Ferroalloys
Ferroalloys are alloyed metals that combine a high percentage of iron with a smaller percentage of other elements, enhancing the strength and properties of iron for various applications. They are crucial in the iron and steel industry, where they are used to produce stainless steel, high-strength steels, tool steels, and cast irons. The main ferroalloys include ferrochrome, ferromanganese, silicomanganese, ferronickel, ferromolybdenum, ferrotitanium, and ferrovanadium, each contributing unique traits to the metals they are mixed with. Major producers of ferroalloys are concentrated in countries like China, South Africa, Ukraine, Russia, and Kazakhstan, which collectively account for over 74% of global production.
Ferroalloys play a significant role beyond steelmaking; they are used in manufacturing catalysts, electrodes, and coatings, as well as in aerospace, medical implants, and household batteries. Their production primarily occurs in electric arc furnaces, where the melting point of ferroalloys is lower than that of the pure elements, facilitating their incorporation into molten metal. The evolution of ferroalloy usage has been driven by the increasing demand for durable and corrosion-resistant materials, especially in the context of modern advancements and economic growth in countries like China and India, highlighting their importance in global industrial economies.
Ferroalloys
Where Found
Ferroalloy production occurs in many countries around the world, but the primary ferroalloy-producing countries are China, South Africa, Ukraine, Russia, and Kazakhstan. These five countries produce more than 74 percent of the world’s ferroalloy supply. However, because the various ferroalloys contain a number of different elements, many parts of the world supply minerals important in ferroalloy production.
Primary Uses
Ferroalloys are used extensively in the iron and steel industry. The type of alloy produced depends upon the properties of the element that is added to the iron. Stainless steel, high-strength steels, tool steels, and cast irons are the major ferroalloy products. Some ferroalloys are also used to produce metal coatings, catalysts, electrodes, lighting filaments, aerospace and marine products, medical implants, and household batteries.
Technical Definition
Ferroalloys constitute a wide variety of alloyed metals that combine a large percentage of iron with a smaller percentage of one or more elements. Combining other elements with iron imparts superior strength to these alloys, and this increased strength enables the metals to be used in many important products within the metallurgical industry. Ferroalloys have lower melting points than do the pure elements that form them; therefore, they are incorporated more easily into molten metal. Manganese, chromium, magnesium, molybdenum, nickel, titanium, vanadium, silicon, cobalt, copper, boron, phosphorus, niobium, tungsten, aluminum, and zirconium are the primary elements mixed in varying proportions with iron to produce ferroalloys. Ferroalloys are produced primarily in electric arc furnaces; the nonferrous metal combines with the iron at high temperatures to produce the various types of steel.
Description, Distribution, and Forms
Much of thestainless-steel production of Europe, Asia, and North and South America is possible because of ferrochromium. In 2007, approximately 29 metric tons of stainless steel were produced throughout the world. Most chromite ore mining takes place in China, India, South Africa, Russia, Turkey, and Kazakhstan. The majority of chromite ore is smelted in electric arc furnaces to produce ferrochromium, which is then exported to the countries that manufacture stainless steel.
Ferromanganese and silicomanganese are primary ingredients in steelmaking. Most of the U.S. supply of these alloys is imported from South Africa, although China, Brazil, India, and Ukraine are also important producers. The United States also produces some ferromanganese at a plant near Marietta, Ohio. Besides being a key component in steel manufacturing, manganese is used in the production of household batteries. Silicomanganese production at plants in New Haven, West Virginia, the United Kingdom, and Ukraine has been vital to steelmaking for a number of years.
Ferrosilicon is a deoxidizing agent in cast iron and steel production. China, Brazil, and Russia are the main producers of ferrosilicon, with China producing more than four times as much as the other two countries.
More than 99 percent of ferronickel use within the United States is for stainless steel and heat-resistant steel. Stainless-steel cooking pots, pans, and kitchen sinks are products of the ferronickel industry. The United States does not produce any primary nickel but instead produces a remelt alloy with small percentages of chromium and nickel from recycled materials. Japan, New Caledonia, Colombia, Greece, Ukraine, Indonesia, the Dominican Republic, and Venezuela lead the world in ferronickel production.
Another major ferroalloy is ferromolybdenum, a component of stainless steels, tool steels, and cast iron. About 80 percent of world production of ferromolybdenum takes place in Chile, China, and the United States, while the remainder occurs in Canada, Mexico, and Peru.
