Adverse Effects of 9 Elements in Iron Ore on Its Smelting
2025/2/14 14:53:58 Other22045
Usually, there are
two smelting types of iron ore:
1. Acid sinter
It mainly
consists of iron concentrates and rich iron powder mixing with agents of fusion.
The iron ore contained are mainly magnetite and hematite, and main binding
minerals are fayalite (2FeO?SiO
2) and kirschsteinite (CaO?FeO?SiO
2).
The sintered acid
iron ore does not pulverize naturally during the cooling process. It has high
mechanical strength, and contains much ferric oxide (FeO), resulting in poor reducibility
and bad temperature resistance.
A large amount of
limestone is required to smelting this kind of iron ore and concentrates.
2. Iron ore concentrates
Poor
iron ore can be ground and separated to obtain an iron powder with high grade. Crusher is the raw material to produce artificial rich iron ore.
Iron
ore concentrate can be divided into magnetic concentrate, hematite concentrate,
and limonite concentrate according to different iron ore components. It can
also be divided into weakly magnetic concentrate, strongly magnetic concentrate,
flotation concentrate, and gravity concentrate.
In general, magnetite concentrate is obtained from magnetic ores by the method
of magnetic separation.
Hematite concentrate is obtained by gravity separation, flotation
separation, high-intensity magnetic separation, and magnetizing
calcination ¨C
magnetic separation or a combined separation process.
Limonite concentrate is obtained by gravity separation, high-intensity
magnetic separation, or magnetizing calcination ¨C magnetic separation.
There are 4
details of iron concentrates required by smelting plant:
High iron content
The iron content of
magnetite concentrate should be more than 65%, iron in hematite concentrate
should be more than 60£¥ and in limonite concentrate
should be more than 50%. The fluctuation of iron content should be in the range
of 0.5%.
Low water content
The humidity
contained in the concentrate has large effects on storage, transportation,
mixture, and briquette. Commonly, the humidity of magnetite concentrate should
be no more than 10%, and no more than 12% in limonite concentrate and hematite
concentrate.
Uniform size
The iron
concentrate used for producing pellets should be uniform. There should be more
than 70% of particles under the size of 0.074 mm, and the specific surface area
should be better to be in the range of 1200 to 2000 cm2/g.
Low impurities
The fewer impurities
(such as sulfur, phosphorus, lead, arsenic, zinc and copper), the better iron
concentrates. It is usually required:
9 elements in iron ore badly effected on
its smelting
The minerals badly effected
on the iron ore smelting are usually sulfur, phosphorus, potassium, sodium,
lead, arsenic, zinc, titanium and copper. Generally, they have the following
bad effects on smelting:
Elements that bad for iron ore smelting
Sulfur (S): it is the most harmful
element to iron ore smelting. It will make the steel with hot brittleness. More
sulfur contained in iron ore, more cost in the following blast furnace
desulfurization will spend.
Phosphorus (P): it is also the
common harmful element for steel material. It will bring the steel with cold
brittleness. Phosphorus in iron ore will be sintered into the cast iron during
the smelting process.
Alkali metals (K & Na): alkali metals
mainly include potassium and sodium.
Lead (Pb): almost all lead is
reduced in the blast furnace. As the density of lead is as high as 11.34 t/m3,
which is easy to destroy and burn though the brick joints of the furnace
bottom.
Zinc (Zn): zinc is easy to gasify,
and the vaporized zinc vapor easily enters the brick joint. The zinc will
become zinc oxide after oxidation, and its volume will expand, thereby
destroying the refractory brick lining on the upper body of the furnace, and harming
the smelting effect.
Arsenic (As): arsenic is also one of
the harmful elements for steel, which makes the steel cold brittleness and poor
welding performance.
Copper (Cu): copper will bring the
steel with hot brittleness, which will make steel hard to roll and welding. However,
a small amount of copper can improve the corrosion resistance of steel.
Titanium (Ti): it can improve the
wear resistance and corrosion resistance of steel.
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