Buchner filter funnel filter membrane
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You buy filters in different sizes.
Most of our work can be done with "coffee filters", but sometimes we need better filtering.
More important then is big area filters and fiberglass under for better filtering.
And other times we use the same coarse filters to let them "saturate" to filter good enough.
What operations do you plan to do?
I’m going to attempt the aqua regia method sometime this year. I’m writing down my questions as I read the c.m hoke book and that’s one I couldn’t seem to find the answer to.
My number one go to filters are a Whatman #1. Other brands can be or are just as good but I already have a nice bunch of these on hand. I use them primarily for final filtering of AR as they can catch some very fine particles. I have used commercial grade restaurant filters made for tea, and often do most bulk filtering with them, again I stick with them because I can get them easily and free from a couple of local restaurants. Coffee filters are always on hand and great for coarse filtering, by running the solutions through multiply times they will stop up some and catch more and more finer particles as well.
Just think of how many coffee grounds end up in the bottom of your cup with a standard catering filter paper.
Considering gold is £57 a gram and can be in some very small particles during recovery imaging, how fast an inadequate filter paper loss of value will outstrip your savings on cost.
In refinement, you are trying to produce the cleanest and clearest solution to drop your value from. Again, a catering filter paper is by necessity more of a colander, suitable for retarding the moment of large organic fibers.
Rather than a dependable filter paper fine enough to remove AgCl but robust enough to be acid-resistant yet stout enough to survive a strong vacuum.
Don't skimp on your kit, it is a false economy.
Considering gold is £57 a gram and can be in some very small particles during recovery imaging, how fast an inadequate filter paper loss of value will outstrip your savings on cost.
In refinement, you are trying to produce the cleanest and clearest solution to drop your value from. Again, a catering filter paper is by necessity more of a colander, suitable for retarding the moment of large organic fibers.
Rather than a dependable filter paper fine enough to remove AgCl but robust enough to be acid-resistant yet stout enough to survive a strong vacuum.
Don't skimp on your kit, it is a false economy.
Very nice explanation of particle size in reference link:
In general as stated above a Whatman #1 I believe is the goto.
Note: many instances you need to run the filtrate solution through paper more than once and upto 2 or 3 times may be needed. Appears Whatman 1 11um, in order for clear filtration 2-3 times same filter paper.
Check Sreetips videos on youtube, 1 of my favorites.
Nice reference here. (CLICK GRF POST)
Whatman example of paper:
In general as stated above a Whatman #1 I believe is the goto.
Note: many instances you need to run the filtrate solution through paper more than once and upto 2 or 3 times may be needed. Appears Whatman 1 11um, in order for clear filtration 2-3 times same filter paper.
Check Sreetips videos on youtube, 1 of my favorites.
Nice reference here. (CLICK GRF POST)
Whatman example of paper:
Last edited:
That was the reason for asking about his process.
For filtering pregnant solution the target is mainly to remove anything causing turbidity or even a bit of metastannic acid.
Then there is not that important what you use.
If you are filtering anything that can contain solid values the picture changes.
Yes, there is a small sweet spot for filtering fine particles.
You may need to run some fluid through to reduce the size of particles that are trapped, and then start filtering again.
But fine particles will eventually completely block your paper permanently.
You will get a slightly higher effective run-time from the correct paper that does not depend on premature blocking of the hole to function effectively.
But if your filters are blocking regularly, you may wish to invest in a larger surface area to work with.
That soon gets quite expensive.
https://www.coleparmer.co.uk/p/cole-parmer-plastic-buchner-funnels/3998
anachronism
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Whatman 1 for me. Occasionally 4. With the correct setup 1 pass will be fine. Especially if it's a recovery drop as opposed to a refine.
Edit: You should be able to read a newspaper through the solution.
Edit: You should be able to read a newspaper through the solution.
anachronism
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- May 31, 2016
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Oh and this is an absolutely essential part of any pump based filter setup.
Spend the money and save yourself tonnes more in time and effort.
Spend the money and save yourself tonnes more in time and effort.
I'm a newb...but here's a tip that I use a lot. I have a 70 mm buchner so I preform the oversized filter papers around the outside of a 250 ml beaker and use it to push the filter down into the buchner funnel....then saturate the filter with distilled water before filtering fluids.
