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Definition of Metallurgy | Methods Used in Metallurgy

Definition of Metallurgy | Methods Used in Metallurgy

Metallurgy is the technology and science to extract metals from their ores economically, metallurgy is the art and science of separating or extracting metals from their ores and modifying the metals for use. Metallurgy is two types chemical metallurgy and physical metallurgy.

Metallurgy Concentration Methods

Methods for removing impurities called concentration, there are four methods of concentration (i) Gravity separation (ii) Magnetic separation (iii) Froth floatation (iv) Leaching

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(i) Gravity Separation:- This method is used when there is a difference in density of the ores and impurities. Commonly used for removing Si impurities. Gravity separation is also called hydraulic washing or lavation.

Gravity Separation

(ii) Magnetic Separation:- This method is used when ores and impurities have differences in magnetic properties.

Magnetic Separation

(iii) Froth Floatation:- This method is mainly used for S¯² ores MS¯² + impurities. The principal of the froth floatation method is the wetting property of ores and impurities.

Process of Froth F to Metallurgy 

In a large tank (oil + water + ore +collector + stabilizer) are mixed and compressed air is passed, air bubbles are formed which attach mineral particles on the surface and carried them as froth. In form of collector generally, we use- Pine oil and sodium ethyl xanthitane, and aniline and cresol work as froths stabilizers.

(iv) Leaching process:- X + Y are both water-insoluble so cannot separate and add leaching agent Z, which leaches X from a mixture of (X+Y), XZ+Y now they can separate each other.

                X + Y    ⟶+Z⟶ XZ +Y

Extraction of aluminum from bauxite. What are the steps involved in the extraction of aluminum from bauxite? 

The major impurity is Fe2O3 (Rust). The color of Fe2O3 is red so-called red bauxite. Bayers used NaOH and patent to his so-called buyer's process. Halls used Na2CO3 and patent to his so-called halls process.

       Leaching   NaOH

                   (Water-soluble)

NaAlO2 + Fe2O3 (Water-insoluble)

                  ↓  filtration

  NaAlO2 (sodium meta aluminate)

                Co2 (Acidification)

        Al2O3 (Water Insoluble) 

             Na3AlF6 and CaF6 (Electrolytic Reduction )

         Al ( impure)

            Electrolytic refining

        Al ( Pure)

Conversion of Ores into Metal Oxide

All concentrated ores are not easily reduced so concentrated ores must be converted into a form that is suitable for a reduction. Usually, sulfides and other ores are converted into oxides by following two processes. (i) Calcination (ii) Roasting

(i) Calcination:- Calcination is the heating of the ores in absence of (O2). It is commonly done for oxy-ores like carbonate and sulfate.

    MCo2  heat⟶ Mo + Co2 

   Calamine (ZnCo3) heat → ZnO + Co2↑

   Anglesite (Pb So4) heat ⟶ PbO + So3

(ii) Roasting:- Roasting is heating ores in presence of air. It is commonly done for non-oxy ores like sulfate ore. By roasting, sulfate ores can be converted to more reactive oxide for some ores partial roasting is done which is followed by self-reduction of ores.

Reduction of Metal-Oxide into Metal

(i) Carbon Reduction:- MO ⟶ M + CO/ CO2, CO2 is a good reducing agent at low temp. so in the furnace at the upper level of a blast furnace. CO is a good reducing agent at a high temp. so it is at a lower position in the blast furnace. Exp. Fe, Sn, Pb, Zn.

(ii) Electrolytic Reducing:- This method is used for recovery of oxides of reactive metal ( s-block and aluminum) 

M .O  ⟶ M

Al2O3 ( HALL-HEROULT CELL)

It is difficult to reduce the metals that why for reactive metals electrolytic reduction.

(iii) Self Reduction or Auto reduction:- It is applied for (Cu, Hg, Pb) after partial roasting of their sulfide.

Cu2S   +   Cu2O (under no air)  ⟶  Cu↓  +  SO2 

                                                        Blister copper 

(iv) Thermite Reduction:- The reduction is used in thermite welding (welding of railway track)

MO + Al   ⟶ M + Al2O3 + Heat, Metal must be less reactive than aluminum eg. Fe, Mn, Cr, Ti, 

(v) Hydrometallurgy reduction:- HMR is mainly used for the recovery of Silver and Gold.

Na [Ag (CN)2] + Zn  ⟶  Na2 [Zn (CN)2] + Ag

(vi) Thermal reduction:- Used for oxide of Ag and Hg (Due to +Ve S.R.P)

Refining and Purification of Obtained Metal

This method is used for ores refining and purifications.

(i) Liquation:- Liquation processes are used when metal and impurity have a different boiling point.

(ii) Cupellation:- Cupel is made up of bone ash and cement mixture. Cupel is so strong and even can tolerate 4000 °C temperature. This is a method used to remove the impurities Pb from precious metals Au and Ag.

Cupellation

(iii) Distillation:- Distillation is used for the metal having a low boiling point and melting point. eg. Zn, Hg.

Distillation method metal refining

(iv) Polling:- This method is used when the main impurities with metal are its own oxide. Metal separated from metal oxide by a reduction for reduction we will use a reducing agent.

        CH4 + MO ⟶ CO/CO2 + H2O + M

Polling refining

(v) Electro Refining (All types of metals):- This method is used for ultra purification of metals, Anode MUD generally contains less basic metals like silver and gold which can be recovered from the meet of cost of refining.

Electro Refining (All types of metals)

(vi) Zone Refining:- This method is used for semiconductor Si, Ge. This method also gives ultra-pure metals. Impurities are more soluble in a zone of higher temperatures.

Zone Refining

(vii) Vapour phase refining:- In this method the is converted into its volatile compounds and collected elsewhere, it is then decomposed to give pure metal. Two requirements are (a) Metal Should form a voltaic compound. (b) voltaic compounds should be easily decomposed. 

Metallic Bonding Examples

Metallic bonding occurs when positively charged metal ions are held together by a sea of ​​delocalized electrons. This type of bonding is characteristic of metals and is responsible for many of their properties such as high thermal and electrical conductivity, ductility and malleability.

1. Copper (Cu): Copper is a soft, malleable and ductile metal that is a good conductor of heat and electricity. It has a face-centred cubic crystal structure, and its atoms are held together by metallic bonds.

2. Iron (Fe): Iron is a hard, strong, and magnetic metal that is essential for many industrial applications. It has a body-centred cubic crystal structure, and its atoms are held together by metallic bonds.

3. Gold (Au): Gold is a highly valuable and sought-after metal known for its beauty, rarity, and durability. It has a face-centred cubic crystal structure, and its atoms are held together by metallic bonds.

>Intramolecular and Intermolecular forces

>Specific Gravity Calculate

>Grain size analysis | Sieve analysis | Laboratory test sieves

   

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