78. Building lime

In the production of building materials and as raw material for processing of some surfaces is widely used lime. Lime produced by calcination in special furnaces equipped with a temperature of 1000 to 1200 degrees carbonate rocks. Thermally treated lime takes the form of irregularly shaped pieces that are in the process of further use is subject to various processing.

Chemical composition formula and lime

For lime production does not apply any chemical catalysts, the main condition for its receipt, only the respective thermal regime. This is produced in the manufacturing process is completely natural material, it permitted content of impurities of small lime clay.

Limestone, CaCO3 formula has, as is predominantly calcium. In the process of temperature influence the carbon dioxide is released and produced raw materials has the formula CaO.

Razgashennaya lime can be in several states:

• fluff or a fine powder obtained by mixing lime with water, the pieces, and the moisture percentage should be from 60 to 70%.

• lime dough - a starting material compound with water, it takes about 3.5 times greater. As a result of such cancellation, a dense mass that is used in various fields.

• If lumps dissolve lime with water in the ratio of 1:10, it is possible to obtain lime milk. This slaked lime used for whitewashing the interior of buildings, facades, household outbuildings.

• When slaked lime for a long time is not used, the process is reversed, ie, the solution absorbs carbon dioxide and hardens. On sale you can often meet lime - hydrated lime or lumpy.

Technical properties

For the production of quicklime and quicklime special requirements regulated by the state standard (GOST 9179-77):

1) In the production of lime is used only carbonate rocks and some mineral supplements. The amount of additives should not exceed the amount specified in the standards for certain varieties of lime.

2) Quicklime divided into three classes and should not contain additives, powdery additives available in two varieties, slaked may or may not have additives, and is distributed in two classes.

3) calcium lime is calcium the main component, MgO percentage should not exceed 5.

4) Dolomitizirovanayaya lime contains up to 20% MgO

5) Dolomite 40% MgO.

6) In the hydraulic may include silica, iron oxide, a small amount of clay.

            lime properties are defined primenyamymi during firing rocks and by the manufacturing process. As a result of the heat treatment furnace limestone out solid pieces quicklime depends on the color additives present, shade whiter than the higher grade material. Dolomitic lime and hydraulic grayish ottenok.Pri have contact with water releases carbon dioxide and lime becomes liquid, the concentration of which depends on the amount of water. Depending on the process and the firing temperature can be obtained by varying the strength of lime - firmly deification, intermediate variant and softly deified.

Stamps and some types of lime

Lime and divided by grades and primary raw materials used.

View and lime and the main brand is defined by its scope:

• Construction of lime produced from calcium and magnesium species. Apply lime building for administration as a plasticizer in the concrete mixtures, solutions. Building lime comes in lumps, in the form melkoypushonki or lime putty.

• Hydraulic lime - calcine limestone containing from 6 to 20% clay impurities. This kind of use of lime for the production of concrete of low marks, as a par with high strength, it has a low ductility. Hydraulic lime is often used in the construction of buildings, operation of which involves finding in a moist environment.

• lump lime is a semi-finished product used for the manufacture of powdered raw materials or solutions. The lumps of lime stored in closed warehouses, protected from humidity. Lump lime is marketed for the preparation of solutions for whitewashing.

• Gardening lime needed for the enrichment of acidic soils. In acidic soils minimum calcium content, which leads to poor growth and development of plants. Introduction of hydrated and quick lime in the soil is carried out in the spring or autumn, and preferably during the rainy season, so the limestone is more soluble. Do not make use of lime along with other fertilizers, and during operation is required to protect the eyes and hands.

• sodium (soda) limestone - porous white mass, which is a mixture of sodium hydroxide and hydrated lime. Soda lime is used as an absorber of carbon dioxide and moisture from the air. It is used in chemical laboratories for the production of gas masks, diving equipment. In medicine, used as a sorbent for anesthesia devices and hyperbaric chambers.

• Bleach is obtained in the course of a complex combination of free chlorine and calcium hydroxide. Bleach has strong disinfectant properties, previously used in its pure form in health care facilities. Today, chlorine is used for disinfection of latrines, cesspools, for the production of solutions for disinfection. Bleach has and bleaching properties.

Production and manufacturing technology

Lime production generally consists of two phases:

1) Quarry limestone and other rocks used. For the production of lime Komkova can use and waste production, using limestone for other purposes.

2) Roasting prepared rocks.

Limestone is mined in open pit quarries using explosives. Selective mining of rocks allows you to prepare the raw material, uniform in its density and chemical composition, which affects the quality of lime produced in the future.

Firing limestone - the main stage of the process of manufacturing an air lime. Depending on the impurities content and use different temperature conditions. All technological conditions must be met, as the limestone burned leads to low quality characteristics of the material. Dead burned lime is poorly soluble in water, has a high density and a negative impact on concrete solutions.

Calcination of the starting material is carried out in different furnaces. Widely used shaft furnaces, they are characterized by a continuous cycle of operation, efficiency, ease of management. Rotary kilns myagkoobozhennuyu allow to obtain the highest quality lime.

Developed and used by installation allows for the firing of the material in a fluidized bed or in suspension. Such systems make good use of the firing of the smallest fractions of rocks, but they have low efficiency.