Limestone (Limestone) referred to as limestone, to calcite Is the main ingredient Carbonate rock . Sometimes contain dolomite , Clay minerals And detrital minerals, gray, gray, gray black, yellow, light red, brown red and other colors, hardness is generally not large, and Diluted hydrochloric acid There's a violent chemical reaction. Belong to the classification according to the cause Sedimentary rock .

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minification

Chinese name: limestone
Foreign name: Limestone
Main component: Carbonate rock
Abbreviated form: limestone
categorize: Granular, biological skeleton and chemistry, biochemistry

causation: Biological deposition, chemical deposition and secondary
structure: Clastic structure and grain structure
Classification by cause: Sedimentary rock
Nomenclature validation: Geological nomenclature Validation Committee ^[2]
Announcement time: The year 1993 ^[2]

catalogue

Rock classification

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limestone

Limestone is mainly found in Shallow sea Was formed in the environment. According to the origin of limestone can be divided into granular limestone (water transport, sedimentary formation), Biological skeleton Limestone and chemistry and biology Chemical limestone . According to the structure can be subdivided into Bamboo leaf limestone , oolitic limestone, Leopard limestone Lump limestone and so on. The main chemical component of limestone is CaCO 3 easy corrosion Therefore, stone forests and karst caves are formed in limestone areas, called Karst topography .

Limestone is fired lime and cement The main raw material is the flux for iron and steel making. ^[1]

Rock structure

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The structure of limestone is more complex, there are two kinds of clastic structure and grain structure. The clastic structure mainly consists of particles, micrite matrix and Sparry cement Constitute. Particles, also known as particle chips, mainly have endoclast The micrite matrix is composed of bioclasts and oolites Calcium carbonate Stucco composed of fine chips or crystals, with particles mostly smaller than 0.05 mm, sparry cement is a chemical sediment filled in the pores between rock particles, and is greater than 0.01 mm in diameter Calcite crystal Particles; The grain structure is a crystal particle precipitated by chemical and biochemical processes.

Structural classification

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	Plaster content /%	Particle content /%	particle	Grade particle	Biological lattice
endoclast	biont	oolith	crumb	Fecal pellet
I granular stucco limestone	I 1 granular limestone	10 25 50 75 90	90 75 50 25 10	Endoclastic limestone	biolith	Oolitic limestone	Clump limestone	coprolite	Ii crystalline limestone	Ⅲ reef stone stone grey rock
Ⅰ2 contains plaster particles limestone	Clastic limestone with plaster	Stucco biological limestone	Stucco oolitic limestone	Stucco limestone	Stucco coprolite
I 3 marl granular limestone	Intraflastic limestone	Stucco biolimestone	Marl oolitic limestone	Stucco mass limestone	Stucco coprolite
I 4 granular marl limestone	Endoclastic marl limestone	Biomass stucco limestone	Oolitic marl limestone	Clump limestone	Fecal pelitic limestone
Ⅰ5 granulated stucco limestone	Endoclastic limestone	Biostucco limestone	Oolitic limestone	Oolitic limestone	Copropelitic limestone
I 6 stucco limestone	Stucco limestone

(According to East China Petroleum Institute)

Rock distribution

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A limestone produced by biochemical processes and often rich in organic remains. Limestone generally contains some dolomite and Clay minerals When the clay mineral content reaches 25% to 50%, it is called argillite . When the dolomite content reaches 25% to 50%, it is called Dolomitic limestone . Limestone is widely distributed, the lithology is uniform, easy to mining and processing, is a very widely used building materials.

Especially in North China and the southern part of Northeast China, due to the climax of the Middle Ordovician transgression, thick and pure limestone was generally deposited, which is the raw material of cement and metallurgical industry with industrial value.

Formation process

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The main components of limestone are Calcium carbonate Can be dissolved in water containing carbon dioxide. In general, one liter of water containing carbon dioxide can dissolve about 50 mg of calcium carbonate.

The calcium carbonate deposited in the lake sea, after losing water, compacted and cemented up to form a rock, called limestone. The mineral composition of limestone is mainly calcite (accounting for more than 50%) and some impurities such as clay and silt. Most of the formation of limestone is related to biological action, and the limestone formed by the accumulation of biological remains has coral limestone, shell limestone, algae limestone, etc., the general name of biological limestone. Calcium carbonate in aqueous solution (CaCO 3 Limestone formed by chemical precipitation is called chemical limestone. Such as ordinary limestone, siliceous limestone, etc.

