Developmental Scientific Research on Smelting Reduction of Pulverized Chromite Ores by The Injection into Molten Iron.

对铬铁矿熔融还原生产铁铬合金进行了开发性科学研究，将粉碎的铬铁矿喷入铁水中，利用铁水中的溶解碳进行还原。考察了温度、喷矿速度、粉末粒度和载气流量对还原率的影响。从化工角度对结果进行了讨论。从还原过程中Si的行为以及初始Cr含量对还原速率的影响，从动力学角度对该过程进行了讨论。最后指出，为了提高还原度，应将熔渣置于熔体表面，使未还原部分的矿石溶解并在熔体表面进一步还原，并进行了小型实验，以阐明铬铁矿在熔渣中的溶解和还原行为。普雷费 关于我们 研究了铬铁矿、石墨粉和炉渣混合物在高温下的还原反应及实验条件的影响。研究了铁液中溶解碳对含铬渣的还原速率，并对反应机理进行了探讨。测定了氧化铬在渣中的溶解度。结果表明，在渣中加入石墨粉后，溶解度急剧增加。最后，对铬铁矿进行了预还原烧结试验。确定了氧化铬还原的起始温度和烧结的最佳加热方式，并在5t转炉上进行了铬铁矿熔融还原试验。结果表明，即使在同时燃烧含碳物质的条件下，熔融还原也能有效地进行<O_2>。获得了底喷矿粉的还原率，并与20 kg规模试验结果进行了比较。结果表明，在炉口正上方的火点处喷入矿粉并使其熔融，可显著提高还原度<O_2>。然而，一个重要的技术问题出现了，粉料输送系统的管道被磨料矿粉严重侵蚀。为了解决这一问题，开发了一种新的顶喷法，即在煤粉和氧气的燃烧框架中加入矿粉。少

Developmental scientific research on the smelting reduction of chromite ores has been carried out to produce Fe-Cr alloy, in which pulverized chromite ore was injected into molten iron and was reduced by the dissolved carbon in it.In 20 kg scale experiments, at first, the principle of the new process was verified. The effect of temperature, ore injection rate, powder size and flow rate of carrier gas on the reduction rate was examined secondly. The results were discussed from chemical engineering view point. From the behavior of Si during the reduction process and the effect of initial Cr content on the reduction rate, the process was discussed from kinetic view point. Finally, it was revealed that the slag should be put on the melt surface to dissolve the un-reduced part of ores and reduce further there, in order to improme the reduction degree.Small scale experiments have been carried out, in order to clarify the dissolution and reduction behavior of chromite ore into the slag. Prefe … More rential reduction of iron oxides and the effect of experimental conditions were revealed, when the mixture of chromite ore, graphite powder and slag was heated up to high temperature. The reduction rate of chromite bearing slag by the dissolved carbon in iron melt was examined and the reaction mechanism was discussed. The solubility of chromium oxide in the slag was determined. It was found that the solubility increase drastically when graphite powder was added to the slag. Finally, the experiment on pre-reduction and sintering of chromite ore has been carried out. The initiation temperature for the reduction of chromium oxide and the optimum heating pattern of sintering were revealed.The smelting reduction of chromite ore has been also examined in 5 t test converter. It was revealed that the smelting reduction could proceed effectively even in the condition where the combustion of carboneceous materials by <O_2> proceeded simultaneously. The reduction rate of bottom-injected ore powder was obtained and was compared with that obtained in 20 kg scale experiments. It was found that the reduction degree was improved markedly when the ore powder was injected with <O_2> and fused at the fire spot just above the tuyere. However, an important technological problem arose, that tubings of powder conveying system was seriously attacked by the abrasive ore powders. In order to overcome the problem, a new top injection method was developed, in which the ore powder should pass through the combustion frame of pulverized coal and oxygen. Less