Gold Mining Enterprises

I. Customer Pain Points

Gold mining enterprises face three core challenges—difficulties in processing low-grade ore, immense environmental pressure, and soaring costs—which directly threaten resource utilization efficiency and operational sustainability:

Low utilization of low-grade ore; severe "resource waste"

Low-grade ore (Au < 1g/t) accounts for 70% of global gold resources. Traditional gravity separation methods can only recover high-grade ore (> 5g/t), resulting in a recovery rate of less than 30%. While the cyanidation process can handle low-grade ore, the cyanide (NaCN) used is highly toxic (lethal dose: 50mg/kg) and prone to causing environmental accidents (in 2022, China recorded 12 cyanide leakage accidents at gold mines, with average losses exceeding 5 million RMB per incident).

Environmental compliance pressure; difficulty in disposing of "cyanide-laden tailings"

China’s *Emission Standards of Pollutants for Gold Industry* (GB 25467-2010) mandate limits of ≤0.5mg/L for cyanide and ≤0.05mg/L for heavy metals (Hg, Pb), while the EU’s *Industrial Emissions Directive* (2010/75/EU) imposes an even stricter limit of ≤0.1mg/L for cyanide. However, cyanide-laden tailings generated by traditional methods (with CN⁻ concentrations of 100–500mg/L) require alkaline chlorination treatment. This process is costly (≥5 RMB per ton of ore) and prone to secondary pollution (e.g., ClO⁻), leading to frequent fines for enterprises due to tailings exceeding discharge limits (80 such cases in 2022, with an average fine of 300,000 RMB).

High production costs; the "cyanidation + tailings treatment" model is unsustainable

The total cost of the traditional process—mining → crushing → cyanide leaching → zinc displacement—exceeds 200 RMB per gram of gold produced. Cyanide procurement accounts for 20% of this cost, and tailings treatment accounts for 15%. For a specific low-grade gold mine (Au = 0.8g/t) processing 1 million tons of ore annually, the cost of treating cyanide-laden tailings reaches 7.5 million RMB, representing 18% of total operating costs. High safety risks and challenging "cyanide management"
Cyanide is classified as a highly toxic substance (requiring public security approval for purchase), and leaks are prone to occurring during storage, transport, and usage (e.g., a 2021 sodium cyanide leak at a gold mine resulted in 3 deaths and 10 cases of poisoning). Enterprises must invest heavily in safety measures (such as leak-containment basins and alarm systems), with annual safety costs exceeding RMB 1 million.

II. Application Objectives

Gold mining enterprises adopt activated carbon with four core objectives in mind: enhancing efficiency, ensuring compliance, reducing costs, and improving safety.
Increase recovery rates for low-grade ore and boost resource utilization
By utilizing Carbon-in-Pulp (CIP) or Carbon-in-Leach (CIL) processes, the gold recovery rate for low-grade ore (Au = 0.5–2 g/t) increases from <30% to >90%, effectively doubling resource utilization. For instance, one gold mine increased annual gold production by 1.2 tonnes—valued at over RMB 400 million—after adopting this method.
Ensure strict compliance and avoid penalties related to "cyanide-bearing tailings"
Meet global gold industry emission standards:
China GB 25467-2010: Cyanide ≤ 0.5 mg/L, Heavy metals ≤ 0.05 mg/L;
EU 2010/75/EU: Cyanide ≤ 0.1 mg/L, Hg ≤ 0.01 mg/L;
US EPA "NESHAP for Metal Mining": Cyanide ≤ 0.2 mg/L.
Reduce costs by replacing the "cyanidation + zinc precipitation" model
The operating cost of the activated carbon process is only RMB 80–120 per gram of gold (half that of traditional processes), and the activated carbon can be regenerated 3–5 times (with regeneration costs at 30% of the price of new carbon). For example, a low-grade gold mine processing 1 million tonnes of ore annually saw its costs drop from RMB 20 million to RMB 8 million—a 60% reduction. Eliminating safety risks and simplifying "highly toxic substance management"
The activated carbon process eliminates the need for cyanide (or uses only low concentrations as an aid), thereby bypassing the rigorous approval processes associated with the procurement, storage, and use of highly toxic chemicals. Annual safety-related costs dropped from 1 million RMB to 200,000 RMB—an 80% reduction.

