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How To Get The Maximum Percentage Yield In The Chemical Industry, the Rate Of Reaction And the Production Of Steel. by empressteemah

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How To Get The Maximum Percentage Yield In The Chemical Industry, the Rate Of Reaction And the Production Of Steel.
<p class="MsoNormal"><span style="font-size: 1rem;">This is sequel to my last post on&nbsp;</span><a href="!/@empressteemah/detailed-explanation-1570278486" target="_blank">Detailed Explanations on Reactions, Equations, Energy and Equilibria to a Layman.</a><span style="font-size: 1rem;"> &nbsp;From
that post, I explained some basic concepts of chemical equation, relative
molecular mass, and using equations in industry. Going through the </span><a href="!/@empressteemah/detailed-explanation-1570278486" target="_blank">post</a><span style="font-size: 1rem;">, you
should now be able to use balanced equations to calculate the masses of
substances involved in reactions. We have found that 10 tonnes of Iron(III)
oxide can give 7.0 tonnes of iron. The mass of iron produced is known as the
yield. But chemists could never achieve this yield in a real blast furnace.
Therefore we say that the calculation from the balanced equation gives the
theoretical yield, which is the maximum amount if all the reactants are
converted into products.There are many reasons why the theoretical yield is not
achieved: reactions may not be finished in the time available, or some of the
product may be lost during the purification procedure.</span></p><p class="MsoNormal"><img src="" data-filename="ugk2qfp5et1weanr1n3i" style="width: 527.528px;"><span style="font-size: 1rem;"><br></span></p><p class="MsoNormal"><div style="text-align: center;"><sup><a href="" target="_blank">New polypropylene plant PP3 in the Slovnaft oil refinery (Bratislava, Slovakia), Mikulova - Own work, CC BY-SA 3.0.</a></sup></div></p><p class="MsoNormal"><span lang="">In industry or the laboratory, if there is
more than one reactant, the reactant that is in short supply is called the
limiting reactant. This is the reactant that determines the maximum amount of
product that can be made. The other reactants are said to be in excess. In the
case of reducing iron(III) oxide in the blast furnace, the limiting reactant
will be the Iron (III) oxide because it is cheaper to have an excess of carbon
monoxide.<o:p></o:p></span></p><p class="MsoNormal"><span lang="">The actual yield from a reaction can be found
only by doing the reaction. From 10.0 tonnes of iron(III) oxide, it is going to
be less than 7.00 tonnes of iron. Percentage yield is a convenient way of
expressing how close the actual yield is to the theoretical yield.<o:p></o:p></span></p><h4 align="center" style="text-align:center"><span lang="">Percentage yield =
actual yield / theoretical yield </span><span lang="">× </span><span lang="">100%<o:p></o:p></span></h4><p class="MsoNormal"><span lang="">Industrial processes aim for 100 per cent
yield. The closer they get, the less is the waste of raw material.<o:p></o:p></span></p><h2><span lang="">Let’s discuss about atom economy….<o:p></o:p></span></h2><p class="MsoNormal"><span lang="">Even with 100 per cent yield there may still
be a huge wastage of resources through the production of unwanted by-products.
