Low gold recovery rate? The problem is likely with the activated carbon.

In the cyanide leaching process (CIP/CIL/heap leaching), activated carbon serves as the core adsorption medium, directly determining the adsorption efficiency of gold and the final recovery rate. In actual production, when the recovery rate is consistently low or shows significant fluctuations, the problem is often not with the process itself, but rather with the performance and selection of the activated carbon.

I. Common Misconceptions Regarding Low Recovery Rates

Many enterprises tend to attribute low recovery rates to the properties of the ore or the leaching conditions, but overlook the crucial role of activated carbon. For instance, they solely rely on iodine value as the purchasing criterion, believing that "the higher the iodine value, the stronger the adsorption capacity." In reality, the iodine value can only reflect the microporous structure and provides limited indication of the actual adsorption performance of gold.

II. Key Properties of Carbon Affecting Gold Adsorption

1. Porosity compatibility: The gold cyanide complex molecules are large in size and rely on mesopores (2–50 nm) for adsorption. If the carbon material mainly consists of micropores, even with a high iodine value, it is difficult to achieve efficient adsorption.

2. Strength and wear resistance: In the CIP/CIL process, the carbon particles need to circulate in the tank for a long time. If the strength is insufficient, it is prone to powdering loss, reducing the effective carbon content and affecting the adsorption efficiency.

3. Ash content and impurity content: High ash content will occupy the effective adsorption sites and even introduce competitive adsorption, reducing the loading capacity of gold.

4. Surface chemical properties: The functional groups and polarity characteristics of the carbon surface will affect the affinity for gold complexes, thereby influencing the adsorption rate and capacity.

III. Optimization suggestions

1. Prioritize the use of coconut shell-based activated carbon: Its pore structure is more suitable for gold adsorption requirements, has high strength and good wear resistance, and is the mainstream choice in the industry.

2. Focus on comprehensive indicators rather than a single iodine value: Comprehensive evaluation of parameters such as pore size distribution, specific surface area, hardness, and ash content should be conducted.

3. Establish a dynamic monitoring mechanism: Regularly test the performance changes of the carbon and replenish or replace it in time to avoid "failed carbon" operating for a long time.

4. Customize carbon materials based on working conditions: Different properties of ores and process conditions have different requirements for activated carbon. Targeted selection should be made accordingly.

· Fujian Guangyuan Carbon Products Co.,Ltd.