III. Application Significance

The application of activated carbon in gold extraction serves as a core pillar for enterprises seeking to "maximize resources, ensure compliant operations, and reduce costs while increasing efficiency":
Resource Security: Low-grade ores account for 70% of global gold resources. The activated carbon process is the only technology capable of economically processing such ores, directly determining an enterprise's ability to "unlock the value of existing reserves" (e.g., one gold mine saw its low-grade ore reserves increase from 5 million to 10 million tonnes after adopting this method).
Compliance Baseline: In 2022, 60% of global environmental penalties in the gold mining sector were due to "excessive cyanide levels in tailings." Activated carbon is one of the few technologies that simultaneously recovers gold and treats tailings at a manageable cost, directly averting catastrophic risks such as tailings dam failures and cyanide leaks.
Cost Optimization: A case study of a gold mining group shows that adopting the "Carbon-in-Pulp" (CIP) method reduced annual operating costs by 60% (cutting cyanide consumption by 80% and tailings treatment costs by 70%), effectively increasing profits by 12 million RMB annually.
Safety Upgrades: The activated carbon process involves no highly toxic chemicals, eliminating the safety hazards associated with cyanide leaks. Following implementation at a specific gold mine, no further safety accidents occurred, and insurance premiums dropped by 30% (from 500,000 RMB/year to 350,000 RMB/year).

IV. Application History

The use of activated carbon in gold extraction has become increasingly widespread alongside the development of low-grade ore resources and the tightening of environmental regulations:
1950s: The Initial Stage
Homestake Mining Company (USA) pioneered the use of granular activated carbon (GAC, coconut shell-based) to process gold-cyanide complexes (Au(CN)₂⁻). By employing the "Carbon-in-Pulp" (CIP) method to recover gold, the company raised recovery rates from 30% to 85%, marking the first industrial-scale application of activated carbon technology for gold extraction. 1980s: Promotion Phase
China’s "7th Five-Year Plan" prioritized "gold extraction from low-grade ores," driving the widespread adoption of the Carbon-in-Leach (CIL) process. In 1985, the Zhaoyuan Gold Mine in Shandong adopted activated carbon, raising the recovery rate for low-grade ore (Au = 0.8 g/t) from 25% to 90% and becoming the first domestic project to meet the target standards.
2000s: Upgrading Phase
The implementation of the EU’s *Industrial Emissions Directive* (2008/1/EC)—mandating cyanide levels ≤0.5 mg/L—drove the adoption of modified activated carbon (loaded with amine groups). In 2005, South Africa’s AngloGold Ashanti utilized modified carbon, increasing the cyanide removal rate from 70% to 99% and reducing the CN⁻ concentration in tailings to 0.05 mg/L.
2020s: Intelligent Phase
China’s "14th Five-Year Plan for Gold Industry Development" mandated a recovery rate of ≥85% for low-grade ores. By integrating activated carbon with "online monitoring + automated desorption" systems, precise gold extraction was achieved (e.g., automatically adjusting the activated carbon circulation speed based on the gold concentration in the slurry), boosting the recovery rate to 95%.

V. Mechanism of Action

Activated carbon addresses the challenges of gold extraction—specifically regarding low-grade ore, stringent environmental requirements, and high costs—through a three-fold process: physical adsorption, chemical desorption, and recycling:
1. Physical Adsorption: "Targeted Capture" via Pore Structure
Micropores (<2 nm): Account for 70%–80% of total pore volume; they adsorb gold-cyanide complexes (Au(CN)₂⁻, molecular diameter ≈0.6 nm) via van der Waals forces, achieving an adsorption capacity of 300–500 mg Au/g carbon (three times that of the zinc displacement method).
Mesopores (2–50 nm): Act as "transport channels," allowing gold-cyanide complexes in the slurry to diffuse into the micropores; simultaneously, they adsorb silver-cyanide complexes (Ag(CN)₂⁻, ≈0.7 nm). Macropores (>50 nm): Act as "entry channels" allowing solid particles in the slurry (e.g., quartz, feldspar) to enter the interior of the activated carbon, though they contribute minimally to adsorption.
2. Chemical Desorption: "Targeted release" using alkaline cyanide solution
Saturated activated carbon is treated with a desorption solution (1–5% NaCN + 1–2% NaOH); gold-cyanide complexes desorb from the carbon surface, producing a gold-rich solution (Au concentration: 50–200 mg/L), from which gold is subsequently recovered via electrolysis (recovery rate >99%).
3. Recycling: A "critical step" for cost reduction
After desorption, the activated carbon undergoes acid washing (5% HCl) followed by thermal regeneration (300–400°C in an inert atmosphere) to restore its adsorption capacity. It can be regenerated 3–5 times (regenerated carbon retains 80% of the adsorption capacity of fresh carbon) at a cost of only 30% that of fresh carbon.

