Prospecting the Vulcan Hills for Treasure

NewScientist
Until relatively recently, most used rubber vehicular tyres were buried in landfills and left to slowly rot. But now there are dozens of productive uses to which these rings of vulcanised rubber can be put. A better way of making steel is only one of them:

To conventionally make steel, coke, which is charcoal from coal, and limestone are shoved into a furnace heated to more than 1500º Celsius. The calcium in the limestone scavenges impure elements in the coke, such as silicon and aluminium, creating foamy slag and the product we're after - liquid iron. Just like cappuccino foam, the slag sits atop the liquid iron and insulates it, speeding up the processes of converting coke to iron.

Sahajwalla found that replacing some of the coke with recycled rubber created a more effective slag blanket. The extra heat produced from it reduced energy consumption, and produced more steel. It was the ultimate win-win. Following successful commercial trials in 2007, the technology is now being used in steel mills across Australia and has diverted well over 70,000 tyres from landfill. "It's so satisfying and so exciting," she said. _NS

Another intriguing use for old rubber tyres is to produce carborundum -- silicon carbide -- for tough bits, blades, and tools.

Silicon carbide, known commercially as carborundum, is formed of carbon and silicon atoms arranged in a diamond-like pattern, which results in diamond-like properties. On the Mohs scale of mineral hardness, which has diamond as ten, carborundum scores nine or better. It thus has a wide range of uses, from abrasives and cutting tools to bullet-proof vests and ceramic brakes in sports cars. It is also used as a semiconductor in high-voltage applications.

Normally, silicon carbide is produced by heating sand (which is made of quartz, or silicon dioxide) in an electric furnace with carbon made from oil or coal. The trick used at Tubitak is to get both the carbon and the energy from tyres.

First, the tyres are gasified, a process which is similar to burning but involves less oxygen. This releases a mixture of hydrogen and carbon monoxide, known as syngas, and leaves a residue of amorphous elemental carbon called carbon black. Tyres also contain sulphur, which is added as part of the process of vulcanisation that makes rubber into a suitably resilient material. Gasification liberates this in its elemental form, making it easy to recover. Burning a tyre, by contrast, produces sulphur dioxide, a noxious pollutant.

The carbon black is then mixed with sand and the mixture is heated to between 1,400ºC and 2,100ºC in a syngas-fired oven. The result is high-grade silicon carbide. _Economist

Tyres can also be used to produce valuable oils, carbon black for making more tyres (as reinforcement), and to generate electricity, via pyrolysis.

[Besides re-treading,] Other common uses for scrap tyres include sports and recreational surfaces, landfill engineering, carpet underlay/floor coverings, and road building. Roads manufactured using crumb rubber last longer, have better traction and reduce noise. _Source

Tyres can also be used as structural members when baled, or formed into special block structures.

One can build entire houses and other structures out of used tyres, using the "Earthship" method, the tire bale method, or other creative methods of recycling.

And of course there are always the tyre swing, tyre planters, concrete-filled tyres used as bases for upright poles, rubber sandals made from tyres, and many other commonplace home and hobby uses for worn-out tyres.

The basic point being made is that new and important uses are being found for what was once viewed as trash and environmental hazards. That is where the attention of environmentalists, Greens, activists, and concerned citizens should be focused. Toward innovations which turn the trash into treasure.

Resource Scarcity vs. Human Ingenuity

Humans have been quite adept at finding solutions to the problem of scarce natural resources: finding more abundant substitutes for various natural resources, exploration for and discovery of new reserves, recovery and recycling of materials, and, perhaps most importantly, the development of new technologies that economize on scarce natural resources or that allow the use of resources that were previously uneconomical. _Krautkraemer2005PDF

Predictions of resource scarcity and accompanying doom have become common among late 20th and early 21st century pseudo-intelligentsia. And yet predictions of doom with fixed due dates invariably fail.

In 1980, Julian Simon, the recently deceased economist and author of The Ultimate Resource, offered to environmentalists a wager based on his assertion that the price of any raw material would indefinitely decline on a future date. The wager was taken up by Paul Ehrlich, author of the best- selling 1968 book, "The Population Bomb," which predicted that during the 1970s "the world will undergo famines -- hundreds of millions of people are going to starve to death...

