What are the difference between tundish nozzles and ladle nozzles in steel making

 This article explains the difference between ladle nozzle and tundish nozzle. Learn about the difference between ladle furnace andtundish furnace. Welcome to know more about refractory nozzle and other kinds of refractory products.

The different between tundish nozzles and ladle nozzles

Tundish nozzle and ladle nozzle are important components in the process of steelmaking, but they serve different purposes.  Tundish is used in the continuous casting process to distribute molten steel into the mold, while the ladle is used for transporting and pouring molten steel from the furnace to the tundish.

Refractory nozzles including a so-called long nozzle, an upper nozzle, a lower nozzle, and an immersion nozzle made from high-alumina refractory material, graphite powder, silica powder and other minor constitutents wherein a major part of the high-alumina refractory material.

This article relates to nozzles used around the ladle and the tundish in a steel manufacturing plant and made from specially processed refractories, and more particularly, it relates to those used in so-called continuous casting.

Tundish Nozzle Composition

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. Long casting sequence time. Controlled casting speed. 

Tundish Nozzles usually comprise a zirconia inner nozzle (often referred to as a “zirconia insert”) with a lower grade outer body such as Alumina, Zircon or Bauxite.

Ladle Nozzle Composition

Ladle-nozzle – a type of refractory products used in the process of non-stop casting of steel. They are part of the components of refractories to a steel casting slide gate. They are an integral replaceable part of the nest block.

Ladle nozzle is composed of upper and lower sliding plates and 4 refractory bricks for the upper and lower nozzles. The pouring of each ladle of molten steel must pass through the upper and lower sliding plates and the upper and lower nozzles, so they are very strict.

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. These are highly suitable for open casting.

Tundish Nozzle & Ladle Nozzle

What is the difference between tundish and ladle?

(1) The tundish nozzle is smaller than the ladle nozzle and is easy to be blocked by cooling. 

(2) The height of molten steel in the tundish is used to adjust and control the flow of molten steel in the tundish into the mold.

(3) The tundish allows a reservoir of metal to feed the casting machine while ladles are switched, thus acting as a buffer of hot metal, as well as smoothing out flow, regulating metal feed to the moulds and cleaning the metal.

What is Ladle furnace?

In steel: The ladle. An open-topped cylindrical container made of heavy steel plates and lined with refractory, the ladle is used for holding and transporting liquid steel.

The main purpose of the Ladle is to raise steel temperature and to control the chemical composition between tapping and casting, removing and/or modifying inclusions and acting as a buffer in melt shop logistics.

In the process of steelmaking, once the steel is made in the basic oxygen furnace, arc furnace or induction furnace, it is transferred into the ladle for further refining, chemistry adjustment, inclusion modifications, etc.All these treatments are carried out in the ladle. Additional heat is required to carry out these operations. Hence the ladle is provided with a heat source which heats the liquid metal and compensates thermal losses. Thus the furnace in which the quality of liquid steel is improved by refining and heating is called a ladle refining furnace (LRF). Our offer consists of a wide range of safe and reliable refractories ranging from slide gate to nozzle to nozzle changers and purging plug systems.

What is Tundish Furnace?

The tundish is a container of large dimensions that receives the steel from the ladle prior to its introduction into the continuous casting machine.

Tundish are highly responsible facilities within the casting process of molten steel, because they are subjected to high temperatures continuously and failure of them involves not only the production sequence, but also the safety of the plant.

The tundish is made from extremely durable materials which are capable of coping with the high heat of molten metals. The equipment is usually lined with a material with low conductivity, and may be fitted with a nozzle to control the flow of molten metal. In other designs, the pour is controlled by hand or by machine. Controlling the pour is important to avoid casting a piece with flaws such as cracks and bubbles, and to accommodate the needs of different metals.

More details about Ladle Nozzle & Tundish Nozzle

Which is the connector pipe between tundish and steel ladle?

In steel making, the shroud tube creates a connection between the ladle and tundish of the continuous casting plant allowing molten metal to flow between the two.

What is nozzle and diffuser?

A nozzle is a device which accelerates fluid. During this process, velocity of fluid increases with decreasing pressure. A diffuser is a device which slows down fluid. That means velocity of fluid decreases with increasing pressure.

