Question

Depending on the mode of occurrence and the nature of the ore, mining is of two types: Surface and underground mining. Surface mining is 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 are relatively low in this method. The output is both large and rapid. When the ore lies deep below the surface, an 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. It requires specially designed lifts, drills, haulage, vehicles, ventilation system for safe and efficient movement of people and materials. This method is risky. Poisonous gages, fires, floods, and cave-in bad to fatal accidents. 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 forces and striving for a higher standard of living are becoming more important. Several countries of Africa and a few of South America and Asia have over fifty percent of the earnings from minerals alone.

Shaft method mining is used for the minerals which ______

Options

• found at great depths

• found at the surface

• found near the surface

• which are heavier

Answer 1

Shaft method mining is used for the minerals which found at great depths.