Dirty Business of Rubber producing and manufacturing - Page 1
Forum section: electronics / general

author: MT
author_rank: Super Contributor
timestamp: September 29, 2019, 05:39:10 pm
content: Rubber (latex) are used everywhere, tiers, seals etc, etc.Large tire piles around the planet!Satelite photos

author: coppercone2
author_rank: Super Contributor
timestamp: September 29, 2019, 08:13:13 pm
content: specifying rubber for engineering is also nasty and dirty. it gives EE headaches. need a dirty mechanical engineer for gaskets, grommets, rollers, seals, etc. (otherwise we weld it shut or pour tar on it)I feel like I am doing nascar if I need a cable gland

author: tautech
author_rank: Super Contributor
timestamp: September 29, 2019, 08:17:54 pm
content: So where have you been that you did not know about this ?Tire recycling into other products is a growing business and those that are in it are well pleased there's a good resource of raw materials.

author: MosherIV
author_rank: Super Contributor
timestamp: September 29, 2019, 09:30:48 pm
content: I think tires became a problem when we switched to radial tyres.Before the multi layer, metal reinforced modern radial tyre, tyres were recycled. You kept th inner tube and changed the tyre. The old tyre would be re-cycled.Apparently this stopped with the introduction of the inner tubeless modern radial tyre.De-constructing these radial tyres is so hard that it is not econminical to do so.It is cheaper to dump them and wait for the rubber to decompose. It takes decades for the rubber to decompose due to the black anti UV stuff that is put into the tyre during manufacture.I was wondering if there are any microbes or insects that eat rubber, so that I could start a tyre disposal company. My search came up up with nothing.

author: Stray Electron
author_rank: Super Contributor
timestamp: September 30, 2019, 12:51:07 am
content: Quote from: MosherIV on September 29, 2019, 09:30:48 pmOne of the US federal agencies looked into this years ago because they wondered where all of the rubber went when it was worn off of the tires. They said that given the amount of traffic on major roads and the wear rate of the tires that there should have been piles of rubber along the roads but there wasn't. They found that there actually was a microbe that ate tire rubber.I don't know where or WHEN that photo was taken but you never see piles of tires like that in the US any more. There used to be two giant piles near my house when I was a kid and I played on them many times but those piles and all of the others that I know of where cleaned up in the 1970s. Shredded tire rubber is used for all sorts of industrial products including new road pavement and mulch and play ground ground cover. For a while they were using old tires to make artificial reefs but I THINK they decided that they might be toxic to marine life and stopped that.OP should have done a better job with the title, the problem is with disposing of old tires, not in the production and manufacturing or rubber.

author: Stray Electron
author_rank: Super Contributor
timestamp: September 30, 2019, 01:01:59 am
content: FWIW I used to live well out into the country and I grew a lot of my own food. One of the things that I used to do was to lay a tire on the ground and fill it with soil and then plant potatoes in it. As the plants grew bigger, I'd stack another tire on top and and add more soil. By harvest time, I'd have a stack of tires 5 to 6 foot tall. I'd knock it over and it would be full of potatoes. No digging for me! The ground was hard clay and full of rocks and it was difficult to grow any root crops but using the tires made it easy.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: September 30, 2019, 01:58:21 am
content: Quote from: MosherIV on September 29, 2019, 09:30:48 pmYou're missing the fact that the bias-ply types they replaced hardly lasted 16k km. Modern t{y|i}res do over four times that; as a result, used tires have gone down by as much.No idea how much they were able to repair or replace the old ones, but I'm also guessing it wasn't too much recovered life (say 50 to 100% of original life, including multiple small repairs and one refurbishing). And the amount of labor and cost put into those repairs is gone as well -- lifetime cost of ownership is way down.As for recycling, I think they just chop them up with regular metal recycling shredders. I've seen some that rip the belts out of the carcass, which seems handy.I wonder if anyone uses induction heating for processing. Direct and deep heat into the steel cords, soften the rubber bond or melt/burn it out straightaway?Induction is certainly used in recycling (eddy current sorting, good for extracting aluminum and copper).I'm sure whatever you're looking at, the machinery starts in the six digit range. Hope you've been saving up.Tim

author: NiHaoMike
author_rank: Super Contributor
timestamp: September 30, 2019, 02:16:58 am
content: Quote from: Stray Electron on September 30, 2019, 01:01:59 amNo concerns over the chemicals used to make the tire? I gave some thought to using a worn out tire as a vibration isolator for a solar heat pump project, but I'm concerned that the tire might offgas some rather unpleasant smells in an enclosed space.