This is where the term atom economy comes in. It was first put forward by Barry
Trost in the United States in 1991. As part of a new way of thinking called
Green chemistry. He urged chemists to consider how many atoms from the starting
materials actually ends up in useful products. If the atoms from the reactants
do not end up in useful products, then they end up in waste products.<o:p></o:p></span></p><h4 align="center" style="text-align:center"><span lang="">Atom economy = mass of
desired product / total mass of reactants </span><span lang="">×</span><span lang=""> 100%<o:p></o:p></span></h4><p class="MsoNormal"><span lang="">Let’s consider again the reduction of the iron
ore, Fe<sub>2</sub>O<sub>3</sub>.<o:p></o:p></span></p><h4 align="center" style="text-align:center"><span lang="">Fe<sub>2</sub>O<sub>3</sub>(s)
+ 3CO(g) </span><span lang="">→ </span><span lang="">2Fe(s) + 3CO<sub>2</sub>(g)<o:p></o:p></span></h4><p class="MsoNormal"><span lang="">The desired product is iron and in the
equation 2 moles are produced:<o:p></o:p></span></p><h4 align="center" style="text-align:center"><span lang="">2 </span><span lang="">×</span><span lang=""> 56 g = 112 g<o:p></o:p></span></h4><p class="MsoNormal"><span lang="">The masses of the reactants:<o:p></o:p></span></p><h4 align="center" style="text-align:center"><span lang="">1 mol Fe<sub>2</sub>O<sub>3</sub>
(= 160 g) + 3 mol CO = 3 </span><span lang="">×</span><span lang=""> 28 (=84 g)<o:p></o:p></span></h4><p class="MsoNormal"><span lang="">Total masses of reactants = 244 g.<o:p></o:p></span></p><h4 align="center" style="text-align:center"><span lang="">Atom economy = mass of
desired product / total mass of reactants </span><span lang="">× </span><span lang="">100% = 112 / 244 = 45.9%<o:p></o:p></span></h4><p class="MsoNormal"><span lang="">So almost 54 per cent of the starting
materials are lost, in this case to the atmosphere where the carbon dioxide
contributes to the greenhouse effect and global warming. However, if there were
an economic use for carbon dioxide then the atom economy would be 100 per cent.</span></p><p class="MsoNormal" style="text-align: center; "><img src="" data-filename="k00oiqcgvjdebx36rjmi" style="width: 527.528px;"><span lang=""><o:p><br></o:p></span></p><p class="MsoNormal" style="text-align: center; "><a href="" target="_blank"><sup>Atom economy. Astrid 91 - Own work, CC BY-SA 4.0</sup></a><span lang=""><o:p><br></o:p></span></p><h2><span lang="">A brief introduction to rate of reaction<o:p></o:p></span></h2><p class="MsoNormal"><span lang="">The aim of industrial chemistry is to get as
close as possible to a 100 per cent yield. However, in producing any chemical
economically, the yield from a reaction is just one of the factors involved.
Another very important factor is the rate of reaction. It is no use having a
high yield of iron in a process that is extremely slow.<o:p></o:p></span></p><p class="MsoNormal"><span lang="">As a simple definition:<o:p></o:p></span></p><h4 align="center" style="text-align:center"><span lang="">The rate of a reaction
is the amount of substance formed per unit of time.<o:p></o:p></span></h4><p class="MsoNormal"><span lang="">The rate could be in moles per second. For
industry, it is more convenient to give the rate as the mass of substance, such
as kilograms or tonnes, formed per unit of time. Reactions can be very fast and
uncontrolled, such as a gas explosion. Reactions can also be very slow, as in
the rusting of iron.<o:p></o:p></span></p><p class="MsoNormal"><span lang="">An industrial chemist needs to control the
rate of a reaction. This can either mean speeding it up or slowing it down. In
industry, the rate often needs to be increased so that the amount of product
formed in, say, a day is enough to make a profit.</span></p><p class="MsoNormal" style="text-align: center; "><img src="" data-filename="g7miouivkdb8aytwawuo" style="width: 527.528px;"><span lang=""><o:p><br></o:p></span></p><p class="MsoNormal" style="text-align: center; "><a href="" target="_blank"><sup>Generic potential energy diagram showing the effect of a catalyst in a hypothetical endothermic chemical reaction.  Vinay.bhat. public domain</sup></a><span lang=""><o:p><br></o:p></span></p><h2><span lang="">So, what are those factors that affect that rate of reaction?<o:p></o:p></span></h2><p class="MsoNormal"><span lang="">Chemists control the rate of a reaction by
changing the conditions of the reaction. These are some of the conditions that
affect reaction rates,<o:p></o:p></span></p><ul><li><span lang=""><b>Temperature</b>:
an increase in temperature makes a reaction go faster (except for those
involving enzymes)</span></li><li><b style="font-size: 1rem;">Pressure:</b><span style="font-size: 1rem;">
increasing pressure increases the rate of reactions that involve gases.</span></li><li><b style="font-size: 1rem;">Concentration</b><span style="font-size: 1rem;">:
increasing the concentration normally increases the rate of reaction.</span></li><li><b style="font-size: 1rem;">Surface</b><span style="font-size: 1rem;">
</span><b style="font-size: 1rem;">area</b><span style="font-size: 1rem;"> </span><b style="font-size: 1rem;">of</b><span style="font-size: 1rem;"> </span><b style="font-size: 1rem;">reactant:</b><span style="font-size: 1rem;"> an increase
in surface area increases the rate of reaction.</span></li><li><b style="font-size: 1rem;">Catalyst:</b><span style="font-size: 1rem;">
the addition of a catalyst usually increases the rate of reaction.</span></li></ul><p class="MsoNormal"><span lang="">Reactions involve the rearrangement of atoms
when bonds are broken and others are made, This rearrangement seldom takes
place spontaneously; the particles normally need to collide with each other.
