Need help with dredge sluice

[jaguargene]

I'm building a dredge sluice.I'm having 3 sets of riffles made for a 8 foot X 16 inch wide sluice.My pump is the keene P350 with 450 gpm with a 4 inch hose and nozzle. My riffles size is

3/8 inchs high X 15 1/4 inchs wide X 24 inchs long X 1 1/2 inchs space between them


3/4 inchs high X 15 1/4 inchs wide X 24 inchs long X 1 1/2 inchs space between them


1 1/4 inchs high X X 15 1/4 inchs wide X 36 inchs long X 4 1/2 inchs space between them

I was thinking put the 3/8 a the top and then 3/4 with aspace of 1 foot then 1 1/4 riffle at the bottom.
My question is do I need riffles on top to make a duel layer riffles or just punch plates to slow the water flow down and retain more fine gold.Thanks for any help.

[nuggy]

Hi J G - Probably just looking at the photos in this section and reading the threads will help, with what you are doing - that seems like a BIG pump and sluice box for a four inch dredge. What size is the motor?
Riffles catch gold on their downstream end so a riffle at the bottom of the box would retain little or nothing. Most would decrease the height of riffles down the box if they change at all.
Lots of photos of good rigs in here check them out. Nuggy

[strickman]

3/8 riffles seem small.

[russau]

if it were my sluice, id forget about the 1 1/4 riffels and have slick plate at the head of the sluice and push the rest of the riffels sets down to accomodate the slick plate. 8 foot of riffels seems tobe to much even with the bigger pump.and id have some screen over them small riffels.i only have 4 riffels that are 3/4 in. tall and the rest of it is 1/4 raised expanded screen over carpet(Shaw). miners moss loaded up to much when the eng. was stopped or slowed down and packed itself and couldnt unpack when started back up.as of yet since my rebuild of my sluice i havent had a chance to get it into the water.but every week ive been watching the weather all over the country.

[jaguargene]

I have a 11hp.which I plan on running at about halr rpms.

[russau]

i should have asked what size gold are you normally getting before i said to drop the 1 1/4 riffels!

[2cmorau]

let the environment dictate what equipment you need
what is the most common size cobble large or small
how deep do you need to go to bedrock
that box would be great for a six inch, however one inch riffle with a punch plate in the upper 1/4 of box might work
big GOLD or small gold
jsut guessing on my part

[Jason in Enid]

Your sluice box is the right width for a 4 inch sluice, but there's really no need for it to be 8 feet long. That is serious overkill. Same with the pump and motor. You could pull a hand off with the suction that thing will be putting out.

Run your sluicebox like Keene's new triples. The over/under design works great and saves a ton of room. One more thing, if you are set on the length then make the first couple feet slickplate to give the gold plenty of room to stratify.

[russau]

18 inchs is the MAX. id have for a slickplate!anything else is a waste.