(GP/GT) for Additional Water Supply in the Lower Rio Grande

1II-28
1lI.B-S&6
BYPRODUCT SALTS RECOVERY, WITII OR WITIIOUT EVAPORATION PONDS
The most obvious example of economic recovery of various inorganic salts from brines is at the Great
Salt Lake in Utah. There, the Great Salt Lake Chemicals Company has been extracting various salts for
the last six decades and treating them to produce purified versions of useful industrial chemicals such as
the Chlorides of Sodium and Magnesium, the Carbonates of Potassium and Calcium, etc.
Near the Searles Lake area of California, a similar operation is recovering chemical values from mixed
salts pumped out of these deep brines and commercializing many compounds, in addition to the chemical
elements Bromine and Iodine. Midland, Michigan, and Owens Lake brines are yet two more examples
of this kind of byproduct recovery.
All of the above utilize large-scale settling and evaporation ponds (most of them man-made except, of
course, for the Great Salt Lake itselt), to permit the sun's power to drive off all or most of the water,
depositing a dense layer of solid, mixed, inorganic salts on the "hardpan" or lake or pond bottom. After
several years of this type of settling and compaction, the salt beds are strong enough to sustain the weight
of harvesting machinery, which gathers these salts and conveys them to a beneficiation plant for further
separation and purification prior to sale.
If the LRGV-region brines from GP/GT sources possess salt compositions somewhat similar to those
found from the Pleasant Bayou Brines (from the USDOE Test Well), then one would expect to find
significant concentrations of the Chlorides and Carbonates of Sodium, Potassium, Calcium, Magnesium
and Strontium, with much smaller quantities of Lithium, Manganese and Barium and recoverable
quantities of Bromine. Obviously, until the analyses of these LRGV brines become defmitely established,
one cannot attempt any meaningful development of recoveries and subsequent commercial values.
The question of whether to recover these salts after a period of natural evaporation by sunlight - which
would require extensive acreage to be set aside for long periods of time - or by passage through an
inorganic salt recovery plant is again one of economics, determinable only after some good and reliable
analyses are at hand for the basic mixed-salt composition. On the one hand, it can be said that use of
settling and evaporation ponds constitutes the least expensive initial investment, but a sizeable cost pattern
for harvesting and beneficiation, whereas the Chemical-plant route bespeaks a high initial capital
investment and a moderate to high cost of beneficiation, if the relevant concentrations are high enough
to be economically recoverable.
One interesting alternative that has been advanced, emanating from modern Israeli practice, is to create
adequately sized evaporation ponds that can also accommodate binary-power generators, so that the costs
of electricity to run the plant are importantly defrayed, at least in part.
Another economically viable alternative is to harvest the entire salt mixture, dry it adequately and sell
the mixture as such to a chemical company that needs an assured source of this type of raw material for
further processing. As it stands, all such chemical companies are forced to locate near their sources of
raw materials and this would be an attractive way in which to induce the location of one or more such
chemical companies to the LRGV region, for the start of a new industry, reasonably balanced between
capital intensity and labor intensity.