All the conditions listed above will change the collision rate between
particles. And if the collision rate is increased then the rate of reaction
will increase, changing temperature, pressure, concentration and surface area
can control the rate of reaction. However, these factors can also reduce the
yield of an industrial process, so there is often a compromise between rates of
reaction and yield. Remember, a major concern is the economics of the process –
that is, making product quickly enough to give the maximum profit, I will look
in this compromise in more detail later in this article.<o:p></o:p></span></p><h2><span lang="">Here’s another type of reaction: The chemical reactions and
energy changes<o:p></o:p></span></h2><p class="MsoNormal"><span lang="">All chemical reactions involve a change of
energy, meaning the transfer of energy to or from chemicals in the reaction.
This is crucial not only to industry, but also to the reactions of life itself.
In many chemical reactions, energy is given out by the reactants as they form
products, causing the temperature of the surroundings to rise. Such reactions
are known as exothermic reactions.<o:p></o:p></span></p><p class="MsoNormal"><span lang="">In the blast furnace, blasts of hot air at 750
°C are blown in at the base and start a reaction between coke and oxygen:<o:p></o:p></span></p><h4 align="center" style="text-align:center"><span lang="">C + O<sub>2</sub></span><span lang="">
→ </span><span lang="">CO<sub>2</sub><o:p></o:p></span></h4><p class="MsoNormal"><span lang="">This reaction is highly exothermic, raising
the temperature at the base of the furnace to about 2000 °C. This is because
the stored energy in carbon and oxygen is greater than the stored energy in
carbon dioxide. Stored energy is known as enthalpy, symbol H. It is not
possible to measure enthalpy, but enthalpy changes can easily be found by
measuring temperature changes during reactions at constant pressure. Enthalpy
changes are given the symbols </span><span lang="">Δ</span><span lang="">H: </span><span lang="">Δ</span><span lang=""> is a Greek letter pronounced ‘delta’ and is used by chemists to mean ‘change
of’.<o:p></o:p></span></p><p class="MsoNormal"><span lang="">In the coke and oxygen reaction, the energy
released is 394 kilojoules (kJ) for every mole of carbon that reacts. So we
write:<o:p></o:p></span></p><h4 align="center" style="text-align:center"><span lang="">C(s) + O<sub>2</sub>(g)
</span><span lang="">→</span><span lang=""> CO<sub>2</sub> (g)&nbsp; </span><span lang="">ΔH = -394 kJ mol<sup>-1</sup></span><span lang=""><o:p></o:p></span></h4><p class="MsoNormal"><img src="" data-filename="zz5hxobgkm1j4exbmuvt" style="width: 300px; float: left;" class="note-float-left"><sup><a href="" target="_blank">This example is demonstrating that energy has been released and Delta H is negative, meaning that the reaction is spontaneous and taking place., Public Domain</a></sup></p><p class="MsoNormal"><span lang="">Notice that </span><span lang="">Δ</span><span lang="">H has a negative sign. This is because as the reaction proceeds, energy
is lost. This energy heats up the surroundings, in this case the contents of
the blast furnace. The reaction and its enthalpy changes can be shown in an
energy level diagram, also called an enthalpy level diagram. State symbols
should always be shown in chemical equations when dealing with energy from
chemical reactions. Remember that, (s) = solid, (l) = liquid and (g) = gas.<o:p></o:p></span></p><p class="MsoNormal"><span lang="">Not all reactions are exothermic. Endothermic
reactions are the opposite of exothermic reactions. In endothermic reactions
energy is taken in by the reactants to form products. The energy comes from the
surroundings, which lose energy and cool down.<o:p></o:p></span></p><p class="MsoNormal"><span lang="">The carbon dioxide produced at the base of the
blast furnace reacts with more coke to produce carbon monoxide. This is an
endothermic reaction.<o:p></o:p></span></p><h4 align="center" style="text-align:center"><span lang="">CO<sub>2</sub>(g) +
