Views: 0 Author: Site Editor Publish Time: 2026-01-26 Origin: Site
As the name suggests, ferrosilicon is primarily composed of silicon and iron. It serves as a vital deoxidiser and alloying agent in the steel industry. Understanding its manufacturing process is crucial for ensuring product quality. This article provides an in-depth analysis of the ferrosilicon manufacturing process, covering each step from raw material preparation to the final product.
High-quality ferrosilicon begins with strict control over three key raw materials:
High Purity Requirement: The SiO₂ content should exceed 97%. Low-grade silica contains higher levels of impurities like Al₂O₃ and CaO, which require higher reaction temperatures. This increases power consumption and reduces agent efficiency while generating unwanted furnace slag.
Harmful Elements: Phosphorus and sulfur are detrimental to steel quality. Therefore, the P₂O₅ content in silica must be kept below 0.02%. Sulfur content is typically low and volatile, often dissipating during smelting.
Thermal Stability: Silica must have excellent thermal shock resistance. Material that fractures into fine pieces upon heating can severely hinder charge permeability within the furnace, especially in large-scale operations.
Particle Size: Size specifications vary by furnace capacity.
Large Electric Arc Furnaces: 40-100 mm
Smaller Furnaces: 25-80 mm
The reducing agent is critical for the chemical reaction. Metallurgical coke is the most commonly used agent in ferrosilicon production.
Composition: High fixed carbon (>84%), low ash (<14%), and low moisture (<6%) are essential for efficiency.
Particle Size: Optimal size ensures both reactivity and charge permeability.
Large Furnaces: 5-18 mm
Smaller Furnaces: 1-8 mm (with less than 20% in the 1-3 mm range)
Physical Properties: High electrical resistivity and porosity are preferred to facilitate the smelting process.
Steel scrap acts as the iron source for the alloy.
Type: Only clean, non-rusty carbon steel scrap should be used (iron content >95%). Rusty scrap introduces powder and hydrogen, impairing quality. Alloyed, non-ferrous, or pig iron scrap is prohibited.
Quality: Surface impurities must be absent to prevent contamination of the final ferrosilicon product.
The production of ferrosilicon is a continuous process conducted in a submerged arc furnace. Here are the key stages:
Raw Material Preparation & Blending: Quality starts here. Raw materials are crushed to optimal sizes and precisely blended. The charging order—coke, followed by silica, then steel scrap—is critical due to their differing bulk densities. This ensures a uniform mix and consistent furnace feed.
Smelting in the Submerged Arc Furnace: The prepared charge is fed into the furnace. Electrodes are submerged in the burden, generating intense heat. The core reduction reaction occurs:
6SiO₂ + 12C + Fe → FeSi + 5Si + 12CO
Operators meticulously control electrode depth, charge levels, and furnace temperature.
Tapping & Slag Management: Molten ferrosilicon accumulates at the furnace bottom and is periodically tapped out. While the process is designed to be slag-free, some slag (composed of Al₂O₃, SiO₂ and CaO) forms. Proficient manufacturers manage this by occasionally adding lime to flux and removing slag, protecting furnace integrity and reducing energy costs.
Casting, Cooling & Crushing: The tapped liquid ferrosilicon is collected in ladles, poured into casting beds, and allowed to cool naturally into solid blocks. These blocks are then crushed and screened into standard or customer-specified sizes (e.g., lumps, granules).
Final Packaging: The final product is typically packed in durable, 1-tonne jumbo bags for secure storage and shipment to global customers in the steel industry.
The heart of any ferrosilicon plant is the submerged arc (or electric arc) reduction furnace. It allows for continuous operation, where deep and stable electrode immersion, consistent raw material charging, and controlled tapping cycles are paramount for productivity and product uniformity.
This overview outlines the fundamental ferrosilicon manufacturing process. In practice, success hinges on expert control over countless details: precise ingredient ratios, meticulous charging sequences, adept slag handling, and precise temperature management.
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