How to Install refractory lining

 Refractory lining play an important role in steelmaking. Learn how to use refractory lining and find out additional information about Refractory lining. This article describes in detail how to install Refractory lining and informs about other related knowledge about Refractory lining, read this article to have a detailed understanding of Refractory lining.

Installing the Refractory Lining. After consulting with the refractory technician, industrial refractory installation is conducted.

Curing the Refractory Lining. 

Refractory Installation Temperature Control. 

Water Removal of Refractory Installation. 

Drying Out Process.

A refractory lining usually comprises a safety or backup layer behind the working lining in contact with the furnace contents. The whole body is encased in a metal shell. The temperature gradients in the system and the properties of all materials must be considered.

Process of Refractory Lining Installation

1. INSTALLING THE REFRACTORY LINING

After consulting with the refractory factory, industrial refractory installation is conducted. 

This process is the mixing of a certain amount of water with a fixed amount of refractory castable.

If not, the incorrect amount of water can spoil the refractory lining. Among these are lower strength, longer time to set, and more water to remove during the dry out process.

Hence, the technician must use the right amount and type of water. Refer to the refractory material datasheet for the utmost accuracy.

2. CURING THE REFRACTORY LINING

The castable refractory curing procedure is the process where the water reacts with the refractory cement. It is completed when the refractory material has hardened to its final form.

However, it is an intricate process. This is because the temperature of surroundings and castable can impact curing success.

Thus, curing needs a precise temperature range for it to work. Lower temperatures can weaken the curing. This will lead to lower permeability and longer curing time.

Comparably, higher temperatures will set the refractory product too quickly. Hence, it will affect the densification, making the refractory lining unfit for application.

3. REFRACTORY INSTALLATION TEMPERATURE CONTROL

Temperature is a major part when installing refractory. So store all refractory materials and equipment under a controlled setting.

If they are cold, you will lose precious time waiting for them to reach the desired temperature. Thus, refractory contractors put heaters surrounding the curing process depending on the ambiance.

Additionally, uncontrolled storage and mixing temperatures will disrupt further steps to refractory installation methods. Hence, causing severe spalling to the refractory lining

4. WATER REMOVAL OF REFRACTORY INSTALLATION

After installing and setting the refractory monolithic, the next step is water removal. To do this, apply heat to remove both physical water and chemical water.

Then, the water will evaporate at certain temperatures. However, the steam will cause volume expansion which can increase the internal pressure.

By applying the correct methods, the refractory lining is stronger with no risk of spalls.

5. DRYING OUT PROCESS

Lastly, conduct the drying out process for the refractory castable lining.

The dry-out process requires expertise from the right refractory engineering factory. If done improperly, the refractory lining will crack and weaken quickly. Also, the steam explosion might happen, risking the workers and the refractory project.

Therefore, discuss with your refractory technician for a dry-out plan of your plant.

Changxing Refractory Material

Types of Refractory Lining Materials

Refractories can be classified based on various different parameters in multiple ways as listed below:

Based on Chemical composition:

Acidic refractories (Silica refractories, Zirconia refractories, Aluminosilicate refractories);

Basic refractories (Magnesite refractories, Dolomite refractories, Magnesia-chrome refractories);

Neutral refractories (Carbon graphite refractories, Alumina refractories, Chromite refractories)

Method of manufacture: Dry press process, Hand molded, Fused cast, Formed, Unformed.

Fusion temperature: Normal refractories, High refractories, Super refractories.

Refractoriness: Super duty, High duty, Intermediate duty, Low duty.

Thermal conductivity:

Heat-resistant (temperatures≤ 1100 °C),

Refractory (temperatures≤ 1400 °C),

High refractory (temperatures≤ 1700 °C),

Ultra-high refractory (temperatures ≤ 2000 °C).

Purpose of Refractory Lining

Refractory lining is widely used in very high-temperature services.

Serve as a thermal barrier between the pipe/equipment wall and hot medium.

Withstand physical stresses.

Protect against corrosion and erosion.

