What Is Extraction Of Crude Metal From Concentrated Ore Steps Methods and Chemical Reactions Explained
Learn the Extraction of Crude Metal from Concentrated Ore
The discovery of metals and its various innovative uses have paved the way to the modern civilization we are currently living in. Almost everything we use in our daily lives is made of metal. From medical equipment to agricultural infrastructure, clothing manufacturing to residential constructions, you will find different types of metals used for various purposes. This is why metallurgy has been added as a part of the chemistry syllabus in the advanced classes. Learning how to extract metals from ores using the inorganic properties of the constituents is very important.
The concept page of Vedantu has been prepared by the top mentors so that students can understand these topics properly. On this concept page, students will learn how the extraction of crude metal from concentrated ore is done in different ways. Follow how the experts have used the simplest language to make these concepts easy to understand for students. Find out the best ways to tackle your queries by using this concept page as a reference.
What is the Extraction of Metals?
Every ore is extracted from the mines with the sole purpose of collecting a particular metal. The ore is mined and then sent to the refining chambers. There are several processes involved in concentrating the ore of a metal. This concentrating part starts with pulverization of the big ore chunks in the jaw crushes or ball mills.
After completely reducing the grain size of the ore, it is then sent to the concentrating segment where the amount of ore containing the metal is increased by removing impurities as much as possible. The processes involved in this part of the metal extraction process are:
Hydrolytic Method
Water is sprayed with a force on the pulverized ore grains. The metal-containing grains settle down on the grooved inclined table and the impurities wash down.
Magnetic Separation
This is one of the easier metal ore concentration processes used for ferromagnetic substances. The wheels running a conveyor belt are magnetic. They keep the magnetic ore particles stuck to the belt and the rest of the impurities fall down.
Froth Floatation
This is a process of concentrating the ore where a dual medium of oil and water is used. Compressed air is sent in the mixture to form frothing in the oil medium. The ore particles containing the metal form froths that are collected on the top of the oil medium. The impurities that are unable to get dissolved either in oil or water settle down.
After these processes, the concentrated ore is then subjected to another purification method. This is where the metal is then separated from the ore by means of heating. It is either done in the presence or absence of air. To remove it from the concentrated ore, the original state has to be converted into an oxide first. This is done by following the two processes related to the extraction of crude metal from concentrated ore mentioned below.
Calcination
This is a process where the concentrated ore is subjected to immense heat in a very limited supply of air or oxygen. It is sometimes done in the absence of oxygen. The hydrated oxides lose all the water molecules associated leaving the oxide of the metal behind. In fact, it is also done to break down the carbonated salts of different elements. For instance, it is done to remove the associated water molecules of ferric oxide. It is also used to break and remove the carbonate functional group from the salts of calcium and magnesium. When you will study this process of extraction of crude metal from the ore with the help of examples on this concept page, it will become a lot easier to understand.
Roasting
Roasting, on the other hand, is heating the concentrated ore to extreme temperature in the presence of oxygen so that the sulphides of the ores can be oxidized to form metal oxides. The superheated oxygen in the air removes the sulphide group in the metal ore in the form of sulphur oxides and leaves the oxide of metals behind. This extraction of crude metal from the ore is done for extracting copper from copper sulphides, lead from lead sulphides and zinc from zinc sulphides.
After this step, the oxide of the metals is then reduced by heating them in the presence of carbon. Carbon reduces the oxides to pure metals as it takes away oxygen to form carbon oxides.
FAQs on Extraction Of Crude Metal From Concentrated Ore in Metallurgy
1. What is extraction of crude metal from concentrated ore?
The extraction of crude metal from concentrated ore is the process of obtaining an impure form of metal by chemically reducing the concentrated ore. It is the main step in metallurgy after concentration of ore.
- The concentrated ore is converted into metal by roasting, calcination, or direct reduction.
- The metal obtained at this stage is called crude metal because it contains impurities.
- Further purification is done by refining processes such as electrolytic refining.
2. What are the main steps involved in extraction of metals from concentrated ore?
The main steps in extraction of metals from concentrated ore are conversion to oxide and reduction to metal. These steps convert the concentrated ore into crude metal.
- Roasting: Heating sulphide ore in excess air.
Example: 2ZnS(s) + 3O2(g) → 2ZnO(s) + 2SO2(g) - Calcination: Heating carbonate ore in limited or no air.
Example: ZnCO3(s) → ZnO(s) + CO2(g) - Reduction: Metal oxide is reduced using a reducing agent like carbon.
Example: ZnO(s) + C(s) → Zn(s) + CO(g)
3. Why is roasting carried out in the extraction of sulphide ores?
Roasting is carried out to convert sulphide ores into metal oxides by heating them in excess air. This makes the ore easier to reduce to metal.
- Sulphur is removed as SO2(g).
- The resulting metal oxide can be reduced by carbon or other reducing agents.
- Example: 2PbS(s) + 3O2(g) → 2PbO(s) + 2SO2(g)
4. What is calcination in metallurgy?
Calcination is the process of heating a carbonate or hydrated ore in the absence or limited supply of air to convert it into oxide. It removes volatile impurities.
- Moisture and carbon dioxide are driven off.
- Used mainly for carbonate ores.
- Example: CaCO3(s) → CaO(s) + CO2(g)
5. How is metal oxide reduced to crude metal?
Metal oxide is reduced to crude metal by using a reducing agent such as carbon, carbon monoxide, or aluminium. The reducing agent removes oxygen from the oxide.
- For moderately reactive metals, carbon is used.
Example: Fe2O3(s) + 3CO(g) → 2Fe(s) + 3CO2(g) - For highly reactive metals, electrolysis is used.
Example: Electrolysis of molten Al2O3 to obtain aluminium.
6. What is the role of carbon in extraction of metals?
Carbon acts as a reducing agent in the extraction of metals by removing oxygen from metal oxides. It converts the oxide into free metal.
- Carbon may form CO or CO2 during reduction.
- Used for metals below carbon in the reactivity series.
- Example: ZnO(s) + C(s) → Zn(s) + CO(g)
7. What is the difference between roasting and calcination?
The main difference is that roasting is heating sulphide ores in excess air, while calcination is heating carbonate ores in limited or no air.
- Roasting: Converts sulphides to oxides and releases SO2.
- Calcination: Converts carbonates to oxides and releases CO2.
- Roasting requires oxygen; calcination does not require excess oxygen.
8. How does the reactivity series affect extraction of metals?
The reactivity series determines the method used for extraction of metals from their ores. More reactive metals require stronger methods.
- Highly reactive metals (e.g., K, Na, Al) → Extracted by electrolysis.
- Moderately reactive metals (e.g., Fe, Zn) → Extracted by reduction with carbon.
- Low reactive metals (e.g., Hg, Cu) → Often obtained by simple heating or self-reduction.
9. What is self-reduction in metallurgy?
Self-reduction is a process in which a sulphide ore is partially oxidized and then the oxide reacts with the remaining sulphide to produce metal. No external reducing agent is required.
- Occurs during roasting of some sulphide ores.
- Example in copper extraction:
2Cu2O(s) + Cu2S(s) → 6Cu(s) + SO2(g)
10. Why is crude metal further refined after extraction?
Crude metal is further refined because it contains impurities that affect its physical and chemical properties. Refining increases purity and improves usability.
- Impurities may reduce strength, conductivity, or corrosion resistance.
- Common refining methods include electrolytic refining, distillation, and zone refining.
- Example: In electrolytic refining of copper, impure Cu acts as anode and pure Cu is deposited at cathode.