author: vk6zgo
author_rank: Super Contributor
timestamp: September 30, 2019, 02:41:46 am
content: Quote from: MosherIV on September 29, 2019, 09:30:48 pmNah!Tubeless tyres were standard many years before even fabric reinforced radials became common.Tubes were usually cheap enough that when you changed the tyre, you also fitted a new tube.It was common to retread cross ply tyres, but difficult, if not impossible with radials.A lot of uses for natural rubber have been superseded by synthetics, although the fact they come from petroleum may make them more costly, causing a return to "real"rubber.

author: Red Squirrel
author_rank: Super Contributor
timestamp: September 30, 2019, 09:52:07 am
content: Is there not a way they can be grinded down to a fine grain and used as an additive in something?

author: Electro Detective
author_rank: Super Contributor
timestamp: September 30, 2019, 11:05:41 am
content: Why stress? Rest assured the money hoarders will bring out some suppressed technology to make an easy dollar from recycling old tyres/tires when the time comes

author: jogri
author_rank: Frequent Contributor
timestamp: September 30, 2019, 11:39:04 am
content: Quote from: NiHaoMike on September 30, 2019, 02:16:58 amWell, tires consist of polybutadiene, which is rather inert and not harmfull for humans, but since they are vulcanized they also contain a bit of sulfur. Also not harmfull, although a bit smelly. But they also contain the chemicals needed for the polymerisation of the raw butadiene into rubber, and that's where you find the nasty stuff: That reaction needs a catalyst, and among of the most widely used catalysts are chromium compunds (and other heavy metal compounds). And that stuff is rather nasty, almost all chromium compounds are toxic and carcinogenic. Why is it still allowed? Because it is incorporated into the rubber and can't wash out. You only get problems when you destroy the rubber (burn it) or when it decomposes.So as long as you don't burn it it should be fine to grow some potatoes in old tires. Yes, there are a bunch of other chemicals present in a tire but those are just additives (in small amounts) and they will not dissolve in water at all (would be rather stupid if your tire changes its properties after the first rain).And for the smell: There shouldn't be any harmfull chemicals in that (otherwise your mechanic would be screwed if he is working with tires every day). If you don't want that smell, you could coat it to reduce the diffusion but how long that would work on a vibration isolator is anyone's guess.

author: voltsandjolts
author_rank: Unknown
timestamp: September 30, 2019, 11:45:36 am
content: Quote from: Red Squirrel on September 30, 2019, 09:52:07 amThat's what vehicles do, its an additive in the natural environment now

author: SparkyFX
author_rank: Frequent Contributor
timestamp: September 30, 2019, 01:57:54 pm
content: Tires usually go into concrete production, they are burnt to generate the heat for the cement to form. They burn so hot that even the steel inserts burn away, just need to add oxygen.

author: tszaboo
author_rank: Super Contributor
timestamp: September 30, 2019, 02:31:20 pm
content: Quote from: Red Squirrel on September 30, 2019, 09:52:07 amYes, that is what they do now with tires. The in the EU, 95% of tires is recycled, or used for cement production. It is increased about 2% a year, so soon to be solved.And of course the rest of the world is again decades behind, when it comes to recycling or green energy.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: September 30, 2019, 02:40:45 pm
content: Quote from: jogri on September 30, 2019, 11:39:04 amNo, this is not true -- chromium is toxic (carcinogenic) in its +6 (hexavalent) state. In +3 (e.g. commercial chromium sulfate hydrate) it's almost as non-toxic as table salt(!!).I see reference to some oddball molecules for catalysts, stuff like pentadiene carbonyl complexes, phosphines and such. It's not obvious to me how toxic these would be in the body; I think the carbonyl complexes tend to be nasty in the same way that carbon monoxide is. Think the phosphine sticks to the chromium tightly, but everything else that's attached to it, or if the molecule as a whole interferes with anything, who knows. Should be able to find toxicity on them since they're industrially important.Combusted tires of course just contain this stuff as ash in simplest form (e.g., Cr2O3), absolutely no problem.Tim

