Rocks and Minerals .pptx for environmental management

EVM - IGCSE '
(0680)

1. Rocks, minerals and their exploitation

2. Rock types and rock cycle https://youtu.be/ZkHp_nnU9DY

3. 1.1 Formation of rocks What are rocks? Rocks are made of  grains  that fit together. Each grain in the rock is made from a mineral, which is a chemical compound. The grains in a rock can be different colours, shapes and sizes.

4. Igneous rocks Formation The inside of the Earth is very hot - hot enough to melt rocks. Molten (liquid) rock forms when rocks melt. The molten rock is called  magma . When the magma cools and solidifies, a type of rock called igneous rock forms. What are they like? Igneous rocks contain randomly arranged interlocking crystals. The size of the crystals depends on how quickly the molten magma solidified. The more  slowly  the magma cools, the  bigger  the crystals. You may have done an experiment at school with a substance called salol. If molten salol cools slowly, you get big crystals. If it cools quickly, you get small crystals.

5. Examples 1. Obsidian and basalt If the magma cools quickly, small crystals form in the rock. This can happen if the magma erupts from a volcano. Obsidian and basalt are examples of this type of rock. They are called  extrusive  igneous rocks because they form from eruptions of magma. 2. Granite and gabbro If the magma cools slowly, large crystals form in the rock. This can happen if the magma cools deep underground. Granite and gabbro are examples of this type of rock. They are intrusive igneous rocks because they form from magma underground. Unlike sedimentary rocks, igneous rocks do not contain any fossils. This is because any fossils in the original rock will have melted when the magma formed

6. Sedimentary rocks Formation of sedimentary rocks A river carries, or transports, pieces of broken rock as it flows along. When the river reaches a lake or the sea, its load of transported rocks settles to the bottom. We say that the rocks are   deposited . The deposited rocks build up in layers, called sediments. This process is called  sedimentation. The weight of the sediments on top squashes the sediments at the bottom. This is called  compaction. The water is squeezed out from between the pieces of rock and crystals of different salts form. The crystals form a sort of glue that sticks or cements the pieces of rock together. This process is called  cementation. These processes eventually make a type of rock called sedimentary rock. It may take millions of years for sedimentary rocks to form. These are the different processes in order: sedimentation → compaction → cementation

7. Examples: What are they like? Sedimentary rocks contain rounded grains in layers. Examples of sedimentary rock are: sandstone erosion: Sedimentary rocks like sandstone have layers chalk limestone sandstone shale The oldest layers are at the bottom and the youngest layers are at the top. Sedimentary rocks may contain fossils of animals and plants trapped in the sediments as the rock was formed.

8. Metamorphic rocks Metamorphic rocks are the third type we'll look at. They formed from other rocks that are changed because of heat or pressure . Formation Earth movements can cause rocks to be deeply buried or squeezed. As a result, the rocks are heated and put under great pressure . They do not melt , but the minerals they contain are changed chemically, forming metamorphic rocks. Sometimes, metamorphic rocks are formed when rocks are close to some molten magma, and so get heated up. Remember that metamorphic rocks are not made from melting rock. (Rocks that do melt form igneous rocks instead.)

9. What are metamorphic rocks like? What are metamorphic rocks like? When a metamorphic rock is formed under pressure, its crystals become arranged in layers . Slate , which is formed from shale , is like this. Slate is useful for making roof tiles because its layers can be split into separate flat sheets. Marble is another example of a metamorphic rock. It is formed from limestone . slate  is formed from shale marble  is formed from limestone

10. Work on it  Interactive rock cycle, such as in www.learner.org/ – search for ‘rock cycle’

11. The Rock Cycle

12. 1.2 Extraction of rocks from the earth Learning objectives: describe the following methods of extraction of rocks and minerals from the Earth: – surface mining opencast /open-pit / open-cut / strip mining – subsurface mining deep mining /shaft mining discuss the factors that affect the decision to extract rocks and minerals

13. Ores: rock with enough important elements to make worth mining What do people extract from the Earth? 1. Coal and oil provide us with energy and many chemicals used in industry. 2. Metallic ores provide us with metal & alloys needed to make products. Such.. 1. Mobile phones 2. computer 3.cars 4.Wires and nails 3. Minerals Then the demand from developed and developing countries is increasing.

