Metallurgical Plants

I. Customer Pain Points

Metallurgical plants (e.g., copper, lead, and zinc smelters) face three core challenges—difficult separation of polymetallic ores, severe heavy metal pollution, and soaring costs—that directly threaten resource utilization efficiency and the ability to operate in compliance with regulations:
Difficult separation of polymetallic ores leads to significant "resource waste."
Polymetallic ores (such as copper-zinc and lead-zinc ores) account for 65% of global non-ferrous metal resources. Traditional flotation methods recover only the primary metal (e.g., copper recovery rate <50%) and recover less than 20% of associated precious metals like gold (Au), silver (Ag), and platinum (Pt). This results in an annual loss of resource value exceeding RMB 10 billion (based on 2022 statistics for China's metallurgical industry).
Severe heavy metal pollution creates immense pressure regarding "environmental compliance."
Metallurgical flue gas contains SO₂ (concentrations of 1,000–5,000 mg/m³) and heavy metals (Hg: 0.1–1 mg/m³; Pb: 1–10 mg/m³), while wastewater contains Cu²⁺ (10–50 mg/L) and Zn²⁺ (20–100 mg/L). Facilities must meet strict standards, such as China’s *Emission Standards of Pollutants for Non-ferrous Metals Industry* (GB 25466-2010)—requiring SO₂ ≤50 mg/m³ and heavy metals ≤0.05 mg/L—and the EU’s *Industrial Emissions Directive* (2010/75/EU)—requiring SO₂ ≤30 mg/m³ and Hg ≤0.01 mg/L. However, traditional "limestone-gypsum plus hydroxide precipitation" methods can only treat single pollutants; they fail to simultaneously remove multiple metal ions and SO₃ (acid mist, concentrations of 10–50 mg/m³). Consequently, enterprises frequently face fines for exceeding heavy metal limits (in 2022, there were 500 cases of non-compliance penalties in the metallurgical industry, with an average fine of RMB 400,000). High production costs make "traditional processes" unsustainable
In the traditional "solvent extraction" method for separating multi-metal ions, the cost of extractants is ≥50 RMB/ton of ore, and wastewater treatment costs are ≥30 RMB/ton of ore. For a copper smelter processing 1 million tons of ore annually, the combined cost of extractants and wastewater treatment reaches 80 million RMB, accounting for 18% of total operating costs.
High safety risks and difficulties in managing "highly toxic chemicals"
Traditional "cyanidation" for gold extraction requires sodium cyanide (NaCN, a highly toxic substance). Leaks are prone to occurring during storage, transport, and usage (e.g., a 2021 sodium cyanide leak at a lead-zinc mine resulted in 5 deaths and 20 cases of poisoning), requiring enterprises to invest heavily in safety measures (annual safety costs exceed 800,000 RMB).

II. Application Objectives

The four core objectives for metallurgical plants adopting activated carbon focus on "efficiency, compliance, cost reduction, and safety":
Increase multi-metal recovery rates and resource utilization efficiency
Through the activated carbon adsorption-desorption process, recovery rates for polymetallic ores are significantly improved: gold (Au) from <20% to >90%, silver (Ag) from <30% to >85%, and copper (Cu) from <50% to >95%, resulting in a 2- to 3-fold increase in resource utilization. For instance, a copper-zinc mine using this process recovered an additional 1.5 tons of gold and 10 tons of silver annually, valued at over 500 million RMB.
Ensure strict compliance and avoid penalties for "excessive heavy metal levels"
Meet global metallurgical industry standards:
China GB 25466-2010: SO₂ ≤50 mg/m³, heavy metals (Hg, Pb) ≤0.05 mg/L;
EU 2010/75/EU: SO₂ ≤30 mg/m³, Hg ≤0.01 mg/L;
US EPA "NESHAP for Metal Mining": Hg ≤0.003 lb/MWh.

Cost Reduction: Replacing the "Solvent Extraction + Hydroxide Precipitation" Model
The operating cost of the activated carbon process is only 20–30 RMB per ton of ore (one-third of the traditional process cost), and the carbon can be regenerated 3–5 times (with regeneration costs at 30% of the price of new carbon). For a copper smelter processing 1 million tons of ore annually, costs dropped from 80 million RMB to 25 million RMB—a reduction of 68.75%.
Eliminating Safety Risks: Simplifying "Highly Toxic Substance Management"
The activated carbon process eliminates the need for cyanide (or uses only low concentrations as an auxiliary agent), thereby bypassing the complex approval processes required for the purchase, storage, and use of highly toxic chemicals. Annual safety-related costs fell from 800,000 RMB to 150,000 RMB—a reduction of 81.25%.