author: jogri
author_rank: Frequent Contributor
timestamp: September 30, 2019, 05:31:54 pm
content: Quote from: T3sl4co1l on September 30, 2019, 02:40:45 pmWell, i shouldn't have called it a catalyst in the first place... They are not really catalysts since they get used up, they are needed to start the reaction by breaking down and creating highly reactive butadiene species who react with other butadiene to start the polymerisation. You will get some unused chromium compounds in your final product, together with organic molecules that have heavy-metal compounds at one end.And no, Cr3+ is not harmless per se (just look at CrCl3), it just so happens that most compounds of it in that state (Cr2O3) are insoluble in water, making intoxication by swallowing it basically non-existent. Btw, chromium sulfate is used for tanning leather, i wouldn't eat it... Yes, when you burn it a good part of it will react to the oxide, but you have a bunch of organic molecules that can form interesting new compounds with the chromium, and none of those will be friendly.And as you need some highly reactive stuff to start a polymerisation, you have to use Cr6+ compounds (Phillips catalyst is one of them) or other chemicals you wouldn't want to touch (t-BuLi for example).Carbonyl groups are not toxic on their own, they are pretty tame (they are one of the essential building blocks for organic chemistry) as long as they are on organic molecules (which they are 99% of the time). CO poisoning occurs when carbon monoxide inhibits the spot of oxygen in a molecule, but since carbonyl groups are way bigger than the small CO molecule they just don't fit in that tight spot.Phosphine on the other hand is extremely toxic because it has phosphor in the -3 state and nearly every organic molecule that has a functional group will take some electrons from it (it has eight to lose per molecule, that's an insane amount). Those organic molecules change their properties/break apart and can't function in the way they should be->toxic because it may stop important processes in your body.If you dump Phosphine on chromium metal, nothing particulary bad should happen but if you dump it on chromium that has a higher oxidation state, it will explode (and maybe form some phosphor-chromium compounds in the process).

author: T3sl4co1l
author_rank: Super Contributor
timestamp: September 30, 2019, 05:54:14 pm
content: Quote from: jogri on September 30, 2019, 05:31:54 pmFortunately most of the organic molecules are various permutations of butadiene and relatives, so they all burn up however they do. A nice hot tire fire doesn't release any organic pollutants, beyond the usual CO2.I looked up CrCl3:https://www.cdc.gov/niosh/idlh/cr3m3.htmlLooks pretty harmless to me.Not that I would want to taste-test an ounce of the stuff... but I can't say I'd want to taste-test an ounce of salt all at once, either!QuoteWell, the glance I took, didn't show any Cr(VI), but that would be one. It would obviously be reduced by combustion. Stuff like t-BuLi isn't even stable in air, so I don't see how you could come into contact with that from used tires.QuoteYeah, that's why I said a metal-carbonyl species?QuoteAgain, phosphine complexed to chromium already. Not straight up PH3. I don't get where you're misreading these things.Anyway, these pertain to manufacture, and it's probably not anything of significance for the finished product.Tim

author: MT
author_rank: Super Contributor
timestamp: September 30, 2019, 06:08:42 pm
content: Quote from: Stray Electron on September 30, 2019, 12:51:07 amOP did a very good job of posting a video about the problem of latex industry, sadly you didnt have the spinal strength to watch it.Quote from: Red Squirrel on September 30, 2019, 09:52:07 amPeople have been looking into used tyres/tires for manufacturing graphene.Quote from: tautech on September 29, 2019, 08:17:54 pmIm just reminding you old demented folks of your past sins!..in 2012 a mine dump truck tire was 42500USD!https://www.businessinsider.com/this-is-what-a-42500-tire-looks-like-the-5980r63-xdr-2012-5?r=US&IR=T

author: jogri
author_rank: Frequent Contributor
timestamp: September 30, 2019, 06:52:10 pm
content: Quote from: T3sl4co1l on September 30, 2019, 05:54:14 pmI didn't intentially misread those things, i just thought you referred to those substances and not their complexes with chromium (because you could probably start polymerisations with pentadiene sandwiches or phosphine alone). Sorry for that.Quote from: T3sl4co1l on September 30, 2019, 02:40:45 pmAnd yes, you won't find any trace of BuLis in your rubber, i just used it as an example of another chemical you could use for starting a polymerisation.About the toxicity of Cr3+: Seems like the german compound databases are a lot more cautious than the CDC, they say something along the lines of "we don't know for certain if it's toxic, but it has shown some chronic toxicity in some patients".And sure, if you have a nice hot fire with enough airflow you can burn tires without a problem, but if you just light one on fire it will smoke quite a bit. And the presence of black smoke (carbon dust) tells you that the fire doesn't get nearly enough oxygen for a complete combustion, and chances are that your chromium won't get enough oxygen to form Cr2O3.Btw, i just remembered one other group of Cr6+ complexes that will not get used up in the polymerisation: Fischer carbenes. But since no one uses them anymore you won't find them outside a lab.

