Ferroalloys

Ferroalloys are raw materials mainly used in steels production process. Ferroalloys are mostly made from charges of the nonferrous metal ore, iron ore, coke or coal, and flux by treatment at high temperature in a submerged-arc electric furnace. There are variety of ferroalloys such as Ferrosilicomanganese, Ferromanganese, Ferrovanadium, Ferrotitanium, Ferronickel, Ferromolybdenum, Ferrotungsten and Ferroniobium. Also, an aluminothermic reduction process is used for making some of the ferroalloys such as Ferrovanadium, Ferrotitanium, and Ferroniobium. Ferroalloys are added in steels to improve properties such as tensile strength, ductility, and fatigue strength and corrosion resistance. Additionally, there can be several other tasks for ferroalloys such as in refining, deoxidation, control of non-metallic inclusions and precipitation processes.

Based on their application, there are different types of ferroalloys being used in metallurgical plants. Ferroalloys are classified into two main categories: bulk ferroalloys and noble ferroalloys. Bulk ferroalloys are such as high carbon ferromanganese, medium carbon ferromanganese, low carbon ferromanganese, silicon manganese, ferrosilicon, high carbon ferrochromium, medium carbon ferrochromium and low carbon ferrochromium. Bulk ferroalloys are produced in large quantities in electric arc furnaces and are majorly used in stainless steels and carbon steels. Most of the noble ferroalloys are made from rare-earth minerals such as Ferronickel, Ferromolybdenum, Ferrovanadium, Ferrotungsten, Ferroniobium, Ferrotitanium, Ferroaluminum, Ferroboron. These are expansive to produce as compared to the bulk ferroalloys.

 

2- Desulfurizer, to remove sulphur content in molten metal as a harmful element in steels chemical composition. In fact, Mn reacts with the

remaining sulphur in steel composition, thus preventing hot shortness.

3- To add manganese element to steels chemical composition, Mn either as free element or as combined with other elements has great

influence on steels properties such as hardenability, tensile strength, workability, toughness, hardness and resistance to abrasion. 

Ferromanganese is divided to three categories as below:  

- High carbon Ferromanganese (HCFeMn):

High carbon ferromanganese is one of the most widely used ferroalloy in the world. Standard ferromanganese, also known as high carbon ferromanganese is a manganese alloy, smelted directly from manganese ores. Its manganese content ranges from 70-80 wt% and its carbon content from 6-7 wt%. High carbon ferromanganese is used as an oxidizing and alloy maker for steel. 

- Medium carbon Ferromanganese (MCFeMn): 

Medium carbon Fe-Mn can be produced by a de-carbonation process or through a redox (reduction-oxidation) reaction between silicon (Si) in silicomanganese (Si-Mn) alloy and Mn ores. Low carbon Fe-Mn is produced by the reaction of Mn ore and low carbon Si-Mn. When liquid silicon manganese is reacted with manganese ore or a high MnO rich slag, the silicon is oxidized increasing the Mn content of the alloy without an increase in the carbon content. This method is commonly used in South Africa to produce grades of refined (Medium and Low Carbon) ferromanganese with Mn 75%-80% and higher with varying carbon contents from 0.1% to 2%. The price of the alloys increases as the carbon content is reduced and unlike standard ferromanganese is usually sold per unit of manganese contained. Low carbon ferromanganese (LCFeMn) & medium carbon ferromanganese is mainly used for producing E6013, E7018 and other types of welding electrodes. 

- Low carbon Ferromanganese (LCFeMn): 

Low carbon ferromanganese contains approximately 80% of manganese and 1% of carbon with lower contents of sulphur, phosphorous and silicon. Low carbon ferromanganese is mostly used in the welding industry. It is also an essential ingredient for making high-strength low-alloy steel and stainless steels.

 

FerroSilico manganese (FeSiMn)                                                                                             Ferrosilico manganese is primarily an alloy of manganese and iron. It contains a high content of manganese and used in steels product wherein silicon content needs to be controlled at low levels. It is mainly used in the silicon manganese production of flat steel, manganese-rich steel and stainless-steel products. The standard grade ferrosilicon manganese contains14 to 16% of silico, 65 to 68% of manganese and 250% of carbon. Special grades with up to 30% Si are used in the manufacture of stainless steels.

Ferrosilico manganese is used for different purposes in steelmaking process: 

1- Deoxidizer, to remove extra oxygen content of molten metal.

