Refractory brick: characteristics, sizes, types. Fireclay refractory for furnaces

Construction of chimneys, industrial stoves, fireplaces and other stone structures operating under the influence of high temperatures occurs using special materials. The use of conventional ceramic or silicate stone in such structures is unacceptable, since there is a possibility of its destruction. Specialists use refractory bricks, the masonry of which occurs with the use of the same thermally stable solutions. Heat resistance of the material is achieved due to roasting and the use of special components in the production of stone.

Characteristics

Brick refractory characteristics is different from conventional artificial ceramic or silicate stone. Part of the material is white clay, and the properties and types of bricks depend on impurities . However, they all have one category - refractories, that is, the ability to maintain their original characteristics when exposed to high temperatures that exceed 1580 degrees.

They are used mainly in industry, therefore, the production of refractories is subject to high demands. Since any refusal to operate such materials is fraught with large losses, not only temporary, but also financial. The main thing is that they provide security. Refractory brick is fire insulating material.

General characteristics of fire-resistant artificial stones:

• Low thermal conductivity - the ability to keep the heat inside the thermal units.
• Heat resistance - preservation of the strength of bricks when exposed to temperatures over 1580 degrees.
• Thermal inertia - the ability of refractory material to slowly cool down and quickly heat up.
• Heat capacity is a characteristic that ensures the accumulation of heat by brick for further yield.
• Chemical resistance to hot gases, slag, metal.
• The consistency of volume, that is, the characteristic of refractory stones, does not shrink or grow in the range from 0.5% to 1%.

Application

Refractory brick, the characteristics of which are different from ordinary masonry materials, found its application in the construction of thermal units. In the metallurgical industry for melting iron, nickel, copper, the temperature is above 1500 degrees, so the furnaces in such production are lined exclusively from dolomite, dinas, chromium-magnesite brick. Dinas stone is used for arches and lining of furnaces working with acidic substances. It expands at the temperature, but the magnesite refractory is compressed, so the arch with the use of the latter can collapse. That is, each kind of this category of brick has different properties and uses.

In the nonmetallurgical industry, the refractory stone is used for the laying of chemical production equipment, municipal boiler houses, coke kilns; Aggregates of glass plants.

Kinds

Refractory brick is available in four designs. Carbon type is made from coal tar with the addition of coke / anthracite powder. Such material is heat-resistant and slag-resistant. As a rule, it is used in the construction of blast furnaces. However, for its protection, another layer of fireclay articles is laid out. Dinas (quartz) stone is made of quartz powder and lime milk. The refractoriness of this material is 1730 degrees, and brick is used for laying equipment that comes into contact with acidic media.

Magnesite, chromite, chromium-magnesite brick is made of burned minerals. Also there are carborundum and graphite products. Refractoriness of such species is from 1500 to 2000 degrees.

Alumina is a popular material in the industry - fireclay refractory bricks. In its composition more than 30% of aluminum oxide (alumina) and the obligatory presence of special clay, resistant to temperatures. Refractoriness - up to 1400 degrees.

Classification by chemical properties

Depending on the composition of the main components, artificial stones can be divided into 3 groups: neutral, basic and acidic.

To the acidic group of stone materials are dinas and quartz-clay brick. They, without prejudice to themselves, interact with acidic media.

With alkaline medium, basic refractories are contacted without problems from dolomite, magnesite, chromomagnesite. They are used for the laying of thermal units, which require a sharp change in temperature in their work.

The neutral group for chemical compatibility includes fireclay refractory brick , carbon and graphite stone material. They are resistant to both alkaline and acidic environments.

Dimensions of products

Combine all types of refractory bricks under one universal size is impossible. Each type of product corresponds to its GOST, according to the requirements of which the construction material is made and where its main parameters are determined. In addition, the dimensions of the refractory brick depend on the shape, which is not always rectangular. This is due to the complex design of the thermal unit, which requires arches and arches.

For example, the sizes of rectangular single products begin with 230x65x65 mm and end with parameters in 345x150x75 mm. All dimensions of rectangular, wedge-shaped, hanging and other refractory products can be viewed in GOST 8691-73.

