aluminabricks, Author at RS Kiln Refractory Bricks

Dec 10 2018

Silicon Carbide Mullite Bricks

Silicon Carbide Mullite Bricks Description

Silicon carbide mullite bricks are also called high alumina silicon carbide bricks. SiC mullite brick main mineral phase is SiC and mullite. It can be produced by SiC and bauxite clinker. During high temperature application in kilns, silicon carbide can be oxidized and produce SiO2, which can react will Al2O3 to form mullite (3Al2O3·2SiO2).The synthesized mullite can not only enhance brick’s density and strength, but also form protection film to prevent further oxidization of SiC. The un-reacted SiC can enhance thermal shock resistance, abrasion resistance and corrosion resistance of silicon carbide mullite bricks.

Silicon Carbide Mullite Bricks Characteristics

Abrasion Resistance

SiC mullite brick’s principle phases are high rigidity SiC, mullite and corundum, meanwhile, SiC mullite bricks has high structural density, its bulk density is between 2.7 and 3.0g/cm3. So SiC mullite bricks have good abrasion resistance. Silicon carbide mullite brick’s density, strength and abrasion resistance is significantly better than high alumina bricks and magnesia alumina spinel bricks.

Spalling Resistance And Thermal Shock Resistance

SiC in silicon carbide mullite bricks has high thermal conductivity, small thermal expansion rate, so SiC carbide mullite bricks have good thermal stability, max. thermal shock times can reach to 46 times(1100℃, water cooling).

Insulating Performance

Silicon carbide mullite brick’s thermal conductivity(≤2.3W·(m·K) is lower than spinel bricks, and thus have better heat preservation effect.

High Temperature Performance

SiC mullite brick’s refractoriness under load is above 1500℃, max. is 1690℃, can endure high temperature impact and won’t soften or deform.

SiC Mullite Bricks Physiochemical Index

Item	GM1650	GM1600	GM1550	GM1680
Al2O3 %	63	60	57	63
SiO2+SiC %	30	30	30	30
Apparent porosity %	17	17	19	17
Cold crushing strength Mpa	85	90	90	100
Refractoriness under load ℃ (0.2Mpa)	1650	1600	1550	1680
Thermal shock resistance(11oo℃, water cooling)	10	10	12	13
Bulk density g/cm3	2.65	2.60	2.55	2.65
Cold abrasion resistance cm3	5	5	5	5
Thermal conductivity(w/m·k)	1.7	1.7	1.7	1.7

Silicon Carbide Mullite Bricks Application

Due to silicon carbide mullite brick’s good abrasion resistance, high refractoriness and thermal shock resistance, it is popularly used in rotary cement kiln sintering zone, transition zone and so on, where material rolling friction, high temperature thermal stress, temperature fluctuation and material corrosion are severe.

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Dec 10 2018

Submerged Nozzle

Submerged Nozzle Description

Submerged nozzle ‘s top end connects to the bottom of tundish, bottom end extends into crystallizer, so steel liquid flows from tundish won’t expose to air. The advantages of submerged nozzle are: avoiding steel liquid splashing, reducing impurity entry and protecting steel liquid from oxidization.

Submerged nozzle’s working condition is very harsh, such as very strong thermal shock, steel liquid scouring and erosion, crystallizer protection slag intense corrosion. As protection slag is low melting point, low viscosity material which contains strong corrosive fluorite, K oxide and Na oxide, its corrosion to submerged nozzle is severer than long nozzle, submerged nozzle’s technical requirement is much higher than elongated nozzle.

Submerged Nozzle Types

Silica submerged nozzle is primary used in steel mills, but the corrosion rate is very quick, can only be used in those with lower continuous casting times. Quartz submerged nozzle is not suitable for high continuous casting level or special steel continuous casting mills. Composite submerged nozzle is improved on basis of molten quartz nozzle, slag line adopts composite refractory which has better corrosion resistance to improve service life.

To meet the quick development of continuous casting technique, alumina carbon submerged nozzle is designed. Its service life is significantly prolonged, but thermal shock resistance of alumina carbon submerged nozzle is not very good. To meet thermal shock resistance, some ratio of mullite and molten quartz are added into alumina carbon submerged nozzle. Composite submerged nozzle, such as alumina zirconia carbon submerged nozzle, zirconium boride submerged nozzle are developed, which have good slag corrosion resistance and steel liquid corrosion resistance.

