Tabular Alumina for High Purity Corundum Brick

High purity corundum brick with Al2O3 content above 99% is studied based on tabular alumina and white fused alumina (WFA) as single aggregate and the combination of both. In comparison with Tabular alumina, WFA aggregate has relatively higher SiO2 content of above 0.10% and shows fluctuation on soda content. WFA also has a high open porosity of 8.8%, which very often exists in the form of single large pore or in the form of agglomeration of pores rather than the small closed and evenly distributed pores in tabular alumina. Refractory brick china with different ratio of tabular alumina and WFA have been tested for firing shrinkage, bulk density and apparent porosity, cold and hot strength, thermal shock resistance, and abrasion resistance. Also slag tests with a coal gasifier slag and an oil cracking slag have been conducted. The results from this evaluation conclude that high alumina brick outperforms WFA bricks and importantly gives more balanced performance.

Introduction
High purity corundum brick is widely used as refractory lining for oil cracking unit, coal gasifier, carbon black furnaces, black liquor gasification and other industrial furnaces. This is attributable to the outstanding performance of corundum brickon chemical corrosion resistance, mechanical abrasion resistance and thermomechanical properties like high temperature strength, refractoriness under load and creep resistance, even in environments with corrosive gas or liquid and with high pressure.
Synthetic alumina based aggregates like white fused alumina and tabular alumina are the two main aggregates available for high purity corundum brick. They are selected due to low impurity content (e.g. SiO2), high bulk density and thermomechanical properties, which enables corundum bricks that meet the requirements on thermal, chemical and structural attacks [1] which gasifiers and other furnaces apply in operation.

The different processes for WFA and tabular alumina production (fusion vs. sinter) certainly create differences between the aggregate, which also have an impact on the properties and performance of the corundum brick. Tabular alumina is well received and extensively used in the refractories for steelmaking such as slide gate plate, Al2O3-MgOC brick, castables and pre-cast shapes.

However, for a long period of time, WFA is very commonly used as the aggregate for high purity corundum brick to non-steel applications like gasifier and other industrial furnaces. It is often claimed that WFA aggregate has higher bulk density which consequently increases the density of fire brick China and the corrosion resistance which could enhance the overall performance. However these perceptions should be investigated by an extensive evaluation. This work is designed to evaluate in a comprehensive way the differences on performance of tabular alumina and white fused alumina in respect to aggregate itself and brick properties in order to understand these differences and provide appropriate application guideline for high purity corundum brick.

1. Refractory raw material Almatis global tabular alumina product T60/64 and a common commercial Chinese WFA grade are selected as the aggregate and fine. In the matrix, Almatis’ calcined alumina CT800FG is also used. Sulphite pulp liquor is used as temporary binder for corundum brick making.

2. China refractory brick formulation Five recipes are used in this evaluation. As per the tabular alumina content in aggregate, the formula is named as T100, T75, T50, T25 and T0 and the numbers stand for tabular alumina content in respective brick. Table 1 gives the details with bold highlighted for tabular alumina.

Article Source: refractory fire brick
Company name: Henan Xinmi Changxing Refractory Materials Co.,Ltd
Email: sales1@chinafirebrick.com
Website:http://www.chinafirebrick.com/

The advantage and disadvantage of graphite electrode

Ultra-high power graphite electrode:
Graphite electrodes is mainly made of petroleum coke and needle coke as refractory raw materials, and coal tar pitch as a binder, which is prepared by calcining, compounding, kneading, pressing, calcining, graphitizing and machining and is released in an electric arc furnace Electrical energy on the charge heating and melting of the conductor.
Ultra-high-power graphite electrode are graphite electrodes that allow current densities greater than 25 A / cm2 and are mainly used in ultra-high-power steelmaking electric arc furnaces.
HP Graphite electrode advantages:
(1) Processing speed is faster: Under normal circumstances, graphite machining speed can be 2 to 5 times faster than copper; and discharge processing speed is 2 to 3 times faster than copper;
(2) The material is more difficult to deform: obvious advantages in the thin-walled electrode processing.
(3) lighter weight: the density of graphite is only 1/5 of copper, large electrode for electrical discharge machining, can effectively reduce the machine tool (EDM) burden; more suitable for large mold applications.
According to the use of different power and current, using different refractory raw materials and production technology, can be divided into ordinary power graphite electrodes, high power graphite electrodes, ultra-high power graphite electrodes. Graphite electrode has good electrical properties and chemical stability, high mechanical strength at high temperature, low impurity content, good vibration resistance, is a good conductor of heat and electricity.
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Graphite electrodes are widely used in steel-making electric arc furnaces, refining furnaces, ferroalloy production, industrial silicon, yellow phosphorus, corundum and other submerged arc furnaces and other arc furnaces that produce high temperatures.
HP Graphite electrode has good electrical properties and chemical stability, high mechanical strength at high temperatures, less impurities, good vibration resistance. It is a good conductor of heat and electricity.
Article Source: HP Graphite Electrode
Company name: Henan Xinmi Changxing Refractory Materials Co.,Ltd
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The features and application of graphite electrode

Graphite electrodes find application in manufacture of Steel and other non-ferrous metals through the Electric Arc Furnace and the Laddle Furnace routes. It is used as a consumable for conducting high current at low voltage which is necessary for melting and / or alloying processes.

