How To Control The Quality Of Atomised Ferrosilicon Products?
Quality Control of Raw Materials
Strict Screening of Ferrosilicon Raw Materials
The purity of ferrosilicon raw materials is crucial to the quality of atomised ferrosilicon. During procurement, it should be ensured that the silicon content, iron content, and impurity (such as aluminum, calcium, phosphorus, etc.) contents of ferrosilicon raw materials meet the predetermined standards. For example, for atomised ferrosilicon used in high-end steelmaking, the error in silicon content of ferrosilicon raw materials should be controlled within a small range, generally requiring that the fluctuation of silicon content does not exceed ±0.5% to ensure the stable performance of the final product.
Check the physical state of the raw materials and avoid using ferrosilicon raw materials with obvious inclusions or unevenness. These inclusions may affect the atomization effect during subsequent processing, resulting in uneven particle size or impure composition of the product.
Strict Screening of Ferrosilicon Raw Materials
If the ferrosilicon raw materials contain moisture, drying treatment is required. The drying process should strictly control the temperature and time. The temperature is usually set at 100 - 200 °C, and the time is determined according to the moisture content and batch size of the raw materials. Ensure that the moisture content of the raw materials is reduced to the specified level, generally less than 0.5%, to prevent defects such as pores caused by moisture during the melting process and affect the product quality.
Quality Control during the Production Process
Control of the Melting Process
- Temperature Control: When melting ferrosilicon raw materials, precise control of the melting temperature is the key. Generally, the melting temperature should be maintained at around 1300 - 1400 °C. Use high-precision temperature measurement and control systems, such as thermocouples and automatic temperature control equipment, to ensure that the temperature fluctuation is controlled within ±10 °C. If the temperature is too high, it may lead to excessive oxidation of ferrosilicon; if the temperature is too low, incomplete melting will occur, affecting the subsequent atomization effect.
- Furnace Atmosphere Control: Maintaining the stability and reducibility of the furnace atmosphere is also important. An appropriate amount of reducing gas (such as hydrogen or carbon monoxide) can be introduced into the furnace to prevent the oxidation of ferrosilicon during the melting process. Meanwhile, the composition and pressure of the furnace atmosphere should be monitored to keep them within a range conducive to the melting of ferrosilicon without oxidation reactions.
Control of the Atomization Process
- Optimization of Atomization Parameters: The parameters of the atomization process directly affect the particle size and shape of the product. For the water atomization process, the water pressure, water flow rate, and flow rate of liquid ferrosilicon should be precisely controlled. The water pressure is generally controlled within a certain range, such as 8 - 12 MPa. The water flow rate and ferrosilicon flow rate should be adjusted according to the target particle size of the product to ensure the formation of uniform tiny droplets.
- Equipment Maintenance and Monitoring: Regularly maintain and inspect the atomization equipment, including nozzles, pipelines, and pressure systems. Ensure that the nozzles have good atomization effects and no blockage or wear. Through online monitoring equipment, observe the parameter changes during the atomization process in real time, such as droplet size distribution and spray angle, and detect and solve problems in a timely manner.
Control of the Collection and Post-treatment Links
- Particle Collection and Screening: During the collection process of atomized particles, use appropriate collection devices to ensure the recovery rate of particles. After collection, screen the particles and separate particles in different particle size ranges according to product requirements. For example, for atomised ferrosilicon used in welding, it may be necessary to screen out particles with a particle size of 20 - 100 μm. Use multi-layer sieves for graded screening to ensure that the product particle size meets the requirements of specific applications.
- Standardization of Post-treatment Operations: If post-treatment is required for the collected particles, such as surface treatment or mixing with other additives, it should be carried out in strict accordance with the operating procedures. During surface treatment, control the amount of treatment agent and treatment time to ensure that the surface properties of the particles are effectively improved without introducing new impurities. When mixing additives, ensure the uniform distribution of additives. Through sufficient stirring or other mixing means, fully mix atomised ferrosilicon with additives to improve the comprehensive performance of the product.
Construction of Quality Inspection System
Chemical Composition Detection
- Adopt advanced chemical analysis methods, such as spectral analysis (atomic absorption spectroscopy, emission spectroscopy, etc.) and chemical titration methods, to accurately detect the contents of silicon, iron, and impurities in atomised ferrosilicon products. Establish a regular inspection system to ensure that the chemical composition of the product always meets the quality standards. For example, conduct a comprehensive chemical composition analysis for each batch of atomised ferrosilicon products and keep samples for re-inspection.
Physical Property Detection
- Particle Size Analysis: Use laser particle size analyzers and other equipment to detect the particle size distribution of the product. Compare the detection results with the product specification requirements. The deviation of the particle size distribution should be controlled within a certain range, such as ±10%. Meanwhile, monitor the average particle size of the product to ensure that it meets the expected application requirements.
- Particle Shape Observation: Use microscopes or electron scanning microscopes and other tools to observe the shape of particles. The ideal shape of atomised ferrosilicon is spherical. It should be ensured that most of the particles (generally requiring more than 90%) are close to spherical. Strictly control the proportion of irregularly shaped particles, because this may affect the fluidity and dispersibility of the product.
- Density Measurement: Use density meters and other instruments to measure the density of the product and ensure that the density value is within the specified range. The density deviation generally does not exceed ±0.1 g/cm³. The accuracy of density is of great significance for the performance of the product in different application scenarios (such as the uniformity of distribution in alloys)
Performance Verification Tests
- Conduct relevant performance verification tests according to the application fields of atomised ferrosilicon. For example, in steelmaking applications, conduct deoxidation tests and alloying effect tests. Through actual simulation of the steelmaking process, observe the degree of deoxidation of molten steel by the product and the improvement of steel properties (such as strength, toughness, etc.). In foundry applications, conduct fluidity and casting quality tests to evaluate the impact of the product on the foundry process and casting performance. Only through these performance verification tests can it be ensured that the product can meet the quality requirements in practical applications.
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