Rock type

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limestone

Limestone is one of the most widely distributed minerals in the Earth's crust. According to its deposition area, limestone is divided into Marine deposit and Continental deposit Most of them are the former. According to its origin, limestone can be divided into biodeposition Three types, chemical deposition and secondary; According to the composition of the ore, limestone can be divided into Siliceous limestone , clayey limestone and Dolomitic limestone Three kinds. Resource distribution: China is rich in limestone mineral resources, which are used as cement, solvent and chemical industry Limestone deposit There are more than 800. Producing areas all over the country, provinces, cities and autonomous regions can be near the industrial area of local materials.

Limestone minerals in each Geological time There are deposits, which are distributed in various stages of geological structure development, but the limestone deposits with good quality and large scale often exist in a certain horizon. Take cement limestone as an example, northeast, North China Ordovician system Majiagou Formation limestone is a very important horizon, which is widely used in central, East and southwest China. Triassic system Limestone is commonly used in Northwest China and Tibet. Devonian system Limestone of East China, Northwest China and the middle and lower reaches of the Yangtze River Ordovician period Limestone is also an important bedding for cement raw materials.

Ore property

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limestone

1. The mineral composition of limestone is mainly calcite , accompanied by dolomite, magnesite And other Carbonate mineral Mixed with other impurities. The magnesium in it appears as ash and magnesite, Silicon oxide It is a form of dissociation quartz , stone and pulp opal Distributed within rocks, Aluminium oxide Synthesis by siliconization with oxidation Aluminium silicate (Clay, feldspar , mica); The compound of iron is carbonate (magnesite), pyrite ( pyrite ), free oxides ( magnetite , hematite ) and hydroxide (water goethite ) exist; In addition to glauconite There are coal, asphalt and so on in individual types of limestone Organic matter And plaster, anhydrite Etc. sulfate As well as phosphorus and calcium compounds, Alkali metal Compounds and strontium, barium, manganese, titanium, fluorine and other compounds, but the content is very low.

2. The nature of limestone

Limestone has good workability, polishing and very good cement Performance, insoluble in water, easily soluble Saturated sulfuric acid Can react with a variety of strong acids and form the corresponding Calcium salt At the same time release CO 2 . When limestone is calcined to more than 900 ° C (generally 1000~1300 ° C), it is decomposed into lime (CaO) and released CO 2 . Quicklime is deliquescent in contact with water and forms immediately Slaked lime [Ca(OH) 2 The hydrated lime can be adjusted after it is dissolved in water, and it is easy to harden in air.

Process characteristic

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Lime has excellent properties such as thermal conductivity, firmness, water absorption, air permeability, sound insulation, polishing, good cementation and machinability, and can be used directly run-of-mine Can also be deep processing applications.

Main use

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Limestone is an important industrial raw material in metallurgy, building materials, chemical industry, light industry, construction, agriculture and other special industries. With the development of the steel and cement industries, the importance of limestone is bound to increase further.

Quality standard

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limestone

The quality requirements for limestone vary according to its use. Generally speaking, metallurgy, chemical industry and other special Industrial sector antilimestone purity Requirement ratio Construction industry In addition to the development of the People's Republic of China professional standard ZBD60001-85 for the metallurgical industry, China has not developed national standards or professional standards for other industries, and the relevant standards are developed by the application departments themselves. Building materials industry Quality requirements for limestone products

(1) Cement industry: calcareous raw materials used in cement production, quality requirements are listed in Table 7. right amorphous Limestone, its granularity is required to be 30~80mm.

(2) Glass industry: in general, according to glass Limestone with different CaO content is selected for different quality requirements, but the limestone selected is required to be amorphous and the composition is stable.

Comprehensive utilization

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Comprehensive utilization Technical method China's limestone resources are characterized by large reserves and good quality. Therefore, the larger limestone mines in China all adopt the washing - crushing - grading method to treat limestone ore to remove the soil on the surface, sandstone The pollution of sticky mud to sand and stone. For lower-grade limestone or limestone with large differences in ore properties, some foreign countries use it Flotation method Or photoelectric beneficiation method. For example, the separation of limestone and quartz from iron by flotation method; By flotation or Photoelectric separation Carried out with limestone and dolomite magnesite The separation, etc.

Development and production

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lime

Calcined limestone to a temperature of 1000~1300°C, can be CaCO 3 CO in 2 Discharge, make quicklime . Lime is a white solid, refractory and insoluble, in the case of water heat absorption to produce hydrated lime, lime water saturated solution is alkaline, easy to CO in the air 2 The reaction produces CaCO 3 Settle. Commercially classified as high calcium lime (CaO≥90%), Calcareous lime (CaO≥85%), Magnesia calcium lime (MgO≥10%) and High magnesium lime (MgO≥25%) four categories.