C(s) </span><span lang="">→ </span><span lang="">2CO(g)&nbsp; </span><span lang="">ΔH</span><span lang=""> = +173 kJmol<sup>-1</sup><o:p></o:p></span></h4><p class="MsoNormal"><span lang="">The plus sign shows that carbon monoxide takes
in energy when it is formed. As this reaction occurs in the middle of the
furnace, this is one of the reasons why the blast furnace becomes cooler
towards the top. This is an easy way to remember what exothermic and
endothermic mean: Energy <b>ex</b>its in <b>ex</b>othermic reactions. Look for
the minus sign (</span><span lang="">ΔH is negative). Energy <b>en</b>ters in <b>en</b>dothermic
reactions. Look for the plus sign (ΔH is positive)</span><span lang=""><o:p></o:p></span></p><h2><span lang="">Now, what is a blast furnace and what is it used for?<o:p></o:p></span></h2><p class="MsoNormal"><span lang="">The blast furnace smelts the iron ore. An ore
is a naturally occurring group of minerals from which a metal, or metals, can
be extracted for a profit. Smelting means that the ore is melted mixed with the
other reactants and reduced to the metal. The reaction of iron ore with coke,
limestone and hot air, produces the iron. The iron-making process needs
high-quality iron ore that contains at least 60 per cent iron. Most iron ores
contain impurities such as sand (silicon(IV) oxide, SiO<sub>2</sub>), sulphur
compounds and phosphorus compounds so, if not pure enough, the ore has to be
pre-refined to increase the percentage of iron.</span></p><p class="MsoNormal" style="text-align: center; "><img src="" data-filename="jz1gjzgnq8k3d6g754aa" style="width: 527.528px;"><span lang=""><o:p><br></o:p></span></p><p class="MsoNormal" style="text-align: center; "><a href="" target="_blank"><sup>A blast furnace, Pixabay.</sup></a><span lang=""><o:p><br></o:p></span></p><p class="MsoNormal"><span lang="">The blast furnace lining has to last for many
years to save the cost of replacing it and to minimize shutdown time for
replacement work, since the loss of production may cost millions of pounds.<o:p></o:p></span></p><h2><span lang="">What are the conditions in the blast furnace?<o:p></o:p></span></h2><p class="MsoNormal"><span lang="">Some of the blast furnace reactions require
high temperatures, so a great input of energy is needed. Fortunately, the
reaction of carbon with oxygen to give carbon dioxide provides the energy,
since it is an extremely exothermic reaction. The blasts of hot air, which give
the blast furnace its name, are enriched with oxygen. The concentration of
oxygen, higher than in air, speeds up the reaction. The faster the rate of reaction,
the more the energy produced by the exothermic reactions. In this way, the high
temperatures are easier to maintain. The carbon dioxide formed near the base
travels upwards through the melt and solids, and is converted into carbon
monoxide. It is the carbon monoxide rather than the solid carbon that reduces
most of the iron ore, since gases react faster than solids. The use of pelletised
reactants ensures that carbon monoxide comes into very close contact with the
iron(III) oxide. This helps to speed up the reaction because the surface area
of the ore has been increased.<o:p></o:p></span></p><p class="MsoNormal"><span lang="">Finally, there are the reactions involving
limestone. Limestone (calcium carbonate) decomposes into calcium oxide (lime)
and carbon dioxide in the heat of the furnace:<o:p></o:p></span></p><h4 align="center" style="text-align:center"><span lang="">CaCO<sub>3</sub>(s) </span><span lang="">→
</span><span lang="">CaO(s) + CO<sub>2</sub>(g)<o:p></o:p></span></h4><p class="MsoNormal"><span lang="">The calcium oxide removes impurities such as
sand (silicon(IV) oxide, SiO,) as liquid slag. The reaction for sand is:<o:p></o:p></span></p><h4 align="center" style="text-align:center"><span lang="">CaO(s) + SiO<sub>2</sub>(s)
</span><span lang="">→ </span><span lang="">CaSiO<sub>3</sub>(s)<o:p></o:p></span></h4><p class="MsoNormal"><span lang="">Slag and iron are both liquids at the high
temperatures of the furnace. Conveniently, the less dense slag floats on top of
the more dense iron, so they are tapped off separately at different levels. The
production of iron is a continuous process. In continuous processes, raw
