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，将铬矿粉注入铁水中，利用铁水中的溶解碳进行还原。在20 kg规模的试验中，首先验证了新工艺的原理。其次考察了温度、喷矿量、粉料粒度和载气流量对还原速度的影响。从化学工程的角度对实验结果进行了讨论。从还原过程中硅的行为和初始铬含量对还原速率的影响等方面，从动力学角度对还原过程进行了讨论。最后指出，为了提高还原程度，应将渣放在熔体表面，使未还原部分的矿石溶解并进一步还原。为弄清铬铁矿在熔渣中的溶解还原行为，进行了小型试验。Prefe…结果表明，铬铁矿、石墨粉和炉渣的混合物加热到较高温度时，铁氧化物的还原速度较快，实验条件的影响较大。考察了铁水中溶解碳对铬渣的还原速率，并对其反应机理进行了探讨。测定了氧化铬在炉渣中的溶解度。结果表明，在炉渣中加入石墨粉后，炉渣的溶解度显著增加。最后，对铬铁矿进行了预还原烧结试验。揭示了氧化铬还原的起始温度和最佳烧结升温方式，并在5t中试转炉上进行了铬铁矿熔融还原试验。结果表明，即使在&lt；O2&gt；同时燃烧碳质物质的条件下，熔融还原也能有效地进行。获得了底吹矿粉的还原速度，并与20 kg规模试验结果进行了比较。结果表明，喷吹~lt；O_2&gt；矿粉并在风口上方火点熔融，还原程度明显提高。然而，一个重要的技术问题出现了，即粉料输送系统的管路受到磨矿粉的严重侵蚀。为了克服这一问题，开发了一种新的顶喷方法，即矿粉通过煤粉和氧气的燃烧框架。较少

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