Manganese: Element Properties And Uses

Manganese is an essential chemical element widely used across industries, from steel production and battery manufacturing to chemical processing. It also significantly impacts human health. Its versatility makes it one of the most important elements in various industrial and biological processes.

Introduction to Manganese

Manganese is an important transition metal of the periodic table, with the atomic number 25 and symbol Mn. It is one of the most common elements in nature, which may be found in a free state in pyrolusite and rhodochrosite ores. Despite the relative abundance of manganese, it is hardly ever found in its pure state and is usually combined with other minerals. This is where manganese finds the greatest use as an alloying agent to increase hardness, strength, and resistance of steel to corrosion. It is a trace element necessary for higher organisms, including humans, due to its role in many metabolic processes.

Manganese is widely utilised in different industries, but it plays a more vital role beyond the limits of industries and manufacturing processes—within the biological functions of the human body. From batteries to bone and brain health, manganese is indispensable.

Chemical Properties

Manganese is a highly reactive metal, especially when it comes into contact with air and moisture. The reactivity of the metal is due to its unique property to have multiple oxidation states, ranging from +2 to +7, with the most common oxidation states being +2 and +4.

This property of having multiple oxidation states makes it an essential metal for use as a catalyst during various chemical reactions. For instance, it is regularly used as a catalyst in various industrial reactions because of its property to change its oxidation states.

One of the most prominent characteristics of manganese is that it is able to form manganese oxides, which are widely applied in pigment production and catalysis. By reacting manganese with chlorine, manganese chloride (MnCl₂) is formed; this is widely applied in various chemical reactions. Manganese is highly soluble in acids, with hydrochloric acid being most favoured; thus, manganese salts such as manganese sulfate (MnSO₄), applied in agriculture and battery production, are formed.

Physical Properties

Manganese is a hard, brittle metal that has a silvery-grey appearance. Some of its key physical properties include:

• Density: 7.43 g/cm³
• Melting Point: 1,244°C (2,271°F)
• Boiling Point: 2,095°C (3,803°F)
• Electronegativity: 1.55 (Pauling scale)
• Hardness: 6 on the Mohs scale
• Crystal Structure: Cubic

These properties make manganese suitable for high-temperature applications, especially in steel production, where its high melting point benefits strength under extreme heat.

Applications of Manganese

1. Steel Production

Manganese is used as a steel alloy. Manganese acts as an alloying agent that increases the hardness and strength of steel. Manganese eliminates impurities such as sulfur and oxygen from steel. Manganese forms a crucial component of high strength steel. Special steels such as stainless steel and high carbon steel also incorporate manganese as an alloying component that improves its strength and composition. Manganese is widely used as a micro-element that adds strength to special steels.

2. Battery Manufacturing

Manganese plays a significant role in the manufacture of dry cell batteries, including alkaline batteries and lithium-ion batteries. Manganese dioxide (MnO₂) is applied in alkaline batteries as a cathode component; thus, it has a significant relationship with the ability to store energy. In a lithium-ion battery, manganese is utilised as a stabilisation agent. Manganese cathode materials, for instance, lithium manganese oxide (LiMn₂O₄), have numerous applications in electric vehicles and various devices.

3. Fertiliser

Manganese is a trace element essential for plants and participates in the process of photosynthesis. It is often used to fortify fertilisers, especially those intended for plants that require a higher dose of manganese. This includes rice, corn, and wheat. In this respect, manganese is significant as it enhances crop development.

4.  Pigments and Catalysts

Manganese compounds are also used extensively as pigment materials in ceramics, glass, and paints. Manganese violet and cobalt-manganese pigments are some of the compounds that give coloured appearances to glass and ceramics. Manganese is also known to be a catalyst and is widely used as such in certain chemical reactions, such as fuel synthesis and wastewater treatment. Potassium permanganate (KMnO4), a chemical comprising manganese, is used as an oxidising agent.

5. Water Treatment

Manganese, particularly in its form as potassium permanganate, serves as a water treatment agent. This is due to its ability to oxidise certain water contaminants such as iron, hydrogen sulfide, and manganese. Therefore, manganese can be considered a very significant element for water purification.

Manganese and Human Health

Manganese represents an important trace element for human health. It is involved in the activity of various enzymes that facilitate bone formation, amino acid metabolism, and cholesterol synthesis. In addition to these functions, manganese exerts antioxidant activity and thus contributes to cell protection from the action of free radicals.

However, while manganese is essential for health, exposure to excessively high levels, particularly through inhalation in dust and fumes resulting from industrial processes, can be highly toxic. Long-term exposure to high concentrations of manganese has been associated with neurological disorders such as manganism, which resembles Parkinson's disease. Symptoms of manganism include tremors, difficulty walking, and cognitive impairment. Proper handling and workplace safety are thus important in various industries that depend heavily on manganese.

Current Extraction and Production 

Manganese is generally processed from its compounds using two major processes:

• Hydrometallurgical Process: This process entails the use of a series of reactions to dissolve the ores using an acid solution. The resulting solution undergoes treatment to produce pure manganese.
• Pyrometallurgical Process: Manganese ores are melted at very high temperatures along with carbon to remove manganese oxide and yield pure manganese.

Similar Industrial Products

Manganese is involved in the production of essential industrial materials:

• Steel Alloys: Stainless steels and high-strength steels, utilised in the construction, automotive, and heavy machinery industries, have an immense demand for manganese as alloying elements to enhance performance.
• Batteries: Manganese dioxide is a major component in dry batteries and is a critical material for lithium-ion batteries needed for electric vehicles and consumer electronics.
• Fertilisers: Manganese is a trace element in fertilisers, which serves as nutrients to facilitate effective nutrient uptake in plants.

FAQs

1. What is the primary use of manganese?
   Manganese is primarily used in steel production as an alloying agent to enhance the strength, hardness, and resistance to corrosion of steel.
2. Is manganese toxic to humans?
   While manganese is essential in small amounts for human health, excessive exposure to manganese, particularly as dust or fumes, can be toxic and lead to neurological disorders.
3. How is manganese extracted from its ores?
   Manganese is extracted through hydrometallurgical processes (using acid to dissolve ores) or pyrometallurgical processes (smelting ores at high temperatures).
4. What are the most common manganese compounds?
   The most common manganese compounds include manganese sulfate (MnSO₄), manganese dioxide (MnO₂), and potassium permanganate (KMnO₄).
5. What industries use manganese?
   Manganese is essential in steel production, battery manufacturing, agriculture (fertilisers), and water treatment.