materials are constantly added and the products are continually removed. A
continuous process is a very efficient and cost-saving way to produce materials
in large quantities. By comparison, in batch processes, the reactor vessel must
be closed down and reset to make another batch. This is expensive because there
is ‘dead time’ when no product is being produced. However, a range of products
can be made in the same vessel, although care is exercised to ensure no
contamination occurs. For small quantities, the batch process is usually more
cost effective.</span></p><p class="MsoNormal" style="text-align: center; "><img src="" data-filename="xnwgjffy9zdtebjv97jz" style="width: 527.528px;"><span lang=""><o:p><br></o:p></span></p><p class="MsoNormal" style="text-align: center; "><a href="" target="_blank"><sup>Blast Furnace. Tosaka - Own work, CC BY 3.0. 1: Iron ore + Calcareous sinter 2: coke 3: conveyor belt 4: feeding opening, with a valve that prevents direct contact with the internal parts of the furnace 5: Layer of coke 6: Layers of sinter, iron oxide pellets, ore, 7: Hot air (around 1200°C) 8: Slag 9: Liquid pig iron 10: Mixers 11: Tap for pig iron 12: Dust cyclon for removing dust from exhaust gasses before burning them in 13 13: air heater 14: Smoke outlet (can be redirected to carbon capture &amp; storage (CCS) tank) 15: feed air for Cowper air heaters 16: Powdered coal 17: cokes oven 18: cokes bin 19: pipes for blast furnace gas</sup></a><span lang=""><o:p><br></o:p></span></p><h2><span lang="">How the wastes in the smelting of Iron ore are being disposed<o:p></o:p></span></h2><p class="MsoNormal"><span lang="">The waste gases and slag could cause pollution
problems, but ways have been found to minimise them. Much of the slag goes to
build roads and make cement. Some of it is even used to insulate houses:
Rockwool, used for non-flammable loft insulation, is produced by blowing air
into the molten slag to make it light and fluffy.<o:p></o:p></span></p><h2><span lang="">How steel is made from Iron.<o:p></o:p></span></h2><p class="MsoNormal"><span lang="">Iron from a blast furnace is impure, brittle
and not very strong, so most iron produced is changed immediately into steel.
Steel is the name given to countless alloys that contain iron, carbon and,
usually, small amounts of other elements. An alloy is a mixture of two or more
elements, at least one being a metal. The elements are mixed when they are
molten and allowed to cool down to form a uniform solid.<o:p></o:p></span></p><p class="MsoNormal"><span lang="">Alloys have different properties from the
elements that form them. It is the addition of different elements to iron that
changes the properties of the alloy and so makes steels such versatile
materials.<o:p></o:p></span></p><p class="MsoNormal"><span lang="">Different types of steel have properties that
iron lacks, giving steel a very wide range of uses such as<o:p></o:p></span></p><p class="MsoNormal"><span lang="">(a) Fractured bones are held together by
permanent steel pins<o:p></o:p></span></p><p class="MsoNormal"><span lang="">(b) The Thames Barrier is mainly steel and
concrete<o:p></o:p></span></p><p class="MsoNormal"><span lang="">(c) Well over half the components of a typical
car are made of steel, including the body shell, clutch plates and engine.<o:p></o:p></span></p><p class="MsoNormal"><span lang="">(d) The Fruit Drop at Blackpool is made of
steel to meet high safety standards.<o:p></o:p></span></p><h2><span lang="">What are carbon steels?<o:p></o:p></span></h2><p class="MsoNormal"><span lang="">As the name suggests, carbon steels are alloys
of mainly iron with some carbon. The sheet steel used in car bodies contains
just 0.2 per cent of carbon, an amount that makes it easy to bend and shape. As
the carbon content of steel is increased, the steel becomes stronger and more
rigid. Most of the steel used to construct a bridge, which needs some flexibility,
contains between 0.3 and 0.6 per cent carbon. The steel used in drill bits has
to be very hard and contains up to 1.5 per cent carbon. It is tempting to think
that by increasing the carbon content the steel would carry on strengthening.
