2017年6月28日星期三

Development of continues casting & tundish

Refractory Castable
Refractory Castable
CCM first appear in 1950s, it is characterized by fast casting and focus investment. CCM technology was developing in a very fast speed. In Year 1970, CCM only took 5.6% all over the world, refractory brick while the data reached 62.4% in Year 1990, and in some developed countries, it was even 95%. In recent years, many steel plants adapted CCM instead of mould casting. Until Year 1994, in total 24 countries are of full CCM now.

Compared with traditional mould refractory castable casting, CCM can improve metal recycle rate and low down power consumption. CCM can make the melting work simple and short the melting time, in which way the production efficiency can improve in a large degree. Tundish is a middle progress of steel making, and it is the kep point which can decide continues casting or not. Furthermore, tundish would have a big effect on melten refractory material steel quantity and quality. Its functions are as following:

1. Diversion. For multi-strand CCM machine, the melten steel would be divided from tundish.

2. Continues casting. When refractory firebrick multi-furnace continuous casting, tundish can be a holder when changing ladle.

3. Lowing down presure.

4. Protecting melten steel quality. Through using covering agent, long nozzle and other protecting device, tundish can help to protect the melten steel quality.

Article source:
Development of continues casting & tundish

E-mail:sales8@chinaelong.com

2017年6月19日星期一

Basic properties of refractory material for steel making

As we all know that China refractory is of various kinds and is widely used and also of great importance in steel industry. The following are some refractories commonly used in steel industry summarized by Changxing Refractory engineers.

(1) Refractories for converter
Magnesia carbon refractory brickis used for furnace cap, tapping converter mouth, before and after the surface, weld pool and bottom; high strength magnesia carbon brick is used for trunnion and slag line. Usually the MgO content in magnesia carbon brick is 70 ~ 75%, graphite is 16 ~ 20%, bulk density is 2.8 ~ 2.9 g/cm3, compressive strength is 25 ~ 30 MPa. The elements of high strength magnesia carbon brick are the same elements as magnesia carbon fire brick, but its compressive strength should be 30 ~ 42 MPa.

(2) Refractories for electric furnace
Furnace hearth, furnace slope and molten pool are overall rammed with magnesia clinker, or constructed with magnesia brick which is made of magnesia carbon brick and tar asphalt; high-quality MgO-C bricks is used for hot and slag line area; magnesia brick and magnetite chrome brick are used for tapping hole and the two sides of furnace door; high alumina bricks or high alumina brick clay brick are used for furnace cover.

(3) Refractories for UHP EAF
For permanent lining of ultra high power EAF, using magnesium stone; for furnace doorjamb, using magnesia chrome brick; for slag line, eccentric bottom and molten pool, using magnesia refractory firebrick; for hot spots, furnace wall and tapping hole, using magnesite carbon brick; for furnace cover, using high alumina brick; for tapping hole filler, using high ankerite filling material.

According to the working conditions of various steel furnaces, it can be proved that the refractory materials for furnace working circumstance is very bad. Therefore, whatever refractory for smelting are used, it must possess the following properties.
(1) High temperature resistant and high refractoriness.
(2) Erosion and erosion resistance to high temperature molten steel and slag.
(3) The steelmaking furnace works discontinuously, thus requires refractory material with good thermal shock resistance and spalling resistance.
(4) High mechanical strength, can withstand impact of furnace tilting and furnace charge loading with no damage.

Article source:
Basic properties of refractory material for steel making
E-mail:sales8@chinaelong.com

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