Submerged Nozzle Physiochemical Index

Item	Composite submerged nozzle-1			Composite submerged nozzle-2		Quartz submerged nozzle
Item	Main body	Slag line	Purging part	Main body	Slag line	Quartz submerged nozzle
Material	Al2O3-C	ZrO2-C	Al2O3-C	Al2O3-C	ZrO2-C	Quartz
Al2O3 %≥	48	/	80	45	/	/
C %≥	30	15	15	20	12	/
ZrO2%	/	77	/	/	80	/
SiO2 %	≤15	/	/	≤20	/	≥99
Apparent porosity %≤	17	18	/	20	18	19
Cold compression strength Mpa ≥	17	/	/	16	/	40
Cold rupture strength Mpa	≥6	/	/	≥4	/	/
Thermal shock resistance/ times	≥5	/	/	≥5	/	≥5

For aluminum killed steel casting, nozzle will be blocked by clots, so argon blowing method can be used to avoid this problem, inner lining of submerged nozzle can adopt carbon free refractory and calcium zirconate to get better performance. Submerged nozzle also has another important problem, i.e., surface oxidation, which can make submerged nozzle lose structural strength and damaged. So, a layer of anti-oxidation material can be coated to the surface of submerged nozzle.

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Dec 7 2018

Continuous Casting System Stopper

Continuous Casting System Stopper description

Continuous casting system stopper is installed above tapping nozzle. Through adjusting the gap between stopper and nozzle, steel liquid flowing speed can be controlled. The earliest sleeve bricks of stopper are high alumina bricks or clay bricks. Stopper end is made by alumina carbon refractory. They need to assemble with steel structural controlling rod for using. The service life of combined stopper is not very high, usually less than 6 hours. The main damage reasons of stopper are: On one hand, steel structure is softened in long term high temperature environment and loses controlling effect, on the other hand, sleeve brick is corroded too quickly. To solve this problem, steel controlling rod should have good high temperature performance, sleeve brick should have excellent corrosion resistance and stopper end should properly match with nozzle bowl part.

Another method to solve the problem of combined stopper’s low service life is adopting integral stopper, i.e., alumina carbon integral stopper. Alumina carbon integral stopper is made by isostatic pressing molding, solidifying, mechanical processing and carbonizing, there is no metal rod in alumina carbon stopper and avoids the problem of metal rod softening. The service life of alumina carbon integral stopper can reach to 10h. But stopper end and nozzle bowl part will be scoured irregular and not smooth, it will cause difficulty for flow speed control, or even can’t close. That is key factor constraining the service life of alumina carbon stopper.

Continuous Casting System Stopper Physiochemical Index

Item		Chemical composition (w %)					Cold CS/Mpa ≥	Apparent porosity % ≤	High Temp. rupture strength Mpa	Thermal shock resistance /times
Item		Al2O3 ≥	C≥	ZrO2	SiO2	MgO	Cold CS/Mpa ≥	Apparent porosity % ≤	High Temp. rupture strength Mpa	Thermal shock resistance /times
Integral stopper		60	25	/	/	/	16	19	≥5	≥5
Integral stopper		55	23	/	/	/	15	/	≥4	≥5
Combined stopper	Sleeve brick	60	/	/	≤30	/	40	18	/	≥20
	Sleeve brick	42	/	/	≤52	/	40	18	/	≥20
	Stopper end	80	10	/	/	/	40	18	≥12	/
	Stopper end	75	10	≥6~9	/	/	40	6	≥12	/
Composite stopper	Main body	60	25	/	/	/	16	19	≥5	≥5
	Slag line	/	14	/	/	80	30	5	≥10	/
	Slag line	75	10	≥6~9	/	/	25	10	≥8	/
	End	/	5	≥90	/	/	/	/	/	/
	End	85	5	/	/	/	/	/	/	/

Continuous Casting System Stopper applications

For steel mills using converter to produce ordinary construction steel , steel liquid supply is sufficient, it needs the long service life of stopper, the longer the better. For steel mills producing special steel, different types of steel have different corrosion to stopper, so stoppers which can resist different kinds of steel liquid corrosion is needed. For this reason, slag line part of stopper adopts magnesia carbon refractory, stopper end part adopts alumina zirconia carbon refractory.

