Developments in technology of steel making process
It
can be summarized that the steel production technology has followed an
evolutionary transition from the ovens used:
Pig
iron, which is refined to produce steel, is obtained. High modern ovens operate
in combination ovens basic oxygen furnaces and sometimes open oldest, as part
of a single steel plant pot. In these plants, the steel furnaces are loaded
with pig iron. The molten metal from various furnaces may be mixed in large
spoon steel before converting in order to minimize the effect of any
irregularities of the furnaces.
Operate
at high temperatures due to the regenerative preheating of the gaseous fuel and
air used for combustion. In the regenerative preheating the gases escaping from
the furnace are passed through a series of chambers filled with bricks, which
yield most of its heat. Then flow through the oven is inverted and the fuel and
air pass through the chambers and are heated by the bricks. From the chemical
point of view, is reduced by the carbon oxidation of the charge, and removing
impurities such as silicon, phosphorus, manganese, and sulfur, combined with
limestone and slag formed. These reactions take place while the metal of the
furnace is the melting temperature, and the furnace is maintained between 1550
and 1650 ° C for several hours until the molten metal having the desired carbon
content. When the carbon content of the cast reaches the desired level, the
furnace is tapped through a hole located in the rear. The molten steel flows
through a short channel into a large bucket located at ground level, below the
oven. Steel from the ladle is poured into molds to form ingots cast iron.
Recently they have implemented methods to process steel continuously without
having to go through the process of making ingots.
It
uses an oven tall pear shaped; I could lean sideways for loading and dumping.
By passing large amounts of air through the molten metal, atmospheric oxygen is
chemically combined with the impurities and removed. In the basic oxygen
process, steel is also refined in a furnace pear shaped tilt able laterally.
However, the air is replaced by a stream of nearly pure oxygen at high
pressure. When the oven is loaded and set upright, is lowered inside lance
oxygen. Below are injected into the furnace thousand cubic meters of oxygen at
supersonic speeds. The oxygen combines with the carbon and other unwanted
elements and initiates reaction stirring rapidly burning cast iron impurities
and transforms it into steel.
Electric
Arc Furnaces (1902) some heat furnaces for smelting and refining steel come
from electricity rather than burning gas. As conditions of refining these
furnaces can be regulated more strictly than furnaces open-hearth or basic
oxygen furnaces, electric furnaces are especially useful for producing
stainless steel and alloy steel to be manufactured to a specification very
demanding. Refined occurs in a sealed chamber, where the temperature and other
conditions are rigorously controlled by automatic devices. In the early stages
of the refining process high purity oxygen is injected through a lance, which
increases the temperature of the furnace and reduces the time required to
produce the steel. The amount of oxygen entering the furnace can be precisely
regulated at all times, preventing unwanted reactions of oxidation.
Process
of making steel with Electric Arc Furnace
Steelmaking
electric furnace is based on the melting of scrap by means of an electric
current, and the subsequent refining of the molten bath. The electric furnace
is a cylindrical vessel of large plate (15 to 30 mm thick) lined with
refractory material forming the hearth and houses the liquid steel bath and
slag. The remainder of the furnace is formed of water cooled panels. The vault
is movable to allow loading of the scrap through suitable baskets. The dome is
provided with a series of holes through which the electrodes, usually three,
which are thick graphite rods up to 700 mm diameter, are introduced. The
electrodes are displaced so that their distance can be adjusted to the load as
they are consumed. The electrodes are connected to a transformer that provides
a voltage conditions and adequate to blow the bow, with varying intensity,
depending on the phase of operation of the furnace intensity. Another hole in
the dome allows capturing the exhaust gases, which are conveniently purified to
avoid polluting the atmosphere. The furnace is mounted on a rocker pivoted
structure which allows it to proceed to the slag tapping and draining the bath.
Phases
of the manufacturing process
Melt
phase: once the scrap in the furnace and the reagents and slag forming agents
(mainly lime) dome moves to close the furnace and electrodes to the appropriate
distance down, making the jump arc to melt the materials fully loaded. The
process is repeated until the capacity of the furnace, this steel constituting
one line.
Refining
step: the refining is carried out in two stages. In the first refining of the
molten bath composition analyzes and proceeds to the removal of impurities and
undesirable elements (silicon, manganese, phosphorus, etc.) And perform a first
adjustment of the chemical composition by adding ferroalloys containing the
elements (chromium, nickel, molybdenum, vanadium or titanium). The obtained
steel is poured into a ladle, refractory lined, making Cuba the role of a
second refining furnace at the ends to adjust the steel composition and given the
right temperature for the next phase in the manufacturing process.
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