March 1, 2013
What in the world is he talkin’ about?
By Bill Langer
The scene: Our home in Anthem, Ariz., a suburb of Phoenix, located in the Sonoran Desert.
It was 8:30 p.m. My wife, Pam, turned on the light in the bedroom and sent a surprised scorpion scurrying across the hardwood floor. Pam let out a scream, and our dog, Rosie, rushed in to investigate. By the time I arrived, Rosie and the scorpion were in a faceoff; the scorpion waving its nasty claws and displaying its curved tail, ready to sting anything that got within reach. Pam was trying to get Rosie away from her foe. I stomped the intruder.
Pam and I decided that we would rather not repeat the incident, so the next day I spread a white powdery substance along the foundation of our house. I am not going to tell you what the stuff was right now. However, if you do not already know what in the world I am talkin’ about, you will by the end of the article.
During 535 A.D., this material was used in lightweight bricks for the construction of a 100-foot diameter dome for the Church of St. Sofia in Constantinople. Even earlier, the Greeks and Romans describe “floating bricks” that probably were made from this same stuff.
The first significant industry utilizing this material started off with a bang — literally. Circa the 1860s, Swedish industrialist and engineer Alfred Nobel constructed bridges and buildings in Stockholm. He used various methods to blast rock, including nitroglycerine. Unfortunately, Nobel’s nitroglycerin factory blew up, killing his younger brother and several other people. In 1867, motivated to find methods to lessen the dangers of handling nitroglycerine, Nobel discovered that mixing nitroglycerine with kieselguhr (the German name for subject material) would turn the nitroglycerine into a malleable paste that was reasonably safe to handle. Nobel named his invention dynamite.
In 1900, U.S. kieselguhr production was reported to be about 3,300 tons. Uses included beer filtration (still one of its primary modern applications) and other fluids, building materials, polishing compounds, and as filler in rubber, paint, roofing, and paper. During the 1920s, the development of processing techniques including calcination, grading, and sizing, opened up a whole new suite of market applications.
Today, production of kieselguhr has reached more than 880,000 tons per year. The most important use today still is as a filtration medium for beverages, including beer (more than 100 years of filtering the brew), wine, sugar, food oils, petroleum, and water. It has specialized pharmaceutical and biomedical uses, including filtering of life-saving drugs like tetracycline and insulin. Kieselguhr is used in oilfields as a coagulant for water that is co-produced with oil. Aggregate producers may use it as an absorbent for oil spills. Ready-mix operators may use it to strengthen portland cement. The list goes on and on.
Kieselguhr consists of the hard silica shells of microscopic algae called diatoms; hence its modern name of diatomite or diatomaceous earth (DE). Billions and billions of these long-dead, microscopic water creatures collect in sedimentary deposits that can be mined to exact revenge on any scorpion who dares to penetrate the perimeter of our home. We used food-grade DE because we have grandkids and a pet. Apparently, the diatomite adheres to the waxy exoskeletons of insects, cuts into the insect’s joints, and body fluids escape causing death by dehydration.
No scorpion has been inside our house since that infamous night…at least not one we have seen.
Now that’s what I’m talkin’ about.
Bill Langer is a research geologist who spent 41 years with the U.S. Geological Survey.
He can be reached at Bill-Langer@researchgeologist.com