Provide thermal insulation

Refractory Lining Materials 

The common materials that are used as refractory lining materials are:

Alumina or Aluminum oxide (High Alumina bricks)

Silicon oxide

Magnesium oxide

Calcium oxide

Fire clays (Clay bricks)

Zirconia

Silicon carbide

Tungsten carbide

Boron nitride

Hafnium carbide

Molybdenum disilicide

Tantalum hafnium carbide

Corundum bricks

Plastic refractory

Refractory lining material consists of refractory aggregate, admixture, powder, binder, water, or other liquid, made of amorphous refractory products or fixed refractory products.

Induction Furnace Refractory Products

The refractory tamping process for induction furnaces is a critical step that must be performed carefully to ensure the longevity and efficiency of the furnace. Here is a step-by-step guide for tamping induction furnace refractory wall material:

Filling the floor with refractory: First step is to fill refractory carefully on the furnace floor and then leveling it. Pay attention to grounding cables.

Using bottom (floor) ramming machine: Place bottom rammer into the furnace and then start vibration with the desired duration depending on furnace size. Check leveling then remove machine after bottom refractory is tight enough.

Placing the former for wall ramming: Place the steel former into the middle of furnace. Use some tools to fix it into the position and make sure it won't move while the vibration.

Filling the refractory material into the wall: Fill refractory material space between former and furnace wall. De-air with fork tool into the layers while filling completely.

Ramming the wall refractory material: Wall rammer are placed into the former, and a level close to the bottom floor. Vibration starts and wall ramming machine starts rotating while making hits into the steel former. These hits create vibration and impact in granular refractory lining material. Wall ramming machine raised up step by step until to the surface while working and hitting.

Curing: Once the refractory material has been rammed, it must be allowed to cure. The curing time can vary depending on the specific refractory material used and furnace size.

By following these steps carefully, it is possible to create a durable and long-lasting refractory lining for an induction furnace. It is important to use high-quality refractory materials and equipment to ensure optimal results.

Article Source: How to Install refractory lining
Company name: Henan Changxing Refractory Materials Co.,Ltd
More refractory products:https://www.cxrefractories.com/en-all-refractory-products
Email:info@cxrefractories.com
Website:https://www.cxrefractories.com

How to choose right refractory castable for your needs

 

1.Refractory castable based on Application

Generally, the refractory material is engineered to perfection. But, it might not suit your refractory lining. Focus on the type of application of your refractory insulation. Choose suitable refractory products.

2. Choose Common Refractory Materials

Basically, everyone wants fast and cheap options, no matter the industry.

However, choosing cheap refractories ceramics will cost more in the future. So, consider buying the tried and tested refractory material regardless of price.Because refractory contractors know they are best for boiler refractory and furnaces.

3. Research Refractory Lining Trends

Although there is new refractory insulation technology, discuss with your refractory contractor first.This is because trends may seem too good to be true. Avoid asking for new types of furnace bricks for your refractory contractor to use.The engineering contractor will suggest a material that suits your refractory insulation.

4. Choose the Right Refractory Contractor

Basically, everyone thinks they are the best. But, in the end, the most experienced engineer will make the correct decision. Therefore, choose a refractoryfactory that fits your criteria. Then, they will provide refractory products and services that suit your refractory lining.

Different Refractory Castable

Things To Remember When Using Castable

1. Castables must always be stored in a cool and dry area.

2. One must ensure that the mixers and tools are free from old castable or any other material that can contaminate the product. Such contamination could affect the strength of the castable mix.

3. Only drinking suitable water should be used to mix castable. The temperature of the mix should be optimal as well.

4. Be careful while mixing castable, like castable refractory cement. Too much mixing generates heat and speeds up the setting time.

5. The forms should be covered with oil or grease to prevent moisture loss.

6. After placing the mix, the castable needs to be cured for 18 to 24 hours straight. Cover it with polyethylene sheets and spray it with cold water periodically. It will maintain the moisture of the mix and promote uniform curing at the applied area.

