Steel Mills

I. Customer Pain Points

The sintering, ironmaking, and steelmaking processes in steel plants generate high-concentration, multi-component flue gas, presenting three core challenges: "compliance difficulties," "severe corrosion," and "high costs."
Stricter emission standards; "legacy processes" fail to achieve simultaneous compliance
China’s *Emission Standards of Air Pollutants for Sintering and Pelletizing Industry* (GB 28662-2012) mandate limits of SO₂ ≤ 50 mg/m³, NOₓ ≤ 100 mg/m³, and particulate matter ≤ 20 mg/m³, while the EU’s *Industrial Emissions Directive* (2010/75/EU) imposes even stricter limits (SO₂ ≤ 30 mg/m³, NOₓ ≤ 40 mg/m³). However, the traditional "limestone-gypsum desulfurization + SCR denitrification" process targets only specific pollutants; it cannot simultaneously remove SO₃ (acid mist at 10–50 mg/m³), heavy metals (Hg at 0.1–1 mg/m³), or dioxins (0.1–1 ng TEQ/m³). Consequently, enterprises frequently face fines for exceeding limits on these co-pollutants (in 2022, China recorded 800 cases of penalties for steel flue gas limit violations, with an average fine of RMB 600,000).

Severe equipment corrosion threatens unit service life

SO₃ combines with water to form sulfuric acid mist (H₂SO₄ at 10–30 mg/m³), corroding electrostatic precipitators at the sintering machine inlet and induced-draft fans (corrosion rate > 0.1 mm/year). Traditional processes lack designs for the simultaneous removal of SO₃, leading to an unplanned equipment shutdown rate of 8% (based on 2022 statistics for the Chinese steel industry), with losses exceeding RMB 3 million per shutdown event. High operating costs make the "activated carbon + regeneration" model unsustainable.
Traditional activated carbon desulfurization and denitrification processes require an "adsorption → steam regeneration → sulfuric acid recovery" cycle. Regeneration costs are ≥0.5 RMB/kg SO₂, and catalyst (vanadium-titanium-tungsten) replacement costs are ≥200 RMB/m³. For a steel plant with an annual output of 10 million tons, annual desulfurization and denitrification costs exceed 40 million RMB, accounting for 12% of total operating costs.
Persistent pollutants such as dioxins face restrictions under international conventions.
Steel sintering flue gas contains dioxins (PCDD/Fs, with toxicity equivalents of 0.1–1 ng TEQ/m³), necessitating compliance with the *Stockholm Convention* (≤0.1 ng TEQ/m³). Traditional processes achieve dioxin removal rates of <50%, failing to meet international compliance standards (e.g., the EU's 2010/75/EU directive requiring ≤0.1 ng TEQ/m³).

II. Application Objectives

Steel plants adopt activated carbon technology with four core objectives, centering on compliance, cost reduction, safety, and adherence to international conventions:
Strict compliance and mitigation of global regulatory risks
Meeting standards for:
China GB 28662-2012: SO₂ ≤50 mg/m³, NOₓ ≤100 mg/m³, Particulate Matter ≤20 mg/m³;
EU 2010/75/EU: SO₂ ≤30 mg/m³, NOₓ ≤40 mg/m³, Dioxins ≤0.1 ng TEQ/m³;
*Stockholm Convention*: Dioxins ≤0.1 ng TEQ/m³.

• Synergistic multi-pollutant removal and elimination of equipment corrosion

Activated carbon removes SO₂, NOₓ, SO₃, Hg, and dioxins through a synergistic "adsorption + catalysis" process. The SO₃ removal rate exceeds 95% (reducing acid mist concentration to <1 mg/m³), thereby lowering the corrosion rate of induced draft fans to <0.02 mm/year and reducing the unplanned downtime rate to <2%. **Reducing Costs and Replacing Energy-Intensive Processes**
The operating cost for activated carbon (specifically lignite-based activated coke) is merely 0.2–0.4 RMB/kg of SO₂ (one-third that of the limestone-gypsum method). Furthermore, it can be regenerated 3–5 times (with regeneration costs at 30% of the price of fresh carbon). For instance, a steel plant with an annual capacity of over 10 million tons saw its annual desulfurization and denitrification costs drop from 40 million RMB to 12 million RMB—a 70% reduction.

• Meeting International Conventions and Expanding into Overseas Markets

Activated carbon achieves an efficiency of over 99% in the adsorption and catalytic decomposition of dioxins (converting PCDD/Fs into CO₂ and H₂O). This ensures compliance with the Stockholm Convention and facilitates market entry into the EU and the US (e.g., after implementation, one steel plant reduced dioxin emissions to 0.05 ng TEQ/m³ and successfully obtained EU CE certification).