Unfortunately, this is not the case, and at just 4 per cent carbon, steel
becomes very brittle.<o:p></o:p></span></p><h2><span lang="">So, what about alloy steels?<o:p></o:p></span></h2><p class="MsoNormal"><span lang="">Alloy steels are steels that contain one or
more other metals. These metals include manganese, tungsten, chromium and
vanadium. Stainless steels are probably the best-known alloy steels, containing
at least 12 per cent chromium. The chromium increases steel’s rust resistance.
A common stainless steel is called 18-8 and contains 18 per cent chromium and 8
per cent nickel, a composition you will find in some cutlery. Steels that
contain tungsten are very hard-wearing. Adding molybdenum (with certain other elements) enables drill bits to retain their cutting edge, even when hot.
Spacecraft use titanium steel because it can withstand the high temperatures of
re entry.<o:p></o:p></span></p><h2><span lang="">THE WORLD OF STEEL MAKING<o:p></o:p></span></h2><p class="MsoNormal"><span lang="">The main process for converting iron into
steel is the basic oxygen process. Impure iron from a blast furnace is known as
pig iron and contains About 4 per cent carbon, together with other elements
such as silicon, manganese and phosphorus. To convert the iron into steel, the
carbon content Is lowered and other elements are removed by reacting them with
oxygen. An oxygen lance is lowered into the basic oxygen furnace and oxygen is
blown into the molten iron at twice the speed of sound.<o:p></o:p></span></p><p class="MsoNormal"><span lang="">The impurity elements form oxides. These are
some of the reactions:<o:p></o:p></span></p><h4 align="center" style="text-align:center"><span lang="">2C(s) + O<sub>2</sub>(g)
</span><span lang="">→ </span><span lang="">2CO(g)<o:p></o:p></span></h4><h4 align="center" style="text-align:center"><span lang="">2Mn(s) + O<sub>2</sub>(g)
</span><span lang="">→ </span><span lang="">2MnO(s)<o:p></o:p></span></h4><h4 align="center" style="text-align:center"><span lang="">4P(s) + 5O<sub>2</sub>(g)
→ P<sub>4</sub>O<sub>10</sub>(s)<o:p></o:p></span></h4><h4 align="center" style="text-align:center"><span lang="">Si(s) +O<sub>2</sub>(g)
</span><span lang="">→ </span><span lang="">SiO<sub>2</sub>(s)<o:p></o:p></span></h4><p class="MsoNormal"><span lang="">Being a gas, carbon monoxide bubbles out of
the liquid mixture. Both SiO<sub>2</sub> and P<sub>4</sub>O<sub>10</sub> are
acidic oxides and are removed by adding lime (calcium oxide), which is a basic
oxide – hence the word ‘basic’ in the basic oxygen process.</span></p><p class="MsoNormal" style="text-align: center; "><img src="" data-filename="agww50l34l3asvyghncv" style="width: 508.991px;"><span lang=""><o:p><br></o:p></span></p><p class="MsoNormal" style="text-align: center; "><a href="Ä2.jpg" target="_blank"><sup>Steel Mill. Riksantikvarieämbetet / Pål-Nils Nilsson, CC BY 2.5 se</sup></a><span lang=""><o:p><br></o:p></span></p><p class="MsoNormal"><span lang="">They react to form a slag that floats on top
of the molten steel. These chemical reactions with oxygen are highly exothermic
and generate great heat, so the reactions inside the furnace keep the contents
molten. In fact, the temperature has to be stopped from becoming too high.