What are the different types of tundish nozzles?

Different kind of tundish nozzles include, Alumina, Alumina Carbon, Zirconia Alumina Nozzles, which are manufactured for single to multiple casting application.

What is a tundish nozzle used for?

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. These are highly suitable for open casting.

What is a ladle nozzle used for?

Ladle-nozzle – a type of refractory products used in the process of non-stop casting of steel. They are part of the components of refractories to a steel casting slide gate. They are an integral replaceable part of the nest block.

In general, Learn more about the differences between ladle nozzle and tundish nozzle by reading this article. What's more, Get an in-depth look at the difference between ladle furnace and tundish furnace. If you are interested in refractory nozzle and other refractory products, welcome to view our factory to know more.

Article Source: What are the difference between tundish nozzles and ladle nozzles in steel making
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

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How to manufacture high alumina cement

 This article introduces the advantages and disadvantages of high alumina bricks. Read this article to learn about the application areas and product features of high alumina brick. What's more, You can know more details about difference between High Alumina Cement and Ordinary Portland Cement.

High Alumina Cement (HAC), sometimes known as calcium aluminate cement (CAC) or aluminous cement, is composed of calcium aluminates, unlike Portland cement which is composed of calcium silicates. It is manufactured from limestone or chalk and bauxite (Special clay having extremely high alumina content).

High Alumina Cement including lime, they are ground into cement clinkers in a process called fusing or sintering. Its popularity rose when the properties of this cement such as rapid strength gain and easy to manufacture were found out and widely used for precast concreting. High alumina cement is mostly used to manufacture structural concrete such as pre-cast beams.

High Alumina Cement

The process of manufacture of High Alumina Cement

The process of manufacture of High Alumina Cement is different compared to that of ordinary portland cement. Bauxite and lime are used as the raw material. The raw materials are mixed in the required proportion and grinded into small fragments of 100 mm. These lumps are fed in kiln and heated up-to their fusion point which is 1600°C. The molten material fall down on the steel plate and it is send to cool down in rotary kiln. These clinkers are then grounded finely in tube mills unto the fineness not less than 2250 cm2/gram is achieved.

High alumina cement is manufactured by sintering or fusing a mixture in suitable proportions, of alumina and calcareous materials and grinding the resultant product to a fine powder.

There are two main elements used to make high alumina cements limestone and bauxite. These two ingredients were charged into the furnace.

The furnace is fired with pulverized coal or oil with a hot air blast. The fusion process in the furnace generally takes place at a temperature of about 1550-1600°C.

The cement is maintained in a liquid state in the furnace. Then after the molten cement is filled in molds and cooled.

These castings are known as pigs. After cooking this molten cement it looks like a dark, fine gey compact rock resembling the structure and hardness of basalt rock. The pigs of fused cement, after cooling are crushed and then ground in tube mills to a fineness of about 3000 sq. cm/gm.

The complete process of High Alumina Cement production step by step:

At first, use the chemicals Bauxite and lime as raw materials and crush them both into small proportions. Each lump must be less than 100 mm in size.

1.Put these small fragments in a furnace

2.Now maintain the temperature of heat between 1500-to-1600-degree C.

3.The melted material fell on the steel plate

4.Wait for the molten material to little cool down

5.Place this molten material into vessel

6.This form of cement will now look like a rock after cooling down and turns into a light grey colour

7.We will now break this cement rock into small chunks

8.Every chunk must be crushed till it turn to a fined powder form of cement

9.In last we will go through separation or filtration process by the use of separating funnel and magnetic separators to separate metallic iron and other impurities from the cement

10.This refined powder or form of cement is High Alumina cement.

Advantages of High Alumina Cement

The advantages of High Alumina Cement are as follows,

1.Due to the more setting time, time for mixing and placing is more.

2.The resistance for the chemical action is good.

3.Can withstand high temperature.

4.Frost action is low as the heat evolved is more during setting.

5.High alumina cement is very reactive and has very high compressive strength.

6.High resistant to fire.

Disadvantages of High Alumina Cement

The disadvantages of high alumina cement are as follows,

1.As the heat required for the manufacture of this cement is more, the manufacturing cost of this cement is high.

