Read the passage and answer the questions:
Methods of Mining
The discovery of minerals in the history of human development, is reflected in many stages in terms of copper age, bronze age and iron age. The use of minerals in ancient times was largely confined to the making of tools, utensils and weapons. The actual development of mining began with the industrial revolution and its importance is continuously increasing. Depending on the mode of occurrence and the nature of the ore, mining is of two types: surface and underground mining. The surface mining also known as open-cast mining is the easiest and the cheapest way of mining minerals that occur close to the surface. Overhead costs such as safety precautions and equipment is relatively low in this method. The output is both large and rapid. When the ore lies deep below the surface, underground mining method or shaft method has to be used. In this method, vertical shafts have to be sunk, from where underground galleries radiate to reach the minerals. Minerals are extracted and transported to the surface through these passages. It requires specially designed lifts, drills, haulage vehicles, ventilation system for safety and efficient movement of people and material. This method is risky. Poisonous gases, fires, floods and caving in lead to fatal accidents. Have you ever read about mine fires and flooding of coal mines in India? The developed economies are retreating from mining, processing and refining stages of production due to high labour costs, while the developing countries with large labour force and striving for higher standard of living are becoming more important. Several countries of Africa and few of south America and Asia have over fifty per cent of the earnings from minerals alone.
Why is surface mining considered as the easiest and cheapest?
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → Because it occurs close to the surface
Option (1) Because of use of high technology — Incorrect. High technology belongs to underground mining and adds to cost.
Option (2) Because of using high safety measures — Incorrect. Safety costs are relatively low in surface mining, not high.
Option (3) Because minerals are extracted from deep earth — Incorrect. Deep ores need underground mining, the costly method.
Option (4) Because it occurs close to the surface — Correct. When a mineral occurs close to the surface, it can be dug out from the open. No shafts or galleries have to be sunk, so the lifts, haulage and ventilation of a deep mine are not needed and overhead costs on safety precautions and equipment stay low; the output is also large and rapid. That makes surface or open-cast mining the easiest and the cheapest way of mining.
NCERT (2025-26): “Methods of Mining … Depending on the mode of occurrence and the nature of the ore, mining is of two types: surface and underground mining. The surface mining also known as open-cast mining is the easiest and the cheapest way of mining minerals that occur close to the surface. Overhead costs such as safety precautions and equipment is relatively low in this method. The output is both large and rapid.…” “Methods of Mining … When the ore lies deep below the surface, underground mining method (shaft method) has to be used. In this method, vertical shafts have to be sunk, from where underground galleries radiate to reach the minerals. Minerals are extracted and transported to the surface through these passages.…”
|
