Day 72 – Q 1.What is open cast mining? How does it affect the land? What are the alternatives to open cast mining? Discuss.
1. What is open cast mining? How does it affect the land? What are the alternatives to open cast mining? Discuss.
ओपन कास्ट माइनिंग क्या है? यह भूमि को कैसे प्रभावित करता है? ओपन कास्ट माइनिंग के विकल्प क्या हैं? चर्चा करें।
Open-cast mining is a surface mining technique of extracting rock or minerals from the earth by their removal from an open pit or borrow.
This form of mining differs from extractive methods that require tunneling into the earth, such as long wall mining. Open-pit mines are used when deposits of commercially useful minerals or rocks are found near the surface; that is, where the overburden is relatively thin or the material of interest is structurally unsuitable for tunneling (as would be the case for sand, cinder, and gravel). For minerals that occur deep below the surface—where the overburden is thick or the mineral occurs as veins in hard rock—underground mining methods extract the valued material.
Effect of open cast mining on land
- Open-cast mining changes geological, hydrological and geotechnical conditions.
- It influences the existing ecological system and landscape.
- During mining stage, land is damaged and degraded. Excavation of coal and overburden dumping along with other infrastructural development is responsible for this damage and degradation.
- Impact of land degradation is observed as loss of forest cover, reduction and extinction of wildlife, reduction of agricultural land, destruction of geologic column, soil erosion, hydrological imbalance, socioeconomic problems, etc. in active mining areas
- The dust and noise affect not only the atmosphere and soil, but also the whole human living space in the exploited territories.
- Open-pit mines create a significant amount of waste. Almost one million tons of ore and waste rock can move from the largest mines per day, and a couple thousand tons moved from small mines per day
Alternatives to open cast mining
- In-situ recovery (ISR), is an extraction process designed to leave a mine’s physical location undisturbed. It is touted as an environmentally cleaner method of extraction. In a nutshell, in situ means “in the natural or original position,” and the process seeks to remove mineral ore from right where it sits, as opposed to removing large amounts of rock and earth above and around it (which, of course, is typically how mine sites operate).
ISR is commonly used to recover uranium. However, the process is also used to mine copper, and to extract deposits of water-soluble salts such as sodium chloride and sodium sulfate.
- Block caving – Block cave mining is an underground mass mining method that allows for the bulk extraction of large, relatively lower grade, ore deposits with substantial vertical dimension. In block caving, a large section of ore is initially undercut by drilling and blasting, creating a large unsupported roof that will start to collapse under its own weight and instability. The broken ore then breaks apart and falls into a series of pre-constructed funnels, or drawbells, and access tunnels developed underneath the caving rock mass to form ore extraction drawpoints.
Open-pit mining is to be considered one of the most dangerous sectors in the industrial world. It causes significant effects to miners’ health, as well as damage to the ecological land. Alternative technologies must be made part of mining policies.