Posted by HBprospector on April 10, 2009 at 11:08pm
Ok, so i built a four inch dredge and don't have the money nor the gold to buy the floats. I built a wooden stand,that work just fine i think? I have the sluice at a four inch drop from the header. I had a nine horse on it and the sluice still loaded up i tried different angles with it and no matter what it loaded up.So i put a eleven horse on it and at the four inch drop the sluice stay text book perfect. My problem is i think i that the riffles are packing up and i'm losing gold. I get some small gold and a ton of lead, ( bullets, split shot, buckshot, ect....). Oh also it is the keene three stage sluice.Keene sells the four inch dredge with a six and half horse, my question for any that can answer it is.1. Do i have to much power?2. Is that sluice only meant to be floated?3. What is a good test to see where if found would the bigger nuggets rest in the sluice?So that is where i'm at right now. The spot in my pic's we found some small but chunky gold.Some of it was still on the host rock.We hit hardpack at around four feet or so.Found no gold on the hardpack but in the over burden.Next weds we are going out to sample some more. I'm new to dredging as far as in the river/creeks, normally i just suck the banks.But now that i have air i have been going for the big gold if it's there.If there is little gold above the hardpack does that mean that the older bigger gold is between the hardpack and the bedrock?Also what is the best tool to break the hardpack?I know i have alot of questions and i apologize for that.Any who thanks for reading this in advance.Any advice would be very appreciated.Thanks for your help,Jeff; AKA...HBprospector
Dan,
thanks for the info.I didn't even think of splitting the hose into a blaster nozzel. i tried the 6.5 and it was not enough power because i have 25 ft of hose,and one of the spots i've gotten down to 35ft and still have not hit bedrock.that spot is on hold for now. i'm going to ajust the front of the sluice up an inch and see how that works. how can i fix the first two riffles? or is that the way they are?i'm building a 8ft sluice to put in down for the tailings to run through. thanks for the help. i'm going out one weds and i'll post some more pics when i get back.and some gold pics hopefully.
Your slope should be 1/2 to 1 in per foot of box..You are almost to much!!! All you need with a 4 is a 6.5 and a P180 pump...I have the same box and it dose look like the lower part is loading up but it is not..Play with the amount of opening on your lower fines area..Alot of black sand open it more...The first 2 riffels in the nugget area run full due to the way the water comes off the screen, 30% is on the high side for solids, even though you are rated at 5yds an hour....
For hard pan: Use some black abs pipe and make you a Y so you can run a 1 1/2 in blaster hose, works great..Alot better than the 3/4 that comes with the pump!!!
If you have more ???? Please ask that is what we are here for
Dan aka Goldhound
Joe,
Thanks for your advice i will check that out on weds for sure. I think that i might be sucking up way too much material. I will for sure ease up on the water/material intake.I read that it should be 30% material to 80% water.As far as the hardpack goes, i can not divert the creek the rangers tend to get bent on that kinda stuff.On your highbanker,what size engine are you running? I catch all the lead that runs through the sluice and alot of small gold i just think the bigger pieces of gold are not catching in the large riffle system.The sluice has two classifying screen at the head of the box,so any nuggets bigger than the screens just slide on into the large riffles and those are the only ones that load up.The high grade and the ultra fine run just perfect. I'll try different angles along with water flow and material control.
Oh, by the way, if you are not catching the bigger nuggets, bullets, etc. in the first few riffles; something is definitely wrong with angle or flow speed.
I'm no dredger, but I know from my testing that slurry speed over the riffles is extremely important. With a highbanker that is mainly a function of water speed, as the material is basically introduced right into the flow by the shovel full and does not alter the overall speed much. I think that by suction dredging you would have to be careful to have a consistent gravel/water ratio in order to maintain a consistent slurry speed over the riffles. If you get too much material in relation to the water, then it would be real easy to load up the riffles and they do have a hard time recovering. Once overloaded, it takes a lot of water energy to create the necessary vortices to scour off the packed gravel between riffles and get back down to the matting. On my highbanker, I have the water stream moving at 150gpm, but I don't think most dredge set-ups do that (nor should they depending on the type of riffles) and therefore maintaining a consistent slurry speed so as not to overload in the first place is real important. I guess one thing you could try is intentionally overloading the box and then running clear (water only, no gravel) and see if it will clean out the excess just as a way to correct the problem without having to perform a clean-up. As far as the hardpack goes: start upstream a ways and divert the river so that the area you want to work is left dry. Then you can use a pick and shovel on the harpack all the way down to bedrock. Hope this helps. LOL.
Comments
thanks for the info.I didn't even think of splitting the hose into a blaster nozzel. i tried the 6.5 and it was not enough power because i have 25 ft of hose,and one of the spots i've gotten down to 35ft and still have not hit bedrock.that spot is on hold for now. i'm going to ajust the front of the sluice up an inch and see how that works. how can i fix the first two riffles? or is that the way they are?i'm building a 8ft sluice to put in down for the tailings to run through. thanks for the help. i'm going out one weds and i'll post some more pics when i get back.and some gold pics hopefully.
For hard pan: Use some black abs pipe and make you a Y so you can run a 1 1/2 in blaster hose, works great..Alot better than the 3/4 that comes with the pump!!!
If you have more ???? Please ask that is what we are here for
Dan aka Goldhound
Thanks for your advice i will check that out on weds for sure. I think that i might be sucking up way too much material. I will for sure ease up on the water/material intake.I read that it should be 30% material to 80% water.As far as the hardpack goes, i can not divert the creek the rangers tend to get bent on that kinda stuff.On your highbanker,what size engine are you running? I catch all the lead that runs through the sluice and alot of small gold i just think the bigger pieces of gold are not catching in the large riffle system.The sluice has two classifying screen at the head of the box,so any nuggets bigger than the screens just slide on into the large riffles and those are the only ones that load up.The high grade and the ultra fine run just perfect. I'll try different angles along with water flow and material control.
Thanks for all your help.
Jeff