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Dec 7 2018

Iron Trough Castable

Iron Trough Castable Description

Different iron smelting factories have different design of blast furnace iron troughs, such as iron storing trough and non storing iron trough, single iron trough and multi iron troughs. Blast furnace iron troughs can also be divided into main trough, branch channel, swing channel and slag channel. Different types of refractory materials can be used as per the types of iron troughs. Iron storing troughs in middle and large scale steel mills usually adopt Al-Si-C series castable.

Iron Trough Castable Characteristics

Blast furnace iron trough should endure iron liquid and molten slag intense scouring, high temperature iron liquid and molten slag chemical corrosion & permeation. So iron trough and slag trough castable should have enough mechanical strength and corrosion resistance. Once there is damage in the trough, it should be patched as soon as possible, which requires iron trough castable has good flowability, few water addition quantity and can be quickly dried. Besides, iron trough lining’s temperature fluctuates greatly, so iron trough castable should also has excellent thermal shock resistance.

Iron Trough Castable Physiochemical Index

Item	DCTC-1	DCTC-2	DCTC-3	DCTC-4
Material	Alumina silicon carbide carbon castable	Alumina silicon carbide carbon castable	Alumina silicon carbide carbon castable	High alumina silicon carbide castable
Application	Main trough slag line	Main trough iron line	Main trough iron line	Main trough slag line
Al2O3 %	60	83	77	56.9
SiC %	37	12	11	32
SiO2 %	2.5	2.5	/	/
C %	1~3	1~3	2	2
Bulk density g/cm3(1450℃,3h)	2.78	2.98	2.84	2.69
Compression strength Mpa(1450℃,3h)	50	50	35.8	/
Reheating linear change rate %(1450℃,2h)	-0.2~0.6	-0.2~0.6	-0.2~0.6	-0.1~0.2

Item	DCTC-5	DCTC-6	DCTC-7	DCTC-8
Material	Alumina silicon carbide carbon castable	Alumina silicon carbide carbon castable	High alumina silicon carbide castable	High alumina silicon carbide castable
Application	Main trough cover top	Main trough cover sides	Iron trough	Slag trough
Al2O3 %	65.3	67.1	49.1	60.4
SiC %	15	15	9.33	14
SiO2 %	/	/	/	/
C %	/	/	/	1~3
Bulk density g/cm3(1450℃,3h)	2.78	2.98	2.84	2.69
Compression strength Mpa(1400℃,3h)	2.52	2.56	2.38	2.68
Reheating linear change rate %(1400℃,3h)	0.22	±0.35	-0.12	±0.5

So alumina silicon carbide carbon castable is mainly used for the casting of blast furnace iron trough. Alumina silicon carbide carbon castable’s main materials are fused corundum(or sintered corundum, special grade bauxite clinker), graphite contains 90%~95% fixed carbon, silicon carbide and so on. During construction, additives should be added and fully mixed before casting. For slag trough, lower grade of alumina silicon carbide carbon castable can be used, It can not only meet production requirement but also has better economic benefits. High alumina silicon carbide castable, which has excellent abrasion resistance is the best choice for slag line.

In recent years, quick dry Al-SiC-C castable is developed for casting houses which only have one iron running trough. The development of self flow Al-Si-C castable brings lots of convenience for casting construction. The unit refractory consumption of per ton iron is significantly decreased with the improvement of castable quality.

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Dec 6 2018

Non-Stick Aluminum Castable

Non-Stick Aluminum Castable Description

Non-stick aluminum castable is mainly used in aluminum smelting furnace, aluminum press casting heat preserving furnace and so on. Although the melting point of aluminum is not high, only about 660℃, aluminum liquid has low viscosity, high permeation ability and high activation property, which makes it have drastic corrosion to refractory furnace lining.

The Damage Mechanism Of Refractory Lining

Aluminum liquid can react with SiO2 in Al2O3-SiO2 series refractory material and produce Al2O3+Si. So the structure of Al2O3-SiO2 refractory will be destroyed, meanwhile, impurity Si will also contaminate aluminum liquid.
Aluminum liquid can infiltrate into refractory material pores, increases the contacting area of refractory material and change the composition. When the infiltration reaches to a certain depth, accompanied with the reaction of aluminum and SiO2, refractory material will have structural spalling.

