Classification Of Refractory Materials For Intermediate Packages And Application Configuration Of Each Part

The middle package as a continuous casting process between the ladle and the crystallizer used to undertake the transition device of the steel, not only is the steel storage and distributor, or steel refining container, used to stabilize the steel flow, reduce the steel flow on the crystallizer in the billet shell of the scouring; so that the liquid steel in the middle of the package with a reasonable flow field and the appropriate length of time to ensure that the temperature of steel is uniform and the separation of non-metallic impurities floating to ensure that the cleanliness of the molten steel and the multi-furnace Continuous casting, is to improve the quality of steel and the efficiency of continuous casting of an important link, the structure is shown in Figure.

(1)Distribution of steel. For multi-flow continuous casters the steel is distributed to the individual crystallizers by means of an intermediate ladle.

(2)Stabilizing flow. Reducing the static pressure of molten steel, maintaining a stable liquid level in the intermediate ladle, and smoothly injecting molten steel into the crystallizer.

(3)Storage of steel. When replacing ladle in multi-furnace continuous pouring, the pulling speed is not reduced to create conditions for multi-furnace continuous pouring.

(4)Purification of molten steel. In the longer pouring time, so that the temperature of steel is basically unchanged, to promote further inclusions in the steel to float, to prevent the steel and air contact, to avoid oxygen absorption, nitrogen absorption.

Refractories for intermediate packages can be functionally divided into three categories:

*The first category is package lining materials, mainly composed of heat insulation layer, permanent layer and working layer;.

*The second category is the flow stabilizing parts, including slag weir, slag plate, impact plate, etc.;.

*The third category is the flow control part, which is divided into plug bar, sliding water outlet, sizing water outlet and intrusive water outlet.

For small billet continuous casting, the core of efficient continuous casting is high pulling speed, which requires that on the basis of the liquid steel quality meets the requirements, try to improve the continuous operation rate of the continuous casting machine and pouring speed, in order to realize the high out of the billet temperature and billet quality. These technical indicators, the intermediate package refractories put forward two requirements, one is high performance, the second is long life.

Good high-temperature resistance: The temperature of molten steel in the intermediate ladle is usually above 1500℃, even up to 1600℃. Therefore, the refractory materials for intermediate ladle should have good high temperature resistance performance to ensure stability and service life under high temperature conditions.

Good erosion resistance: steel contains a large number of iron oxide, calcium oxide and other impurities, these substances will produce strong erosion of refractory materials. Therefore, the refractory material for intermediate package should have good anti-erosion performance to ensure its service life.

Good thermal shock resistance: In the continuous casting process, the temperature of the molten steel in the middle ladle fluctuates greatly, which easily leads to cracks or even rupture of the refractory material. Therefore, the intermediate ladle refractories should have good thermal shock resistance to ensure its stability under temperature fluctuations.

Good air permeability: the middle pack with refractory material should have good air permeability, in order to ensure the smooth discharge of molten steel and the smooth escape of gas, so as to ensure the stability of continuous casting process.

Easy to construct and maintain: the refractory material for intermediate ladle should be easy to construct and maintain, in order to reduce the production cost and improve the production efficiency.

(1) insulation layer (10 ~ 30mm), the layer is next to the intermediate package steel shell, usually using asbestos sheet, insulation brick or lightweight castables. The best effect for the aluminum silicate fiber board, low thermal conductivity, but also easy to masonry.

(2) permanent layer (100 ~ 200mm), the layer in contact with the insulation layer, the material is generally clay brick. The whole permanent lining is the most common, the casting material is generally high alumina or mullite quality self-flowing casting material.

(3) work layer (20 ~ 50mm), the layer and steel contact, is the key part. Now it is common to use adiabatic plate or paint. Insulation plate is generally silicon, magnesium, magnesium olivine; paint for magnesium, magnesium-chromium, magnesium-calcium. Paint mechanical spraying or hand coating.

(4) seat brick, set in the middle of the bottom of the package, the installation of the middle of the package with the water outlet, the material is usually high aluminum.

(5) the bottom of the package, the material is basically comparable with the working layer, the bottom of the intermediate package of the working layer of the impact of steel is very easy to damage the parts of the package, the requirements of anti-erosion and abrasion resistance, generally with high alumina bricks or dense high alumina bricks and aluminum-chromium bricks, but also with a special large piece of high-strength magnesium tar bricks. Steel impact parts using zirconia bricks or prefabricated blocks to enhance.

(6) Covered in the middle of the package, can play a role in heat preservation and steel splash, etc., the material used in clay or high alumina castables for the package cover.

(7) slag wall (weir), the wall is built in the middle package, can be a single wall, can also be a double wall. The material of the slag-blocking wall weir, usually high alumina bricks, can also be made into prefabricated blocks, which are intended to be used for blocking. In order to improve the cleanliness of the molten steel, a molten steel filter may also be provided on the slag-blocking wall.

Magnesium-chromium bricks: Magnesium-chromium bricks are a kind of refractory material with excellent erosion resistance, which is suitable for intermediate ladle with high molten steel temperature. However, magnesium-chromium bricks have poor thermal shock resistance, are prone to cracking, and are more expensive.

High Alumina Brick: High Alumina Brick is a common refractory material with good high temperature resistance and thermal shock resistance. However, high alumina bricks have poor erosion resistance and are suitable for intermediate ladles with low molten steel temperatures.

Zircon Brick: Zircon brick is a refractory material with excellent erosion resistance and high temperature resistance, and is suitable for intermediate ladle with high molten steel temperature. However, zircon bricks are more expensive and more difficult to construct.

Silicon Carbide Brick: Silicon Carbide Brick is a refractory material with excellent erosion resistance and high temperature resistance, which is suitable for intermediate ladle with high molten steel temperature. However, silicon carbide bricks have poor thermal shock resistance and are prone to cracking.

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