Category Geology

Opencast mines are used when the deposit lies near the surface. Overlying earth and rock can be moved by machine or washed away with water. Although opencast mining is cheaper than digging deep mines, some people feel that the environmental costs of it are high, as large areas of land are laid bare and wildlife destroyed. Nowadays great attention is often paid to landscaping the area after an opencast mine has been abandoned. Many are made into parks or wildlife refuges. Planting the areas also helps to stabilize heaps of spoil.

Opencast mining operation involves generation of massive mine waste, altering the existing landscapes, alterations to drainage patterns etc. As a result, significant areas of land are degraded and existing ecosystems are replaced by undesirable wastes. To mitigate the impact on environment, a structured and adoptable environment management practice is being continuously developed at NLCIL. Eco-friendly mining can be broadly brought up under conservation of natural resources, prevention and regulation of polluting activities and action plans for eco regeneration.

Opencast mining operations involve huge quantities of overburden removal, dumping and backfilling in excavated areas. A substantial increase in the rate of accumulation of waste dumps in recent years has resulted in greater height of the dump for minimum ground cover area and also given rise to danger of dump failures. Further, steeper open-pit slopes are prone to failure. These failures lead to loss of valuable human life and damage to mining machinery. There is a need for continuous monitoring of dump and pit slopes, as well as for providing early warning before the occurrence of slope failure. Different technologies have been developed for slope monitoring. After studying the features and limitations of existing slope monitoring systems, it determined that there is a need to provide a reliable slope stability monitoring and prediction system by using a solar power-based long-range wireless sensor network for continuous monitoring of different prevailing parameters of slope stability. An accurate prediction of slope failure using a multiparameters-based prediction model is required for giving warning per the danger levels of impending slope stability. Considering the requirement, a slope failure monitoring and prediction system has been developed by the authors, using a wireless sensor network for the continuous monitoring of slope failure and to provide early warnings. The chapter describes details of slope stability mechanism, parameters affecting slope failure and triggering aspects, monitoring systems, prediction software, and laboratory experiments for calibrating geosensors and field installation of the developed system.

For practical purposes, the Earth’s crust is the only source of minerals. There are, of course, huge amounts of minerals in the Earth’s core and in space, but at the moment it is not possible for us to reach and use them.

Hard rock minerals could be mined from an asteroid or a spent comet. Precious metals such as gold, silver, and platinum group metals could be transported back to Earth, while iron group metals and other common ones could be used for construction in space.

Difficulties include the high cost of spaceflight, unreliable identification of asteroids which are suitable for mining, and ore extraction challenges. Thus, terrestrial mining remains the only means of raw mineral acquisition used today. If space program funding, either public or private, dramatically increases, this situation may change as resources on Earth become increasingly scarce compared to demand and the full potentials of asteroid mining—and space exploration in general—are researched in greater detail.

Asteroid mining could shift from sci-fi dream to world-changing reality a lot faster than you think. Planetary Resources deployed its first spacecraft from the International Space Station last month, and the Washington-based asteroid-mining company aims to launch a series of increasingly ambitious and capable probes over the next few years.

The goal is to begin transforming asteroid water into rocket fuel within a decade, and eventually to harvest valuable and useful platinum-group metals from space rocks. “After that, I think it’s going to be how the market develops,” Lewicki told Space.com, referring to the timeline for going after asteroid metals.

“If there’s one thing that we’ve seen repeat throughout history, it’s, you tend to overpredict what’ll happen in the next year, but you tend to vastly underpredict what will happen in the next 10 years,” he added. “We’re moving very fast, and the world is changing very quickly around us, so I think those things will come to us sooner than we might think.”

In deep mines, water can pose a great danger, undermining layers of rock and causing collapses and flooding, but other types of mining use water to great advantage. Sulphur, for example, can be mined in an unusual process using water. Three pipes of different sizes, one inside another, are drilled into the sulphur reserves. Then extremely hot water, under pressure, is pumped down the outer pipe. This melts the sulphur. Compressed air is then pumped down the central pipe, causing the melted sulphur to move up the middle pipe to the surface. This system was developed by an American engineer, Herman Frasch (1851-1914).

Mining water use is water used for the extraction of minerals that may be in the form of solids, such as coal, iron, sand, and gravel; liquids, such as crude petroleum; and gases, such as natural gas. The category includes quarrying, milling of mined materials, injection of water for secondary oil recovery or for unconventional oil and gas recovery (such as hydraulic fracturing), and other operations associated with mining activities. Dewatering is not reported as a mining withdrawal unless the water was used beneficially, such as dampening roads for dust control.

During some mining activities, particularly gold mining and dredging, water is used for sluicing and flushing out minerals. In most mining operations the majority of this water is recycled, so water loss from rivers and streams is minimised. Water take (abstraction) can be more pronounced where dredging occurs near the riverbed. Loss of water may reduce in stream habitat, elevate water temperatures, and increase summer algal blooms, which may affect invertebrate and mahinga kai communities.