Quicklime: features and scope of application. Technical characteristics and properties of lime, area of its use and types Construction quicklime grade 1 manufacturer
Lime is a universal substance that, thanks to its extensive and varied properties, can be used in almost any field of activity. It happens various types, depending on the selection criteria, and is divided into several varieties. Options for preparing solutions containing it do not differ much from each other and do not cause difficulties, so this raw material can be used independently without the involvement of specialists.
Peculiarities
Quicklime is calcium oxide obtained by burning calcium carbonate and has a finely porous structure. Sometimes quicklime is called boiling lime.
Advantages over slaked lime
It has many advantages over the hashed variety:
- high strength;
- absorbs less moisture;
- work with this material can be carried out in winter;
- no waste;
- very wide scope of application.
Quicklime is dangerous to human health, so it is advisable to carry out work in an open space using protective equipment.
A good advantage of quicklime is its low cost compared to other mixtures. Lime material is resistant to temperature changes, it does not crack, and has antimicrobial properties.
Specifications
Lime is a substance that is often found in nature (mainly in rocks ah), and the manufacture of the product occurs in full compliance with established standards, because mixtures on such a basis must high level perform protective functions.
The finished lime should consist only of carbonate rocks (limestone) with a small clay content. Various additives and impurities are allowed in the composition of the material based on GOST standards, depending on the area of application.
Limestone is very similar in appearance to chalk or coke, but they have different properties and are not interchangeable. To distinguish limestone from chalk, you can drop water on them. Chalk will not give any reaction, but limestone will begin to foam and generate heat. If you use chalk to whitewash walls, it will leave marks on clothes and surfaces in contact with the wall. Lime does not leave any traces, so it is most often used for whitewashing walls.
Quicklime is divided into three grades (1, 2 and 3), and slaked lime is divided into 1st and 2nd grade. The exception is powdered quicklime; it is divided into two grades and has additives. Other types are produced without additives.
By external physical indicators, for example, by color, you can determine the type of material. After heat treatment limestone produces quicklime, and if it has white, this means that the material does not contain additives and is of a high grade. In other cases, the material has a grayish color, most often it is dolomitic and hydraulic lime.
The production of lime material consists of mining the rocks themselves, crushing them to the required sizes and then firing them in special kilns. Nowadays, shaft and rotary tube kilns are most often used because they provide uniform temperature exposure to the material and a continuous firing process.
The strength of the raw material is affected by the firing temperature and the production process itself. There are three options for the strength of the finished product: hard-burnt, medium-burnt and soft-burnt lime.
Soft-burnt lime is very popular in construction due to the following properties:
- the extinguishing process occurs quickly, within about 3 minutes;
- such material has small size and low density.
Lime belongs to a low hazard class, but safety precautions must be observed during transportation and storage. Since quicklime reacts violently with water, it is necessary to ensure that moisture cannot come into contact with the material.
The composition of lime most often includes various mineral additives that improve the properties of the material: granulated blast furnace slag, quartz sands and other substances.
Species
There are two types of lime, which are distinguished by the amount of calcium silicates and aluminoferrites they contain: air and hydraulic. They perform various functions, for example, air accelerates the hardening process of concrete, and hydraulic accelerates reactions in water.
It is important that all fragments of the substance are the same size. This moment indicates that the raw material has been completely calcined in the furnace. If pieces are too large or too small, they may not be completely heat treated, and this will reduce the quality of the finished material.
Based on the type of processing, there are several types of material:
- quicklime lump (boiling liquid);
- quicklime ground (powdered);
- quenched hydrate – Ca (OH) 2;
- lime dough;
- lime milk.
Lump lime
Lump lime is a mixture of lumps that differ in size. It contains calcium oxide and magnesium, as well as materials such as calcium carbonate, aluminates, and silicates. Magnesium or calcium ferrites, which are formed during firing of raw materials, can be added.
The good strength of concrete is ensured due to the fact that lump lime requires very little water (due to the fine grinding of the material) and produces virtually no waste.
