I am totally new to this aspect of gold recovery so I am looking for pointers and sources of dredge making supplies and any tips.
Has anybody made their own dredge?
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Geo
Well-known member
it really depends on the size and how much you want to do. ive converted two highbankers to dredges before. if you want to work a small stream (Lets say less than over your head) a 2" pump should work fine. a dredge is basically a floating sluice. suction is produced at the nozzle by the venturi effect. if the dredges hose is like 15' to 20' you may want to go up to a 3" pump or two 2" pumps. the the pumps pressure comes into the venturi coupling at the header box. consider the picture as a starter kit. a couple of pontoons as a platform. one man should be able to pull it with no problem.
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philddreamer
Well-known member
I made 4" dredge back in 2008; a used a 5hp B&S & pump from a 3" dredge. I made the power jet from a 4" aluminum tubing. I bought some hose, used inner tubes for floatation; made the sluice box out of aluminum & the riffles out of light guage steel.
I'll try to post some pic's tomorrow, if a can get some copies from my back up HD, the main PC went kaput!
Phil
P.S.:
Found them!
I'll try to post some pic's tomorrow, if a can get some copies from my back up HD, the main PC went kaput!
Phil
P.S.:
Found them!
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philddreamer
Well-known member
One thing to keep in mind, the higher the power jet is from the surface of the water, the more horse power needed in order to have enough suction at the end of the nozzle, thus clearing the hose of all the material that was picked up. For a 4" dredge, 6HP or higher is recommended.
Phil
Phil
NoIdea
Well-known member
Years ago when i was a boy, not saying im now a girl, no! no! no! :mrgreen:. I did some dredging use a very very similar set up, except the water pump was attached to a standard lawnmower moter, this was mounted on a platform which sat on an innertube with the pump submerged through the center of the tube, if you get my drift. The venture system was located at the suction end. The pump had a mesh attached to prevent debre entering. I worked under water, with proper breathing equipment and air pump, only a summer job.
Deano
Deano
philddreamer
Well-known member
Yeap, I'm familiar with that type of dredge! I have a 2" old dredge that's design that way.
Phil
Phil
urbanminer
Member
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- Aug 30, 2009
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Check out some of the gold prospecting forums. Many of them have free downloads of plans to make equipment. Keene or proline are a couple of the major manufacturers of dredge accessories and most parts can be purchased from them. If you want a ready built dredge, try to find one in California. They are selling cheap!
Thanks for the reply's, I have a friend in Central America who has leased land for a placer operation in a small stream. His preliminary panning yielded rice sized placer gold.
I described to him how to build a riffle out of plywood with a "green grass carpeting" base and a grid to hold it down. A 2" water pump will supply the water and shovels and buckets will supply the stream bottoms. I was hoping to find some how to plans to build a riffle to send him on the internet.
If the riffle pays the next upgrade is a dredge but starting out on a budget a wooden riffle and his existing pump seems like a good way to test larger areas rather than just panning.
I described to him how to build a riffle out of plywood with a "green grass carpeting" base and a grid to hold it down. A 2" water pump will supply the water and shovels and buckets will supply the stream bottoms. I was hoping to find some how to plans to build a riffle to send him on the internet.
If the riffle pays the next upgrade is a dredge but starting out on a budget a wooden riffle and his existing pump seems like a good way to test larger areas rather than just panning.
Geo
Well-known member
a very low tech way to get some concentrates (and i swear it works) is to cut a square piece of carpet (shag works best) a few yards square and find a place where the current is swift. place the carpet flat on the bottom and weight it down on four corners in the swift current and shovel sand and gravel on the upstream side. if the current is strong enough, you can continue adding without stopping. keep the downstream open so the current doesnt back up.when you finish after loading the carpet with sand, let the current wash it for an hour to remove as much over burden as it can. when the fiber shows back through the sand, gently roll it up from the downstream side. it will be heavy. stand it up in a wash tub and wash the sand down into the tub. save that piece and use another the next day. when the carpet dries, spread it fiber down on a tarp and beat it (i used a boat paddle) you would be amazed at the gold a piece of shag carpet will catch.
blueduck
Well-known member
while i have not built my own dredge, i have run a couple and have thought about building one a time or two or improving an existing one. From what i read your friend has rices sized nuggets/pickers which would make them able to pass through about 10-12 mesh, for the most part and an 8 mesh screen most all the time unless its really long wire type gold. Such would be a great candidate for a Gold Cube which uses about 1100 gallon per hour 12 volt pump and can process from what the inventors claim up to 1000 pounds of classified material per hour or about a half a yard for such a little tool, i have not had that kind of volume yet to try to run on a timed basis, though i hope to this summer yet... we will see what it will eat, but right now i have no trouble feeding it a five gallon bucket in 5-7 minutes with a large trowel.
A suction dredge needs to have a specific pump on it, made for pressure and volume, trash pumps just wont produce the pressure needed for sucking up gravels as well as a dredge pump does. The "jet flare" design uses a short hose to feed water to the venturi and flare /crash box, as opposed to the older style using a long hose running out to the suction nozzle which adds both weight and expense as these hoses need to be pressure rated and not collapse, those pictures above show clearly a nice yellow dredge pump.
