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The reducibilty of chromite ore and reactivity of carbonaceous reductants.

机译：亚铬铁矿的还原性和含碳还原剂的反应性。

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The purpose of this dissertation is to study the reducibility of chromite ore and reactivity of carbonaceous reductants. The effect of temperature, particle size, composition, reducing agent and reducing atmosphere on the kinetics of the reduction of given chromite (obtained from Xstrata) was studied.using tga,and to test reactivity of the reductant, present experimental data was applied to Arrhenius model.udThe ore is reduced by reductants namely coke, coal, charcoal and graphite at temperatures between 1000 ºC and 1300 ºC under argon atmosphere. Particle size range of as received, (+50μm-100μm), (+100μm-150 μm), (+150μm–200 μm) were used. For each experiment a calculated mixture of chromite and reductant was mixed with acetone and the mixture was reduced using a TGA furnace.The results indicated that the reduction rate was a function of temperature and particle size.The reduction at 1000 ºC under argon atmosphere is minimal.As temperature is increased to 1100 ºC, 1200 ºC and 1300 ºC it was observed that reduction rate of this chromite increased and sample having finer particle size fraction showed higher reduction rate at all temperature.udThe effect of the type of reducing agent namely coal, coke, charcoal and graphite was variable.At lower temperatures: 1000ºC and 1100ºC coke, coal, charcoal and graphite was order of reduction from highest reduction to lowest whereas at higher temperatures: 1200 ºC and 1300ºC order was coal, coke, charcoal and graphite.The phases formed at the end of each reduction stage were studied using SEM and optical microscope which helped to confirm the experimental data.udTo test reactivity of the reductant, present experimental data was applied to various models.A model which was found to be suitable was the Arrhenius model.The value of the activation energies obtained from fitting the data into the Arrhenius equation was used to determine the relative reactivity of the reductants, the values of the chemical reaction rate constants and effective diffusion constants were used to determine the relative speed at which the reductants can reduce the chromite ore.udThe TGA test suggest that coke has the highest reactivity since its activation energies are lowest and require less energy to induce the reductants reaction The tests also suggest that the rate controlling mechanism is diffusion of species to the reactive site since the effective diffusionudcoefficients were of the order 10-11, which were far less then the chemical rate constant of the order 10-6 to 10-5.Test also suggest that coal is fastest to react since its De values are high
机译：本文的目的是研究铬铁矿的还原性和碳质还原剂的反应性。研究了温度，粒径，组成，还原剂和还原气氛对给定亚铬铁矿还原的动力学的影响（从Xstrata获得）。使用tga，并测试还原剂的反应性，将当前实验数据应用于Arrhenius ud在氩气气氛下，在1000ºC至1300ºC之间的温度下，通过还原剂（即焦炭，煤炭，木炭和石墨）还原矿石。使用的粒径范围为（+50μm-100μm），（+100μm-150μm），（+150μm-200μm）。对于每个实验，将计算出的亚铬酸盐和还原剂的混合物与丙酮混合，并使用TGA炉将其还原。结果表明，还原速率是温度和粒径的函数。在氩气氛下1000ºC时的还原最小当温度升高到1100ºC，1200ºC和1300ºC时，观察到该亚铬酸盐的还原率增加，且粒度分数较小的样品在所有温度下均显示出较高的还原率。 ud还原剂类型即煤的影响，焦炭，木炭和石墨是可变的。在较低温度下：1000ºC和1100ºC，煤，木炭和石墨的还原顺序是从最高还原到最低，而在较高温度下：1200ºC和1300ºC的顺序是煤，焦炭，木炭和石墨用SEM和光学显微镜研究了在每个还原阶段结束时形成的相，这有助于确认实验数据。对于还原剂，将目前的实验数据应用于各种模型。一个合适的模型是Arrhenius模型。将数据拟合到Arrhenius方程中获得的活化能值用于确定还原剂的相对反应性。还原剂，化学反应速率常数和有效扩散常数的值用于确定还原剂还原铬铁矿的相对速度。 udTGA测试表明，焦炭具有最高的反应活性，因为其活化能最低且需要诱导还原剂反应所需的能量更少。测试还表明速率控制机制是物质扩散到反应位点，因为有效的扩散系数/ udcoefficients约为10-11，远小于该数量级的化学速率常数10-6至10-5。试验还表明，煤的De值高，因此反应最快

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    Bhalla Amit;

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  • 年度 2013
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