Main Factors Impacting Gold Ore Heap Leaching and Their Synergistic Optimization

Heap leaching technology has become a core technology for the utilization of low-grade gold ore resources due to its simple process, low cost, and large processing capacity. Its leaching effect and cost control are affected by the synergy of multiple factors. Among them, comminution particle size is a core parameter, while ore properties, leaching process parameters, and monitoring technology also directly affect heap leaching efficiency. A systematic analysis is required to achieve process optimization.

Comminution particle size plays a decisive role in heap leaching effect. Moderate particle size can balance leaching rate and permeability: excessively coarse particles will prevent gold minerals inside the ore from fully contacting the leaching agent. For example, when the ore particle size exceeds 80 mm, the leaching rate decreases significantly; overly fine particles will reduce the porosity of the ore heap, causing partial flow of the spray solution. For instance, when the particle size decreases to -0.023 mm, the permeation rate drops sharply, which in turn affects leaching efficiency. At the same time, the uniformity of particle size distribution is crucial. When the proportion of the -0.074 mm particle size grade is uniform and reaches 60%, the leaching rate can reach 85%. However, when the distribution is uneven, the leaching rate is only 75%, and it will also cause the metal concentration in the leaching solution to fluctuate by 20%, increasing the difficulty of subsequent recovery.

Ore properties and leaching process parameters are important adjustment factors. Differences in ore characteristics such as composition and structure will change the heap leaching response. For example, fine disseminated gold ores require more precise particle size control because gold is encapsulated by sulfide minerals; ores containing associated elements such as copper and iron will change the dissolution amount of impurities with changes in particle size, affecting the treatment cost of the leaching solution. The dosage of the leaching agent is negatively correlated with particle size. When the particle size decreases from -0.074 mm to -0.045 mm, the dosage of sodium cyanide needs to increase from 800 g/t to 1000 g/t. It is necessary to balance cost and effect through reagent ratio optimization (such as adding leaching aids); parameters such as spray method and heap height also need to be adapted to the particle size to avoid local insufficient permeation or reagent waste.

Monitoring and control technology is the guarantee for process optimization. The online particle size monitoring system uses sensors and image recognition technology to collect particle size data in real time and transmit it to the central control system, helping operators adjust crushing parameters in a timely manner; the feedback control strategy can dynamically adjust the operating parameters of crushing equipment and ore conveying speed based on monitoring data. For example, Dong'an Gold Mine increased the ore processing capacity from 360 t/d to 720 t/d through the crushing and grinding control software, significantly improving the gold recovery rate. In addition, equipment upgrades (such as high-efficiency crushers) and the development of new leaching agents (such as low-consumption and high-efficiency reagents) can further reduce energy consumption and reagent costs. Among them, the cost of sodium cyanide accounts for 30%, and reagent consumption can be reduced by 10% after optimization.

In conclusion, gold ore heap leaching needs to take comminution particle size as the core, combine ore properties and process parameters, and rely on intelligent monitoring technology to achieve collaborative optimization. In the future, it is necessary to deepen the research on the coupling of particle size with parameters such as leaching agents and spray intensity, and promote the development of heap leaching technology towards low consumption, high efficiency, and intelligence, providing support for the efficient utilization of low-grade gold ore resources.