尼日利亚某高磷铁矿石工艺矿物学研究

利用化学多元素分析、化学物相分析、X射线衍射、扫描电镜和电子能谱等综合手段,研究了尼日利亚某铁矿石的化学组成、矿物组成、结构构造特点、嵌布特征及磷的赋存状态。结果表明:矿石以鲕状构造为主,有用矿物为赤铁矿和褐铁矿,脉石矿物很少且难以确定。铁矿物嵌布粒度细,且与脉石矿物共生紧密,不易充分解离,将给分选带来困难。矿石中有害元素磷的独立矿物较少,杂质磷主要以类质同象和极细的机械混入物的形式存在于铁矿中。该矿石属于高磷难选铁矿石。     

还原剂种类对高磷鲕状赤铁矿直接还原提铁降磷的影响

以褐煤、烟煤、无烟煤、焦炭为还原剂, 使用直接还原-磨矿-磁选的方法, 对高磷鲕状赤铁矿煤基直接还原提铁降磷过程进行了详细研究。结果表明: 不同温度条件下, 不同还原剂对还原铁的铁品位、铁回收率和磷品位影响趋势相同。在1 150 ℃时, 焦炭对直接还原提铁降磷并没有明显优势, 调节不同煤或者焦炭的用量都可以达到铁品位90%以上, 磷品位0.1%以下, 铁回收率80%以上的指标; 另外煤的变质程度越高, 所需煤用量越少。     

某微细嵌布贫赤铁矿石直接还原-弱磁选试验

湖南某赤铁矿石铁品位约27%,大部分铁矿物嵌布粒度在5 μm左右。对该矿石进行煤基直接还原-弱磁选试验研究,主要考察了还原温度、还原时间对还原效果的影响以及磨矿细度、磁场强度对弱磁选效果的影响。试验结果表明：将原矿压团后与烟煤（煤与矿的质量比为2∶1）在1 150 ℃下还原焙烧100 min,所得还原矿的金属化率为93.41%;还原矿磨至-0.043 mm占90.22%后在63.68 kA/m的磁场强度下经1次弱磁选,可获得铁品位为75.71%、金属化率为92.11%、铁回收率为91.12%的铁精矿。     

高磷鲕状赤铁矿深度还原过程中磷的迁移规律

 针对鄂西某地高磷鲕状赤铁矿进行了深度还原技术研究,考查了还原温度、还原时间、配碳系数和CaO添加量对磷迁移规律的影响。结果表明：进入铁粉中磷的品位和回收率随着还原温度的升高和还原时间的延长而升高,随着配碳系数的增大先升高后降低,并在配碳系数为2.0时达到最大;而受CaO添加量的影响较小。还原物料的XRD和SEM分析表明大部分磷被还原为单质迁移进入了铁粉中。对高磷鲕状赤铁矿深度还原过程中磷的迁移规律进行了初步探索,为进一步研究高磷鲕状赤铁矿提供了一定的理论基础。     

FLOTATION MECHANISM OF FLUORITE AND HEMATITE WITH SODIUM NAPHTHENE SULFONATE

ＦＬＯＴＡＴＩＯＮＭＥＣＨＡＮＩＳＭＯＦＦＬＵＯＲＩＴＥＡＮＤＨＥＭＡＴＩＴＥＷＩＴＨＳＯＤＩＵＭＮＡＰＨＴＨＥＮＥＳＵＬＦＯＮＡＴＥ￥Ｇｅ，Ｙｉｎｇｙｏｎｇ；Ｑｕｅ，Ｘｕａｎｌａｎ（ＣｈａｎｇｓｈａＲｅｓｅａｒｃｈＩｎｓｔｉｔｕｔｅｏｆＭｉｎｉｎｇ...     

Achieving Insertion‐Like Capacity at Ultrahigh Rate via Tunable Surface Pseudocapacitance

