The Chinese government and the China Manufacturing Association are actively promoting the transition to green casting products and reducing carbon emissions.

Green CastingGreen casting is a sustainable development model centered on the 3R principles of a circular economy (reduce, reuse, and recycle). Through technological innovation and management optimization, it minimizes negative environmental impacts and maximizes resource efficiency throughout the life cycle of cast products.

Amid the global manufacturing transition toward carbon neutrality, the foundry industry, a typically energy-intensive sector, is undergoing a systemic transformation from end-of-pipe pollution control to a lifecycle low-carbon approach. Based on empirical data from demonstration projects in China and combined with technical validation from leading domestic companies, this article analyzes the four-dimensional synergistic carbon reduction mechanism of "materials-processes-circulation-management." Published research indicates that the demonstration projects have reduced lifecycle carbon emissions per ton of casting to 0.13-0.25 tons of CO₂e, a 68-82% reduction compared to traditional processes (calculated according to system boundaries in GB/T 32151.21-2024). 

Ⅰ. Materials: Reconstructing a Low-Carbon Supply Chain

Breakthroughs in Hydrogen-Based Metallurgy

Using the "green electricity hydrogen production - hydrogen-based vertical furnace - smelting and refining" process, data from a company's 1.2 million-ton hydrogen metallurgy demonstration project shows that carbon emissions per ton of molten iron in the smelting stage are 0.02 tons, and after accounting for auxiliary materials, the entire process emits 0.132 tons (an 89% decrease compared to traditional blast furnaces, according to the Ministry of Industry and Information Technology's "Energy Efficiency Benchmark Values for the Steel Industry"). Essentially, this process replaces coke smelting with hydrogen reduction reactions, blocking carbon from participating in the reaction at the molecular level. 

Recycled Metal Recycling System

In aluminum alloy casting, adding ≥90% recycled aluminum can reduce the carbon factor from 8.6 kg CO₂/kg (primary aluminum, EU-28 grid) to 0.5 kg. Demonstration results from an automotive parts company show a 0.62 t CO₂ reduction per ton of aluminum casting, and the mechanical properties of recycled aluminum reach 98.2% of primary aluminum (tested according to ASTM B108).

II. Process: Thermodynamic System Optimization

Quantum Arc Furnace Technology

A specialty steel company has implemented a quantum arc furnace with three-stage waste heat recovery (flue gas-steam-thermal oil). Energy consumption per ton of molten steel has been reduced to 328 kWh (the best value in its category according to the Ministry of Industry and Information Technology's Energy Efficiency Leader Case Study), and system thermal efficiency has increased from 35% to 65%. This represents a 9.2% energy saving compared to traditional electric arc furnaces (based on a 360 kWh benchmark).

Low-NOx Combustion Technology

The smelting process utilizes oxygen-enriched combustion with flue gas recirculation, controlling NOx emissions to 48 mg/m³ (52% better than the GB 39726-2020 standard) and reducing gas consumption by 15.3%. Field tests at a die-casting company have shown a 40% reduction in denitrification catalyst usage, indirectly reducing CO₂ emissions by 0.03 t/ton of castings.

III. Circular End: Building a Closed-Loop Industrial Metabolism 

100% Waste Sand Recycling System 

A Chinese company uses a combined "thermal method + mechanical grinding" process, achieving an 85% recycled sand recycling rate (revised from the original ≥95%), reducing natural sand mining by 1.02 tons per ton of casting. The cost of recycled sand is 38% lower than that of new sand, and the tensile strength of molding sand is increased by 29% (according to ISO 15812 standards). 

Micronized Utilization of Waste Slag 

Processing smelting waste slag into cement admixtures achieves zero landfill and reduces CO₂ emissions by an additional 0.047 tons per ton of casting. This technology has formed a cross-industry carbon emission reduction accounting methodology (CCER Methodology ACM001-V02). 

IV. Management End: Digital Operation of Carbon Assets 

ISO 14067 Carbon Footprint Certification

An export company established an 18-node carbon database and obtained the EU CBAM tax exemption certificate. According to the draft transitional period for 2026, the carbon tariff cost for aluminum castings is 3.4€/tCO₂e, and for iron castings it is 1.38€/tCO₂e (revised 18% from the original estimate). Carbon data has become a core indicator for supply chain access for companies like BMW and Siemens. 

Digital Twin Optimization System 

A company built a digital twin of its casting production line, which uses AI algorithms to optimize process parameters in real time. This has resulted in a 4.7% increase in product qualification rate, a 7.9% decrease in unit energy consumption, and a 62% reduction in process commissioning cycles.

V. Practical Results and Economic Analysis

Operational data from the eight demonstration projects show:

Contribution to carbon reduction: 61.3% for materials, 24.7% for processes, 10.2% for recycling, and 3.8% for management

Payback period: The static payback period for quantum arc furnace transformation is 2.3-2.8 years (at an electricity price of 0.6 yuan/kWh)

ESG value-added effect: Participating companies have obtained an average of 3.2 low-carbon certifications from organizations such as SGS and TÜV, resulting in an 8-13% product premium

VI. Industrial Transformation Trends

Green casting is driving three Major Paradigm Shift:

Niche Upgrading: Foundries are evolving into regional circular economy hubs, such as the Hami Industrial Park, which achieves closed-loop utilization of waste sand, waste slag, and waste heat within the park.

Value Dimension Expansion: Carbon footprint data has become a new trade currency, giving rise to the "Low-Carbon Casting as a Service" (LCaaS) business model.

Technology Convergence Accelerates: Cross-sector applications such as quantum computing for optimizing melting parameters and blockchain-based carbon footprint traceability are gradually being implemented.

Conclusion

When empirical data confirms that green casting can achieve "synergistic emissions reduction and efficiency improvement," this industrial revolution has entered an irreversible phase. The China Foundry Association predicts that by 2025, the coverage rate of green technologies will reach 83%, driving a 52% reduction in the industry's carbon emissions intensity. This is not just a technological evolution; it represents a practical response by the manufacturing industry to its responsibility for sustainable development.

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