Ceramsite sand AFS20-30 for ladle well filler material
In the steel metallurgical industry, well filler compound is an important component of steel casting ladles. Most nozzle filer are made of silica sand and chromite sand as the main raw materials. In recent years, on the one hand, the price of chromium ore sand has continued to rise. On the other hand, the requirements for chromium residue for special chromium-free steel have become more stringent. Ceramsite sand AFS20-30 has become a substitute for ladle drainage sand raw material.
Ceramsite sand AFS20-30 can meet the requirements of filler compound performance by adding 100%, 50% or 30% to improve the opening rate.
As a raw material for ladle well filler, ceramic sand AFS20-30(Ceramic sand AFS20/30) has the following advantages:
1. High refractoriness and strong thermal shock resistance
Ceramsite sand AFS20/30 is a kind of electrofused bauxite beads at high-temperature. The main component is Al₂O₃ (≥70%). The refractoriness can reach above 1800℃. Therefore, it can withstand the high temperature impact of molten steel and the erosion of impurities in molten steel.
2. Low thermal expansion coefficient and high mechanical strength.
Ceramic beads has a low expansion coefficient (about 0.13% at 1000℃) and high compressive strength of particles. It is not easy to crack under rapid cooling and heating conditions. Moreover, it will not cause clogging of the ladle nozzle due to volume expansion at high temperature, affecting the pouring rate.
3. Excellent fluidity
Spherical particles (roundness ≥ 90%) have a smooth surface, high bulk density, low porosity (about 30%). It gains better fluidity than quartz sand or chromite sand. Therefore, although the specific gravity of ceramsite sand is lower than that of chromite sand, it can still achieve the purpose of rapid sinking after pouring with its excellent fluidity, thereby improving the pouring rate of ladle casting.
4. Environmental protection and safety
The main components of ceramic sand are alumina and a small amount of silicon. It does not contain hexavalent chromium and other elements. It can effectively avoid the presence of chromium residues in the metal and affect the quality of steel. However, chromite sand will release Cr6+ at high temperatures. That has an adverse effect on steel that does not contain chromium.
5. Stability of price and quality
The raw material of ceramic sand is bauxite. It is artificial sand made by electric melting process. The price fluctuation of bauxite is not as drastically affected by the international market of chrome ore. In addition, chromite sand is a natural sand, while ceramic sand is artificial sand. The particle size distribution of ceramsite sand is mainly controlled by the production process. So it can meet customer’s customized requirements and ensure a small batch difference.
It can be seen that ceramic sand can partially replace chromite sand as the raw material of ladle nozzle filler compound with its spherical structure, excellent fluidity, heat resistance, chemical inertness and cost stability.