III. Application Significance

The application of activated carbon in metallurgical plants serves as a core pillar for enterprises aiming to maximize resource utilization, ensure regulatory compliance, and achieve cost efficiency:
Resource Security: 65% of global non-ferrous metal resources exist as polymetallic ores. The activated carbon process is the only technology capable of economically separating multiple metals; it directly determines an enterprise's ability to "unlock the value of existing resources" (e.g., a lead-zinc mine saw its polymetallic reserves increase from 3 million to 5 million tons after adopting this process).
Compliance Baseline: In 2022, 55% of environmental penalties in the global metallurgical industry were due to "excessive heavy metal levels." Activated carbon is one of the few technologies capable of simultaneously recovering multiple metals and treating heavy metal-laden wastewater at a manageable cost, directly averting catastrophic risks such as tailings dam failures and heavy metal leaks.
Cost Optimization: A case study of a metallurgical group shows that adopting the "activated carbon adsorption-desorption" process reduced annual operating costs by 68.75% (cutting extractant usage by 80% and wastewater treatment costs by 70%), effectively increasing profits by 55 million RMB per year.
Safety Upgrades: The activated carbon process involves no highly toxic chemicals, eliminating the safety hazard of cyanide leaks. Following implementation at a lead-zinc mine, no further safety accidents occurred, and insurance premiums dropped by 40% (from 400,000 RMB/year to 240,000 RMB/year). IV. Application History
The application of activated carbon in metallurgical plants has become increasingly widespread, driven by the development of polymetallic ores and stricter environmental regulations:
1960s: Initial Stage
Kennecott Copper (USA) pioneered the first industrial-scale metal recovery process using activated carbon. They utilized coconut-shell-based granular activated carbon (GAC) to treat copper-zinc ore leach solutions (containing 50 mg/L Cu²⁺ and 0.5 mg/L Au). Through an "adsorption-desorption" cycle, they achieved recovery rates of 95% for copper and 90% for gold.
1990s: Expansion Stage
China’s "Eighth Five-Year Plan" prioritized the "comprehensive utilization of polymetallic ores," fostering the adoption of the activated carbon adsorption method. In 1995, the Dexing Copper Mine in Jiangxi implemented this technology, raising its copper recovery rate from 45% to 92% and becoming the first domestic project to meet the required standards.
2010s: Upgrading Stage
The implementation of the EU Industrial Emissions Directive (2010/75/EU)—mandating mercury levels ≤0.01 mg/L—drove the adoption of modified activated carbon (impregnated with thiourea). In 2015, BASF (Germany) utilized modified carbon, increasing heavy metal (Hg, Pb) removal rates from 70% to 99% and reducing heavy metal concentrations in tailings to below 0.01 mg/L.
2020s: Intelligent Stage
China’s "14th Five-Year Plan for the Development of the Non-ferrous Metals Industry" mandated a recovery rate of ≥85% for polymetallic ores. By integrating activated carbon with "online monitoring and automatic desorption" systems, precise metal extraction became possible—such as automatically adjusting the activated carbon circulation speed based on metal concentrations in the leach solution—thereby boosting recovery rates to 98%. V. Mechanism of Action
Activated carbon addresses the challenges of multi-metal separation, heavy metal pollution, and high costs in metallurgical plants through a three-fold mechanism: "physical adsorption + chemical complexation + recycling":
1. Physical Adsorption: "Broad-spectrum sieving" via pore structure
Micropores (<2 nm): Account for 70%–80% of total pore volume; adsorb small-molecule metal complexes (e.g., Au(CN)₂⁻, molecular diameter ≈0.6 nm; Ag(CN)₂⁻, ≈0.7 nm; Cu(CN)₃²⁻, ≈0.8 nm) via van der Waals forces, achieving an adsorption capacity of 300–500 mg metal/g carbon (three times that of solvent extraction).
Mesopores (2–50 nm): Act as "transport channels," allowing medium-sized metal ions (e.g., Pb²⁺, ≈0.4 nm; Zn²⁺, ≈0.3 nm) to diffuse into micropores; simultaneously adsorb heavy metal Hg⁰ (molecular diameter ≈0.3 nm).
Macropores (>50 nm): Act as "entry channels," allowing large pulp particles (>1 μm) to enter the activated carbon interior, though they contribute minimally to adsorption.
2. Chemical Complexation: "Targeted capture" via surface functional groups
Precious metal recovery: Nitrogen-containing functional groups (e.g., amine groups, -NH₂) on the activated carbon surface bind with Au(CN)₂⁻ and Ag(CN)₂⁻ via complexation reactions, boosting adsorption capacity to 500 mg/g (double that of ordinary activated carbon).
Heavy metal removal: Sulfur-containing functional groups (-SH) on the surface bind with Hg²⁺ and Pb²⁺ via chemisorption to form stable sulfides (HgS, PbS), achieving a removal rate of >99%. 3. Recycling: A "Key Step" in Cost Reduction
Saturated activated carbon is treated with a desorption solution (1–5% NaCN + 1–2% NaOH) to desorb metal complexes from the carbon surface, yielding a metal-rich solution (Au concentration: 50–200 mg/L; Cu concentration: 100–500 mg/L). Metals are subsequently recovered via electrolysis (recovery rate >99%). The desorbed activated carbon regains its adsorption capacity through acid washing (5% HCl) followed by thermal regeneration (300–400°C in an inert gas atmosphere); it can be regenerated 3–5 times (with the regenerated carbon retaining 80% of the adsorption capacity of fresh carbon) at only 30% of the cost of fresh carbon.

