Applications of Silicon-Manganese Alloy, Ferrosilicon, and Silicon Manganese

Applications of Silicon-Manganese Alloy, Ferrosilicon, and Silicon Manganese

Silicon-manganese alloy is an important type of ferroalloy, widely used in the iron and steel smelting industry. Ferroalloys are generally classified into several series based on their composition and function, such as silicon-based, manganese-based, and chromium-based alloys. Ferrosilicon and silicon manganese are the most commonly used ferroalloy materials in steelmaking, primarily as deoxidizers and alloying additives to remove harmful elements such as oxygen and sulfur from molten steel, thereby improving the quality and performance of the steel. In addition, the silicon element in ferrosilicon can also be used in the smelting of metallic magnesium.

Silicon manganese alloy is an alloy composed of manganese, silicon, iron, and small amounts of carbon and other elements. It is a widely used and high-volume ferroalloy. It is a commonly used composite deoxidizer in steelmaking, with a significant deoxidizing effect, and also a reducing agent in the production of metallic manganese from low-carbon iron and the electrosilicon thermal process. Silicon-manganese alloy can be smelted continuously in large, medium, and small submerged arc furnaces. Silicon-manganese is abundant in southwestern China, including Yunnan, Guizhou, Guangxi, and Hunan. Raw materials for producing silicon-manganese alloy include manganese ore, manganese-rich slag, silica, and coke.

Ferrosilicon is an iron-silicon alloy composed of iron and silicon. It is produced by smelting coke, steel scrap, and quartz (or silica) in an electric furnace. Because silicon and oxygen readily combine to form silicon dioxide, ferrosilicon is commonly used as a deoxidizer in steelmaking. Furthermore, the large amount of heat released during SiO2 formation contributes to both deoxidation and increased steel temperature. Ferrosilicon is also widely used as an alloying element in low-alloy structural steel, spring steel, bearing steel, heat-resistant steel, and electrical silicon steel. In ferroalloy production and the chemical industry, it is frequently used as a reducing agent.

I. Application as a Deoxidizer

In steelmaking, molten iron is typically decarburized and impurities such as phosphorus and sulfur are removed through oxygen blowing or the addition of oxidants. However, during this process, the oxygen content in the molten steel continuously increases, with oxygen primarily existing as FeO. If oxygen cannot be effectively removed, it will severely affect the mechanical properties and internal quality of the steel billet.

Therefore, it is necessary to add elements with strong affinity for oxygen and easy slag discharge to molten steel for deoxidation. The order of element affinity for oxygen from weakest to strongest is: chromium → manganese → carbon → silicon → vanadium → titanium → boron → aluminum → zirconium → calcium.

For this reason, commonly used deoxidizing ferroalloys in steelmaking are mainly composed of elements such as silicon, manganese, aluminum, and calcium, with ferrosilicon and silicon-manganese alloys being the most important deoxidizing materials.

II. Role as Alloying Agents

Silicon-manganese alloys not only have deoxidizing functions but can also be used as important alloying additives. The addition of alloying elements can not only reduce the impurity content in steel but also precisely control the chemical composition of the steel, thereby improving the overall performance of the steel.

Common alloying elements include: silicon, manganese, chromium, molybdenum, vanadium, titanium, tungsten, cobalt, boron, niobium, etc.

Different types and amounts of alloying elements result in significant differences in the strength, toughness, wear resistance, heat resistance, and processing performance of steel, thus meeting the needs of different industrial sectors.

III. Uses as Reducing Agents

Ferrosilicon can also act as a reducing agent in ferroalloy production. For example:

Ferrosilicon can be used to produce ferromolybdenum, ferrovanadium, and other ferroalloys;

Silicon-chromium alloys can be used as reducing agents for medium- and low-carbon ferrochrome;

Silicon-manganese ferroalloys can be used for the refining production of medium- and low-carbon ferromanganese.

This characteristic makes ferrosilicon and silicon-manganese alloys equally important in the field of deep processing of ferroalloys.

IV. Factors Affecting Prices

(1) Factors Affecting the Price of Manganese Silicon

① Manganese ore price. Regarding the main ferroalloys—manganese, chromium, and silicon—while domestic resources of silica are abundant and inexpensive, manganese ore, due to its lower grade, higher mining costs, and limited reserves, requires imports for about one-third of its production. Manganese ore accounts for a significant portion of the production cost of ferromanganese alloys. my country is extremely short of chromium ore resources and relies almost entirely on imports, making it a substantial component of the cost structure of ferrochrome.

② Electricity and coke prices. The production cost of ferromanganese alloys mainly consists of the procurement costs of manganese ore, electricity, and coke. Manganese ore costs account for approximately 55%-60%, electricity costs for approximately 20%-30%, and coke costs for approximately 10%-15%. Furthermore, many companies, in addition to using domestically produced low-phosphorus, low-iron, low-sulfur, and low-silicon manganese ore, purchase a blend of imported and domestic ores for smelting to improve the grade of raw materials entering the furnace, increase manganese recovery, and reduce electricity consumption and production costs.

(2) Factors Affecting Ferrosilicon Prices

① Raw Material Prices. Ferrosilicon is an iron alloy synthesized from silicon, iron, and coke. Its price is naturally affected by the prices of these raw materials. Rising raw material prices increase the cost of synthesizing ferrosilicon, thus raising its price.

② Ferrosilicon Production. The production volume of ferrosilicon determines the market supply, which in turn affects its market price.

③ Import and Export Volume. The volume of ferrosilicon imports and exports in my country also affects the domestic price.

④ National Policies. A series of relevant national policies also affect ferrosilicon prices, such as environmental protection policies and import/export tariffs.

V. Comprehensive Role and Importance

In summary:

Silicon significantly improves the elasticity, magnetic conductivity, and strength of steel;

Manganese reduces the brittleness of steel, improves hot working performance, and simultaneously increases the strength, hardness, and wear resistance of steel.

Manganese is an indispensable basic functional raw material for producing high-quality steel. In the steelmaking process, manganese not only effectively removes harmful impurities such as sulfur and oxygen, but also comprehensively improves the quality of steel by enhancing its physical properties. Currently, the role of manganese in steel production remains irreplaceable by other elements.