   

Silica Ramming Mass

Advantages Of Castable Refractories

Saves Time

Ease in usage

Significantly Better Structure Performance

Choosing refractory castable for the insulation process is one of the most thoughtful decisions. Their advantages and wide application seal the deal.  But what is even more important is finding a reliable refractory material supplier.  Welcome to contact us anytime.

Article Source: How to choose right refractory castable for your needs
Company name: Henan Changxing Refractory Materials Co.,Ltd
More refractory products:https://www.cxrefractories.com/en-all-refractory-products
Email:info@cxrefractories.com
Website:https://www.cxrefractories.com

How to improve service life of ladle purge plug

 Ladle purge plug or porous plug is a critical component in ladle bottom purging system. Apart from the purge plug life its reliability, gas flow rate quality of steel produced etc are evolving as the most important parameters to judge the purge plug quality.

Methods to improve service life of ladle purge plug

The wear of the purging plugs mainly consist of erosion due to intensive liquid steel stirring, corrosion by aggressive iron-oxide rich slag at high temperature and, as well as the spalling of layers from the hot face, which is owing to horizontal cracking.In order to prolong the service life of purging plugs, many efforts have been made by adjusting the chemical components so as to improve the material properties.

1.The results showed that higher refractoriness and better iron-oxide-rich slag corrosion resistance could be achieved in the non-cement systems. 

2. Systematically investigated the effect of cement contents on the mechanical properties and found that the phase compositions and microstructure can be optimized through adjusting the cement content in corundum castables. 

3. Furthermore, Prepared three kinds of castables, of which physical properties were characterized along with their microstructures at both room temperature and high temperature to increase cold and hot mechanical strengths. It was concluded that the calcium hexaluminate phase in the matrix of the corundum-based low-cement castable enhances the cold and hot mechanical strengths.

As a part of ladle lining, the geometries of the purging plug may also influence their temperature distribution, stress responses, and service life. It was found that two optimal lining concepts were proposed to decrease heat loss through the steel shell and thermomechanical load at the hot face of the working lining.  

Ladle refining furnaces are widely employed in the modern steel-making process for decarburization, desulfurization, inclusion removal and homogeneous temperature and composition. As the crucial part of the ladle, purging plugs experience an intermittent thermal shock when the liquid steel is poured into and out of the ladle in cycles during the refining process. Moreover, an intense extra heat exchange occurs within the purging plug when the argon is continuously blown into the liquid steel through the slits assembled in the purging plug. Due to these severe service conditions, the working time of the purging plug, is less than that of the refractory lining of the ladle. Consequently, downtime is needed to repair or replace the purging plug, which leads to more energy consumption and lower production efficiency. Therefore, the service life of the purging plug has long been recognized as an important issue in improving steel-making production efficiency.

What are the causes of damage to a ladle purging plug?

Due to vigorous lancing (oxygen )

Due to Back Pressure when plug chowking

If Purging Plug well Block not patching regular

Due to boundary side oxygen lancing with high pressure.

The main reason of damage to refractory materials, including chemical erosion, mechanical abrasion and thermal stress. Thermal stress which is caused by damage to the refractory cracking the direct cause of damage.

The purging plug is an indispensable refining component; Its slit structure and distribution are important factors that influence refining efficiency.

To achieve homogenous temperature and composition of steel by fostering of slag metal refining reaction Argon gas is purged through bottom purging blocks into the steel bath. Purging is the most important activitiy in secondary steel refining process. For smooth running of the process with less downtime, plug performance need to align with operation without failure. Ladle Purging brick are widely used in the secondary refining process, and its service life determines the downtime and usage efficiency of the whole ladle.

Ladle Purge Plug

More details about ladle purge plug

What is purging in ladle?

To achieve homogenous temperature and composition of steel by fostering of slag metal refining reaction Argon gas is purged through bottom purging blocks into the steel bath. Purging is the most important activitiy in secondary steel refining process.

What is purging in steel plant?

Purging is an inerting method commonly used in safety-critical process chambers such as reactors to eliminate oxygen and moisture when operations are started up or shut down.

What does purging mean in steel ladle?

