Brine ponds are water impoundments that can contain a relatively heavy concentration of
dissolved salts and other minerals. These ponds are frequently used to extract valuable minerals such as lithium, sodium, iodine, magnesium and more. Exposed to solar radiation, water from shallow ponds evaporates and concentrates the remaining mineral-rich liquid. As the concentration increases, the minerals are triggered to precipitate and form crystals on the bottom and sides of the pond, which are ideal for harvesting.
Evaporation is the oldest form of salt harvesting and is still widely used today. Traditionally, brine ponds are simply shallow, lined basins and even today, the model has changed very little. This gives brine pond mining significant cost advantages over other methods of extracting salt or minerals.
How Does Brine Get Produced?
Brine is created from a surprising range of sources. Some of the most common are:
●Desalination Plants
These plants are employed to produce fresh water from seawater, but as the mineral concentration increases, there’s a point where no more usable fresh water can be extracted. The resulting 30 to 50 percent volume of liquid is so highly concentrated that ocean release is harmful to the environment. At this point, solar evaporation is the only disposal option.
●Food manufacturers
Food manufacturers use brine to make pickles, olives, and to treat several kinds of meat to improve flavor and texture. Highly acidic vinegar brines are used to pickle just about anything on the planet and is used in canning and preserving.
●Oil and Mining
Both mining and oil industries rely on salty and caustic liquids to separate valuable product from the matrix or other crude elements during refining.
●Paper and Pulp
Paper and wood pulp industries use salt rather than chlorine to bleach raw materials, which is undoubtedly an improvement from an environmental standpoint, but the resulting salty-laden wastewater also requires special handling.
●Textile and Tanning
Many types of manufacturing processes, particularly in textile and leather tanning industries, produce large amounts of highly concentrated brine. Brines from leather processing often contain additional corrosive and reactive ingredients like chromium salts, caustic soda, and hydrochloric acid.
●Salt Harvesting
Most salt harvesting processes leave little brine behind, but any liquids left after evaporation are highly concentrated and need secure storage until the next batch of brine is added.
●Hydraulic Fracturing
In hydraulic fracturing, fracking fluids are injected deep underground to crack bedrock and open routes to withdraw formerly isolated pockets of oil and natural gas. During this process, fracking fluids mix with brine from deep underground salt deposits. When the fracking fluid is withdrawn, the mixture, known as produced water, requires special handling, even if just for storage until the liquid is reused for another round of fracking.
●Natural Gas Mining and Storage
Salt caverns are preferred storage locations for natural gas, and brine is produced when water is used to excavate them to usable proportions. This brine can then be reused for retrieving the stored gas, but only if it has been properly stored in a brine pond.
●Power Plant Cooling Towers:
Power plants rely on highly purified and distilled water for cooling purposes. During the distillation process, a tiny amount of concentrated wastewater is left behind from each gallon. Since each cooling tower requires millions of gallons of water, even a tiny amount of residual adds up. The wastewater tends to include a high amount of salt, which must be processed further or stored.
●Chlor-Alkali Products
The creation of caustic soda, soda ash, and chlorine all generate thousands of gallons of caustic brine as a waste product. The hazardous liquid requires secure storage to prevent spills or accidental exposure before further filtration is applied.
What is Brine Mining?
Brine ponds are widely used in brine mining, which is the technical term for harvesting minerals dissolved in water through evaporation. Salt from ocean water is one of the most common minerals mined this way, but there are many other valuable minerals to harvest, whether from underground water deposits, the ocean, or as a byproduct of industrial processes. Lithium, for example, is most commonly found in naturally occurring underground brine pools and is widely harvested through this method.
An important distinction between brine mining and solution mining or leaching is that the minerals in brine-mining are already dissolved, while the latter examples are found in a solid state and are purposely dissolved with water or chemicals.
Aside from salt and lithium, bromine, calcium, iodine, lithium, magnesium, potassium, and other minerals are harvested from brine pools. In addition to being a valuable source of these minerals, brine mining is an important element of waste minimization and resource recovery goals.
