Nitrogen Silicon Carbide Furnace Eye Bricks for Submerged Arc Furnaces

Ferroalloy ore furnace linings are basically carbonaceous linings. Carbonaceous furnace lining has very obvious advantages, but carbonaceous materials have obvious shortcomings in practical applications such as tap holes. After continuous exploration and application, Nitrogen Silicon Carbide Bricks were finally selected as the taphole material. At the same time, it has continuously changed its masonry methods and operating procedures for the use of furnace eyes and has achieved certain success.

Ferroalloy Ore Submerged Furnace Lining

Nitrogen Silicon Carbide brick manufacturing process principle and advantages and disadvantages

Nitrogen Silicon Carbide bricks use silicon carbide (SiC) as aggregate, add industrial silicon powder, stir evenly, and stamp into shape. The thickness should be moderate and not too thick. If it is too thick, the nitrogen permeability will be low and the performance of the product will be reduced. It is nitrided and sintered at high temperature, 3Si+2N2=Si3N4. This reaction generates fibrous Si3N4, which tightly combines SiC particles to form a two-dimensional spatial grid structure and obtain high strength. At the same time, N2 replaces the oxygen in the particles and obtains strong antioxidant properties. This product contains 70%~75% silicon carbide and 18%~25% silicon nitride.

The advantages of this material are high strength at high temperatures, good thermal shock resistance, and alkali corrosion resistance. Low thermal expansion rate, good oxidation resistance, resistance to metal and slag erosion, corrosion resistance and gas erosion. The disadvantage is that the antioxidant effect of Si3N4 decreases under the action of steam. Water vapor will decompose Si3N4 above 800℃, and exposure to air at high temperatures will shorten its service life. In addition, due to its structure and nitriding effect, the thickness of Nitrogen Silicon Carbide bricks is also limited. Currently, the company uses Nitrogen Silicon Carbide bricks with a thickness of 150mm, and the furnace eye bricks are made of 5 high-pressure bonded bricks. During daily use, it is found that the phenomenon of fragmentation will occur in areas with obvious temperature differences.

Nitrogen Silicon Carbide Bricks

Nitrogen Silicon Carbide furnace eye brick construction method

The company began to introduce manganese-silicon alloy electric furnaces built with Nitrogen Silicon Carbide bricks in 2011 and subsequently introduced them to other furnaces. During the practice, a set of masonry methods suitable for combining silicon nitride carbide furnace eye bricks with ordinary carbon bricks has been explored, and certain results have been achieved.

Improved masonry method of Nitrogen Silicon Carbide bricks

Improve the masonry method according to the use and wear of the previous masonry method. The masonry mainly uses silicon nitride carbide composite furnace eye bricks to replace the original two 600mm carbon bricks.

To avoid the weak links in the first masonry construction, special-shaped Nitrogen Silicon Carbide bricks are used around the furnace eye to replace the original ordinary masonry bricks. Nitrogen Silicon Carbide composite bricks are used instead of the original ordinary carbon bricks, and the joints are extended to the vicinity of the "furnace dead material area". It avoids slag iron erosion and molten iron erosion caused by differences in joint expansion coefficients.

Usage process tracking and loss status

The company's 402# and 403# furnaces are all built in this way, among which the 402# and 403# furnaces are in use to this day (the furnace shutdown time was about 15 months). At present, the furnace eye is in good use, and only the joints above the furnace eye occasionally overflow with slag iron. During this period, according to the slagging conditions of the furnace holes, the furnace holes are heat-sealed (6 furnaces/day for 402# and 403# furnaces, and later reduced to 3 furnaces/day).

This masonry method can extend the weak link between Nitrogen Silicon Carbide bricks and ordinary carbon bricks to the dead material area of the furnace, effectively avoiding the erosion of high-temperature slag iron on the paste-filled joints. The loss inside the furnace eye is smaller and the use effect is better. At the same time, Nitrogen Silicon Carbide bricks are inlaid on the entire carbon brick, and the carbon bricks at the bottom of the furnace eye extend out of the furnace shell. It ensures the sealing effect of the taphole and effectively avoids oxidation corrosion on the outside of the taphole.

To purchase high-quality silicon carbide bricks, please contact us at sales@rongshengrefractory.com. We provide high-quality products and perfect customer service.