Dual gas purging is often done in a ladle to accelerate the refining operations in steel industries. The purged gas, mainly argon imparts momentum to the molten metal and establishes a turbulent recirculating flow in the melt, which generates shear stresses on the ladle walls.

What is ladle purging?

The purpose of ladle purging plug used by steelmaking factories is to remove harmful gases and impurities, adjust the composition, so as to complete the basic tasks of oxygen supply, slagging, stirring, heating and other steelmaking.

Article Source: How to improve service life of ladle purge plug
Company name: Henan Changxing Refractory Materials Co.,Ltd
More refractory products:https://www.cxrefractories.com/en-all-refractory-products
Email:info@cxrefractories.com
Website:https://www.cxrefractories.com

How to prevent the tundish nozzle from clogging

 Tundish nozzle plays a very important role in ladle steel making.It is very important to learn the measures to prevent the clogging of the nozzle of the tundish. There are some measures to stop clamping at tundish nozzle.

Measures to stop clamping at tundish nozzles

(1) Ensure that there is no deformation in the sliding mechanism of the continuous casting sizing nozzle, there is no foreign matter on the sliding stroke of the sizing nozzle, and the gap between the sizing nozzles is less than or equal to 0.3mm.

(2) The size of the zirconium sizing nozzle is reasonably designed, there is no damage and cracks before use, and the board surface is flat without unevenness.

(3) The production rhythm is stable, the quality of molten steel is qualified, and there is no phenomenon of high and low temperature and molten steel interception.

(4) The personnel for replacing the sizing nozzle are skilled, and there should be no accidental burning or diameter expansion caused by human factors.

The disorder of casting process because of nozzle clogging is a long-standing issue ever since the continuous casting process has been introduced. Nozzle clogging is the build-up of solid or semi-solid material on a refractory surface which can become problematic during steel pouring, as it can affect the stream dynamics, reduce the pouring rate, and cause large agglomerated particles to be intermittently released into the liquid steel stream in severe cases. Because of the nozzle clogging, the casting speed is frequently decreased, and even an entire cast is to be abandoned.  Further, nozzle clogging can give rise to both quality and productivity problems.

During the continuous casting of liquid steel, steel flows from the tundish to the mould through a submerged entry nozzle, (SEN) as shown. This protects the liquid steel from reoxidizing in contact with the atmosphere. The flow rate is controlled with a gate or stopper rod to maintain optimum casting conditions. If the nozzle clogs and the flow control cannot make up for the reduced flux, the nozzle has to be replaced which means the production is interrupted. The clog build-up can also result in decreased steel quality as oxide particles can loosen from it, giving rise to rather large inclusions.

Tundish nozzle clogging problems take several different forms, and can occur anywhere inside the nozzle, including the upper well, bore, and ports. They are classified into four different types according to their formation mechanism namely

 (i) the transport of oxides which are present in the steel to the nozzle wall,

 (ii) air aspiration into the nozzle,

 (iii) chemical reaction between the nozzle refractory, and the steel, and (iv) steel solidified in the nozzle. In practice, a given nozzle clog is frequently a combination of two or more of these types, and its exact cause(s) can be difficult to identify.

Problems caused by clogged tundish nozzles:

Clogging of the tundish nozzle is a major castability problem in continuous casting of steel for several reasons. Firstly, clogging increases the frequency of operation disruptions to change nozzles or tundishes or even to stop casting. These extra transitions increase operating cost, decrease productivity, and lower quality. Secondly, clogging can lead directly to a variety of quality problems. Clogs change the nozzle flow pattern and jet characteristics exiting the ports, which can disrupt flow in the mold, leading to surface defects in the steel product and even breakouts. Dislodged clogs also disturb the flow and either become trapped in the steel or change the flux composition, leading to defects in either case. Quality problems also arise from the mold level transients which occur as the flow control device compensates for the clogging.

FAQ:

What is a tundish nozzle?

Tundish Nozzles are an integral part of Continuous Steel Casting process. These products are instrumental in controlling the flow of Molten Steel from Tundish to Continuous Casting.

