Views: 0 Author: Site Editor Publish Time: 2025-12-24 Origin: Site
The industrial silicon and ferrosilicon sectors belong to the group of high-energy-consumption metallurgical industries, relying on large amounts of silica, coke, and occasionally steel scrap. These raw materials are smelted in submerged arc furnaces, with China being one of the world’s largest production bases.
While industrial silicon is essential for the photovoltaic and semiconductor industries, ferrosilicon remains a critical material for steelmaking—serving as a powerful deoxidizer, alloying agent, and a key additive in casting as an inoculant or nodulizer.
However, the industry faces two major challenges:
Low resource utilization, leading to large quantities of by-products and waste
Low thermal efficiency of submerged arc furnaces, contributing to energy loss and environmental pressure
As a result, substantial volumes of silicon slag, silica fume, high carbon silicon, and other by-products are generated. Recycling and reusing these materials not only reduces environmental impact but also creates significant economic value.
Silicon slag is generated during both industrial silicon and ferrosilicon production. For every ton of ferrosilicon produced, roughly 100 kg of silicon slag is formed. This material contains around 15–20% metallic silicon, making it a valuable resource if recycled properly.
In many factories, silicon slag has historically been stockpiled or used for low-value applications such as road paving—a practice that wastes its real potential. Modern metallurgy has revealed that silicon slag contains:
Silicon metal
Silicon oxide
Calcium oxide
Aluminum oxide
Trace alloy residues
With proper processing, the recoverable metallic silicon can significantly reduce production costs for silicon metal producers and lower environmental emissions.
Due to its high viscosity and poor fluidity, silicon slag solidifies with silicon wrapped inside molten waste materials. Advanced recovery technologies now enable producers to extract silicon efficiently by combining thermal treatment, mechanical crushing, and slag separation methods.
Crushing
Silicon slag is broken down using a jaw crusher and a sanding/beating machine.
Re-selection
Crushed materials are processed on a shaker table to separate silicon-rich fractions.
Smelting in a Ladle
Concentrated slag is melted, and silicon is separated via heating and argon stirring.
Electromagnetic Separation + Slag Refining
Aluminum: 98%
Boron: 68.5%
Iron: 81.5%
Titanium: 82.3%
Phosphorus: 36.8%
Heating power: 15 kW
Holding time: 60 minutes
Silicon recovery rate: up to 96%
Impurity removal:
These figures demonstrate that silicon slag is far from “waste”—it is a recoverable resource with considerable economic value.
Another growing use of silicon slag is the production of silicon slag briquettes, especially when the slag contains a notable proportion of silicon carbide.
Raises furnace temperature
Improves slag discharge efficiency
Enhances pig iron grade
Improves molten iron fluidity
Enhances wear resistance and machinability
In small and medium-sized foundries, silicon slag briquettes can even replace ferrosilicon, offering significant cost savings. Today, silicon slag briquette production has developed into a stable and mature industry.
Silica fume is generated during industrial silicon and ferrosilicon smelting, consisting mainly of ultrafine SiO₂ particles. For every ton of silicon metal, around 300 kg, and for every ton of ferrosilicon, about 200 kg of silica fume is formed.
In 2019, with China producing 2.2 million tons of silicon metal and 5.49 million tons of ferrosilicon, the theoretical silica fume output exceeded 1.75 million tons. However, due to outdated dust-removal equipment, many plants recover less than one-third, resulting in significant waste.
High-quality silica fume (Norway, USA): hundreds to thousands of dollars per ton
China-produced silica fume: tens to low hundreds of dollars per ton, depending on SiO₂ content and particle size
Concrete admixture: improves density, impermeability, and durability
Refractories: enhance strength and high-temperature performance
Cement and mortar enhancement
High-grade castables and ceramics
Modern dust-collection systems—bag filters and electrostatic precipitators—can recover up to 99% of silica fume, turning a once-ignored waste into a profitable product.
High carbon silicon is formed when raw materials in the lower part of the silicon furnace fail to fully react, typically due to insufficient arc heat. This material contains silicon, carbon, and trace ferroalloys.
Can partially replace ferrosilicon
Lowers alloying cost
Offers stable deoxidizing and alloying performance
Helps optimize furnace burden ratios
Produces measurable economic benefits
As steel mills seek more cost-efficient alloying strategies, high carbon silicon is rapidly gaining global attention.
Aside from silicon slag, silica fume, and high carbon silicon, ferroalloy producers also generate other by-products that can be converted into value-added materials. By adopting modern recycling technologies, producers can:
Improve resource utilization rates
Reduce environmental pollution
Lower production costs
Create new revenue streams
Efficient recycling is no longer optional—it is the key to sustainable development in the industrial silicon and ferrosilicon industries.
