Cadmium: batteries, TVs, plastics

Greenockite from Tsumeb, Namibia. 

Nobody mines cadmium. It comes from metal refineries, mostly zinc processors, where it is recovered as a trace component. It’s toxic, and not much goes a long way—only about 228 tons in the US in 2009 (down from 700 tons in 2005), with nickel-cadmium batteries (NiCd) leading the way. As lithium ion batteries, with greater energy density, take over in many small devices, NiCd batteries have declined in use, but they may return as storage batteries for on-grid solar energy systems that store electricity during the day and make it available at night.

China produces about a quarter of the world’s cadmium, and while the US is a net exporter, it ranks #9 in world cadmium production with about 4% of the total. A lot of US cadmium is exported to Asia where batteries are made.

Cadmium’s minor uses include photovoltaic devices such as photocopiers, where cadmium sulfide coats drums. Traditional uses include yellow, orange, and red pigments: yellow no-passing stripes on highways once contained cadmium. It also stabilizes plastics, makes lasers, and in phosphors gave the bluish tint to black-and-white TV sets in the 1950s. Cadmium was also once a low-melting component of solder and Wood’s metal—an alloy of bismuth, lead, tin, and cadmium sometimes used in the fusible valves found in automatic sprinkler systems. Wood’s metal melts at 158°F; when fires reach that temperature, the metal melts to open the valve, allowing water to flow.

The only noteworthy cadmium mineral is greenockite, cadmium sulfide, which forms pretty honey-colored crystals shaped like hexagonal barrels.

Photo by Christian Rewitzer, via Wikipedia under creative commons license.

Barite helps find oil

Barite roses from Kansas. R.I. Gibson photo.

Barite is a fairly common mineral, barium sulfate, frequently represented in collections. Its noticeably high specific gravity, 4.5, together with interesting crystals and occasional fluorescence make it popular with mineral collectors. Iron-bearing red sand incorporated into its crystalline aggregates makes barite roses, the state rock of Oklahoma. Gypsum crystals with sand in their matrix make similar “desert roses.”

From 2005 through 2008, the US consumed more than three million tons of barite each year. This volume fell to under two million in 2009 thanks to the recession and its impact on oil and gas consumption because 95% of all the barite used goes into drilling fluids for oil and gas wells. Barite’s density helps control high subsurface pressures.

Barite finds its way into many other uses, volumetrically smaller than oil and gas drilling but more directly pertinent to consumers. It helps protect metal in brake linings and adds gloss to automobile paint. Truck mud flaps, auto tires, home carpet backings, and playing cards include barite for weight, strength, and stiffness.

As a radiation blocker, barite shields x-ray machines and nuclear reactors, and creates the x-ray-opaque contrast medium for intestinal soft-tissue scans. A use that is declining as flat-panel technology expands is in the glass of cathode-ray tubes, where barium carbonate reduces radiation from old-style televisions and computer monitors.

About 80% of US barite is imported, virtually all of it (93%) from China, world leader with more than half the production (India is #2 with about 15%). The 20% of US consumption mined domestically is mostly from Nevada; the US industry employs about 330 workers in a $20 million business, representing about 7% of the world’s barite.

Photo: Barite roses from Kansas. Photo by Richard Gibson. 

Arsenic

Orpiment (arsenic sulfide)

Arsenic is Bad Stuff. It may have contributed to Napoleon’s death (accidentally or otherwise) and its presence in water supplies is an ongoing concern. For many years the wood treatment industry in the US consumed most of the arsenic used here, because it is an excellent preservative and insecticide. But toxicity issues led the industry to voluntarily cease using chromated copper arsenate for human-contact lumber like decks and picnic tables in 2003. Total US arsenic consumption has fallen from more than 30,000 metric tons in 1998 to 3,600 tons in 2009.

But arsenic finds its way into a lot of other critical but low-volume uses. It strengthens grids in lead-acid batteries, combines with other metals in some ammunition, and is a vital component of semiconductors in solar cells, circuit boards, and telecommunication electronics. Light-emitting diodes (LEDs) in computers, CD players, and numerous other household electronic devices contain gallium arsenide phosphide in tiny amounts. Two pounds of gallium arsenide can make 500,000 LEDs.

