Q1. How is a mineral or earthy substance extracted from ore through the process of smelting?
a) By crushing and grinding the ore into fine particles
b) By heating the ore to high temperatures in the presence of reducing agents
c) By dissolving the ore in a solvent to separate the desired substance
d) By subjecting the ore to magnetic separation techniques
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Correct Answer: b) By heating the ore to high temperatures in the presence of reducing agents
Explanation: Smelting is a metallurgical process used to extract minerals or earthy substances from ore. It involves heating the ore to high temperatures in the presence of reducing agents, such as carbon or coke. This process causes the desired metal or mineral to separate from the ore and form a molten mass, which can then be further processed and refined to obtain the final product. Smelting is commonly used in the extraction of metals like iron, copper, lead, and zinc from their respective ores.
Q2. What is the primary purpose of crushing and grinding ore in the extraction process?
a) To increase the volume of the ore
b) To reduce the size of the ore particles
c) To dissolve the ore in a solvent
d) To separate the impurities from the ore
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Correct Answer: b) To reduce the size of the ore particles
Explanation: Crushing and grinding are essential steps in the extraction of minerals or earthy substances from ore. These processes involve breaking down the ore into smaller particles to increase its surface area, facilitating subsequent chemical or physical separation techniques. By reducing the size of the ore particles, crushing and grinding enhance the efficiency of processes such as leaching, flotation, and smelting, ultimately leading to the extraction of the desired substance.
Q3. Which method involves the use of water to separate minerals from the gangue in the extraction of ore?
a) Smelting
b) Leaching
c) Froth flotation
d) Magnetic separation
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Correct Answer: c) Froth flotation
Explanation: Froth flotation is a method used to separate minerals from the gangue (unwanted material) in the extraction of ore. In this process, finely ground ore is mixed with water and flotation agents, such as surfactants or collectors. Air bubbles are then introduced into the mixture, causing the hydrophobic minerals to attach to the bubbles and rise to the surface as a froth. The froth is skimmed off, carrying the valuable minerals, while the gangue sinks to the bottom. Froth flotation is widely used in the mining industry for the extraction of various metals and minerals.
Q4. How is ore extracted from the Earth’s crust in open-pit mining?
a) By drilling vertical shafts underground
b) By digging horizontal tunnels underground
c) By excavating large open pits or quarries
d) By hydraulic fracturing of rock formations
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Correct Answer: c) By excavating large open pits or quarries
Explanation: Open-pit mining is a surface mining technique used to extract ore deposits from the Earth’s crust. In this method, large open pits or quarries are excavated to access the ore body, which lies near the surface. Heavy machinery, such as excavators, haul trucks, and bulldozers, is used to remove overburden (the rock and soil covering the ore) and extract the ore material. Open-pit mining is suitable for extracting minerals such as coal, iron, copper, gold, and diamonds from shallow deposits.
Q5. What is the purpose of adding flux during the smelting process?
a) To increase the temperature of the smelting furnace
b) To reduce the viscosity of the molten ore
c) To remove impurities and facilitate the separation of metal from ore
d) To enhance the conductivity of the molten metal
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Correct Answer: c) To remove impurities and facilitate the separation of metal from ore
Explanation: Flux is a substance added during the smelting process to aid in the removal of impurities and facilitate the separation of metal from ore. It reacts with the unwanted impurities, such as silica, alumina, and sulfur, forming slag—a waste product that floats on top of the molten metal. This allows for the easy removal of impurities, leaving behind purified molten metal that can be further processed or cast into desired shapes. Common flux materials include limestone, silica, and borax.
Q6. Which method of ore extraction involves the dissolution of soluble minerals using chemical solutions?
a) Leaching
b) Smelting
c) Froth flotation
d) Magnetic separation
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Correct Answer: a) Leaching
Explanation: Leaching is a method used to extract soluble minerals from ore by dissolving them in chemical solutions. In this process, the crushed ore is placed in vats or tanks and treated with a leaching agent, such as acid or cyanide solution. The leaching agent selectively dissolves the desired minerals, which are then recovered from the solution through precipitation or further processing. Leaching is commonly used in the extraction of metals such as gold, silver, copper, and uranium from their ores.
Q7. How does magnetic separation contribute to the extraction of ore?
a) By exploiting differences in magnetic properties of minerals
b) By dissolving soluble minerals in chemical solutions
c) By utilizing differences in density to separate minerals
d) By capturing valuable minerals in a froth
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Correct Answer: a) By exploiting differences in magnetic properties of minerals
Explanation: Magnetic separation is a method used to extract minerals from ore based on their magnetic properties. Certain minerals, such as magnetite, ilmenite, and chromite, exhibit magnetic properties and can be separated from non-magnetic gangue minerals using magnetic separators. By applying a magnetic field to the ore mixture, magnetic minerals are attracted to the magnetic surface or collected by magnetic drums, while non-magnetic minerals pass unaffected. Magnetic separation is commonly used in the mining and mineral processing industries for the concentration of magnetic ores.
Q8. What is the purpose of heap leaching in the extraction of ore?
a) To excavate ore from large open pits or quarries
b) To crush and grind ore into fine particles
c) To dissolve soluble minerals using chemical solutions
d) To separate minerals based on differences in density
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Correct Answer: c) To dissolve soluble minerals using chemical solutions
Explanation: Heap leaching involves the extraction of minerals from ore by percolating chemical solutions through a heap or pile of crushed ore. The purpose of heap leaching is to dissolve soluble minerals, such as metals, from the ore material using chemical solutions, typically acidic or alkaline solutions. As the leach solution flows through the heap, it interacts with the ore particles, dissolving the desired minerals. The pregnant solution containing the dissolved minerals is then collected at the base of the heap and processed further to recover the valuable metals through precipitation, solvent extraction, or electro-winning techniques. Heap leaching is commonly used for the extraction of metals like gold, copper, and uranium from low-grade ore deposits.
Q9. Which of the following techniques is used to separate minerals based on differences in their densities in the extraction of ore?
a) Froth flotation
b) Magnetic separation
c) Gravity separation
d) Leaching
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Correct Answer: c) Gravity separation
Explanation: Gravity separation is a technique used to separate minerals based on differences in their densities. In this method, crushed ore is fed onto a inclined surface or jigging table, where it is subjected to the influence of gravity and water flow. Heavier minerals settle to the bottom of the table, while lighter gangue minerals are washed away by the flowing water. Gravity separation exploits the difference in densities between minerals to achieve separation and concentration. It is commonly used in the extraction of heavy minerals such as gold, tin, tungsten, and diamonds from alluvial deposits or ore streams.
Q10. What role does ore beneficiation play in the extraction of minerals?
a) It involves the crushing and grinding of ore into fine particles
b) It utilizes magnetic properties to separate minerals from gangue
c) It improves the quality and purity of ore by removing impurities
d) It dissolves soluble minerals using chemical solutions
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Correct Answer: c) It improves the quality and purity of ore by removing impurities
Explanation: Ore beneficiation, also known as mineral processing or mineral dressing, is a process used to improve the quality and purity of ore by removing impurities and increasing its concentration of valuable minerals. Beneficiation techniques may involve physical separation methods such as crushing, grinding, screening, and gravity or magnetic separation, as well as chemical processes such as leaching or flotation. The goal of ore beneficiation is to enhance the economic value of ore by increasing its grade, reducing processing costs, and optimizing the efficiency of downstream extraction processes.