What are the benefits of using Ferro Silicon 72 in steel production?

Ferro Silicon 72 is a binary ferroalloy with a silicon content of 70%-74% and an iron content of 25%-29%. Its impurity content conforms to GB/T 2272-2017 standard (Al≤1.0%, S≤0.05%, P≤0.04%). Its core characteristics support its suitability for steelmaking:

 Melting point: approximately 1260℃, lower than FeSi75 (1280℃), resulting in faster dissolution in molten steel (complete dissolution in 5-8 minutes);
 Low free energy of reaction between silicon and oxygen, resulting in strong deoxidation activity. Furthermore, its balanced silicon content balances deoxidation efficiency and cost;
 Physical state: blocky (10-50mm) or granular (1-10mm), adaptable to the feeding requirements of various steelmaking equipment.

(1) High-efficiency deoxidation: Improving the purity of molten steel and reducing defects

72FeSi optimizes the quality of molten steel through a dual action of "precipitation deoxidation + slag collection and purification":

Deoxidation mechanism:

Silicon reacts with FeO in the molten steel (Si + 2FeO → SiO₂ + 2Fe), generating SiO₂ with a density of 2.65 g/cm³, much lower than that of molten steel (7.8 g/cm³), making it easy to float and be removed with the slag; at the same time, SiO₂ can form low-melting-point composite slag (melting point around 1400℃) with CaO and Al₂O₃, enhancing the slag's ability to adsorb inclusions.

Quantitative Effect:

When added at 0.3%-0.7% of the molten steel mass, the oxygen content of the molten steel can be reduced from 80-100 ppm to 30-50 ppm, and the deoxidation efficiency is 30% higher than that of traditional ferrosilicon (such as FeSi65). Data from a steel plant's converter steelmaking application shows that after using FerroSilicon72, the scrap rate caused by oxide inclusions decreased from 1.2% to 0.3%, and the billet qualification rate increased by 0.9 percentage points.

Process Adaptability:

In converter steelmaking, it can be used as a pre-deoxidizer (added before tapping) or a final deoxidizer (added during tapping). In LF furnace refining, it can be used for deep deoxidation, adapting to the needs of different smelting stages.

(2) Precision Alloying: Customizing the Mechanical and Functional Properties of Steel

FeSi alloy 72 achieves precise optimization of steel properties through solid solution strengthening and composition control:

Strengthening Mechanism:

After silicon atoms dissolve in the ferrite lattice, they induce lattice distortion, hindering dislocation movement and refining the grains (grain size decreases from 50μm to 30-40μm), significantly improving the strength and hardness of the steel.

Application Effects of Different Steel Grades:

 45# High-Quality Carbon Structural Steel:Adding Ferro Silicon alloy 72 controls the silicon content in the steel to 0.17%-0.37%, increasing the tensile strength from 600MPa to 690-720MPa (an increase of 15%-20%), and the yield strength from 355MPa to 410-430MPa;

 Silicon Steel (Electrical Steel):For every 1% increase in silicon content, iron loss decreases by approximately 10%, and magnetic permeability increases by 15%. 72%FeSi allows for precise control of the silicon content in silicon steel to 2.0%-3.5%. When used in transformer cores, it reduces core losses by 20%-25% and improves power transmission efficiency by 3%-5%.

 Low-alloy high-strength steel (such as Q345):Adding FeSi72% to supplement silicon to 0.2%-0.5% increases tensile strength by 10%-12% without reducing toughness (elongation remains ≥21%), making it suitable for engineering structural components.

(3) Cost Optimization: Reducing Overall Production Energy Consumption and Expenses

FeSi72's cost-effectiveness advantage permeates the entire steelmaking process, achieving cost reduction and efficiency improvement:

Raw Material Cost Advantage:

The unit silicon cost is 8%-10% lower than FerroSilicon 75 and 15%-20% lower than FeMn alloy. A medium-sized steel plant (annual capacity of 1 million tons) saved over 20 million yuan in raw material costs annually after replacing some high-cost alloys with FeSi72;

Energy Consumption Optimization:

Due to its low melting point and rapid dissolution, it can shorten smelting time by 10%-15%, reduce electric arc furnace steelmaking electricity consumption per ton of steel by 8%-12% (approximately 60-80 kWh/ton of steel), and reduce converter steelmaking oxygen consumption by 3%-5%;

Auxiliary Material Savings:

The SiO₂ generated during deoxidation can be used as a core component of slag, reducing the amount of slag-forming agents such as lime by 15%-20%, and reducing auxiliary material costs per ton of steel by 8-12 yuan.

(4) Multi-scenario adaptability: Covering the entire steelmaking process

Ferro Silicon 72 is adaptable to multiple scenarios such as converters, electric arc furnaces, refining, and casting, with strong versatility:

Converter steelmaking:

As the main deoxidizer, it is suitable for carbon structural steels such as Q235 and Q345, with an addition amount of 0.4%-0.7%, which can quickly reduce the oxygen content of molten steel and avoid secondary oxidation;

Electric arc furnace steelmaking:

It enables deoxidation and alloying to be carried out simultaneously, suitable for alloy structural steels such as 40Cr and 20MnV, with an addition amount of 0.3%-0.6%, shortening the smelting cycle and improving production efficiency;

LF furnace refining:

Used for deep deoxidation of high-end steels such as bearing steel and spring steel, with an addition amount of 0.2%-0.4%, combined with argon stirring, it can reduce the oxygen content of molten steel to 20-30ppm, meeting high purity requirements;

Casting industry:

As a cast iron inoculant, the addition amount is a percentage of the molten iron mass. 0.2%-0.5% promotes graphitization precipitation, refines grains, and increases the impact toughness of gray cast iron by 20%-30%, making it suitable for castings such as engine blocks and machine tool beds.

(1) Precise Control of Addition Amount

 Calculated according to the target silicon content of the steel grade: Addition amount (kg/ton of steel) = (target silicon content - initial silicon content) × 1000 / (FeSi72 silicon content × silicon recovery rate), the silicon recovery rate is usually 75%-85% (slightly lower for converters, slightly higher for electric furnaces);
 Avoid excessive addition: When the silicon content in the steel exceeds 0.6%, it will lead to a decrease in the weldability of the steel and a reduction in impact toughness (the impact energy may be lower than 34J at ≤-20℃).

(2) Timing and Method of Addition

 Converter steelmaking: Add when the steel is 1/3 full and finish when it is 2/3 full, ensuring thorough mixing with the molten steel;
 Electric furnace steelmaking: Add during the later stages of furnace charge melting (molten steel temperature 1500-1550℃) to avoid silicon burn-off due to early addition;
 LF furnace refining: Add when the argon stirring intensity is controlled at 0.3-0.5 m/s to promote the flotation of deoxidation products.

(3) Storage and Quality Control

 Storage: Store in a dry and ventilated environment to avoid moisture oxidation (oxidation will form a SiO₂ film on the surface, reducing deoxidation activity). The storage period should not exceed 6 months;
 Quality Inspection: Before use, test the silicon content and impurities using a spectrometer to ensure compliance with GB/T 2272-2017 standards, avoiding the impact of composition fluctuations on steelmaking results.