Advanced Cyanide Neutralization Technologies: Ensuring Safety in Modern Mining

Cyanide-containing wastewater requires careful management, and numerous treatment methods have been developed to address this challenge. These include alkali chlorination, acidification recovery, sulfur dioxide-air oxidation, electrochemical methods, activated carbon adsorption catalytic oxidation, peroxide oxidation, ferrous sulfide oxidation, biochemical methods, ion exchange, natural purification, ozone oxidation, emulsion liquid membrane techniques, and pressurized hydrolysis. Below is a detailed overview of primary treatment methods for cyanide and cyanide tailings, along with insights into the safety of cyanide use in mining.

1. Chemical Treatment

1.1 Alkali Chlorination Method

The alkali chlorination method is highly effective for treating high-concentration cyanide wastewater, offering remarkable results with user-friendly equipment suitable for both small-scale batch processes and large-scale operations. This approach has proven successful for enterprises managing cyanide waste.

Reaction Principle:
Under alkaline conditions, bleaching powder (primarily calcium hypochlorite, Ca(ClO)₂) oxidizes cyanide ions (CN⁻) in solution. The process occurs in two stages:

1. CN⁻ is first oxidized to cyanate (CNO⁻), which is far less toxic (approximately 0.1% of cyanide’s toxicity).
2. CNO⁻ is further oxidized to non-toxic carbon dioxide (CO₂) and nitrogen (N₂).

Reaction Equations:

Procedure:

• Dissolve sodium hydroxide in water to adjust the solution’s pH to 11–12.
• Add cyanide waste to the alkaline solution and stir gently for complete dissolution.
• Introduce industrial bleaching powder while continuing gentle stirring to facilitate the reaction.
• The final products are non-toxic gases, ensuring safe disposal.

2. Biological Treatment

Microbial degradation of cyanide relies on four key biochemical processes: hydrolysis, oxidation, reduction, and substitution. Among these, hydrolysis and oxidation are the most prevalent mechanisms used in wastewater treatment systems.

Is Mining with Cyanide Chemicals Safe?

The safety of sodium cyanide and other mining chemicals hinges on proper handling protocols. Gold processing requires minimal amounts of sodium cyanide, and the substance is non-combustible. However, personnel handling cyanide bricks or solutions must always wear protective masks to avoid inhaling airborne dust or gases containing trace cyanide particles.

The safety of cyanide in mining ultimately depends on the integrity of the processing facility:

• Are materials clearly labeled and segregated by hazard class?
• Are staff trained in proper chemical handling and usage?
• Are rigorous protocols in place for quality control and safety checks at every operational stage?

When these standards are met, cyanide can be a safe and effective commercial chemical for mining.

DASENMINING specializes in supplying sodium cyanide to mining operations nationwide. We prioritize the safe handling of hazardous materials and deliver the highest-quality products to meet our clients’ needs.

Contact our on-staff scientists today to explore how NaCN can optimize your mining operations.