Non Stick Aluminum Castable Property

To solve this problem, refractory material contacting with aluminum liquid should adopt non-stick aluminum castable. Non-stick aluminum castable has high density(low porosity), good high temperature, middle temperature and room temperature strength, and the strength is positively correlated to temperature. Meanwhile, non-stick aluminum furnace castable has good volume stability at different temperature. With the addition of ultra micro powder component, the porosity of non-stick aluminum processing castable is lower than 10%, the average pore aperture is only 0.5μm. So aluminum liquid can’t permeate into non-stick aluminum castable lining. What’s more, composite additives added in castable can increase aluminum liquid’s contact angle with castable lining and significantly strengthen lining’s aluminum liquid permeation resistance.

Non-Stick Aluminum Castable Physiochemical Index

Item		BZL-1	BZL -1A	BZL-M	BZL-F	BZL-G
Chemical composition	Al2O3≥	60	65	65	70	80
	Fe2O3≤	0.6	0.5	0.4	0.4	0.3
	BaO+ZnO+B2O3≥	3	3	3	4	4
Bulk density g/cm3≥		2.4	2.5	2.65	2.7	2.8
Compression strength Mpa≥	110℃*24h	35	40	40	45	45
	1300℃*16h	40	45	45	50	50
Rupture strength Mpa≥	110℃*24h	5	10	10	12	14
	1300℃*16h	10	13	13	15	16
Linear change rate % (1300℃*3h)		0～+0.2	0～+0.2	0～+0.2	0～+0.1	0～+0.1

Non-Stick Aluminum Castable Application

Non-stick aluminum castable is specially developed for aluminum processing industry, it is mainly used in aluminum melting furnace wall, furnace bottom, degassing tank, launder and fore-tank. No stick aluminum castable is also used for the furnace lining of keeping furnace, aluminum liquid heat preserving furnace, aluminum ladle and so on. Especially suitable for the integral casting of heat preserving furnace and lining of high purity aluminum smelting equipment. Non-stick aluminum castable synthesizes the characteristics of organic binders and inorganic binders, added in certain quantity of new type composite material, can effectively avoid the infiltration of aluminum liquid and significantly prolong the service life of refractory castable lining.

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Dec 6 2018

Coating Resistant Silicon Carbide Castable

Coating Resistant Silicon Carbide Castable Description

Silicon carbide castable is also call coating resistant silicon carbide castable. It takes SiC as main raw material, pure calcium aluminate cement as binder, added with high efficient water reducing agent and ultra micro powder. Silicon carbide is high grade synthesized refractory material, has a wide range of application in refractory industry. Due to its particular characteristic, SiC has very low adhesion ability with cement raw material.

Coating resistant castable’s aggregate mainly compromise low bauxite aggregate, scrap ceramics, scrap electroceramics, SiC and so on. Aluminate cement is usually used as binders of SiC coating resistant castable. Usually, cement raw material is hard to adhere to the surface of SiC castable, so the chance of cement raw material agglomeration at kiln tail is greatly decreased. The application of silicon carbide castable in cement kiln, can avoid the coating of cement in kiln, so the output of cement production line will raise correspondingly.

Coating Resistant Silicon Carbide Castable properties

Coating resistant SiC castable has good abrasion resistance and corrosion resistance.

Good high temperature mechanical strength, high thermal conduction coefficient.

Small linear expansion coefficient, excellent thermal shock resistance.

Won’t react with cement raw material.

Silicon carbide castable has good coating resistance, can significantly decrease coating times.

Coating Resistant Silicon Carbide Castable physiochemical index

Item	SiC-30	SiC-50
Al2O3 % ≤	35	25
SiC ≥	30	50
Bulk density g/cm3(110℃,24h)	2.40	2.50
Cold compression strength Mpa (110℃,24h) ≥	80	70
Cold rupture strength Mpa (110℃,24h) ≥	9	8
Permanent linear change rate % (1100℃,3h)	±0.4	±0.4
Alkali resistance grade	I	I
Max. working temperature ℃	1350	1400
Water addition %	6.0~7.0	5.5~6.5

Coating Resistant Silicon Carbide Castable Applications

Based on SiC content, coating resistant SiC castable can be classified into two types: one is SiC-30, which’s SiC content is no less than 30%, the other is SiC-50, which’s SiC content is no less than 50%. Both SiC-30 and SiC-50 SiC castable can be used in places of new type middle large scale dry cement kiln pre-heater feeding slope, ascending flue, decomposing furnace cone and so on, where cement coating is easy to form.