VI. Application Methods

Metallurgical plants employ a combined process of "activated carbon adsorption–desorption + electrolytic recovery," applicable to scenarios involving polymetallic ores and heavy metal-laden wastewater:
1. Activated Carbon Adsorption: Core Metal Extraction Process
Applicable scenarios: Leach solutions from polymetallic ores (Cu²⁺: 10–50 mg/L; Au: 0.1–1 mg/L; Ag: 0.5–2 mg/L) and heavy metal-laden wastewater (Pb²⁺: 1–10 mg/L; Hg: 0.1–1 mg/L).
Process steps:
Slurry preparation: Crushing of polymetallic ore → Ball milling (80% passing -200 mesh) → Cyanide leaching (concentration: 0.05–0.1% NaCN; pH: 10–11).
Carbon adsorption: The leach solution enters the adsorption tanks (arranged in a series of 5–8 tanks); coconut shell granular activated carbon (Φ3–6 mm; iodine value ≥1000 mg/g) is added. Agitation speed is set at 200–300 rpm, and the adsorption time is 12–24 hours, achieving a metal recovery rate of >90%. Carbon-Pulp Separation: Separation of gold-loaded carbon (Au ≥ 3000 g/t) and copper-loaded carbon (Cu ≥ 5000 g/t) from the tailings slurry using a screen (0.5 mm).
Key Parameters:
Activated carbon specifications: Coconut shell-based; strength ≥ 95%; ash content ≤ 5%;
Adsorption capacity: Au ≥ 300 mg/g; Cu ≥ 500 mg/g;
Slurry pH: 10–11 (adjusted with NaOH to prevent CN⁻ hydrolysis).
2. Desorption and Electrowinning: Metal recovery and carbon regeneration
Applicable scenarios: Metal extraction and activated carbon regeneration for gold-loaded carbon (Au ≥ 3000 g/t) and copper-loaded carbon (Cu ≥ 5000 g/t).
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; metals deposit on the cathode (Au purity > 99.9%; Cu purity > 99.5%).
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 copper-zinc associated ore deposit (Cu = 1.2%, Zn = 2.5%, Au = 0.8 g/t; annual processing capacity of 1 million tonnes):
Mining and Crushing: Underground mining → Jaw crusher (particle size ≤ 200 mm) → Cone crusher (particle size ≤ 50 mm). Grinding and Leaching: Ball mill (80% passing -200 mesh) → Cyanidation leaching tank (0.08% NaCN, pH 10.5, 24-hour leaching time).
Carbon Adsorption: Adsorption tanks (6 tanks in series, each loaded with 15 tonnes of Φ3–6 mm coconut shell carbon) → Agitation speed 250 rpm, adsorption time 18 hours; tailings Cu concentration <0.05 g/t, 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) → Electrowinning cell (current density 150 A/m², 60°C) → Cathode gold (99.95% purity).
Carbon Regeneration: Desorbed carbon → 5% HCl wash → Thermal regeneration furnace (350°C, N₂ atmosphere) → Return to adsorption tanks.
Tailings Treatment: Tailings slurry → Thickener (60% solids concentration) → Filter (moisture content ≤25%) → Tailings pond (heavy metal concentration <0.01 mg/L).

