Mining and Development of Mineral Resources; Fossil Fuels
Mining refers to a set of processes through which useful resources are withdrawn from a stock of any nonrenewable resource.
Ores are naturally occurring materials that can be profitably mined.
Mining Methods
Open Pit Mining commonly involves large holes that extract relatively low-grade metallic ore.
Strip Mining extracts horizontal layers of ore or rock.
Placer mining- where gold or diamonds are extracted from river and beach sediment by scooping up the sediment and then the ore by density.
Quarrying- refers to surface mining that does not require complex processing. Quarrying is used to mine sand and gravel, crushed stone aggregate, and many industrial minerals (like limestone, gypsum and magnetite).
Underground Mining Methods- are used when the mineral deposit is too deep underground for metallic ore (gold, silver, copper, iron, etc.). It can involve numerous steps including crushing, grinding, and physical separating.
a. Processing metallic ore (gold, silver, copper, iron, etc.) can involve numerous steps including crushing, grinding, and physical separating.
b. Smelting – heating the ore minerals with different chemicals to extract the metal
c. Leaching – using chemicals to dissolve the metals from a large volume of crushed rock.
Fossil Fuels are a form of energy derived from ancient living organism. The term "fossil" refers to the remains or imprints of past living beings. Fossil fuels mainly originate from the remnants of plants that existed in past geologic eras.
Coal is a black combustible rock made up of elemental carbon, hydrogen, oxygen, nitrogen, and varying amounts of sulfur.
Four Stages
1. Peat- is considered the precursor form of coal, contains less than 60% carbon and is composed wholly of volatile matter.
Left to itself, it burns like wood, gives less heat, emits more smoke and leaves a lot of ash.
2. Lignite- is also known as brown coal and is composed of 65-70% carbon and 53-63% volatile matter.
It undergoes spontaneous combustion.
3. Bituminous coal- is a sedimentary rock composed of 70-86% carbon and 31-46% volatile matter.
Calorific value is very high due to the high proportion of carbon and low moisture.
4. Anthracite- is deemed the highest form of coal due to its carbon content ranging from 86-98% with 3-8% volatile matter.
Ignites slowly and burns with a nice short blue flame.
Petroleum and Natural Gas
Petroleum comes from the Latin words petra which means “rock”, and oleum which means “oil”. It is a naturally occurring liquid composed of complex hydrocarbons and is found in geologic formations underneath the Earth’s surface.
Petroleum is a fossil fuel derived from large quantities of microscopic aquatic organisms such as algae and plankton. The remains of these organisms settled on the sea or lake bottoms millions of years ago and were buried beneath fine sediments in anoxic conditions. With increasing pressure and temperature due to continuous burial, the organic matter in these organisms transforms into a waxy material known as kerogen and eventually into hydrocarbons through the process of catagenesis.
Petroleum forms within a specific depth, pressure, and temperature range known as “oil window”.
On the other hand, if the temperature increases beyond the oil window, oil is converted into natural gas in a process called thermal cracking.