What are the uses and methods of using sodium cyanide?

Release time:

26-02-05

Source:

Sodium cyanide (NaCN) is a highly toxic but industrially valuable chemical widely used in many fields. Despite its extreme hazards, it remains an indispensable raw material in many industrial processes under strict control and standardized operation.

I. Main Uses

1. Precious Metal Extraction (Gold and Silver Smelting) The core application of sodium cyanide is in the mining industry for extracting precious metals such as gold and silver. It can form soluble cyano complexes (such as [Au(CN)₂]⁻) with gold and silver in the presence of oxygen, thereby dissolving the metals from the ore. The metals can then be recovered through activated carbon adsorption or zinc powder replacement.

2. Electroplating Industry Sodium cyanide is widely used in electroplating as a powerful complexing agent for copper, silver, cadmium, and alloy plating (such as brass and imitation gold plating). It can form stable complexes with metal ions, controlling the deposition rate and avoiding problems such as loose, porous, or poorly adhered plating layers. For example, in the silver plating process, sodium cyanide can prevent silver ions from being reduced too quickly, ensuring a uniform and bright plating layer.

3. Organic Synthesis and Chemical Raw Materials Sodium cyanide is a starting material for many organic compounds, used in the synthesis of:

Pharmaceuticals: intermediates for drugs such as penicillin, vitamin B6, folic acid, acyclovir, gabapentin, and pregabalin;
Pesticides: glyphosate, cypermethrin, paraquat, and penflusulfonium;
Dyes and Fragrances: indigo, fluorescent whitening agent VBL, and diethyl malonate, a raw material for fruit-type fragrances;
Plastics and Rubber: synthesis of acrylonitrile and nitrile rubber.

4. Metal Heat Treatment:

Heat treatment processes such as quenching, carburizing, and nitriding are used for steel parts. These processes can improve the surface hardness, wear resistance, and fatigue strength of metals.
They are suitable for the final treatment of precision mechanical parts (such as gears, shafts, measuring tools, etc.).

5. Other industrial uses:

As a masking agent or complexing agent in chemical analysis;
used for engraving and etching glass and quartz;
used to manufacture other cyanides (such as potassium cyanide, sodium thiocyanate, sodium thiocyanate, etc.)

II. Usage Methods and Operating Procedures

Because sodium cyanide is highly toxic (even a trace amount can be fatal), its use must be carried out in a professional, enclosed, and well-ventilated environment, and in strict accordance with safety procedures:

1. Operating Environment Requirements

Operations must be performed in fume hoods or closed systems; they are strictly prohibited in open spaces or densely populated areas.
Workplaces must display warning signs such as “Highly Toxic” and “No Smoking,” and eating and smoking are prohibited.

2. Weighing and Sampling

Use dedicated tools and avoid mixing with other chemicals;
A balance is recommended for weighing to prevent powder from flying;
Handle gently to avoid dust or skin contact.

3. Dissolution and Reaction

When dissolving, sodium cyanide should be added to water slowly. It is strictly forbidden to pour water into sodium cyanide to prevent violent reaction and splashing.
Avoid splashing during stirring and ensure operation under alkaline conditions to prevent the generation of highly toxic hydrogen cyanide gas (HCN).

4. Material Transfer

For solid transfers, use sealed containers; for liquid transfers, use alkali-resistant pumps or siphons.
Avoid spills. In case of leakage, immediately treat with oxidants such as sodium hypochlorite or bleaching powder to decompose it into less toxic substances.

5. Personal Protective Equipment

Wear a gas mask, corrosion-resistant gloves (such as fluororubber), and protective clothing;
immediately after operation, rinse exposed skin with plenty of water and thoroughly clean hands with soap.

6. Emergency Treatment

Equip with eyewash stations and emergency showers;
Antidotes such as amyl nitrite and sodium thiosulfate should be available on site and used immediately after poisoning.

III. Safety Warnings and Alternative Trends

In recent years, the industry has been actively developing cyanide-free electroplating technologies to reduce risks. For example, Changshan enterprises have made breakthroughs in non-toxic alternative technologies, promoting the development of green electroplating.
Although alternative processes are gradually being promoted, sodium cyanide is still difficult to completely replace in high-requirement electroplating and gold smelting fields.

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What are the uses and methods of using sodium cyanide?