There are some arsenic ore minerals, mostly arsenic sulfides like lemon-yellow orpiment and red-orange realgar, but the primary ore is arsenopyrite, iron arsenic sulfide. It is also common in other minerals mined for elements like copper, and arsenic contributes significantly to environmental problems in copper-mining regions.

All US arsenic is imported. 86% of arsenic metal comes to the United States from China, which produces about half the world’s arsenic.

Orpiment photo from USGS via Wikipedia (public domain).

Sapphires

I recently completed an article on Montana sapphires for Distinctly Montana Magazine, focused on beautiful gems from Yogo Gulch. But sapphires have practical uses too.

Because rubies (red) and sapphires (famously blue, but also pink, yellow, green, purple, and even colorless) are nothing more than corundum, aluminum oxide, with some interesting trace elements (mostly titanium and iron), they are very hard—number nine on the Mohs Hardness Scale, second only to diamond. Consequently they find their way into watch and clock bearings, and those that don’t make the cut as gems are sometimes used as high-quality abrasives.

The first lasers, in 1960, used synthetic rubies to focus light into a coherent beam. Solid-state integrated circuits sometimes use sapphires formed into small thin wafers as their insulating substrate. Larger sheets built from synthetic sapphire sometimes make tough windows in armored vehicles, as well as mundane surfaces such as grocery-store barcode scanners where scratch resistance is valued. High quality watches may have sapphire crystal faces in addition to gem-like bearings inside.

Even though Auguste Verneuil invented a process for making synthetic sapphires in 1902, natural sapphires were used for non-jewel applications for decades after that. Today about 250 tons of synthetic sapphires supply the world annually with watch bearings, abrasives, and specialty uses. The US and Russia manufacture most synthetic stones, while Madagascar is the leading gem sapphire producer.

Watch for the article on Montana’s Yogo sapphires in the Summer issue of Distinctly Montana.

Image: The 182-carat Star of Bombay star sapphire, via Wikipedia.

Sandstone facades

Buildings are built of many things. What Things Are Made Of has one chapter about simple home construction and another including monuments and office buildings. I’m involved in planning for the Butte-Silver Bow Courthouse Centennial, coming up in 2012. It’s a huge Beaux-Arts creation whose cost was comparable to that of the Montana State Capitol in Helena.

The first floor façade’s rectangular panels boast uniform, fine-grained gray sandstone. A close look (or better, a careful look from a certain distance) reveals the sandstone’s beds to be angular, curved—not the expected planar laminations. The arrangement is called cross-bedding, crosscutting layering that means the sand was deposited in active rivers. The beds are essentially little sand dunes, channels, and other river-bed forms carved by flowing water.

The sand solidified into sandstone about 78 million years ago near what is now Columbus, Montana. Quarrying there began about 1890. Under the leadership of stonemason Michael Jacobs, born Jacobucci in Italy, the Montana Sandstone Company provided facing stone to numerous buildings in Butte, but it was the contract for the Montana State Capitol that put the company on the map and established Jacobs’ fame and fortune.

Today, stone decorating buildings is called dimension stone, and 78% of that used in U.S. construction is imported, with Brazil, Italy, China, and Turkey supplying nearly equal amounts. Brazil, China, and Italy provide mostly granite and Italy is also a major source of marble. Imported stone was worth $1.5 billion in 2009, compared to $377 million for domestic products. The U.S. is the largest consumer of these materials in the world.

What Things book: Update

For the three or four of you who are chomping at the bit for What Things Are Made Of to come out, here’s a quick update. It’s almost done. 92,000 words, about 320 pages laid out as a 6x9 paperback. I still have to complete the references, index, and one annoying section in Chapter 7. Then I have to evaluate print-on-demand shops and figure out e-pub formats and make some decisions. I’m anticipating January or February 2011 for an availability date.

