The U.S. is the
undisputed king of soda ash deposits. Soda ash is sodium carbonate, (NA2CO3), (as
distinguished from sodium bicarbonate, or baking soda). The Green River area of
Wyoming hosts the largest soda ash deposits in the world and the U.S. is estimated
to have 92% of global soda ash reserves. By some accounts, this deposit adds up
to 2000 years of supply. Soda ash can also be manufactured with limestone and
salt (NaCl) which are abundant, but the process is more costly and environmentally
destructive than mining. China is the largest manufacturer. New mines are being
developed in the Green River area. The mineral ore from which soda ash is
derived is known as trona. Trona ore is filtered, concentrated, crystallized, and dried into soda ash, a white powder. The Wyoming deposit is in Sweetwater
County. This deposit supplies 90% of the soda ash used in the U.S. The vast
underground mines are 1600 ft below the surface and equipped with all amenities for
the workers. According to the Wyoming Mining Association:
“This mineral is Wyoming’s top export and is shipped to
markets around the globe. Wyoming mines
produced over 17.4 million tons of trona and employed 2,225 people in 2018.”
There are some
trona mines in California as well. Soda ash can also be extracted from sodium-rich
brines, typically in solution-mining operations where mines are flooded. Some information,
data, statistics, and mining depictions are shown below.
Soda ash is used
in the manufacture of baking soda (sodium bicarbonate, although it is also
mined from nahcolite ore) glass, soaps and detergents, water purifiers,
insulation, flue gas desulfurization equipment, paper and more. Soda ash is desirable
as a source of alkalinity has a pH of 11.6. It is considered to be a weak base
that separates in solution into sodium and carbonate ions. It is used to raise
pH in swimming pools. The Wyoming Mining Association notes:
“Glass making consumes about half of the soda ash,
followed by the chemical industry, which uses about a quarter of the output.
Other uses include soap, paper manufacturing, and water treatment, and all
baking soda comes from soda ash, which means you probably have a box of Wyoming
trona product in your kitchen.”
They also note
that we eat this Wyoming rock quite often since it is used to make both baking
soda and baking powder:
“Baking soda and baking powder both come from soda ash,
so most Americans have a product of Wyoming trona right in their own kitchens.
These two common household substances are important ingredients for making
bread, cookies, cakes, and other baked foods. You eat this Wyoming rock every
time you bite into a sandwich, peanut butter cookie, or chocolate cake.”
New mines are in
progress for the Wyoming deposit. Due to NEPA requirements for environmental
impact statements, which take 4 years or more on average, 8 years is a common
timeframe between planning and realization. WE Soda Ltd., a subsidiary of
British-based Ciner Resources company announced plans in 2022 for their Project
West mine, hoping to be in production in 2030. Project West is expected to cost
$2.6 billion. They plan to power a portion of the mine with renewable energy
and recycle a portion of the water used in processes. One problem for the
company is the lack of workers' housing in the region.
The Green River
Basin is a lacustrine basin, or a large inland lake that eventually dried up
and was filled with sediment. The Wyoming Mining Association describes the geology
and origin of the trona deposits:
“The deposition of trona in Wyoming started about 50-60
million years ago during the Eocene Age in the Wilkins Peak Member of the Green
River Formation. A large freshwater lake, Lake Gosiute, covered an estimated
15,000 square miles in a basin in southwestern Wyoming. The lake was fairly
shallow and evaporated rapidly and repeatedly creating a climate that changed
back and forth between humid and arid, trapping the once abundant life.”
“All the minerals and mud settled in the bottom of the
lake and sodium, alkaline and bicarbonate, were transported to the lake by
runoff water. The mixture of all these elements formed the trona deposits we
mine today.”
Room-and-pillar
mining is the most common trona mining method. USGS describes the process as
follows:
“…carving a series of rooms 20- to 30-feet wide while
leaving pillars of ore 20- to 90- feet wide and as high as the ore bed to
support the mine roof. When mining reaches the end of a section of ore, called
a panel, the direction of mining is generally reversed (called the “retreat”)
in an attempt to recover as much of the ore from the pillars as possible.
Pillars are mined until the roof caves; that section of the mine is then
abandoned. Generally, 50 to 60 percent of the minable ore is recovered using
this system, although higher amounts are possible.”
Trona ore
processing involves crushing it, heating it to drive off gases, adding water,
filtration, and evaporation. The resulting slurry is then centrifuged to
separate the remaining water and soda ash crystals. The crystals are then
dried, screened, and stored for transport.
Tata Chemicals’ Plans to Power Trona Mining Operations
with Nuclear Micro-Reactors
Another Green
River soda ash mining player, Tata Chemicals Soda Ash Partners, is exploring the use of nuclear reactors to power mining operations. The plan under review is to
use eight 50MW microreactors to provide up to 400MW of power. They recently
signed an agreement with BWXT Advanced Technologies to install the reactors by
the early 2030s. BWXT’s Advanced Nuclear Reactor (BANR) is a transportable,
high-temperature gas-cooled microreactor.
“Once deployed, BANR microreactors would deliver
on-demand electricity and process heat that is both carbon-free and resilient
from external disruptions for one of the world’s leading producers of
high-quality soda ash,” said Tata Chemicals in a press release.
Energy demands are high in trona mining, especially for the
heat step in processing.
“The BANRs utilize Triso fuel, an innovative technology
known for its enhanced safety and efficiency. This fuel type consists of
uranium kernels coated with multiple layers of carbon and ceramic materials.”
The BWXT
microreactor design was aided by the US government’s Advanced Reactor
Demonstration Programme. The mining facility has been in operation since 1968 and
is in daily operation. These kinds of ‘transportable’ and small-scale nuclear
reactors may offer a boon to decarbonizing energy-intensive mining and
processing operations. Other energy-intensive industries, such as data centers
are also exploring small-scale nuclear power as a low-carbon energy supply.
References:
US to
mint nuclear power from soda mine with eight 50 MWt microreactors. Aman
Tripathi. Interesting Engineering. December 20, 2024. US
to mint nuclear power from soda mine with eight 50 MWt microreactors
Sodium
carbonate. Wikipedia. Sodium
carbonate - Wikipedia
Trona.
Wikipedia. Trona - Wikipedia
New
Wyoming Soda Ash Mine Expected To Create Over 2,000 Jobs in Sweetwater County. Cowboy
State Daily. October 12, 2022. New
Wyoming Soda Ash Mine Expected To Create Over 2,000 Jobs in Sweetwater County |
Cowboy State Daily
Project
West Puts $2.6 Billion Cost On Massive Wyoming Trona Plant. Pat Maio. Cowboy
State Daily. February 27, 2024. Project
West Puts $2.6 Billion Cost On Massive Wyoming Trona Plant | Cowboy State Daily
Going
Underground In One Of Wyoming's Trona Mines. Renee Jean, Cowboy State Daily.
November 23. 2023. Going
Underground In One Of Wyoming's Trona Mines | Cowboy State Daily
What
is soda ash and what is it used for? Alexander Johnson. Science Oxygen. September
3, 2022. What
is soda ash and what is it used for?
Trona.
Wyoming Mining Association. Wyoming Mining
Association: Trona Mining
Potash,
Soda Ash, and Borates. Energy and Environmental Profile of the U.S. Mining
Industry. November 2013. ITP
Mining: Energy and Environmental Profile of the U.S. Mining Industry: Chapter
3: Potash, Soda Ash, and Borates
Soda Ash.
U.S. Geological Survey. 2024. Mineral
Commodity Summaries 2024
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