Factors affecting the quality of tundish repair

 

1. Loose Wall

The looseness of the tundish wall is mainly reflected in the contact position between the tundish wall and the bottom of the tundish. The looseness of the wall is manifested in two forms: one is that it extends longitudinally from the position of the wall to form an irregular surface; The other is that the elongated powder falls down to form a "slit shape". There are two reasons for the looseness: one is that the binder volatilizes, resulting in a decrease in the overall bonding strength, especially the outermost one; the other is that the fine powder containing resin does not wrap the particles, which eventually causes slag to fall off easily. The low-temperature baking strength and medium-temperature strength of the dry-type material can be better improved by mixing boron glass powder and phenolic resin in the magnesium dry-type material.

Based on the site conditions, it was found that the reasons for the low quality of the tundish repair were as follows:

(1) The tundish fabric was unreasonable. The ratio of the binder in the current tundish is relatively low, and there is a phenomenon of piled up and concentrated distribution during the construction of the masonry, which leads to the segregation of large-grained magnesia in the dry material.

(2) The vibration time of the wrapped tire is long. At present, 4 motors are used for tire wrapping in the tundish. In order to increase the compactness at the position of the slag line, the vibration time is 15 minutes. Although the bulk density of the tundish dry material is increased, the lower dry material aggregate and powder are prone to separation, and the phenomenon of "bridging" between the dry material is prone to occur, causing the bag wall to loosen.

(3) The lower baking temperature of the tundish is low. The flame of the burner cannot reach the bottom, the temperature of the upper part of the tire is high, and the temperature of the lower part is relatively low, resulting in insufficient reaction temperature and low strength of the dry material that is about to harden. But still relatively loose.

2. Cracks in cladding wall

Horizontal stripes appear on the bag wall at the head of the middle bag. The dry material thickness at this position is 110 mm, and the crack depth is 40 mm. The main reason is that the current release agent is applied once, the thickness is only 0.1-0.2 mm, and the application is uneven, causing the tundish dry material to stick to the tire, and cracks to the dry material after the tire is started. Stress concentrations were created during lifting of the tire mold, which in turn caused surface cracks.

3. The shape of the upper nozzle does not meet the requirements

The current operating procedures for repairing packages only require that no sundries should be mixed in the nozzle. During operation, workers only use waste woven bags to plug in the nozzle, there is no uniform standard, and there is no reasonable mold, resulting in debris often remaining in the nozzle, and the shape of the tundish upper nozzle is irregular.

Wanhao is a manufacturer who is specialized in designing various kinds of furnace and making refractory products for electric furnace, ladle, tundish, blast furnace, AOD furnace, IF furnace, etc.

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Cold repair of EAF bottom ramming material

 1.First, thoroughly remove the steel slag, residual steel, steel and impurities infiltrated into the cracks on the repair surface. If the refractory material is pulverized by water, it should be completely removed until the refractory brick is exposed.

2.After the slag line is replaced, place the bottom of the EAF, hoist the ramming material into the EAF, and distribute the knotted material on the repaired surface as required to form a material layer with a height of about 150mm until it is covered with the repaired surface.

3.Distribute the material evenly, and use a special air vibration fork to poke each part of the material layer from the center of the molten pool to the EAF slope.

4.Repeat the operation twice until the EAF bottom ramming material is dense. Repeat the above steps until a suitable molten pool shape is formed.

We Changxing Refractory Material Co.,LTD is professional manufacturer and supplier of refractory materials for more than 30 years. Our high quality EAF bottom ramming mass are good sold to many countries say South Africa, Bangladesh, Indonesia, Malaysia, etc. Shall any interests, welcome to contact us. Our team would make best to be your reliable partner!

Article Source:Cold repair of EAF bottom ramming material
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How to choose insulation bricks

 How to choose insulating bricks Insulation bricks used in thermal equipment can greatly reduce heat loss and furnace weight and improve thermal efficiency and labor productivity.

For most thermal equipment, in order to save energy and improve working conditions, thermal insulation is necessary. However, for some equipment insulation is not necessary because of the pros and cons of thermal insulation. Therefore, the actual situation and the performance of thermal insulation bricks should be considered when selecting suitable thermal insulation bricks.