Slaked lime

namely Calcium hydroxide ( Slaked lime )

Shi Fo

a. Molecular formula: Ca(OH) 2

b. Relative molecular mass : 74.08

c. Properties: fine white powder. Density 2.24g/cm 3 . Heated to 580°C, the lost water becomes calcium oxide, which absorbs CO in the air 2 And becomes calcium carbonate. Soluble in acid, glycerin, insoluble in water, insoluble in alcohol.

d. Application: Used in pharmaceutical, rubber, oil Industrial additive and Softened water Please wait. It is used in oil industry to add in lubricating oil to prevent coking, sludge deposition, neutralization and anti-corrosion.

e. Main raw materials and specifications: limestone (CaCO 3 ) ≥98%

f. Process and process flow: Lime digestion method is to calcined limestone in a calcining kiln Calcium oxide After that, the calcium hydroxide product is obtained by selecting, adding water to digest, and then purifying, drying and sifting. The reaction formula is as follows:

CaCO 3 =CaO+CO 2 (high temperature) CaO+H 2 O=Ca(OH) 2

The process flow is as follows:

Limestone and coke → roasting → selection → water digestion → precipitation → separation → drying → sieving → packaging → Calcium hydroxide

Calcium oxide

a. Molecular formula: CaO

b. Relative molecular weight: 56.08

c. Property: White amorphous powder. Density 3.25~3.38g/cm 3 . Melting point 2580°C. Boiling point 2850°C. It is placed in the air, absorbs water and carbon dioxide from the air, and generates Calcium hydroxide and Calcium carbonate . Calcium oxide Interaction with water (called "digestion") produces calcium hydroxide and gives off heat (the product is strongly alkaline). Soluble in acid, insoluble in alcohol.

d. Application: Calcium oxide is used in steel, pesticide, medicine, non-ferrous metal, fertilizer, leather, calcium hydroxide, laboratory Ammonia gas Drying and alcohol dehydration, etc.

e. Main raw materials and specifications: hydrochloric acid (HCl) 35%; Calcium carbonate (CaCO 3 ) 98%.

f. Process and process flow: calcium carbonate calcination method is to react calcium carbonate with hydrochloric acid to produce Calcium chloride , use Ammonia liquor Neutralize, filter, add Sodium bicarbonate The reaction produces calcium carbonate precipitation, which is obtained by dehydration and dry calcination. The reaction formula is as follows: CaCO 3 +2HCl→CaCl 2 +CO 2 +H 2 O

CaCl 2 +2NH 3 ·H 2 O→Ca(OH) 2 +2NH 4 Cl

Ca(OH) 2 +NaHCO 3 →CaCO 3 +NaOH+H 2 O

CaCO 3 →CaO+CO 2

The process is as follows:

Calcium carbonate plus hydrochloric acid → acid hydrolysis → neutralization with ammonia water → static precipitation → filtration → Reaction with sodium bicarbonate → Dehydration of calcium carbonate → drying → calcination → Screening → packaging → calcium oxide

Light calcium carbonate

a. Molecular formula: CaCO 3

b. Relative molecular weight: 100.08

limestone

c. Property: white powder, odorless, tasteless, density: calcite type 2.711g/cm 3 Nepheline type 2.93g/cm 3 . Melting point (110 atmospheres) 1289°C. Insoluble in water, alcohol, slightly soluble in containing Ammonium salt Or an aqueous solution of carbon dioxide, soluble in Dilute acetic acid , Diluted hydrochloric acid , Dilute nitric acid At the same time, carbon dioxide is released, showing an exothermic reaction.

d. Use: Mainly used in rubber, plastic, paper and other industries filler It is also used as a filler for paint and ink. Also used for toothpaste , welding electrode, organic synthesis, metallurgy, glass , asbestos, felt Such as production. It's also a neutralizer for industrial wastewater, stomach and duodenum Acidulant of canker disease, acidosis Antidote .

