Some special processes are needed in the production process of nozzle brick to ensure its excellent performance and quality and meet the requirements of high temperature environment such as steel casting. The following are common special processes in the production of nozzle bricks:

I. Molding process

Isostatic pressure forming: Because of the complex shape of nozzle brick and high dimensional accuracy, isostatic pressure forming technology is widely used. In this process, the material is treated by isostatic pressing under high pressure, so that the density of the green body is more uniform and the strength is higher.

Vibration molding: The material is molded by vibration molding equipment under pressure, which is suitable for the production of complex special-shaped and large nozzle bricks.

II. Oil immersion and carbon burying process

Oil immersion process: The oil immersion process was added in the production of slide gate brick to improve its thermal shock resistance and corrosion resistance. Oil immersion technology can be divided into horizontal and vertical. The main equipment of vertical vacuum oil immersion technology includes immersion tank, storage tank, pre-cooling kiln and pre-heating kiln.

Buried carbon process: In the production of slide gate brick, a carbonized layer is formed inside the brick body by buried carbon process to enhance its corrosion resistance and high temperature stability.

III. Roasting process

Double-layer push-plate tunnel kiln firing: the double-layer push-plate tunnel kiln is used for preheating, drying and firing, the drying temperature is 200-300℃, and the firing temperature is 1300-1350℃. This kiln structure can improve the firing efficiency and ensure the uniform heating of the blank.

High-temperature sintering: sintering at high temperature makes the binder in the green body decompose and volatilize, and sintering reaction occurs between refractory aggregates to form Shuikou brick with certain strength and performance.

IV. Machining process

Finishing: The blank of Shuikou brick after leaving the kiln needs finishing, including grinding the end and adjusting the size, so as to ensure its dimensional accuracy and surface quality.

Inspection and repair: the finished Shuikou brick needs to be inspected by appearance inspection and special inspection device to ensure that there are no cracks, defects and other defects.

V. Environmental protection treatment process

Treatment of asphalt smoke: A large amount of flammable and dangerous asphalt smoke will be produced in the process of oil immersion, roasting and carbon scraping, which needs to be treated harmlessly. Treatment methods include combustion method and adsorption method.

Process water treatment: the cooling water, asphalt smoke cooling water and water seal water involved in the production process need to be recycled and purified.

The application of these special processes enables the nozzle brick to maintain stable performance in high temperature, high pressure and high corrosive environment, prolong its service life, and meet the strict requirements of refractory materials in iron and steel casting and other industries.