gravity dredge + modified sluice box = Need some help guys

[brobronek]

hi guys, it is pretty simple.
i metal detect, river snipe, pan, sluice and lately decided to modify my JOBE folding sluice box and try gravity dredging.
sluice modification:
i doubled the size, added a self classifier, some rubber corrugated matting under it for the fine gold recovery, 6 extra adjustable feet
I use 100 feet of 3 inches plastic pipe having at least 10+ feet drop

1)The first hard job was filling up the pipe to let the gravity do the job... it took me some time but was achieved.
Any fast and secure way to fill it up will be great?

2) my sluice box had i believe enough water going through it but a slight drop but was jamming after an hour or so with light rocks and send.
it catches gold but i would like to have the light stuff go with the water in order to work longer before clen up.

so please if you can have a look at the video and give me your thoughts.

this is the first gravity dredging video so others will be posted for some follow up. and better videos i will try
cheers everyone


https://youtu.be/r-UkVYrbuYY

 

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[arizau]

Just a couple of observations.

I think you may be running the sluice too flat. Important.....Usual rule of thumb for stream sluice setup is to place it so there is about 1 inch of drop for each foot of sluice and it looks like your sluice and flare is over 7 feet in total so you need about 7 or more inches of drop. With that steeper angle the sluice needs and can handle more water throughput but you could supplement the water flow by allowing more stream flow to enter the sluice along with the dredge supply and that would help to clear the sand and gravel allowing you to run longer between cleanups.

Good luck.

 

[brobronek]

Thanks a lot. I was thinking too that i didnt have enough drop but that would not be an issue because of the amount of water coming in. I guess you are right. A rookie mistake. Cheers

 

[spaghettigold]

the big riffels need more flow or pitch.A narrower sluice for the riffel section could help.The problem with raising your sluice by 7 inches is you will loose another 7 inches of drop that will further weaken your flow and suction.So.. narrowing the big riffel section or raise the water with a dam where you suck the material,laying the hose as straight as possible in to the river avoiding dips if possible also helps the flow.You can also weld some rods on top of them to help the bigger rocks slide .Also your fines section should be closed completely with the punchplate to avoid bigger rocks slide in(at 8 seconds in the vid)You can see the bigger rocks in the fines section at 1.49min. Then you need a punch plate with more openings per square inch to allow more waterflow in.Like the last part of your punch plate.

But it,s gravity dredging,always a bit tricky. You may find some tips in my thread http://www.treasurenet.com/forums/gold-prospecting/433395-8-inch-gravity-sluicing.html.

Cheers emilio

 

[brobronek]

thanks a lot emilio,
i will take time to go through your thread to try to learn more.
moreover, is there any efficient way to fill up the pipe?
it took me a couple of hours to go through the process.

 

[spaghettigold]

look at the second pic in post #4 in my thread.When the hose doesn,t have dips and enters the pool where you dredge low, it will fill itself .Requires some prep though.We lay the hose intake in the riverbed where we want to dredge and then build a little dam with plastiksheet and rocks around to create a pool with little higher water. Sorry brobonek i,m in hurry,preparing for a short trip.

Cheers emilio

 

[arizau]

An idea that may work(?) Cap the outlet end and pump the hose full with a bilge pump attached to a hose that extends into the dredge hose (maybe even full length if the main hose has some vertical rises). The inlet end may need to be above water to let displaced air escape until it is full.

As an after thought it may be easier to use the bilge pump to fill the hose from the bottom up if it can provide that much lift.

Good luck.

 

[brobronek]

look at the second pic in post #4 in my thread.When the hose doesn,t have dips and enters the pool where you dredge low, it will fill itself .Requires some prep though.We lay the hose intake in the riverbed where we want to dredge and then build a little dam with plastiksheet and rocks around to create a pool with little higher water. Sorry brobonek i,m in hurry,preparing for a short trip.

Cheers emilio

oh i see.
i always try to move light and just my equipment and gear is about 40 kg.
i like the concept... will try to figure out something similar.
cheers

 

[brobronek]

An idea that may work(?) Cap the outlet end and pump the hose full with a bilge pump attached to a hose that extends into the dredge hose (maybe even full length if the main hose has some vertical rises). The inlet end may need to be above water to let displaced air escape until it is full.

As an after thought it may be easier to use the bilge pump to fill the hose from the bottom up if it can provide that much lift.

Good luck.

hi Arizau, closing the end of the pipe with a cap is a great idea. it may actually work.
but using a pump isn't what i want to achieve to be honest.
I just want to keep it simple without any engine or pump.

 

[brobronek]

here is some of the good stuff i find in that river

 

[arizau]

hi Arizau, closing the end of the pipe with a cap is a great idea. it may actually work.
but using a pump isn't what i want to achieve to be honest.
I just want to keep it simple without any engine or pump.

I should have mentioned that what I was thinking about was a hand operated bilge pump something along the line of what is on this link. https://www.google.com/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=whale marine hand pumps

Anyway, good luck.

 

[kcm]

For a 100' run of 3" pipe, I'd suggest looking for a 3" to 4" adapter and then adding a 4" 1/4-turn valve. Close the valve to fill your pipe, then open the valve and get out of the way! Going with a 4" valve will allow full water flow through your pipe.

