refractory materials Archives - RS Kiln Refractory Bricks

Refractory materials are developing towards environmental friendliness, strong adaptability, and long service life. Rongsheng Refractory Materials Factory supplies refractory materials for kilns used in 5,000 t/d clinker production lines. Rongsheng Refractory Materials Manufacturer leverages its innovative capabilities in refractory castables while focusing on customer needs, aiming to provide high-quality, long-life refractory lining materials for high-temperature industrial furnaces. Contact Rongsheng for free solutions.

Refractory Lining Configuration for a 5,000 t/d Cement Clinker Production Line

This article focuses on the refractory configuration for a 5,000 t/d cement clinker production line. The cement firing system involves a complex chemical process from raw meal to clinker, going through stages such as preheating in the preheater, decomposition in the calciner, high-temperature calcination, and cooling. The refractory materials used in each stage must be adapted to this process.

(1) Preheater System

This system utilizes kiln exhaust gas to gradually heat the raw meal from ambient temperature in a suspended state to above 750°C before entering the precalciner system for decomposition. The amount of refractory material used in this system accounts for nearly two-thirds of the total refractory material used. Its thermal characteristics are:

60% of the fuel and the preheated raw meal are thoroughly mixed in the precalciner for flameless combustion. Wall and flue gas temperatures are generally controlled below 1000°C. The temperatures of the other cyclones, from the first to the fifth stage, are not higher than 450°C, 650°C, 750°C, 900°C, 1000°C, and 1100°C, respectively.
The preheater system calcines the material with virtually no liquid phase, resulting in minimal agglomeration and sintering, and therefore requires less refractoriness. Furthermore, the overall system temperature is relatively stable, requiring less thermal shock resistance from the refractory material.
The preheater system is a stationary device, but its size is relatively large, requiring insulation materials with low thermal conductivity to reduce the outer shell temperature.
Due to the complex shape of the preheater system, including cones, cyclone inlet and outlet diameter changes, thin feed pipes, and numerous measuring holes, it is more convenient to use on-site formed refractory castables in these areas.
When using raw materials and fuels with high alkali content, the refractory materials in the preheater must withstand not only high-temperature corrosion but also chemical attack from alkali metal oxides.

The aforementioned thermal environment generally determines the configuration of refractory materials for each stage of the preheater, and the following principles should be followed:

Refractory materials with low thermal conductivity, good insulation, and a working surface with sufficient strength and resistance to alkali corrosion should be used.
Castables should be used for sections with complex shapes and a large number of thin pipes, while alkali-resistant bricks should be used for straight tubes and regular sections.
Different materials should be designed for different sections based on the different temperatures of the cyclones and to save costs. For example, for the first and second stage cyclones, a combination of refractory and insulation considerations can be considered, and clay-based alkali-resistant refractory materials can be selected. For preheaters below the third stage, alkali-resistant materials capable of temperatures exceeding 1100°C should be used.
Anti-scaling castables should be used for the refractory castables from the fifth stage to the smoke chamber and below the calciner, as the surface is prone to scaling.

The following is a brief introduction to the selection and dosage of refractory materials for the preheater of a 5000t/d production line:

Alkali Resistant Bricks for Rotary Kiln — Alkali-Resistant Bricks for Rotary Kiln

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RK-H High-Strength Alkali-Resistant Bricks

Quantity: 569 tons

Performance:

Application Areas: Vertical ascending flues, cyclone tubes, and cones

High-Strength Alkali Resistant Castable — High-Strength Alkali-Resistant Castable

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High-strength alkali-resistant castable

Usage: 850 tons

Performance:

Construction method:

Application: Tops of preheater stages 1-4, irregular shapes, etc.

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High-alumina low-cement castable

Usage: 200 tons

Performance:

Application: Precalciner, fifth-stage drum

Anti-scaling castable

Usage: 112 tons

Performance:

Application Area: Kiln tail flue chamber

Calcium Silicate Board

Consumables: 156 tons

Performance:

Application area: All refractory linings

(2) Tertiary Air Ducts

Tertiary air ducts utilize high-temperature, oxygen-rich gases from the kiln head to guide the ducting channels of the precalciner. At temperatures of 800-900°C, these gases contain a large amount of clinker particles, which can severely erode and wear the refractory materials at the bends. Therefore, the system’s alkali resistance and wear resistance must be considered. High-strength alkali-resistant bricks and calcium silicate board are used in the straight sections, while high-wear-resistant castables and calcium silicate board are used in the irregular sections.

