Know the Steps of Extraction of Ores

Metallurgy is the branch of science which deals with the processing of metal from its ore . Elements are found in earth’s crust in the form of minerals. Naturally occurring substances in which metal exists in free form or in combined form is called mineral. Minerals are insoluble compounds.Mineral from which metal can be conveniently & economically extracted is called ore.All ore are minerals but all minerals are not ores.Small Impurities associated with ore are called matrix/gangue.

Extraction of Metals

Extractive metallurgy is a branch of metallurgy which deals with the extraction of metal from ore.There are various methods which are used to extricate metals from their ores. Depending on the kind of ore, the metal’s reactivity, and also the presence of impurities within the ore section will vary. Before metal can be mined, most metal ores must be delivered to Earth’s surface. This practice is known as mining. Metal extraction is divided into three steps in general. Some of them are as follows: 

1. Concentration of an ores
2. Isolation of metal from enriched ore
3. Refining or purification of impure metal

Step 1 – Concentration of an Ore

The purpose of concentration is to remove visible impurities from ore to make it useful for further extraction. As all of us know, minerals are observed in ores. For extraction of  minerals, we should first draw out the mineral’s ore. Impurities that are found in an ore and their elimination is important to extract metallic parts. In the wake of being mined from the earth, the metal consolidates assorted undesired debasements alongside sand, troublesome minerals, etc. The metals are focusing on the possibility of the kind of impurities and their percent rate to kill those unwanted substances. We can obtain a desired ore with an excessive percent of metallic with the aid of using it to do away with those impurities. The consideration of mineral, furthermore called metal enhancement, is the methodology of disposing of gangue trash from metal with the expectation to beautify the extent of metallic withinside the metal. To extract out engaged minerals containing a widely better percent of the metallic, stage one in metallurgy is to wipe out those undesired impurities from the metal. The impurities can be removed from ore either by physical processes such as Gravity separation, gravity separation, magnetic separation and froth flotation  or by chemical  processes such as leaching ,roasting and calcination. 

• Handpicking: Ore is first transformed into small pieces and sand stuck to is washed away by water.
• Hydraulic washing: this method is also called gravity separation. Specific gravities of an ore particle plays an important role in this method 
• Froth flotation method: The thought process of this framework is to remove gangue from sulphide metals. The metal is pounded and mixed with water to shape a suspension. Gatherers and Froth Stabilizers are brought to this. Gatherers like pine oils, unsaturated fats, and so forth further develop the steel a piece of the metal’s non-wettability, allowing it to shape a foam. Cresols, aniline, and different foam stabilisers keep up with the foam going. The oil greases up the steel, even as the water greases up the gangue. The foam is made through ceaselessly working up the suspension with oars and air. To get better the steel, the foamy steel is skimmed off the zenith and dried. This framework is utilised to focus on copper, lead, and zinc sulphide metals. The powdered mineral is situated in a tank total with water in this system. From that point onward, a little pine oil is applied. The sulphide mineral flotsam and jetsam are wetted with pine oil withinside the tank, even as the gangue garbage are wetted with water. From that point forward, the air is circled through the blend. This causes the water withinside the tank to foment, which allows the sulphide mineral trash to handle to the oil and up push to the floor as foam. Since gangue garbage is heavier, they settle to the most reduced of the water tank. The foam is isolated and used to extricate centred sulphide minerals.
• Chemical separation: This procedure, also known as leaching, involves using needed reagent ore particles dissolved in it white impurities settled down to the bottom. 
• Magnetic separation: To isolate the mineral and gangue, magnetic characteristics of both the metal or the gangue are utilised. The metal is first finely handled sooner than being passed on a transport line that disregards on a magnetic roller. The attractive metal remaining parts at the belt, simultaneously as the gangue slides off. By eliminating non-magnetic contaminations, this framework is used to focus on magnetic metals of iron including magnetite and chromite and manganese (pyrolusite). A magnetic separator is used in this system. An attractive separator is built from rollers and a cowhide based belt. One of the 2 rollers has a magnet implanted in it. The finely powdered magnetic metal is dropped over the moving belt at one outcome along these lines. The metal flotsam and jetsam is drawn in through the magnet and makes a different load from the non-magnetic impurities while the powdered mineral tumbles down from the moving belt at the far edge with a magnetic roller.

Step 2 – Reduction of Ores

In the Process of extraction of metal, concentrated ore moves for Reduction, and different metal ores different reduction methods are there, but first, one term is frequently used in the Reduction i.e. Smelting. Smelting : Smelting means slag formation or Carbon Reduction. Cu2O is self-reduced by Cu2S and forms Cu, and it is known as blister copper due to the removal of SO2 .Highly reactive metals are reduced by electrolysis by their molten salts as we learn in metal reactivity series. Aluminium is a highly reactive metal so it is reduced by electrolysis. For s-block or p-block element electrolysis takes place with chloride generally, Bromide & iodied in used due to covalent in nature. In case of fluoride, gas release & its highly corrosive in nature

Step 3-Refining/Purification

Reduction of ore gives metal by removing some non-volatile impurities but some of the impurities are remaining so that the final step is refining/purification of metal. There are various methods for refining metals. 

Distillation

 Process ⇒ Heating of metal just above its boiling point so impurities remain in solid state 

Used for ⇒ Zn, Cd, Hg 

Concept ⇒ When boiling point of pure metal less than B.P. of impurities. 

Function ⇒ Zn, Cd, Hg used due to d10s2 full filled orbital, d-d metal-metal bonding not possible so weak attraction is present So boiling point decreases.

Liquation

Process ⇒ impure metal heated on sloped surface furnace, pure metal obtained in liquid state, impurities remain in solid state. 

Used for Sn, Pb, Bi 

Concept ⇒ Melting point Pure metal is less than impurities.

 Function ⇒ Sn, Pb & Bi heavy p-block metal in this metal-metal bonding decreases, size increases and metallic character decreases.

Conclusions

Metallurgy is a branch of science concerned with the drawing out metals from naturally occurring ores. A range of methods are used to extricate metals from their ores. The first step of concentration of an ore is metallurgy, which is to eliminate these unwanted impurities from the ore in order to create a concentrated ore with a greater metal content. Depending on the type of ore, the metal’s reactivity, and the presence of impurities in the ore phase can vary.