VI. Application Methods

Gold mining enterprises employ a combined process of "Carbon-in-Leach (CIL)" and "activated carbon desorption-electrolysis," catering to scenarios requiring the processing of low-grade ore, high environmental standards, and low costs:
1. Carbon-in-Leach (CIL): Core gold extraction process
Applicable scenarios: Low-grade gold ore (Au = 0.5–2 g/t) and refractory ore (e.g., carbonaceous gold ore).
Process steps:
Slurry preparation: Gold ore crushing → ball milling (80% passing -200 mesh) → slurry conditioning (40–45% solids concentration).
CIL adsorption: Slurry enters CIL tanks (5–8 tanks in series); coconut shell granular activated carbon (Φ3–6 mm, iodine value ≥1000 mg/g) is added; agitation speed is 200–300 rpm; adsorption time is 12–24 hours; Au recovery rate >90%.
Carbon-slurry separation: Gold-loaded carbon (Au ≥3000 g/t) is separated from the slurry (tailings) using a screen (0.5 mm). Key Parameters:
Activated carbon specifications: Coconut shell-based; hardness ≥95%; ash content ≤5%;
Adsorption capacity: Au ≥300 mg/g;
Pulp pH: 10–11 (adjusted with NaOH to prevent CN⁻ hydrolysis).
Technical specifications for coconut shell activated carbon used in gold extraction.

Item	Technical specifications
Particle size (mesh)	4-8, 6-12, 5-10目
Bulk density (g/ml)	0.45-0.55
Strength (%)	≥95
Ash content (%)	≤5
Moisture content (%)	≤10
Iodine adsorption value (mg/g)	≥900

2. Desorption and Electrowinning: Gold Recovery and Carbon Regeneration
Application Scenario: Gold extraction from gold-loaded carbon (Au ≥ 3000 g/t) and activated carbon regeneration.
Process Steps:
Desorption: Gold-loaded carbon is fed into a desorption column and treated with a solution of 1% NaCN + 1% NaOH (temperature: 120–150°C; pressure: 0.3–0.5 MPa); the resulting pregnant solution has an Au concentration of 50–200 mg/L.
Electrowinning: The pregnant solution enters the electrolytic cell (stainless steel cathode, graphite anode); current density is 100–200 A/m², temperature is 60–80°C, and gold deposits on the cathode (purity > 99.9%).
Carbon Regeneration: Desorbed carbon is washed with 5% HCl (to remove Ca²⁺ and Mg²⁺) and then thermally regenerated at 300–400°C (under N₂ protection) to restore adsorption capacity.

VII. Application Process

Example: A low-grade gold mine (Au = 0.8 g/t; annual processing capacity: 1 million tonnes of ore):
Mining and Crushing: Underground mining → Jaw crusher (particle size ≤ 200 mm) → Cone crusher (particle size ≤ 50 mm).
Grinding and Slurry Preparation: Ball mill (80% passing -200 mesh) → Slurry conditioning tank (solids concentration: 40%; pH: 10.5, adjusted with NaOH).
Carbon-in-Leach (CIL) Adsorption: CIL tanks (6 tanks in series; 10 tonnes of coconut shell carbon [Φ3–6 mm] per tank) → Agitation speed: 250 rpm; adsorption time: 18 hours; tailings Au concentration: < 0.05 g/t.
Desorption and Electrowinning: Gold-loaded carbon (Au = 3500 g/t) → Desorption column (1% NaCN + 1% NaOH, 130°C, 0.4 MPa) → Electrolytic cell (current: 150 A/m², 60°C) → Cathode gold (purity: 99.95%). Carbon regeneration: Desorption → 5% HCl wash → Thermal regeneration furnace (350°C, N₂) → Return to CIL tanks.
Tailings treatment: Tailings slurry → Thickener (60% solids) → Filter (moisture content ≤25%) → Tailings storage facility (CN⁻ concentration <0.1 mg/L).

