CRT again

Hi, your English was pretty good. I recall, from the days when I worked around CRTs, that they are painted on the outside with lead. So, I think that concern involves the lead on the glass more than the lead in the glass.

I am very glad that the industry has largely switched over to LCD screens. That transition is eliminating three potentially harmful things: ionizing radiation emission, high voltage, and lead pollution. LCDs take up much less space, too.

Thank you,

This is something that I can add to long life book.

Yes LCD is now the best solution.

Hubert

Thanks, too. I commend you for your planning to reclaim the materials from old CRTs.

Pardon my ignorance. But, what is a CRT?

That abbreviation stands for cathode ray tube.

I've been stumped! All those years it never occurred to me that the soft, dark coating that looked like metal wasn't lead. Now that it is mentioned, lead ought to have looked grayer than the coatings were. Graphite is very soft like lead, but is also darker in color, which escaped my notice.

USBPORT has it right, CRT technology is much the same as we still use to manufacture image intensifiers, the phosphors are deposited on to optics then coated with aluminium to provide a conductive path. Aquadag is used to prevent surfaces charging up with the high voltages used by the electron guns.

Our company is not allowed to let the phosphors get into the local drains as they are classed as poisons.

Good day Nigh,

Can you tell me what you do with the phosphors?

Are you in the recovery business?

It is nice to read your comments.

Hubert

"The metal lead in the glass is not really dangerous because we love to drink wine in a Crystal coupe and we never heard somebody died of lead poisoning and humans did this for hundred of years."

Hubert, the lead in lead glass is not in the form of a metal, but as poisonous lead oxide. This oxide is pretty well tied up in the glass chemistry and not available to cause harm. However, under certain conditions it can be leached from the glass matrix and cause harm to humans. Long term storage of certain beverages in leaded glass decanters has poisoned people. I'm sure that if you check web sites, you can find links to this concern.

GA to welderman and Usport.

I have a very good friend who runs a few labs (Caduceon) in Ontario. He was telling me over a glass of wine to never drink from lead crystal wine glasses. He had preformed some leach tests on a series of different wine glasses and found a 24 hour leach averaging 600 μg/L. The allowable content in drinking water is 15 μg/L with an objective of zero. I have spent a long time investigating natural lead in drinking water and follow the rationale for eliminating lead in water. Although we don't seem to record lead poisoning from wine glasses, we do have records of Gout caused by lead crystal. I for one, will not use lead crystal glass for any purpose involving consumption.

Just sell off all those pretty and expensive wine glasses and forget using them forever. "Get the lead out", now has another meaning.

Crystal glass are high lead oxide and is well documented lead oxide is slow poison and will eventually effect you.

Lead oxide is released slow from human body and the effect is as it starts concentrating in body as poisons lead oxide. Glass does not contain metallic lead but lead oxide to provide the beauty but that beauty comes with beast which is Poisson

CRT funnel glass does not contain any lead but lead is present in

1. between front viewing glass and cone

2. All capacitor used inside the cone is have termination which is based on leaded solder materials

3. All mother board lines are based on silver or lead

In total there is about 1.0 to 10 grams of lead in a typical old CRT based on size. This lead will be leached out by rain water. Leaching will depend how acidic rain water it and is the main reason every sensible government agency is banding CRT based TV from controlled dump

Tundra242,

Can you give me more precisions:

When you mentioned "Etching with a hot (~120°F ) nitric acid" do you have an idea of the % of nitric acid?

Not being fully bilingual, can you tell me what is "HL or amonium bi fluoride" and their concentration in percentage?

Thank you for your help. Your article is very usefull.

Hubert

I am going off of memory, but I believe it was 6% nitric. The etching takes a long time , 10 min I believe. That was also to separate the parts for reuse into CRT production without breaking the glass, it you are just separating components for disposal you may get away with a higher concentration and less time.

I think the HF was 5-8% from memory. ABF is slightly safer. HF is nasty, make sure you follow safety precautions.

I know some companies also used Oakite, I cant remember which compound. It was an Oakite ##, http://www.chemetallamericas.com/products/by_app/cleanersSanitizers/cleaners_O.aspx

I think it was KOH with some surfactants in it.

Obviousl, none of these compunds reduce the hazard. Go from a large solid waste to a lot of liquid hazardous waste. So this leaves liquid hazardous waste that must be treated now.

Except for the fact that you can wash out few ounces of contamination and re-use the glass, as was our intended purpose. Some companies also precipitated the lead out of the acid and sold it to battery makers, preventing it from entering the water stream.

Exactly, additional treatment stages. though the recovery of the Glass would be a good benefit if the Glass did not have to be reformed/recast. The Acids themselves would comprise hazardous wastes that would need to be recovered or diposed of. I hope they weren't disposing of them in the natural waters. Though admittedly, it does appear easier for industries to disappear drums of liquid waste then solid wastes.

No releases into the wild, full water treatment plant on site, ISO14001.

Water treatment plant means more hazardous waste generated in a concentrated form. Eventually it all has to go somewhere or be recycled.

HF is Hydrofluoric acid. Really nasty stuff.

Beyond Pb, BaO and SrO are the meanest toxins in CRTs. Green and Red fireworks if you will.

http://en.wikipedia.org/wiki/Barium_oxide

http://en.wikipedia.org/wiki/Strontium_oxide

Search for Material Safety Data Sheets (MSDS) and I would hire a chemist before trying to dissolve anything out of a monitor.

Coldspot-- While I agree with you that in the future the landfill will be mined as a rescource, I suggest you read up on how and how many CRT monitors were made in last 3 decades. E-waste is a very real problem that industry is not going to solve without someone doing some pushing and shoving.