Salt is sometimes crystallized to produce flake-shaped grains which have a unique texture or intensity of flavor. Some are ground coarsely to produce a burst of saltiness as they are crushed between your teeth. Some are ground finely so that they dissolve quickly, season uniformly, or coat the parts of a food particle that is most likely to touch your tongue.
There is more to salt than one might imagine. Some salts are enhanced with spices, flavoring, or color to produce a special dining experience. If you are purchasing a packaged product, check the description and ingredients to learn fascinating facts about the salt. Some black cooking and table salts contain small amounts of activated charcoal which produce a flavor that many people enjoy.
Pink salts are the most popular. Their color is often natural and caused by trace amounts of iron or another element included in the salt.
Some have been artificially colored by people. Salt Production Methods: The pie diagram above shows the approximate amount of rock salt and rock salt equivalent produced in the United States during the calendar year Data from the United States Geological Survey. In about 39 million tons of salt were produced in the United States. There are four important categories of rock salt production:. The United States consumes more salt than it produces. To satisfy demand in , about 16 million tons of salt were imported.
The amount of imported salt has been increasing in the past few decades. This is mostly a result of increasing demand in the United States and lower production costs in other countries. Salt Core: Photograph of a short segment of a salt core, obtained by drilling a well down to a subsurface salt layer and retrieving a cylinder of the salt. A core of the entire salt layer is often obtained and brought to the surface for examination by a geologist, and for chemical and physical testing.
The properties of numerous salt cores will be used to determine which portion of the rock layer will be mined. Companies interested in developing a salt resource located hundreds to thousands of feet below the surface usually drill numerous wells down to and through the salt layer.
They drill to learn the thickness of the salt and what types of rocks enclose it. They also obtain core samples of the salt see accompanying photo that will be used to determine its chemical and mineral composition. The purity of the salt determines how it can be used. The depth determines the cost to build the mine. Depth also determines the electricity costs of operation, ventilation, and lifting salt, equipment, people, and water in and out of the mine.
Most of the rock salt produced in the United States is produced by traditional room and pillar mining - a mining method that is widely employed in mining for coal. This involves sending people and machines underground to remove the salt.
The salt is usually hundreds of feet below Earth's surface. To start the mine, a large-diameter shaft is drilled vertically down to the salt layer.
That shaft will be equipped with lifts, much like elevators, that will be used to lower equipment, people, and supplies down to the level of the salt. Other shafts will be built down to the salt. Some of these shafts will be used to lift the mined salt up to the surface. Others will be used to bring fresh air into the mine or exhaust mine air to the surface.
Continuous Mining Machine: The machine in the photo above is a continuous miner in a salt mine. The cutting head on the right side of the photo is a rotating drum equipped with durable cutting points. As the drum rotates, the cutting head grinds the salt into small pieces which fall onto a pan directly below.
Once they have been lowered down a shaft to the level of the salt, the mining machines will begin cutting underground tunnels through the salt. A large cylindrical drum with cutting picks is mounted on the front of the mining machine. This drum rotates and cuts its way through the salt see accompanying photo. As a mining machine cuts its way through the salt, broken pieces of salt fall onto a large metal pan mounted immediately below the rotating cutting drum. Mechanized arms rake the salt up the pan and onto a conveyor that carries the salt to a waiting wagon or to a mobile conveyor system.
The conveyor will transport the salt to a mine shaft, where the salt will be lifted to the surface, or to an underground storage area. This is the basic process of underground salt mining with a continuous mining machine. Solution mining of salt is done by injecting hot water under pressure down a well into a subsurface layer of rock salt. That same water is then withdrawn up to the surface through a nearby recovery well. While the water travels through the layer of rock salt - from the injection well to the recovery well - it dissolves a significant amount of salt.
The water is returned to the surface as a concentrated salt solution known as "brine". Most solution mining sites in the United States are operated by chemical companies who use the brine as a feedstock at a chemical manufacturing plant a short distance from the recovery well. A few solution mining sites have ponds at the surface where they produce solar salt. Others use heat or a vacuum heating process to recrystallize the salt.
These recrystallized salts have a higher purity than salt mined from the same rock unit. The recrystallized salt is a higher quality and higher purity because insoluble mineral matter and other insoluble impurities were left in the ground. Vacuum Pan Crystallizers: Six vacuum pan crystallizers connected in a series. They are approximately 30 feet in height.
These crystallizers are in a sugar plant, but similar units are used in salt crystallization. Vacuum pan salt is produced in large enclosed tanks known as vacuum pans or vacuum salt crystallizers. The tanks are filled with brine, which is heated by injecting steam into the tank. The steam heats the brine and causes it to boil. As the brine boils it produces additional steam, which is fed into a second vacuum pan and causes its water to boil. Three or more vacuum pans are connected in a series to make efficient use of the steam.
As the brine in the tanks becomes saturated with salt, crystals of salt begin to form in the tanks. Salt produced in a vacuum pan has a much higher purity than salt produced from an underground mine. Vacuum pan salt is usually made from brine produced by solution mining.
When the salt was dissolved underground, solid particle impurities in the salt were not dissolved and remained underground. Vacuum pan salt also has a different texture - its crystals are very small. England was covered by inland seas over million years ago which helped create the layers of salt that are mined today.
When very hot temperatures in the area evaporated the waters very slowly, they left large salt deposits under the earth. In the UK as the water evaporated and the salt crystals started to form they got their brownish colour from sand blown in from eastern deserts. However other geological influences mean the rock salt's colour can sometimes go from clear, to pink, to dark brown. Most of the rock salt used for gritting roads in the UK comes from mines of ancient underground salt deposits in Cleveland, County Antrim and Winsford.
Winsford is in Cheshire and four of the surrounding towns - Middlewich, Nantwich, Northwich and Leftwich are all historically related to salt production.
The " wich " or sometimes "wych" in their name is often associated with brine springs or wells. The Salt Association who are the trade body for salt producers, estimate that the UK's salt mines to have about km miles of tunnels. If you thought stocks would be depleted any time soon you'll be surprised to learn that the proven UK salt reserves are extensive, with an estimated years capacity at current extraction rates. The primary difference between rock salt and ordinary table salt is the size and colour.
Rock salt forms in very large, chunky crystals, as opposed to the small crystals seen in table salt. Like table salt, rock salt also has an assortment of trace minerals which can have an impact on how it behaves chemically.
The large crystal size of rock salt means it is not usually used in cooking as it takes too long to dissolve. This site uses Akismet to reduce spam. Learn how your comment data is processed.
Purification process For this reason, rock salt must undergo a purification process, or be separated from less pure forms before it may be consumed. Sources for rock salt Rock salt does not always form from ancient lakes.
Share on Twitter Share on LinkedIn. Go to our next article Check our previous article. Leave a Reply Cancel reply Your email address will not be published. Enquire now - Contact us Give us a call or fill in the form below and we will contact you.
0コメント