Ground lime
Ground lime has the same composition as lump lime, but the difference is that the lumps of raw materials are ground much stronger and more thoroughly.
The main advantages of ground lime:
- strength;
- water resistance;
- fast hardening.
To increase or decrease the hardening rate, calcium chloride or sulfuric acid is often used (gypsum material is also suitable).
Hydrated lime
Hydrated lime (also called fluff) is a slaked type of material with a highly dispersed composition. Slaking occurs by adding water to the lime raw material. To prepare such a solution, add from 70 to 100% water to the powder.
In order for the lime to completely go through the slaking process, it must be placed in a special pit for 2-3 weeks. This way it will gain optimal strength and ductility. The minimum cancellation period is 36 hours. To prevent the raw material from burning out, it is advisable to add water gradually until steam stops being released.
Lime paste is formed when sufficient water is added to form plastic material. You can also find a solution such as lime milk (mainly used for whitewashing tree trunks). Lime milk is made by adding excess water to lime dough.
Types of compounds
Depending on the scope of application, the following types of compositions are distinguished:
- Construction lime– it is added for the preparation of concrete and cement mixtures in order to increase the strength of the composition;
- Hydraulic– also used for the production of concrete, but of low grades. Ideal for structures located in areas with high humidity;
- Komovaya– mainly used to prepare a solution for whitewashing;
- Sadovaya– used in agriculture as a soil fertilizer, treating plants from insect pests, protecting them from rotting and improving growth; it is highly undesirable to use it simultaneously with other types of additives and fertilizers;
- Sodium– used in the chemical industry and medicine;
- Chlorine– used as a disinfectant and for water purification.
Classification of lime by slaking time
- fast-extinguishing (up to 8 minutes);
- medium-extinguishing (up to 25 minutes);
- slow-extinguishing (from 25 minutes).
Types of puffed lime
Depending on the percentage of presence of magnesium oxide in the composition, the following types of air lime are distinguished:
- calcium;
- magnesia;
- dolomite.
Scope of application
Lime is used in many areas.
- In agriculture, lime is used to control pests, reduce soil acidity, prevent the appearance of fungus, additionally feed animals, improve land cultivability, and replenish calcium and phosphorus. It is best to treat heavy soil with quicklime. Lime is widely used as a material for whitewashing trees and treating plants.
- Construction. It is used to accelerate the hardening of cement and impart plasticity to the composition; it is involved in the production of thermal insulation materials and dry building mixtures, serves as a connecting link in building structures.
- Ferrous metallurgy – enriches ferrous and polymetallic ores.
- Chemical industry - used in paint, perfume and pharmaceutical industries. Used as a reagent and as a neutralizer for acid sludge.
- Pulp and paper industry.
- Textile industry.
Chlorinated lime is used for disinfection and cleaning of public places, as it has disinfecting properties. Quicklime is even used in the food industry for mixing substances, and milk of lime is used to make sugar. Soda lime is used in medicine (artificial ventilation or for anesthesia) and for respiratory systems (scuba tanks, respirators and other devices).
Lime mortar coating wooden surfaces protects them from rotting processes and fires.
How to use?
When preparing lime mortar, it is important to ensure safe interaction of raw materials with water for humans. It is advisable to carry out work in a well-ventilated area, or better yet, in an open space. Since the substances used are chemicals, it is necessary to adhere to safety rules when working with such materials.
The powder substance can be used in both dry and liquid form. To prepare a liquid solution, the powder is poured into a container and filled with water. The solution must be mixed and diluted to the required consistency.
To whitewash trees, the raw material is diluted with water and applied to the tree trunk using a wide brush. But due to the liquid consistency of the solution, you will have to process the barrel several times. In order to reduce work time, you can add clay, milk, or PVA glue to the solution. These ingredients will make the mixture thick and viscous, and it will lie evenly on the surface. Before processing the tree, you need to remove all dead layers of bark without damaging the trunk.
To protect plants from fungus, you can use soda ash instead of lime, because soda dissolves faster and completely in water.
