The extraction of pure metals from their ores and further modify them for commercial usage is called metallurgy. It tells us about how science is applied to the production of metals, also their physical and chemical behavior.
Metallurgy is highly specialized branch. Almost, all the metal producing industries employ metallurgists in the bulk demand comes from the Steel making industry. They play a very crucial role in our industrial sector as like they are the backbone of our automobiles, ships, modern aircraft etc. It is said that our economic and technical progress in the 21st century will depend in large part on the further advances in the metal and mineral technology.
#STEPS INVOLVING IN EXTRACTION OF METAL FROM ORES ARE :
1. Crushing and Grinding of Ores- Jaw Crushers and Ball Mills are used to crush ores into fine powder this process is called as Pulverization.
2. Concentration of Ore- After pulverization, based on the type of impurities and their percentage proportions, ores are concentrated. This concentration methods are carried out by Centrifugation, Froth Flotation and Magnetic Separation.
- Centrifugation: In this method the fine powder is placed inside the grooves of the moving table and it moved rapidly. Then,with the help of water the ore particles of higher density settles down and the impurity particles of lesser density are separated.
- Froth Flotation- This method is carried out for the sulphide ores like copper, zinc, lead because the ore particles are lighter as compared to the impurities present in them. Pulverized ore solution is taken in the large tank containing water, frothers and surfactants or collectors.
Frothers helps to make forth(foam) which is collected on the surface of water. Pine oil and Camphor oil are used to make froth. Froth stabilizers are also added to increase the stability of froth. Aniline and Cresols are widely used. Once the froth is foamed we have to add the surfactants or collectors it helps in the absorption of the ore particles on the surface of froth. Examples Sodium Ethyl Xanthate, Sodium Lauryl Sulphate. Now ore becomes water repellant and collected on the surface of water ,the impurities settles down and the ore is separated.
- Magnetic Separation- This method is carried out when the ore particles are magnetic and the impurities are non-magnetic. Pulverized ore is dropped on the conveyor belt that has two strong electromagnetic rollers. The magnetic particles are attracted to the rollers and collected near to it and non-magnetic material is collected separately.
3. Conversion of Ores to Oxides- Methods like Calcination, roasting, smelting are used to the concentrated ore into metal oxide.
- Calcination- It is the process of heating concentrated ore in absence of oxygen. Hydroxide ore and carbonate ore are usually carried out with this process. Examples like Calcite(CaCo3) with the formation of calcium oxide(CaO) and the liberation of Carbon dioxide(Co2). Magnesium Hydroxide(Mg(OH)2) with the formation of magnesium oxide (MgO) and liberation of H2O.
- Roasting- It is the process of heating concentrated ore in the presence of oxygen. Sulfide ores are used. Examples like Zinc Sulfide(ZnS) with the formation of Zinc oxide(ZnO) and liberates Sulfur dioxide(So2).
- Smelting- Some ores are the chemical compound of metal with the other metals like oxygen, sulfur which are extracted by smelting. In this process the ore is mixed with flux( it is the cleaning agent), fuel and heated strongly in the blast furnace.
For example, iron is extracted from the hematite ore through the process of smelting. In this coke is used as fuel and calcium carbonate is used as flux. Now, burning of fuel produces carbon monoxide. It further reduced the hematite ore to iron. Here, calcium carbonate is decomposed and produces calcium oxide which further react with impurities and produces slag which is removed.
Chemical Reaction of extracting Iron from the Hematite Ore:
2C + O2 = 2CO
Fe2O3 + 3CO = 2Fe + 3CO2
CaCO3 = CaO + CO2
CaO + SiO2 = CaSiO3
TYPES OF METALLURGY –
- Physical metallurgy:
It is the science of making metals into useful products. It generally focuses on the physical properties and structure of the metals and alloys. Metal parts can be made in a variety of ways, it generally depends upon their physical properties like shape, size and also electrical, magnetic and chemical nature. These properties help in the wide variety of ways to foam metals and to create a competition among different forming metals.
- Mechanical metallurgy:
It is the most diverse and versatile engineering field. This field is the combination of engineering physics and mathematics principles to design, analyze, manufacture mechanical systems. This field requires the knowledge of core areas including mechanics, dynamics, thermodynamics, material science, structural analysis and electricity. They can design everything like from new batteries, medical devices, computer devices, industrial equipment, machinery and also aircraft, watercraft, robotics, weapons etc.
- Extractive metallurgy:
This branch processes the methods of extraction of metals from their natural mineral deposits which is called as ore into the purer foam. This field generally categorized into various groups based on the different processes to extract the metal. This includes – Mineral processing- It is also known as ore dressing which includes breaking down of the ore to the requires sizes, followed by Crushing, Grinding and Sieving. Separation processes take advantage from the physical properties that includes density, particle size and shape, electrical and chemical properties, and surface properties. These methods involve magnetic separation, froth flotation and leaching etc.
- Hydro metallurgy– It involves the extraction of metals by using aqueous solutions. Most common method used in the hydro metallurgy is leaching. After the extraction of valuable metal from the ore solids, it undergoes various processes of purification and concentration. This may include precipitation, distillation, absorption and solvent extraction.
- Pyro metallurgy-
In this method the extraction and purification of metals involves high temperature processes where chemical reactions takes place among solid, liquid and molten materials. Commonly, gases and solids are carried out by calcining and roasting operations and molten materials are carried out by smelting operations.
This method uses electrical energy to produce metal by electrolysis that place in the foam of the electrolytic cell. Most common processes are electrowinning and electro-refining.
WHO IS METALLURGIST?
Metallurgist are the metal engineers and also called as the material science engineers. They study the science of the metals and do various types of researchers. They are specialized in the metals like iron, aluminum, steel, copper etc and converting them into products which are useful for humans. They work in the Iron and Steel industrial areas and research laboratories. Metal extractors like Tata Steel, Steel Authority of India (SAIL), Hindustan Copper Limited, Hindalco Industries Limited and Jindal Steels are the leading companies in India.
Metallurgical engineering is the wide field and offers a lot of opportunities to young youth candidates. They work in the metal extraction companies. They can also opt teaching profession in the universities and colleges. Other jobs profiles available for the metallurgical engineers like Researcher, Metallurgist, Wielding engineer, Plant Equipment Engineer, Ballistics Engineer, Metallurgical R&D Lab Technician, Vendor Development Engineer etc. In India various colleges offers 4- year bachelor’s degree (B-Tech) that focuses on the metallurgical engineering. Salary depends upon the education and experience of the metallurgical engineer. Average starting salary with a bachelor’s degree is $50,982. Other benefits are paid holidays and vacations, health insurance, and pension plans.