author: LeonR
author_rank: Regular Contributor
timestamp: September 30, 2019, 08:43:27 pm
content: Tire recycling (at least the rubber part of it) for asphalt seems a good solution, although there's a rather lenghty (and probably expensive) processing needed:

author: jogri
author_rank: Frequent Contributor
timestamp: September 30, 2019, 09:44:35 pm
content: That process is without a doubt expensive as hell, as rubber has a rather low thermal conductivity and therefore needs more time to cool down to cryogenic temperatures, decreasing the throughput and increasing the cost.Since that got me interested in how much energy you need to get rubber to 70K, i decided to get a rough estimate (if you find errors, please correct me).Rubber has a heat capacity of around 2 kJ/kg*K, and lets say we have to drop its temperature down 220K (starting at 300K and going down to LN2 temperatures). That makes 440 kJ/kg of rubber.LN2 releases around 200 kJ/kg when it evaporates and has a specific heat of around 1 kJ/kg*K. So we need 200+220kJ to get liquid nitrogen to room temperature. Close enough to the 440kJ needed to cool down one kg of rubber, so lets say it's 1:1.Seems i was wrong, it costs only around 10 cents to cool rubber to that temperatures (if the rubber is the only heatsource for the LN2). 1-2 bucks per tire doesn't seem that much, but when the price for "normal" recycling is around 75€/ton (here in germany) there is no way you can make money.It would also be interesting to know if you can recycle that rubberized asphalt like normal asphalt...

author: T3sl4co1l
author_rank: Super Contributor
timestamp: September 30, 2019, 09:49:10 pm
content: Hm, I wonder how much rubber's Cp drops as it cools down. (Basically, the heat capacity of materials generally goes to zero as temperature goes to zero. Since, there's simply few modes available to store heat in, when the energy level is so low. Good news when you're trying to cool something down, it stops taking much heat; bad news is, you have to work so damn much harder to get there, because all your fluids suck, too!)Add to that, you can recycle some cold with a cross-flow heat exchanger -- as the cold crushified bits come out one tunnel, the cold air is blown over the warm stuff coming in another tunnel. That probably accounts for a potential 50-80% operating savings?So that's not bad, and considering LN2 isn't terribly expensive to buy or make.Tim

author: jogri
author_rank: Frequent Contributor
timestamp: September 30, 2019, 10:30:46 pm
content: I'd take the guess that the cp of rubber drops faster than that of N2 because a polymer just doesn't have that many ways to vibrate (no rotation around its axis). I don't think that a heat exchanger will give you a significant energy reduction when you use just rubber as it has a poor thermal conductivity and it is solid, therefore it doesn't get the benefit of convection currents. A LN2/isopentane cold bath could work though as it still gets to 113K with the benefit of having a suspension that you can pump through a heat exchanger. Also, isopentane boils off at around 300K. The question is if having a better heat exchanger justifies the energy penalty from cooling down the isopentane.

author: Stray Electron
author_rank: Super Contributor
timestamp: October 01, 2019, 06:26:31 pm
content: Quote from: MT on September 30, 2019, 06:08:42 pmDon't worry I have the strength to watch it, just not the patience! Your title says latex but the pictures that you show are tires made of Butadiene rubber, not Latex. The pictures that you show are related to disposal of tires and have nothing to do with the creation of Latex rubber products. Finally you state that waste tires are piling up all over the planet when again. you're completely wrong and that every developed country has been safely disposing of them for at least four decades.In short you really don't seem to know what the hell you're talking about! The don't know the difference between latex (which hasn't been used to make tires since the 1940s) and Butadiene rubber and you haven't figured out if you want to complain about the problems of manufacturing or of disposal and you haven't bothered to do any basic research because if you had then you would have known that most, if not all, of the problems were dealt with years ago.