Wechat QR code
Wechat QR code
15311826613
Click to add WeChatThe international gold market is currently showing a fluctuating upward trend. As of 2025, New York gold futures prices are expected to stabilize in the range of $3300-3400 per ounce, while domestic Shanghai gold spot prices are expected to remain at 760-780 yuan per gram. Gold prices directly determine the economics of gold mining and beneficiation, and are a key indicator for defining the "mineable grade." Current gold prices present a crucial window for mining companies to expand capacity and obtain higher profits, representing a significant economic incentive and strategic opportunity. Currently, the utilization rate of whole-mud cyanidation carbon-in-pulp (CIP) technology for gold beneficiation can reach approximately 50%, making it the primary beneficiation technology for low-grade, fine-grained disseminated gold ores.
This article will focus on the whole-mud cyanidation carbon-in-pulp (CIP) adsorption gold extraction process, including what it is, applicable mineral types, and process flow.
The whole-sludge cyanide carbon-in-pulp process is a combination of "whole-sludge cyanidation" and "carbon-in-pulp adsorption," including two forms: CIP (carbon-in-pulp) and CIL (carbon-in-leaching):
Whole-sludge cyanidation: No pre-enrichment is required. The fully liberated ore slime is directly introduced into the cyanide leaching process, using the cyanide solution to dissolve the gold in the ore.
CIP (Cyanide-In-Place) leaching followed by adsorption: After cyanide leaching, the leached material enters an adsorption tank where it contacts activated carbon to recover gold.
CIL (Cyanide-In-Place) leaching and adsorption occur simultaneously: cyanide and activated carbon are added concurrently to a stirred tank, achieving dissolution and adsorption at the same time.
The main advantage of this gold extraction process is that it utilizes the large specific surface area and strong adsorption capacity of activated carbon to directly adsorb gold-cyanide complexes "in-situ" from the cyanide slurry. Unlike the zinc powder replacement method, it eliminates the need for complex solid-liquid separation and precious liquor clarification, simplifying the process and resulting in a lower gold loss rate.
Oxidized Ore: Gold in the ore is not encapsulated by sulfides and can directly contact and react with cyanide solution. It is an ideal raw material for the whole-sludge cyanide carbon-in-pulp process, with a recovery rate typically exceeding 92%.
Fine-Grained Disseminated Primary Ore: Gold particles are small and uniformly dispersed in gangue such as quartz and feldspar. Liberation is achieved through fine grinding of the raw ore to -200 mesh (90% or less), allowing for effective recovery of fine-grained gold via carbon-in-pulp processing.
Low-Grade Ore: When gold prices are high, gold ore with a grade of 0.5-1.0 g/t still has economic value. Valuable gold can be effectively recovered through a low-cost carbon-in-pulp process.
For the aforementioned difficult-to-process gold, the whole-sludge cyanidation carbon-in-pulp (CIP) process offers high recovery rates, greater adaptability, a simplified process, and controllable costs. Especially given the current global gold resource landscape characterized by "few rich ores, many poor ores, and associated and mixed minerals," it can maintain or even improve the overall profitability of mines.
The whole-sludge cyanidation carbon-in-pulp gold extraction process is relatively simple and safe. Starting from the raw ore, the process mainly includes pretreatment, concentration and slurry preparation, cyanidation leaching and carbon adsorption, gold-loaded carbon treatment, gold mud smelting, and tailings treatment.
Pretreatment mainly includes crushing and grinding/classification.
Raw Ore Crushing: Mined ore blocks of 0.5-1.5m are fed into crushers for coarse, medium, and fine crushing. Coarse crushing typically uses jaw crushers to reduce particle size to 200-300mm; medium crushing uses cone crushers to reduce particle size to 50-100mm; fine crushing uses impact crushers or high-pressure roller mills to reduce particle size to below -15mm.
Grinding and Classification: The finely crushed ore is mixed with water at a ratio of 1:1.5-1:2 and fed into a ball mill for grinding to fully liberate the particles. The mixture is then fed into a hydrocyclone for classification. The overflow is sent to subsequent processes, while the coarse underflow is returned to the ball mill for regrinding, forming a closed-loop cycle.
Thickening: The qualified slurry obtained from classification is fed into a thickener for gravity settling to increase the solids concentration to 40%-50%, thereby reducing the volume requirement of the subsequent leaching tank and lowering energy and reagent consumption. Flocculants (such as polyacrylamide) can be added during the thickening process to accelerate slurry settling and improve thickening efficiency.
Slurry Preparation: The concentrated slurry is fed into a conditioning tank. First, lime is added to adjust the pH to 10.5-11.5, making it alkaline. This inhibits the hydrolysis of cyanide to produce highly toxic HCN gas and creates an alkaline environment for the cyanidation reaction. Then, sodium cyanide solution is added to control the cyanide concentration (0.02%-0.05%), ensuring that the gold dissolves completely.