2- Desulfurizer, to remove sulphur content in molten metal as a harmful element in steel chemical composition.  In fact, Mn reacts with the

remaining sulphur in steel composition, thus preventing hot shortness.

3-To add manganese and silicon elements (as alloying elements) to steel chemical composition. Mn either as free element or as

combined with other elements has great influence on steel properties such as hardenability, tensile strength, workability, toughness,

hardness and resistance to abrasion.

Si is another additive alloying element which is mainly added to steel composition in order to increase strength,  makes the metal alloy

higher ductility without breaking the metal down at high temperatures.

 

Ferrochromium (FeCr) Ferrochromium is manufactured by conducting carbothermic reduction of iron magnesium chromium oxide at high temperatures. Iron-chromium alloy is produced by the reduction of chromium ore using coal and coke. This reduction process requires heat which generates the electric arc of the furnace.

Ferrochromium is added to steel to promote different properties such as hardness, strength and to make stainless steel. High carbon ferrochromium is most commonly used in special applications such as engineering steel. Also, low carbon ferrochromium is used during steel production to adjust the chromium percentages. It is also a low-cost alternative to metallic chromium in super alloys and special melting applications and also used when more chromium is needed to be added to carbon steels. In addition, high carbon ferrochromium is used in manufacturing of ball-bearing steels, tool steels as well as other alloy steels. Apart from stainless steel, low carbon ferrochromium is also used in manufacturing of acid-resistant steels.

 

Ferrophosphorus (Fe₂P)                                                                                                  Ferrophosphorus is a byproduct of phosphorus production in submerged-arc furnaces from apatites, reduced with carbon. It is formed from iron oxide impurities. Ferrophosphorus is used mainly as an additive in foundry industry to improve floatability of foundry iron, thus improving the quality of the castings. Phosphorus content can increase wearing resistance and improve the cut ability in the castings.

Ferrophosphorus is also used as additive in the steel production, which can improve the corrosion resistivity in certain steel products. Also, it is used for an ingredient in high-strength low-alloy steel (HSLA). In addition, many organic compounds of phosphorus have various uses, including those as additives for gasoline and lubricating oil, as plasticizers for plastics. 

 

Silicon calcium (Ca2SiO4)                                                                                                          Silicon calcium, also known as slag, is produced when molten iron is made from iron ore, silicon dioxide and calcium carbonate in a blast furnace. Calcium silicate insulation is manufactured from amorphous silica, lime, reinforcing fibers and other additives that are mixed with water in a batch mixing tank to form slurry. This slurry is pumped to a pre-heater where it is heated to boiling and quickly poured into molds.

Calcium silicon is used mainly for steel production, as it allows inclusive treatments as well as deoxidizing and de-sulphuring of liquid steel. This process that we use improves inclusive properties, the fluidity of continuum casting, transversal mechanical properties and use in factories.

 

Ferromolybdenum (FeMo)                    This alloy is produced by heating a mixture of molybdenum (VI) oxide MoO3, aluminum, and iron, the oxide and the aluminium combine via an aluminothermic reaction to generate molybdenum in situ. The ferromolybdenum can be purified by electron beam melting, for alloying with steel the ferromolybdenum is added to molten steel before casting. It is added to stainless and heat-resisting steels that are used in synthetic fuel and chemical plants, heat exchangers, power generators, oil-refining equipment, pumps, turbine tubing, ship propellers, plastics and inside acid storage containers.

 

Ferrotitanium (FeTi)                                                                                                                            Ferrotitanium is a ferroalloy, an alloy of iron and titanium with between 10–20% iron and 45–75% titanium and sometimes a small amount of carbon. It is used in steelmaking as a cleansing agent for iron and steel; the titanium is highly reactive with sulphur, carbon, oxygen, and nitrogen, forming insoluble compounds and sequestering them in slag, and is therefore used for deoxidizing, and sometimes for desulfurization and denitrogenation. In steelmaking the addition of titanium yields metal with finer grain structure.

Ferrotitanium can be manufactured by mixing titanium sponge and scrap with iron and melting them together in an induction furnace. Ferrotitanium powder can be also used as a fuel in some pyrotechnic compositions. It is used in steelmaking as a cleansing agent for iron and steel, the titanium is highly reactive with sulphur, carbon, oxygen, and nitrogen, forming insoluble compounds and sequestering them in slag, and is therefore used for deoxidizing, and sometimes for desulfurization and denitrogenation.