Manganese , with the symbol Mn, is a fragile metallic element with a silvery-white appearance. It is used mainly in alloys. Manganese is one of the transition elements of the periodic system . Its atomic number is 25.
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- 1 History
- 2 Main features
- 3 Applications
- 4 Abundance and obtaining
- 1 Main deposits in Cuba
- 5 Precautions
- 6 Biological role
- 7 Nutrition
- 1 Foods where we find manganese
- 2 Benefits of manganese for our body
- 3 Symptoms of manganese deficiency
- 8 Uses in medicine
- 9 Sources
Manganese dioxide , MnO2, has been found in cave paintings (giving a black color). Manganese compounds have also been used throughout history, for example by the Egyptians and Romans, to discolor or color glass . Manganese has also been found in the iron mines used by the Spartans, and it is thought that perhaps this is due to the special hardness of their steels.
In the 17th century , the German chemist Glauber first produced permanganate, a widely used laboratory reagent. In the mid- 18th century , manganese dioxide was used for the production of chlorine . The Swedish chemist Scheele was the first to discover that manganese was an element, but it was Johan Gottlieb Gahn who isolated it by reduction of carbon dioxide.
In the early 19th century , manganese began to be tested in steel alloys . In 1816 it was found that it hardened steel, without making it more brittle.
Manganese is a grayish-white transition metal , similar to iron . It is a hard and very fragile metal, refractory and easily oxidized. Manganese metal can be ferromagnetic, but only after special treatment.
Its most common oxidation states are 2+, 3+, 4+, 6+, and 7+, although compounds with all oxidation numbers from 1+ to 7+ have been found; compounds in which manganese has a 7+ oxidation state are very strong oxidizing agents . Within biological systems, the Mn2 + cation frequently competes with Mg2 +. It is used mainly alloyed with iron in steels and other alloys.
The chemical composition of manganese ore determines its different industrial uses.
Manganese constitutes one of the most necessary strategic minerals , used in the iron and steel industry , in the manufacture of dry batteries , and in chemical uses, in the production of steel, ferro-manganese alloys and as a purifying agent, since its great greed for oxygen and sulfur , it is used to rid the iron ore of these impurities, decolorizing the glass, obtaining manganese salts, among others.
Non-ferrous manganese alloys include manganese bronze (composed of manganese, copper , tin and zinc ), resistant to corrosion from seawater and used in the manufacture of ship propellers and torpedoes , and manganin (composed of manganese, copper and nickel ), used in the form of cables for high precision electrical measurements, since its electrical conductivity hardly varies with temperature.
Manganese dioxide (MnO2) occurs in nature in the form of pyrolusite, and can be obtained artificially by heating manganese nitrate. It is used in paints and varnishes, to paint glass and ceramics , to obtain chlorine and iodine and as a depolarizer in dry cell batteries. The manganese sulfate (II) (MnSO4), a crystalline pink solid, is prepared by the action of sulfuric acid on manganese dioxide, and dyes used for cotton . The sodium permanganate and the potassium (NaMnO4 and KMnO4) are dark purple crystals, formed by the oxidation of manganese acid salts, and are used as oxidants and disinfectants.
Abundance and obtaining
Manganese comes from Pyrolusite, which comes from the Greek pyrós, fire and lysis, decomposition.
Pure manganese is obtained by combustion of pyrolusite (manganese dioxide) with aluminum powder, or by the electrolysis of manganese sulfate. This metal does not occur in nature in its pure state, except in meteorites, but it is widely distributed throughout the world in the form of ores. such as rhodochrosite, franklinite, psilomelana and manganite. It ranks 12th in abundance among the elements of the earth’s crust. Due to its great affinity for oxygen, it generally occurs in the form of oxides and also in silicates and carbonates. The ore of this mineral most used in the industry is Pyrolusite (MnO2), 63% manganese, but others are used such as braunite (MnS12O3) of 69%, rhodonite (MnSiO3), rhodochrosite(MnCO3), hübnerite (MnWO4) etc. It has also been found in marine nodules , where the manganese content ranges between 15 and 30%, and where it would be possible to extract it. Manganese-producing countries include Ukraine , Georgia , South Africa , Brazil , Bolivia , China, and Mexico .
Main deposits in Cuba
The most important deposits of pyrolusite are in the East, with Ponupo, near El Cristo, occupying the first place. In the Ponupo mines, the mineral is found by a process that is based on the different densities between the mineral and the gangue, which causes particles of the same volume to fall with speeds in a fluid medium such as water . With this method, it is achieved that the concentration of the mineral reaches a value of not less than 36% of manganese, which is necessary for it to be subjected to pelletization, an operation that is verified in Felton.
- Manganese is an essential element, being necessary a contribution of between 1 to 5 mg per day, an amount that is achieved through food.
- Manganese in excess is toxic. Prolonged exposures to manganese compounds, inhaled or oral, can cause adverse effects on the nervous , respiratory, and other systems.
- The potassium permanganate , KMnO4, is corrosive.