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Searles Valley Minerals, Mineral wealth

Manufacturing in Action, Source : The Manufacturer US
Published : July 2007

Searles Valley Minerals mines riches in the desert using the latest automated methods, Gary Toushek learns

The year was 1870, and the California Gold Rush was in full swing, attracting the hopeful from all over the world to the West Coast. Frustrated gold prospector John W. Searles was crossing the Mojave Desert near San Bernardino when he came upon the dried-up remnants of an ancient lake bottom. His eye caught a sun-reflective crystal formation, and he stooped to pick it up. Unfamiliar with the substance, he stuck it in his pocket, and days later he showed it to a chemist who identified it as sodium borate, or borax, a mineral salt of boric acid that has a natural cleaning ability and dissolves easily in water. Although he’d been looking for gold and found pitifully little, he’d stumbled across a mineral deposit that was almost as valuable as a gold mine.

The 42-square-mile dry lakebed eventually came to be known as Searles Lake and was found to contain some 4 billion tons of sodium and potassium minerals of the carbonate, sulfate, borate, and halide classes of mineralogy. The old prospector established the San Bernardino Borax Mining Company in 1873, and since the desert was so isolated (before the railroad was built to Mojave), the mode of transport for the borax was wagons pulled by teams of mules (hence the commercial product named 20 Mule Team Borax). First the mineral-laden, brackish brine was scooped and hauled in containers to the refinery at San Bernardino, then the refined borax was hauled 175 miles to the harbor at San Pedro, where it was loaded onto boats for delivery to various US ports.

Today more than 200 wells have been drilled to varying depths in the desert lakebed—from near-surface to over 300 feet below the salt pan—and the extracted brine travels to one of three processing plants (in the towns of Trona, Westend, and Argus) via some 900 total miles of pipeline. Once the minerals are removed, the brine is returned to the valley floor, where it is injected back through the salt layers, enabling it to recapture minerals. This “continuous renewal” method of solution mining is efficient and environmentally responsible, leaving the water table unpolluted.

The Trona facility was built in 1913–14, and a self-contained company town grew up around it, operated by the mining company to house employees, who were paid in company scrip instead of cash. The company built a library, grocery store, school, and minimal recreation facilities, and the Trona Railway was built to provide a rail connection to the Southern Pacific. During World War I, Searles Valley Minerals’ Trona plant was the only reliable American source of potash, used in the production of gunpowder. Today the soda ash processing plant has been expanded and updated with automated manufacturing equipment, also producing anhydrous borax and borax decahydrate.

Westend was also built as a company town, in 1920, and today the facility, also expanded and updated with automated equipment, produces similar boron products to the Trona plant: boric acid, anhydrous borax, pentahydrate borax, decahydrate borax, and anhydrous sodium sulfate. The Argus facility is a 117-acre power and production complex constructed in 1978 to produce dense sodium carbonate (soda ash), and it houses the industry’s most efficient co-generation systems.

The network of production wells, injection wells, and piping carries the brines to the appropriate plants, where the minerals are extracted, crystallized, screened, washed, and dried. The crystals are then baked in rotary kilns to drive off water molecules locked in the crystalline structure. This complex extraction process is generally referred to as “fractional crystallization” and includes the treatment of brines through carbonation extraction, refrigeration extraction, or solvent extraction. Salt is also harvested from the lake surface and from solar ponds with the use of heavy equipment.

Searles Valley Minerals, now encompassing a 50-square-mile area in the Mojave Desert (with corporate headquarters in Overland Park, KS), produces about 1.8 million tons of mineral products annually, which are sold to customers worldwide to make a wide variety of goods, including detergents, glass, ceramics, carbonated beverages, animal feed, and paper products. Borax is also a component of cosmetic enamel glazes and insecticide, and it is used as a buffer in biochemical fire retardant, as an anti-fungal compound for fiberglass, and as a flux in metallurgy.

The environmental aspect of its brine pipeline is just one example of the company’s efforts to be a responsible corporate citizen. Searles has recently been recognized for its considerable reduction in greenhouse gases by the California Department of Toxic Substances, says Arzell Hale, executive director of the Trona facility. Hale is in charge of environmental affairs, governmental relations, human resources, and public relations, and he says that despite California having probably the most stringent environmental regulations in the US, Searles is also working on its own projects targeting environmental health. “Not only do we do what the law requires, we go above and beyond, trying to be proactive with a lot of voluntary measures. Last year the state instituted law AB32 to reduce greenhouse gases, which requires that companies be down to their 1990 emission levels by 2020. We’re already below our 1990 levels, and we continue to reduce emissions.”

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