14. methods used to search for deposits of mineral the Earth.ls that maybe found in Prospecting: process of searching for minerals The simplest way to find mineral deposits is to look at the surface of rocks….this process is called prospecting…it actually found all the deposits of minerals world wide. Remote sensing ( Aerial photography) method is used to find…Deposits on Earth`s surface. Images, and other data from satellite can be used to analyze on large areas. Photographs are taken with an overlap both front and back and side to side, 3D (mapping) https://youtu.be/nFS5IOdzRUc   Drone Survey of a large open pit Mine

15. How mineral deposits are detected? When mineral deposits are weathered they produce mineral oxides . They can be detected by: Unique radiation pattern : recorded by a satellite and downloaded to a computer for analysis. Other satellites operate by sending signals to the surface of the earth and collecting reflected signals                                                                               It works in all weathers and at night

16. How can we locate valuable mineral ores in the rocks below the surface ?   Process: Satellite images can locate them . Then computers are used to process the data from the region of interest. Satellite`s positioning system record the exact location . Geologists visit the location to confirm the minerals to identify the minerals correctly. Benefits: Note: using satellites means large areas can be geologically mapped quickly & and at low cost.

17. https://youtu.be/nRxhNtpp3Xk Oil exploitation and discovery

18. Methods used to identify mineral ores present in rocks: A. Geochemical: the chemical properties of rocks Field surveys on the ground are used to take samples. They are sent to the laboratory for geochemical analysis   so the chemicals in the samples are identified.  (samples can be taken from stream sediments, soil or rocks using shallow drilling ) How do they select the points where samples are taken? By overlaying a grid on a map of the survey area. By using GPS ( Global positioning System) 

19. B. Geophysics: series of vibrations (seismic waves)are sent through the  Earth`s surface. How!!!!! 1. Several sensors at different distances from the source of vibrations are laid on the ground 2. Vibrations will create a shock waves that travel down into the rock layers and reflected back to the sensors on the surface. 3. The shock wave record different patterns depending on What minerals are present in the rock layers Note: explosives can be used instead of vibrations https://youtu.be/hxJa7EvYoFI

20. discuss the factors that affect the decision to extract rocks & mineral s Learners develop their map interpretation skills by describing the distribution of coal mines shown on a map, using www.gov.uk/government/organisations/the-coal-authority  search for ‘Coal Authority interactive map viewer’ or  www.mapsofworld.com    search for ‘world coal deposits’ Learners look at a photograph of the location of a quarry or quarries and identify the pros and cons of its site and possible mineral extraction.  Possible resources are www.alamy.com

21. Major factors affecting exploitation of mineral resources in the world are as follows:  (i) Richness or Grade of the Ore  (ii) Size of Deposit  (iii) Method of Mining  (iv) Accessibility  (v) Transportation Facilities  (vi) Stage of Industrial Development  (vii) Technology  (viii) Other Factors.

22. Mining rocks and minerals To make sure that the deposits of the mineral ores are LARGE to be extracted.... resource evaluation is carried. What is the aim of this evaluation ? To estimate the grade, size, the mixture of the mineral ores & tonnage of the mineral of interest presented. How do we carry it? Drilling to collect rock samples for small samples Drilling to collect followed by grid pattern on the ground

23. From the information collected before.. We can classify the deposits into: mineral OR reserve   Finally... A feasibility study is carried out to evaluate all the financial and technical RISKS A final decision maybe to develop a mine straight away.

24. A possible resource is www.greatmining.com search for ‘Surface mining’ and ‘Underground mining’. Learners study images of surface and subsurface mines and further categories the images as opencast, open-pit, open-cut, strip mines, deep mines, shaft mines https://youtu.be/hYEMIGMyVGo Follow the Link

25. Methods of extraction Surface mining  Subsurface mining Open cast Deep mining Open pit Shaft mining Open cut Strip mining 

26. Surface mining is... Type of mining used when either the mineral is exposed (located) on the surface OR overlain (buried) by only small amounts of overburden. Overburden: it is the material above the deposit (the rock and soil....overlying an economically viable mineral deposit). The overburden must be removed to be used later for mine restoration. https://youtu.be/4WbaONJEbRE

27. 1. Open -pit is called open -cast or open- cut They are dug into benches   Fig.1.13/ pg.13 The walls are kept into angles to reduce the risk of rock fall Roads have to be made to allow the removal of deposit the mineral deposits . Building materials such as gravel, sand and stone are removed from the open pits ( quarries ) Reasons why open pit mines eventually stop being worked? 1. As much as valuable deposit has been removed. 2. the amount of overburden that needs to be removed has increased to a point where it is not profitable.

