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Centrifugal Blower for a Gold Dryblower

Goodaye from Australia Dan, sorry if topic is off the mark , I have built a large Gold Dryblower, 15 ton an hour, the two large screens that the fines run over have dozens of holes that air blows through and the dirt blows off while the gold particles with a heavier SG get lodged behind the riffle bars 45 degree bars running accross the screens.

My question is I need lots of air that I can fine tune the flow rate of, the blower will be running off a 16 hp petrol motor, belt and pully, is forward facing fins on the fan the right choice and single imput air supply. the screens are 1.5 x .9 meters in size 150 mill high I plan on a center mounted hold on the screen 250 mill on bottom with louvered deflecters over the hole to spread the air around the air box, is it best to have the in and out sizes the same and is there a compromise by having a long input duct say 10 -15 meters long? Will 16 hp be too much or to little to get a lot of air throughput?

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March 26, 2019 08:56

Hi Boss I think you did well sounds almost like you have seen a dry blower working!
The points mentioned are all some help the static deposits are actually what is planned as the holes are a large sheet of sandwiched aluminium with a strong urethane inner that generates static energy, that attracts the fine gold particles, the fan you suggest is the usual way the air is distributed on a dry blower, however I was thinking the louvered deflectors may lose less energy than a fan?
the point you made about smooth surfaces and avoiding abrupt bends well taken, the heavy duty pic ducting we use does do corners ok but too sharp will kink.
The chance of clumps is greatly reduced by the type of ground we work mostly fine red dirt west Australian goldfields, it does get clumpy from moisture overnight so we have built in a substantial rotary chain crusher directly under the primary screen, this is fed by a split bucket on the loader allowing exact placement directly into the crushing zone, everything goes from -13 mill to dust.
All in all thanks mate, sometimes one needs to be told the obvious, best regards
attached is a link to another dry blowing op in nw Aus https://youtu.be/P6NwqVGRg5E

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March 29, 2019 16:49

@FlindersBiologics that looks an amazing piece of machinery and must be very robust to work in that environment! Makes my clean air environment look tame... Good luck with your developments.

March 26, 2019 08:56

This is way out of my experience where mg and ug were more common, you may need to send some samples for evaluation :)
However from my experiences which may translate in scale?
On the 'in' side of a fan you need the lowest flow resistance possible, so the shorter the duct and bigger diameter the better. You also need smooth surfaces and curves, no abrupt bends to achieve the best laminar and low resistance flow.
At the screen there is likely to be issues with areas becoming stationary/inactive, i.e. if the 'fines' clump and settle the air flow will simply increase elsewhere over the screen and not launch from the screen and probably gather more static deposits.
If you could have mutiple fans working across the screen area (even from the same inlet duct) this is likely to be better than deflectors.
Hope that may help, but hopefully someone with experience will comment.