仲钨酸铵直接还原钨粉的制备工艺研究

探讨了以仲钨酸铵为原料,在氢气中直接还原制备钨粉,研究了还原温度和时间等参数对钨粉粒度和形貌的影响,分析了由该工艺所制备的钨粉其形貌特征对钨粉成形性能的影响。     

仲钨酸铵一步还原法制备钨粉的新工艺研究

以仲钨酸铵为原料,通过分段控制还原气氛,经一步还原制备钨粉。研究了仲钨酸铵粒径、还原气氛、温度、时间和装舟量等参数对钨粉粒度和形貌的影响。结果表明,最佳工艺参数为:装舟量50g、氢气流量32L/h、升温速率10℃/min、500℃保温20min、900℃保温1.5h、风冷降温到100℃,钨粉收率大于98.5%。该工艺制备的钨粉粒径可控,同时可降低生产成本。     

微米级细颗粒仲钨酸铵的制备及其工艺研究

在探明温度、溶液浓度、搅拌强度对仲钨酸铵粒度影响的基础上,研究了表面活性剂制备微米级仲钨酸铵的工艺。     

微米级细颗粒仲钨酸铵的制备及其工艺研究

在探明温度、溶液浓度,搅拌强度对仲钨酸铵粒度影响的基础上,研究了表面活性剂制备微米级仲钨酸铵的工艺。     

(NH_4)_2HPO_4-H_2O系仲钨酸铵溶解性能及磷钨杂多酸形成的影响

采用溶解平衡法研究了(NH_4)_2HPO_4-H_2O系仲钨酸铵(APT)的溶解性能。结果表明:当温度低于70℃时,仲钨酸铵的溶解度随磷酸氢二铵浓度的升高而减小;当温度达到70℃以上时,仲钨酸铵的溶解度随磷酸氢二铵浓度的升高而增大。在高温下磷钨杂多酸的形成是仲钨酸铵溶解性能和溶解速率大幅提高的主要原因。     

微米级细颗粒仲钨酸铵的制备及其工艺研究

在探明温度、溶液浓度,搅拌强度对仲钨酸铵粒度影响的基础上,研究了表面活性剂制备微米级仲钨酸铵的工艺。     

高纯钨单晶坯料预处理工艺研究

探讨了三种预处理工艺,讨论了不同工艺方法对熔炼稳定性、排除间隙杂质的作用的影响,采用高纯仲钨酸铵（APT）经还原、高温烧结、电子束熔炼预处理工艺,可有效降低间隙杂质元素含量,保证电子束悬浮区域熔炼过程的稳定性,制备出材质优良、性能稳定的高纯钨单晶产品。     

二次离子交换饱和吸附法制取超高纯仲钨酸铵工艺优化

研究了二次离子交换饱和吸附工艺制备超高纯仲钨酸铵工艺中,一次和二次交前液钨浓度、淋洗剂浓度、钨酸钠和仲钨酸铵结晶率等对除杂效果的影响。     

仲钨酸铵（APT）物性生成条件的研究

对影响仲钨酸铵结晶的粒度、粒度分布及其形貌等物性生成条件的工艺参数进行了较系统的研究,在此基础上提出了制取各粒级仲钨酸铵的工艺条件,并进行了验证试验。文中还提出了用两种不同的气体搅拌制取APT粗粒和细粒新方法的试验情况。     

钨粉制备工艺对压坯强度影响的研究

采用仲钨酸铵一步还原法,系统的研究了还原过程中还原温度、氢气流量、料层厚度、还原时间等参数对钨粉压坯强度的影响,并分析了各参数对压坯强度的影响机制。生产过程稳定易控制,实现了工业化生产。     