"In October 1980, Ehrilch and Simon drew up a futures contract obligating Simon to sell Ehrlich the same quantities which could be purchased for $1,000 of five metals (copper, chrome, nickel, tin, and tungsten) ten years later as 1980 prices," writes Ronald Bailey in his book EcoScam. "If the combined prices rose above $1,000, Simon would pay the difference. If they fell below $1,000, Ehrlich would pay Simon. Ehrlich mailed Simon a check for $576.07 in October 1990." During the 1980s the combined prices of the metals selected by Ehrlich declined by over 50 percent. Simon easily won because he knew that the supply for resources was not becoming more scarce but more abundant, since the economic history of predominantly free capitalist nations had demonstrated how the prices of most major commodities have declined over time.

While Simon was proven correct, Ehrlich went on to win a MacArthur Foundation "genius" grant -- based on his career of fantastic apocalyptic predictions that never came true. _Capmag

Human ingenuity in the face of resource scarcity is an old story, dating back many tens of thousands of years, at least. A fascinating ongoing chapter in this story involves a fantastic new field of chemistry that is enticingly close to "alchemy":

According to the authors of the paper, it is possible to mimic certain properties of precious metals as platinum and palladium using combinations of far more mundane materials. And that opens up the prospect of replacing expensive strategic metals in many industrial applications by much cheaper alternatives.


...Now the team is working its way across the big central block of the Periodic Table, consisting of so-called transition metals from scandium – used in aerospace alloys – to gold. Their aim is to discover other superatoms, and to gauge the extent of their similarities to standard atoms.


Not surprisingly in view of the commercial implications of success, the Penn State team is not alone in its quest. Researchers at Virginia Commonwealth University recently announced that a cluster of eight caesium atoms plus a vanadium atom mimic the magnetic strength of manganese. The research team has also predicted that superatoms of gold and manganese will be magnetic while not conducting electricity – a combination making them useful in some biomedical applications.


Such discoveries suggest we are witnessing the birth of a whole new branch of chemistry, and one that could not have arrived at a better time – for many critical technologies are crying out for a breakthrough in material science. _TheNational

Julian Simon's book, "The Ultimate Resource 2:People, Materials, and Environment" is free online and worth a look.

A look at "The Ingenuity Gap"

Improving on Garbology in an Idiocracy

Remember the "Great Garbage Avalanche of 2505?" If modern garbology tycoon David Stoller has his way, there will never be a great garbage avalanche. Stoller aims to shrink-wrap garbage in a clean and efficient manner, so that the garbage can later be used to generate energy through plasmas or fuel cells.

TransLoad's equipment compresses tons of garbage into dense cylindrical bales and seals them hermetically in several layers of plastic film. The company intends to load those bales into boxcars, and ship them to its landfills.

TransLoad claims that the combination of compaction, shrink-wrapping and rail-based shipping makes the system cost-effective and eco-friendly.

....Compressing the garbage at a rate of 1,400 to 1,600 pounds per cubic yard prevents liquid from pooling in the bales, which in turn prevents putrefaction and foul odors.

Sealing the waste in impermeable plastic prevents the escape of groundwater-polluting leachate associated with standard landfill storage.

And shipping by rail eliminates the need for greenhouse gas-emitting trucks, a point the company's PR firm is quick to emphasize in the wake of Al Gore's Oscar win for An Inconvenient Truth.

....A variety of conversion technologies, including ones that use landfill gas to generate electricity, are being explored by garbologists in Europe and the United States.

Thompson notes that several bioreactors are already in operation across the country. And a company called Geoplasma plans to build a facility in St. Lucie County, Florida, that will use plasma arc technology to convert waste into gas that can be used to generate electricity.

Stoller looks forward to the day when TransLoad's bale-stuffed landfills will function as enormous trash-powered fuel cells.

Source

Rather than a health hazard, garbage may come to represent a rich new source of "renewable" energy. One small step toward sustainability, when combined with optimal recycling technologies.