Building Recirculating sluice

[dchoff35]

I'm building a recirculating sluice box and I'm sizing my pump. What I'm using is an Angus MacKirk Foreman for a sluice which according to their instructions is to run 1.5 - 2in of water through the box at a decent rate. I have run it in a stream and from what I calculated is the stream was flowing at roughly 1 ft/s and this seemed to be working fairly well. The box is 11 in wide at the opening where I measure the water depth. When i calculated this out this turns out to be in a range of 3000 - 4100 gallons per hour, or 50 - 68 gallons per minute. Does this seem to be within a good range? Also please feel free to make any suggestions to how fast or how deep the water should be.

Also this whole system is going to have a grizzly with several stages to take the material down to 1/4in. Then it will flow through the sluice into half of a 50 gallon drum. There is going to be a couple of halves piped together so the dirt has time to settle out of the water.

 

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[goldenIrishman]

Ok... A reasonable question here but I feel that you're calculations are way off here. I run an 8 ft long X 1 ft wide custom sluice with a header box and it does just fine with a 1200 gph pump for the sluice and a 750 gph pump for the header box. Both flows combine in the actual sluice for a total of 1950 gph at max flow. I keep my box set at a 4 degree angle and it moves materials through it just fine.

Since you said it is a recirculating system the only question is one of how portable do you want it to be? 12 volt bilge pumps can be had with up to 2200 gph output from most boating supply stores and work very well for this job. if you don't want to have to keep charging batteries while using it at home you can hook the pumps up to the charger.

Your best bet would be to go with a pump that is larger than you'll actually need and install a valve that will allow you to adjust the flow as needed.

 

[Hard Prospector]

This does not sound like a portable system, in that case I would use (3) 40-60 gal. containers ran in series connected by 1.5" or 2" fittings and hoses. the cascading effect from tank to tank will help settle sediments out keeping the water clean much longer. Feed stores sell great galvanized steel or very hard plastic containers that work well and last a long time. Harbor Freight 3/4-1 HP (around 2800-3000gph) stainless steel dirty water pump should give plenty of flow especially if material is screened to 1/4". Home Depot for the fittings and miscl. hardware. Sounds like a fun project, good luck.

 

[goldenIrishman]

Hard Prospector brings up a very good point on the water containers. The more chance you give the water to settle out before it hits the pump again gives you two advantages. First it keeps the pump from dying an early death due to crud trying to get through it and second the water going through the sluice will be clearer. It's hard to see them "pickers" if the water is all dirty!

If you're classifying your material down to 1/4 inch then you need a lot less water to move it through the box than if it was larger. You're going to have to adjust it to find what works best for your setup. With materials classified down that small you should be good at 4-5 degrees with about a 1/2 inch or more of water over the riffles. Don't overload the box so the riffles get packed up and it will work fine.

 

[dchoff35]

The calculation for the volumetric flow rate is correct, I just think I'm running more water than i need. Also my calculation for the speed of the water was done by counting how long it took a leaf to flow through the sluice so that obviously open for alot of error. The only components I would take back and forth would be the sluice, battery, maybe pump, and other small items (pans buckets ect..) As for how portable, most of the system i planned on leaving the system set up in a spot for rest of the season here in South Dakota. So i had planned on cutting 2 50 gallon drums in halves for my water storage and then have them linked together in series by some pvc pipe. What i originally had in mind was to get a bilge pump that pumps 3000 gph and then i can always throttle it down with a valve, but the cost of a good battery to run it several hours would be almost more than just buying a small gas powered pump. Plus just discharging a normal car battery and then charging it usually ruins the battery quickly so i would have to replace the battery.

 

[goldenIrishman]

The valve is a good idea but I'd be careful on leaving anything on site unless you can secure it somehow. If you look through the forum here you'll see lots of tales about people that made that mistake.

Also be sure to check your local regulations to make sure that a gas powered pump is allowed. Motors attract attention where electric is nice and quiet.

 

[Brivic1]

Hello. I use this system and put a small vid on forum yesterday.. I am using a Rule 3700 pump[ Bilge] and I have 2 deepcycle batteries. It will almost flatten one in two hours. This is a nuicance after a while, and then the other goes in another hour or so.
A freind of mine has a 4 stroke honda charger that goes 12vdc as well as 125vac. Itwas a little noisy but would do the trick.
The material when clasified to 1/4 " went down OK, but at 3700 gph I could still clog it if I went to fast introducing material.
Having the material pre wetted seemed to help.. Cheers.

 

[TerryC]

1 1/2 to 2 inch connections TOO SMALL between tubs! Been there, done that! Make the connecting tubes at least 4 inch diameter to take the flow with extra to spare. Also, tie-wrap the end of the 1 1/2 hose into a tiny bucket to keep it up out of the sediments collecting in the bottom of the last tub. TTC

 

[dchoff35]

Very good idea Terry. My new current plan is to run a bilge pump off a deep cycle battery. Found a 12V 60W solar panel for fairly cheap so gonna add a battery charger controller to keep charging the battery. Wont be enough for constant running but it should help. Maybe only run it for an hour, do a clean out, then gather more dirt to run while the battery regains charge.