Sluicing For Gold
The sluice box is lined with raised
obstructions called riffles. They are
placed at even distances in a vertical
position to the flow of the water. When the gold bearing gravels are dumped
into the upper end of the box, the flow of the water carries the materials down
the length of the box. The lighter gravel will be carried in suspension the
entire length of the sluice and then discharged. The heavy material such as gold, black sand, lead and
iron, quickly drop to the bottom of the box and are trapped by the riffles.
Sluicing is a very easy and inexpensive way to process a lot of gravel. You can pick up a nice light aluminum box for a very reasonable amount. Most boxes run between $50 and $150. Sluice boxes come in either straight or flare. A straight box is a lot easier to move around while packing because it's much narrower. A flare box is nice because they gather more water so you can run gravel faster and there's more room to dump gravel. Most boxes manufactured today are 24 to 60 inches long. The longer a box is, the more gravel you can process before you need to clean it out.
Tools you're going to need.
In addition to the tools you would normally be carrying in you backpack while looking for gold. You will need a few extra things for sluicing, such as - 1 or 2 - 5 gallon buckets. A shovel, and a classifier.
Setting up the sluice box
When setting up a sluice box you need to find a place where the current is moving swiftly as close as possible to the area you want to work. You will set the box directly in the current. The trick is to find a spot close to the edge that will hold the box and allow you to have a little bit of drop to the box. You will most likely need to lay a couple of large rocks against the box to hold it in place. You want to be able to gather as much water as possible through the box. You may have to build a small wing dam with rocks on each side of the box to gather the water needed. You want the flow in the box at least ¾ full. A general rule of thumb is to have 1 inch of dropped per foot of box. If you have a 4 foot long box the discharge and should be 4 inches lower than the intake end.
Testing the flow.
Once you have the box set up you will want to check the flow. To do this you will need to run some gravel through it. When feeding gravel into the upper portion of the sluice be careful to regulate the amount. You don't want to dump a large amount at one time and overload the riffles. You should always be able to see the top part of the riffle while feeding gravel. After you've dumped your gravel into the box, let the clear water flow for a minute or so. Ideally you want 2/3's of the space between riffles clear of gravel. If there is only a very small amount of material behind the riffle, the box is too steep. If the area between the riffles stays full of gravel, then the box is too flat.
Feeding the box.
Once you have the flow properly set up in the box, you can start processing your gravel. While feeding the gravel into the box, be sure to remove any rocks that do not flow out. If you classify your material down to 1/2 to 1 inch it will flow through the box much better and speed things up. Always be sure to wash off the material in the classifier before discarding it, to make sure you're not throwing away any nice nuggets. If your box has a section of black rubber matting, it will make it easy to spot any pieces of gold in the box. This helps to determine whether or not there is any gold in the area you're working, without breaking down the box and panning. You will need to keep an eye on the discharge end of the box, make sure you're overburdened does not back up into the box. After a while you will need to check the box to make sure concentrates haven't built up too much. When the black sand concentrates accumulate down to below the halfway point, Its a good time to stop and clean the box. The easiest way to check this is to stop the flow of the water. You can use a flat piece of wood across the front of the box to stop the flow or you can use a gate in the box ( A small rectangle of aluminum that seals against the sides and bottom of the box ) to stop the flow.
Cleaning the box.
Once the box is full of concentrates, its time to clean up. To do this you must remove the box from the creek. When removing the box, raise the discharge end up slowly, to stop the flow. Once the flow has stopped, you can raise the intake up slowly, while letting the water run out. Make sure no gravel leaves with it. Take the box over to the edge of the creek. If you have a 5 gallon bucket slide the discharge end into the bucket. Be sure to unlatch the riffles before doing this. While holding the box at a 45° angle you can use your pan to wash the material out of the sluice into the bucket. Once most of the material is washed down, loosen the riffles and rinse them off. Then you can get them out of the way. Let the carpet slide into the bucket. Make sure you rinse every last bit of material out of the box into the bucket. Once the boxs is clean, you can set it aside. Now you can fill your 5 gallon bucket to the top with water. Reach in and stand the carpet up on end. You'll have to roll it up a bit to do this. But make sure it's not rolled any tighter than it needs to be. You want it as lose as possible in the bucket. Now raise it up and down quickly in the water to wash off all material. Remove it very carefully and roll it back out in the sluice box. You can do a quick check to make sure that no pieces of gold are hung up in it. Then you can reassemble the sluice box. Now all that's left to do, is pan out your concentrates in a 5 gallon bucket.
