THE SEARLES VALLEY SALINE MINERAL RESOURCE
HISTORICAL CHEMICAL EXTRACTION FACILITIES
Jim Fairchild, Searles Lake Gem & Mineral Society
The John Searles Operations
The first saline mineral extracted from the Searles Valley Saline Mineral Resource was borax. From 1872 until 1897,
John W. Searles and his partners scraped naturally occurring crude borax efflorescence off the surface of the deposit.
This efflorescence was the powder that resulted from near-surface brines wicking through saline mud to the surface
and evaporating to dryness. The efflorescence was put into vats of water obtained from local mountain springs and
heated by brush-fueled fires to dissolve the borax. After allowing mud to settle from the borax-rich solution, the
solution was allowed to cool slowly to crystallize refined borax. The crystals were separated from the residual water
that contained the soluble impurities (this was discarded onto the playa surface), and the crystals were dried to
produce salable borax product.
John Searles also drilled the first wells into the saline mineral
deposit. One well, LDW1, was drilled to 300 feet
in 1888 and later deepened to 627 feet in 1896. There is no record, however, that he ever made use of the brines for
chemical extraction, or even determined the bedded structure of the mineral deposit. In 1975 well LDW1 was found to
be leaking fluid from the Upper or Lower Salt into the Mixed Layer. Because of this leakage, LDW1 was subsequently
plugged with cement.
The Trona Plant
Following the end of John Searles' operation, several other companies attempted to extract the saline minerals,
principally potash, borax and soda ash, from brines pumped from the mineral salt body (these were subsurface brines).
However, none were successful until 1915 when, during the 1st World War, the American Trona Corporation began the
first commercial production of potash outside of Germany. In doing so, they made a substantial contribution to
winning the war - potash was required to make gunpowder. The potash was produced by evaporating water from the
potash-rich brines of the Upper Salt with steam, thereby concentrating the potash enough to allow it to be
crystallized. Separation and drying finished the process. Borax was also recovered as part of this process.
In 1934, the American Potash plant (the former American Trona
plant) was doubled in capacity and extended to add soda
ash and sodium sulfate production. Boric acid, lithium carbonate, phosphoric acid and bromine production were also
added in this era. In 1948 a brine carbonation process, based on processing Lower Salt brine and mineral reserves,
was added to further increase borax and soda ash production. In 1961, the capacity for steam-evaporation was again
doubled. Then in 1962, a high tech solvent extraction process was developed and installed to triple boric acid
production. Finally, in 1964 solar ponds to seasonally concentrate the brine feeding the steam-evaporation process
began to be used. Eventually, over 1,000 acres of solar ponds were being operated, including 400 acres of ponds
where the brine was solar concentrated and then injected into the Upper Salt for recovery for plant feed the following
The Borosolvay Plant
In 1916, the Borosolvay Company joined American Trona in producing potash but was precluded from producing borax
because one owner, Pacific Coast Borax, produced borax elsewhere. This plant was shut down in 1921 after a steep
decline in the price for potash - it could not be economic without borax coproduction.
The Westend Plant
In 1927 the Westend Chemical Company began producing soda ash and borax using a brine carbonation-refrigeration
process. In 1955 the Westend Plant was expanded to add sodium sulfate production. Since Westend Chemical did not
produce potash, they based their process on the brine and mineral reserves in both the Upper and Lower Salt. Brine
was produced from these reserves using a number of wells, almost all of which were completed to allow simultaneous
brine production from both the Upper and Lower Salts. But because of this well-completion method, once these wells
were shut down, brine was free to migrate through these wells from the Upper Salt into the Lower Salt. This is the
principal method of recharge to the Lower Salt today.
Westend Chemical also drilled wells into the Mixed Layer and blended
that high-carbonate brine with the other brine
to increase soda ash production. One of these wells had a boulder-packed open hole from the Lower Salt into the
Mixed Layer. Although several attempts have been made to plug this well with cement, the presence of the boulders
made this difficult and success has not been confirmed. Another well drilled into the Mixed Layer has been lost
(no surface evidence exists), but we are quite certain that it is leaking Upper/Lower Salt brine into the Mixed Layer.