CIL (Chemical Injection Leaching) involves simultaneous leaching and adsorption in the same series of tanks; CIP (Chemical Injection Processing) is a two-stage design with independent leaching and independent adsorption.
Cyanide Leaching Reaction: Typically, CIL uses 6-12 aerated stirred tanks connected in series. The first 3-5 tanks are the main leaching section, and the latter 3-7 tanks are the leaching-adsorption synergistic section. When the slurry enters the first tank, cyanide and lime are added simultaneously to initiate the cyanide reaction in an alkaline environment. CIP's leaching system has 4-8 aerated stirred tanks separately, with subsequent adsorption tanks connected via a thickener. The slurry first enters the leaching tank to dissolve the gold, then passes through the thickener to remove excess water before entering the adsorption system.
Activated Carbon Adsorption: CIL (Continuous Intake) begins by adding 12-20 mesh coconut shell activated carbon from the 4th-6th stirred tanks. The slurry and activated carbon move counter-currently. Fresh activated carbon is added from the final tank and gradually moves towards the preceding tanks, adsorbing gold-cyanide complexes in the slurry. Saturated activated carbon is removed from the final tank. The CIP adsorption system consists of 3-6 stirred tanks connected in series. Activated carbon is added in a forward-flowing manner and discharged in a counter-current manner. Fresh activated carbon is added from the primary adsorption tank and flows with the slurry to the final tank, gradually becoming saturated during adsorption. The gold-loaded activated carbon is removed from the final tank, screened, and then sent to the desorption process.
Desorption: The gold-loaded carbon, saturated with adsorption, is sent to a desorption column. A high-temperature, high-pressure desorption method is used, with the carbon circulated and rinsed for 4-6 hours using a mixed hot solution of 0.5% NaOH and 1% NaCN. The gold-cyanide complex desorbs from the activated carbon surface and enters the solution, forming the precious solution.
Electrolytic deposition: The precious solution enters an electrolytic cell. A direct current is passed between the stainless steel cathode and the lead anode. The gold-cyanide complex gains electrons at the cathode and is reduced to metallic gold, depositing as gold mud. The lean solution after electrolysis is returned to the desorption process for recycling, reducing reagent consumption.
Activated Carbon Regeneration: The desorbed lean carbon is first washed with dilute hydrochloric acid to remove impurities such as calcium and magnesium adhering to the surface; then it enters an activation furnace and is heated for 2-4 hours in an inert gas atmosphere at 600-800℃ to burn off residual organic matter on the carbon surface, restoring the porous structure and adsorption activity; the regenerated activated carbon is returned to the adsorption process for recycling.
Gold Sludge Pretreatment: Gold sludge contains impurities such as silver, copper, and iron, and needs to be acid-washed with nitric acid and hydrochloric acid to remove most of the base metal impurities and improve the gold quality.
Smelting: The pretreated gold mud is added to a medium-frequency furnace along with a quantitative proportion of flux and smelted at a high temperature of 1200-1300℃. The flux reacts with impurities to form slag, and gold and silver form an alloy melt.
Ingot Casting and Refining: The alloy melt is poured into a mold and cooled to form Dol gold ingots. These ingots are then sent to a refinery for further electrolytic refining to remove impurities such as silver and copper, ultimately yielding standard gold ingots with a purity of 99.99% or higher.
Tailings Cyanide Removal: Commonly used methods include SO₂/air oxidation and hydrogen peroxide oxidation. The cyanide concentration in the tailings slurry must be reduced to below 0.5 mg/L to meet national emission standards.
Tailings Storage and Ecological Restoration: The decyanated tailings slurry is pumped to a tailings pond. After natural settling, the supernatant is returned to the grinding process for recycling. The tailings are layered and stacked in the tailings pond. Once full, the pond is covered with soil and planted with native vegetation to achieve ecological restoration, meeting the requirements of green mine construction.
The above is a complete analysis of the whole-sludge cyanidation carbon slurry adsorption gold extraction process. This method, with its advantages of high recovery rate, good economics, and simple process, has become the mainstream technology for extracting low-grade, fine-grained disseminated gold ores globally. In future development, this process will be upgraded towards intelligentization, low carbonization, and environmental protection, further improving resource utilization efficiency and environmental friendliness, providing technical support for the sustainable development of the gold industry.
For gold mining companies, choosing a suitable process solution and finding suitable partners are key to achieving stable profits and enhancing market competitiveness during gold price fluctuations.Xinhai Mining Equipment has over 30 years of experience in gold ore beneficiation and can provide customized technical solutions for beneficiation plants, encompassing beneficiation testing, plant design, equipment manufacturing, civil construction, installation, and commissioning.
CHAT
MESSAGE
Consult
Message
