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separating carbide dust from oil

04/22/2009 11:30 AM

I have just recently started to reclaim solids from paper type cartridge oil filters. I am reclaiming fine carbide dust which results from our grinding of carbide. Our manufacturing process filters the cutting oil/carbide through the paper cartridge via pump, and,when back pressure exceeds a preset limit, we change the filters.

I have been accumulating the spent filters and now wish to recover the carbide. I have so far successfully removed the carbide/oil mix from the filter, and perhaps 95 percent of the oil and now wish to separate the remaining oil from the carbide.

The oil is pure synthetic and of similar viscosity to that of engine oil. I am typically removing 12 lbs of carbide per filter, and so far been separating by mixing with varsol, letting the mix settle, skim off top varsol, and repeating this mix-settle-skim process till most of the liquid is gone. I then leave the mixture in a shallow pan to vent/flash off remaining solvent to atmosphere.

question:-

Is there an easier way to separate the mixture?

Is there a better solvent other than varsol to create the separation?

Any other suggestions are most welcome

thanks

Jim...

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#1

Re: separating carbide dust from oil

04/22/2009 11:37 AM

If both components, being the carbide and the oil, are needed for re-use, then, no, there isn't a better way to do it apart from increasing the separating force, which is so often gravity, using some form of centrifugal action.

If the carbide is to be, ahem, "recycled to the environment" then it might be worth looking at cartridge filters, and pumping the carbide/oil mixture through them to speed things up. It would also reduce the oil inventory hanging around; if the oil evaporates then it might present either a health or a flammability hazard that is better avoided.

What sort of quantities are involved, and what is the flashpoint of the evaporating material?

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Associate

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#2
In reply to #1

Re: separating carbide dust from oil

04/22/2009 12:35 PM

We currently collect in a paper cartridge filter. When I change the filter, the filters (in pairs) are left to drain for a couple of days, then I cut off both ends, remove the steel mesh, open up the paper concertina and scrape the 95% solid mix into pans for the mix-settle-skim process. This is not a commercial operation and takes perhaps 1/2 man hour to complete (except idle time between settlement). In all I will do about 20 pieces at a time.

I was hoping someone else could advise on flash point. the oil I think is relatively high it is used in a grinding process, don't know about varsol. All the oil is fully recycled and the carbide, when seperated is sold as a high value 100% reusable scrap product.

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Guru

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#3
In reply to #2

Re: separating carbide dust from oil

04/22/2009 10:26 PM

Did you try other types of filtering ? say Electrostatic or centrifuge ?

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#4

Re: separating carbide dust from oil

04/22/2009 11:02 PM

If it is in fact carbide dust and there is only minor oil traces, then what about "compression" of the sludge?

Sufficient pressure should force the oil out of the powder "sponge" leaving you with minute traces of oil.

I've seen devices used for recovery of machineing fliuds from swarf and surely a similar device could be used for this application.

Also, th ecarbide processor may not object to the small residual oil since this may be removed naturally by their own processing steps.

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#5

Re: separating carbide dust from oil

04/23/2009 2:54 AM

Off the cuff.

Perhaps consider extreme dilution and precipitation then oil and solvent recovery by distillation. To make distillation simple and cheaper use petrol (gasoline) or other low boiling aliphatic hydrocarbon (dry cleaning benzine to some - benzine NOT BENZENE! - pentane or hexane) the lower boiling point will lower the distillation temperature.

The possibility of centrifuging the oil and solvent mix before distillation could help. The SG difference between the diluted oil and the solids would increase

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#6
In reply to #5

Re: separating carbide dust from oil

04/23/2009 6:29 AM

Hello,

Your suggestion of using Hexane etc is an expensive proposition. I used large volumes of Hexane to remove paraffin oil from skived UHMW ribbon. It is very effective in driving out the paraffin oil but dealing with the mix of hexane and paraffin went like this. We made a still and drove off the hexane from the paraffin into a condensing unit and recover both solvents.

We are allowed 6ppm of Hexane in air. (not even a whiff), in California. The lower explosion limit of hexane in air demands either a sealed system or large volumes of air to dilute the air to below the explosion limit. That air must then go through activated charcoal to remove the solvent. Remember 22% oxygen in air. Hexane is non electro conductive and therefore must be grounded at all times.

Moving an ungrounded barrel can build up a static charge and lead to an explosion if you are statically charged or any instrument you have causes a static spark. Last but not least the flashpoint of Hexane is ~-64 degrees. Hope this helps.

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#7

Re: separating carbide dust from oil

04/23/2009 10:40 AM

Try to add a small amount of your synthetic oil to the carbide suspension you collect from your filters to reduce the viscosity of the suspension. If the viscosity is not low enough, you can use low viscosity oil instead, like mineral oil.

Then mix it with water and let it settle. The oil will stay on top and the carbide will go to the bottom. You can also use centrifugation to accelerate the settling. Remove the floating oil and the excess of water and let dry the carbide dust in air. You can use an oven if you want to accelerate the drying. You might also be able to recuperate and dry the floating oil to use it again to dilute other filtered carbide suspension.

Let me know if this work.

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