Pacific Salt and Chemical Company Operations
Pacific Salt began producing sodium chloride (common salt) from the mineral deposit in the 1940s and this operation
continues today. Their salt is largely produced seasonally by the natural flooding of the playa surface during the
winter. As the surface floods and wind and wave action move the water across the surface, the exposed salt surface
dissolves into the water to produce salt-saturated brine. Then, in the spring and summer, this salt-saturated brine
is solar evaporated to cause the dissolved salt to crystallize. This is then scraped into piles, loaded into trucks
and sold. Pacific Salt also produces some salt as a byproduct of solar brine-concentration ponds.
Occidental Chemical Corporation
From 1970 through 1972, Occidental Chemical Corporation constructed and operated large-scale solar ponds as part of
a planned new, large-scale plant. This plant was based on evaporating the brines from the Upper and Lower Salt to
near dryness, thereby precipitating the dissolved salts on the bottom of the solar ponds. The process then required
harvesting those salts, followed by physical separations (flotation and leaching) to separate these salts into salable
products. Although OCC operated up to 4,000 acres of solar ponds for two summers, they were ultimately unsuccessful
in developing a commercial business.
Argus Soda Ash Plant
In 1978 Kerr-McGee Chemical Corporation started up the Argus soda ash plant. This plant uses a brine carbonation
process to extract soda ash as the only product from the soda ash rich brines obtained from a deeper Mixed Layer
level of the mineral deposit. In 1988 the soda ash production of the Westend Plant was consolidated into the Argus
Solution Mining of the Upper and Lower Salt
Beginning with the first brine production and continuing until new reserves became unavailable, all mining and brine
production from the Upper and Lower Salt was done by simply extending well-fields into new, untapped area. Once the
reserves of high-quality brines became depleted in the late 1960's and early 1970's, solar evaporation was employed
to partially restore brine grade to initial levels. Finally, in 1995, solar evaporation was largely replaced by
controlled solution mining of the Upper Salt. This new mining method was based on selectively increasing the
concentration of borax in the brine by supplying heat to the salt body. This raises the brine temperature, and with
it, borax solubility and thus brine grade.
Recharge to the Upper and Lower Salt has always been, and continues to be, through the percolation of partially
depleted plant effluents through the surface of the Upper Salt. From the percolation area, the fluid then travels
through the salt body, equilibrating with the local minerals along it flow path to reconstitute the brine. Eventually,
it is again pumped from the salt body as feed for the chemical extraction plants, after which it again returns to the
salt body in the continuing solution mining process.
Solution Mining of the Mixed Layer
The Mixed Layer contains fifteen or more distinct mineral beds. The top nine contain mostly the mineral trona with
few other saline mineral contaminants. These trona beds are 250-325 feet below the surface where both surface and
peripheral recharge is not possible. Because of this depth, they must be recharged by the injection of effluent from
the soda ash plant. When this trona dissolves, it can yield a soda ash rich brine very suitable for soda ash production.
But to recreate brine via trona dissolution at the grade necessary for efficient soda ash production, the concentrations
of the saline mineral impurities in the injection fluid, principally sodium chloride (NaCl), must be controlled to be
less than specified targets.
Because large tonnages of trona are being dissolved, occasionally
there is subsidence around an injection well.
On occasion, this has lead to the failure of the well. When this happens, a flow path between the Lower Salt and
the Mixed Layer is occasionally opened. Because leakage of Upper or Lower Salt brine into the Mixed Layer has an
adverse effect on Mixed Layer brine grade, we always attempt to plug any leaking injection well quickly, normally
with good success.
Recent Ownership History
In December 1967, Kerr-McGee Corporation acquired all of American Potash and Chemical Corporation, including all of
the assets in Searles Valley. These included the Trona Plant and about 65% of the saline mineral reserves. In October
1974, Kerr-McGee also acquired the Searles Valley assets of Stauffer Chemical Company. These assets included the
Westend plant and about 20% of the saline mineral reserves. Then in 1990, Kerr-McGee acquired the Searles Valley
assets of Arco Chemical Company and Leslie Salt Company. These included no plants and the remaining 15% of the
saline mineral reserves.
In December of 1990, Kerr-McGee Corporation sold all of its Searles
Valley assets to D. George Harris and Associates,
and they formed North American Chemical Company from these assets. In April 1998, IMC Global Corporation acquired all
of the Searles Valley assets of D. George Harris and Associates, and renamed the operation IMC Chemicals Corporation.
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Searles Lake Gem and Mineral Society
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