Do not over-work the soil a large number lime, since it will become alkaline, which will also not contribute good growth and plant development. You cannot use manure and lime at the same time, because such a combination will interfere with the formation of useful substances.
Before using bleach, you need to check the reaction of the surface. To do this you can process small area, and if it remains intact after about 10 minutes, then you can use bleach on the entire surface. First, water is added to the raw material in a small amount and mixed until it becomes sour cream, and then more water is gradually added, also stirring, until a liquid solution is formed. In dry form, bleach is used only on damp surfaces.
In construction, it is recommended to use quicklime ground lime for the manufacture of plasters, slag concrete, and painting elements. In other cases, slaked lime is used, which, due to its moisture resistance, prevents the formation of mold.
Fluffy has wide scope Applications: from domestic needs to construction. To prepare the fluff, you need to pour the raw materials into a rust-free metal container (or a plastic one) and gradually add water, stirring the solution. Once the mixture is ready, you need to leave it to brew for several hours or days. The longer it stands, the higher its quality and strength indicator will be.
- If you need to store the prepared lime mortar for a long time, you can periodically add water to it. Initially, water is added until the material no longer absorbs it. This rule does not apply to the preparation of lime milk.
- The optimal depth for digging lime into the soil is 20 cm, but if the dose of fertilizer is small, then the depth should be less. The lime is covered with a layer of sand on top. For storage in winter time It is recommended to pour another layer of soil 70 cm high on top of the sand layer.
- Before applying to any surfaces (wood, concrete, cement, metal), it is necessary to completely remove dirt, grease, defects, and rust from them.
- It may happen that lime gets on unnecessary area and it should be washed off. To do this, first of all, it is necessary to moisten this area generously, wait for the lime to dissolve well, and then remove the material using a hard metal sponge. If necessary, these steps should be repeated. There are already ready-made solutions for such needs on sale, for example, Guard Industrie or “Probel”. Can also be used homemade solutions based on hydrochloric acid.
- It is not recommended to apply a primer before whitewashing, as the lime will not adhere to such a base. It is also advisable to whitewash with brushes rather than with a spray gun. The brush will distribute the lime mortar better, and the finish will be of better quality.
- The longer the holding period ready mixture, the better it will perform its functions.
- To prepare mortars, it is best to add sand.
- This material is not suitable for making cement for fireplaces or stoves, as carbon dioxide is released when heated.
- To obtain insulation, you can add sawdust and gypsum to the fluff. In other cases, the lime mortar should not contain sawdust, lumps or other inclusions in order to cover the surface evenly and completely.
Construction materials produced and put on the market must comply with certain technical and quality parameters, which are created and regulated at the state level.
To achieve these goals, GOST standards are created, each of which describes the main characteristics of the selected building material and standards for compliance. Construction lime is regulated by GOST 9179 77. The technical act establishes the specifics of this material.
As you know, it is a product of firing rock composed mainly of natural elements or its mixture with special components of mineral origin.
Classification and characteristics of construction technical lime
The white substance obtained by burning limestone is separated depending on the solidification conditions. This is how it happens:
- with elements of air. Provides hardening of mortars for construction and concrete, while maintaining their original characteristics. proportions of cement-lime mortar for plaster;
- with hydration with components. They ensure the hardening of construction materials concrete solutions, while retaining their original strength regardless of the environment. proportions cement mortar. It can be air or water.
In turn, there is a classification of quicklime with air layers, depending on the percentage of calcium and magnesium oxide that it contains.
It goes on the market:
- with calcium components;
- with magnesium components;
- with dolomite components.
Lime with air layers can be divided into those that are not slaked and hydrated (slaked).
The latter is obtained by quenching the components discussed above. The hydraulic white substance that is obtained by burning limestone can be divided into:
- weakly hydraulic;
- highly hydraulic.
According to the structure of the fractions, lime, which corresponds to GOST 9179 77, is divided into:
- lumpy;
- crushed;
- powdery.
