Lecture №9.
Non-ferrous metals and alloys.
1. Production of copper, aluminum, titanium
2 . Alloys on the basis of copper, aluminum, titanium.
Production of copper.
There are two ways of extraction of copper from ores and concentrates -
pyrometallurgical and hydrometallurgical. From them, the basic is the first way.
Production of copper consists of the following main stages:
1. Roasting of ores and concentrates make in multihearth furnaces of mine type
with a mechanical pulling of ore or in "in a boiling layer" which is more
progressive. Roasting pursues the aim as much as possible to lower the content
in sulfur ore. When roasting copper ores and concentrates is removed to 50% of
sulfur.
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2. Receiving copper matte.
The burned concentrate or the ore called candle end, arrive on melting for
receiving copper matte. Reflective furnaces are applied to melting.
3. Receiving draft copper.
Receiving draft copper is carried out in converters of horizontal type with
lateral blasting. The modern copper-smelting converter has length 6-10m and
outer diameter 3-4m. Furma for air inflation in number of 46-52 pcs of diameter
near 50mm are located on a forming surface of the converter. As a result of a
matte purge which lasts some hours, draft copper and converter slag turns out.
4. Copper refinement.
The received draft copper contains sulphurous connections, oxides, iron and
other impurity and therefore can't be used in such look for the technical
purposes. Draft copper subject to fire and electrolytic refinement, harmful
impurity thus are removed and it is possible to extract the precious metals which
were in it. Now to 95% of draft copper are exposed to electrolytic refinement.
For electrolysis we produce wooden or concrete bathtubs, lined inside with lead
or vinyl plastic. Copper cathodes are produced from thin sheets of pure copper,
and anode plates - from copper after fire refinement.
Aluminum production.
The main ore for receiving aluminum are bauxites.
Technological process of receiving aluminum consists of three main stages:
1 . Receiving alumina from ores.
2 . Receiving aluminum from alumina.
3 . Aluminum refinement.
For receiving alumina from ores, the broadest application was received by
ways of leaching from ores. For this purpose small crushed ore we process
caustic sodium or soda. Leaching is made in special autoclaves at a temperature
150-200ºС and pressure about 12 atm. By this way 85-87% from all received
alumina is taken. The received oxide of aluminum represents a strong chemical
compound with a temperature of melting of 2050ºС.
Aluminum is received by electrolysis from the alumina dissolved in the melted
cryolitas, in special bathtubs. The bathtub has a steel casing, inside lined with a
heat-insulating fireclay brick, and hearth and walls are laid out by coal blocks.
At electrolysis, alumina and carbon of anodes is spent, and aluminum and
carbon oxides turn out.
At electrolysis, for production of 1t aluminum we spend near 2 t of alumina,
0,1 t cryolitas, 0,7 t anode weight and 17000-18000 kW h electric power.
The aluminum received by electrolysis contains a number of impurities: metal,
nonmetallic and gaseous which worsen its properties. For receiving pure
aluminum, it is exposed to refinement by chlorination or electrolytic way. The
method of chlorination consists in aluminum purge chlorine in a ladle, in the
special camera at a temperature 750-760ºС within 10-12 min. Purity of the
received aluminum is 99,5-99,85%.
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To receiving aluminum of higher purity we apply electrolytic way of
refinement. For electrolyte we use fluoric and chloride salts with a melting
temperature slightly higher than temperature of melting of aluminum.
Production of titanium.
To production of titanium we apply mainly rutile, ilmenite and perovskite.
Due to the big affinity of titanium to oxygen, it isn't possible to restore it from
dioxide. Therefore dioxide of titanium at first transfer to tetrachloride of
titanium, and then from the last we receive pure metal.
For receiving the four-chloride titanium, rutile is mixed with chark, charcoal
or graphite and coal-tar pitch. From the received mix we produce pressing
briquettes which then in hermetically closed furnaces are calcinated at a
temperature 800-900ºС. The received porous briquettes are exposed to
chlorination in special installations at a temperature of 800-850ºС.
For recovery of titanium from tetrachloride there are some ways. Best of them,
widely adopted, is magnesium-thermal. Recovery of titanium is made by
magnesium in the special furnaces called reactors. For this purpose, magnesium
of high purity in the form of billets is loaded into steel glass of the reactor and
then the reactor is densely closed by a cover. Further air is pumped out from the
reactor, filled with argon and given there titanium tetrachloride.
For removal of metal and chloride magnesium, the received titanium is
exposed to refinement by vacuum separation. For this purpose a glass with a
reactionary weight is closed by a cover having openings, and then turned upside
down, established in the furnace, vacuum is created and heated.
The received titanium sponge is melted in arc vacuum furnaces, and metal is
spilled in ingots. Melting under vacuum allows in addition to clear the titanium
of moisture, hydrogen, and metal and chloride magnesium.
Alloys on the basis of copper.
Copper in pure form has red color, the more impurity in it, the break is rougher
and darker. Temperature of melting of copper 1083ºС, density is 8,92 g/cm ³.
Impurity has essential impact on physicomechanical characteristics of copper.
According to the content of impurity distinguish copper brands: MOO (99,99%
of copper)., МО (99,95%)., М1(99,9%), М2(99,7%).
Copper is produced of the following brands:
- cathodic - МВ4к, МООк, МОку, М1к.
- anoxic - МООб, МОб, М1б.
- cathodic melted - М1у.
The main advantages of copper as machine-building material are high warm
and conductivity, plasticity, corrosion resistance. To shortcomings of copper
refer low foundry properties and bad workability cutting.
