Potassium nitrate is anhydrous white powder and does not deliquescence in air. Sometimes it is light gray with impurities. The melting temperature is 2.11g/cm3 at 334℃, and decomposes to potassium nitrite and oxygen at 338℃ or above. The solubility of potassium nitrate decreases with the increase of nitric acid concentration, and increases when the minimum value is reached, and the solubility of potassium nitrate in water increases with the increase of temperature. The pure product contains 46.58% potassium oxide and 13.85% nitrogen. Potassium nitrate is readily soluble in water, and the solubility increases sharply with the increase of temperature. At 20 ℃, 31.2 grams of water can be dissolved in 100 grams of water, and 247 grams can be dissolved at 100℃.

Production process
1 neutralization method
This method neutralizes potassium nitrate and water by neutralization of nitric acid and potassium hydroxide.
2 ammonium nitrate conversion method (complex decomposition method)
Ammonium nitrate and potassium chloride are decomposed to produce potassium nitrate. The by-product is ammonium chloride.
3 ion exchange method
By using ion exchange resin or zeolite, potassium chloride and nitrate are used as raw materials and the cation exchange resin has a very close adsorbability to potassium ammonium ion. By the effect of cation exchange resin, potassium ammonium chloride and nitrate solution in the solution of potassium chloride and nitrate are converted to each other in the ion exchange resin, and potassium nitrate solution is obtained.

Application
1, used as analytical reagent and oxidant, and also for the synthesis and preparation of potassium salts.
2. In the food industry, they are used as chromogenic agents, color protecting agents, antimicrobials and preservatives, such as salted meat, to play an antiseptic role in luncheon meat.
3, it is the raw material for making black gunpowder, such as mine propellant, fuse and firecracker. It is also used for fireworks to produce purple sparks. Mechanical heat treatment is used as a quenched salt bath. Ceramic industry is used in the manufacture of enamel color drugs. Used as a glass clarifier. It is used for making automobile lamp glass shell, optical glass picture tube glass shell and so on. The pharmaceutical industry is used for the production of penicillin potassium salt, rifampicin. It is used for making cigarette paper. Used as a catalyst. Ore dressing agent. A compound fertilizer used as a crop and a flower.
4. Potassium nitrate is also the chromogenic agent permitted in China. It is reduced to potassium nitrite in meat products due to bacterial action, which plays a role in protecting color and bacteriostatic. China stipulates that it can be used for meat products. The maximum usage is 0.5g/kg, and the residue should not exceed 0.03g/kg.
5. It is used for making pyrotechnics, matches, ceramic glaze, fertilizer and so on.
6, industrial potassium nitrate is also widely used in strengthening glass manufacturing process.
Attentions
Operational considerations: airtight operation and ventilation enhancement.  Operators must undergo special training and strictly abide by the rules of operation. It is suggested that the operator wear a hood type electric air supply filter respirator, wear polyethylene protective clothing and neoprene gloves. Keep away from fire and heat sources. Smoking is strictly prohibited in the workplace. Away from flammable and combustible materials. Avoid producing dust. Avoid contact with reducing agents, acids and active metal powders. Light handling and unloading should be carried out to prevent packing and container damage. Equipped with corresponding varieties and quantities of fire fighting equipment and leakage emergency handling equipment. The empty container may remain harmful.
Storage precautions: store in a cool, dry, well ventilated storehouse. Stay away from fire and heat. The temperature of the library is not more than 30 C, and the relative humidity is not more than 80%. It should be stored separately with reducing agent, acid, easy or combustible material and active metal powder. The storage area should be equipped with suitable material for leakage..