Grainer salt

There are three important methods of salt isolation and purification brine solution, rock salt mining, and the open pan or grainer process. The percentages of these methods have not changed dramatically in the last few years and are 54% brine, 32% rock salt, and 14% grainer salt. 

Hot brine solution is held in an open pan approximately 4-6 m wide, 45-60 m long, and 60 cm deep at 96°C. Flat, pure sodium chloride crystals form on the surface and fall to the bottom. The crystals are raked to a centrifuge, separated from the brine, and dried. A purity of 99.98% is obtained. Grainer salt dissolves more readily and is preferred in some applications, such as the butter and cheese industries. It is more expensive because of energy use for the hot brine. Its cost can be as much as six times that of rock salt and 20 times that of brine. 

Grainer salt is made by surface evaporation of brine in flat pans open to the atmosphere. Heat usually is furnished by steam pipes located a few inches below tlie tank bottom. Crystals form at the surface of the brine and are held tliere temporarily by surface tension. Thus, they grow laterally for awhile and form thin flakes. But, as they grow, they tend to sink and this process imparts a peculiar, hollow pyramid-like structure to them. Such crystals are called hopper crystals. Ultimately, the crystals sink to the bottom where they are scraped to one end of the pan. The crystals are fragile and during handling they break up, finally assuming a flake-like shape. Thus, tlie term flake salt. 

Sodium chloride (salt, common salt, rock salt, and grainer salt) is a naturally occurring mineral. 

R.B. Richards, Grainer Salt. In D.S. Kaufmann (ed.), Sodium Chloride, ACS Monograph 145, Reinhold Publishing Corp., New York (1960), p. 262. 

There are three methods of salt production and purification brine solution, rock salt mining, and the open pan or grainer process. 

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