Ferrosilicon Production Process

  • FS Metal
  • Jan 15, 2023
  • Blog

Ferrosilicon, an alloy of silicon and iron, is an important raw material for steel making and casting. High-purity ferrosilicon improves the physicochemical and mechanical properties of steel and castings and enhances the quality of steel and castings.

Historical Process Of Ferrosilicon

In 1810, J.J.Berzelius was the first to smelt ferrosilicon by putting quartzite, steel scrap, and coke into a calciner, thus smelting low-grade ferrosilicon with a silicon content of 2.2% to 9.3%.

In 1875, A. Pourcel successfully smelted ferrosilicon with a silicon content of 10% to 18% using a blast furnace.

In 1899, Du Cholmol smelted ferrosilicon with 25% to 50% silicon content using a mineral-heated furnace at the Holcim Rock plant in the United States.

In 1903, Kadar improved on DiCharmel's method of producing ferrosilicon and successfully smelted ferrosilicon with 75% silicon content using an electric furnace. Kadar's method of smelting ferrosilicon using electric furnaces continues to be used today, and with continuous improvements, ferrosilicon manufacturers can now smelt various grades of ferrosilicon with lower impurities and higher purity of ferrosilicon.

Historical Process Of Ferrosilicon

Ferrosilicon Raw Materials

Quartz stone For Ferrosilicon

The main raw materials for smelting ferrosilicon are quartz stone, coke, and steel scrap. To produce high-purity ferrosilicon, you need to find quartz stone with high SiO2 content, with SiO2>97% is better. Impurities in quartz stone can affect the purity of ferrosilicon, so it is necessary to assay the impurity elements in quartz stone before production. The use of quartz stone with low impurity content, good blast resistance, and particle uniformity is the key to producing high-purity ferrosilicon. In the actual smelting process, the quartz stone particle size will be determined by the furnace capacity, operating voltage, and the nature and level of operation of the reducing agent. Large electric furnaces use quartz stone sizes from 40mm to 120mm, while small electric furnaces use 25mm to 80mm.

Coke is an important carbonaceous reductant in smelting ferrosilicon, which has the characteristics of cheap price and abundant resources. The coke used in ferrosilicon smelting is mainly metallurgical coke, which is required to have a low ash content in order to produce high-purity ferrosilicon, specifically FeO≈45%, SiO2≈27%, MgO≈1.0%, Al2O3<0.4% and P2O3<0.04%.

Coke For Ferrosilicon
Steel Scrap For Ferrosilicon

Steel scrap can be SiO2 reduced from quartzite during the production of ferrosilicon. In order to ensure its reduction effect, it is therefore required that steel scrap Fe>95% and its length is less than 100 mm so that it can melt faster and absorb Si or destroy SiC. it is important to note that in order to guarantee the chemical composition and quality in ferrosilicon, it is required that no alloy type steel scrap, as well as rusted and oiled steel scrap are used. Learn more about Iron In Ferrosilicon

Basic Principles Of Ferrosilicon Smelting

Oxygen is removed from SiO2 by smelting ferrosilicon with a carbonaceous reducing agent. Using an electric furnace to create a high-temperature environment, when the quartz stone is dissolved and coke is added, the C in the coke is used to produce a chemical reaction with the SiO2 in the quartz stone to produce CO gas, which is discharged through the furnace mouth, thus reducing the Si from the quartz stone.

Ferrosilicon Production Process

The smelting of ferrosilicon using a mineral-heated furnace needs to be carried out continuously and uninterruptedly. The method is to mix quartz stone, coke, steel scrap and other raw materials and then add them to the furnace from the feeding port, and under the high temperature environment generated by the electrode and electric arc, the raw materials in the furnace continuously melt and produce chemical reactions to form a liquid alloy, and when a certain amount of liquid alloyhas accumulated in the furnace, it can be discharged from the iron outlet and cast into ferrosilicon ingots.

Ferrosilicon Production Process Flow

Quartz Stone + Coke + Steel Scrap -> Charging Into Furnace -> Smelting -> Regular Iron Discharge -> Pouring -> Fine Sieving -> Grading Into Storage

Ferrosilicon Process Cost

Smelting ferrosilicon needs to consume a lot of electrical energy, according to statistics, for every 1 ton of ferrosilicon 75 produced, about 1780Kg~1850Kg of silica, 890Kg~930Kg of coke, 220Kg~230Kg of steel scrap, 45Kg~50Kg of electrode material, and 8600~9000kW.h. The main factor affecting the cost of ferrosilicon production is electricity consumption, and due to the price of electricity continuously rise, the proportion of electricity in the cost of ferrosilicon production is getting higher and higher, which shows that if you want to reduce the production cost of ferrosilicon, you must take the low energy consumption route.