Salt Types, Applications & Manufacturing Processes
Salt comes in various forms from solar salt, which is the most common, to pellets and mini cube for high purity applications. Solar salt in the United States is mainly produced at the Great Salt Lake in Utah. Deicing salt includes rock salt and calcium chloride, which is used on sidewalks, parking lots, and driveways. The main difference in deicing salt products is the effective temperature range at which it should be applied. Below, we will go over the different types of salt, how and when to use the various salt products, and how the salt is produced.
Solar Salt Products
At the Robert B. Hill Co., we get our solar salt from the Great Salt Lake in Utah. The salt is delivered via rail car, which allows us to purchase in large quantities and reduce the possibility of shortages. We bag our solar salt in two different sizes:
- 50 lbs. Solar Salt Bags
- 80 lbs. Solar Salt Bags
We also deliver Neusalt, which is solar salt delivered in bulk by our revolutionary process. Neusalt is typically delivered pneumatically via specialized equipment that is installed in your facility in quantities of 2,000 to 10,000 lbs.
Solar Salt Manufacturing/Harvesting Process
Commercial solar salt is produced by natural evaporation of seawater or brine in large, diked, earthen concentration ponds called condensers. Seawater averages about 3.5% NaCl (salty lakes like the Dead Sea and the Great Salt Lake can be much higher) when it enters the condensers. Climate is very important in solar salt production. The sun and wind provide the energy to evaporate the water and raise the salt concentration to the point of crystallization, 25.8% NaCl (25.4o Bé).
As the water concentrates, calcium carbonate is the first chemical to crystallize. By moving the increasingly-saline brine through a series of ponds, sometimes over a period that can be as long as two years, the calcium carbonate is thus removed from the final salt product. When the concentration has increased to the most favorable crystallizing level, 26o Bé, the brine is introduced into the crystallizing ponds.
As salt crystallization proceeds, the concentration continues to increase. At 29 or 30o Bé, between 72% and 79% of the total salt has been crystallized. If proper brine control is performed during concentration and crystallization, it will result in salt of purity of >99.7% NaCl. Typical purity is 99.9%.The crystallizing pond is then drained of the remaining highly concentrated magnesium brine (called “bitterns” because of its taste) which are either discharged or further processed for other minerals. Mobile harvester equipment then strips the newly-deposited layer of salt crystals, and they are washed (in clean brine to prevent loss), crushed and sometimes dried in kilns or fluidized-beds driers.
Pellet salt is a higher purity salt than solar salt. It comes in an oval/egg like shape. It reduces the chance that bridging will occur in your brine tank and is typically used in applications that require higher purity such as hospitals, food plants, and various other applications. We deliver pellet salt in 50 lb. plastic bags. Pellet salt typically has a purity of 99.87%. It is vacuum pan salt produced by industry standard solution mining and evaporation process. The salt is washed, filtered, dried, screened, pressed into pellets, admixed, and quality control tested.
Mini Cube Salt
Mini cube salt comes in small square blocks and has an even higher purity than pellet salt at 99.89%. The main application for mini cube salt is in the medical industry, circuit board manufacturing, and for water softeners that supply water to industrial and commercial reverse osmosis systems as well as deionization systems. It is vacuum pan salt produced by industry standard solution mining and evaporation process. The salt is washed, filtered, dried, screened, admixed, compacted into sheets, and quality control tested.
Special Purity Salt (Food Grade)
Special purity salt can be used in the process of manufacturing food and also in residential and commercial pools. The high purity of food grade salt removes almost all impurities and is the same as table salt that you purchase at the grocery store. We delivery special purity granulated food grade salt in 50 lb. bags. The food grade salt is vacuum pan salt produced by industry standard solution mining and evaporation process. The salt is washed, filtered, dried, screened, and quality control tested.
Rock Salt (De-icing Salt)
Rock salt is the most common deicing product used for roads, sidewalks, and driveways. Rock salt is relatively inexpensive and does a good job at reducing ice build-up. The draw backs of using rock salt are the high levels of dirt that are included with the salt, and effective temperature is only zero to 10 degrees Fahrenheit. We deliver rock salt in 50 lb. bags.
Extraction Process and Salt Mining
Rock salt is mined from underground deposits by drilling and blasting. Deposits are reached through a circular shaft, typically about 20 feet in diameter and as deep as 2,000 feet, depending on the depth and location of the salt deposit.
Shafts are lined with concrete, at least through the overburden and into the top of the salt deposit, and often all the way to the shaft bottom.
Mining methods depend on whether the salt is configured as a relatively horizontal sedimentary deposit or a more vertical salt dome. The differences in mining methods depend on the thickness and structure of the salt deposit. Bedded or layered deposits are mined using the room and pillar mining method, as horizontal rooms or entries of about 10-25 feet high and 50 feet wide. Openings or cross-cuts are created perpendicular to the length of the rooms to connect the rooms at planned intervals. Salt pillars are left in place to provide structural support for the overlying roof and other layers. Most room-and-pillar mines recover about 45-65% of the salt available, with the remainder left behind as pillar supports with margins both above and below the mined area. Each day, based on production needs, several rooms are blasted, each blast bringing down 350-900 tons.
In salt domes, after a level of room-and-pillar extraction is completed, the usual practice is to “bench” the mine by drilling and blasting the floor extending the excavation downward and removing vast quantities with each blast.
Typically salt is mined using large, diesel-powered equipment designed for undercutting, drilling, blasting, loading and transporting the blasted salt.
Diesel-powered trucks take the salt freed by blasting to a system of crushers and conveyor belts, and ultimately, to the hoist or “skip.” Sometimes the salt is stockpiled in the mine where it awaits hoisting; other operations maintain surface storage stockpiles. Each skip can lift 18-20 tons of salt, and they move quickly. A large mine may be able to hoist up to 900 tons an hour.
Calcium Chloride is the most effective deicing product used for roads, sidewalks, and driveways. The only drawback to using calcium chloride is the cost. It is much more expensive than rock salt but has a lower effective temperature of up to minus 25 degrees Fahrenheit. We deliver calcium chloride in 50 lb. bags.