Powdered material is obtained by crushing and grinding, and then quenching the lump of potassium oxide. Ultimately, a chemical mineral component may be added to the mass.
The unslaked white substance obtained by burning limestone is classified according to the degree of slaking.
Lime is divided into those that are slaked very quickly - no longer than 8 minutes, at an average pace - from half an hour, very slowly - more than half an hour.
Quality control
Potassium oxide is controlled by the department that is responsible for technical control. It is created in every company. Happening acceptance and shipment of material in batches, while their size depends on the productivity of the enterprise for 12 months.
Quantity measured:
- two hundred tons - with a productivity of up to one hundred thousand;
- four hundred tons with a productivity of one hundred thousand to two hundred and fifty thousand;
- eight hundred tons – from two hundred and fifty thousand;
Reception and unloading of batches and smaller masses can be carried out. The mass of the material supplied must be determined by weighing the lime in transport using a special device to determine it. Such devices can be of railway or automobile type.
Mass material that is shipped in ships, easily determined by shrinkage. Acceptance and certification of goods is mandatory. The type and type of potassium oxide is indicated based on information provided by the company's process control department.
Magazines with information on flow control that are used when receiving goods must be numbered and sealed accordingly by the enterprise.
Technological control of all production stages carried out at the plant is carried out in accordance with special regulations.
Current quality control of goods that are shipped is carried out according to information from testing data from general samples, which are compiled during the work of several shifts. Materials for the sample are selected.
Lump lime is from equipment that regulates the supply of goods to warehouses. The total sample taken is no more than two tens of kilograms. For material in powder form - from each place of production, with a total sample of ten kilograms.
Disposable materials for tests are selected evenly and in equal quantities. General tests of lump material should be crushed until centimeter particles are formed. The samples that are taken for in-line control of the batch that is shipped are thoroughly mixed.
Then they are divided into equal parts. Some of them are necessarily tested to determine standard indicators, others are placed in a vessel where air does not enter. It is immediately sealed and stored in a room with low moisture concentration in case control tests are carried out.
A control test to determine the quality of the material is carried out by special inspections. They can be both state and departmental. It can be carried out by the consumer himself if he has the appropriate skills and strictly follows the sampling procedure.
An element is selected from each batch for testing, which is obtained by combining and thoroughly mixing all collected materials.
For lump lime for tests it is worth collecting three dozen kilograms, for powdered form - half as much.
When all the lime is shipped simultaneously, the material for study is selected at the loading or unloading stage. In the latter case, it is taken from the bags, or already at the unloading stage, when the buyer begins to use it.
If the material in question is supplied in bulk on special trains, a sample is taken in equal parts from each car. If potassium oxide is delivered by car, the test is collected in equal parts from all containers that exceed thirty tons.
If potassium oxide is supplied in bags - in equal parts from ten bags, which are selected at random. If potassium oxide is supplied by ship, from a conveyor belt or other loading and unloading mechanism.
When the material for the general test is selected, it is being studied to determine the indicators provided for GOST 9179 77. At the quality test stage, potassium oxide must comply with all the norms of the described standard.
Trial
Chemical studies and determination of physical and mechanical characteristics of potassium oxide are carried out according to the prescribed standards in GOST 9179 77. Lump material is shipped in bulk.
Lime in powder form is shipped in bulk or sorted into special containers. If the client agrees, the use of paper bags with four layers of paper is allowed.
To determine the average gross tare weight, twenty bags are weighed at the same time and selected at random. The resulting number is divided by 20.
The average net tare weight is determined by subtracting the average net number of the bag from the gross number.
It is allowed to deviate from the average values of bags of net lime from those indicated on the container. This number cannot exceed one thousand grams.
The manufacturer, at the same time, with the details and information for shipment, must convey to each buyer the quality control asport, where it must be indicated:
- at what enterprise the product was manufactured;
- when the potassium oxide was shipped;
- party and passport number;
- weight of goods sold;
- when was the extinguishing carried out and at what temperature;
- how many minerals and other elements were added;
For each transported unit, a label is inserted, which states: the name of the company, the name of the product, its guaranteed type and grade, a description of the standard according to which the delivery is carried out.