Marking

To answer the question of which one to purchase Refractory brick for the furnace, the price of which directly depends on the material values, it is necessary to know the basic marking of the product. Each block has a legend. The first letter denotes the name and type of the product. So, if the label contains the letter "Sh", then this refractory belongs to the group of chamotte stones; "D" - Dinas, "M" -mullite.

The second letter determines the maximum temperature of application of the material. Example for chamotte stones:

• SHA, SHAKE - 1400 degrees.
• SB - 1350 degrees.
• ШУС, ШВ - 1250 degrees.
• PB (semi-acid type) - 1350 degrees.
• MF - 1250 degrees.

The dimensions of the refractory brick are identified by the figure preceded by the first two letters of the product brand. For example, the refractory SHA-5 has the parameters 230х114х65 mm, and ША-8 - 250х124х65. ШБ-22 characterizes the product in the form of a wedge end (trapezoid), the dimensions of such material are 230х114х65х55 mm. After the number in the marking followed by the letters, which are an abbreviation of the manufacturer.

Cost

For the construction of fireplaces, barbecue, ovens, refractory bricks are used. The price of the material depends on the brand, dimensions, design features and manufacturer. To compare prices for October 2015 for Ukraine and Russia, four types of popular fireclay bricks were chosen. When ordering a pallet, there are 350-360 pieces of bricks. The price is indicated for 1 pc.

• Rectangular shaped product SHA-5 in Russia is estimated at 39.9 rubles.
• Similar to the previous refractory, ShA-8, which is slightly larger, costs 47.9 rubles.
• ША-22 (wedge end): the price in Russia is 49 rubles.
• ША-45 (wedge end): the cost of the product in Russia is 41.2 rubles.

Which brick to choose for the furnace?

When constructing furnace devices, you can use a red brick of normal roasting, the standard dimensions of which are 250x120x65 mm. It should have clear edges, without chips, smooth edges and right angles. Otherwise the masonry will be fragile. In the event of a break, the brick must have a homogeneous structure, that is, be inside without cracks, voids and interlayers.

Zheleznyak - a sort of burned brick can be used only for the installation of furnace foundations, since it is difficult to bind to the mortar. Unbaked (scarlet) artificial stone, silicate, perforated and hollow bricks used for masonry stoves and chimneys are not allowed.

Refractory brick for the furnace, the price of which is several times higher than the red ceramic stone, is necessary for the lining of thermal units. That is, to create a protective shell, a refractory is used, which is applied to the furnace. Due to this, the heat flow created inside does not destroy the main walls of the furnace.

Solutions

Refractory brick for the furnace should be laid in the construction with the use of a homogeneous solution, which would firmly hold the masonry and harden in the required time. For domestic ovens a clay solution is used, which is prepared, depending on the fat content of the clay, with the addition of sand in proportions of 1: 1 or 1: 2. A prepared solution is considered to be a solution if the ball rolled from it does not crack on the contour when it dries out, but does not crumble when it is rolled onto the floor. If there is an excess of sand, then the ball falls apart, the crack gives the presence of a large proportion of clay in the solution.

When laying industrial equipment, the refractory brick is fastened together by means of muzzles - these are calcareous solutions intended for bonding refractory products.

For the laying of foundations of stove, it is recommended to prepare lime mortar in a proportion of 1: 2 - 1: 4. Cement mixtures are used to build the foundations of thermal aggregates exposed to water, for example, groundwater.

Masonry category

When erecting and repairing the thermal units, the brickwork of the refractory brick takes place according to the following requirements that determine its category:

• The maximum thickness of the seams from 0.5 to 1 mm corresponds to a particularly careful laying of the 1st category.
• Seams of 1-2 mm in size between bricks belong to 2 categories.
• Standard (ordinary) masonry is characterized by a thickness of seams up to 3 mm.
• The presence of a solution between bricks over 3 mm corresponds to a simple fire-resistant masonry.

Classes, grades of refractories, masonry category - all this information should be spelled out in the working documentation. If there is none, then the thickness of the seams for different structural elements is determined from the special tables.