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Dec 5 2018

Tabular corundum castable

Tabular Corundum Castable

Tabular corundum castable is high grade monolithic refractory which is composed of tabular corundum aggregate, fines and high alumina binder. Based on different applications, different kinds of ingredients can be added into tabular corundum castable to enhance its thermal, chemical and mechanical performances. For example, chrome corundum castable which has high refractoriness can be applied in carbon black furnace, coal gasifier lining. zirconia corundum castable which has excellent glass corrosion resistance is suitable for glass kiln. Composite corundum castable with specific composition can be used for various industrial kilns and furnaces such as cement rotary kiln, nonferrous metal smelting furnace, steel industry and so on.

Tabular Corundum Castable Property

High mechanical strength, good abrasion resistance.

Excellent thermal shock resistance, creep resistance.

High refractoriness, good high temperature volume stability.

Excellent Slag corrosion resistance, chemical corrosion resistance.

Convenient for construction, maintenance and patching.

Tabular Corundum Castable Physiochemical Index

Item	Tabular corundum castable	High alumina castable
Model	GYJ-90	GLJ-80
Refractoriness / ℃	1810	1790
Bulk Density / g/cm3 ≥	2.85	2.85
Al2O3 % ≥	90	80
Thermal shock resistance (1100℃) /times ≥	80	70
Alkali resistance >	2	1
110℃ Wear resistance ，≤	6	6
Rupture Strength，(110℃, 3h) Mpa ≥	13	10
Compressive Strength (110℃, 3h) Mpa ≥	110	100

Corundum Castable Application

Corundum castable has a wide range of application in various kinds of industrial kilns and furnaces, one main application of tabular corundum castable is iron and steel industry. For example, for the casting of steel ladle working lining, sliding gate valve and tapping nozzle, long nozzle, submerged nozzle, tornado tank working lining, purging plug, pocket brick, iron runner and the integral casting of electric arc furnace cover triangle zone. Other applications of tabular corundum castable are rotary kiln front mouth, coal injection tube, circulating fluidized bed boiler, RH furnace immersion tube outer lining, petrochemical industry high temperature catalytic cracking reactor working lining, etc.

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Steel industry refractories

Dec 4 2018

RH and DH Refractory

RH is vacuum argon blowing recycling degassing equipment for steel liquid refinery, and DH is vacuum degassing refinery equipment. By blowing high speed argon in immersion tube and vacuum chamber upper part, steel liquid in ladle will flow into bottom side of vacuum chamber and be degassed, and then flow back to ladle through the other dipping tube. Through vacuum recycling degassing, harmful gases such as nitrogen, hydrogen in steel liquid can be removed. If oxygen blowing is adopted, carbon content can be decreased to a very low extent. RH and DH refinery equipments are mainly used for low carbon steel, low nitrogen steel and low hydrogen steel. Under those working conditions, furnace lining refractory materials should have good scouring resistance, vacuum resistance and thermal shock resistance.

RH refinery

In concern of cleaning steel production, refractory materials should better contain no carbon, nitrogen and hydrogen. Usually, vacuum chamber can use magnesia chrome bricks, inner side of immersion tube can use magnesia chrome bricks, while the outer side can adopt alumina magnesia spinel castable. The service life of magnesia chrome bricks at vacuum chamber upper part can reach to 2000 times or more, but the lower part is only about 500 times. The service life of immersion tube is about 100 times, varies with working condition and maintenance quality.

RH furnace structure

Magnesia alumina spinel bricks can be a good replacement of magnesia chrome bricks, but the corrosion resistance is not as good as magnesia chrome bricks. Another replacement of magnesia chrome bricks is low carbon magnesia carbon bricks, which has good performance price ratio compared with MgO-Cr2O3 bricks. RH immersion tube can be integrally casted by magnesia alumina spinel castable or magnesia zirconia castable. Through patching, the service life of integrally casted immersion tube can reach to or exceed magnesia chrome bricks lining.

