72 ferrosilicon, with approximately 72% silicon content, is a crucial ferroalloy widely used in various industries such as steelmaking, foundry, and chemical engineering. Understanding its production process is essential for both industry professionals and those interested in the field of metallurgy.
Raw Material Preparation
1
Quartzite
Quartzite serves as the primary source of silicon. High - quality quartzite with a silicon dioxide (SiO₂) content of over 97% is preferred. Low - impurity quartzite ensures a higher purity of the final product. The SiO₂ in quartzite will participate in the subsequent reduction reaction to form silicon.
2
Coke
Coke acts as the reducing agent in the production of ferrosilicon 72. It should have a high fixed - carbon content and low levels of ash, sulfur, and other impurities. Metallurgical coke and petroleum coke are commonly used. The carbon in coke reacts with the oxygen in silicon dioxide to reduce it to silicon.
3
Steel Scrap
Steel scrap is used to adjust the iron content in the alloy and also helps improve the fluidity and electrical conductivity of the slag. It should be clean, free from oil and other contaminants. The iron in the steel scrap combines with silicon to form the ferro silicon alloy.
4
Batching
Accurate batching is crucial for obtaining 72 fesi with the desired composition. Based on the required silicon and iron content in the final product, the proportions of quartzite, coke, and steel scrap are precisely calculated. Generally, quartzite accounts for a relatively large proportion, while the amounts of coke and steel scrap are adjusted according to specific production conditions. The batching process requires strict control to ensure product quality consistency.
Electric Furnace Smelting
Charging
The prepared raw materials are charged into the electric furnace in a specific order. Usually, a layer of coke is first laid at the bottom of the furnace, followed by a mixture of quartzite and steel scrap. This charging sequence helps in the smooth start of the smelting process and the efficient conduction of electricity.
Power - on and Arc - starting
Once charged, the electric furnace is powered on. An arc is generated between the electrodes and the furnace charge. The intense heat from the arc rapidly raises the temperature of the furnace charge to a molten state. During smelting, strict control of the furnace voltage, current, and power is necessary. This ensures uniform heating within the furnace and promotes the smooth progress of the reduction reaction.
Reduction Reaction
As the temperature rises, a reduction reaction occurs. The carbon in coke reacts with the silicon dioxide in quartzite, producing silicon and carbon monoxide. The chemical equation for this reaction is: SiO₂ + 2C → Si + 2CO↑. Simultaneously, the iron from the steel scrap combines with the newly formed silicon to form the fesi alloy. The reaction requires a high - temperature environment and sufficient reaction time. Therefore, maintaining a high - temperature state in the furnace and adjusting the addition of furnace charge and electrode position in a timely manner according to the reaction progress are essential.
Refining
After a certain period of smelting, the ferro silicon alloy in the furnace needs to be refined. By adjusting the composition and properties of the slag, impurities such as sulfur and phosphorus in the alloy can be further removed, thereby improving the purity and quality of the silicon ferro. During the refining process, auxiliary materials such as lime may be added to improve the fluidity and reactivity of the slag.
Casting and Shaping
When the ferrosilicon alloy reaches the required composition and temperature, the taphole of the electric furnace is opened, and the molten alloy is poured into a ladle. Care must be taken during tapping to prevent excessive contact between the molten alloy and air to avoid oxidation.
The ladle containing the molten alloy is transported to the casting area and poured into specific molds. The shape and size of the molds are determined according to the product specifications. Common molds include ingot molds and granule molds. As the molten alloy cools and solidifies in the molds, it takes on the desired shape.
Inspection and Packaging
Sampling and Inspection
Samples are taken from the cast silicon ferro products to analyze their chemical composition, physical properties, and other indicators. This ensures that the product quality meets the relevant standards for 72% ferro silicon. If the product quality does not meet the requirements, appropriate measures need to be taken for adjustment or re - processing in a timely manner.
Packaging and Warehousing
The inspected and qualified ferrosilicon products are packaged according to customer requirements. Usually, sealed packaging is used to prevent the product from getting damp or oxidized during storage and transportation. The packaged products are then stored in a warehouse, awaiting shipment.
In conclusion, the production of ferrosilicon 72% involves multiple complex steps, from raw material preparation to the final packaging of the product. Each step requires strict control and precise operation to ensure the production of high - quality 72# fesi that meets the needs of various industries.