What is the HS code for tundish nozzle?

69032090

What is the function of a nozzle?

The primary function of a nozzle is to control flow rate and convert the spray liquid into droplets (via atomisation) that are of a suitable size for depositing on the intended target.

What are the uses of tundish?

What does a tundish do? A tundish is installed to prevent cross-contamination between an overflow pipe and a drain pipe. Unsanitary water from the drain pipe could theoretically enter the system if a tundish is not installed to block this.

The number of melting sequences is important in choosing a Tundish nozzle. Different nozzles for single use Melting or multiple melts are produced and used. It seems necessary to use more resistant material to achieve higher sequences. Welcome contact us to choose the right nozzle at the lowest cost.

How to make magnesia brick

 

Magnesia Brick Manufacturing Process: 

The manufacturing process of magnesia brick includes the following steps:

1. Break and smash: 

Crushing is the process of processing large pieces of material into ideal particle size materials. 

2. Ingredients (weighing): 

The raw materials are prepared in a predetermined proportion and mixed in a strong sand mixer. The order of feeding is magnesia aggregate – carbon fiber – binder – carbon raw material. 

3. Mixing: 

Mix thoroughly to get perfect coating. Add mixture made in step (B) and remix the batch intensively. Now add powder Resin (item 9), then Hexamine (item 10) and mix once again. 

4. Molding: 

Use a molding machine to make the mixture into bricks.

5. Drying:

Use a drying oven to dry the bricks for several hours.

6. Firing: 

Fire the bricks in a kiln at temperatures of 1550 to 1600 degrees Celsius. 

7.Finishing: 

The final step is to grind and polish the bricks to get the desired shape and size.

Types of magnesia brick:

Magnesia bricks can be divided into two categories: sintered magnesia bricks (also known as fired magnesia bricks) and chemically combined magnesia bricks (also known as unburned magnesia bricks). Magnesia bricks with high purity and firing temperature are called direct-bonded magnesia bricks due to the direct contact of periclase grains; Bricks made of fused magnesia as raw materials are called fused re-bonded magnesia bricks.

Uses of Magnesia Bricks:

Magnesia bricks are used in steelmaking furnaces, electric furnace bottom and wall, and high temperature tunnel kiln. Magnesia bricks are also used as heat storage room lattice bricks in glass kilns.

Magnesia brick is used for permanent layers in steel making converters, AOD furnaces, and more. Magnesia brick is also used to line steel ladles and Basic Oxygen Furnaces (BOFs). Magnesia bricks can be used in a variety of applications, depending on the type of brick being used. Common uses include furnaces, ladles, secondary refining vessels, and cement and glass making kilns.

Magnesia Brick for sale

The most important steps need to be considered to avoid or reduce the possibility of magnesia bricks hydration are:

1). Magnesia bricks must be transported in a container to protect the material against moisture.

2). Magnesia bricks should be stored inside storage rooms where it is dry, free of frost, ventilated, and with a temperature between 10°C and 30°C. Note that magnesia bricks storage underneath a tarpaulin cover outside is not sufficient.

3). Bricks may not be stored for more than four weeks prior to installation and preheating.

4). Lining should be protected against moisture during installation and preheating.

Article Source:How to make magnesia brick
Company name: Henan Changxing Refractory Materials Co.,Ltd
More refractory products:https://www.cxrefractories.com/en-all-refractory-products
Email:info@cxrefractories.com
Website:https://www.cxrefractories.com

How to reduce ladle nozzle clogging during continuous casting

 The article explains how to prevent ladle nozzle blockage, what causes ladle spout blockage. Learn how to prevent ladle nozzle blockage and the factors that lead to ladle nozzle blockage.

How to reduce ladle nozzle clogging, as the following:

Preventing ladle nozzle clogging is not successfully completed by one simple action but rather many actions working together: inclusion count reduction, inclusion modification by the use of calcium, protecting from re-oxidation of the steel, proper tundish geometry, and proper tundish and nozzle refractories. While the concept of making only liquid inclusions appears simple in application, it can be rather difficult to maintain these liquid inclusions throughout the entire casting process.

