Chapter 1: Rocks and Minerals extraction

1. Types of rocks

1.1. Igneous rocks

1.1.1. They are formed during the volcanic process. For e.g., granite and basalt. Molten rocks below the surface of earth are known as magma. When they reach the surface they become lava. Magma is hot, liquid rock. It's under pressure from the rocks above it and is found in the outer mantle. When it cools down, it turns to solid rock. As liquid magma rises to the surface, it cools down quickly and turn into lava. Igneous rocks are made of material that were molten, and they contain crystals that are formed when the molten material cools down. The crystals are formed when solutions of minerals cannot absorb anymore dissolved minerals. Therefore, some of the mineral precipitates out of the solution to form the center of the crystal. This then provides a surface for more mineral ions to precipitate as well. The crystal becomes larger in the size as the solution disappears. Small crystals are formed if the rock cools down quickly. This happens if the magma is released to surface through volcanoes. If the magma reaches the crust without going out to the surface then it cools down slowly hence forming larger crystals. Such crystals contain important minerals which can then be used for different purposes in industrial processes. Therefore, heat and pressure are required to form minerals. If they are reduced, crystals will be formed.

1.2. Sedimentary rocks

1.2.1. • Sedimentary rocks are formed by the weathering of rocks on the earth surface, and the accumulation and fossilization of dead plants and animals. Sediments include different sized mineral particles. The smallest particles are clays, then silts, then sands. They all form soils . Particles move from place to another through streams and rivers and then deposit as sediment. Each layer of sediment becomes more compact and harder due to the pressure from the other sediments above it. Examples are limestone, sandstone and shale.

1.3. Metamorphic rocks

1.3.1. • Metamorphic rocks are formed from existing rocks and when heat is above 150 C and pressure is above 1480 atm. This can cause changes to the rock without melting it. The rock therefore changes it Structure and turn into a metamorphic rock. The change can either be chemical or physical or both. Sedimentary and igneous rocks can be metamorphic. Metamorphic rocks can form even more metamorphic rocks. Metamorphic rocks are harder than sedimentary rocks. Examples are marble and slate.

1.4. The rock cycle

2. EXTRACTION OF ROCKS AND MINERALS FROM EARTH • Minerals provide important materials such as coal and oil that provide us with energy

2.1. Searching for minerals: Prospecting: It is the process of searching for minerals carefully at the surface of the rocks.

2.1.1. 1- Remote sensing methods are also used to find deposits on earth's surface. These are processes in which information is gathered about earth's surface from above. One of the methods of remote sensing is photographing land from the air and images are analyzed for any signs of minerals. Images from satellites can also be used. Mineral deposits are seen on the earth's surface and form mineral oxides. They can be detected by the radiation they form and is recorded by satellite. Some satellites send signals to earth arid then collect reflected signals. This system can work under all weather conditions, at night, and even with the availability of clouds. Geologists then visit the location to make sure that the minerals have been identified correctly,

2.1.2. 2- Geochemical: There are also field surveys done on the ground to take samples that are then sent to laboratories for geochemical analysis. The samples can be taken using shallow drilling. The location of the sample points is found accurately using a GPS.

2.1.3. 3-Geophysics: Vibrations such as seismic waves are sent through earth's surface. Different sensors are located at different places on earth. The vibration creates shock waves that travel down to the rock layer and then reflected back to the sensors on the surface. The shock waves show different patterns depending on the type minerals present.

3. Impacts of of rock and mineral extraction

3.1. 1. Economic impacts: . Provides employment for people and taxes for the government: - Jobs are created directly to extract the mineral - Earn foreign exchange . The income earned can be used for buying goods and services and investing in infrastructure projects.

3.2. 2. Environmental impacts: . Loss of habitat as the vegetation is cleared. Therefore, plants do not have a place to grow, so the animals depending on them for food and shelter are affected. . After deep mining has been working for several years, more habitats will be destroyed due to the increased overburden aboveground. . Pollution . Mine waste in rivers.

3.3. 3. Social impacts: .Noise pollution and visual pollution .Houses can be destructed and loss of land,livelihood and cultures. .Health issues including Respiratory and Skin diseases

4. Sustainable use of rocks and minerals

4.1. Sustainable resource: a resource that can be continuously replenished e.g. agriculture, forestry, etc. Sustainable development: development that meets the needs of the present, without compromising the ability of future generations to meet their own needs.

