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Chemicals for silicates (10 replies and 5 comments)
Dear Robert, thank you for your reply. I forgot to mention that, it's asbestos, mainly chrysotile.
Thank you a lot
I think that you could try using a light amount of pine oil frother or try one of the other frothers without moderating the pH initially. The fibrous silicates (chrysotile) may coat more effectively than the other silicates. Try scant dosages initially, otherwise if you coat the sands also, all will float. You have not mentioned your natural pH of the slurry. However, going slightly basic with some caustic might improve the separation with pine oil or other oily frother. Try natural pH first.
Richard
Dear Richard,
thank you for your kind reply. I will start with pine oil then. pH is slightly acidic but I was already thinking to neutralize it .
Regarding the chemicals, can you suggest any companies or websites specialized in them? Since I come from chemistry field, I always bought chemicals from Sigma Aldrich, but those kind of reagents are not in their catalogue.
Again, thank you so much.
Lead zinc flotation sometimes uses pine oil so you might check mining chemical suppliers. A google search for suppliers might be useful also. You don't need analytically pure reagent for use. I picked a neutral to slightly basic pH so that it would not favor the flotation of the silica sand, hoping that the fibers might respond differentially with a frother only. Sodium silicate can be used as a dispersant for the fibers if the frother alone doesn't work or another dispersant.
Marco, I don't think you are going to find affordable industrial chemicals fromm Sigma-Aldrich the usual handul of 'fine chemical' manufacturers. You need to find a supplier of bulk industrial chemicals. Likely as not, there will be proprietary names for their products and you willl need to 'translate' your generic names into their lingo. That may take some effort, though online search engines should help. There are many of these that point to manufacturers based on keys such as chemical, generic and proprietary names you provide. I can't think of any right now, but they can be found with a bit of searching.
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Marco, If you are floating sand from fibrous silicates, you are really floating silica away from silicates. the floation of silica is usually done at very low pH (2) and you use petroleum sulfonates to float the silica. The problem you have here is that the fibrous silicates will cause rheology problems in the pulp. So you will need to add a dispersant like polyphosphate or acrylate type.to get the dispersion you need. Or you can use very low solids. Some people have had success with breaking up the fibers using by preconditioning in very acidic solutions under high shear. There are lots of papers describing industrial sand flotation for your conditioning and you should look up papers on the treatment of ultra mafic ores that usually contain lots of fibrous minerals. this will help you in picking the dispersion scheme you need.
Marco
This is an interesting combination of materials.
A good source of information on the flotation process is the 'Mining Chemicals Handbook':
https://www.911metallurgist.com/wp-content/uploads/2017/03/2002-cytec-mining-handbook924751.pdf
What is the approximate fraction of silica and chrysotile?
Separation is often easier when you float the smaller amount of material in the ore/feed.
Chrysotile is reported to have a high ZPC of approx. 11
Silica has a low ZPC of approx. 2.0-2.5.
These respective ZPCs should permit using a cationic collector to float the silica at natural pH or an anionic collector to float the chrysotile at natural pH. This is why comparative amount of each is an important factor.
Collector types are discussed in the referenced Cytec Handbook.
Other considerations re chemicals and operating conditions are also covered.
Are there any other minerals present?
Dear all,
my initial idea was to float the chrysotile and keep the sand in the underflow. General composition is 30% chrysotile and 70 % sand, no other minerals are presents (if not as a small impurity). What do you think a good anionic collector would be? (at least for the first stage of tests).
Thank you all a lot.
With 30:70 split floating the chrysotile seems good starting point.
Sodium oleate is good starting point. It is less aggressive than the sulphonates. You can optimize collector after doing some exploratory flotation tests.
Sodium oleate has frothing characteristics. Depending on dosage you may not need supplemental frother.
What is particle size distribution of this material?
It is mainly centered on 3/400 micron. Size distrubution of fibers actually its unkown (I actually have no idea on how to determine it in a reliable way), it is likely to be quite a broad distribution of sizes, from few micron to hundreds.
Thank you
Dear all,
thank you for your help. I am now waiting for the chemicals to arrive and start the experiments. I'll let you know soon how it is going.
Thank you a lot again
Dear all,
I'm about to start to conduct some experiments on froth flotation to separate some fibrous silicates form sand (which is still silicates sadly). SInce I have no experience with this technique I would like to ask you which could be a good combination of frothers/collectors/depressants? Or at least a good starting point.
Thanks all!