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Author: Subject: Grinding/powdering glass in a blender - with water in blender?
RogueRose
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[*] posted on 1-3-2019 at 08:40
Grinding/powdering glass in a blender - with water in blender?


I need to make some glass frit and I've found it is MUCH more difficult than i thought it would be. I have a "pestle" I made from a 1 cup stainless steel measuring cup that I filled with lead and placed a 30" 3/4" piece of rebar into the lead. There are also 3 5/8" bolts going into the sides of the pestle that were used to center the rebar before the lead was poured to fill the cup. This works great for a lot of things and I've tried to use it with broken pieces of lab glassware (all borosilicate) and have all the glass broken up to max size of about 1/4" max size in any direction.

I use an old soup can which the SS cup fit's inside to hold the glass (with just enough water so there is no dust) and then smash the glass with an up and down force and a little rotational grinding. Even though I used a wire wheel to remove any rust from the exterior bolt heads, it seems that there is a fair amount of rust getting into the glass powder (it looks sand colored, you would think it WAS sand). I run the smashed glass through some strainers/sifters with decreasing size ending with a plastic (LDPE??) coffee filter mesh, which still allows a fair amount to pass through. The finest parts are the ones that looked sand colored, the rest have been washed with clean water (and a little HCl + H2O2 - which give crystal clear glass)..

I was wondering if i could use an old blender (ti is very thick glass to grind up the larger pieces of glass that remain. I'm only about 10% done with all the glass after about 2 hours.

I figured that I would add water with the glass pieces, that way it should keep the glass down towards the bottom instead of on the sides. There are different speed settings, pulses etc. I'm open to sharpening the blades as they are currently rounded a little bit (from wear or came that way..?) and trying different settings.

I'm just worried about something building up at the bottom and causing the blades to lock up and stripping the coupling gear on the base of the blender. This happened with aluminum when I tried grinding some (not even a whole lot - it was a different blender, a much more expensive one... it was dry & maybe it caused the Al to melt in that case??)

The only other option would be to use a coffee grinder, though I don't have any decent ones ATM and IDK if they can be used with a little water to keep the nasty dust down.

I guess a ball mill could be used, IF I has a working one, but ATM I don't - I really need to get one up and running.



blender.jpg - 20kB
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Sulaiman
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[*] posted on 1-3-2019 at 08:59


On the Mohs scale of hardness, lead = 1.5, glass = 5.5 https://en.wikipedia.org/wiki/Mohs_scale_of_mineral_hardness
so lead is a poor choice as a pestle for crushing glass.

Put the glass in a cloth bag on a rock and smash with a hammer ?




CAUTION : Hobby Chemist, not Professional or even Amateur
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RogueRose
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[*] posted on 1-3-2019 at 10:07


Quote: Originally posted by Sulaiman  
On the Mohs scale of hardness, lead = 1.5, glass = 5.5 https://en.wikipedia.org/wiki/Mohs_scale_of_mineral_hardness
so lead is a poor choice as a pestle for crushing glass.

Put the glass in a cloth bag on a rock and smash with a hammer ?


The lead was melted and poured inside of the stainless cup (lf 1 cup in size - about 220ml or so??), so the outer side of the pestle is stainless steel. It handles the glass pretty well, only very slight scratches. I tried this with a brass mortar and pestle (for only a couple "poundings) and stopped b/c it was causing damage).

As far as the cloth bag, the glass would shred the bag very quickly.

In addition, the can I use to hold the glass is a steel (tinned I think) soup can, and it has held up remarkably well with all the pounding it took.
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Gearhead_Shem_Tov
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[*] posted on 1-3-2019 at 17:45


The "standard" way of doing this is to use black iron plumbing pipe nipple with a cap screwed on the bottom. Put your glass shards in, then use a steel bar a touch smaller diameter than the inside diameter of the nipple and pound away.

Screen the finer particles out, resume pounding the larger ones, etc.
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RogueRose
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[*] posted on 1-3-2019 at 19:57


Well, "It will blend!!!" I got a cheap $2.99 blender (which was interchangable with a nice Sears base/motor), but the cheap one had a polycarbonate "blending vessel (can't think of name)



Strange, I couldn't add any pics except one at a time (had to edit the post and add another image once the first one was posted).

The next 3 are just pictures of the 8lb pestle I made from a stainless steel measuring cup into which I poured hot lead - there are standard steel bolts on the side, which rust. I think I need to cut those off to give more room for clearance. This works REALLY well when breaking up crystals/powders, things that seem like they are rock hard, this does a great job!