Graphite is the unique material for Electrodes as it optimally fulfils the requirements on the following criteria :
Electric and Thermal Conductivity
Mechanical Strength
Thermal Shock Resistance
Machinability
Thermal Expansion

We are instrumental in manufacturing for our clients a commendable array of HP Graphite Electrode that are demanded for their ease of use, long time service and options for wide ranging usages. Offered range also incorporates Ultra High Power Graphite Electrodes, High Power Graphite Electrodes and Regular Power Graphite Electrodes. These offered Electrodes are prepared by using LWG Furnaces, advanced machinery and latest techniques. Backed by its excellent attributes, this offered range is extensively applauded by our patrons. Addition to this, we ensure customized product for the gratification of esteemed clients.

High power graphite electrodes refer to graphite electrodes that allow the use of current densities below 17 A / cm2. They are mainly used in electric arc furnaces, refining, ferroalloy and submerged arc furnaces.

HP Graphite electrode has advantages of high mechanical strength, low impurity content and good vibration resistance. We are amongst the leading names in the industry, offering technically advanced range of High Power Graphite Electrodes that are performance oriented and are functionally advanced in nature. They have high heating capacity and reduces the electrode consumption to the great extend. High power graphite electrodes reduces the melting cost and are offered at most affordable rates.

Article Source: HP Graphite Electrode
Company name: Henan Xinmi Changxing Refractory Materials Co.,Ltd
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Common castable for reheating furnace

1.Self leveling castable. Self leveling castable is applicable to the furnace parts which are more complex and can not be vibrated by workers.
2.Low cement castable. The low cement castable is suitable for the high temperature zone and moderate temperature zone of the heating furnace, and the service temperature is between 1400~1500 degrees centigrade.
3.Phosphate castable. Phosphate castable is suitable for heating furnace bottom and the zone where it rub with other refractory materials and erosion zone by hot wind. The service temperature is between 1000~1600 degrees.
4.Mullite castable. The mullite castable is charactorized with high thermal shock resistance, erosion resistance, good volume stability and high application temperature. So it is usually used in the key parts of the furnace wall, furnace top and depressed beam, or used to make the burner brick.
5.Light weight castable. The lightweight castable is used for the heat insulation layer of the furnace wall, furnace top, flue and other parts. High strength lightweight castable can also be used as the lining of exhaust systems and hot air pipes.
Article Source: Light weight castable
Company name: Henan Xinmi Changxing Refractory Materials Co.,Ltd
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The advantages of graphite electrode in chinafirebrick

Graphite electrode is an indispensable material used in the electric arc furnace steel making, for its excellent electrical conductivity and remarkable anti-thermal shock capability. We supply HP graphite electrode for the iron and steel sector. We specialize in providing graphite electrodes of 18 inch diameter and smaller, but larger diameters up to 28" are also available. Carbon electrode sizing ranges from 36" to 55" diameter. Our product line includes:

Advantages:
High temperature strength
Good thermal and electrical conductivity
Low thermal expansion
Appropriate machinability
These features make graphite electrode the most suitable material to melt scraps, DRI, etc.

We supply graphite electrodes for the iron and steel sector. Our main refractory product include:
Graphite and carbon sidewall blocks for aluminum smelting
Graphite electrodes for the steel and iron industry
UHP Graphite Electrodes
HP Graphite Electrode
General Power Graphite Electrode
We’re among the HP graphite electrode suppliers in the nation and can provide you with the raw materials you need at prices you can afford. We offer excellent customer service whether you order graphite electrodes and refractory fire brick.
Article Source: HP Graphite Electrode
Company name: Henan Xinmi Changxing Refractory Materials Co.,Ltd
Email: sales1@chinafirebrick.com
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The details of HP Graphite Electrode

High power graphite electrodes refer to the graphite electrode that allows the use of a current density of 18 ~ 25A / cm2.
Graphite electrode has good electrical properties and chemical stability. What’s more, graphite electrode has advantages of high mechanical strength, low impurity content and good vibration resistance. Graphite electrodes are good conductors of heat and electricity. Graphite electrode is widely used in steelmaking electric furnace, refining furnaces, production of ferroalloy, industrial silicon, yellow phosphorus, corundum , submerged arc furnaces and other smelting furnaces that produce high temperatures by electric arc.
According to the different of service power and electricity , using different raw materials and production technology, graphite electrodes can be divided into ordinary power (RP) graphite electrodes, HP graphite electrodes, ultra-high power (UHP) graphite electrodes.?

Application:

High power graphite electrode is mainly used in high-power electric furnace and ladle furnace.
Changxing refractory provides refractory products, calcium silicate products, castable & mortar,?china refractory brick, ceramic fiber felt, ladle & tundish nozzle, ceramic fiber with high quality for you. Such as high alumina refractory bricks, magnesia carbon brick, clay refractory bricks and other refractory products.
Article Source:HP Graphite Electrode
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The working mode of moulding powder

Moulding powder forms ”three layers”?in the crystallizer, powder layer, sintered layer and slag layer. This working mode is the key to play the role of moulding powder.

The casting powder (1100~1200℃ melting point) on the surface of the molten steel (1500℃), heated by the molten steel and forms slag layer with 10-15mm thickness on the surface of molten steel. With the heat transfer slowed down, the moulding powder above slag layer sintered, forms sintered layer (900-600℃). And the casting powder above the sintered layer will gets fewer heat transfer, less than 500℃, so this is the powder layer. And the moulding powder covers in the molten steel surface evenly, to prevent cooling and secondary oxidation of molten steel.

During casting, the slag film between crystallizer and solidified slab shell could reduce the casting resistance and improve the heat transfer of crystallizer. As casting going , the slag layer is consumed constantly, then sintered layer becomes slag layer, powder layer becomes sintered layer, and adds more moulding powder into the crystallizer, makes the moulding powder keeps “three layers“.

Article Source: Moulding powder
Company name: Henan Xinmi Changxing Refractory Materials Co.,Ltd
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