升温速率与预熔过程对含氟渣熔点影响分析

 为探究升温速率以及预熔处理等条件对CaF₂基渣系的熔点影响,揭示高温下含氟渣的挥发特性,采用半球点熔点检测与热重分析联合试验。结果表明,在熔点测定过程中,含氟渣的失重率为5%~17%,且随升温速率的减小而增大。预熔前后对无氟渣的熔点测定值几乎无影响,而对含氟渣,混合型与预熔型炉渣熔点差值近70 ℃,造成熔点差异的原因并非物相组成的改变,而是混合型渣样存在明显挥发,达到熔点时失重率为8.3%,而重熔渣失重率仅为2%。混合型渣样中存在大量的自由CaF₂,且熔化初期比表面积较大,导致挥发率较大,而重熔型渣样中CaF₂多以氟铝酸钙以及枪晶石等形式存在,结构致密,挥发受到抑制。这为探究挥发对含氟渣系的熔点等高温性能的影响提供理论基础。

Effect of heating rate and pre-melting process on melting point of fluorine-containing slag

In order to explore the effect of heating rate and pre-melting on melting point and reveal the volatility characteristics of fluorine-containing slag at high temperature,a combined experiment of hemispherical melting point detection and thermogravimetry(TG)was taken. The melting point and volatilization characteristics of the fluorine-containing slag system were investigated under different heating rates and pre-melting processes. The results showed that the weight loss rate of fluorine-containing slag was 5%-17% during the melting point determination and it increased with the heating rate decreasing. There was almost no influence on the melting point of the fluorine-free slag before and after pre-melting,and for the fluorine-containing slag,the difference between the melting point of the mixed and the pre-melted slag was nearly 70 ℃. The reason for the difference was not the change of the phase composition,but the mixed slag had obvious volatilization. When is reached,the weight loss of the mixed slag was 8.3% at the melting point and that of the pre-melted slag was only 2%. There was a large amount of free CaF₂ in the mixed slag sample,and for the pre-melted slag,CaF₂ was mostly in the form of calcium fluoroaluminate and cuspidine. It provided a theoretical basis for exploring the effect of volatilization on high-temperature properties such as the melting point of fluorine-containing slag.