Thanks for the interest and support!

Manganese from Gabon

And we’re back… it was a busy and complicated summer and I’ve spent a LOT of time actually working on and thinking about What Things Are Made Of. The book is now at just over 80,000 words, with 8 chapters finished (two need some expansion and tweaking, and a summary chapter yet to complete). I'm looking at print-on-demand and E-book for actual publication.

I learned an interesting tidbit about manganese, a metal the U.S. uses mostly in steel alloys and imports at a rate of 100%. Our primary supplier is little Gabon, with 57% of our manganese ore imports. Gabon’s manganese is associated with a pretty cool location – the only natural nuclear reactor known on earth.

A little over two billion years ago fissionable uranium isotope U235 was more abundant in uranium deposits, at nearly three percent, than it can be today simply because over those two billion years most of it has decayed to lead. Evidently critical mass was reached in a uranium deposit back then, and nuclear reactions happened. It’s not perfectly clear why the manganese is associated, but it’s enough to make manganese Gabon’s second most valuable export. $100,000,000 worth came to the US in 2009 – but that pales in comparison to Gabon’s oil exports to the US, valued at $2,200,000,000, twenty-two times the manganese value.

Manganese steel is critical in construction, so the late 2000s recession has taken a toll. US manganese consumption in 2009 was a third of its use in 2006, but it is still a half-billion-dollar business in the United States.

A brief introduction to fireworks

Like gunpowder, fireworks are mostly sulfur, saltpeter and carbon but with diverse agents added for color. They originated in China about 1000 years ago as a variation on black powder. April 18 commemorates the invention of firecrackers by Li Tian, a Chinese monk who lived near Liu Yang in Hunan Province, the region that supplies most of the world’s fireworks to this day.

Strontium carbonate (red) and barium chloride (green) tint modern skyrockets and other fireworks. Lighter red may come from lithium carbonate with orange provided by calcium chloride. Blues usually indicate the presence of copper compounds, which also produce purple when mixed with strontium. Rarely, rubidium generates purple. Sodium makes yellow, iron makes gold. Burning titanium, aluminum, or magnesium metal powder is the basis for intense white or silver stars. Strontium also makes red color in highway flares.

More information here.

Photo in public domain, via Wikipedia

Earthenware or stoneware?

My apologies for no posts. I’ve been busy doing walking tours, driving the Butte Chamber trolley, and working on a booklet and exhibit for artifacts from the 2007 Butte Chinatown archaeological dig. The dig unearthed pieces of opium pipes, some of which are earthenware and some are stoneware. Today’s post focuses on differences in those two types of ceramic.

Both earthenware and stoneware are essentially fired clay, though proportions of components vary widely. Stoneware is usually fired at higher temperatures (up to 1300º C vs. temperatures more in the range of 1000º C for earthenware), which gives it a denser, more vitreous texture.

At the heart of such ceramics are clays—fine-grained sheet silicates similar to mica. Their structures can incorporate water, and when fired, such clays effectively collapse into denser structures, or even metamorphose (change form) into other, denser minerals. Ball clay, so named because historically 35-pound cubes of clay became rounded during shipping, is a common constituent. It is usually mixed with varying amounts of kaolin (another clay mineral), quartz, and feldspar to make ceramics.

In the United States, Pennsylvania was a historical major producer of ball clays. In Europe, Devonshire, England was an important source. Today, 63% of U.S. ball clay production comes from Tennessee.

Ceramic earthenware and stoneware such as dishes and bowls is a tiny volume of all clay consumed. Most ball clay in the U.S. serves as fillers and plasticizers in floor and wall tiles, and in the ceramics that become toilets and sinks.

The clay industry in the United States is a $1.4-billion business employing about 5400 workers in 41 states.

Photo of opium pipe from Butte Chinatown archaeological dig courtesy of Mitzi Rossillon.

The oil leak

Current (late May 2010) estimates of the rate of leakage in the Gulf of Mexico well are 12,000 to 19,000 barrels a day. Pretty bad, and significantly worse than early estimates.

