5/25/2022
Crucible Process
Major Occurrences in the Crucible
Process
Naom Kerubo
Emmanuel Githinji
Austin Omondi
Hannevick Ongara
Reinhard Njuguna
Evance Mboya
EMAQ/2020
THE TECHNICAL UNIVERSITY OF KENYA
Crucible Process
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The Crucible Process
Introduction
In today's modern world, the technical industries make use of a variety of different
processes, including one known as the crucible process. Within the context of the processing
industry, the process entails the utilization of nontechnical procedures for the production of
substances. The vast majority of the processes that go into the production of steel and other hard
metals make use of the process in almost every stage of the manufacturing process. The use of
the process is associated with a great number of risks, and as a result, in addition to the
effectiveness and the simplicity with which the method can be implemented, there are a great
number of difficulties that need to be taken into consideration in the manner in which the method
is used in the business world. Because of this, the primary purpose of this paper is to investigate
the process that goes into the production of steel, as well as the difficulties that come up as a
result of applying the process in the various industries that make use of it. The safety measures
that are designed to protect users from being injured as a result of the process will make the
application and use of the process more efficient, and as a result, it is in everyone's best interest
to bring those measures to everyone's attention in this document. The paper also discusses the
drawbacks that are experienced by the industries as a result of the process, which is what causes
the crucible process to be an ineffective method of manufacturing or producing all of the metals
that are intended to be used in various parts as well as in the other industries. These drawbacks
are mentioned in the paper.
The process
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The crucible process is one of the more traditional methods for the production of steel. As
the name suggests, the process entails heating a source of iron and a source of still in a crucible
furnace at high temperatures that are higher than the point at which they will melt. Wrought iron
and cast iron are two examples of sources of iron, while charcoal is by far the most important
source of carbon in this process. This technique allows for the production of steel in three
distinct ways (Crucible Process | Metallurgy | Britannica, n.d.). [Crucible Process | Metallurgy |
Britannica] To begin, it could be made using the diffusion method or process, which is also
referred to as the wrought iron carburization method. To do this, charcoal is packed into a
crucible with wrought iron, and then the mixture is heated. During the heating process, the
carbon in this mixture will diffuse into the iron, which will result in the formation of steel, which
is simply an alloy of carbon and iron. Heating cast iron is the second step in the crucible process.
The goal of this step is to remove carbon from the iron, which will result in the production of
steel. The final strategy calls for heating wrought iron and cast iron together in a crucible before
combining the two. Cast iron is the material that serves as the source of carbon in this scenario.
Cast iron and wrought iron are the two varieties of iron that are combined into one another to
create steel. The crucibles that are utilized in this method are almost always constructed out of
fire clay.
The procedure consists of the following straightforward steps:
Within a crucible made of fire clay, fragments of wrought iron are combined with
charcoal. Wrought iron is merely a source of iron, whereas charcoal is a source of carbon due to
the fact that steel is an alloy composed of iron and steel.
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After that, the crucibles made of fire clay are heated using an appropriate method. It is
necessary for the source to be able to generate sufficient heat to melt whatever is contained
within the crucible. According to What Is Crucible Steel? (n.d.), the temperatures should
consequently reach approximately 16000 C. The most common types of fuel used to generate
heat are coke, oil, and gas. Coke was the primary source of heat and was used to heat the crucible
because the crucible process is an old method that has been used since the 17th century.
However, as time went on, coal ran out and became less profitable to use; this led to an increased
demand for an alternative source of heat that was superior and more suited to the environment.
Because of this, gas and oil were utilized as the primary heat sources.
As soon as that temperature is reached, carbon begins to diffuse into the molten iron,
which results in the formation of steel. The molten steel is then transferred, as shown in figure 1,
from the crucible into iron molds via a series of channels.
Figure 1(What Is Crucible Steel?, n.d.)
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It then cools and takes the shape of the mold used. A diagrammatic representation of the
crucible process is as follows.
Figure 2(Crucible Process | Metallurgy | Britannica, n.d.)
A number of things can be gleaned from the aforementioned figure 2. To begin, fuel gas
is utilized as a source of heat in this establishment. As was mentioned earlier, the use of coal as a
source of heat in the crucible process is declining in popularity, and fuel gas has taken its place
as the most effective alternative. The two valves' primary function is to regulate both the ratio of
air to fuel that is being burned and the volume of combustion air that is being drawn into the
furnace. In order to create steel through the crucible process, oxygen is needed to combust
carbon and then allow it to diffuse into molten iron. This is necessary for the formation of steel.
Through the charging doors, solid wrought iron and carbon are introduced into the crucible
(Crucible Steel - an Overview | ScienceDirect Topics, n.d.). Clay bricks are used extensively
throughout the construction of the regenerator chambers. This is due to the fact that they have
excellent resistance to heat and are able to withstand extremely high temperatures.
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Figure 3
Figure 3 shows a real and more traditional representation of the crucible process where
coal was used as the source of heat. It is also observed that the crucible does not have an outlet
channel. However, the supporting arms allow the crucible to rotate back and forth. Molten steel
is therefore collected by tilting the crucible and allowing the molten steel to flow out.