III. Application Significance

The application of activated carbon in steel plant flue gas treatment serves as a core pillar for enterprises aiming to ensure regulatory compliance, reduce costs and boost efficiency, and expand internationally:
Compliance Baseline: 70% of global cases involving excessive steel flue gas emissions stem from a failure to adopt "synergistic treatment" processes. Activated carbon is one of the few technologies capable of simultaneously removing SO₂, NOₓ, SO₃, Hg, and dioxins at a controllable cost; it directly determines whether an enterprise can secure discharge permits and international orders.
Safety Assurance: Between 2021 and 2022, 50% of unplanned shutdowns in Chinese steel plants were caused by SO₃ corrosion of induced-draft fans. The "synergistic SO₃ removal" design inherent to activated carbon technology can reduce the unplanned shutdown rate from 8% to less than 2%, preventing a loss of 3 million RMB per incident.
Cost Optimization: A case study of a steel group shows that adopting the "activated coke desulfurization and denitrification" process reduced annual operating costs by 70% (cutting limestone consumption by 80% and catalyst replacement frequency by 50%), effectively increasing annual profits by 28 million RMB. International Expansion: After adopting activated carbon, a steel plant reduced its dioxin emissions to 0.05 ng TEQ/m³—meeting EU standards—and increased its export volume by 20% (from 500,000 to 600,000 tons per year).

IV. Application History

The use of activated carbon for flue gas treatment in steel plants has become increasingly widespread, driven by a combination of stricter emission standards and international regulatory mandates:
1990s: Initial Stage
Germany’s ThyssenKrupp pioneered the use of activated coke (lignite-based) to treat sintering flue gas (with an SO₂ concentration of 1,000 mg/m³). Utilizing a "moving-bed adsorption plus thermal regeneration" process, it achieved a desulfurization efficiency of 95%, marking the first industrial-scale application of activated carbon desulfurization technology.
2000s: Promotion Stage
China’s "11th Five-Year Plan" prioritized the desulfurization and denitrification of steel plant flue gas, promoting "combined activated carbon processes." In 2008, a steel plant with an annual capacity of over 10 million tons adopted activated coke, reducing SO₂ concentrations from 1,000 mg/m³ to 30 mg/m³ and becoming the first project in China to meet the compliance standards.
2010s: Upgrading Stage
The implementation of the EU Industrial Emissions Directive (2010/75/EU)—mandating SO₂ levels ≤30 mg/m³ and dioxin levels ≤0.1 ng TEQ/m³—drove the adoption of modified activated carbon (impregnated with NH₃ or K₂O). In 2015, a German steel plant using modified carbon increased its NOx removal rate from 60% to 85% and achieved a dioxin removal rate exceeding 99%.
2020s: Intelligent Stage
China’s "14th Five-Year Plan for the Development of the Iron and Steel Industry" mandates a synergistic flue gas treatment rate of ≥90%. Activated carbon systems integrated with "online monitoring and automatic regeneration" enable precision adsorption (e.g., automatically adjusting the movement speed of activated coke based on SO₂ concentration), thereby reducing operating costs by 20%. V. Mechanism of Action
Activated carbon addresses the challenges of "multi-pollutant, high-concentration, and highly corrosive" flue gas from the iron and steel industry through a triple-action process: physical adsorption, chemical catalysis, and synergistic regeneration.
1. Physical Adsorption: "Broad-spectrum sieving" via pore structure
Micropores (<2 nm): Account for 60%–70% of total pore volume; adsorb small-molecule pollutants (SO₂: molecular diameter ≈0.36 nm; NO: ≈0.317 nm; Hg⁰: ≈0.3 nm) via van der Waals forces, with an adsorption capacity of 200–300 mg/g (five times that of limestone).
Mesopores (2–50 nm): Act as "transport channels," allowing medium-sized pollutants (SO₃: ≈0.4 nm; dioxins: ≈1.0 nm) to diffuse into micropores; simultaneously adsorb heavy metal Hg (molecular diameter ≈0.3 nm).
Macropores (>50 nm): Act as "entry channels," allowing large fly ash particles (>1 μm) to enter the activated carbon interior, though they contribute minimally to adsorption.
2. Chemical Catalysis: "Targeted conversion" via surface functional groups
SO₂ Removal: Basic functional groups (e.g., pyranone, pyridinone) on the activated carbon surface adsorb SO₂; this is followed by catalytic oxidation (involving O₂) to convert SO₂ into SO₃, which ultimately combines with water to form H₂SO₄ (stored within the activated carbon pores).
NOₓ Removal: Activated carbon loaded with NH₃ converts NOₓ into N₂ via Selective Catalytic Reduction (SCR) at reaction temperatures of 120–150°C, achieving a removal rate of >85% (without the need for additional catalysts).
Dioxin Removal: Chlorine-containing functional groups (-Cl) on the activated carbon surface immobilize dioxins (PCDD/Fs) via chemisorption; subsequent thermal regeneration (400–500°C) decomposes them into CO₂ and H₂O, achieving a removal rate of >99%. 3. Synergistic Regeneration: A "Key Step" to Cost Reduction
Saturated activated coke undergoes thermal regeneration (400–500°C under inert gas protection), where H₂SO₄ is desorbed as SO₂ (10–15% concentration) and sent to a sulfuric acid plant to produce concentrated sulfuric acid (98%); mercury (Hg) is concentrated in the regeneration residue with a recovery rate exceeding 90%. The regenerated coke retains up to 80% of the adsorption capacity of fresh coke, while costing only 30% of the price of fresh coke.

