For the extraction of gold and silver from ores; gold (or silver) reacts with sodium cyanide in the presence of air to form the complex sodium cyanurate, which dissolves the gold from the ore. Further reaction with zinc can displace gold, generating sodium cyanate and free the gold out.
4Au + 8NaCN + O2 + 2H2O → 4Na [Au (CN) 2] + 4NaOH
Na [Au (CN) 2] + Zn → Na [Zn (CN) 3] + Au
Others can also be used for iron blue (intermediate sodium ferrocyanide production), cyanuric chloride (intermediate product of cyanide production), plating bath (copper, cadmium and other plating, DL-methionine synthesis). It can act as liquid steel carburizing agent with barium chloride (usually accompanied with a bath temperature of 800 °C or more; should add salts that don’t cause NaCN evaporation at high temperature) , and for pesticides and other purposes.
White crystal; Formula NaCN; Molecular weight: 49.02; Melting point 564 ℃; Boiling point 1469 ℃; Vapor pressure 1.0mmHg (817 ℃). Soluble in water, slightly soluble in ethanol; for the extraction of gold and silver ore, copper, zinc, carburizing, medicine and so on. For metallurgy, steel quenching, electroplating, extraction (forming cyanide), organic synthesis of raw materials, insecticidal and anti-corrosion.
Sodium cyanide binds to the ferric iron of oxidized cytochrome oxidase, disabling its ability to deliver oxygen, resulting in tissue hypoxia, "intracellular asphyxia." Rat: oral administration-LD50: 6.44mg / kg, adult lethal dose 200mg. Being highly toxic.
It can be absorbed through the respiratory tract, digestive tract and skin. Animals, after inhaling sodium cyanide aerosol of 40mg-90mg / m3, get symptoms of irritations, irritability and salivation after 25 to 43 minutes. Inhalation of 150mg ~ 170mg / m3 for 62 to 76 minutes or inhalation of 400mg ~ 500mg / m3 for 20 minutes can cause death. Human oral LD50 is about 1mg ~ 2mg / kg. Under normal conditions of production, sodium cyanide dust is often inhaled at room temperature, and sodium vapor can be inhaled during heat treatment. Misdiagnosis is also one of the common causes of poisoning. In the event of a fire, try to prevent the generation of toxic hydrogen cyanide gas. Do not use carbon dioxide or acid-base foam fire extinguishers. Fire-fighting operation personnel must wear protective equipment, try not to contact with water containing sodium cyanide. This product is toxic with poisoning causing dizziness and other uncomfortable symptoms. When found, patients should immediately leave the contaminated area to the fresh air and taken 1% soda solution as first aid, at the same time, go to the hospital for treatment. UN No.: 1689/6257 / 6.1-04 / 215.
Air & Water Reactions
Slowly evolves flammable and poisonous hydrogen cyanide gas.
NaCN is a white crystalline solid that is odourless when dry but emits a slight odour of HCN in damp air. It is slightly soluble in ethanol and formamide. It is very poisonous. It explodes if melted with nitrite or chlorate at about 450°F. It produces a violent reaction with magnesium, nitrites, nitrates, and nitric acid. On contact with acid, acid fumes, water, or steam, it will produce toxic and flammable vapours.
Sodium cyanide is weakly basic. Reacts with acids of all kinds to generate quantities of very poisonous hydrogen cyanide gas. Incompatible with strong oxidizing agents, especially if solution dries out. Gives insoluble products with silver(I), mercury(I) and lead(II) ions that may decompose violently under certain conditions.
Extracting gold and silver from ores; electroplating baths; case hardening steel by liquid nitriding; manufacture of hydrocyanic acid and other cyanides.
1.(Castner improved method) sodium metal and ammonia as raw material to generate sodium amide, and then subjects to carbon reduction at 700 ~ 800 ℃to obtain the product .
2Na + 2NH3 → 2NaNH2 + H2
NaNH2 + C →  + H2
2. Natural gas (methane), ammonia, air as raw materials; their mixture is passed through the catalyst bed at 1000 ℃to generate hydrogen cyanide, followed by reaction with sodium hydroxide to obtain it .
HCN + NaOH →  + H2O
3. Hydrogen cyanide can obtained as byproduct during ammonia oxidation of propylene to generate acrylonitrile .
A clear colorless aqueous solution.