Currently, two types of tertiary air ducts are used: parallel ducts and V-shaped ducts. Parallel ducts are arranged almost parallel to the kiln, while V-shaped ducts are V-shaped, with a settling chamber and discharge gate valve located at the lower end of the duct.

Parallel ducts are simple in design, aesthetically pleasing, and require minimal investment. However, to prevent clinker particles from settling in the tertiary duct, higher operating air velocities are required, resulting in greater resistance in the tertiary duct. This higher air velocity also requires higher wear resistance from the refractory materials. The V-type duct is more complicated and requires a large investment. It also requires regular dust discharge from the discharge gate valve. However, the V-type duct can adopt a lower operating wind speed, so the system resistance is low, and the wind speed wear is small.

The refractory material usage and performance requirements are as follows:

RK-H High-Strength Alkali-Resistant Bricks

Usage: 140 tons

Performance: See above

Application: Straight sections of air ducts

Ultra-High-Strength Wear-Resistant Castable

Usage: 70 tons

Performance:

Application Area: Tertiary duct bends and gates

Calcium Silicate Board

Consumables: 17 tons

Performance: See above

Application Area: All refractory linings

( To be continued…)

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Aug 7 2025

Composition and Structure of Refractory Materials for Industrial Furnace Lining

Although there are many types of industrial furnaces, in terms of basic structure, they mainly include three parts:

① Heating system: including equipment systems that provide various heat sources to the materials in the industrial furnace. Such as: energy medium pipelines and equipment systems, power transmission system transformer equipment, etc.
② Industrial furnace body: This is the basic structure of the industrial furnace. Generally includes frame support structure, furnace structure, material conveying system, etc.
③ Smoke exhaust system: mainly includes flue, chimney, heat exchanger, and smoke exhaust auxiliary equipment etc.
④ Other supporting equipment.

Design of Industrial Furnace Lining Structure

The basis for completing the furnace construction material to the furnace lining structure when designing the industrial furnace furnace lining structure is a key procedure for achieving the purpose of the equipment process. kiln brick lining. Here, we mainly introduce the furnace lining structure with refractory materials as the main material. During the design process of furnace lining, the following aspects are usually needed:

(1) Reasonable furnace size. This is determined by the production process served by industrial furnaces, and the furnace size is subject to process requirements and the overall design of the equipment. The furnace size is the basic condition for the industrial furnace production process. The rationality of the furnace lining size directly affects the production of the entire process.
(2) Stable structural form. Due to the special purpose of industrial furnaces, the furnace lining is generally heated on one side. When the furnace lining is in such extreme temperature difference environment for a long time, it may cause structural damage, stress deformation, or form a melting state on the hot surface, the furnace lining structure will be greatly tested. Therefore, the stability of the furnace lining structure is a key indicator of the furnace lining design.
(3) Economic and effective material allocation.

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Inner Lining Structure of Industrial Furnace

Generally speaking, there are four main forms of the inner lining structure of industrial furnaces:

(1) Refractory brick lining.
(2) Amorphous refractory lining.
(3) Refractory ceramic fiber lining.
(4) Mix lining.

Refractory Brick Masonry

Refractory brick masonry is composed of refractory bricks and refractory mud. kiln brick lining is the most traditional and widely used masonry structure in industrial furnace body structure. When constructing or building an industrial furnace body structure with refractory bricks, first of all, refractory bricks and refractory mud should be selected according to the design or original structural requirements. Then the masonry structure is constructed according to the design drawings. Generally, masonry with refractory bricks is mainly used in the walls, furnace tops, furnace bottoms and pipelines in industrial furnace body structures.

Amorphous Refractory Lining

The so-called amorphous refractory lining means that the main material that constitutes the furnace lining lining is an amorphous refractory material. These amorphous refractory materials mainly include: refractory castables, refractory plastics, refractory spray coatings, etc.

When refractory castable is the main material of the furnace body structure, it is used for working layers such as the side walls, furnace tops, pipeline linings and outer bandages of the furnace body structure. It is also used as an insulation layer between the working layer and the furnace steel structure (such as the furnace shell).

Refractory plastic: In theory, refractory plastic can replace the function of refractory bricks on the main structure of various industrial furnaces. However, in practical application, you still need to study the following issues before making a decision.

① Type and form of furnace: is it a smelting furnace, reactor or heating furnace;
② Furnace structure: furnace top, side wall or bottom; construction thickness, whether there is heat insulation material; height and load condition of the furnace wall, etc.;
③ Operation status of the furnace: furnace temperature and its changes, whether the operation method is continuous or intermittent, whether the heated material is solid or liquid or gas, impact load in the furnace, etc.;
④Economics and construction conditions, etc. In actual industrial furnace furnace structures, refractory plastics are most commonly used in the furnace roof and furnace wall parts of the furnace body.

