Limestone Definition

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Limestone Definition

Limestone is a sedimentary rock, formed organically, from which lime is extracted and contains a percentage of (10%) of Dolomites called Limestone Dolomite. It is generally white in color but may exist in various different colors such as; yellow and grey; due to the presence of some impurities such as sand, silt and iron oxide, etc. Overall, its texture is smooth or rough granules and sometimes it is in the form of veins.

Its demand is proportional to its content of Calcium Oxide (CaO) and its degree of hardness usually determines its optimal utilization; as it is an important component of most industries and it is sufficient to mention that it is a key substance in the Food Industry.

Limestone exists in large margins in the Earth’s crust and the Kingdom of Saudi Arabia is rich with this mineral. And given that the best types of Limestone, containing the highest percentage of Calcium (not less than 95% and up to 99%), are found in the Eastern Region of Al-Kharj, it was the vision of Astra Mining to establish the first core of its mining industry there. Limestone constitutes approximately (20%) of the sedimentary rocks of the Earth’s crust.

It is one of the most important raw minerals that is utilized as a primary or secondary material in most production industries, such as; steel, paints, plastics, agriculture, glass, marble, sterilization, medicine, ceramics, putty and food, etc., as it often contains limestone non-carbonic metals, such as; volcanic morsels, silica or clay and the remains of fossils and metals, etc.

An overview of some uses of Astra Limestone in; 
1) Portland Cement Industry; Limestone is considered the core and the main structure of this industry with no less than (76%); where it is mixed with non-metallic minerals which are chemically treated. 
2) Anhydrous Sodium Carbonate Industry or Soda Ash; which is an important material extracted from limestone for the glass industry, cleaning and sterilization through the reaction of carbon dioxide with sodium chloride and ammonia. 
3) As Agent in Iron and Steel Smelters; iron often contains impurities as silica and aluminum and about (410 kg) of limestone is needed to produce one ton of iron. 
4) Rock Wool Industry; impure limestone mud is fused in ovens to extract slag through a narrow opening and then steam-blown with great force to produce threads of calcium silicate which are collected as Rock Wool to be utilized for heat insulation. 
5) Metal Fillings Industry; Limestone is one of the most important mineral used for metal fillings due to the ease of its milling, its low absorption of oils and ease to blend. It is also used in the manufacturing of bitumen rolls to cover walls, boats, cars and plumbing. 
6) Food Industries; Pure non-toxic Limestone free from lead and copper is used in the manufacturing poultry feed and food processing to extract sugar from beets. 
7) Ornamental Stones Industry; Limestone is used for floor covering, as well as the internal and external facades of buildings. 
8) Building Blocks Industry; Limestone is used in the crushed gravel and concrete industries, as well as sewer filters. It is also used for road paving after mixing it with bitumen where it remains holding a high percentage of silicon dioxide. 
Specifications of Limestone 42.5 Min Lost on Ignition <5% Under/Oversize 0.5% Max Impurities 0.17%max Fe2O3 1% max SiO2 and insole 0.5% max MgO 1% max MgCO3 54.5 min CaO 97% min CaCO3 30-70 min Size


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