Sluicing is a very easy and inexpensive way to process a lot of gravel. You can pick up a nice light aluminum box for a very reasonable amount. Most boxes run between $50 and $150. Sluice boxes come in either straight or flare. A straight box is a lot easier to move around while packing because it's much narrower. A flare box is nice because they gather more water so you can run gravel faster and there's more room to dump gravel. Most boxes manufactured today are 24 to 60 inches long. The longer a box is, the more gravel you can process before you need to clean it out.
Tools you're going to need.
In addition to the tools you would normally be carrying in you backpack while looking for gold. You will need a few extra things for sluicing, such as - 1 or 2 - 5 gallon buckets. A shovel, and a classifier.
Setting up the sluice box
When setting up a sluice box you need to find a place where the current is moving swiftly as close as possible to the area you want to work. You will set the box directly in the current. The trick is to find a spot close to the edge that will hold the box and allow you to have a little bit of drop to the box. You will most likely need to lay a couple of large rocks against the box to hold it in place. You want to be able to gather as much water as possible through the box. You may have to build a small wing dam with rocks on each side of the box to gather the water needed. You want the flow in the box at least ¾ full. A general rule of thumb is to have 1 inch of dropped per foot of box. If you have a 4 foot long box the discharge and should be 4 inches lower than the intake end.
Testing the flow.
Once you have the box set up you will want to check the flow. To do this you will need to run some gravel through it. When feeding gravel into the upper portion of the sluice be careful to regulate the amount. You don't want to dump a large amount at one time and overload the riffles. You should always be able to see the top part of the riffle while feeding gravel. After you've dumped your gravel into the box, let the clear water flow for a minute or so. Ideally you want 2/3's of the space between riffles clear of gravel. If there is only a very small amount of material behind the riffle, the box is too steep. If the area between the riffles stays full of gravel, then the box is too flat.
Feeding the box.
Once you have the flow properly set up in the box, you can start processing your gravel. While feeding the gravel into the box, be sure to remove any rocks that do not flow out. If you classify your material down to 1/2 to 1 inch it will flow through the box much better and speed things up. Always be sure to wash off the material in the classifier before discarding it, to make sure you're not throwing away any nice nuggets. If your box has a section of black rubber matting, it will make it easy to spot any pieces of gold in the box. This helps to determine whether or not there is any gold in the area you're working, without breaking down the box and panning. You will need to keep an eye on the discharge end of the box, make sure you're overburdened does not back up into the box. After a while you will need to check the box to make sure concentrates haven't built up too much. When the black sand concentrates accumulate down to below the halfway point, Its a good time to stop and clean the box. The easiest way to check this is to stop the flow of the water. You can use a flat piece of wood across the front of the box to stop the flow or you can use a gate in the box ( A small rectangle of aluminum that seals against the sides and bottom of the box ) to stop the flow.
Cleaning the box.
Once the box is full of concentrates, its time to clean up. To do this you must remove the box from the creek. When removing the box, raise the discharge end up slowly, to stop the flow. Once the flow has stopped, you can raise the intake up slowly, while letting the water run out. Make sure no gravel leaves with it. Take the box over to the edge of the creek. If you have a 5 gallon bucket slide the discharge end into the bucket. Be sure to unlatch the riffles before doing this. While holding the box at a 45° angle you can use your pan to wash the material out of the sluice into the bucket. Once most of the material is washed down, loosen the riffles and rinse them off. Then you can get them out of the way. Let the carpet slide into the bucket. Make sure you rinse every last bit of material out of the box into the bucket. Once the boxs is clean, you can set it aside. Now you can fill your 5 gallon bucket to the top with water. Reach in and stand the carpet up on end. You'll have to roll it up a bit to do this. But make sure it's not rolled any tighter than it needs to be. You want it as lose as possible in the bucket. Now raise it up and down quickly in the water to wash off all material. Remove it very carefully and roll it back out in the sluice box. You can do a quick check to make sure that no pieces of gold are hung up in it. Then you can reassemble the sluice box. Now all that's left to do, is pan out your concentrates in a 5 gallon bucket.
|
|