Refractory spray coating: Because spraying tools have the advantages of being able to be at any angle, anywhere, and forming any geometric shape. Therefore, in the furnace lining design of industrial furnaces, a lining formed by spray coating is often used.

Since the characteristics of spray coatings are basically the same as those of castables, they are also similar to those of castables in structural form. Its application parts in industrial furnace bodies include furnace walls, furnace tops, pipeline lining walls, thermal insulation layers, etc. In order to stabilize the structure of the spray coating lining, different forms of metal anchors or anchor bricks are usually provided in the lining according to specific structural requirements.

Refractory Ceramic Fiber Lining

Refractory ceramic fibers are loose as a semi-finished raw material and can be processed into finished products such as fiber blankets, fiber ropes, fiber paper, fiber boards, fiber fast-tipping (folding modules or laminated modules). After adding the binder, it can be used as a fiber spray coating or fiber castable. Ceramic fibers can be used directly in a loose shape. However, when it exists as a lining, ceramic fibers are often processed into blankets, plates, or blocks for use.

Therefore, in the lining of existing industrial kilns, it is essentially determined that refractory materials must be used to protect the melting changes of the shell. Based on the actual working conditions of each industrial kiln, a mixed body structure of a variety of refractory materials is generally used to extend the life of the furnace lining and save production costs for enterprises.

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Industrial Refractory

Nov 9 2020

The Characteristics of Refractory Materials for Hazardous Waste Rotary Kilns

Refractory bricks are built inside the hazardous waste incineration rotary kiln to protect the rotary kiln from direct hazards due to high temperature and corrosion during hazardous waste incineration. The properties of Refractory Materials for Hazardous Waste Rotary Kilns depend on the composition and distribution of their phases and the chemical characteristics of each phase. In other words, it depends on the chemical mineral composition and chemical composition in the hazardous waste rotary kiln.

high alumina brick — High Alumina Bricks

high class silica brick — High-Grade Silica Bricks

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Characteristics of Refractory Materials for Hazardous Waste Incineration Rotary Kiln

The main chemical components of refractory bricks used in general hazardous waste incineration rotary kilns include high alumina bricks, magnesia bricks, magnesia alumina bricks, and silica bricks. The content of Al₂O₃ in high alumina bricks is relatively high, generally around 70%. Magnesia bricks are mainly minerals composed of MgO and other metal oxides. Silicon bricks are mainly stable amorphous substances formed by SiO₂ and other metal oxides. Therefore, refractory materials for hazardous waste rotary kilns should have the following characteristics at the same time.

(1) High refractoriness. That is, high-temperature resistance, it needs to be able to operate in a high-temperature environment above 850°C for a long time without reaching the load softening temperature.
(2) Good wear resistance and flexural strength. The maximum stress that the refractory can withstand when it is bent on a 3-point bending device is required without breaking.
(3) Good chemical stability. To prevent the erosion and thinning of substances such as acid and alkali metals in the high-temperature flue gas. Relevant experimental studies have found that compounds of alkali metals (K, Na), halogens (F, Cl), and sulfur (S) are the main factors in the erosion and thinning of refractory materials.
(4) Good thermal stability. It can withstand the alternating thermal stress of the incineration state, and generally requires no less than 20 times of thermal shock resistance. That is, after heating and holding in a heating furnace at 1100°C for 15 minutes, the heated end is quickly embedded in flowing water at 5-35°C. After covering and cooling for about 3 minutes, take it out, observe the damage rate of the refractory brick, and calculate the number of times.
(5) The thermal expansion stability is better. Thermal expansion determines the expansion space reserved for refractory brick masonry. When the reserved space is insufficient, the refractory brick will explode and squeeze during high-temperature operation, resulting in an explosion. If the reserved expansion space is too large, the integrity of the rotary kiln may be poor. The middle gap is too large, resulting in non-integrity, and partial looseness, and may even fall off.
(6) The apparent porosity should be as low as possible. The apparent porosity refers to the ratio of the volume of all open pores in a material with pores to the total volume. Therefore, the higher the apparent porosity, the larger the volume of open pores contained in the refractory. The greater the probability of penetrating substances intruding into the refractory, the greater the erosion of the refractory, so the porosity needs to be controlled as low as possible. At present, domestically produced refractory bricks generally have a porosity of 20% and above.

