The exploitation of salt resources encompasses a diverse array of extraction methodologies, each tailored to specific environmental and industrial requirements. These methods range from solution mining techniques, where dissolved minerals are extracted from brine solutions through hydraulic pressure or natural seepage, to large-scale solar evaporation processes that utilize shallow ponds to gradually concentrate seawater or brine under the sun’s heat until crystalline salt deposits form. Additionally, mechanical evaporation methods employ energy-intensive equipment such as vacuum pans or rotary dryers to accelerate the removal of water from salt solutions, particularly in regions where climatic conditions limit solar-based operations. Advanced hybrid systems may even integrate these approaches, combining controlled evaporation basins with centrifugal desiccation technologies to optimize yield and purity. Each extraction phase—from initial brine extraction through intermediate concentration stages to the final granular or flake salt product—requires precise control of factors like temperature, humidity, and mineral composition to ensure consistent quality in the final dry product. Modern industrial applications often prioritize eco-friendly closed-loop systems to minimize water consumption and environmental impact during these multi-stage processes.
The exploitation of the salt resources involves different methods of extraction; from its minerals in diluted form, dry extraction or evaporation of seawater until the dry product is obtained.
First and foremost, one of the primary methods of salt procurement involves the extraction of rock salt (halite), which exists in vast solid-state deposits formed through geological processes over millennia. These subterranean salt formations originate from the evaporation of ancient inland seas or enclosed marine basins, followed by tectonic movements and sedimentation that buried these mineral-rich layers beneath strata of rock and sediment. Such deposits vary widely in accessibility: some lie near the Earth’s surface as exposed salt domes or outcrops, while others are buried at considerable depths due to geological upheavals, requiring advanced drilling techniques to access. For instance, salt diapirs—upward-pushing columns of salt—commonly found in regions like the Gulf Coast of North America or the Zagros Mountains of Iran, exemplify such formations shaped by prolonged pressure and crustal dynamics.
The extraction of subsurface rock salt typically employs two principal methods: conventional underground mining using tunneling and blasting for deep deposits, or solution mining where freshwater is injected into saline aquifers to dissolve the salt, creating brine that is pumped to the surface. Large-scale operations may deploy rotary drills equipped with diamond-tipped bits to penetrate dense salt beds, followed by mechanical conveyors or hydraulic fracturing systems to remove the excavated material. Surface-level deposits, meanwhile, are often extracted via open-pit mining, utilizing excavators and bulldozers to quarry the mineral efficiently.
Post-extraction, the raw rock salt undergoes rigorous processing to meet industrial specifications. The material is first crushed in jaw crushers or impact mills to reduce large blocks into smaller grains, followed by screening through vibratory separators with mesh sizes calibrated to desired granulation (e.g., 1–3 mm for road de-icing salt or finer particles for food-grade purification). The crushed salt is then subjected to washing with purified water to remove clay and organic impurities, after which it is dried in rotary kilns or fluidized bed dryers to eliminate residual moisture. Chemical analysis via X-ray fluorescence (XRF) or ion chromatography determines the mineral’s purity and elemental composition, enabling categorization for specific end uses:
Edible salt: Requires >97% NaCl purity, with controlled additive iodization.
Chemical-grade salt: Demands >99.5% purity for chlorine production in chlor-alkali plants.
De-icing salt: Tolerates lower purity (≈90% NaCl) but must resist caking in humid conditions.
Brine-based products: Further processed into sodium hydroxide, chlorine gas, or caustic soda via electrolysis.
Modern operations increasingly incorporate sustainability measures, such as recirculating brine effluent and rehabilitating mined land, to mitigate environmental footprints. Additionally, automated sensors and IoT-enabled machinery now optimize energy usage in crushing and drying phases, aligning with industry trends toward precision resource management.
Secondly, there is the soultion mining. When a salt deposit cannot be economically mined conventionally, this method is used to make the salt appear in liquid form. The brine generally goes to a vacuum evaporator to produce the final product. It can be found in underground places, as well as in shallow lakes.
This method yields a very high purity NaCl, fine in texture, and it used in those applications requiring the highest quality salt such as chemical applications.
The vacuum process consists of pumping the salt brine into a series of vacuum pans, very huge and closed, and by pressure and energy the brine is boiled thus forcing the crystallization of the salt. This process requires a very high energy consumption.
Lastly, the solar evaporation is the oldest method for producing salt. Also, salt accounts for about 3.5 percent of the world’s oceans. It is naturally produced when seawater is introduced to a series of ponds for its continued evaporation and finally for the fractional crystallization of the different salts, until the precipitation of the Sodium Chloride in the ponds called crystallizers. After that, the salt is harvested and processed depending on its requirements.
Furthermore, solar evaporation fields are located in areas where climate conditions are optimal. High evaporation rates, minimal precipitation and steady winds are key-climate factors for having a high production yield.
WUXI rising has a huge expertise in design solar saltworks from scratch and remodeling existing ones thus increasing efficiency and productivity, offering complete studies from conceptual design to site selection, production model, bitterns’ management, financial analysis, and biological studies.
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