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The alloying of copper is carried out for the purpose of giving to an alloy the
demanded mechanical, technological, antifrictional and other properties.
Alloys of copper classify:
1. On a chemical composition: brass, bronze, copper-nickel alloys.
2. On technology of processing: deformable, foundry and special
3. In relation to the thermal
Non-ferrous metals possess a number of specific properties. So, copper differs
high conductivity, aluminum and magnesium - small density, lead – plasticity,
tin, lead, zinc easily fusibility, etc. Therefore the listed metals, despite high cost,
are widely applied in the industry in the form of making elements of color
alloys. Alloyage of one non-ferrous metals with others with formation of alloys
in some cases considerably improves their valuable properties. Below the short
characteristic of a number of widespread non-ferrous metals and alloys is given.
Copper of the M1 brand contains to 0,1% of impurity, possesses high
conductivity and is applied to conductors of electric current.
L68 brand brass (32% of zinc, the rest copper) possesses high plasticity, anti-
corrosion and is used more often for production of products by rolling and
stamping (wire, sheets, pipes, etc.).
LS59-1 brand brass (40% of zinc, 1% of lead, the rest copper) possesses a
good workability cutting. It is applied in the form of color molding, and also the
products made by rolling or pressing (sheets, bars, pipes, plugs, nuts, etc.).
Bro10 brand bronze (10% of tin, the rest copper) possesses good foundry
properties and therefore is applied to color shaped molding. The microstructure
of tin bronze consists from non-uniform firm α-solution and eutectoid. Dark
sites non-uniform α-solution are rich with copper, light – with tin.
Alloys on the basis of titanium.
Titanium-silver-white metal of low density (4,5 g/cm ³) with high mechanical
durability, corrosion and chemical resistance. Temperature of melting of
titanium 1660ºС, with carbon it forms very firm carbides. Titanium is well
forged, rolled and pressed.
Mechanical properties of titanium is defined by degree of its purity. Impurity
of oxygen, nitrogen and carbon, various connections forming with titanium,
have essential impact on its properties. Hydrogen causing embrittlement of
titanium belongs to harmful impurity.
Titanium alloys classify on:
- technological appointment on foundry and deformable.
- mechanical properties - low (to 700 MPa), average (700-1000 MPa) and high
(more than 1000 MPa) durabilities.
- operational characteristics - heat resisting, chemically resistant, etc.,
- relation to thermal processing - strengthened and not strengthened.
- structure - (α, α +β, β-alloys).
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Alloys on the basis of aluminum.
AL2 brand alpax (10-13% of silicon, the rest aluminum) possesses corrosion
resistance and good foundry properties, is applied to molding (covers, casings,
cylinder, etc.) in the absence of modifying, the alloy containing 12% of silicon
has the structure consisting of rough structure eutectic and dark large needles of
silicon, reducing plastic properties of alloy.
Duralyumin of D1 brand (3,8-4,8% copper, 0,6% magnesium, 0,6%
manganese, to 0,7% silicon, the rest aluminum) possesses the sufficient
durability and plasticity. Sheets, bars, pipes, etc. are produced from it by means
of rolling or stamping. For obtaining these properties, duralumin is hardened in
water with 510ºС, and then exposed to aging at 18-20ºС within several days.
After aging, the structure of duralumin D1 consists of light grains of the
oversaturated firm solution representing solution of copper in aluminum. The
strengthening products received at aging, aren't visible under the microscope.
The bearing alloy babbit of B83 brand possesses high antifrictional
properties, is applied to filling of bearings of sliding. The structure of an alloy
consists of dark plastic basis α-phase, light firm particles of large cubic crystals
and small needles or stars of crystals.
Aluminum-metal of silver-white color, is characterized with a low density
of 2,7 g/cm ³, high conductivity, melting temperature 660ºС. Mechanical
properties of aluminum low therefore in pure form as the constructional material
is applied restrictedly.
Depending on the content of constant impurity we distinguish:
- aluminum of special purity of A999 brand (0,001% of impurity).
- aluminum of high purity - A935, A99, A97, A95 (0,005-0,5%).
- technical aluminum - A85, A8, A7, A5 (0,15-0,5%).
Among aluminum alloys, the greatest application was received by duralumin
and alpaxes.
Duralumin - are aluminum alloys with copper, manganese, magnesium and
silicon. Designated D2, D3, D4. The figure means serial number of an alloy.
Alpaxes – are aluminum alloys with silicon. Designated AL2, AL3, AL5. The
figure means serial number of an alloy
Magnesium and its alloys.
Magnesium - is the lightest (density of 1,74 g/cm ³) from technical non-
ferrous metals, silvery color, melting temperature 650ºС. At a temperature, a
little more melting temperature, easily ignites and burns with a bright white
flame.
Magnesium is among the most widespread elements in the nature. In the form
of connections, it is a part of mountain breeds magnesites, dolomite, carnallite
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and sea water (bischofite). Industrial production of magnesium is based on
electrolysis of fusions of the pure dehydrated salts.
The main advantage of magnesium as machine-building material is the low
density, technological effectiveness. However its corrosion resistance in damp
environments, acids, solutions of salts is lowest. Pure magnesium is practically
not used as a constructional material because of its insufficient corrosion
resistance. It is applied as an alloying additive to steel and cast iron and in
rocketry at creation of firm fuels.
Fig. 9.1. Microscopic structure of the technical titan of VTG-1-1. : a - after
annealing, b- after casting.
Fig. 9.2 – Transformation of mechanical property of the titan with weight of
nitrogen, oxygen and carbon.
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Fig. 9.3 – Transformation of mechanical property of the titan with plastically
deformations
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