28. 2. Strip mining: Strip mining is mainly used for to mine COAL near the surface. Strip mining is used to mine a seam of minerals. First, the overburden is removed Large excavator  with very large bucket wheel move thousands of tonnes of materials every hour Fig.1 https://youtu.be/1QP-dSXhKcs

29. Sub-surface mining Involves digging tunnels into the ground to reach mineral deposits that are too deep. 1. Sometimes HORIZANTAL ( drift) tunnels are dug directly into the COAL seam in the side of a hill or mountain....through an ADIT Adit : the entrance to an horizantal (drift) mine. 2. Slopping tunnel is dug to reach deeper Deposits. 3. Shaft tunnel , vertical tunnel is dug. Mining machinery can be lowered down the sloping tunnels while rock & minerals Ore are hauled up to the surface. https://youtu.be/ruVCy4xNkEU

30. The miner`s job is to make sure all the machinery is working correctly and safely             Open-pit mines          Shaft mining Deposits near the surface can be extracted by this method More difficult ( supply of fresh air and water drainage must be provided) Less technical difficulties  Dangerous of collapsing tunnels Low extraction cost per ton ( lower deposit value) High costs per tonne ( high deposit value) Poisonous gas,  Explosions underground Underground fire

31. Fig.1.14/ Pg.10

32. In Situ Leach Mining of Uranium (Updated October 2017 ) In 2016, 48% of world uranium mined was from ISL operations. Most uranium mining in the USA, Kazakhstan and Uzbekistan is now by in situ leach methods, also known as in situ recovery (ISR). ISL mining of uranium is undertaken in Australia, China, and Russia as well. In USA ISL is seen as the most cost effective and environmentally acceptable method of mining, and other experience supports this. 

33. Conventional mining involves removing mineralized rock (ore) from the ground, breaking it up and treating it to remove the minerals being sought. In situ leaching (ISL), also known as solution mining, or in situ recovery (ISR) in North America, involves leaving the ore where it is in the ground, and recovering the minerals from it by dissolving them and pumping the pregnant solution to the surface where the minerals can be recovered. Consequently there is little surface disturbance and no tailings or waste rock generated. However, the orebody needs to be permeable to the liquids used, and located so that they do not contaminate groundwater away from the orebody.

34. https://youtu.be/FmaNoyfQtWQ in-situ leaching https://youtu.be/FmaNoyfQtWQ

35. Self-assessment 1.3, 1.4/ pg.10 Factors affecting the viability of extraction minerals? ( whether I should mine the deposit mineral or NOT) 1. the costs of exploration 2. geology 3. climate 4. accessibility & transportation can be difficult and expensive 5. environment impact 6. supply & demand

36. Strike rate: the frequency with which attempts to find a desired mineral are successful. Greenfield sites Brownsfield sites Areas that have never mined before for minerals Areas that have already mined Chances to find metal ores is rare Chances usually are higher even for low-grade deposits The strike rate ranges from 1:50 to 1:100 or maybe 1:1000 Strike rate  is higher than greenfield

37. The cost of mining The cost of mining one tonne of ore must be calculated. Deposits near the surface deeper deposits Can be extracted by open pit mining Fewer technical difficulties to mining on large scale using this method Can be extracted by shaft mining Only deposits with high value can be mined economically Low extraction cost Higher cost per tonne

38. The quality of the mineral deposit…is it high grade ores or not? High grade ores will yield more than low grade the size of deposit is also important...!!! Small deposits of high-grade ore & high value may be worth mining. Small deposits of low-grade ore & low value may be left as RESERVE . Transportation ores to processing plants may be difficult and expensive…. Building roads or rails, ports. The cost for transporting I tonne of ore over 1Km can be calculated. If the ore is going to be exported, large ships, called Bulk Carries can be used to keep the transport costs low.

39. If the ore is going to be exported, in large tonnes ( such IRON)..then Ways to keep the cost of transportation low: large ships, called Bulk Carries can be used. Carry out some processing of the ore at the mine. Direct shipping iron ores (DSO): iron ores that have enough content of iron that they do not need processing at the mine The aim of processing is to concentrate the mineral ore and separate it from the waste material. waste material is stored in the mine. In this case this type of processing produces a higher grade of ore so it has a higher value per tonne .

40. Off to the market… Fig.1.15/ pg 11 1. mining companies can only start work after they have been given a license to extract a deposit. 2. The government of any country will want to earn some money from mining activity. 3. This means there will be taxes to be paid to the government for every tonne of mineral ore extracted. 4.Increase in world demand for any mineral ore will drive the price to increase. 5. Change in SUPPLY & DEMAND can also increase or decrease. ( if the world prices remain high….then the deposits that could not be mined become worth mining. And, only when the world price rises again can a new mine become profitable) 5. Recently; The world price of iron ore has dropped because supply > greater than demand Supply and demand: the relationship between how much of commodity is available and how much is needed or wanted by consumers of the product.

41. Predicting solutions for the supply & demand issue is… Mining companies try to predict future demand very carefully so that periods of selling ore at less than the cost of production are kept Minimum Check out Figure 1.15/ pg.11

42. 1.3 Impact of rock and mineral extraction Environmental impacts: Can be ranged on large scale from habitat destruction to pollution of the atmosphere. Ecological impacts a. loss of habitat for some species of plants and animals, especially when part of the vegetation is extracted. b. Deep mining type can cause extra damage over several years and mine waste stored aboveground increases. c. After the seam of valuable minerals have been removed, the new land surface will have less biodiversity, so plant and animal habitat will be lost from the area even after its restored.