If the material is shipped in paper containers, it must indicate:
- what is the name of the company;
- what is it called product, type and grade;
- description of the standards according to which the delivery is carried out.
The manufacturer must deliver the goods by transport, while preventing moisture from entering. Ingress of moisture is undesirable when storing materials.
Potassium oxide can be transported regardless of the type of covered transport in accordance with the standards for transporting such substances that apply to it.
GOST 9179 77
Today, the material in question, which can be extracted by firing, is actively used as the basis of cement. This became available due to the material’s ability to perfectly absorb moisture.
This material is in demand at the stage of production of slag concrete components, products with coloring pigments, and white bricks. its size. Quicklime is also used for decorative plaster. you can see its application.
Quicklime is actively used to neutralize waste water, for the treatment of buildings.
It can be found in most products on the market. food products. It is hidden in the form of substances that ensure the creation of emulsions from immiscible liquids, binding components that, due to their chemical and physical properties, resist dissolution in each other: for example, liquid and oil.
Quicklime has the following technical characteristics. its formula. Potassium oxide manufactured in accordance with GOST standards in accordance with technological regulations, which is approved in the manner established by regulatory legal acts.
Materials that are used at the production stage of potassium oxide: sedimentary rocks consisting of carbon dioxide salts, inorganic natural and artificial materials with hydraulic and (or) pozzolanic properties. All these components must comply with GOST 9179 77.
Construction lime and its technical specifications also discussed in this document. Quicklime with air gaps without the addition of other foreign elements is divided into three types. about application.
Quicklime in powder form with different mineral components - into two grades; hydrated (slaked) without and with special additions - into two grades. its formula. Hydrated potassium oxide cannot be wet, this figure is 5 percent. The type of potassium oxide is determined by its indicative components, which correspond to low grades.
The percentage of hydration water in the quicklime type material cannot be more than two percent, and the maximum particles of crushed material cannot be more than 2 cm.
For more information about quicklime, watch the video:
Slaked lime (also called hydrated lime) is produced by contacting it with water. about its application.
It, in turn, completely changes the chemical and physical characteristics material, which releases excessive heat in the form of steam. If you pay attention to the type of slaking, the result can be: lime water, milk or fluff.
Application
Lime GOST 9179 77 is used:
- in fertilizers. They have been used for many years to increase soil fertility and for liming, in other words, reducing the degree of acid content. Lime fertilizers hard rocks crushed before adding to the soil;
- when whitewashing wall and flooring. Completely different proportions are already used here, a kilogram of lime is diluted with two liters of water. If necessary, you can add a little more water until you reach the desired consistency.
Conclusions
Lime at the production stage must comply with all technical features, which are prescribed in GOST. Otherwise, it will not pass the testing stage, quality control and will never enter the market.
The material is actively used in or for the manufacture of elements with a connecting texture and building parts. In GOST 9179 77, hydrated lime is classified and considered depending on its typology and properties.
The chemical composition of lime may vary slightly. By percentage Calcium silicates and aluminoferrites contained in lime are of two main types:
- air lime. This type of lime allows mortars to harden under normal humidity conditions;
- hydraulic lime. Such lime ensures the hardening of solutions used both in air and in water.
For air lime, the typical amount of calcium silicates and aluminoferrites is usually 4-12%, in rare cases up to 20%. Lime with a percentage of clinker minerals of 25-40% is called weakly hydraulic because it exhibits weak hydraulic properties. Highly hydraulic lime contains from 40% to 90% calcium silicates and aluminoferrites.
Lime is also classified according to the type of basic oxide contained in airy lime. There are three types of lime:
- calcium lime;
- magnesian lime;
- dolomitic lime.
Calcium lime contains 70-96% CaO and up to 2% MgO.
The composition of low-magnesium lime consists of 70-90% CaO and 2-5% MgO. Magnesia lime contains MgO in the range of 5-20%, dolomite lime - 20-40%.