The thermal insulation bricks can be divided into the following types:

1) Fireclay insulation brick GB/T 3994-2005

2) High alumina thermal insulation brick

3) Mulite insulation brick

We Changxing Refractory Material Co.,LTD is professional manufacturer and supplier of refractory materials for more than 30 years. Our high quality refractory products are good sold to many countries say South Africa, Bangladesh, Indonesia, Malaysia, etc. Shall any interests, welcome to contact us. Our team would make best to be your reliable partner!

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Japan to close over 7 million tons of blast furnace capacity within two years

 In recent years, due to slowing steel demand, Japan has been shutting down blast furnaces or pushing to decommission older blast furnaces, and has committed to operational optimization, focusing on more competitive assets and products.

In September 2020, Nippon Steel Corporation, Japan's largest steel manufacturer, decommissioned its 1.5 million t/y (2,150m3) blast furnace No. 2 at its Kyushu plant (Yawata). Previously, blast furnace No. 2 was mothballed as part of a temporary production reduction plan due to a sharp drop in steel demand due to the new crown pneumonia epidemic. Meanwhile, Nippon Steel suspended operations at a smelting plant at its Kyushu plant, including bloom production facilities. In September 2021, Nippon Steel will completely shut down the upstream and midstream facilities of the Setouchi Plant (Ku), including the 2 million tons/year No. 1 blast furnace (2650m3) and the 1.6 million tons/year No. 2 blast furnace (2080m3). At the same time, the company also shut down a blast furnace (3700m3) with a capacity of 2.1 million tons/year at its Kansai plant (Wakayama).

Japanese steelmakers will continue to shut down blast furnaces. JFE Steel plans to close its refractory raw materials, steelmaking and rolling divisions at its East Japan plant (Keihin) in September 2023. Among other JFE Steel facilities, the 4.2 million tonne/year No. 2 blast furnace, a converter steelmaking workshop for slab production and an electric furnace steelmaking workshop for billet and bloom production will also cease operations. Nippon Steel plans to decommission a 4.2 million ton/year blast furnace (5270m3) at the East Japan Plant (Kashima) in early 2025, which will be the company's fifth blast furnace to be deactivated based on a capacity optimization plan.

In 2020, the No. 5 blast furnace of JFE Steel's West Japan Plant (Fukuyama) with a capacity of 3.6 million tons/year will be put into operation, and the expansion and upgrade of the 3.8 million tons/year No. 4 blast furnace of the West Japan Plant (Kurashiki) will be completed in 2021. However, the new capacity cannot fully compensate for the withdrawal of production capacity. It is estimated that Japan has withdrawn more than 7.3 million tons/year of ironmaking capacity since 2020, while the newly added capacity is about 4 million tons/year. An additional 8.4 million tonnes/year of ironmaking capacity will be shut down by 2026, following the successful implementation of planned projects.

Under the general trend of decarbonization, Japan may continue to reduce steel production capacity. However, it is difficult for Japan to completely abandon the mainstream blast furnace-converter production route, because there are certain difficulties in introducing a more sustainable DRI-electric arc furnace route, including the high cost of imported energy. Currently, the Japanese government and steelmakers are formulating a decarbonization roadmap and developing decarbonization technologies with the aim of significantly reducing their carbon footprint while preserving traditional production methods.

We Changxing Refractory Material Co.,LTD is professional manufacturer and supplier of refractory materials for more than 30 years. Our high quality refractory products are good sold to many countries say South Africa, Bangladesh, Indonesia, Malaysia, etc. Shall any interests, welcome to contact us. Our team would make best to be your reliable partner!

Article Source:Japan to close over 7 million tons of blast furnace capacity within two years
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Hot repair of EAF bottom ramming material

 

Hot repair of EAF bottom ramming material

1.Gradually reduce the loading amount. The last EAF of steel will completely discharge the molten steel. Immediately after tapping, the surface to be repaired is purged with oxygen, which is the key to affecting the repair of the entire EAF bottom.

 

2.Hoist the ramming material until the repaired surface falls, and move the crane to make it distributed reasonably. Hang in heavy objects for compaction.

