METALLURGY AND ITS PROSPECTS

Welcome To Our Presentation

Name ID

MD. Ubidullah Khokan 19-003

MD. Ashadul Islam 19-141

MD. Mahedy Hasan 19-272

Sudev Chakma 19-251

Zubayer Ahmed 19-257

Bijoy Dripto Acharjya 19-261

Submitted To-

Dr. Md. Zahangir Alam

Associate Professor

Department of Applied Chemistry & Chemical Engineering

University of Dhaka

Submitted By-

MD. ASHADUL ISLAM

19-141

METALLURGY

art and science of extracting metals from their ores and modifying the metals for use.

Study of the chemical, physical, and atomic properties and structures of metals and the principles whereby metals are combined to form alloys.

HISTORY OF METALLURGY

A magic materialThe first known metal was gold. Gold is bright, incorruptible, malleable,

and appears in pure form in the beds of streams.

The earliest surviving gold jewelry is from Egypt in about 3000 BC.

HISTORY OF METALLURGY

The age of copper: from 7000 BCFrom about 7000 BC a few neolithic

communities begin hammering copper into crude knives and sickles.

azurite and malachite, two ores of copper were found.

two significant steps in the development of metallurgy:

- the casting of metal, by pouring it into prepared moulds

- the smelting of mineral ores to extract metal.

HISTORY OF METALLURGY

The age of bronze: from 2800 BCThe cast alloy of copper and tin is bronzeThe technology of bronze is first developed

in the Middle East

The age of iron: from 1500 BCA few iron objects dating from before 2000

BC have been found (beads, a ring, some blades), but it is not until about 1500 BC that the working of iron is done anywhere on a regular basis.

The Hittites are the first people to work iron, in Anatolia from about 1500 BC

HISTORY OF METALLURGY

The discovery of steel: 11th century BCBy the 11th century BC it has been discovered that iron can be much

improved. If it is reheated in a furnace with charcoal (containing carbon), some of the carbon is transferred to the iron.

A new material- steel is produced

Cast iron in the east: 513 BCThe melting point of iron (1528°C) is too high for primitive furnaces.The Chinese develop a furnace hot enough to melt iron, enabling them to

produce the world's first cast iron

HISTORY OF METALLURGY

Ironmasters of Coalbrookdale: 18th centuryIn 1709 Abraham Darby, an ironmaster

with a furnace at Coalbrookdale on the river Severn, discovers that coke can be used instead of charcoal for the smelting of pig iron.

Iron bridge: 1779in 1779 the world's first iron bridge,

with a single span of over 100 feet, is created over the Severn just downstream from Coalbrookdale.

HISTORY OF METALLURGY

Pudding and rolling: 1783-1784Henry Cort invented a furnace which shakes the molten iron so that air

mingles with it.  The technique which becomes known as pudding. Oxygen combines with carbon in the metallic compound, leaving almost pure iron.

In the previous year he invented machine for drawing out red-hot lumps of purified metal between grooved rollers, turning them into manageable bar. His device is the origin of the rolling mills.

HISTORY OF METALLURGY

 The 19th centuryThe large-scale production of

cheap steel. The development of the open-hearth

furnace by William and Friedrich Siemens in Britain and by Pierre and Émile Martin in France.

The separation from their ores, on a substantial scale, of aluminum and magnesium.

Development of electrolytic cell for producing cheaper sodium in 1886.

HISTORY OF METALLURGY

The 20th century the introduction of fusion weldingThe first practical oxyacetylene torch was

produced in 1901.Striking an arc from a coated metal electrode,

which melts into the join, was introduced in 1910. In extractive metallurgy, the application of

chemical thermodynamics, kinetics, and chemical engineering are introduced.

 In physical metallurgy, the study of relationships between macrostructure, atomic structure and physical and mechanical properties are developed.

MD. UBIDULLAH KHOKAN

19-003

EXTRACTIVE METALLURGY

Extractive metallurgy is the art of obtaining valuable metals from an ore or metallic concentrate and refining the initial products into a purer form.

Metals can be found on the earth in several chemical forms such as natives (gold, copper), oxides, sulphides, sulphates, carbonates, nitrates, and others.

The compound must be converted into a type that can be more readily treated. Common practice is to convert metallic sulfides to oxides, sulfates, or chlorides; oxides to sulfates or chlorides; and carbonates to oxides.

EXTRACTIVE METALLURGY

Extractive metallurgy involves-

mineral processing,

pyrometallurgy,

hydrometallurgy,

electrometallurgy.