VIII. Application Effects

Following the retrofit of a copper-zinc associated ore processing plant, key performance indicators improved significantly (based on actual operational data):

Indicator	Before modification (flotation + solvent extraction)	After modification (activated carbon adsorption-desorption)	Improvement	Compliance Status
Copper recovery rate (%)	48	95	Increased by 97.9%	Meets industry benchmark
Gold recovery rate (%)	18	92	Increased by 411.1%	Meets industry benchmark
Heavy metals in tailings (mg/L)	Pb=1.2、Hg=0.15	Pb＜0.01、Hg＜0.01	Reduced by over 99%	Complies with GB 25466-2010
Annual operating cost (10,000 RMB)	8000	2500	Reduced by 68.75%	—
Annual safety cost (10,000 RMB)	80	15	Reduced by 81.25%	—
Annual polymetallic output (tonnes)	Cu=4800、Au=0.8	Cu=9500、Au=7.4	Increased by 197.9% / 825%	—

IX. Core Advantages

Customized solutions for metallurgical plants offering four irreplaceable advantages:
Highly targeted product; compatible with polymetallic ores
The specially developed coconut shell granular activated carbon (Φ3–6 mm; iodine value ≥1000 mg/g; hardness ≥95%) is tailored for polymetallic paragenetic ores. 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 (Au adsorption capacity: 500 mg/g; Cu adsorption capacity: 700 mg/g).
Environmental compliance; elimination of heavy metal risks
Heavy metal concentrations in tailings from the activated carbon process are <0.01 mg/L (1/100th of traditional process levels), fully meeting global standards such as China’s GB 25466-2010 and the EU’s 2010/75/EU. A lead-zinc mine using this process incurred no further fines for excessive heavy metal levels.
Controllable costs; high cost-effectiveness over the full lifecycle
Activated carbon: Regenerable 3–5 times (regeneration cost is only 30% of new carbon); initial investment is just RMB 6–10 million per 1 million tons of annual ore processing capacity; annual operating costs are reduced by 68.75% (e.g., a copper mine saved RMB 55 million annually).
Safety costs: Reduced from RMB 800,000/year to RMB 150,000/year (an 81.25% decrease).
Resource maximization; unlocking the value of polymetallic ores
Copper recovery rates for polymetallic paragenetic ores increased from <50% to >95%, and gold recovery rates rose from <20% to >90%. Following implementation at a copper-zinc mine, polymetallic reserves increased from 3 million tons to 5 million tons, extending the mine's operational life by 20 years.

X. Cost Analysis

Comparison of costs between the activated carbon process and the traditional process, based on an annual processing capacity of 1 million tons of copper-zinc paragenetic ore: 

Item	Activated carbon adsorption-desorption process	Flotation and solvent extraction process
Initial investment (10,000 RMB)	600-1000	400-600
Operating costs (RMB/tonne of ore)	25-30	80-100
Maintenance costs (10,000 RMB/year)	50-100	200-300
Full life-cycle costs (RMB/tonne of ore)	50-60	150-200
Safety costs (10,000 RMB/year)	15-20	80-100
By-product revenue (10,000 RMB/year)	500-800	0

11. Why Choose Us?

Proven Track Record: We serve metallurgical clients such as Jiangxi Dexing Copper Mine, BASF (Germany), and Kennecott Copper (USA). Our activated carbon has earned unanimous acclaim for delivering high polymetallic recovery rates and ensuring environmental compliance. Notably, after adopting our coconut shell carbon, a copper-zinc polymetallic mine saw its gold recovery rate jump from 18% to 92%, resulting in an additional 6.6 tons of annual gold production valued at over RMB 2 billion.
Technical Expertise: We collaborate with the Beijing General Research Institute of Mining and Metallurgy (State Key Laboratory of Mineral Processing Science and Technology) to develop products like coconut shell granular activated carbon and thiourea-impregnated modified carbon. These are specifically engineered to address the challenges of separating polymetallic ores while meeting strict environmental standards; our coconut shell carbon’s combination of high adsorption capacity and superior mechanical strength perfectly aligns with the metallurgical industry's requirements.
Global Service: With production bases in Shanxi, Ningxia, and Fujian (total annual capacity of 45,000 tons), we offer "customized production plus 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.