Ferrotitanium plays a large role in the steel industry as a deoxidizing and stabilizing agent as well as an alloy that assists in controlling the grain size of steel. Titanium is not naturally found in metallic form but instead is mined from titanates, oxides, and silicotitanites. Ferrotitanium is then produced by an induction melting process. Steels with a high titanium content include stainless, high-strength, and interstitial-free (space-free) forms. Other important ferrotitanium uses include catalysts, pigments, floor coverings, roofing material, aerospace products, medical implants, armor, and marine industrial goods. Major producers of ferrotitanium include China, India, Japan, Russia, the United Kingdom, and the United States.
Ferrovanadium, used in the manufacture of catalysts and chemicals, is produced in the United States mostly from petroleum ash and residues as well as from tar sands. China and South Africa contribute 71 percent of the world’s supply of ferrovanadium, while Russia makes up most of the remaining supply.
History
Steel has been produced by a number of methods since before the fifteenth century, but only since the seventeenth century has it been produced efficiently. The Bessemer process, invented in the mid-1800’s by Sir Henry Bessemer, enabled steel to be mass-produced in a cost-effective manner. Improvements on the Bessemer process included the Thomas-Gilchrist process and the Siemens-Martin process of open-hearth steel manufacture. Basic oxygen steelmaking, also known as the Linz-Donawitz process, was developed in the 1950’s, and although the Bessemer process and other processes continued to be used for a few more years, basic oxygen steelmaking soon became the process of choice for modern steel manufacture.
Creating Ferroalloys
Ferroalloys have been used in the steel manufacturing industry primarily since the 1960’s. In the twentieth century, metallurgists discovered that adding varying amounts of manganese, silicon, or aluminum to the molten steel pulled oxygen away from the melted material, thus allowing for sound castings without bubbles or blowholes. The other ferroalloys—those containing chromium, tungsten, molybdenum, vanadium, titanium, and boron—provide a method for making specialty steels other than ordinary carbon steel. By adding small amounts of the other metals, high-strength, heat-resistant steels, such as stainless steel, can be produced.
The amount of steel that a country produces is often considered to be an important indicator of economic progress. Therefore, the production of ferroalloys within the iron and steel manufacturing industry is also a key factor of the economy of the countries in which it takes place. In the twenty-first century, the economic booms in China and India brought about a large increase in demand for steel products and a corresponding need for a large number of workers in this industry. The top producers of steel in the world are, in order of metric-ton production per year, China, Japan, Russia, and the United States. Each of these countries has many thousands of workers in its steel industry and in the mining industries, which supply the raw materials for iron and steel production.
Uses of Ferroalloys
The primary use of ferroalloys is in the manufacturing of iron and steel. Combining various metallic elements with iron results in a strong, stable product vital to many industries. Stainless and heat-resisting steels are produced from ferrochromium, ferrotitanium, and ferronickel. Ordinary carbon steel rusts, but stainless steel resists corrosion because of the chromium oxide film it contains. In general, at least 11 percent chromium must be added to the steel in order to produce the stainless quality. Up to 26 percent chromium must be added if the stainless steel is to be exposed to harsh environmental conditions. Although stainless steel has a huge number of applications in modern society, it is mostly used for cutlery, appliances, surgical instruments, cooking equipment, and aerospace parts. Because stainless steel is also resistant to bacterial growth, it is important in the cooking and medical industries. Stainless steel is also used in jewelry and firearm production.
Ferrochromium is used in the chemical industry as a surface treatment coating for metals. Besides the primary uses of ferroalloys in steelmaking, these substances are also used to produce catalysts in catalytic converters, pigments in paint, grinding and cutting tools, lighting filaments, and electrodes. Ferrosilicon is used by the military to produce hydrogen for balloons in a process that combines sodium hydroxide, ferrosilicon, and water.
Bibliography
Corathers, Lisa A. “Manganese.” USGS Minerals Yearbook (2007).
Dunkley, J. J., and D. Norval. “Atomisation of Ferroalloys.” In Industrial Minerals and Rocks, edited by Jessica Elzea Kogel. 6th ed. Littleton, Colo.: Society of Mining, Metallurgy, and Exploration, 2004.
Jones, Andrew. “The Market and Cost Environments for Bulk Ferroalloys.” In International Conference on Innovations in the Ferroalloy Industry. New Delhi: The Indian Ferro Alloy Producers’ Association, 2004.
Papp, J. F. “Chromite.” In Industrial Minerals and Rocks, edited by Jessica Elzea Kogel. 6th ed. Littleton, Colo.: Society of Mining, Metallurgy, and Exploration, 2004.
U.S. Geological Survey.