evfreek

Can recycled tires be used as fuel?

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Hi. A friend of mine took me to a construction dump and showed me a huge pile of waste tire rubber. It came from an elementary school playground mat that was made from shredded old tires. The mat was perforated into sections about the size of charcoal briquettes (2x2"), and it was falling apart into blocks. He showed me a block closely, and it appeared to be made out of a network of rubber shreds. Then, he asked me why he brought me there. The little light bulb went on, and I said "forge fuel"! But, tires burn dirty with billowing black smoke. Then, he asked me, doesn't coal also burn dirty.

I realized that burning tires can be quite an emotional issue, especially with the "Johannesburg necklace" and all that, but it was interesting to see the hard facts behind the scenes. If one surfs the web for awhile on this, there are a lot of hits. Many of them are emotional, non-technical, and not very well grounded appeals to deny approval to a tire incineration project. But, there are a lot of technical documents from the EPA and various state DEQ's. So, the bottom line is that tires are primarily a low grade hydrocarbon, with slightly less greenhouse gas potential than straight carbon. They are potential generators of dioxins upon combustion due to tiny amounts of chloride, but coal contains about the same amount of chloride, and therefore has the same potential. They have about the same heavy metal content, except for zinc, which is much higher. The shredded tire chunks in the playground waste pile seem to have the steel wires removed, which would greatly reduce the zinc content. Tests done on incinerator stacks show about equivalent levels of emissions, even within each class, as compared to coal or coke. Temperatures of combustion are similar in a well aerated fire (3000-4000F). There is no billowing black smoke.

I went to an environmental workshop, and it seems that coal is pretty dirty only in that it generates emissions which get concentrated in the food chain. So, coal is a major source of mercury emissions, but blacksmiths do not get mercury poisoning. Consumers of the "big 5" near coal fired electrical generation facilities get it :(

Could these briquettes be a possible forge fuel? Has anybody used it successfully?

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Trace elements are defined as elements present in coal in amounts of less than 1 percent by weight. Generally, trace elements are present in coal in amounts much lower 1 percent, and are reported in parts-per-million (ppm) by weight in the coal. A trace element concentration of 1 ppm = 0.0001% by weight, or expressed in another way, a 1 ppm concentration of a trace element equals one pound in one million pounds (500 tons) of coal. Most trace elements in West Virginia coals are present at levels of 10 to 100 ppm, or less.




Highly toxic elements (e.g. arsenic, mercury, lead, and selenium) are present in West Virginia coals, though generally in very low concentrations. How hazardous elements present in very low amounts adversely impact the environment is a matter of scale. For example, a coal fired power plant with no pollution controls in place theoretically would produce 10 tons of lead for each million tons of coal burned containing 10 ppm lead. However, modern pollution control measures provide controls against the release of large amounts of hazardous trace elements to the environment.



Reference BP0051 Good Coal


It may take a while to burn a million pounds of coal. (grin)

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While throwing green coal on top of a coal fire will cause a lot of smoke, a well maintained coal fire has very little smoke. In a well maintained fire the coal is added to the outside of the coal fire and over time graduates towards the center. Meanwhile the volatiles burn off and by the time the coal reaches the center, the fire tends to have very little visible smoke. The spread of the fire and coking process is also controlled by application of water.

I may be wrong but I don't think that you would be able to burn off the volatiles and visible smoke in a pile of rubber-like substance in a similar manner.

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How high is the sulfur content in the recycled tires. I remember that rubber is vulcanized using sulfur. I have no idea if it is used for syntho tires.

Just curious

Brian

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The problem is that a forge doesn't burn coal to heat steel. It burns coke. The coal that's burning is just to change it to coke and is around the outside of the fire.

I don't think you can coke tire rubber and burning it will be a nasty tarry mess. You would have to figure out how to separate the burning from the metal heating. Sulfur contamination is another big issue as sulfur degrades steel.

So is it possible? You could probably figure out a way to do so with a reverbatory furnace (look it up) and it would only be many more times as expensive and as difficult that using coal or charcoal.

You know it's possible to burn diamonds as forge fuel, just not "efficient".

BTW the recycled rubber is known as "crumb rubber" according to my father who was on the board for a tire recycling business.

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Wouldn't turn into a goey nasty mess? Whenever I've burned rubber it turns into a pool of boiling toxic waste.
Just wondering....

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Hmmm. Thanks for the replies. This is a really good point. Boiling toxic waste. That is probably why it can only be introduced in small amounts like 10-15% to coal fires in calcining plants.

The references I looked at say that sulfur is present, but in lesser quantities than coal. I should have picked up a couple of briquettes of that crumb rubber to try out. It will probably not coke like coal does, but it might burn like coke or corn. Still, I was scared to try even one lump without hearing about somebody else's experiences.

The guy who showed me the pile was the local soccer coach after a game. Some of the soccer moms have already reacted negatively. "Don't burn that **** er, junk around here!"

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The fire dept. will help you put the fire out; cause it will not stop burning like coal.

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The tire recycling plant my Father was involved with caught on fire when an electrical transformer exploded; this happened *before* I moved out here. 5 years later and completely buried it's still burning under ground.

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I reckon you will get nobbled for pollution if you set fire to that rubber. You will have the local firies there in a flash with a big bill.

Cheers

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looks fairly complicated to me too.

There was a company here in Sand Springs that built a prototype tire burner.
pressurized, refractorized, and waiting EPA approval. haven't heard much on em lately.

They were shooting for a $500K units.

Several years ago the cement plant in Humboldt Ks got grant money to study burning tires as a fuel source, they quit as sooon as the grant money expired.

Lots of energy in there lots of problems...

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thinking back to when we used a few tires to help start a pit fire on a clearing jop (20 Years ago) the amount of o2 needed to get the rubber really going was amazing. So how would you force air into a pot of boiling rubber?

Edited by meinhoutexas
spelling

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It works. The firepot does not fill with boiling rubber. The crumb rubber briquettes coke just like blacksmithing coal. All the web searching and armchair thinking was no substitute for a 20 minute experiment.

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I know this is an old thread,but I worked in a rubber refinery for many years. Vulcan Corp. In Clarksville TN. Removing the stainless belting from a tire will NOT reduce zinc content in any meaningful way. The zinc isn't in the steel belting it is added to the rubber during compounding along with about silica at about a third by weight which means lots of ash. It seems to me that it would make a poor fuel and probably violate a few ordinances by being used as such. It doesn't smell very good either. If you are worried about giant piles of shredded tires they can be recompounded into New rubber easily. There's far better fuel out there that is much less detrimental to your health than burning used tires.

          Pnut (Mike) 

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