Manganese

Topic: Mineral Resources of India: Distribution and Conservation · NCERT: Class 10, Ch 5 "Minerals and Energy Resources"; Class 12, Ch 5 "Mineral and Energy Resources"

Meaning

Manganese is a hard, brittle, silvery-grey ferrous mineral (a mineral used mainly to make iron and steel). It is used to smelt iron ore and to make ferro-manganese, an alloy added to steel [2]. It matters because India cannot make steel without it. India has large reserves, but most of its ore is low grade, so it still imports more than it mines [2].

Explanation

What manganese does in steel

• Main use is steel. Across the world, 90–95% of the manganese ore mined goes into iron and steel [2].
• It is used to smelt iron ore (heat the ore in a furnace until the metal melts out).
• It is used to make ferro-manganese, an alloy of iron and manganese that is added to molten steel.

• About 10 kg of manganese is needed to make one tonne of steel [2].

• What it does inside steel [2]:

• It makes steel stronger, tougher, harder and easier to work.
• It is a deoxidiser (it removes oxygen) and a desulphuriser (it removes sulphur).

• It stops air holes ("blowholes") from forming in steel blocks.

• Other uses: bleaching powder, insecticides, paints and dry-cell batteries. Battery-grade ore must have at least 70% MnO₂ and at most 6% iron [2].

Main ores

• In nature, manganese is always found mixed with iron, laterite and other minerals [2].

Ore	Approx. Mn content [2]
Pyrolusite (MnO₂)	~63.2%
Psilomelane (manganese oxide with water and impurities)	45–60%
Manganite	~62.4%
Braunite	~62% (with ~10% silica)

Geology: which rocks hold it

• Manganese is found in almost all rock formations, but mainly in the Dharwar system. These are very old metamorphic rocks (rocks changed by heat and pressure) that are rich in metals [2].
• How the deposits formed: most Indian deposits are metamorphosed bedded sedimentary deposits [2].
• Cause: layers of sediment rich in manganese were laid down long ago.
• Process: later, heat and pressure changed these layers.

• Result: ore beds formed inside Archaean rocks (the oldest rock age).

• Two Archaean series [2]:

• Gondite Series: Madhya Pradesh (Balaghat, Chhindwara, Jhabua), Maharashtra (Bhandara, Nagpur), Gujarat (Panchmahal), Odisha (Sundargarh).

• Kodurite Series: Odisha (Ganjam, Koraput), Andhra Pradesh (Srikakulam, Visakhapatnam).

• Depth of deposits [2]:

• Shallow and lateritoid (laterite-like) in Odisha, Karnataka and Goa.
• Deep and regular in Madhya Pradesh, Maharashtra and Andhra Pradesh.

Reserves, grade and production

• Total reserves/resources (as on 1.4.2020): 503.62 million tonnes. Of this, 75.04 Mt are "Reserves" (proven and ready to mine) and 428.58 Mt are "Remaining Resources" [2].
• Grade problem [2]:
• Only 8% of resources are ferromanganese grade.
• Only 0.16 Mt are battery/chemical grade.

• 69% of ore produced in 2021-22 was low grade (below 35% Mn). Only 8% was high grade (above 46% Mn).

• Production 2021-22: 2,696 thousand tonnes, from 127 reporting mines. 32 public-sector mines gave 46% of output [2].

Where it occurs

In India: reserves and production by state

State	Share of reserves (1.4.2020) [2]	Share of production (2021-22) [2]
Odisha	34% (1st)	19% (3rd)
Karnataka	24% (2nd)	—
Madhya Pradesh	12%	31.5% (1st)
Maharashtra	12%	27% (2nd)
Goa	7%	—
Andhra Pradesh	6%	—
Jharkhand	3%	—

Producing belts

• Madhya Pradesh: the Balaghat–Chhindwara–Nimar–Mandla–Jhabua belt. It has Gondite deposits and lies far from steel plants. The state is exploring for new manganese in Jabalpur, Balaghat, Chhindwara and Jhabua [2].
• Odisha: Bonai, Kendujhar, Sundergarh, Gangpur, Koraput, Kalahandi, Bolangir. It lies in the central part of the iron ore belt, close to steel plants.
• Karnataka: Dharwar, Ballari, Belagavi, North Canara, Chikkamagaluru, Shivamogga, Chitradurga, Tumakuru.
• Maharashtra: Nagpur, Bhandara, Ratnagiri. It is far from steel plants.
• Minor producers: Telangana, Goa, Jharkhand.