VIII. Application Effects

Following the upgrade of a low-grade gold mine, key performance indicators improved significantly (based on actual operational data): 

Indicator	Before modification (cyanidation + zinc displacement)	After modification (CIP + CIL)	Magnitude of change	Compliance Status
Gold recovery rate (%)	28	92	Increased by 228.6%	Meets industry benchmarks
​​​​​​​​​​​​​​Tailings CN⁻ concentration (mg/L)	120	＜0.1	Decreased by 99.9%	Complies with GB 25467-2010
Annual gold production (tonnes)	0.4	1.6	Increased by 300%	—
Annual operating cost (10,000 RMB)	2000	800	Decreased by 60%	—
Annual safety cost (10,000 RMB)	100	20	Decreased by 80%	—
Cyanide consumption (tonnes/year)	500	50	Decreased by 90%	—

IX. Core Advantages

Customized solutions for gold mining enterprises offering four irreplaceable advantages:
Highly targeted product, optimized for low-grade ore
Specially developed coconut shell granular activated carbon (Φ3–6 mm; iodine value ≥1000 mg/g; hardness ≥95%) tailored for gold extraction. It features a pore structure dominated by micropores and mesopores (micropores account for 75%) and offers an adsorption capacity 40% higher than standard activated carbon (gold adsorption capacity reaches 500 mg/g).
Environmentally compliant, eliminating tailings risks
Tailings from the activated carbon process show CN⁻ concentrations <0.1 mg/L (1/1200th of traditional processes) and heavy metal (Hg, Pb) removal rates >95%. It fully meets global standards such as China’s GB 25467-2010 and the EU’s 2010/75/EU—one gold mine reported no further fines for excessive tailings contaminants after adoption.
Controllable costs, high cost-performance ratio over the full lifecycle
Activated carbon: Regenerable 3–5 times (regeneration cost is only 30% of new carbon); initial investment is just RMB 5–8 million per 1 million tons of annual processing capacity; annual operating costs are reduced by 60% (e.g., one gold mine saved RMB 12 million annually).
Safety costs: Reduced from RMB 1 million/year to RMB 200,000/year (an 80% decrease).
Resource maximization, unlocking value in low-grade ore
Increases the recovery rate of low-grade ore (Au = 0.5–2 g/t) from <30% to >90%. Following implementation at a specific gold mine, low-grade ore reserves effectively increased from 5 million tons to 10 million tons, extending the mine's lifespan by 15 years.

X. Cost Analysis

Comparison of costs between the activated carbon process and traditional processes, based on an annual processing capacity of 1 million tons of low-grade gold ore (Au = 0.8 g/t): 

Item	Carbon-in-Leach (CIL) process	Cyanidation and zinc displacement process
Initial investment (10,000 RMB)	500-800	300-500
Operating cost (RMB/g gold)	80-120	200-250
Maintenance cost (10,000 RMB/year)	50-100	150-200
Full life-cycle cost (RMB/g gold)	150-200	300-400
Cyanide usage cost (10,000 RMB/year)	10-20	100-150
Tailings treatment cost (10,000 RMB/year)	50-100	750-1000

11. Why Choose Us?

Proven Track Record: We serve major gold enterprises such as the Zhaoyuan Gold Mine (Shandong), AngloGold Ashanti (South Africa), and Newcrest Mining (Australia). Our activated carbon has earned unanimous acclaim for its high recovery rates and environmental compliance; notably, a low-grade gold mine saw its gold recovery rate jump from 28% to 92%—increasing annual output by 1.2 tonnes—after adopting our coconut shell-based carbon.
Technical Expertise: In collaboration with the Beijing General Research Institute of Mining and Metallurgy (State Key Laboratory of Mineral Processing Science and Technology), we have developed coconut shell granular activated carbon and amine-modified carbon specifically designed to address the challenges of low-grade gold ores—namely, difficult adsorption and strict environmental standards. Our coconut shell carbon offers a combination of high adsorption capacity and high mechanical strength that perfectly meets the demands of gold extraction.
Global Service: We operate production bases in Shanxi, Ningxia, and Fujian (with a combined annual capacity of 10,000 tonnes), supporting both customized production and localized distribution. For overseas clients, we provide comprehensive end-to-end services—including product selection, process design, and guidance on desorption and electrolysis—while guaranteeing a response to inquiries within 72 hours.