Refining- Need and Process
Salt is an essential ingredient for the survival of all living creatures, including humans. Salt is needed in regulating the fluid balance or water content of body. Salt cravings may occur as a result of trace mineral deficiencies or due to the deficiency of sodium chloride itself. Salt is important for life, but its overconsumption can cause health problems, such as high blood pressure, in those individuals who are genetically predisposed to hypertension. Main source of salt is rocks and sea. Maximum consumption of salt is in its natural form after being produced from sea or directly from rock. But with time, awareness about the use of salt have grown manifold and the demand for refined iodized salt has increased tremendously over the last few years. We offer end to end solutions for the refining of natural sea and rock salt.

Refining can be defined as the cleaning, crystallization, iodizing and sizing of salt.
It not only helps in increasing the purity of salt but also improves flow-ability and use of anti-caking agents helps in keeping quality too. During refining and drying process iodisation is done which is important for human body to avoid various diseases. Refined salt is further graded for various applications like kitchen salt, table salt and industrial salt.
The different processes and stages involved in salt processing machinery for the refining of salt are:

• Salt feeding
• Salt washing & milling
• Centrifuging
• Dosing of additives & coating
• Salt drying
• Sizing and conditioning
• Storing
• Packaging

The main objective of any salt iodization and refining program is to make sure that the salt contains the prescribed amount of iodine and other minerals at the time of consumption. Refining and salt iodization are considered as the most effective long-term public health program for achieving optimal iodine nutrition. It also helps in sustainable elimination of the iodine deficiency disorders, including - retarded mental and physical development, hypothyroidism, endemic goitre, reproductive failure and childhood mortality.

Process
SSP has developed two basic process for refining of salt

• Mechanical Iodised Salt Refinery
• Vacuum Iodised Salt Refinery

The physical characteristics and chemical composition of salt can vary, which depends upon the composition of the raw material and the process of manufacturing. These features are given in the table below for commonly used varieties of salt.

Processes for refining salt
Refined salt is high in purity (NaCl content 99.5%), dry, and white with uniform grain size (0.3 - mm). Depending on the application, it is sold with or without additives such as:

1. Anti-caking agents:
   To prevent the adjacent grains from cementing together to form a hard solid mass; the widely agents are potassium or sodium ferrocyanide in the range 5-15 parts per million.
   
   
2. Free Flowing Agents:
   To provide the crystals with a mechanical coating, which acts as a lubricant and absorbs any water vapor within the package after sealing; some widely used free flowing agents are magnesium carbonate,calcium silicate, sodium silico-aluminate and tricalcium phosphate.
   
   
3. Iodizing agents:
   To control disorders due to iodine deficiency, commonly used agents are potassium iodide or iodate at a level of 30-170 ppm.