Nozzle clogging during steel pouring in the continuous casting process is a long-standing problem for Al-killed steels. During casting the flow rate of liquid steel through the nozzle is reduced due to the nozzle clogging, which leads to serious operational problems. Even though the ladle slide gate is fully open, the molten steel flow rate can hardly meet the demand of the tundish, causing the level in the tundish to drop. To continue the casting sequence the casting speed must be reduced. In some cases casting is terminated if clogging takes place at early stage of ladle opening and the ladle returns with the remaining steel poured in the EAF/ other ladles for reprocessing or lost as ladle loss. Ladle nozzle clogging reduces productivity, decreases process yield and impacts the steel quality. 

Ladle Nozzle Clogging can be divided into three classes and is grouped according to their sources:

Class 1: Oxide formation :

Category -1.1 by air aspiration, 1.2 by reaction between nozzle refractory and steel.

Class 2: Transportation of oxides to the nozzle wall :

Category – 2.1 deoxidation products, 2.2 reoxidation products, 2.3 exogenous inclusions, 2.4 products of inclusion modification.

Class 3: low temperature chilling of steel

A way to solve ladle nozzle clogging.The concluded that:

The bigger diameter of a nozzle or less nozzle clogging could effectively generate an enough flow rate for a CC process and maintain the target casting speed. We can predict if nozzle clogging is happening by comparing the actual value and the theoretical one of the percentage of a slide gate opened

The main inclusions which caused the nozzle clogging during a CC process of the silicon steel were Al2O3 and its composite inclusions.

Ca-treatment can be a method that transform inclusions into C12A7 by adding Si-Ca wires and prevent nozzle clogging of the silicon steel theoretically. And the amount of Si-Ca wires for Ca-treatment of the silicon steel, with different dissolved Al and total O can be calculated. Ca-treatment can prevent the nozzles from clogging during a CC process of the silicon steel.

Ladle Nozzle Manufacturer

Ladle nozzle clogging during a continuous casting process

To figure out the reason causing ladle nozzle clogging during a continuous casting process for the silicon steel and get away to solve it, the theoretical calculation of flow rates during casting, inclusions around the ladle slide gate where ladle nozzle clogging happened, and Ca-treatment on refining units for producing the silicon steel. 

The bigger diameter of a nozzle or less nozzle clogging can guarantee an enough flow rate for reaching the target casting speed. Ladle nozzle clogging can be predicted by analyzing the percentage of a slide gate being opened. Al2O3 and its composite inclusions were the main ones which cause the nozzle clogging during the CC process of the silicon steel. Ca-treatment could transform those high melting point inclusions into C12A7 by adding Si-Ca wires and prevent the ladle nozzle clogging of the silicon steel.

Due to nozzle clogging, a casting speed often decreased, and even an entire cast would be canceled in severe cases. The transformation of inclusions, electroslag remelting process (ESR for short), and ceramic filters were effective methods to reduce the clogging. And calcium-treatment for transforming inclusions was thought as a lower cost and a simpler process than the others, and thus there were many studies on it for solving the clogging of submerged entry nozzles. 

Some steel with high silicon, such as welding steel, calcium should be not be added into the steel, because it can increase the welding cracks of the steel. That meant that not all steel can use calcium-treatment for solving the clogging, and there has no been a research on ladle nozzle clogging of silicon steel. But there has been being ladle nozzle clogging during CC of silicon steel, which is deoxygenated by using Al. Moreover, silicon steel has unique properties and its processes are more complicated compared to other steel. Therefore, it is necessary to study what causes ladle nozzle clogging for casting silicon steel, figure out a effective method to solve the problem, and confirm that the method would not obviously affect the properties of silicon steel. The theoretical calculation for flow rates that could affect nozzle clogging, analyzed the inclusions causing the ladle nozzle clogging, validated the effects of Ca-treatment on solving ladle nozzle clogging of the silicon steel both theoretically and practically, without a decrease of the magnetic properties.