Introduction to the process flow of gold ore desorption electrolysis

Gold ore desorption electrolysis technology is an important part of modern gold ore dressing process, mainly used for efficient recovery of gold from leachate. This technology is usually used in combination with cyanidation, especially after processes such as carbon-in-pulp (CIP) or carbon-in-leach (CIL).

The process flow of desorption electrolysis mainly includes gold-loaded carbon pretreatment, analytical operation, analytical solution collection, electrolytic deposition and product processing.

1. Gold-loaded carbon pretreatment

Cleaning: Place the gold-loaded carbon in a special cleaning equipment, inject sufficient clean water, turn on the stirring device, and control the stirring speed at 100-150 rpm to fully mix the gold-loaded carbon with water. Through stirring, mechanical force can remove the ore mud, fine impurities, etc. attached to the surface of the gold-loaded carbon. After continuous stirring for 1-2 hours, solid-liquid separation is carried out. The washed gold-loaded carbon can be separated from the sewage by filtration or sedimentation. Repeat the washing 2-3 times until the washing water is clear and transparent to ensure that the impurities on the surface of the gold-loaded carbon are completely removed.

Drying: The washed gold-loaded carbon contains a lot of water and needs to be dried. Transfer the gold-loaded carbon to a drying device, such as a hot air drying oven. Set the drying temperature to 80-100°C and use hot air circulation to heat the gold-loaded carbon evenly. The drying time depends on the amount of gold-loaded carbon and the initial water content, generally 3-5 hours. During this period, the gold-loaded carbon is turned over regularly to prevent local overheating or uneven drying. When the water content of the gold-loaded carbon drops below 5%, the drying is completed, creating good conditions for the subsequent analytical reaction.

2. Analysis operation

Analysis tower preparation: Add an appropriate amount of heat exchange medium to the analytical tower, and preheat the analytical tower to 120-150°C through an external heating device.

Addition of gold-loaded carbon and analytical agent: Slowly add the pretreated gold-loaded carbon to the analytical tower, and control the filling amount to 60%-80% of the volume of the analytical tower. Then, add a specific analytical agent according to the mass ratio of gold-loaded carbon to analytical agent 1: (2-3). Such as a mixed solution of sodium hydroxide and sodium carbonate, in which the concentration of sodium hydroxide is generally 0.5-1mol/L; the concentration of sodium carbonate is 0.2-0.5mol/L.

Reaction condition control: After the addition is completed, turn on the stirring device of the analytical tower, and set the stirring speed to 80-120 rpm to make the gold-loaded carbon fully contact with the analytical agent. Maintain the temperature in the analytical tower at 120-150℃, and adjust the temperature through the circulation of the heat exchange medium and the heating device. The analytical reaction time is 6-8 hours, during which the solution composition in the analytical tower and the gold content of the gold-loaded carbon are regularly detected to ensure that the reaction is fully carried out.

3. Analysis liquid collection

Filtration separation: After the analytical reaction is completed, the solid-liquid mixture in the analytical tower is transported to the filtering equipment, such as a plate and frame filter press or a vacuum filter, through a pipeline. By filtration, the gold-loaded carbon is separated from the analytical solution, and the gold-loaded carbon can be subsequently regenerated or recycled.

Storage tank storage: The filtered analytical solution flows into the liquid storage tank, which needs to have good sealing and corrosion resistance. A level meter and a pH meter are set in the liquid storage tank to monitor the liquid level and pH of the analytical solution in real time to ensure that the analytical solution is stable during storage, avoid external factors affecting the composition of the analytical solution, and provide qualified raw materials for subsequent electrolysis.

4. Electrolytic deposition

Preparation of the electrolytic cell: The electrolytic cell needs to be thoroughly cleaned before use, and the electrode connection should be checked to see if it is firm and whether the distance between the cathode and cathode meets the requirements. Generally, the distance between the cathode and cathode is controlled at 5-10 cm. Add an appropriate amount of supporting electrolyte solution, such as potassium sulfate solution, to the electrolytic cell with a concentration of 0.1-0.3 mol/L to improve the conductivity of the solution.

Injection of analytical solution: Use a corrosion-resistant pump to slowly pump the analytical solution in the liquid storage tank into the electrolytic cell, and the injection amount is 80%-90% of the volume of the electrolytic cell. At the same time, turn on the stirring device of the electrolytic cell, and the stirring speed is 50-80 rpm to evenly distribute the analytical solution.

Electrolysis parameter control: Connect the DC power supply, set the electrolysis current density to 100-200A/㎡, and the voltage to 2-3V. During the electrolysis process, pay close attention to the changes in current and voltage, and check the electrolyte composition every 1-2 hours. As the electrolysis proceeds, the gold ions obtain electrons on the cathode and gradually deposit as metallic gold. The electrolysis time is generally 4-6 hours, until the gold ion concentration in the electrolyte drops to the specified low value.

5. Product processing

Gold nugget stripping: After the electrolysis is completed, turn off the power and remove the cathode plate. Soak the cathode plate in a specific stripping solution, such as a dilute nitric acid solution, for 10-20 minutes to separate the metallic gold from the cathode plate. Then, the gold nuggets deposited on the cathode plate are stripped off by mechanical scraping or rinsing.

Smelting: Transfer the stripped gold nuggets to a smelting furnace and add an appropriate amount of flux, such as borax and sodium carbonate. The mass ratio of flux to gold nuggets is (1-2):10. Smelt at a high temperature of 1200-1400℃ for 1-2 hours to fully melt the gold nuggets, and the impurities and flux form slag floating on the surface. The slag is removed by skimming.

Refining: Electrolytic refining or chemical refining is used to further purify gold. During electrolytic refining, the smelted crude gold is used as the anode, the pure gold flakes are used as the cathode, and the electrolyte is a solution containing gold ions. Under the action of the DC electric field, the anode crude gold dissolves, the gold ions are deposited on the cathode, and the impurities remain in the anode mud or electrolyte. After refining, gold ingots with a purity of more than 99.9% can be obtained.

The above is a detailed introduction to the gold ore desorption electrolysis process. As an important part of gold ore beneficiation, this process realizes the recovery and purification of gold through effective analysis and electrolysis processes. Although this technology faces certain energy consumption and reagent consumption problems, its advantages of high recovery rate and high purity have made it widely used in modern gold ore beneficiation. Future research and development directions will pay more attention to technological innovation and the implementation of environmental protection measures to promote the sustainable development of the gold ore beneficiation industry.