1.Why does the recycling value change?
Coatings as "Impurities":
Aging coatings (plastics, resins, pigments, etc.) burn and gasify during high-temperature steelmaking, producing large amounts of smoke and harmful gases (such as chloride ions from PVC coatings), increasing the environmental treatment costs and energy consumption of steel plants.
The pigments in the coating may contain metallic elements such as zinc, aluminum, and titanium. These elements, when mixed into molten steel, alter its composition, affecting the mechanical properties of the new steel and requiring more complex composition adjustments.
Coating ash forms slag, increasing steelmaking losses and auxiliary material costs.
Increased Recycling Costs:
Compared to clean plain carbon steel scrap or uncoated steel, processing coated scrap requires a more stringent waste gas treatment system. Therefore, recyclers/steel mills may lower prices due to the higher processing costs.
2.What are the specific manifestations of value changes?
Compared to high-quality scrap steel: Its value is significantly lower than that of high-quality scrap steel sheets of similar thickness and without coating (such as "heavy scrap").
Common classification: It is usually classified as "light scrap steel" or "low-grade scrap steel," with prices similar to mixed light and thin materials.
Compared to unaged color-coated coils: Even new color-coated coil scrap has a lower recycling value than clean galvanized coil scrap. After aging, the value will decrease slightly further, but not as much as the difference between "new color-coated coils" and "clean steel."
3.How do coating type and thickness affect the discount rate?
PVC plastisol coating: Due to its chlorine content, it may produce dioxins during incineration, resulting in the highest environmental treatment costs and the most significant price reduction.
Ordinary polyester/silicone-modified polyester coating: Relatively common, with a moderate price reduction.
PVDF and other high-fluorine coatings: Treatment is also more complex, with a significant price reduction.
The thicker the coating, the higher the proportion of impurities, and the greater the price reduction.
4.How does the value of the substrate affect the degree of discount?
The base of recycling value remains the steel itself. If the base material is high-strength steel, its inherent alloy components (such as manganese and niobium) have some value during recycling, which can partially offset the depreciation of the coating.
Zinc-plated base material (aluminized zinc): Zinc is an impurity in steelmaking and needs to be separated. Therefore, even uncoated galvanized coils have a lower recycling value than ordinary carbon steel. Color-coated coils, with an additional coating on the galvanized base material, are essentially "impurities on top of impurities," resulting in even lower value.
5.How about environmentally friendly recycling?
Despite the depreciation in value, steel recycling itself has extremely high environmental and economic value. Priority should be given to reputable recyclers with environmental qualifications to handle the process, avoiding pollution caused by illegal dumping or incineration.
When purchasing color-coated coils, the final recycling cost/benefit throughout their entire life cycle should be taken into consideration. Some environmentally friendly coatings (such as chromium-free and low-chlorine formulations) may be easier to recycle in the future, representing an industry trend.