fbtsomp63,
many thanks.
I am pretty sure that 75mm stormwater fittings are not generally available in Qld...certainly not at my local Bunnings. I will ty Home Timber & Hardware up here and also dedicated plumbing stores.
I have already made and tested a unit using 90mm and 65mm pipe (all from Bunnings) (kept other dimensions as per Daniels plans) and it seems to work...but think the 65mm pipe may be a bit tight to get the fluidisation water-bed principle to work properly.
My units is working OK but particularly good for re-processing already classified cons (1/8inch sieve seems to work well).
I am also using a 750GPH (US) 12V bilge pump thorough 19mm black garden irrigation type semi rigid poly pipe - with a tap....works OK but tap is fully open, so not sure I need the tap to regulate flow. I might do a more direct fit between pump and fluid bed concentrator and see what happens.
I threw some raw dirt (plus gravel and small stones) yesterday as a test run and it jammed up after about 10 handfuls of dirt. It certainly got rid of the fine dirt and soil
I've got some pretty fine but messy tailings ( fair bit of clay mixed in it)... I am gonna put through it today and see how I go...hopefully might find some yellow missed first time around.
Gonna keep playing with my prototype to see if I can get it to perfection and will post some pics soon.
I like Daniels idea of the banjo pan/sluice instead of a dustpan but it then becomes an expensive unit as those things sell for around $50 (incl freight).
thanks again