Production Process of High Thermal Conductivity Graphite Bricks

High thermal conductivity graphite bricks used for blast furnace bosh to furnace body are well used in blast furnaces due to their outstanding features such as good thermal conductivity and high temperature strength, low porosity and ash content, and excellent alkali resistance. They meet the use requirements of blast furnaces. In the production process of high thermal conductivity graphite bricks, the process route is determined and controlled as follows.

Production Process of Graphite Bricks

Using appropriate formulas, according to the requirements of physical and chemical indicators of finished products, combined with the actual production of artificial graphite, the following process route is determined: coke-calcination-crushing (grinding)-batch-mixing (adding binder asphalt)-extrusion molding-roasting-primary impregnation-secondary roasting-secondary impregnation-third roasting-graphitization-processing.

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Process Control

(1) Control of calcination quality:

According to the Arrhenius formula, that is, 1nK=A-Q/T, K is the reaction rate constant, A is a constant, Q is the binding energy, and T is the temperature. If the defects of the product increase, the binding energy will decrease, which will lead to an increase in the K value, that is, the reaction rate will be accelerated and the consumption will be accelerated.

Based on this, the temperature of the 5th to 8th calcination zone of the 8-layer countercurrent pouring calcining furnace is controlled at 1250~1300℃. And the discharge speed is appropriately adjusted to keep the true density of the calcined coke at about 2.07g/cm3. At this time, the active points of the calcined coke are moderate, the adsorption is stable, the amount of asphalt consumed in the molding process is small, the product strength is high, and the performance is good.

If the calcination temperature is too low, the calcined coke will shrink twice in volume during the subsequent graphitization heat treatment, crack defects will occur in the structure, and the product consumption will be accelerated during use. If the calcination temperature is controlled too high, the active points of the calcined coke will increase and the adsorption will be enhanced. A large amount of binder is used. During the later roasting heat treatment, the light fraction of asphalt is removed, which increases the porosity and defects of the product and accelerates the consumption of the product during use.

(2) Extend the kneading time and improve the kneading temperature control.

In recent years, with the deep processing of coal tar products, the properties of coal tar have changed, the softening point has increased, the viscosity of the asphalt is relatively large, and the plastic range has decreased. Through the analysis of the asphalt viscosity-temperature curve, it is determined to increase the asphalt impregnation temperature and kneading temperature to increase the asphalt impregnation effect on coke, ensure that the kneading power curve is not deformed, make the paste have good plasticity, and ensure the structure of the graphite brick.

At the same time, adopt a high-temperature feeding system to reduce the plasticity difference of each row of paste; reduce the tamping pressure and reduce the internal structure. Extend the pre-pressing time of the press to increase the density of the product.

(3) Multiple impregnation process:

In order to ensure a low apparent porosity of the product and ensure the comprehensive performance indicators of the product, the product is added with two impregnations to fill the pores and reinforce the product. The product must be thoroughly cleaned after roasting and before impregnation. The product requires staggered loading in the basket to ensure the gap and impregnation. The high-pressure impregnation pressure is ≥1.5MPa and the vacuum degree is ≥0.09MPa.

(4) The graphitization adopts a small furnace core, a power transformer of 16000KVA, a current density of 2.5A/cm2, and a graphitization temperature of 2900~3000℃ or above. The higher the graphitization heat treatment temperature, the higher the starting temperature of the graphite material oxidation, and the stronger the material's oxidation resistance.

(5) Due to the different shapes of the finished products, high processing precision requirements and large quantities.

The processing technology adopts the route of sawing first, then planing, and finally milling. The width and height tolerance of the graphite bricks are controlled within ±0.5mm on the secondary precision platform.

The application of high thermal conductivity graphite bricks in blast furnaces, high thermal conductivity graphite bricks used for blast furnace bosh to furnace body. To buy high-quality graphite bricks, please choose Rongsheng Refractory Manufacturer. Contact Rongsheng for free samples and quotations.