LIMESTONE

LIMESTONE :

Every year increasing companies based in Iowa turn out about 35 million tons of raw material from over a wide spread network of 500 locations to bring in a multitude of construction assignments across the state. The major part of this contribute is hauled out from the well-known pits and quarries where nettle dumps and limestone bedrock are nearer to the ground surface.

In locations where geologic and market stipulations authorize, limestone for collective is mined from underground mines. Despite the fact that mining is more expensive than quarrying, the underground mining of mineral can be a combination of both economical and necessity in some areas of the state.


A foremost element of the mining process is breaking up the rock. This breakup is accomplished by detonating volatiles set in blast holes. The rock face to be gusted is typically 40-feet in width by 20- to 25-feet high. A premeditated pattern of 40 to 50 horizontal holes are drilled for the dimensions of 2 inches wide by 12- to 14-feet deep.

An emblematic maneuver can drill and blast up to 5 rounds per day, slackening tons of rock in several diverse headings. The time-delayed detonation not only amplifies blast efficiency, but will greatly shrinks down the ground vibration. These rocks are then lifted into haul trucks which transport it to a rock pounder sometimes based outside the mining area.

Limestone is a sedimentary rock comprising about 15% of the earth’s sedimentary crust. Limestones are generally mined in the method of open pit mining and underground mining based on the economic and environmental conditions.


WHERE DO THEY FORM LIMESTONE :

Limestone is formed in a variety of marine, freshwater and terrestrial environments. Marine limestone is formed in shallow waters near the shoreline, typically in areas of strong tidal activity. These areas can include coral reefs, nearshore sand bars, and areas of wave action. Freshwater limestone is typically found in lake and pond bottoms, river beds, and in areas where there is a lot of groundwater seeping through the soil. Terrestrial limestone is often found in cave systems, where the rock is dissolved by groundwater and then redeposited by dripping water along cave walls and ceilings. Limestone is also found in areas of hot springs, where the rock is dissolved and then redeposited by the hot water.


TYPES OF LIMESTONE:

  • Chalk: Chalk is a soft, white limestone made up of the microscopic skeletal remains of tiny marine organisms such as foraminifera. It is usually found in shallow waters and is composed of calcium carbonate.

  • Coquina: Coquina is a sedimentary rock composed of shells, coral, or other fragments of marine organisms. It is made up of calcium carbonate and is usually found along the coastlines of the southeastern United States.

  • Fossiliferous Limestone: Fossiliferous limestone is a type of limestone composed of the fossilized remains of ancient marine organisms. It is usually found in shallow seas and is composed of calcium carbonate.

  • Travertine: Travertine is a type of limestone that is formed by mineral deposits from hot springs or limestone caves. It is usually found in warm climates and is composed of calcium carbonate.

  • Dolomitic Limestone: Dolomitic limestone is a type of limestone that contains a significant amount of magnesium carbonate. It is usually found in mountainous regions and is composed of calcium carbonate and magnesium carbonate.

  • Oolitic Limestone: Oolitic limestone is a type of sedimentary rock formed by the accumulation of oolites, which are tiny spherical grains of calcium carbonate. It is usually found in shallow seas and is composed of calcium carbonate.



USES OF LIMESTONE :

Limestone is a sedimentary rock composed mainly of calcium carbonate (CaCO3), usually calcite. It forms when the evaporation of seawater or freshwater leaves behind mineral deposits. It is formed in a variety of environments and can be caused by a number of different processes.

1. Biochemical: Limestone forms from the accumulation of skeletal remains from organisms like coral, foraminifera, and mollusks. As these organisms live, their calcium carbonate shells are deposited on the seafloor. Over time, these shells accumulate and form a sedimentary rock.

2. Chemical: Limestone can also form from the precipitation of calcium carbonate from solution, such as in caves. As water evaporates, it leaves behind minerals, which eventually form limestone.

3. Clastic: Clastic limestone is formed from the erosion and accumulation of other sedimentary rocks, such as sandstone and shale. These rocks are broken down and the calcium carbonate is deposited.

4. Evaporative: Evaporative limestone forms when water evaporates and leaves behind minerals, such as calcite and dolomite. This process often occurs in caves, where water seeping down from the surface carries dissolved minerals, which are then deposited as the water evaporates.

5. Metamorphic: Metamorphic limestone forms when sedimentary limestone is subjected to extreme heat and pressure, which causes the minerals to recrystallize and form new rocks.


SURFACE LIMESTONE MINING:

All over the world, the limestones are generally mined from a quarry or the open pit mining. It is the easiest way to remove the limestone without causing much destruction. In surface mining or open pit mining, the top soil and the overburden covering the mineral is removed. Then by the process of drilling the rocks or broken. Overburden or large rocks that are difficult to break through drilling are removed by the explosives to extract the limestone. Then the ore is hauled to the crushing plant. The equipment varies according to each process based on each operation. Surface mining requires only simple machines to operate the mine when compared to underground mining. There are many factors to consider in surface mining are the selection of equipment required at each operation, production capacity, size and shape of the deposit, haul distances, estimated life of the operation and transportation cost to reach the urban centers.



UNDERGROUND MINING:


The underground mining is done when the ore is present in more than 100m depth or when the availability of limestone is abundant. Other factors that determine underground mining is that topsoil covering the mineral is hard like rocks. The first process to start underground mining is considering the economical factors. As the specialised equipment and machineries are needed for underground mining, it is only done when there is a large deposit of the minerals. There are a series of processes in case of underground mining, let us get a glance through this.

In case of drilling in the underground mining, drilling equipment like horizontal drills and down hole track drills are required. The drilling process completely differs from the open pit mining. The horizontal and hole track drill will produce much smaller blast holes. Explosives are sent to the hole and produce a lower volume of rock with each blast. Other equipment that are required in underground mining are powder loaders, scaling rigs and roof bolting equipment. The powder loaders send the ammonium nitrate fuel oil mixtures into the blast holes. After blasting the loose rocks from the ribs and roof of the mine are removed by the scaling rigs. Roof bolting equipment is also used in underground mining.



The room and pillar type operations are undergone to recover the ore from both headings and the benches. It has several benches in the underground with height upto 30m. The thickness depends on the thickness of the deposit. The drill used will determine the size of the room. To maximize the amount of rock produced V-type drill pattern is used. Then the extracted rocks are sent for further processing.

The underground mining is considered to be the most efficient method that will be used in the future. However, there are many concerns about underground limestone mining including noise, dust, vibrations due to blasting and other traffic associated with quarry operations.