2.As the fineness is kept not less than 2250 cm2/gram, which is very fine. Care to be taken that it doesn't come in contact with human eye or mouth.

3.As the heat evolution while setting is high, it cannot be used in mass concreting works.

High Alumina Cement Raw Materials

Raw Material	Percentage
Bauxite	40 %
Lime	40 %
Iron oxide	15 %
Ferric oxide, silica, magnesia	Little

High Alumina Cement Applications:

1.It is frequently utilized in sewer infrastructure and maritime building because of its quick hardening and strength properties.

2.Refractory concretes that need higher strength at very high temperatures, also use this cement.

3.High alumina cement is also used in refractory concretes where it requires more strength at very high temperature.

4. In construction concretes, where rapid strength development is required, even at low temperatures.

5. As a protective liner against microbial corrosion such as in sewer infrastructure

6. As a component in blended cement formulations, for various properties such as ultra-rapid strength development and controlled expansion are required.

7. In sewer networks for their high resistance to biogenic sulfide corrosion.

Characteristics of High Alumina Cement:

1.This cement is excellent resistance to chemical attacks.

2.There is a pH problem.

3.It is used to construct water and sewage pipes, factory drains, coastal constructions, and manufacturing chimneys due to its strong resistance to chemical corrosion.

4.There is a high refractive index in the cement issue.

5.It is highly resistant to sulfuric acid.

6.This cement’s rapid cementing property.

7.Due to its ability to establish a ceramic bond at high temperatures, it serves as a bonding agent when added to refractory castable.

Hydration of High Alumina Cement:

The important reaction during the setting of the high alumina cement (HAC) is the formation of monocalcium aluminate decahydrate (CAH10), dicalcium aluminate octahydrate (C2AH8), and alumina gel (Ahn).

These aluminates provide high strength to HAC concrete but they are metastable and at normal temperature convert gradually to tricalcium alumina hexahydrate (C3AH6) and gibbsite which are more stable.

Difference between High Alumina Cement and Ordinary Portland Cement

As compared to ordinary portland cement, high alumina cement has the following differences:

High Alumina Cement	Ordinary Portland Cement
High alumina content about 40 %
Higher resistance to sulphate attack	OPC is not much resistant to sulphate attack
Calcium hydroxide is absent in the hydrated products of high alumina cement	Calcium hydroxide and CSH gel are the main hydration products of OPC
No free lime is produced after setting and hardening even at high temperatures	At high temperatures, Ca(OH)2 decomposes producing free lime
Absence of free lime does not make HAC unsound when exposed to moisture or water	Free lime makes OPC unsound when exposed to moisture
Used for making refractory lining in furnaces	Used for normal construction purposes

More details about High Alumina Cement:

What is high alumina cement used for?

Generally, this refractory product is widely used in sewer infrastructure and marine construction. Besides, it is also used in refractory concretes for furnaces, boilers, kilns, and chimneys. This is due to its strength to withstand very high temperatures with proven durability.

Why is high alumina cement not allowed to be used structurally?

High alumina cement possesses properties like high early strength, rapid hardening even at low temperature, and durability to sulphate attack. But the conversion of HAC has made it unfit for structural use due to gradual strength loss.

Which raw material is used for high alumina cement?

High alumina cement is manufactured by fusing together a mixture of 40% bauxite , 40% lime and 15% iron oxide and ferric oxide, 5% silica, magnesia etc.

What is another name for high alumina cement?

aluminous cement

Calcium aluminate cements are cements consisting predominantly of hydraulic calcium aluminates. Alternative names are "aluminous cement", "high-alumina cement", and "Ciment fondu" in French. They are used in a number of small-scale, specialized applications.

How high alumina cement is made?

High Alumina Cement is manufactured by grinding the clinkers of alumina and calcareous material such as lime by fusing or sintering process. This cement is also known as calcium aluminum cement.

By reading this article, have In-depth understanding of the advantages and disadvantages of high alumina bricks. If you are interested in other refractory products or other furnace solutions, welcome to contact us anytime.

Article Source: How to manufacture high alumina cement
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

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The Development of Refractory Ramming Mass

 The ramming mass refers to ramming (manual or mechanical) method of construction, and hardened in the heating effect is higher than normal temperature under the unshaped refractory materials. 

