WYOMING DOMINATES SODA ASH MINING
Most of us don't think of soda ash (also called bicarbonate of soda or baking soda) unless we have an upset stomach or plan to bake some biscuits. However it's also used in glass manufacturing, paper, food additives, laundry products, medicine, air pollution control and animal feed. In fact, glassmaking consumes about half of soda ash output.
Until recently, soda ash was synthetically produced. Then in 1938, a sodium sesquicarbonate deposit was discovered during oil and gas exploration in Wyoming. The first mine was built in 1946 in Sweetwater, Wyoming and commercial production began in 1948. Wyoming has the world's largest deposits of sodium sesquicarbonate and is responsible for nearly 90 percent of the world's soda ash production. One reason is that sodium sesquicarbonate is a rare mineral and there are only a few locations where it is found - Africa, China, Turkey, and Mexico. But, the only site where it is commercially mined is in the Green River Basin of Wyoming.
Fifty million years ago, the Green River Basin and surrounding areas were covered by a 20,000 square mile land-locked lake. As the earth changed though the ages, the water in the lake evaporated. What was left behind was over 100 billion tons of nearly pure sodium sesquicarbonate wedged in between layers of sandstone and shale. The deposit varies in depth from 800 to 3500 feet below the surface and contains 42 layers of the mineral. Actual mining occurs at a depth of 800 to 1600 feet in beds that are 8 to 10 feet thick. A recent report by the U.S. Geological Survey estimates that the total reserve is 127 billion tons of sodium sesquicarbonate and mixed sodium sesquicarbonate/halite in beds 4 feet or more thick. This is enough soda ash to supply U.S. demand at current production rates for 6,684 years, and world demand for about 2,000 years.
Currently four companies mine sodium sesquicarbonate in Wyoming: FMC, General Chemical, OCI, and Solvay Chemical. The General Chemical mine is in Southwestern Wyoming, 40 miles west of Rock Springs and 175 miles northeast of Salt Lake City. It operates round the clock, seven days a week and its underground tunnels cover over 20 square miles. Sodium sesquicarbonate is a relatively hard mineral that once was mined with blasting. However, today, General Chemical uses more conventional methods like room and pillar mining to mine over 4 million tons of the mineral in a year.
The mine uses rotary shears and bore mining. Each rotary shear uses a single 10 foot wide drum with 90 tungsten carbide tips to rip the sodium sesquicarbonate from the ore face. The bore miner cuts a 9 foot high passage using vertical rotary arms that contain 50 tungsten carbide metal tips. The advantage of the bore miner is that it produces a finer ground ore, which makes processing easier.
After mining, the sodium sesquicarbonate goes through a series of processes that grind, heat, dissolve, filter and turn it into soda ash before shipping. The soda ash is then loaded on rail cars, where much of it is shipped to Port Authur, Texas or Portland, Oregon for export. It is Wyoming's top export and 50% of the 17 million tons produced annually are exported overseas.
Wyoming's biggest competitor in the soda ash business is China, which produces synthetic soda ash and subsidizes its export. US Senator Mike Enzi of Wyoming noted, "Hands down Wyoming's soda ash is a better product than synthetic Chinese produced soda ash. But value added taxes and rebates offered by the Chinese government discount their soda ash enough that it distorts global prices and woos buyers. We shouldn't let China leave Wyoming soda ash in the dust."
There are also environmental reasons for supporting Wyoming's soda ash industry. The synthetic process used by many other countries like China costs twice as much and generates five times the amount of waste as natural U.S. soda ash.
Soda ash is a valuable commodity inside and outside of the household. Soda ash can lower the melting point of silica sand and is used in the glassmaking process. It's also used by industries as varied as cement, waste incineration, gold and other precious metal refining, petroleum refining, pulp & paper, and electric power generation for air pollution control because it effectively removes sulfur oxides (SOx), hydrogen sulfide (H2S), hydrochloric acid (HCl), and hydrofluoric acid (HF) from flue gas emissions.