EXTRACTIVE METALLURGY

Mineral processingMineral processing involves crushing,

grinding, and concentration.

Pyrometallurgy Pyrometallurgy involves the treatment

of ores at high temperature to convert ore minerals to raw metals, or intermediate compounds for further refining.

EXTRACTIVE METALLURGY

The processes of Pyrometallurgy are-Roasting- in which compounds are converted at temperatures just below

their melting points.smelting- All the constituents of an ore or concentrate are completely

melted and separated into two liquid layers, one containing the valuable metals and the other the waste rock.

Refining- The final procedure for removing the last small amounts of impurities left after the major extraction steps have been completed.

EXTRACTIVE METALLURGY

HydrometallurgyHydrometallurgy involves the use of aqueous solutions to extract metals

or compounds from their ores.

The processes are- Conversion

Leaching

Recovery

EXTRACTIVE METALLURGY

Conversion- Because not all ores and concentrates are found naturally in a form that

is satisfactory for leaching, they must often be subjected to preliminary operations. For example, sulfide ores, which are relatively insoluble in sulfuric acid, can be converted to quite soluble forms by oxidizing or sulfatizing roasts.

A second popular treatment for converting sulfides is pressure oxidation, in which the sulfides are oxidized to a porous structure.

EXTRACTIVE METALLURGY

LeachingDissolution of the valuable metals into the aqueous solution.Oxides are leached with a sulfuric acid or sodium carbonate solvent. sulfates can be leached with water or sulfuric acid.  Ammonium hydroxide [NH4OH] is used for native ores, carbonates, and

sulfides, and sodium hydroxide [NaOH] is used for oxides. Cyanide solutions are a solvent for the precious metals, while a sodium chloride solution dissolves some chlorides.

Two methods of leaching:

simple leaching

pressure leaching

EXTRACTIVE METALLURGY

Recoverythe  solution from leaching operations is treated in a variety of ways to

precipitate the dissolved metal values and recover them in solid form.

These include-electrolytic deposition-  Insoluble anodes, and cathodes are inserted into

a tank containing leach solution. As current is passed, the solution dissociates, and metal ions deposit at the cathode. This common method is used for copper, zinc, nickel, and cobalt.

EXTRACTIVE METALLURGY

Recovery continue….chemical precipitation-  a displacement reaction takes place in which a

more active metal replaces a less active metal in solution. For example, in copper cementation iron replaces copper ions in solution.

changing the acidity of a solution is a common method of precipitation.

BIJOY DRIPTO ACHARJYA

19-261

PHYSICAL METALLURGY

Physical metallurgy is the science of making useful products out of metals.

Metal parts can be made in a variety of ways, depending on the shape, properties, and cost desired in the finished product.

 The cost of a finished part is often determined more by its ease of manufacture than by the cost of the material.

 Usually a metal part has the same properties throughout.

PHYSICAL METALLURGY

Structures and properties of metals

Metallic crystal structures-Metals are used in engineering structures (e.g., automobiles, bridges, pressure

vessels) because, in contrast to glass or ceramic, they can undergo appreciable plastic deformation before breaking.

This plasticity stems from the crystalline structure of metal and the nondirectional nature of the bond between the atoms.

 In the most ductile metals, atoms are arranged in a close-packed manner.aluminum, copper, nickel, gamma iron, gold, and silver are  face-centred cubic

structured.alpha iron, tungsten, chromium, and beta titanium are  body-centred cubic

structured.

PHYSICAL METALLURGY

Physical Property

Good electrical conductors and heat

conductors.

Dense – Most metals have high density.

Malleable - can be beaten into thin

sheets.

Ductile - can be stretched into wire.

Solid at room temperature (except Hg).

Sonorous – Metals make a ringing

sound when they are struck.

Possess metallic luster.

Have high melting and boiling point.Opaque as thin sheet.

PHYSICAL METALLURGY

Chemical Property

Usually have 1-3 electrons in their outer shell.

Lose their valence electrons easily.

Almost any metal will oxidize in air, the only exception is gold.

Are good reducing agents.

Have lower electronegativities.

PHYSICAL METALLURGY

AlloyAlmost all metals are used as alloy.Alloy is the solid solution of tow or more metals.Alloys have properties superior to pure metal.

PHYSICAL METALLURGY

Reasons for making AlloyTo improve the strength and hardness of metals.To improve the appearance of metals.To improve the resistance of metal against corrosion and rusting. To lower the melting point of metal.

ZUBAYER AHMED

19-257

PHYSICAL METALLURGY

CastingCasting consists of  pouring molten

metal into a mold, where it solidifies into the shape of the mold.

