Reduce the chemical loss of sodium cyanide solution - Protect the base

Sodium cyanide solutions play a pivotal role in the extraction of precious metals, especially in the gold mining industry. Given their widespread use, maintaining the stability of these solutions becomes crucial. Sodium cyanide’s chemical reactivity, however, makes it prone to significant losses without proper safeguards.

The Multifaceted Role of Protective Alkali

Preserving Solution Integrity

Adding an appropriate quantity of alkali—termed protective alkali—addresses the instability issue. It serves as a stabilizing agent, reducing chemical losses of Sodium cyanide.

Neutralizing Reactive Compounds

The protective alkali also neutralizes carbon dioxide in the solution. Additionally, it counteracts the acids produced by the oxidation of sulfide minerals, maintaining a balanced chemical environment.

The Pitfalls of Excessive Alkalinity

Despite its importance, an overly high level of alkalinity can impede the extraction process. For one, it slows down the rate at which gold dissolves in the cyanide solution. Additionally, it leads to increased consumption of zinc during the displacement step, which is essential for recovering gold.

Lime: The Preferred Protective Alkali

Cost - Effective Alkalinity Control

Lime is a popular choice for maintaining the required alkalinity due to its cost - effectiveness. It effectively performs the functions of protective alkali.

Flocculation Benefits

Beyond alkalinity control, lime aids in the flocculation of fine - grained minerals and slimes in the pulp. This improves the separation and processing of minerals, enhancing overall operational efficiency.

Optimal Parameter Control in Industrial Settings

pH and Calcium Oxide Concentration

In industrial production, maintaining the solution’s pH between 11 and 12 is highly recommended. This is achieved by carefully controlling the concentration of free calcium oxide (CaO) to 1 - 3 parts per ten thousand. Precise regulation of these parameters is key to ensuring the smooth operation of the cyanidation process. It maximizes the recovery of precious metals while minimizing both chemical losses and production costs.