Further, depending on the methods of further processing of the burnt product, several types of air lime are distinguished:
- quicklime lump lime- boiling water, consisting mainly of Ca(OH);
- quicklime ground lime- powdered product of grinding lump lime;
- hydrated lime (slaked)- fluff - fine powder obtained by slaking lump lime a certain amount water and consisting mainly of Ca(OH);
- lime dough- a pasty product of slaking lump lime, consisting mainly of Ca(OH) and mechanically mixed water;
- lime milk- a white suspension in which calcium hydroxide is partially dissolved and partially suspended.
According to the slaking time, all varieties of pneumatic quicklime are divided into three groups:
- fast-extinguishing- extinguishing time no more than 8 minutes;
- mid-life- extinguishing time no more than 25 minutes;
- slow-burning- extinguishing time is at least 25 minutes.
Powdered lime, obtained by grinding or slaking (hydration) of lump lime, is divided into: lime without additives and with additives.
Properties and technical specifications
Lime intended for the construction industry is produced in accordance with the requirements of state standards according to certain technological regulations.
To produce building lime, the following components are required: carbonate rocks, mineral additives (granulated blast furnace or electrothermophosphorus slag, active mineral additives, quartz sands). All additives must meet the requirements of the relevant applicable regulations.
The division of lime into grades is carried out as follows: airy quicklime without additives is divided into three grades (1, 2, 3); quicklime powder with additives - into two grades (1, 2); hydrated (quenched) without additives and with additives for two grades (1, 2).
Requirements for airborne lime.
Norm for lime,%, by weight |
||||||||
quicklime |
hydrate |
|||||||
Indicator name |
calcium |
magnesian and dolomite |
||||||
ActiveCaO + MgO, not less: |
||||||||
no additives |
||||||||
with additives |
||||||||
Active MgO, no more |
||||||||
CO2, no more: |
||||||||
no additives |
||||||||
with additives |
||||||||
Unquenched grains, no more |
||||||||
Notes:
1. The MgO content for dolomite lime is indicated in parentheses.
2. CO2 in lime with additives is determined by the gas-volume method.
3. For calcium lime of the 3rd grade, used for technological purposes, the content of unslaked grains is allowed, by agreement with consumers, no more than 20%.
The moisture content of hydrated lime should not be more than 5%. The grade of lime is determined by the value of the indicator corresponding to the lowest grade, if according to individual indicators it corresponds different varieties.
Requirements for chemical composition hydraulic lime.
Ultimate strength of samples, MPa (kgf/cm2), after 28 days. hardening must be at least:
a) when bending:
0.4 (4.0) - for weakly hydraulic lime;
1.0 (10) - for highly hydraulic lime;
b) during compression:
1.7 (17) - for weakly hydraulic lime;
5.0 (50) - for highly hydraulic lime.
It is permissible to determine the type of hydraulic lime by its compressive strength if, according to certain indicators, it belongs to different types.
The content of hydrate water in quicklime should not be more than 2%.
The degree of dispersion of powdered air and hydraulic lime must be such that when sifting a lime sample through a sieve with mesh No. 02 and No. 008 according to GOST 6613, respectively, at least 98.5 and 85% of the mass of the sifted sample passes. Maximum size pieces of crushed lime should be no more than 20mm.
Air and hydraulic lime must withstand the test for uniformity of volume change.
The scope of application of lime is extremely wide - lime has been involved in many technological processes for several thousand years. Technologies are developing, bringing lime and its derivatives into an ever wider production horizon. Consumers of lime include the ferrous metallurgy, construction industry, pulp and paper industry, chemical industry, sugar industry and agriculture. Lime is also used in significant quantities to protect environment(neutralization of wastewater and flue gases).
The Samara plant "Strommashina" produces equipment and assembles with its equipment complexes for firing and. We can offer both rotary kilns and shaft kilns. In order to determine in which type of kiln it is more correct and profitable to burn limestone to produce lime in your particular case (be it construction or metallurgical), we advise you to read the article “”, or (what is even more correct) contact our contact managers data from the "" section of the site. We will definitely help you.
is a white crystalline substance. Belongs to the basic oxides, reacts with acid oxides and acids, forming salts. Dissolves in water with the release of energy, forming calcium hydroxide.Density 3.37 g/cm³. Melting point 2570° C, boiling point 2850° C.
