Plug bricks, nozzle bricks and sleeve bricks are commonly used refractories in iron and steel smelting and continuous casting, and they play an important role in the gating system. The following are the applications of these three refractories:

I. Plug bricks

Plug brick is the core component of plug rod system, which is used to control the flow of molten steel. It is composed of refractory body and built-in steel argon blowing rod core, and the opening and closing of molten steel and flow regulation are realized through the cooperation with nozzle brick. Plug bricks are usually made of pyrophyllite, graphite, high-purity carbon powder and other raw materials, with resin as binder, through impregnation and dry distillation. In the pouring process, the plug brick needs to withstand the erosion and erosion of high-temperature molten steel, so it is required to have high fire resistance, corrosion resistance and good thermal shock stability. The material of plug brick is generally clay, high alumina or tar impregnated unfired high alumina. For high temperature steel and special steel, zircon or alkaline material will also be used.

II. Shuikou Brick

The nozzle brick is a refractory steel water outlet embedded in the brick at the bottom of the ladle, which is used to control the outflow of molten steel. Its upper opening is arc-shaped, which is convenient to open and close the nozzle and reduce the resistance of molten steel flow; The lower section is a straight section to stabilize the injection flow. The inner diameter of nozzle brick directly affects the pouring speed, and its material selection depends on the volume of steel bucket, pouring method and steel grade. Common materials include clay, high alumina, magnesium, magnesium chrome and zirconium. In continuous casting technology, submerged nozzle brick is widely used between tundish and crystallizer to prevent secondary oxidation, nitriding and splashing of molten steel, and at the same time adjust the flow state and injection speed of molten steel.

III. Sleeve bricks

Sleeve brick is a hollow refractory brick pipe which is sleeved outside the plug core rod, and is used to protect the metal core rod from the direct action of high temperature metal and slag. It is connected by the female and male interfaces at both ends to keep the rigidity of the stopper to control the injection flow. The material of sleeve brick is generally clay or high aluminum, which has high thermal stability and slag resistance. Its size design should meet the requirements of service life and tapping time, and at the same time take into account the manufacturing cost. Sleeve bricks are widely used in electric furnace covers, blast furnaces, hot blast stove partitions, ladle linings, steel drums, hot metal cars, cement kilns, glass kilns and other thermal furnace linings.

To sum up, plug brick, nozzle brick and sleeve brick are indispensable in iron and steel smelting and continuous casting. They meet the requirements of molten steel control and protection in high temperature environment through different structure and material design.