VI. Application Methods

Steel plants employ a combined process—"activated coke moving bed (primary treatment) + ammonia injection (denitrification) + thermal regeneration (by-product recovery)"—to address scenarios characterized by high pollutant concentrations, multiple pollutants, and high corrosivity:
1. Activated Coke Moving Bed: Primary Treatment Unit (SO₂, SO₃, Hg, Dioxins)
Applicable Scenario: Sinter machine head flue gas (SO₂: 800–1500 mg/m³; NOₓ: 300–500 mg/m³; SO₃: 20–50 mg/m³).
Process Steps:
Adsorption: Flue gas enters the moving bed adsorption tower (packed with activated coke, particle size 5–10 mm) at a flow velocity of 0.5–1.0 m/s and a contact time of 5–10 seconds. Removal rates: SO₂ >95%, SO₃ >95%, Hg >90%, Dioxins >99%.
Movement: Saturated activated coke is discharged from the bottom of the tower and sent to the regeneration system; fresh activated coke is replenished at the top.
Key Parameters:

Project			Product Technical Specifications	Testing Standards
1	shape		Φ9mm×5~12mm	GB/T 30201-2013
2	Moisture		≤3%	GB/T 7702.1-1997
3	Particle size distribution	≥11.2mm	≤2.0%	GB/T 30202.2-2013
		5.6-11.2mm	≥97.0%
		1.4-5.6mm	≤0.7%
		≤1.4mm	≤0.3%
4	Abrasion resistance		≥97%	GB/T 30202.3-2013
5	Compressive strength		≥40daN	GB/T 30202.3-2013
6	Bulk density		≤680g/L	GB/T 30202.1-2013
7	Ash content		≤15%	GB/T 7702.15-2008
8	Volatile matter content		<5%	GB/T 2001-2013
9	Ignition point		≥430℃	GB/T 7702.9-2008
10	Iodine value		≥400mg/g	GB 7702.15-1987
★11	Desulfurization capacity		≥24mg/g	GB/T 30202.4-2013
★12	Denitrification rate		≥45%	GB/T 30202.5-2013

Regeneration cycle: 6–12 months (adjusted based on flue gas concentration).
2. Ammonia injection: Denitrification (NOₓ) auxiliary unit
Applicable scenario: Flue gas with low NOₓ concentration (<300 mg/m³).
Process steps:
Ammonia solution (5–10%) is injected at the adsorption tower inlet; an SCR reaction with NOₓ occurs on the activated carbon surface (120–150°C), achieving a NOₓ removal rate of >85%.
3. Thermal regeneration system: By-product recovery (concentrated sulfuric acid, Hg)
Applicable scenario: Regeneration of saturated activated coke.
Process steps:
Heating: Saturated activated coke is fed into the regeneration furnace (400–500°C, N₂ atmosphere); H₂SO₄ is desorbed and converted into SO₂ (concentration 10–15%).
Conversion: SO₂ is sent to a sulfuric acid plant to produce concentrated sulfuric acid (98%); Hg in the regeneration residue is concentrated and processed into HgS residue (recovery rate >90%).

VII. Application Process

Example: A steel plant with an annual capacity of over 10 million tons (sintering machine head flue gas flow: 1.2 million m³/h; SO₂: 1000 mg/m³; NOₓ: 400 mg/m³; SO₃: 30 mg/m³; Dioxins: 0.2 ng TEQ/m³):
Pre-treatment: Electrostatic precipitator (removes fly ash; efficiency 99.5%; fly ash concentration reduced to <50 mg/m³).
Main treatment: Activated coke moving-bed adsorption towers (2 units, used alternately; 800 tons of coke per unit; particle size 5–10 mm) → Ammonia injection system (5% ammonia solution; injection rate 15 m³/h).
Regeneration system: Thermal regeneration furnace (400°C, N₂ atmosphere) → Sulfuric acid plant (SO₂ converted to 98% concentrated sulfuric acid) → Hg recovery unit (regeneration residue processed into HgS residue). Emissions: Stack (SO₂ < 30 mg/m³, NOₓ < 40 mg/m³, SO₃ < 1 mg/m³, Dioxins < 0.05 ng TEQ/m³).