01 Pestle 2 with rebar and bolts.jpg - 326kB


02 Pestle.jpg - 332kB


03 pestle and can.jpg - 271kB

This is what the glass looked like after using the pestele - I think it was from the rust from the bolts on the sides and in the can
04 sandy look.jpg - 116kB


05 sandy look 2.jpg - 130kB

This is the sifted glass (through tea and or coffee filter) after it has soaked in a little HCl and H2O2 (35%)

06 acic & h2o2 washed.jpg - 295kB

07 3 jars side.jpg - 301kB


08 3 jars.jpg - 259kB

09 blended glass.jpg - 393kB

10 glass ground in blender - grey.jpg - 237kB

11 straight from blender.jpg - 338kB

[Edited on 3-2-2019 by RogueRose]

[Edited on 3-2-2019 by RogueRose]
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crystal grower
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[*] posted on 1-3-2019 at 22:40


You can make very fine SiO2 powder by mixing liquid glass and H2SO4

[Edited on 2-3-2019 by crystal grower]

IMG_20190302_075401.jpg - 1.3MB




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RogueRose
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[*] posted on 1-3-2019 at 23:41


Quote: Originally posted by crystal grower  
You can make very fine SiO2 powder by mixing liquid glass and H2SO4

[Edited on 2-3-2019 by crystal grower]


Thanks for the tip! Is that sodium metasillicate or sodium sillicate? I actually came across a gallon of some of the metasillicate (it's VERY heavy). I kind of wish I knew that before, but I'm wondering if the SiO2 from that method wouldn't make too pure a compound because it is essentially quartz (pure SiO2) which has a much higher MP than soda lime glass and even borosillicate.
I'm not sure I could get the pure SiO2 to reach the glass transition point, where borosillicate looks to be around 1200-1250F and SiO2 is about 400-500F higher IIRC.

As far as the colors of my ground glass, the grey is from the metal blade wearing away and the HCl + H2O2 has cleaned it up beautifully, just as it has the brown, sand looking glass. I'm not done processing it yet but I'll post some pics when I'm done.

I was really surprised when the cheapo Proctor Silex blender chopped up the glass. The pieces weren't too big, I had smashed them a little with that pestle so there weren't any pieces longer than 1/2" (and they were thin like beakers). I'm wondering how much harder the glass is to ice b/c it really sounded like I was making a daiquiri, lol :)

I was thinking of using the metasillicate as a binder with some clays and maybe some CaO or Ca(OH)2 & some sand to make a refractory for a kiln or forge. IDK if it is worth it to use the metasillicate in place of water, but it supposedly increases the temperature handling of the material.
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crystal grower
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[*] posted on 2-3-2019 at 00:39


I think it's the metasilicate but it shouldnt really matter.
I don't remember exactly how I did the experiment but anyway, after mixing the water glass and sulfuric acid, you get a gel-like precipitate of silicic acid which needs to be dehydrated using heat. Make sure to keep stirring it during the whole process.
I won't help you with the glass transition point, you'll have to try it yourself.

I'm also suprised the blender did such a good job, can the blades be even considered as blades anymore?:D




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RogueRose
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[*] posted on 2-3-2019 at 01:03


Quote: Originally posted by crystal grower  
I think it's the metasilicate but it shouldnt really matter.
I don't remember exactly how I did the experiment but anyway, after mixing the water glass and sulfuric acid, you get a gel-like precipitate of silicic acid which needs to be dehydrated using heat. Make sure to keep stirring it during the whole process.
I won't help you with the glass transition point, you'll have to try it yourself.

I'm also suprised the blender did such a good job, can the blades be even considered as blades anymore?:D


Yeah, they are still in pretty good shape. I'd guess they lost about 1-2% of their surface tip. The edges got a little dulled. I'll take a pic and post b/c I was pretty impressed as well. I can't believe this worked and when I tried Al foil of loosely balled foil and about 1/5 - 1/4th full in the blender. IT was a really expensive Kitchen Aid ($200+) blender and it destroyed the coupling 4 times and I couldn't grind anything with it. I'd try to do it again but I'm afraid it will break it again.
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[*] posted on 2-3-2019 at 03:25


Its simperler and probably cheaper to buy silica gel as cat litter than make it.

The silica gel is very friable so it quickly (compared to glass) blends to a fine powder with a significant air float fraction.

I would guess that blending in water reduces the grinding efficiency of turning the small particles to finer ones.

The powdered silica gel can also be used to make a sodium silicate solution as it readily dissolves exothermically in sodium hydroxide solution.




i am wg48 but not on my usual pc hence the temp handle.
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[*] posted on 5-3-2019 at 09:34


There are also some cleaning/polishing products out there that are labeled as the only ingredient is quartz powder. I picked some up in the clearance section at the grocery store for 50 cents/ bottle the other day. I will take a pic when I get home and post it for the product details.
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