Iron and manganese ore are important raw materials in steel and they are widely used in steel industry. The main sources of these two mineral resources are iron-manganese ore deposits. Iron-manganese ore deposits are widely distributed on earth, but the most important ones are located in Brazil, China, Russia and India.
Iron-manganese ore deposits are composed mainly of iron and manganese with minor amounts of other elements. They are mined mainly for their iron content, but other elements are also extracted from them. The ore usually contains a mixture of oxides, hydroxides and carbonates. The iron is found in magnetite, hematite and siderite while the manganese is found mainly in rhodochrosite, pyrolusite, and thenardite.
Mining of iron-manganese ore deposits are done either by open pit or by underground methods. Open pit mining is used when the ore is near the surface. The ore is quarried and transported to a processing plant for further beneficiation. The processed ore is then pelletized or sintered for blast furnace use or further refined into steel.
For underground mining, traditional techniques include gophering, tunneling, blasting, and in-situ leaching. Gophering involves excavating tunnels in the orebody in order to access the ore. Tunneling uses larger tunnels to gain access to orebodies and is a preferred method as it is less costly and less damaging to the environment. Blasting is used to loosen the ore so it can be extracted and is often used in combination with other mining techniques. In-situ leaching makes use of solutions to extract minerals from the orebody without physically mining it. This can be done through in-situ leaching of ore with a solution or by the addition of acid to bring out the minerals.
The concentration of iron and manganese in orebodies vary from region to region and from deposit to deposit. The average grade of iron-manganese ore deposits is usually around 40% iron and 25% manganese, but some deposits in China and Brazil can have up to 70% iron and 30% manganese.
The processing of the ore to produce iron and manganese concentrates is a complex process which is usually done in combination with other beneficiation processes such as grinding, magnetic separation, flotation, and leaching. The concentrates are then further processed to produce pig iron or steels.
Overall, iron-manganese ore deposits are crucial resources for steel industry and are becoming increasingly important as demand for steel increases around the world. A truly sustainable mining industry needs access to reliable and affordable supplies of iron-manganese ore in order to meet the needs of the steel industry.
