软熔过程中烧结矿和块矿的交互作用

 为更好地明晰块矿的软熔行为并优化其在高炉内的使用,以烧结矿和澳大利亚纽曼混合块矿为研究对象,分别就两者在软熔过程中的物理和化学交互作用进行了试验研究。通过使用中子CT扫描软熔试验试样, 发现1 450 ℃时烧结矿与纽曼混合块矿的混合炉料孔隙度要高于两者单一炉料,即两者间存在着物理交互作用;通过采用扫描电镜和电子探针分析发现,1 200～1 300 ℃温度范围内烧结矿中钙和镁扩散到了块矿中,两者发生了明显的化学交互作用。在物理和化学交互共同作用下,配加约20%纽曼混合块矿的混合炉料软熔行为得到了明显改善,且其性能相似或略好于同碱度的单一烧结矿炉料,这表明块矿和烧结矿混合后能在高炉内形成温度区间更窄、位置更低、透气性更好的软熔带。

Interaction between sinter and lump during softening and melting process

The main purpose is to better understand the softening and melting (S&M) behaviour of lump in the blast furnace (BF) and how to optimise its use with sinter. As the only ferrous burden material that can be directly charged into the BF, the lump is more environmentally friendly and economically effective than sinters or pellets. Despite this, the lump utilisation in China is lower than that in other countries such as Japan. One of the main concerns is the perception that the S&M properties of individual lump samples are not as good as those of sinter or pellet. However, it has been shown that the high temperature interaction between sinter and lump can largely improve the S&M behaviour of a mixed burden composed of sinter and lump. Both the chemical and physical interaction between a basic sinter and the Newman Blend Lump (NBLL) from Australia were studied using the S&M under load test and the tablet analogue test. The physical interaction was examined using Neutron Computed Tomography scanning on the samples from interrupted S&M under load tests. The void fraction in the ferrous layer of the sinter-NBLL mixture at 1 450 ℃ was found to be higher than that for either the sinter or NBLL only burdens. The chemical interaction was studied using SEM and EPMA, which showed that the Ca and Mg diffused from the basic sinter to neighbouring lump ore particles during the S&M process in the temperature range from 1 200 to 1 300 ℃. Significant improvements were found in the S&M behaviour of a mixed burden with about 20% NBLL because of the changes in the bed structure by the physical interaction and the changes in the melt composition caused by the chemical interaction. The mixed burden performed better or at least no worse than a sinter only burden with the same total basicity. The BF modelling indicates that mixing lump with the sinter burden forms a narrower CZ with higher permeability and lower position in the blast furnace.