RH Refractory Material Physiochemical Index

Item	Basic mortar	Alumina magnesia castable	Insulating brick	Calcium silicate board	Direct bonded magnesia chrome brick
Application	Masonry of magnesia chrome brick	Immersion tube, vacuum chamber upper part	Vent pipe, vacuum chamber	Vacuum chamber	Vacuum chamber
MgO %	92	>2	/	/	80
Al2O3%	/	>90	51.2	/	/
Fe2O3 %	/	/	1.7	/	/
Cr2O3 %	/	/	/	/	6~13
SiO2 %	/	/	/	/	1.98
Apparent porosity %	/	/	/	/	15
Bulk density g/cm3	/	≥2.90	≤0.9	0.23	3.06
Compression strength Mpa	/	≥40(11o℃)	7.37	≥0.5	59.2
Rupture strength Mpa	/	≥8.4(110℃,24h)	/	0.52	≥6.0(1200℃)
Reheating linear change rate %	/	±0.5(1500℃,3h)	-0.43	1.5 (1500℃,3h)	/
Refractoriness ℃	>1790	>1790	/	Max.1000	/

Item	Magnesia gunning mix	Magnesia chrome gunning mix	Magnesia injection mix	Magnesia carbon brick	Magnesia spinel precast block
Application	Vacuum chamber lower part, immersion tube	Immersion tube, vacuum chamber upper part	Immersion tube, vacuum chamber upper part	Vacuum chamber lower part, immersion tube	Vacuum chamber lower part, immersion tube
MgO %	≥85	≥70	≥70	≥85	80
Al2O3%	/	4	3	F.C≤5	10
Fe2O3 %	/	≤5	≤5	/	/
Cr2O3 %	/	≥5	≥5	/	/
SiO2 %	≤6	≤4	≤5	/	≤2
Apparent porosity %	≤24	≤24	≤24	≤4	≤15
Bulk density g/cm3	≥2.2	≥2.3	≥2.4	≥3.10	3.06
Compression strength Mpa	≥25 (11o℃)	≥20(11o℃)	≥20(1600℃,3h)	≥30 (11o℃)	≥40 (11o℃)

Item	Magnesia chrome brick	Magnesia chrome brick	Magnesia chrome brick	High alumina castable	Direct bonded magnesia chrome brick
Application	RH vacuum chamber upper part	RH lower part, recycling tube and immersion tube	OB gunning machine for RH	Vacuum chamber	Immersion tube
MgO %	80	76.9	69.9	/	65
Al2O3%	/	/	/	92.8	/
Fe2O3 %	/	/	/	/	/
Cr2O3 %	8.4	10.9	18.67	/	19
SiO2 %	1.6	1.46	1.52	/	≤2
Apparent porosity %	16	15	15	/	15
Bulk density g/cm3	3.05	3.11	3.00	2.79(1500℃,3h)	≥3.12
Compression strength Mpa	60	66	61	≥30(1500℃,3h)	60
Rupture strength Mpa (1480℃)	10	7.6	9.1	≥8.4（110℃）	60
Reheating linear change rate %	/	/	/	-0.27 (1500℃,3h)	-0.27 (1500℃,3h)
Refractoriness under load ℃	>1650	>1700	>1700	/	>1700

Item	RH gunning mix	RH injecting mix	CAS immersion tube castable	KIP spray gun castable
Application	Masonry of magnesia chrome brick	Immersion tube, vacuum chamber upper part	Vent pipe, vacuum chamber	Vacuum chamber
MgO %	/	/	≥4	/
Al2O3%	≥92	≥92	≥87	≥95
Refractoriness ℃	>1790	>1790	/	/
Bulk density g/cm3(110℃,24h)	≥2.90	≥2.60	≥2.95	≥3.00
Compression strength Mpa(1500℃,3h)	≥50	/	≥40	/
Rupture strength Mpa (110℃,24h)	≥4.0	≥4.0	/	≥4.0
Linear change rate %(1500℃,3h)	±1.0	±1.0	/	0~2.0

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Steel industry refractories

Dec 4 2018

Nozzle Refractory For Continuous Casting System

Nozzle Refractory Description

Nozzle series refractory can be divided into long nozzle, metering nozzle, submerged nozzle and separation ring.

Long Nozzle

Long nozzle is the connection part between steel ladle and tundish. Head end of long nozzle connects to steel ladle down nozzle, bottom end embeds into tundish steel liquid. Long nozzle can keep steel liquid from contacting with air during transferring from ladle to tundish, so steel liquid won’t splash, impurity won’t enter into steel liquid. The working condition suggests that long nozzle should not only endure strong thermal shock, steel liquid scouring and corrosion, but also suffer the corrosion of tundish cover flux. With the increasing requirement on steel quality, protecting casting ratio is continuously growing, so long nozzles using ratio is surging.