Main reaction: Ca(OH) 2 +CO 2 →CaCO 3 +H 2 O

Manufacturer: Sichuan Chongqing Songshan Chemical Plant, Guizhou An Thuan Glass chemical plant, Yunnan Kunming Chemical Plant, Gansu Lanzhou Baiyin District Chemical plant, Henan Province Jiaozuo Chemical Plant No. 3, Henan Mixian Chemical Plant, Hunan Hengyang Chemical Plant No. 3, Shanghai Xinjiang Chemical Plant, Shanghai Calcium Carbonate Plant, Jiangsu Yixing Lime Plant, Zhejiang Wuxing Linghu Chemical Plant, Anhui Anqing Chemical raw materials Factory, Shandong Zhangdian Hutian Chemical Plant, Shandong Zibo Luo Village Chemical Plant, Beijing Ore Materials Factory, Hebei Tangshan East Mine Chemical Plant and Liaoning Province Benxi Lime chemical plant, etc.

Heavy calcium carbonate

Commonly known as Solo pink , Double Fly Pink , three fly powder, four fly powder)

a. Molecular formula: CaCO 3

b. Relative molecular weight: 100.08

c. Properties: White powder, odorless, tasteless. There is no change in the exposed air, and the density is 2.71g/cm 3 . Melting point 1339°C. Almost insoluble in water, when containing ammonium salts or Iron sesquioxide Slightly dissolved in water, insoluble in alcohol. In case of dilute acetic acid, dilute hydrochloric acid, dilute nitric acid, bubble boiling, and dissolve. Heat decomposes into calcium oxide and carbon dioxide.

d. Use: press crushing fineness Different, the industry is divided into four different specifications: single, double, three, four, respectively, used in various industrial sectors.

Solo powder: Used in production Anhydrous calcium chloride It is an auxiliary raw material for sodium bichromate production, and the main raw material for glass and cement production. In addition, it is also used for building materials and poultry feed.

Double fly powder: raw materials for the production of anhydrous calcium chloride and glass, white fillers for rubber and paint, and building materials.

Sanfei powder: Used as filler for plastics, coatings and paints.

Sifei powder: used as wire insulation filler, rubber molding products and asphalt felt filler.

e. Main raw materials and specifications: limestone (CaCO 3 ) ≥90%

f. Process and process flow: Pulverized method will contain CaCO 3 More than 90% of the lime by grinding, grading, separation of the product. The process flow is:

Limestone → crushing → Grading → Cyclone separation → Heavy calcium carbonate manufacturer

Qingdao fertilizer Plant in Shandong Province and Shanghai Stone powder The factory, etc.

Development status

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limestone

Limestone is widely used and is an essential raw material for all sectors of the national economy and people's lives. Mainly used for: (1) in the construction industry for production cement And fired lime; (2) metallurgical industry used as a flux; (3) Used in the chemical industry to make alkali, Bleaching powder And fertilizer, etc.; (4) Used as a clarifying agent in the food industry; (5) Used in agriculture to improve soil; (6) Used as fillers in the plastics industry; (7) Widely used in the coating industry to make a variety of architectural coatings; (8) In Paper industry Used as alkaline filler; (9) Used as a basic filler for rubber in the rubber industry; (10) Used in the environmental protection industry adsorbent .

Heavy calcium carbonate is made from natural calcite, limestone and chalk As raw materials, mechanical grinding to reach a certain fineness of the product, its production methods have two kinds of dry method and wet method, foreign has made great progress in the wet grinding process is still blank in China; It's being produced with limestone Light calcium carbonate In the process, the particle size of the light calcium product is compared with Crystal form In terms of control, there is still a big gap compared with foreign countries. Therefore, it is necessary to further develop the deep processing industry of limestone in the future, broaden the application field, strengthen the comprehensive utilization, add value to the product and improve economic benefits.

Development trend

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Stone bench

Limestone is an important industrial raw material in metallurgy, building materials, chemical industry, light industry, agriculture and other departments. With the development of the steel and cement industries, the demand for limestone will further increase. Cement production is huge, that is, more than 100 billion tons of limestone need to be mined for cement products every year. It is predicted that by 2020, the national cement production will reach 300 million tons, which will require the mining of more limestone as raw materials. In addition, metallurgy, chemical industry and other aspects of the demand for limestone is also great. Therefore, the production and development prospects of limestone industry are broad, and in order to make limestone products have greater value-added benefits, the development of deep processing products of limestone is also a future development direction.

Collection information

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Geological Museum of China Collection Information:

Pictures of Limestone Collection of China Geological Museum (1)	Picture description : Photo of the specimen of the small Huangbaiyu Limestone in Benxi Qiaotou, China. Gray; Granular structure; Massive structure; The main mineral composition is calcite Collection unit : Geological Museum of China
Pictures of Limestone Collection of China Geological Museum (2)	Picture description: A photograph of a Limestone specimen in Yundu, China . Gray; Granular structure; Massive structure; The main mineral composition is calcite. Collection unit: Geological Museum of China

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