43. Key Word… To ensure that mining companies are following code of conduct towards the environmental impacts, they have to have a license application       What is license application? The license application is usually approved if the company has a plan to keep the loss of habitat as small as possible and then to restore the land after mining has finished. The company must have detailed plans to control the amount of damage. Pg.12

44. 2. Pollution:   noise, water, land, air and visual pollution.   noise pollution can disturb the behavior of many animal species air pollution can cause health problems for people and release dust        particles, and can be dangerous to human health, leading to lung diseases.   Land pollution, lands around the mine will become polluted by mine waste   leads to toxic the nature and harm the animals and plants Visual pollution 

45. Key word…. Biomagnification              water that drains through mine waste, comes directly from mine          shaft can cause dramatic changes to the population living nearby.         Water can become acidic and dissolved toxic metal ions in it…         however, organisms absorb these ions and retain them in their          body, will reach concentrations much higher than that in water….         this is called Bioaccumulation Biomagnification :  The concentrations increase further in organisms that are higher up the food chain, and cause death of top consumers

46. Economic impacts: Mineral extraction usually benefit local & national economies Extracting valuable minerals provide employment locally and nationally  Extracting valuable minerals provide taxes for the government If the minerals are refined in the same country...then more jobs will be created Transport employment will be created, healthcare & eductaion will be required to maintain the labors families.

47. 1.4 Manging the impact of rock & mineral extraction Managing of a mine should start & end with a PLAN for   a. safe waste disposal   b. return the land to its original state when mining is over

48. Safe disposal of mining waste In the past, mining waste was usually been put in piles, near the point of extraction Today, safe storage and disposal of mine waste is one of the most important aspects of any mining licence application

49. Land restoration and bioremediation When mining is finished the land must be restored  Mine waste can be reshaped to blend in with surrounding landforms The waste can then be covered to enrich the soil with fertilizer. Such an area can then be planted with TREES. This will help other plants and animals to colonies the area. By time ,the soil will be improved by the addition of organic matter from plant and animal waste…… This can happen in COAL mining Bioremediation Process in which living things are used to remove toxic chemicals (pollutants)   from a natural site.

50. Some mine waste does not allow the growth of tree roots, so other methods have been used. CONTAMINATED WASTE can be treated where it was left( in Situ treatment) by BIOREMEDIATION

51. Bioremediation: Process in which living things are used to remove toxic chemicals (pollutants)   from a natural site. How? Many organisms are able to break down toxic substances into less hazardous substances. Bacteria found in soil are able to absorb pollutants and process them via metabolic pathways into less harmful substances. Bacteria take in pollutants they usually gain either energy or nutrients. Microorganisms can remove and process pollutants at faster rate if theres enough oxygen and nitrogen. Some plants are able to bioaccumulate toxic metals….But they must be removes later one, so the ground will remain less toxic.

52. After this treatment: The land will turned into NATURE RESERVE , but not a farming land. Several trees and herb species will create a new habitat. Reserves will become green spaces for human recreation. See Former granite quarry on Bornholm, Denmark/ pg.16 4. Mineral extraction can creates large holes in the landscape, it can be filled with water to for a RESERVOIR. 5. This water can be used for safe drinking unless household waste is filled in it …. In this case it will be Landfill

53. How successful are these strategies? The Society for Ecological Restoration International (SERI) proposed that: A successful scheme will return the site to as close as possible to the native ecosystem that existed before the mining began. Scientists believe that allowing a site to undergo a natural process of recolonization and slow change to the environment ( is called SUCCESSION) be actually the most beneficial.

54. 1.5 Sustainable use of rocks & minerals Sustainable use means….use that meets the needs of the present without affecting the ability of future generations to meet their needs. A fully sustainable resources will never ran out….this can be achieved in: Fisheries Agriculture Forestry those resources are biological and can be regrown Rocks and minerals will not last indefinitely

55. Human societies should: Use any resources with care Plan and control the use of any reserve to provide the most benefit to people. Maintain economic growth and stability and prevent widespread environment damage. Since human population is in increase, so the best that can be achieved is the prolonged use of resources with limited environmental damage and most benefit for human resources.

56. Example on how to find substitutes for the use of relatively scarce materials: COPPER…is quite rare substance and is used for conducting electricity When the purpose is to transmit information, copper can be substitute by fibre optic cables. Fibre optic cables are made of from much more common element SILICA Then…several strategies can be used to make the exploitation of rocks and minerals more sustainable