding the sluice in it's positon at the head. Then pick up the sluice
bringing the tail end up just a little before the head so as to slow the flow down
as you pick up the box.
We use one of those black square tubs for clean outs, but a 5 gallon bucket works
just as well if you are careful. Remember...you have just worked your behind off
getting that material into the sluice and your "controlled environment".....
continue that theroy with clean out and panning.....use a controlled area (tub, bucket).
Hope you find these instructions helpful and may your pan turn yellow at clean up time!
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