 

3. The magnesia ramming material is used in a hot state, and the operation is convenient. The EAF slope of the magnesia-carbon brick slag line is maintained by the gunning process. After hot repair, it should be oven for more than 20min.

We Changxing Refractory Material Co.,LTD is professional manufacturer and supplier of refractory materials for more than 30 years. Our high quality EAF gunning material are good sold to many countries say South Africa, Bangladesh, Indonesia, Malaysia, etc. Shall any interests, welcome to contact us. Our team would make best to be your reliable partner!

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Brief introduction of gunning material

 The EAF gunning material bears the same high temperature and harsh working environment as the repaired furnace lining during the smelting process. Therefore, in addition to high refractoriness, erosion resistance, erosion resistance, spalling resistance, etc., the EAF gunning mix must also be compatible with the repaired furnace lining. The lining has good adhesion.

The gunning materials for electric furnaces include magnesia, magnesia-dolomite, magnesia-chromite, magnesia-carbon, magnesia-dolomite-carbon, etc., and some highly active seawater magnesia are used in the aggregate. To promote sintering and improve the density and strength of the gunning layer. In order to make the gunning material solidify quickly during the gunning operation and attach to the furnace lining at the same time, a small amount of additives are often added to the aggregate.

1.When adding Al, Mg and other low melting point metal powders for gunning, the oxidation heat of metal powder helps to increase the temperature, and harmless oxides are formed in the EAF gunning material to improve the adhesion between the gunning layer and the furnace lining.

2.Add spinel Cr2O3, SiC, B4C, etc. to improve the oxidation resistance and corrosion resistance of the material.

3.Add a small amount of organic fibers with a length of 1~5mm, and melt at low temperature to form air passages, which is conducive to the evaporation and discharge of water in the binder and prevents bursting.

4.Add 0.1~2mm and 10~40mm long metal fibers for tapping and other parts to improve the corrosion resistance of the gunning layer.

5.Add part of the slag of the metallurgical furnace to improve the adhesion and corrosion resistance of the EAF gunning mix.

We Changxing Refractory Material Co.,LTD is professional manufacturer and supplier of refractory materials for more than 30 years. Our high quality EAF gunning material are good sold to many countries say South Africa, Bangladesh, Indonesia, Malaysia, etc. Shall any interests, welcome to contact us. Our team would make best to be your reliable partner!

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Global steel demand growth expected to be lower in 2022

 The magnitude of the impact of the Russian-Ukrainian conflict varies by region, depending on the region’s direct trade and financial exposure to Russia and Ukraine. The conflict had a direct and devastating impact on Ukraine, and the European Union was also affected to a certain extent due to its high dependence on Russian energy. Not only that, the impact of the Russian-Ukrainian conflict has also spread globally due to rising energy prices (especially the refractory raw materials needed for steel production), resulting in continued disruption of supply chains in some regions, a problem that has plagued the global steel industry even before the conflict broke out.?

The impact of the Russian-Ukrainian conflict continues to spill over, superimposed on the slowdown of China's economic growth, the World Steel Association predicts that the growth of global steel demand in 2022 is expected to decrease. In addition, the continuous outbreak of the new crown pneumonia epidemic and rising interest rates in some parts of the world have also brought risks of economic downturn. The expected tightening of U.S. monetary policy will increase the risk of financial fragility facing emerging economies.

The forecast for global steel demand in 2023 is highly uncertain. The World Steel Association said the forecast is premised on the end of the Russian-Ukrainian conflict in 2022. In addition, the geopolitical pattern surrounding Ukraine will have an extremely far-reaching impact on the global steel industry, including the adjustment of the global trade pattern, the transformation of energy trade and its impact on the energy transition, and the continuous reconfiguration of the global supply chain.

We Changxing Refractory Material Co.,LTD is professional manufacturer and supplier of refractory materials for more than 30 years. Our high quality refractory products are good sold to many countries say South Africa, Bangladesh, Indonesia, Malaysia, etc. Shall any interests, welcome to contact us. Our team would make best to be your reliable partner!

Article Source:Global steel demand growth expected to be lower in 2022
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