4.2. Strategies for the sustainable use of rocks and minerals:

4.3. 1) Increasing the efficiency of the extraction of rocks and minerals: Mine wastes must be processed for the second time. This allows the valuable minerals to be recovered and reduces the risk of pollution due to mine waste. Chemical treatment of the waste and biological treatment (using microorganisms) extracts much of the valuable mineral still within it. Improvements in the performance of the machines used in mining and processing. Greater use of data analysis by computers (to predict geological conditions).

4.4. 2) Increasing the efficiency of the use of rocks and minerals: Engineering solutions e.g. design steel beams with same strength but using less steel. 3) The need to recycle rocks and minerals: Recycling uses less energy than processing the ores. Recycling also produces less waste and thus, reduces the risk of pollution. 3 ) Legislation: The governments pass laws that require manufacturers to become responsible for recycling and reuse.

5. By: Salma, Zain, Menna and Sumaiyah 10G1

6. Mining rocks and minerals: .An evaluation is done to estimate the size of mineral present in a deposit. .This is to decide whether it is worth extracting. .Drilling of rock samples must be done. .For larger deposits, more drilling is required. .A feasibility study is then prepared to estimate the financial and technical requirements of this mining project, and then it is decided whether to start extracting now or wait until conditions change.

6.1. Types of mining

6.1.1. Surface mining: includes open-cast (open-pit, open-cut) and strip mining.

6.1.2. Open-pit mining is used when a valuable deposit is located near the surface. STEPS INCLUDE : 1) The vegetation is cleared and topsoil removed. 2)The rocks are broken up and loosened with explosives. 3) The loose rock is removed using diggers. 4) The rock or mineral is tipped into trucks or railway wagons. 5) Building materials such as sand, gravel and stone are removed from open pits called quarries. 6) Strip mining is used to mine a seam of mineral. 7) The overburden (overlying rock and soil) is removed as a thin strip. It is mainly used to mine coal.

6.1.3. Sub-surface mining : includes deep and shaft mining.

6.1.4. 1) A vertical shaft is sunk down to the rock layer containing minerals. 2) A horizontal tunnel is made, following the mineral layer. The minerals are extracted by digging (by machines and miners). 3) The loose rock is brought from the mine and piled up on waste heaps on the surface. The minerals are brought to the surface and transported in trucks or trains.

7. Factors affecting the practicality of extraction of rocks and minerals

7.1. Cost of exploration

7.2. Geology

7.3. Climate

7.4. Accessibility

7.5. Environmental Impact

7.6. Supply and demand

8. Managing the impacts of rock and mineral extraction

8.1. Safe disposal of mining waste

8.1.1. - To avoid collapse, mine waste must be kept. - The collapse of mine waste can cause the loss of lives and contamination/ pollution of water. - The mine's location must minimize the risk of water contamination. - To detect any movement or further contamination, the trash must be monitored.

8.2. Land restoration and bioremediation

8.2.1. - Mine waste can be buried with a layer of soil that can be fertilized after (sanitary) landfilling. Plants and trees can be planted in that location when the soil fertility has been improved, assisting in the rebirth of an ecosystem.

8.2.2. Bioremediation is another way used to restore land and is a technique of utilizing living organisms to remove contaminants from trash. in situ treatment refers to the treatment of contaminated trash in its natural environment. The transfer of contaminated trash from a site to a treatment plant is known as ex situ treatment. Usually takes a long time (although can be sped up by adding oxygen and nitrogen). Bacteria and other microorganisms may absorb contaminants and metabolize them into less hazardous compounds. Toxic metals can be bio accumulated by some plants.

8.2.3. Creating natural reserves and lakes: - There are a number of new tree and plant species added. - As their numbers increase, they provide habitat for a variety of animals. - These nature reserves provide as vital green places for human pleasure while also assisting in the conservation of biodiversity. - it can be filled with water to form a reservoir if the rock bordering the hole (formed by the extraction) is non-toxic and impermeable to water.

8.2.4. Using them as landfills: - Landfilling: trash is thrown into a hole, which is periodically levelled and compacted. - Sanitary landfilling: Similar to landfilling, sanitary landfilling uses alternating layers of trash and sand to cover the hole.