elongated nozzle

Quartz long nozzle is earliest used, which has very low linear expansion rate or nearly no thermal expansion, excellent thermal shock resistance, but it’s corrosion resistance is weak, especially for the casting of special steel such as high Mn steel, the service life is even shorter. With the developing of continuous casting technique, especially the casting of special steel, quartz long nozzle can also have unfavorable effect on steel quality, so new type of alumina carbon long nozzle is developed. Alumina carbon long nozzle’s service life is significantly longer than quartz long nozzle, but alumina carbon long nozzle’s main components are corundum, mullite, graphite and molten quartz, although mullite and quartz can large scale increase thermal shock resistance, the corrosion resistance to Mn steel and other special steel is not very good.

long nozzle

To solve this problem, composite long nozzle is developed, i.e., slag line magnesia carbon material, zirconia carbon material, main body adopts alumina zirconia carbon material, to meet low carbon steel casting needs, inner layer adopts alumina magnesia and Sialon ceramic carbon free material.

In recent years, unshaped long nozzle is also developed. Casting molding method is used to replace isostatic pressing molding for the production of alumina carbon quartz long nozzle and alumina magnesia long nozzle.

Long Nozzle Physiochemical Index

Item	Alumina carbon long nozzle	Alumina carbon long nozzle		Quartz nozzle	Quartz nozzle	Al2O3-C long nozzle
Item	Alumina carbon long nozzle	Main body	Purging ring	Quartz nozzle	Quartz nozzle	Al2O3-C long nozzle
Al2O3 %	43.81	≥40	≥85	/	/	≥50
F．C %	30.65	≥27	/	/	/	≥25
SiO2 %	/	/	/	≥99	≥99	/
Bulk density g/cm3	2.24	/	/	≥1.82	≥1.84	/
Apparent porosity %	17	≤20	/	≤19	≤18	12~20
Compression strength Mpa	25.2	≥20	/	≥40	≥40	≥15
Rupture strength Mpa	7.82	≥6	/	/	/	≥4
Air flow rate L/min	229	/	100	/	/	/
Thermal shock resistance/times	229	/	100	/	/	/

Item	Alumina carbon quartz long nozzle	Alumina magnesia carbon long nozzle		Alumina zirconia carbon long nozzle	Alumina carbon long nozzle
Item	Alumina carbon quartz long nozzle	Main body	Slag line	Alumina zirconia carbon long nozzle	Main body	Purging part
Material	Alumina carbon	Alumina carbon	Magnesia carbon	Alumina zirconia carbon	Alumina carbon compound	Alumina carbon compound
Al2O3 %	50	≥40	MgO, 74	≥40	50	90
F．C %	30	≥27	25	≥27	31	/
SiO2 %	14	/	/	/	/	/
ZrO2 %	/	/	/	6~10	/	/
Bulk density g/cm3	2.50	2.38	2.40	≥2.50	2.25	/
Apparent porosity %	14	≤20	16	≤18	17	/
Compression strength Mpa	/	≥20	/	≥20	24.4	/
Rupture strength Mpa	/	≥6	/	≥6	/	/
Air flow rate L/min(0.1Mpa)	/	/	/	/	/	210
Thermal shock resistance/times	/	≥5	/	≥5	5	/

Metering Nozzle

Metering nozzle is mainly used for the continuous casting of small billet. It is installed at the bottom of tundish. Metering nozzle should not have diameter enlargement or erosion under the strong scouring and corrosion of steel liquid. Inserting metering nozzle’s inner layer is made from zirconia ceramic refractory, which has excellent performance, outer layer is made from high alumina refractory. Inserting metering nozzle’s performance cost ratio is very high, so is popularly used. Integral metering nozzle is made by single type of refractory material, but performance cost ratio is not so high as inserting type metering nozzle. Worthy to be mentioned is that, a lot of steel mills insert pocket bricks and metering nozzles together and form a whole body, which is convenient for construction and safer for production.

metering nozzle

To prolong metering nozzle’s service life, zirconia content and zirconia ceramic’s density should be improved. The content of zirconia is raised from 65% to 94%, the density is increased from 3.4g/cm3 to 5.0g/cm3. To improve thermal shock resistance, semi stable zirconia is usually adopted, CaO is used as stabilizer.

