硼铁精矿的碳热还原动力学

为了揭示硼铁精矿的碳热还原机理,以高纯石墨为还原剂,进行硼铁精矿含碳球团等温还原实验,并采用积分法进行动力学分析.还原温度分别设定为1000、1050、1100、1150、1200、1250和1300℃,配碳量即C/O摩尔比=1.0.当还原度为0.1<α<0.8时,温度对活化能和速率控制环节有重要影响:还原温度≤1100℃时,平均活化能为202.6 k J·mol^-1,还原反应的速率控制环节为碳的气化反应;还原温度>1100℃时,平均活化能为116.7 k J·mol^-1,为碳气化反应和Fe O还原反应共同控制.当还原度α≥0.8时(还原温度>1100℃),可能的速率控制环节为碳原子在金属铁中的扩散.碳气化反应是含碳球团还原过程中主要速率控制环节,原因在于硼铁精矿中硼元素对碳气化反应具有较强烈的化学抑制作用.     

Reduction of boron-bearing iron ore concentrate/coal composite pellet and kinetics analysis

Ludwigite is a complex iron ore containing boron and it is the most abundant boron resource in China. Boron-bearing iron ore concentrate is an intermediate product of the ore dressing process of crude low-grade ludwigite and extracting boron from it has great influence on the total boron yield. Pre-reduction of the boron-bearing iron ore concentrate is one of the important steps of the pyrometallurgical boron and iron separation process. In the present work, non-isothermal and isothermal reduction of boron-bearing iron ore concentrate/coal composite pellet was performed. The evolution of reaction fraction, carbon consumption, off-gas evolution, phase composition and microstructure were systematically revealed based on reduction experimental results in conjunction with X-ray diffraction, scanning electron microscope-energy dispersive spectrometer and electron probe micro analyzer analysis. The kinetics of the reduction of the composite pellet was also analysed. The reduction mechanism changed at a temperature around 1150°C. The rate of carbon gasification in the composite pellet during the reduction decreased mainly due to the chemical inhibition by B₂O₃ on the electron transfer.     

Structure and properties of extruded abrasive-metal composites

Powder Metallurgy and Metal Ceramics -     

Structure and properties of copper-titanium-aluminum composites produced by thermoreactive sintering

Conclusions The process of formation of composites in the Cu-Ti-Al system during thermoreaetive sintering has a diffusional character, and the resultant microstructure therefore consists of various intermetallic compounds and remains of the starting components. Varying the titanium content of these composites brings about both quantitative and qualitative changes in their structure. The most homogeneous structure is obtained in alloys with 35–45% Ti, whose end products contain the least amount of the starting components. Composites with 15–30% Ti are characterized by a comparatively high level of physicomechanical properties. These alloys can be recommended as matrix materials for the working layers of superhard abrasive tools.Translated from Poroshkovaya Metallurgiya, No. 3(255), pp. 53–56, March, 1984.     

Method of predicting the physico-mechanical properties of two-component iron–copper composites

Metallurgist - The physico-mechanical properties of an iron–copper composite are studied and a comparative analysis is made of the force and deformation parameters for making such composites...     

Structure and properties of superfine-grained iron compacted out of ultradisperse powder

The surface of the ultra-disperse iron powder particles was oxidized being in contact with the air. The powder was compacted under pressure plus torsion straining. The oxide film was found to dissolve during intensive deformation under pressure. A high degree of cold working of the resulting system FeO results in the formation of a fairly high-disperse structure during annealing. A spontaneous decay of the oversaturated solid solution at 600°C and the resulting microduplex structure comprised of the α-Fe grains sized 300 nm and FeO particles sized 200 nm leads to substantial strengthening of the alloy. The sample hardness reaches 4.7 GPa, which is higher than the hardness of original torsion strained samples.     

Structure and mechanical properties of iron sintered by electric contact heating

Translated from Poroshkovaya Metallurgiya, No. 1(337), pp. 17–22, January, 1991.     

Structure and properties of composite sintered material of the type iron-cast iron

New antifriction alloys, synthesized from mixtures of iron and cast iron powders, have been developed. A special cast iron, with interdendritic point graphite inclusions, whose initial forms and sizes remain the same after sintering while being distributed among the grains, is used to create the composite materials. Starting at sintering temperatures of 800°C a pearlitic ferrite or pearlite structure forms with initial graphite inclusions that prevent formation of structure-free cementite. A composite antifriction material with a low friction coefficient can be obtained by optimizing the process parameters and charge composition as well as the microstructure of the alloys.Scientific and Industrial Association Bakkonditsioner. Translated from Poroshkovaya Metallurgiya, No. 1 (361), pp. 60–63, January, 1993.     

含硼多元合金耐磨铸铁球的磨矿工业试验与生产实践

本文叙述五龙金矿选厂湿式磨机处理低硫化物石英脉含金矿石，采用自产含硼多元合金耐磨球，在工业试验与生产实践中均证实该球有较好的耐磨性，该球与过去使用的自产铸铁球相比，吨原矿球耗降低了１．２７ｋｇ，年可节约球耗费用４５万元，不仅企业能取得较好的经济效益经济效益。而且还有较好的社会效益。