Development of VOD ladle lining refractories

Magnesia-chrome brick was first used in VOD ladle lining because of its excellent slag resistance. However, under intermittent operation of VOD ladle, magnesia-Chrome brick is easy to produce spalling damage and poor thermal shock resistance. Because of the environmental protection of hexavalent chromium, the use of chromium-containing refractories is more and more restricted. At present, domestic stainless steel steel mills have rarely used magnesia-chrome brick.

In Europe, VOD ladle lining is mostly made of (magnesium) dolomite bricks. Compared with magnesia-Chrome brick, dolomite brick has good thermal shock resistance due to its high temperature flexibility. Most VOD ladles in China use magnesium-calcium bricks fired at high temperature. Although magnesium-calcium brick has the function of purifying molten steel and has better thermal shock resistance than magnesium-chromium brick, the content of CaO in the brick reduces slag erosion resistance under the condition that the slag composition of VOD ladle varies greatly and is mainly acidic slag. Due to the hydration problem, magnesium-calcium brick is not suitable for intermittent production, and the management of storage, use and other aspects puts forward very high requirements.

In the smelting of low carbon and ultra-low carbon stainless steel, stainless steel plants are reluctant to use magnesium carbon brick for fear that the liquid steel may be carburized by using magnesium carbon bricks in VOD ladle. In fact, these problems can be minimized by using low-carbon magnesium-carbon bricks. Although low carbonization tends to reduce the thermal shock resistance, the bricks with excellent thermal shock resistance can be developed by selecting the best amount of special asphalt and antioxidant.

Magnesium Carbon Brick