zirconia metering nozzle

Metering Nozzle Physiochemical Index

Item	DJ-65	DJ-70	DJ-75	DJ-80	Zirconia metering nozzle	Zirconia metering nozzle	WG-70	WG-80
Position	Whole body and inner core						Outer layer and pocket block
ZrO2%≥	65	70	75	80	90	94	/	/
Al2O3 %	/	/	/	/	/	/	≥70	≥80
Apparent porosity% ≤	20	21	21	22	22	23	19	19
Bulk densityg/cm3≥	3.70	3.75	3.90	4.10	4.30	4.50	2.60	2.80

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Dec 3 2018

LF-VD Furnace Refractory Material

LV-VD furnace is steel liquid refinery equipment, which’s working condition is very harsh, should endure all kinds of high temperature corrosion, chemical corrosion, mechanical stress and thermal stress. So high quality refractory products should be adopted in according parts of LF-VD furnaces.
Magnesia carbon bricks are mainly used at furnace bottom and working lining. Corundum precast block which has high mechanical strength is mainly used at furnace bottom impacting zone. Magnesia chrome ramming mass is mainly used at furnace wall corner. Magnesia chrome mortar can be used for the masonry of magnesia chrome bricks.

LF-VD Furnace Refractory Material Physiochemical Index

Name	Magnesia carbon brick	Corundum precast block	Magnesia mortar	Magnesia chrome ramming mass	Magnesia carbon brick
Application	Bottom, wall working lining	Bottom impacting zone	Steel ladle working lining	Wall corner	Below slag line, free surface working lining
MgO %	92.5	/	96	52	92.5
CaO %	2.5	/	2.2	Cr2O3,19	2.5
Fe2O3 %	4	/	0.3	19	4
SiO2 %	/	/	1	0.5	0.6
Al2O3 %≥	/	97	/	6	/
F.C % ≥	5	/	/	/	10
Apparent porosity %	≤7	/	/	/	<7
Bulk density g/cm3 ≥	3.07	2.98	/	/	2.98
Compression strength Mpa	>.40	80	/	25(110℃)	>30

Name	Magnesia carbon brick	Magnesia chrome brick	Magnesia chrome mortar	Magnesia castable (ramming mass)	Chrome silica ladle filler sand
Application	Slag line working lining	Slag line permanent lining	Magnesia chrome brick	Ladle nozzle	Tapping hole
MgO %	96	60	52	91	6~12
CaO %	2.3	Cr2O3, 18	Cr2O3, 19	2.0	Cr2O3 >30
Fe2O3 %	0.3	14	19	5.8	20
SiO2 %	1.2	0.5	0.5	0.5	30
Al2O3 %≥	/	6	6	0.3	5~10
F.C % ≥	10	/	/	/	/
Apparent porosity %	≤7	<15	/	/	/
Bulk density g/cm3 ≥	3.00	3.26	/	/	/
Compression strength Mpa	>30	>30	/	30(110℃)	/

Name	Corundum block	Magnesia block	Corundum brick	Magnesia brick	Corundum mullite brick
Application	Purging plug, sleeve brick, pocket block	Purging plug, sleeve brick, pocket block	Purging plug, sleeve brick, pocket block	Dispersive type Purging plug	Purging plug core plate
MgO %	/	97	/	97	/
CaO %	1.8	1.7	2.4	1.9	/
Fe2O3 %	/	/	/	/	/
SiO2 %	0.1	0.6	0.1	0.5	9
Al2O3 %≥	88	/	97	/	90
F.C % ≥	/	/	/	/	/
Apparent porosity %	/	<25	/	26	/
Bulk density g/cm3 ≥	3.22	2.75	3.00	2.60	2.95
Compression strength Mpa	>60	>30	>50	>30	>60
Thermal conductivity w.(m.K)^-1(1000℃)	/	3.0	2.8	3.0	/

Name	Alumina magnesia castable	Alumina chrome castable	Corundum castable	Magnesia chrome castable	Alumina chrome chamotte
Application	Purging brick surrounding	Purging brick surrounding	Purging brick surrounding	Lower Dispersive purging brick	Purging brick
MgO %	8	/	/	77	/
CaO %	1	1.8	2.4	/	/
Cr2O3 %	/	10	/	12	2.0
SiO2 %	0.1	/	0.1	/	7
Al2O3 %≥	88	88	97	/	84
F.C % ≥	/	/	/	/	/
Apparent porosity %	/	/	/	26	/
Bulk density g/cm3 ≥	3.00	3.22	3.00	2.60	/
Compression strength Mpa	>60	>60	>50	>30	/
Rupture strength Mpa(1400℃)	12	15	8	/	/

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Author: aluminabricks

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