Construction of Refractory Materials for Hazardous Waste Rotary Kilns

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Corrosion of Refractory Materials in Hazardous Waste Rotary Kiln

The materials entering the hazardous waste rotary kiln are mainly organic wastes such as industrial residues and chemical wastes. In the incineration process, the organic sulfur in hazardous waste undergoes high-temperature oxidation, mainly in the form of SO₃ and SO₂. The temperature of hazardous waste in the rotary kiln can reach 800~1300℃. In a high-temperature environment, SO₃ and SO₂ in the flue gas can easily react with minerals on the surface of refractory bricks to produce low-melting copolymers. The reaction equation of sulfur is as follows:

The corrosion of these low melting point polymers leads to serious loss of the bonding strength of the refractory bricks, forming a new low eutectic substance without bonding strength. This leads to the formation of low-melting polymers and low-melting substances on the surface of the refractory bricks. Driven by the movement and friction of the material, the surface will eventually fall off, resulting in the thinning of the refractory bricks.

Since the main components of silicon-alumina refractories are mullite and corundum, the main components are SiO₂ and Al₂O₃. The alkali metals contained in the hazardous waste can react with refractory bricks to generate nepheline-like substances and cause the volume expansion of refractory bricks. It may also cause the melting point to decrease, which in turn increases the corrosion effect on the refractory bricks, and accelerates the thinning rate of the refractory bricks, and shortens the service life.

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How to Improve the Performance of Refractory Bricks for Hazardous Waste Rotary Kiln

Pure magnesia refractories have very poor resistance to alkaline residues. However, when magnesia-alumina spinel is added to magnesia materials, it can well prevent the permeability of alkaline residues to refractory materials. And as the amount of magnesia-alumina spinel added increases, the penetration resistance will gradually become stronger, but the additional amount should not exceed 20%.

Sodium salts have a strong ability to corrode carbon-magnesia refractories, and it is possible to increase the effect of alkalis to a higher degree at lower temperatures.

After studying the reaction characteristics of alkali metals and refractory materials, the results show that changes in temperature, excess air coefficient, Cl content, and S content will all affect the migration of alkali metals. Therefore, it is recommended to choose composite components according to the actual situation when selecting molded refractories. The properties of refractory materials can resist the combined action of multiple corrosive factors.

Taking sodium carbonate as the research object, the corrosion mechanism of refractory materials is studied from the aspects of corrosion thermodynamics and kinetics. The results show that magnesia-containing refractories have better thermal stability than chrome-containing refractories.

Randomly take incinerator slag as a sample, and draw the following conclusions through some research and demonstration.

(1) Clay bricks, high alumina bricks, and chrome-containing high alumina bricks were used for erosion tests. The results show that the corrosion resistance of chrome-containing high alumina bricks is better than that of high alumina bricks and better than clay bricks. Considering that chrome is a toxic substance, high alumina bricks are selected as production bricks.
(2) Optimize the masonry method. Strictly control the key points of masonry to reduce corrosive infiltration to extend the service life of refractory bricks.
(3) Improve the quality of kiln-hanging leather by exploring the formula and method of kiln-hanging leather. Extend the kiln skin period, thereby increasing the protection of refractory bricks and reducing wear and erosion.
(4) Explore the best spray gun design by optimizing the liquid waste spray gun. In order to reduce the direct injection of liquid waste onto the surface of the refractory bricks, the corrosion and thinning of the refractory bricks will be caused.

RS Refractory Material Manufacturer — RS Refractory Bricks Manufacturer

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Rongsheng Refractory Manufacturer

Rongsheng is an experienced refractory material manufacturer. We also have rich experience in the production and sales of refractory materials for hazardous waste rotary kilns and cement rotary kilns. And every year, we can receive customer return orders. If you need to replace the refractory lining of your rotary kiln, or you need to build a new rotary kiln, please contact us. Our company’s refractory lining materials not only have the price advantage of the factory but also we provide high-quality customer service. Look forward to working with you.

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Jun 20 2020

How to Choose Refractory Lining for Blast Furnace?

How to choose refractory lining for blast furnace? In the design of refractory materials for blast furnaces, the different working conditions and erosion mechanisms of each part of the blast furnace should be fully considered, combined with the conditions of the original fuel, and the refractory materials should be selected in a targeted manner. The high-quality Refractory Lining for Blast Furnace, which can not only improve the service life of the blast furnace but also greatly save the production cost.