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Precautions in the Crucible Process
1.
In order to protect themselves from getting burns, all of the technicians are
required to wear protective gear at all times. This includes rubber gloves, safety boots,
and aprons.
2.
When working with molten metal or tapping the furnace in the crucible,
you should always protect your eyes by wearing goggles designed for that purpose.
3.
The crucible needs to be kept in an environment that is dry and at a
consistent temperature in order to avoid any damage and maintain its effectiveness over
time.
4.
It is important to inspect the crucibles on a regular basis for any cracks or
other defects in order to prevent the leakage of molten steel, which can result in burns to
technicians as well as damage to the surrounding environment.
5.
When working with the molten steel in the crucibles, it is important to use
the fixed tongs and shanks in the appropriate manner.
6.
Before beginning the process, the crucible should have any gases inside of
it driven out by blowing dry air into it before it is lit. This will help prevent any
explosions that could occur.
7.
It is important to avoid throwing damp or wet metal into the crucible while
it is still burning because this can cause a blast that will cause metal to splatter and fly
around, which is hazardous for the technician because it can cause burns or contaminate
the eye.
8.
The technicians are responsible for being aware of and adhering to all of
the safety precautions that are outlined in the manuals governing the manufacturing
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process. During the process of making crucibles, it is imperative that each step be carried
out in the appropriate manner.
Applications
The creation of high-quality tools has traditionally been the primary application of
crucible steel. The technique of melting steel in crucibles or pots was implemented as a means of
enhancing the quality of the end product produced by the cementation furnace.
In nonferrous metallurgy, the crucible process is used for producing alloys of nonferrous
metals and for melting metals and alloys in preparation for casting. Both of these tasks take place
in a crucible.
The constituents of crucible steel can be altered according to one's whims, allowing for
complete command over the final product and enabling the production of a wide variety of alloy
steels containing trace amounts of unusual constituents that could not be reliably produced using
the Bessemer or open-hearth processes.
The steel that is produced through the crucible process is reserved for use in the
manufacture of cutting tools and the highest quality cutlery.
Additionally, the refining of steel is the primary application of the crucible process. The
method eliminates impurities in the steel and iron scrap by melting it in the crucible, which
enables the production of steel of a higher quality than could be achieved through the use of any
other method.
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In addition to its use in the production of metal-cutting tools and wood-working tools,
crucible steel is also utilized in the production of piano wire and other high-quality wires, highly
tempered springs, armor-piercing projectiles, and other steel articles that require exceptional
purity or hardness.
Cast steel, also known as crucible cast steel, is another name for crucible steel. This is
due to the fact that crucible steel can be cast into a variety of shapes by pouring it from the
crucible into suitable molds, and that this technique can be utilized in the production of steel
castings.
Advantages of the Crucible Process
1. The Crucible process is affordable to a significant degree. This is due to the fact that it
first requires the melting of pig iron, which has a high carbon content but a low melting point,
and then it requires the mixing of wrought iron with it. As a result, the melting of the pig iron
requires a lower temperature.
2. The crucible process does not require difficult access to any of the necessary raw
materials. Because pig iron has a low melting point due to the high carbon content, charcoal and
coal are both suitable options for heat sources that can be used in this process. The process does
not require temperatures that are very high. (Craddock et al., 2017)
3. The production method used results in a relatively uncontaminated steel product. This
is because fluxes were utilized, which came very close to eliminating all of the impurities
entirely. After fluxes were added to the liquid pig iron, the impurities were able to easily float to
the surface, where they were subsequently removed.
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4. The steel that is made using this method has a high percentage of carbon in it,
somewhere between 1.5 and 2.0 percent. Because of this, it was able to be utilized in the
production of tools for cutting and drilling, such as blades and swords. Because of the high
carbon content, the steel has a hard and tough surface, making it capable of cutting a wide
variety of other materials. (Merv, 2012)
5. The crucible process yields steel that is fairly consistent throughout its structure. This
was possible because the steel had completely melted, which made it possible for the carbon to
dissolve uniformly throughout the liquid steel. Because of this, the substantial amount of
blacksmithing that had been required in the past to homogenize the steel was no longer
necessary.
6. The Crucible process was a key factor in the development of the industrial revolution.
This is due to the fact that the steel that was produced was capable of being cast into a variety of
shapes. This allowed for the mass production of machines with intricate shapes like engine
blocks for vehicles, which were previously impossible. Because of its resistance to shock and
corrosion as well as its ability to self-lubricate, the high-carbon steel that was obtained through
this process was suitable for use in the construction of bases for heavy machines. Because of this,
a massive industrial revolution took place.