With total U.S. oil consumption at 19,714,000 barrels a day (May 21, 2010), the leak at 15,000 barrels per day would take 1,314 days (more than 3½ years) to equal one single day of U.S. oil consumption.

The point is not to belittle the disaster—it's an awful thing—but rather to point out the gargantuan scale of U.S. oil consumption.

Offshore oil

In the wake of the disastrous oil leak in the Gulf of Mexico, visitation to my website’s oil pages has spiked to over 1000 unique visitors a day, as it does when the price goes up or hurricanes or wars interrupt our guzzling. There is plenty of information out there, so I see no need for me to expound on much about the problem. But I need to address one issue, the demand from some that we put an end to offshore drilling and production because it is so dangerous.

I’m as much or more of an “environmentalist” as many are. Most geologists are, because they love the earth. That does not mean we reject the value of earth products, whether oil or copper or neodymium. But those who would eliminate offshore oil exploration and production need to realize one thing.

More than a third (37% in December 2009) of U.S. domestic oil production comes from offshore wells.

Federal offshore areas (mostly in the Gulf of Mexico) produce more oil than any state. More than Texas, more than Louisiana, more than Alaska. More than 2,000,000 barrels a day in December 2009. Shut it off – and replace it how? There is no replacement source that can be tapped economically, if at all. By the time any new discoveries come onstream, in seven to 15 years from now, existing production will have declined by that much or more: we will only maintain the status quo if (IF) we discover and develop that much production. The only significant possible locations for those high-volume discoveries are offshore, and there is no guarantee that it exists at all.

To quote a fine summary (available here), “America simply doesn’t get it.”


Public domain image of offshore platform. Credit: NASA.

The kitchen floor

Last night I went to a Butte history talk focusing on home furnishings about 1910. Among the multitude of state-of-the-art items anyone could buy at Butte’s Hennessey’s store using the newly invented time payment plan (a.k.a. credit) was linoleum flooring.

Invented in England in the late 1850s, linoleum's basis was solidified linseed oil derived from flax plants. It gave a tough but flexible material. Minerals extend and improve the properties: finely ground limestone or whiting may comprise a third of linoleum’s volume while clays add flexibility and also serve as extenders or fillers.  Various other additives—sawdust, gum, pine rosin—also help give linoleum its desirable properties.

An unusual mineral, wollastonite, calcium silicate, crystallizes as tiny elongate needles or blades. This geometry helps bind other materials together, and as tough little bars, wollastonite makes linoleum stronger while maintaining its flexibility. It’s a chemically stable mineral that helps linoleum resist chemical attack and cracking over a wider temperature range than wollastonite-free material.

Although wollastonite deposits were exploited in Inyo, Kern, and Riverside Counties, California, from 1930 to 1970, the largest wollastonite mines in the U.S. are in Essex County, New York, in billion-year-old rocks of the Adirondack Mountains. The ore is processed at Willsboro, and together with another mine in Lewis County makes wollastonite New York’s fifth most valuable non-fuel mineral product. Almost all U.S. wollastonite production today comes from New York, adding up to about a quarter of all produced in the world. That ranks the U.S. at #3 for wollastonite, following China and India which together account for about 70% of world production.

Thanks to the New York mines, the U.S. is largely self-sufficient in wollastonite production, with something like 5% of consumption imported. India is the leading source of those imports, but China, Canada, Germany, Finland, Japan, and France also ship small volumes to the U.S.

Wollastonite finds its way into ceramics, metallurgy, paint, plastics, caulking compounds, friction products such as auto clutches and brakes, and synthetic rubber including auto tires.

Much “linoleum” today is really polyvinyl chloride, made from natural gas and salt. Although Frederick Walton patented his linoleum-making process in 1860, he failed to trademark the name and lost lawsuits alleging others who used the word infringed on his trademark. Consequently, “linoleum” is considered the first product name to evolve into a generic term—and it happened just 14 years after its introduction.

Wollastonite specimen image from U.S. Geological Survey via Wikipedia.