From Blast Furnace to Arc Furnace: The Dual Processes of Ferromanganese Manufacturing
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| Ferro Manganese |
Ferromanganese or ferroalloy manganese is an alloy of iron and manganese, generally containing between 15% and 90% manganese. Ferromanganese is used as a deoxidizer for molten metals like steel and cast iron. Very small amounts of ferromanganese are used to remove dissolved oxygen, sulfur, and phosphorus from the liquid metal before and during the production of steel and cast iron. Major world producers of ferromanganese include South Africa, Ukraine, India, Australia and Brazil.
What is Ferromanganese?
Ferromanganese, also known as ferromanganese alloy or manganese iron alloy, is a
ferroalloy which is produced by reducing manganese oxide ore in a blast furnace
or submerged arc furnace. Ferromanganese consists of 65-80% manganese and the
remaining percentage being iron. The manganese content in ferromanganese can
vary between 15–90%. The alloy is produced as a hard nodular agglomerate of
manganese-iron intermetallic compounds. Ferromanganese is one of the principal
alloying elements used in the production of various types of steels because of
the role it plays in removing detrimental interstitial elements like oxygen,
sulfur and phosphorus from liquid steel.
Production of Ferromanganese
There are two main production methods for manufacturing Ferro
Manganese - blast furnace
process and submerged arc furnace process. In the blast furnace process, a
mixture of manganese ore, coke and limestone is charged into a blast furnace
from the top and preheated air is blown into the furnace from tuyeres at the
bottom. The ore undergoes continuous reduction at high temperatures caused by
combustion of coke. The manganese-iron alloy gets collected at the bottom of
the furnace as molten ferromanganese which is then poured into molds.
The submerged arc furnace process has become more popular as it is more energy
efficient than the blast furnace route. In this process, manganese ore, coke
breeze and fluxing agents like limestone are fed into an electric arc furnace
from the top. Powerful electric arcs are generated between the graphite
electrodes suspended above and the charge materials below which rapidly heats
and melts the raw materials. The molten ferromanganese produced is periodically
tapped from the bottom of the furnace.
Chemical Reactions in Ferromanganese Production
The key chemical reactions that take place during the production of ferromanganese
are:
- Reductive smelting of manganese oxide ore: Mn3O4 + 4C → 3Mn + 4CO
- Reduction of iron oxide impurities in ore: Fe3O4 + 4C → 3Fe + 4CO
- Carburization reaction between manganese/iron and carbon: Mnx/Fex + yC →
Mnx/Fey + yCO
- Side reactions between manganese/iron and other elements like sulfur and
phosphorus from impurities.
These redox reactions occur at temperatures between 1,200 to 1,500 °C in the
furnaces. Carbon monoxide formed as a byproduct diffuses out of the furnaces
while molten ferromanganese accumulates at the bottom. The final alloy obtained
typically contains 65-80% manganese depending on the process conditions.
Uses of Ferromanganese
Some key uses of ferromanganese alloy include:
- Deoxidizer in steelmaking: Very small amounts of ferromanganese (0.1-1%) are
added to liquid steel or cast iron to remove residual dissolved oxygen from the
melt. Manganese has strong affinity for oxygen.
- Alloying addition: Ferromanganese addition enhance strength, hardness and
wear resistance in steel during casting and rolling. Manganese is a
substitutional alloying element which strengthens steel.
- Desulfurization: Manganese forms stable manganese sulfide inclusions with
sulfur, allowing its removal from liquid steel. This lowers sulfur content in
steel.
- Heat treatment: Manganese improves hardenability and impact resistance of
steels subjected to quenching and tempering heat treatment processes.
- Battery industry: Ferromanganese is used in production of steel for batteries
due to good corrosion resistance property of manganese.
- Welding rods: Ferromanganese is a key alloying ingredient in manufacturing of
shielded metal arc welding electrodes/wires.
With rising steel production globally, consumption of ferromanganese alloy has steadily
increased over the years to meet the stringent quality specifications demanded
in changing times. South Africa, India and Ukraine are some of the key
exporters of this ferroalloy.
Health and Safety Considerations
Workers handling ferromanganese alloy should take proper precautions as it can
pose health hazards if exposed to unsafe levels. Some important safety aspects
related to ferromanganese alloy are:
- Manganese dust/fumes inhalation can cause manganism or manganese poisoning
affecting central nervous system if exposed to high concentrations over long
periods. Proper ventilation and masks should be ensured.
- Skin contact with ferromanganese alloy may cause dermatitis. Appropriate
gloves and protective clothing must be worn.
- Solid lumps of ferromanganese alloy may cause burn injuries if contacted with
bare skin at high temperatures.
- Safety glasses must be used nearareas where ferromanganese particles could
fly off.
- Ferromanganese dust is combustible. Firefighting facilities and sprinklers
should be maintained.
- Good housekeeping and hygiene practice must be followed at production and
storage locations of ferromanganese. Regular health checkups of workers are
recommended.
- Spillages should be cleaned immediately as manganese is toxic to aquatic life
if enters water bodies. Approved disposal methods are to be followed.
Proper safety standards set by authorities need to be diligently complied with
to ensure safe handling of ferromanganese during manufacturing and
transportation.
Ferromanganese is an indispensable ferroalloy widely employed in steelmaking
for improving mechanical properties and purity of the metal. Though
ferromanganese production is energy intensive, industry is continuously
striving for enhanced process efficiencies and automation. With rapidly growing
requirements from steel, construction, automotive and related sectors, demand
for ferromanganese alloy is expected to keep rising globally. Simultaneously,
focus on minimizing the environmental footprint and adopting sustainable
practices in ferromanganese industry will also be crucial going
For
more Insights, Read –
https://www.newsstatix.com/ferro-manganese-size-share-analysis-growth/
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