7. The Crucible process made use of resources that were not initially regarded as being as
useful. This procedure consisted of mixing wrought iron with molten pig iron, which resulted in
the incorporation of carbon into the wrought iron. Because of this, it was useful and appropriate
for a wide variety of applications that required materials with qualities such as resistance to
shock and corrosion, as well as hardness and toughness. (Gilmer, 1906)
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8. The crucible process resulted in steel with high-quality characteristics. It had a higher
resistance to corrosion and wear, was more durable, and had a lower brittleness. The presence of
elements such as chromium, which caused an oxide layer to form, contributed to the material's
resistance to corrosion. Because carbon gave it its hardness and toughness, it was able to
withstand shock. Because it possessed all of these qualities, the steel that resulted from this
process was usable in a wide variety of contexts.
Disadvantages of Crucible Process
1.
1. Ineffectiveness in the operation of the business. There are some cases in
which efficiency levels are as low as 12 percent. The utilization of crucible furnaces as a
method is no longer an efficient approach when higher production quantities are being
processed. This is as a result of the comparatively high specific energy consumption that
is currently being encountered.
2.
2. A significant amount of air pollution There are significant amounts of
gas emissions, including those caused by nitrogen oxides, as a result of the high
temperatures in the furnace and the oxidation of the nitrogen. These factors combine to
produce the emissions.
3.
3. Exceptionally high operating costs on a global scale. When manual
charging is used, the costs associated with running the business are significantly
increased. In addition, in order for the metal to be utilized for subsequent charging, it
must first be completely dried out. This is due to the fact that the utilization of wet charge
material can result in the ejection of metal, which places the workers in a precarious
position.
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4. Size limitations. Because the pressure that is applied to the molten metal
during injection is lower than the pressure that is applied during cold chamber die
casting, the size of the components that can be produced using the hot chamber method is
restricted. This is because the pressure that is applied during injection to the molten metal
is lower than the pressure that is applied during cold chamber die casting.
5.
5. The production rates are considered to be on the lower end. The
utilization of crucible furnaces as a method is no longer an efficient approach when
higher production quantities are being processed. The primary factor that contributes to
the occurrence of this phenomenon is the relatively high total amount of energy
consumed.
6.
6. An increase in the expense of obtaining capital. These furnaces are
vessels that are lined with refractory and employ resistance heating elements that are
mounted in the roof of the furnace above the hearth. These furnaces are used to heat
materials. The prices that are typically associated with the acquisition of these materials
are quite high.
7.
7. The capacity for refining that can be achieved through the use of
induction furnaces in a foundry is insufficient. The charge materials must not contain any
oxides and have a composition that is completely understood. In addition, due to the
possibility that certain alloying elements will be lost as a result of oxidation, it is
necessary to reintroduce those elements into the melt.
8.
8. The heating elements need to be replaced on a regular basis to ensure
proper operation. Burners in furnaces that are powered by fuel produce a direct flame, but
the air intake on these devices can be problematic at times. Oxidation, which is caused by
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excess air and direct flame, is the culprit behind the damage that has been done to the
surface of the crucible. It is possible for oxidation to take place in the molten metal if the
temperature is maintained at a level that is lower than the metal's melting point for an
extended period of time. Because of the dangerously high temperature, the heating
elements needed to be replaced as a result of the damage they sustained. Corrosion and
degradation of engineering materials. The corrosion behavior of magnesium alloys is
influenced substantially by impurities. The heavy metals contained as impurities form
galvanic cells and enhance the corrosion rate.
9.
Crucible furnaces are of small capacity. The small capacity furnaces are
used for small melting applications or exclusively as holding furnaces which causes low
output production of materials being produced.
10.
Crucible process has higher fuel consumption. With fuel firing the energy
consumption per ton of melting material does not only depend from the design of the
furnace and the size of the crucibles.
11.
Crucible process may lead to crucible exploding. If the heating is too
rapid, the steam is evolved too quickly to escape from the crucible body, causing an
enormous increase in pressure which will rupture the crucible, or in extreme cases, cause
it to explode.
Conclusion
In a nutshell, the method is still implemented in a considerable number of distinct
applications across a wide range of industries. The efficiency with which resources are utilized
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and the management of the costs involved in the production of materials that are non-corrosive
and hard, which are utilized in modern industry today, is referred to as the effectiveness of the
utilization of the resources. As a consequence of this, it is of the utmost importance to
concentrate on the manner in which the benefits of the process can be maximized while at the
same time attempting to find solutions for the problems that the process presents, such as its
inefficiency and the hazardous conditions to which it subjects the workers and the people.
Consequently, it is of the utmost importance to concentrate on the manner in which the benefits
of the process can be maximized while at the same time attempting to find solutions for the
problems that the process This method has been shown to be effective and cost-effective in
processing the materials that need to be produced. This is due to the fact that it requires fewer
technically complex processes and also makes use of straightforward materials that are easily
accessible within the environment. It is therefore effective to ensure that the industry makes
more adjustments towards the way that the process is carried out, in order to solve the challenges
such as the inefficiency of the heating process and the compromised quality of the metals that are
produced as a result of the process. In order to solve these challenges, it is effective to ensure that
the industry makes more adjustments towards the way that the process is carried out.
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