The insertion/deinsertion mechanism enables plenty of charge‐storage sites in the bulk phase to be accessible to intercalated ions, giving rise to at least one more order of magnitude higher energy density than the adsorption/desorption mechanism. However, the sluggish ion diffusion in the bulk phase leads to several orders of magnitude slower charge‐transport kinetics. An ideal energy‐storage device should possess high power density and large energy density simultaneously. Herein, surface‐modified Fe₂O₃ quantum dots anchored on graphene nanosheets are developed and exhibit greatly enhanced pseudocapacitance via fast dual‐ion‐involved redox reactions with both large specific capacity and fast charge/discharge capability. By using an aqueous Na₂SO₃ electrolyte, the oxygen‐vacancy‐tuned Fe₂O₃ surface greatly enhances the absorption of SO₃^2? anions that majorly increase the surface pseudocapacitance. Significantly, the Fe₂O₃‐based electrode delivers a high specific capacity of 749 C g^?1 at 5 mV s^?1 and retains 290 C g^?1 at an ultrahigh scan rate of 3.2 V s^?1. With a novel dual‐electrolyte design, a 2 V Fe₂O₃/Na₂SO₃//MnO₂/Na₂SO₄ asymmetric supercapacitor is constructed, delivering a high energy density of 75 W h kg^?1 at a power density of 3125 W kg^?1.     

Film Flip and Transfer Process to Enhance Light Harvesting in Ultrathin Absorber Films on Specular Back‐Reflectors

Optical interference is used to enhance light–matter interaction and harvest broadband light in ultrathin semiconductor absorber films on specular back‐reflectors. However, the high‐temperature processing in oxygen atmosphere required for oxide absorbers often degrades metallic back‐reflectors and their specular reflectance. In order to overcome this problem, a newly developed film flip and transfer process is presented that enables high‐temperature processing without degradation of the metallic back‐reflector and without the need of passivation interlayers. The film flip and transfer process improves the performance of photoanodes for photoelectrochemical water splitting comprising ultrathin (<20 nm) hematite (α‐Fe₂O₃) films on silver–gold alloy (90 at% Ag–10 at% Au) back‐reflectors. Specular back‐reflectors are obtained with high reflectance below hematite films, which is necessary for maximizing the productive light absorption in the hematite film and minimizing nonproductive absorption in the back‐reflector. Furthermore, the film flip and transfer process opens up a new route to attach thin film stacks onto a wide range of substrates including flexible or temperature sensitive materials.     

Dual Effects of Nanostructuring and Oxygen Vacancy on Photoelectrochemical Water Oxidation Activity of Superstructured and Defective Hematite Nanorods

An Ar atmospheric treatment is rationally used to etch and activate hematite nanoflakes (NFs) as photoanodes toward enhanced photoelectrochemical water oxidation. The formation of a highly ordered hematite nanorods (NRs) array containing a high density of oxygen vacancy is successfully prepared through in situ reduction of NFs in Ar atmosphere. Furthermore, a hematite (104) plane and an iron suboxide layer at the absorber/back‐contact interface are formed. The material defects produced by a thermal oxidation method can be critical for the morphology transformation from 2D NFs to 1D NRs. The resulting hematite NR photoanodes show high efficiency toward solar water splitting with improved light harvesting capabilities, leading to an enhanced photoresponse due to the artificially formed oxygen vacancies.     

Retracted: Dual Effects of Nanostructuring and Oxygen Vacancy on Photoelectrochemical Water Oxidation Activity of Superstructured and Defective Hematite Nanorods

An Ar atmospheric treatment is rationally used to etch and activate hematite nanoflakes (NFs) as photoanodes toward enhanced photoelectrochemical water oxidation. The formation of a highly ordered hematite nanorods (NRs) array containing a high density of oxygen vacancy is successfully prepared through in situ reduction of NFs in Ar atmosphere. Furthermore, a hematite (104) plane and an iron suboxide layer at the absorber/back‐contact interface are formed. The material defects produced by a thermal oxidation method can be critical for the morphology transformation from 2D NFs to 1D NRs. The resulting hematite NR photoanodes show high efficiency toward solar water splitting with improved light harvesting capabilities, leading to an enhanced photoresponse due to the artificially formed oxygen vacancies.     

高压辊磨对赤铁矿粉球团矿焙烧性能的影响

采用管式焙烧炉对一种赤铁矿粉球团的预热焙烧性能进行了研究,结果表明该赤铁矿球团预热焙烧性能较差,预热温度要达到1070℃,焙烧温度要达到1250℃时其预热焙烧球团的抗压强度才能达到生产要求.对该矿粉进行高压辊磨预加工后,其预热和焙烧性能得到改善,其预热和焙烧温度可分别降低70℃和50℃.进一步的研究结果表明,高压辊磨预加工赤铁矿粉后,小于5μm 微细颗粒含量增加,使焙烧球团的孔隙率降低,有利于Fe2 O3晶粒形成大片的晶桥连接,使得焙烧球团抗压强度得到提高.