大方坯连铸轻压下压下过程有限元分析

基于某钢厂的铸机条件,建立了大方坯连铸轻压下的有限元模型,得到了不同压下量和固相率下铸坯表面变化量和压下辊作用范围的规律。结果表明：在一定的压下量范围内,压下后铸坯表面的反弹量约为压下量的19%;压下量每增加1mm,压下辊的作用范围增加16mm;固相率每增加0.2,反弹量增加压下量的1.7%;实施轻压下时应该考虑压下的反弹量。     

烧结矿气-固还原过程的矿物组成和显微结构变化

 利用热重分析方法研究了烧结矿与CO气体的气-固还原反应特征,重点考察了反应的不同阶段烧结矿矿物组成和显微结构的变化以及还原过程烧结矿孔隙率的变化。研究发现：由于烧结矿内矿物组成的改变,随着还原度的增加,烧结矿还原速率逐渐减缓。还原前期主要发生赤铁矿→磁铁矿和铁酸钙→磁铁矿的转变,并且赤铁矿的还原速率要高于铁酸钙。当还原度达到70%时,烧结矿内的赤铁矿、铁酸钙和磁铁矿全部被还原为浮士体和金属铁;根据还原过程烧结矿内部结构和孔隙率的变化,发现还原过程中试样的孔隙率由原来的12.43%增加至5344%,其中大部分的增加量集中在反应的前期。另外,发现存在微气孔的区域更有利于烧结矿的还原。     

连铸轻压下技术的发展和应用

介绍了轻压下技术的作用机理及发展过程，分析了轻压下工艺参数：压下区间、压下量及压下速率，研究了轻压下工艺对铸坯组织结构、性能、表面质量和内部裂纹的影响。     

钒钛磁铁矿含碳球团还原的影响因素

通过单因素实验考察了还原温度、还原时间及碳氧摩尔比(n_C/n_O)对钒钛磁铁矿含碳球团还原的影响,结合扫描电镜照片解释了钒钛磁铁矿的还原机理.实验结果表明,适当升高还原温度、延长还原时间及增加碳氧摩尔比均可以促进钒钛磁铁矿的还原,并且金属化率随还原温度的升高先急剧升高而后趋于平缓,随着还原时间的延长及碳氧摩尔比的增加而先升高后降低,而残碳量随着反应的进行不断降低.当还原温度为1350℃,还原时间为30 min,碳氧摩尔比为1.2时,球团的金属化率达到最大值.通过扫描电镜照片可以看出,球团在还原过程中形成了铁连晶,并且在不同的还原条件下铁连晶的大小及形态不同.      

Mechanisms of Swelling of Iron Ore Oxidized Pellets in High Reduction Potential Atmosphere

The influences of the time,temperature and atmosphere on the reduction swelling of oxidized pellets were investigated by single factor experiments.The mechanisms of reduction swelling of oxidized pellets were analyzed and investigated by SEM(scanning electron microscopy)and XRD(X-ray diffractometer)analysis.The results show that the change rules of reduction swelling index of oxidized pellets in different reduction atmospheres are very similar.With the increase of reduction time,the reduction swelling index moves up firstly and then down.When the reduction temperature is above 900℃,α-quartz turns intoα-tridymite,and the transition generates additional volume expansion effect.The reduction swelling index changes faster in H2 atmosphere than in CO atmosphere.Increasing H2 content in the reduction atmosphere is useful to decrease the reduction swelling index,but it is also easy to cause oxidized pellets cracking.     

连铸轻压下技术冷态模拟研究

通过自行创新设计的实验装置,应用丁二腈-5%(摩尔比)水透明模型合金冷态模拟研究方法,在压下量为0～5 mm范围内,研究连铸轻压下对中心偏析的影响.结果表明:随着压下量的增加,压下段中心偏析逐渐改善.较小的压下量对中心偏析改善作用较小;随压下量增加,压下量对中心偏析的改善作用逐渐增大;当压下量增加到一定程度时,压下量对...     

