Sodium chloride

Brief Overview

Industrial salt, also known as sodium chloride, has a formula of NaCl. It is an ionic salt and exists as white crystals. Sodium chloride is characterized for its salinity and can be found as a major component in edible salt. It is often added to food as a condiment and serves as a food preservative. In a solid sodium chloride crystal lattice, the sodium cations and chloride anions are arranged in a face-centered cubic structure, with each ion surrounded by 6 other oppositely charged ions.

The thermal conductivity of sodium chloride decreases with increasing temperature and also decreases with doping. Sodium cations are metallic conductors and when temperature increases, the thermal population of higher energy levels in the molecular orbits are expected to bring about an increase in conductivity. However, thermal vibrations of the nuclei produce electrical resistance and this effect is sufficiently enhanced at higher temperature, resulting in a decrease in conductivity of the metal at higher temperature.

Manufacturing Process

Mining

Sodium chloride occurs naturally and is abundant in nature as mineral, halite. They can be mined and this is done by pumping water into mines to dissolve the rock salt and the water is then allowed to evaporate. Upon evaporation, sodium chloride crystals will precipitate out, hence isolated and collected for further processing. They will then be processed, purified and standardized for industrial consumption.

Evaporation of Seawater

Sodium chloride also exists as a mixed evaporates in salt lakes. Using brine, these sodium chloride solutions are allowed to evaporate and some impurities are deposited. Saturated brine is then passed through a series of recrystallization ponds where sodium chloride salt will crystallize out. The crystals are isolated, further purified using crystallization, processed and standardized for industrial consumption.

Food Industry

It is employed as an additive in livestock feed. Salt is added to food, either by the food producer or by the consumer, as a flavor enhancer, preservative, binder, fermentation-control additive, texture-control agent and color developer. The salt consumption in the food industry is subdivided, in descending order of consumption, into other food processing, meat packers, canning, baking, dairy and grain mill products. Salt is added to promote color development in bacon, ham and other processed meat products. As a preservative, salt inhibits the growth of bacteria. Salt acts as a binder in sausages to form a binding gel made up of meat, fat, and moisture. Salt also acts as a flavor enhancer and as a tenderizer.

Other Applications

Sodium chloride is used in manufacturing of pharmaceuticals, solar ponds, buna, neoprene and white rubber types. It is also used in deicing for roads and as an anti-icing agent. In addition, it is used in oil drilling in gas and oil exploration and as a major source of sodium cations and chloride anions in feedstock for chemical synthesis. Sodium chloride is used as a brine, rinse in textile processing to separate organic contaminants and help with salt out of dyestuffs precipitate. Dyes are generally negatively charged and they get absorbed to the positively charged sodium cations readily. They will form insoluble compounds and eventually precipitate out, allowing easy removal and isolation. It is also used to blend with concentrated dyes to standardize them. In addition, it is employed to manufacture FMCG products such as detergents, soaps and shampoos.