Scrap iron and steel are added to prevent the mixture from overheating. Because
as the mixture melts it takes in energy – melting is an endothermic process. If
the temperature rose unchecked, then the rate of the exothermic reactions would
increase, causing yet more energy to be released and making the reaction faster
still. Eventually, the process would be uncontrollable and the furnace lining
would be damaged.<o:p></o:p></span></p><p class="MsoNormal"><span lang="">It is the job of industrial chemists known as
metallurgists to ensure that the reaction conditions of the steel making
process are optimized. They also establish and monitor the best mix of elements
for a particular type of steel to match customer demand.<o:p></o:p></span></p><h2><span lang="">Steel – matching supply and demand<o:p></o:p></span></h2><p class="MsoNormal"><span lang="">Steel manufacture is a business, and so the
production of steels must be tied closely with long-term planning to sell it.
An industrial plant the size of iron and steel works cannot run economically if
it has to start and stop manufacture to match short-term demands. A blast
furnace works efficiently only if it is running all the time. Also, if furnace
production is stopped, the furnace has to cool down and then be cleaned out.
Starting it up again is a costly and difficult process that requires a lot of
energy. But if the production of steel outstrips demand, the only economic
solution may be to close down the whole steel works. So to keep steel works operating,
the staff who are in charge of sales constantly search for new markets.<o:p></o:p></span></p><h2><span lang="">Finally, saving on energy.<o:p></o:p></span></h2><p class="MsoNormal"><span lang="">We have seen that steel making has very
expensive energy requirements. About 15 per cent of the cost of making steel is
spent on the energy that the process consumes, so companies are continually on
the look-out for ways to make savings. Building the steel works next to the
blast furnace allows molten iron to be used as soon as it is made. Since the
iron does not cool much between processes, its energy is not wasted. Also, the
energy from hot waste gases and slag can be transferred to other parts of the
operation. The waste gases can even be burnt to release energy.<o:p></o:p></span></p><h2><span lang="">Thanks.<o:p></o:p></span></h2><h2><span lang="">REFERENCES<o:p></o:p></span></h2><p>

</p><p class="MsoNormal"><a href="" target="_blank">how-to-calculate-percent-yield-definition-formula</a><span lang="">&nbsp;</span></p><p class="MsoNormal"><a href="" target="_blank">youtube video on percentage yield and calculations.</a><span lang=""><br></span></p><p class="MsoNormal"><a href="" target="_blank"></a><span lang=""><br></span></p><p class="MsoNormal"><a href="" target="_blank"></a><span lang=""><br></span></p><p class="MsoNormal"><a href="" target="_blank"></a><span lang=""><br></span></p><p class="MsoNormal"><a href="" target="_blank"></a><span lang=""><br></span></p><p class="MsoNormal"><a href="" target="_blank"></a><span lang=""><br></span></p><p class="MsoNormal"><a href="" target="_blank"></a><span lang=""><br></span></p><p class="MsoNormal"><a href="" target="_blank"></a><span lang=""><br></span></p><p class="MsoNormal"><a href="" target="_blank"></a><span lang=""><br></span></p><p class="MsoNormal"><a href="" target="_blank"></a><span lang=""><br></span></p><p class="MsoNormal"><a href="" target="_blank"></a><span lang=""><br></span></p><p class="MsoNormal"><a href="" target="_blank">Factors that affect reaction rates.</a><span lang=""><br></span></p><p class="MsoNormal"><a href="" target="_blank"></a><span lang=""><br></span></p><p class="MsoNormal"><a href="" target="_blank"></a><span lang=""><br></span></p><p class="MsoNormal"><a href="" target="_blank"></a><span lang=""><br></span></p><p class="MsoNormal"><a href="" target="_blank"></a><span lang=""><br></span></p><p class="MsoNormal"><a href="" target="_blank"></a><span lang=""><br></span></p><p class="MsoNormal"><a href="" target="_blank"></a><span lang=""><br></span></p><p class="MsoNormal"><a href="" target="_blank"></a><span lang=""><br></span></p><p class="MsoNormal"><span lang=""><br></span></p>
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