MOIL Ltd: the main public-sector producer

• Headquarters at Nagpur. It is India's largest manganese ore producer [2].
• Its mines are in Nagpur and Bhandara (Maharashtra) and Balaghat (Madhya Pradesh). All are about a century old [2].
• Balaghat mine is the largest. It is about 435 m deep, and a shaft is being sunk to 750 m. Ore goes to the railheads by aerial ropeways [2].
• Dongri Buzurg mine (Bhandara) is opencast. It produces manganese dioxide ore for dry batteries [2].
• MOIL runs a 12,000 tonnes-per-year ferromanganese plant at Balaghat. Its target is 3.5 Mt of ore by 2030 [2].

In the world

• Reserves: about 1,700 Mt of metal content. South Africa 38%; China, Australia and Brazil 16% each; Ukraine 8%; Gabon 3%; India 2% [2].
• Production 2021: about 56 Mt. South Africa 34%, Gabon 16%, China 12%, Australia 11%, Ghana 6%, India 4% [2].
• Imports into India 2021-22: 6.50 Mt, up 60% from 4.05 Mt. Sources: South Africa 44%, Gabon 21%, UAE 10%, Australia 8% [2].
• Future source: deep-sea polymetallic nodules (small manganese-rich lumps on the ocean floor) [2].

Don't confuse with

• Chromite: also a ferrous steel-alloy mineral, but more than 96% of India's resources are in Odisha (Sukinda and Baula–Nuasahi belts), and it is used for stainless steel and refractories [3]. Manganese is spread over many states, and Madhya Pradesh leads its output.
• Reserves vs production: Odisha leads manganese reserves (34%). Madhya Pradesh leads production (31.5%) [2].
• Gondite vs Kodurite Series: Gondite goes with Balaghat, Chhindwara and Bhandara. Kodurite goes with Ganjam, Koraput and Srikakulam [2].
• Critical minerals (2023): manganese is not on India's list of 30 critical minerals, even though it is vital for steel [4].

Prelims Hooks

• Order of manganese producers in 2021-22: Madhya Pradesh > Maharashtra > Odisha [2].
• Odisha (34%) is 1st in manganese reserves, and Karnataka (24%) is 2nd [2].
• Pyrolusite (MnO₂) is the main manganese ore. Dongri Buzurg (Bhandara) supplies MnO₂ ore for dry batteries [2].
• MOIL has its headquarters in Nagpur. Its largest mine is Balaghat (Madhya Pradesh) [2].
• About 10 kg of manganese is used per tonne of steel. 90–95% of world manganese ore goes into iron and steel [2].
• South Africa leads the world in both reserves (38%) and production (34%). India has just 2% of reserves and 4% of output [2].

Mains Points

• Location mismatch raises costs (GS-I distribution):
• Odisha's manganese lies inside the iron ore belt, close to steel plants.
• The century-old Gondite mines of Madhya Pradesh and Maharashtra are far from the steel plants of the Chhota Nagpur–Odisha belt, so moving the ore costs more.

• So the biggest reserves (Odisha) and the biggest output (Madhya Pradesh) are in different places.

• Import dependence despite large reserves (GS-III resources):

• 69% of ore produced is low grade, and only 8% of resources are ferromanganese grade [2].
• Steel output keeps growing, so India imported 6.50 Mt in 2021-22, more than double its own output of 2.7 Mt [2].

• Possible answers: beneficiation (processing low-grade ore to raise its metal content), deeper mechanised mining (MOIL's 3.5 Mt target by 2030) and deep-sea polymetallic nodules [2].

• Worker health and sustainable mining (GS-III environment): long exposure to manganese dust can cause manganism, a nerve disorder with symptoms like Parkinson's disease [2]. This calls for dust control and health checks in old, deep mines such as Balaghat.

Related concepts

• Chromite

Read more

• Manganese and chromite