The process was well established in the Bronze Age (beginning. 3000 BC)

It is particularly valuable for the economical production of complex shapes, ranging from mass-produced parts for automobiles to production of statues, jewelry, or massive machinery.

PHYSICAL METALLURGY

Casting ProcessSand-casting Sand-casting is widely used for making cast-iron and steel parts of

medium to large sizesand combined with a binder such as water and clay is packed around a

pattern to form the mold.

Metal molds molds are made from metal.

PHYSICAL METALLURGY

Casting Process Continued….Investment castingIn investment casting a mold is made by drying a refractory slurry on a

pattern made of wax or plastic. A series of layers is applied and dried to make a ceramic shell, and the

pattern is then melted or burned out to provide the mold.This process allows the mass production of parts with more complex shapes

and finer surface

Centrifugal castingCentrifugal casting forces the metal into a mold by spinning it.It is used for the casting of small precious-metal objects

PHYSICAL METALLURGY

MetalWorkingMetalworking is the process of working with metals to create individual

parts, assemblies, or large-scale structures.- these can be divided into five broad groups:

1) Rolling Rolling is a metal forming process in which metal stock is passed through

one or more pairs of rolls to reduce the thickness and to make the thickness uniform.

- More than 90 percent of the aluminum, steel, and copper produced is rolled at least once in the course of production.

PHYSICAL METALLURGY

2) ExtrusionExtrusion is the process by which long straight metal parts can be produced.The cross-sections that can be produced vary from solid round, rectangular, to L

shapes, T shapes.Extrusion is done by squeezing metal in a closed cavity through a tool, known as

a die using either a mechanical or hydraulic press.

3) DrawingDrawing consists of pulling metal through a die.

4) sheet metal forming

5) ForgingForging is the shaping of a piece of metal by pushing with open or closed dies.

MD. MAHEDY HASAN

19-272

POWDER METALLURGY

Powder metallurgy (P/M) consists of making solid parts out of metal powders and and using them to make finished or semi-finished products.

Used when• melting point is too high .• reaction occurs at melting .• too hard to machine.• very large quantity.

POWDER METALLURGY

Powder Metallurgy Processes -Powder productionBlending or mixingPowder compactionSinteringFinishing Operations

POWDER METALLURGY

Powder productionThe most common method of producing

metal powders is atomization of a liquid.

Here a stream of molten metal is broken up into small droplets with a jet of water, air, or inert gas such as nitrogen or argon.

Different shapes produced Will affect compaction process significantly

POWDER METALLURGY

Blending or mixingBlending means mixing powder of the same chemical composition but different

sizes.Mixing means combining powders of different chemistries.Except for powders, some other ingredients are usually added:

Lubricants: to reduce the particles-die friction

Binders: to achieve enough strength before sintering

Deflocculants: to improve the flow characteristics during feedingElemental or pre-alloyed metal powders are first mixed with lubricants or other

alloy to produce a homogeneous mixture of ingredients Blending and mixing are accomplished by mechanical means.

SUDEV CHAKMA

19-251

POWDER METALLURGY

Powder compactionPressing processBlended powders are pressed in dies under high pressure to form them

into the required shape. Produces a “Green” compact

Size and shape of finished part (almost)Not as strong as finished part – handling concern

POWDER METALLURGY

Powder compaction Pressure: Cold Isostatic PressingHot Isostatic PressingHigh Energy Rate TechniquesVibratory CompactionContinuous CompactionForging or Extrusion

POWDER METALLURGY

SinteringGreen compacts are heated in a controlled-atmosphere furnace to allow

packed metal powders to bond togetherTransforms compacted mechanical bonds to much stronger metal bonds.

POWDER METALLURGY

Finishing Operationsto improve properties, finishing processes are needed:

• Cold restriking, resintering, and heat treatment.• Impregnation of heated oil. • Infiltration with metal (e.g., Cu for ferrous parts).• Machining to tighter tolerance.

Plating, Painting

POWDER METALLURGY

APPLICATION POWDER METALLURGY

Electrical Contact materialsSliding Electrical Contacts Heavy-duty Friction materialsSelf-Lubricating Porous bearingsCarbide, Alumina, Diamond cutting tools Structural partsCermetsHard and Wear Resistant ToolsRefractory Material Products

THESE COMPONENTS ARE USED IN AIR & SPACE CRAFTS, HEAVY MACHINERY, COMPUTERS, AUTOMOBILES, etc…

APPLICATION POWDER METALLURGY

Anti-friction products Friction productsVery Hard MagnetsVery Soft Magnetsfilters