I'm unsure of your setup as I cannot afford the data time to watch your videos, but if your setup won't allow for a valve at the pipe end, consider adapting to 4", adding the 4" valve, then backing down to 3" again, but as close as possible to the outlet.

If your PVC pipe needs to be broken down for transport/storage, look at using rubber connectors. I recently purchased a few 3" from Amazon for a little over $5 each.

As for filling up the pipe, you could add a Y or a tee near the highest point of your pipe run, fitted with a screw-on cap or plug Problem with this is that after a while, air will seep in and may prevent maximum water flow. ...Not sure if they make them, but seems like I remember seeing (a long time ago) a rubber cap for use with PVC pipe. It was held on using standard hose clamp. Seems like the one I saw was for 6". That would make a sure seal, plus be easy to use and replace. If all else fails, use a piece of truck or tractor inner tube and a hose clamp. ...Could also use something like this on the discharge, but I would much more recommend a valve.

 

[brobronek]

For a 100' run of 3" pipe, I'd suggest looking for a 3" to 4" adapter and then adding a 4" 1/4-turn valve. Close the valve to fill your pipe, then open the valve and get out of the way! Going with a 4" valve will allow full water flow through your pipe.

I'm unsure of your setup as I cannot afford the data time to watch your videos, but if your setup won't allow for a valve at the pipe end, consider adapting to 4", adding the 4" valve, then backing down to 3" again, but as close as possible to the outlet.

If your PVC pipe needs to be broken down for transport/storage, look at using rubber connectors. I recently purchased a few 3" from Amazon for a little over $5 each.

As for filling up the pipe, you could add a Y or a tee near the highest point of your pipe run, fitted with a screw-on cap or plug Problem with this is that after a while, air will seep in and may prevent maximum water flow. ...Not sure if they make them, but seems like I remember seeing (a long time ago) a rubber cap for use with PVC pipe. It was held on using standard hose clamp. Seems like the one I saw was for 6". That would make a sure seal, plus be easy to use and replace. If all else fails, use a piece of truck or tractor inner tube and a hose clamp. ...Could also use something like this on the discharge, but I would much more recommend a valve.

Hi Kcm,
I like the idea of a tractor inner tube andca hose clamp.
Will try it this week end if tge weather allow it then make a video.
Appreciate all the good ideas and advices.
Regarding the pipe, i just hide it near the river. It is very safe overhere. No one touch nothing.
Cheers guys

 

[brobronek]

good morning all,
first of all, a small apology... i went to the river and made so many videos. after checking i came to realise that i was taking photos instead of recording.
To emilio, 7 inches drop for the sluice box was perfect and i used only the water coming out from the hose. However, there was no black sand or gold this time in the sluice. I believe that all the good stuff is still in the hose.
i would like to know if there is any other technique to trap the gold instead of having a sluice box at the end.
anyone tried something different as a gold + black sand concentrator?

 

[kcm]

Are you using PVC pipe (rigid) or some sort of hose (flexible)?

If PVC pipe, material "can" get stuck inside the pipe at the joints, whether the connectors are also PVC or whether they are rubber. However, it will catch very little material if the pipe is put together correctly. I like rubber connectors, as it is easy to break the sections apart.

If flexible hose, then you have a 100' long sluicebox.

...Can you post a couple pics of your operation?

 

[brobronek]

Are you using PVC pipe (rigid) or some sort of hose (flexible)?

If PVC pipe, material "can" get stuck inside the pipe at the joints, whether the connectors are also PVC or whether they are rubber. However, it will catch very little material if the pipe is put together correctly. I like rubber connectors, as it is easy to break the sections apart.

If flexible hose, then you have a 100' long sluicebox.

...Can you post a couple pics of your operation?

Iam using 100 feet of flexible hose. You can see the operation on the video i posted on the first post of this thread. I think you are 100/% right. 100 feet sluice box

 

[brobronek]

I was thinking that next time I don't take my sluice box, use the pipe for removing material for let say 4 to 5 hours, then keep the intake in the water, put the end of the hose in a 5 gallons bucket , put some heavy rock to stabilise it, then go back from the intake and advance feet by feet shaking the hose to make the black sand and gold move until it reaches the bucket.
What do you guys think about this?

 

[kcm]

Sorry, I don't have enough data time to view videos. I even usually have images disabled on my browser.

As for your other question, I'll shut up and leave that answer to someone more experienced. Good luck!

 

[arizau]

I think that is as good an idea as any AND I would try to keep the water flowing at the same time or maybe just cap it (maybe even both ends?) while you are trying to get the material to move down the tube.

Good luck.

 

[spaghettigold]

Ouf course the 7 inches of sluice tilt are a good advice,i just meant you should improove the flow first by building a little dam where you dredge for example ,in combination with a shorter section of hose.The dam will allow you to fill the hose effortlessly and the shorter hose simplifies to lay the hose down straight.Also you want,have to search long for rockjams and carry less weight to the river.

This is 19 feet of hose with only 2 feet of drop .But no dips.Worked not perfect but pretty well.Unfortunately i,ve had only a simple old phone for the vids and they have no audio on my computer.
I would not recommed to use no sluice box.
If you have heavily corrugated hose and only nuggets in your dirt you may catch most of it in the hose-as long as you are working the same site with the same low flow in your hose.But you will probably loose some fines and as soon you are working a spot where you have more waterforce the losses will be significant.I see you have beautyful gold there,fat pieces,don,t let them go back in the river .