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高炉利用系数和燃料比取决于含铁炉料的物理和冶金性能。因此,使用实验室型篦式焙烧罐—回转窑进行了一项试验研究以确定可以同时满足物理和冶金性能标准的球团矿焙烧条件。这项试验中所采用的是密执安州恩派尔矿生产的较细粒磁铁矿精矿。计算机优选试验设计方案是根据以下6个变量:膨润土添加量(BAL)、预热时间、预热温度、焙烧时间、焙烧温度、一次冷却风量。采用一个以线性形式、二次形式和交互形式,包括了这些变量的经验特性模型,以尽量减少试验的次数。采用一种严密的统计模型方法来预测每一个经验特性模型的参数。然后,将这些模型用来确定可以同时满足所规定的物理和冶金性能标准的工艺变量操作范围。并且还研究了所规定的最高还原率(R40)和最低软熔指数(S值)同BAL的关系。最后,确定了目前恩派尔厂所能生产的球团矿的性能范围以及球团性能标准的规定值。
Blast utilization factor and fuel ratio depend on the physical and metallurgical properties of the iron-bearing charge. Therefore, a pilot study using a laboratory grate roaster - rotary kiln was conducted to determine pellet roasting conditions that meet both physical and metallurgical performance criteria. The finer-grained magnetite concentrate produced at the Empire Mine, Michigan, was used in this test. The computer preferred experimental design is based on the following six variables: Bentonite Additives (BAL), Preheat Time, Preheat Temperature, Roasting Time, Roasting Temperature, Primary Cooling Air Volume. Empirical models of these variables are included in a linear, quadratic, and interactive fashion to minimize the number of trials. A rigorous statistical modeling approach is used to predict the parameters of each empirical property model. These models are then used to determine the operating range of a process variable that meets both the specified physical and metallurgical performance criteria. The relationship between the maximum reduction rate (R40) and the lowest reflow index (S value) as determined by BAL was also studied. Finally, the performance limits of the pellets currently manufactured at the Empire plant and the pellet performance standards were established.