By refractory aggregate, with certain gradation of powder, binder, additive water or other liquid after mixing.According to the material classification with high alumina, clay, magnesite, dolomite, zirconium and silicon carbide carbon refractory ramming material.

Refractory Ramming Mass Function: 

ramming material is made of silicon carbide, graphite, electric calcined anthracite as raw material, mixed with a variety of ultra-fine powder additives, fused cement or composite resin as the binder made of bulk cement.To fill the gap or stack cooling equipment and masonry masonry filler. 

Refractory Ramming Mass Types: 

The leveling layer with acidic, neutral and alkaline ramming material widely used in intermediate frequency coreless furnace core induction furnace, as if furnace ramming material used for melting aluminum and its alloys, melting of copper, brass, copper and bronze and copper alloy etc.

The carbon ramming mass as an example: according to the different type of blast furnace and the material design requirements of different carbon ramming material is mainly used for blast furnace carbon brick and bottom sealing gaps between plates and carbon bricks and the cooling wall, and filling the furnace bottom water cooling tube over the central line of the leveling and cooling wall, all parts are required by ramming carbon ramming after ramming mass has a certain strength and density, and filled every corner of a small gap, to achieve no leakage of hot metal and gas demand,Classification and construction: all ceramic ramming material consisting of material is divided into: clay, high alumina, carbon, magnesium and dolomite.

Refractory Ramming Mass Advantages:

High erosion resistance.

High bonding strength.

Short lead time.

Free engineering services to guarantee service life.

Ramming mass is used in various industrial places for manufacturing of many refractory materials. It is prepared with great precision using modern techniques and quality materials. Corrosion resistant with a high level of thermal stability, it offers maximum output and last longer. It can be used in lining of iron, lining the trough of blast furnaces, lining of induction furnaces, used as insulation for rapid drying. Also, available in a premixed form allows lesser wastage, consistent and longer lining and patching life.  Ramming mass is prepared using quality components and other raw material as per the industrial set standards and norms with great precision. The even and regular granule of the powder are appreciated by the clientele.

Neutral Ramming Mass VS Silica Linings

Silica ramming mass can safely be used up to an operating temperature of 1600 deg C. Since it expands very little, it is superior to both alumina and magnesia refractories to resist thermal shocks. Though silica lining has good endurance against thermal shock, it has poor resistance against steelmaking slags. Temperature control is very necessary for a satisfactory lining life.

The addition of right quantity of boric acid is very important for optimum life of lining. 

The quantity depends upon (i) temperature of liquid metal bath, (ii) chemical composition of quartzite mass, and (iii) thickness of crucible wall. 

Silica linings are the conventional lining solution widely used in both ferrous and non-ferrous foundries. Mainly made of crystalline silica and commonly known as acidic ramming mass, the typical binding agents that aid in the sintering of silica linings are boron-based. This refractory lining exhibits mainly low thermal expansion and have excellent thermal shock resistance. 

Neutral ramming mass are a unique, chemically neutral foundry solution that form joint-less linings. The in-situ spinels synthesise at high temperatures inside the refractory lining, creating a unique 3-layer structure. The outermost layer in contact with the molten metal is a hard, sintered surface, followed by an intermediate fritted layer. The innermost layer stays in a powdery form.

Neutral ramming mass

Lining wear and the causes of wear

The lining life of induction furnace lined with silica ramming mass depends upon the lining practice and operating practice of the furnace besides quality of the silica ramming mass. It is quite common to get inconsistent lining life of the furnace. There are cases when sudden failure of lining takes place. 

The main factors which affects the lining life of the induction furnace are 

(i) incorrect granulometry of the ramming mass, 

(ii) non-uniform distribution of the binding agent, 

(iii) superheating of the metal bath in the furnace, 

(iv) penetration of metal, 

(v) minimum slag free metal resulting in minimum erosion at slag line, 

(vi) loss of refractory powder, and (vii) topping/lining interface cracking

For the proper failure analysis in case of pre-mature failure of the refractory lining, it is important that proper records about output, working temperature, and other parameters are maintained. These records not only help in finding the cause of failure but also help in the continuous performance of the lining life.

Article Source: The Development of Refractory Ramming Mass
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