Study on the Physicochemical Properties of Burnt Lime for the Iron and Steel Refining.

以6种市售炼钢用石灰石为研究对象，研究了石灰石及其焙烧石灰的几种性质。另外还进行了试验，研究了焙烧石灰的水化反应性与对铁水的反应性和对熔渣的助熔性之间的关系。在水化反应性试验中，1分钟后的早期值比10分钟后的早期值与铁水反应性的关系更密切，这在炼钢实践中得到了广泛应用。即软烧石灰的水化反应活性早期值也有较大的分散，但对铁水的反应活性随着早期值的增大而增大。对于粒度较大的石灰石，尽管煅烧温度相对较低，且几乎不受煅烧条件的影响，但其水化反应活性的早期值较高。另一方面，对于粒度较小的石灰石，相对低温煅烧获得的早期值较低，通过高温煅烧或长时间保温可以改善早期值。结果表明，控制石灰水化反应活性和对铁水反应活性早期值的因素不是石灰表面的微观结构，而是宽度为1 <mu> m数量级的宏观裂纹。1 <mu> m数量级的裂缝的形成取决于石灰石的晶粒尺寸和煅烧条件（煅烧温度和保温时间），可能是由于煅烧石灰的微晶粒生长所致。水化反应性的早期值与对熔渣的助熔性之间的关系可能与对铁水的反应性一致。然而，可能需要更多的检查来明确这一点。

Several properties of limestones and their burnt limes were investigated on six commercially available limestones for the iron and steel refining. Additional experiments were carried out to study the relationships between hydration reactivity of burnt limes and reactivity to molten iron and fluxing property to molten slags.1. For the hydration reactivity test, the early value after 1 minute indicates closer relationship to the reactivity with molten iron than the value after 10 minutes which has been widely used in steelmaking practice. In other words, large scatter in early value of hydration reactivity was observed even for soft burnt lime, but the reactivity to molten iron increased with increasing of the early value.2. High early value of hydration reactivity was obtained for the limestone having large grain size in spite of relatively low temperature calcination almost independent of calcination conditions. On the other hand, low early value was obtained for the limestone having small grain size by relatively low temperature calcination, and it was improved by high temperature calcination or holding for a long time.3. It was found out that the factor controlling the early value of hydration reactivity and reactivity to molten iron was not the microstructure of burnt lime surface but macro crack of 1 <mu> m order in width.4. The formation of crack of 1 <mu> m order in width depends on the grain size of limestone and the calcination conditions (calcination temperature and holding time), and it may be attributed to micro grain growth of burnt lime by sintering.5. The relationship between the early value of hydration reactivity and fluxing property to molten slag may consist with the reactivity to molten iron. However, more examinations may be required to make it clear.