VIII. Application Effects

Following the retrofit of a steel plant with an annual capacity of over 10 million tonnes, key performance indicators improved significantly (based on actual operational data): 

Parameter	Pre-retrofit (Limestone-Gypsum + SCR)	After Modification (Activated Coke + Aqueous Ammonia)	Improvement Magnitude	Compliance Status
SO₂ (mg/m³)	50	＜30	Reduced by 40%	Complies with GB 28662-2012
NOₓ (mg/m³)	100	＜40	Reduced by 60%	Complies with GB 28662-2012
SO₃ (mg/m³)	30	＜1	Reduced by 96.7%	Eliminates equipment corrosion
Dioxins (ng TEQ/m³)	0.2	＜0.05	Reduced by 75%	Complies with the Stockholm Convention
Annual operating cost (10,000 RMB)	4000	1200	Reduced by 70%	—
Unplanned downtime rate	8%	＜2%	Reduced by 75%	—
Annual by-product revenue (10,000 RMB)	0	150	—	Complies with circular economy standards

IX. Core Advantages

Customized solutions for steel plants offering four irreplaceable advantages:
Highly targeted product tailored to steel flue gas characteristics
The developed lignite-based activated coke (particle size: 5–10 mm; iodine value: ≥800 mg/g; strength: ≥90%) is specifically designed for steel flue gas. Its pore structure is dominated by micropores and mesopores (micropores account for 65%), and its adsorption capacity is 40% higher than that of standard activated carbon (SO₂ adsorption capacity reaches 300 mg/g).
Synergistic multi-pollutant removal and elimination of equipment corrosion
The activated coke achieves an SO₃ removal rate of >95% (reducing acid mist concentration to <1 mg/m³), lowers the corrosion rate of induced draft fans from 0.1 mm/year to <0.02 mm/year, and reduces the unplanned downtime rate to <2%. Following implementation at a specific steel plant, no further downtime caused by corrosion occurred.
Regulatory compliance and comprehensive qualifications
The product holds ISO9001 (Quality) and ISO14001 (Environmental) certifications and complies with the GB/T 30201-2013 standard (*Activated Carbon for Flue Gas Desulfurization*), fully meeting major global emission standards for steel flue gas, including those of China, the EU, and the USA.
Controllable costs and high cost-effectiveness over the full lifecycle
Activated coke: Can be regenerated 3–5 times (regeneration cost is only 30% of new carbon); initial investment is just RMB 8–15 million for a 10-million-ton capacity steel plant; annual operating costs are reduced by 70% (e.g., one steel plant saved RMB 28 million annually).
By-products: Annual revenue of RMB 1.5 million from concentrated sulfuric acid and RMB 0.3 million from mercury (Hg) recovery, offsetting 10% of operating costs.

X. Cost Analysis

Cost comparison between the activated coke process and traditional processes, using a 10-million-ton capacity steel plant as an example: 

Project	Activated Coke + Aqueous Ammonia Process	Limestone-Gypsum + SCR Process
Initial Investment (10,000 CNY)	800-1500	500-1000
Operating Cost (CNY/kg SO₂)	0.2-0.4	0.6-0.8
Maintenance Cost (10,000 CNY/year)	100-200	300-500
Life-Cycle Cost (CNY/kg SO₂)	0.5-0.8	1.5-2.0
By-product Revenue (10,000 CNY/year)	150-200	0

11. Why Choose Us?

Proven Track Record: We serve major steel clients such as Baowu Steel, HBIS Group, and Ansteel Group. Our activated carbon solutions—recognized for their cost-effectiveness and ability to simultaneously remove multiple pollutants—have earned unanimous praise. Notably, a steel plant with an annual capacity of over 10 million tons reduced its annual operating costs by 70% and cut unplanned downtime to less than 2% after adopting our activated coke.
Technical Expertise: We collaborate with the University of Science and Technology Beijing (State Key Laboratory of New Technology for Iron and Steel Making) to develop specialized products—such as lignite-based activated coke and NH₃-impregnated modified carbon—designed to tackle the challenges of high pollutant concentrations, multi-pollutant emissions, and high corrosivity in steel industry flue gas. Our activated coke delivers high adsorption capacity and superior SO₃ removal rates, perfectly aligning with the industry's requirements.
Global Service: We operate production bases in Shanxi, Ningxia, and Fujian (with a combined annual capacity of 45,000 tons), enabling customized production and localized distribution. For overseas clients, we provide comprehensive end-to-end services—including product selection, process design, and guidance on by-product recovery—while guaranteeing a response to inquiries within 72 hours.