Reduction Behavior of Sinter Based on Top Gas Recycling-Oxygen Blast Furnace

 In order to explore the behavior laws of sinter reduction in TGR-OBF (top gas recycling-oxygen blast furnace), reduction experiments of sinter have been conducted by thermal balance mass loss method with different atmospheres, temperatures and volume flows. The changes of RI (reduction degree of Fe2O3), RI′ (reduction rate of Fe2O3) and r (reduction degree of FeO) have been examined. The results show that the reduction of sinter was significantly improved under TGR-OBF atmosphere, and the RI and r were measured up to 98.2% and 97.8% at 900 ℃ respectively. With increasing of the reduction temperature, the reduction of sinter speeded up greatly, and the reduction time-duration shortened from 117 min at 900 ℃ to 63 min at 1100 ℃. Moreover, the reduction of sinter enhanced with increasing of the reductive gas flow. When the flow increased from 10 to 15 L/min, the initial reduction rate of sinter increased from 2.47%/min to 3.73%/min. While increasing H2 and CO contents in the reductive atmosphere, the reduction of sinter was promoted. Besides, H2 influenced more evidently than CO to the reduction of sinter, especially in the later stage of the reduction process, for instance, the reduction of wustite will be improved enormously when increasing the H2 content in the reductive atmosphere.     

Reduction characteristics and kinetics of iron oxide by carbon in biomass

The characteristics and kinetics of iron oxide reduction by carbon in biomass composites were studied. Iron oxide can be reduced by biomass very rapidly, and the degree of metallisation and reduction increases with temperature. Iron oxide reduction by carbon in biomass can be divided into two stages: reduction by volatile carbon followed by reduction by non-volatile carbon. The reduction times of the two stages both decrease with increasing temperature. The first reduction is controlled by gas diffusion, whereas the second stage is dominated by carbon gasification.     

Effects of embedding direct reduction followed by magnetic separation on recovering titanium and iron of beach titanomagnetite concentrate

Embedding direct reduction followed by magnetic separation was conducted to fully recover iron and titanium separately from beach titanomagnetite(TTM).The influences of reduction conditions,such as molar ratio of C to Fe,reduction time,and reduction temperature,were studied.The results showed that the TTM concentrate was reduced to iron and iron-titanium oxides,depending on the reduction time,and the reduction sequence at 1 200°C was suggested as follows:Fe_(2.75)Ti_(0.25)O_4→Fe_2TiO_4→FeTiO_3→FeTi_2O_5.The reduction temperature played a considerable role in the reduction of TTM concentrates.Increasing temperature from 1 100 to 1 200°C was beneficial to recovering titanium and iron,whereas the results deteriorated as temperature increased further.The results of X-ray diffraction and scanning electron microscopy analyses showed that low temperature(≤1 100°C)was unfavorable for the gasification of reductant,resulting in insufficient reducing atmosphere in the reduction process.The molten phase was formed at high temperatures of 1 250-1 300°C,which accelerated the migration rate of metallic particles and suppressed the diffusion of reduction gas,resulting in poor reduction.The optimum conditions for reducing TTM concentrate are as follows:molar ratio of C to Fe of 1.68,reduction time of 150 min,and reduction temperature of 1 200°C.Under these conditions,direct reduction iron powder,assaying 90.28 mass%TFe and 1.73 mass% TiO_2 with iron recovery of 90.85%,and titanium concentrate,assaying 46.24mass% TiO_2 with TiO_2 recovery of 91.15%,were obtained.     

回转窑一步法直接还原铁生产的试验研究

以新疆磁铁精矿为原料,采用一步法直接还原,研究高强度、高还原性预热球团的制备及煤基直接还原的工艺.研究了实验室转鼓模拟回转窑装置中直接还原铁的生产工艺.讨论了配碳比、反应温度、反应时间等工艺参数对金属化率、脱硫率等回转窑直接还原铁的主要质量指标的影响,提出了本试验原料条件下,回转窑生产直接还原铁的最佳工艺参数.研究结果...