Epoxy powder sticking 1

[rayhew]

Pls help. Epoxy coating powder keep sticking to the stainless steel silo for filling to packing bags. Kindly advise what type of remedy to be done to avoid this problem.

 

[phoward]

First thoughts are to use a coating on the SS to remove the friction of the sides. Sprays, CVD, MVD, plating, liners, etc. of slick polymers, PTFE, esters, silicones, PVC, etc. are possibilities.

But, there are many more questions to address. Is this a powder or just real small granules? Is the problem it sticks and then bridges over to where the middle will not drop? This then requires asking if you have tried vibrators, or spurge rings/air wash-stirring, what it the diameter of the silo, what is the angle of the sides, are the sides straight or do you have a spiral discharge, etc.? Can you apply, install a surface yourself or can you send the silo out for a factory install process?

 

[rayhew]

TQ Phoward. The silo is 75 deg steep 1 meter across with 8" discharge at the bottom controlled by a knife gate valve.
Powder is very fine. The silo surface is mirror finish SS.I think the main cause is static. Bridging also occur. I have used 4 vibrators and grounding but still the problem don't go away.

 

[phoward]

Static can be over come with ionized air and there are many such generator devices on the market, even with air movers to direct the stream (which could be used also in an air spurger ring sweeping air around the insides of the silo-if the powder can sustain constant air agitation).

Your sidewall angle is not an issue nor is the size of the gate, so other items come mind, how deep is the silo (is it getting packed down because of pressure from above material), what are the air moisture levels (any humidity above 35% is always a powder problem and the finer the powder, the more acute the problem), does this happen more or less at different times of the year, how long does the powder remain in the silo-filling to use-between discharges-does it happen on first workshift startup and not rest of the day?

Can the powder accept an internal lubricant-contact your supplier of this powder-your problem is not the first time for the supplier.

Mirrow finish on SS is still rough-can it be polished, can you use a silicone spray, can you line it with teflon spray and bake it on, how abrasive is the powder?

Check with your silo supplier - who picked the specs for this silo - why these specs- and then see why each was chosen or others were rejected and this can lead to a different spec.

Is this a generic chemical use of the term "epoxy" meaning oxidized in a fashion or you useing the term "epoxy" in the consumer lingo for a glue? The chemical would suggest allowing some internal lubricant, the consumer would suggest you have material binding to each other and it has nothing to do with the specs of the silo and you have to go to a different stroage design or method of delivery.

Hope this helps some more. Phillip