Construction Refractory Lining for Blast Furnace

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Therefore, according to the different working conditions of different parts of the blast furnace, the selection of refractory lining for blast furnace used in each part is as follows.

(1) Furnace bottom, hearth, taphole area, and tuyere belt.

The development of longevity technology in the hearth and hearth bottom has gone through a long process. The mainstream models of the entire hearth and hearth bottom structure are the “carbon + ceramic composite hearth and hearth bottom” structure and the “carbonaceous hearth + integrated hearth bottom” structure, these two technical systems.

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The heat-resistant castable is used below the furnace bottom water-cooling pipe centerline to the elevation of the heat-resistant foundation pier top. Carbon refractory ramming material is used between the centerline of the furnace bottom water-cooled pipe and the first layer of fully covered carbon brick. The first, second, and third layers are covered with semi-graphite carbon blocks, and the fourth layer is covered with microporous carbon bricks. There are also carbon bricks and ultra-microporous carbon bricks, the bottom of the furnace is made of two layers of ceramic pads, and the hearth is made of ceramic walls. The ceramic is beneficial to the heat preservation of the hearth slag and is conducive to saving the coke ratio and active hearth.

By adopting strong cooling measures in which the furnace bottom water cooling tube is buried under the furnace bottom brick, and the building method of the carbon furnace and ceramic. The goal of reducing erosion rate and longevity of blast furnace can be achieved.

The taphole area is built with carbon composite bricks. A composite brown corundum combined brick structure is adopted in the tuyere area. Its anti-slag iron corrosion and thermal shock resistance are good, the overall performance is good, and it has good protection for the tuyere-cooler casings. At the same time, it supports the refractory brick lining of the furnace belly.

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(2) The area of furnace belly, furnace waist, and furnace body.

A thin furnace lining structure with an integrated refractory brick wall is adopted, and the lining of cast iron cooling plate refractory brick is integrated with the cooling wall by cold setting. The production practice of the steel mill proves that this design structure can fully meet the normal service life of the blast furnace for 12-15 years.

The furnace belly, furnace waist, and lower part of the furnace body are inlaid with silicon carbide bricks combined with silicon nitride. The middle of the furnace body is made of fired microporous aluminum carbon brick. The middle and upper parts of the furnace body are lined with phosphoric acid-impregnated high-density clay bricks.

(3) Refractories for furnace throat

Furnace throat plays a role in protecting furnace lining and reasonable cloth. This area is mainly affected by direct impact and friction from blast furnace incoming materials. Because the temperature of this part is not high, about 400~500℃, the refractory materials used are mostly dense clay bricks, high alumina bricks, and sillimanite bricks. But the service life is still short, so it is also protected by wear-resistant and impact-resistant cast steel bricks.

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(4) Furnace top and riser.

Spraying materials with strong CO corrosion resistance and high thermal flexural strength.

(5) Between the cooling stave and the furnace shell.

The grout is pressed into the refractory mortar without water.

Rongsheng refractory brick manufacturer

Rongsheng is a refractory manufacturer with more than ten years of production and sales experience. Our refractory brick and refractory castable production lines are equipped with advanced production equipment. Moreover, our experienced technical engineers of refractory materials always pay attention to the development of refractory materials and customize refractory products for customers’ refractory linings. Our refractory products have been sold to more than 60 countries around the world, such as Malaysia, South Africa, India, Indonesia, Pakistan, Netherlands, Kuwait, Kenya, Russia, United States, etc. If your blast furnace needs refractory bricks or refractory castables. Please contact us with your details requirements, we will provide you with efficient refractory service.

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Tag Archives: refractory materials

Refractory Configuration and Optimization for a 5000t/d Clinker Line (1)

Refractory Lining Configuration for a 5,000 t/d Cement Clinker Production Line

(1) Preheater System

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(2) Tertiary Air Ducts

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Composition and Structure of Refractory Materials for Industrial Furnace Lining

Design of Industrial Furnace Lining Structure

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Inner Lining Structure of Industrial Furnace

Refractory Brick Masonry

Amorphous Refractory Lining

Refractory Ceramic Fiber Lining

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The Characteristics of Refractory Materials for Hazardous Waste Rotary Kilns

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Characteristics of Refractory Materials for Hazardous Waste Incineration Rotary Kiln

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Corrosion of Refractory Materials in Hazardous Waste Rotary Kiln

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How to Improve the Performance of Refractory Bricks for Hazardous Waste Rotary Kiln

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Rongsheng Refractory Manufacturer

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How to Choose Refractory Lining for Blast Furnace?

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Rongsheng refractory brick manufacturer

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