When you increase hose diameter size by one inch you can move 4 times the material from that next size down, however as the hose size increases so do the size of rocks you pick up and run over your sluice and the higher volume of water it takes to move them off, as that happens your finer gold will not always settle into your sluice and goes over the end of the dredge, so increased volume of material sometimes gives up that fine gold which really does add up over time. there are various designs of sluices to remedy this problem but they all still lose much of that fine gold. Ive run a dredge and shut down after 30-45 minutes and my riffles were full of black sands and gold, and ran all day long 4-8 hours and clean up was the same, no more fine gold than short runs in the same material.....makes me wonder how much ive lost over time......
you can build a dredge on legs, or floation, and the floatation can be inner tubes to a pontoon boat, the bigger boat has its pros and cons same as one you just set up on the bank.
most of the little backpack style dredges i retail about only 60- 65 pounds total weight [shipping weight is slightly higher though] but the drawback is its a 2 inch and 2.5 inch [measured at the intake nozzle] and though its good for sampling if you have to go very deep, there is no air onboard, and not enough power to pull the gravels if they are very deep [over 6 feet], but you do not lose as much fine gold with some of them,basiclly there is not much difference between highbnaker conversions and the smaller backpack style dredges with the exception of using a flare attachment design and single hose over double hose length. And of course as you go up in size you increase the weight of the motor/pump/air pump and need larger pontoons to keep the sluice floating when you are running, but you can move a lot more material
volume,thus increasing your intake of the yellow metal inlarger pieces at the end of the day...
If you have specific questions, ask and i and others will try to answer them, though tis the season and it may be a few days til i get back..... lol\
William
Idaho
www.diggitprospecting.com
A suction dredge needs to have a specific pump on it, made for pressure and volume, trash pumps just wont produce the pressure needed for sucking up gravels as well as a dredge pump does. The "jet flare" design uses a short hose to feed water to the venturi and flare /crash box, as opposed to the older style using a long hose running out to the suction nozzle which adds both weight and expense as these hoses need to be pressure rated and not collapse, those pictures above show clearly a nice yellow dredge pump.
When you increase hose diameter size by one inch you can move 4 times the material from that next size down, however as the hose size increases so do the size of rocks you pick up and run over your sluice and the higher volume of water it takes to move them off, as that happens your finer gold will not always settle into your sluice and goes over the end of the dredge, so increased volume of material sometimes gives up that fine gold which really does add up over time. there are various designs of sluices to remedy this problem but they all still lose much of that fine gold. Ive run a dredge and shut down after 30-45 minutes and my riffles were full of black sands and gold, and ran all day long 4-8 hours and clean up was the same, no more fine gold than short runs in the same material.....makes me wonder how much ive lost over time......
you can build a dredge on legs, or floation, and the floatation can be inner tubes to a pontoon boat, the bigger boat has its pros and cons same as one you just set up on the bank.
most of the little backpack style dredges i retail about only 60- 65 pounds total weight [shipping weight is slightly higher though] but the drawback is its a 2 inch and 2.5 inch [measured at the intake nozzle] and though its good for sampling if you have to go very deep, there is no air onboard, and not enough power to pull the gravels if they are very deep [over 6 feet], but you do not lose as much fine gold with some of them,basiclly there is not much difference between highbnaker conversions and the smaller backpack style dredges with the exception of using a flare attachment design and single hose over double hose length. And of course as you go up in size you increase the weight of the motor/pump/air pump and need larger pontoons to keep the sluice floating when you are running, but you can move a lot more material
volume,thus increasing your intake of the yellow metal inlarger pieces at the end of the day...
If you have specific questions, ask and i and others will try to answer them, though tis the season and it may be a few days til i get back..... lol\
William
Idaho
www.diggitprospecting.com
Long toms,or a sluice box can be made from wood or metal, there are different ways the riffle's can be made, it can be as simple as a wood slat frame , or a little more complicated to build as angled iron, welded on a frame, these later riffles are a more proven design, I have built several dredges, nothing real fancy but they work for me,made some jet flares, and I have even bent and welded up my own suction nozzles. aluminum sheet metal is easy to bend for the sluice box if you have access to a sheet metal brake, if not a simple metal brake can be constructed from boards clamps and large door hinges, angle iron can be welded to form the riffles and its frame, an outdoor carpet (looks like grass) under the riffle frame can also help to catch gold.
There are a couple of web sites on how to build a dredge or other mining equipment, also studying some of the professional ones like keen can help you design your own.
here is a quick search on riffles:
http://www.bing.com/images/search?q=dredge+riffle+desighn&view=detail&id=DBAEE4EAFA7DCFCFB14AEB4EB0941CDF96E97780&first=1
There are a couple of web sites on how to build a dredge or other mining equipment, also studying some of the professional ones like keen can help you design your own.
here is a quick search on riffles:
http://www.bing.com/images/search?q=dredge+riffle+desighn&view=detail&id=DBAEE4EAFA7DCFCFB14AEB4EB0941CDF96E97780&first=1
grance
Well-known member
glad I found this topic I'm thinking of building a high banker/floating dredge useing poly drums as pontoons Witch could be removed for use as a high banker. The sluce box i have is 10in X 36in. One thing I'm not sure about is how many GHP pump should I look for. I'm trying to keep it as light as possible and cheap. ive seen many use a honda engine with a keen or proline pump but there all 600-750 dollar range thats to much. Also seen a few cheaper pumps for around 200 bucks that deliver 1500-3000 Gph