Lump quicklime is an intermediate product. If it is used in slaked form, it is first processed into hydrated lime (fluff) or into lime paste.
Chemical Formula: CaO
In industry, calcium oxide is obtained by thermal decomposition of limestone (calcium carbonate) or by thermal decomposition of calcium hydroxide and calcium salts of certain oxygen-containing acids.
Classification of lime.
Construction lime, depending on the hardening conditions, is divided into air lime, which ensures the hardening of mortars and concretes and their preservation of strength in air-dry conditions, and hydraulic lime, which ensures the hardening of mortars and concretes and their preservation of strength both in air and in water.
Airy quicklime, depending on the content of calcium and magnesium oxides in it, is divided into calcium, magnesium and dolomite.
Air lime is divided into quicklime and hydrate (slaked), obtained by slaking calcium, magnesium and dolomite lime.
Hydraulic lime is divided into weakly hydraulic and strongly hydraulic.
Based on its fractional composition, lime is divided into lump lime, including crushed lime, and powdered lime.
Powdered lime, obtained by grinding or slaking (hydration) of lump lime, is divided into lime without additives and with additives.
Based on the slaking time, construction quicklime is divided into fast slaking - no more than 8 minutes, medium slaking - no more than 25 minutes, slow slaking - more than 25 minutes.
Application of quicklime.
The main volumes are used in construction as lime cement; when mixed with water, calcium oxide turns into hydroxide, which then, absorbing carbon dioxide from the air, hardens strongly, turning into calcium carbonate. However, at present, they try not to use lime cement in the construction of residential buildings, since the resulting structures have the ability to absorb and accumulate dampness.
The use of lime cement when laying stoves is strictly prohibited due to thermal decomposition and the release of asphyxiating carbon dioxide into the air.
Also finding some use as a readily available and inexpensive refractory material is fused calcium oxide, which has some resistance to water, allowing it to be used as a refractory where the use of more expensive materials is impractical.
Calcium oxide is also used in small quantities in laboratory practice to dry substances that do not react with it.
It is registered in the food industry as a food additive E-529.
| Indicator name | Norm for lime,%, by weight | |||||
| calcium | magnesian and dolomite | |||||
| 1st grade | 2nd grade | 3rd grade | 1st grade | 2nd grade | 3rd grade | |
| Active CaO + MgO, not less: no additives with additives |
90 65 |
80 55 |
70 3/4 |
85 60 |
75 50 |
65 3/4 |
| Active MgO, no more | 5 | 5 | 5 | 20 (40) | 20 (40) | 20 (40) |
| CO 2, no more: no additives with additives |
3 4 |
5 6 |
7 3/4 |
5 6 |
8 9 |
11 3/4 |
| Unquenched grains, no more | 7 | 11 | 14 | 10 | 15 | 20 |
1. The MgO content for dolomite lime is indicated in parentheses.
2. CO 2 in lime with additives is determined by the gas-volume method.
3. For calcium lime of the 3rd grade, used for technological purposes, the content of unslaked grains is allowed, by agreement with consumers, no more than 20%.
Packaging, transportation and storage.
Lump lime is shipped in bulk, powdered lime - in bulk or in paper bags. Four-layer paper bags can be used.
Lime is transported by covered transport of all types in accordance with the cargo transportation rules in force for this type of transport. It is permitted, with the consent of the consumer, to supply lump lime in all-metal gondola cars and open vehicles, provided that its quality is maintained and the necessary measures are taken against spraying and exposure to precipitation.
During transportation and storage, lime must be protected from moisture and contamination by foreign impurities.
Lime should be stored and transported separately by type and grade.
The guaranteed shelf life of the product is 30 days from the date of its shipment to the consumer.
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