鄂西某高磷鲕状赤铁矿磁化焙烧及浸出除磷试验

针对鄂西某高磷鲕状赤铁矿(铁品位43.50%),在实验室条件下采用磁化焙烧—磁选工艺获取铁精矿,并对该铁精矿进行酸浸、生物浸出除磷试验。研究结果表明,在焙烧温度850℃,焙烧时间25min,还原剂用量为矿石质量的5%,磨矿时间4min,磁场强度120kA/m条件下,得到铁精矿铁品位为54.92%,铁回收率为86.78%,P含量为0.83%;酸浸试验中矿浆浓度2%,分别用0.1mol/L的H2SO4,HNO3,HCl,草酸(C2H2O4),柠檬酸(C6H8O7)除磷,其中H2SO4除磷提铁效果最佳,铁精矿品位为57.98%,回收率为96.47%,除磷率为95.30%;生物浸出试验中矿浆浓度2%,用嗜酸氧化亚铁硫杆菌(At.f菌)对铁精矿作用后,磷含量为0.23%,用黑曲霉菌滤液对铁精矿作用后,磷含量为0.20%。     

Physical and photoelectrochemical characterizations of hematite α-Fe2O3: Application to photocatalytic oxygen evolution

The physical properties and photoelectrochemical characterization of α-Fe₂O₃, synthesized by co-precipitation, have been investigated in regard to solar energy conversion. The optical gap is found to be 1.94 eV and the transition is indirectly allowed. The chemical analysis reveals an oxygen deficiency and the oxide exhibits n-type conductivity, confirmed by a negative thermopower. The plot log σ vs 1/T shows linearity in the range (400-670 K) with the donor levels at 0.14 eV below the conduction band and a break at ∼590 K, attributed to the ionization of the donors. The conduction occurs by small polaron hopping through mixed valences Fe^2+/3+ with an electron mobility μ_400 K of 10⁻³ V cm² s⁻¹. α-Fe₂O₃ exhibits long term chemical stability in neutral solution and has been characterized photoelectrochemically to assess its activity as bias-free O₂-photoanode. The flat band potential V_fb (−0.45V_SCE) and the electron density N_D (1.63 × 10¹⁸ cm⁻³) were determined, respectively, by extrapolating the linear part to C⁻² = 0 and the slope of the Mott Schottky plot. At pH 6.5, the valence band (+1.35V_SCE) is suitably positioned with respect to the O₂/H₂O level (+0.62 V) and α-Fe₂O₃ has been evaluated for the chemical energy storage through the photocatalytic reaction: (, ΔG = 213.36 kJ mol⁻¹). The best photoactivity occurs in solution (0.025 M, pH 8) with an oxygen rate evolution of 7.8 cm³ (g catalyst)⁻¹ h⁻¹.     

Spray pyrolytically deposited nanoporous Ti doped hematite thin films for efficient photoelectrochemical splitting of water

Nanoporous hematite (α-Fe₂O₃) thin films doped with Ti⁴⁺ deposited by spray-pyrolysis were successfully used in photoelectrochemical splitting of water for solar hydrogen production. X-ray diffraction, field emission scanning electron microscopy, UV–visible absorption and photoelectrochemical studies have been performed on the undoped and Ti⁴⁺ doped hematite thin films. Morphology of α-Fe₂O₃ thin films was observed to be nanoporous, with increased porosity (pore size ∼12 to 20 nm) on increasing doping concentration. A significant decrease in the bandgap energy from 1.95 to 1.27 eV was found due to doping. α-Fe₂O₃ film doped with 0.02 M Ti⁴⁺ ions exhibited best solar to hydrogen conversion efficiency (photoconversion efficiency) of 1.38% at 0.5 V/SCE. Highest photocurrent densities of 0.34 mA/cm² at zero bias and 1.98 mA/cm² at 0.5 V/SCE were obtained by incorporating 0.02 M Ti⁴⁺ in α-Fe₂O₃, which are significantly larger than earlier reported values. Donor density (30.8 × 10²⁰ cm⁻³) and flatband potential (−1.01 V/SCE) obtained were also maximum for this sample. Hydrogen collected in 1 hr at Pt electrode with the best photoelectrode was 2.44 mL with 150 mW/cm² visible light source.     

桦树沟铁矿石工艺矿物学研究

酒钢矿业公司桦树沟矿开采向深部推进过程中,矿石性质发生了较大变化。为给矿山生产和工艺改造提供指导,对桦树沟待采铁矿石进行了工艺矿物学研究。结果表明:矿石全铁品位为29.74%,赤(褐)铁占总铁的67.62%,碳酸铁占总铁的26.66%;主要有用矿物为赤铁矿、菱铁矿,褐铁矿少量,含量分别为26.62%、16.52%和4.35%;脉石矿物主要为石英、碳酸盐矿物和绢云母等,其中,石英含量为25.33%。矿石的结构主要为自形—半自形晶结构、他形晶结构、交代结构和填隙结构;主要构造为块状构造、条带状构造、浸染状构造、网状构造和蜂窝状构造。赤铁矿主要以片状、纤维状、薄板状、针状、放射状、鳞片状集合体产出,集合体常形成致密的块体;菱铁矿多呈粒状及粒状集合体产出,以粗粒嵌布为主,与方解石、白云石、白云母、石英嵌布关系密切;褐铁矿主要以胶状、土状浸染分布在非金属矿物中,以及以细脉状、网状充填在其他矿物的粒间,有的以多孔状、蜂窝状嵌布在矿石中,粒度极不均匀。脉石矿物石英多以自形、半自形粒状集合体产出,粒度较均匀,常被碳酸盐矿物、白云母和绢云母等充填胶结;方解石和白云石主要以他形粒状、不规则状、脉状、网脉状产出,常与菱铁矿紧密共生形成集合体。     

餐饮废油制备JZQ-F捕收剂反浮选赤铁矿石试验研究

随着人们生活水平的提高,餐饮废油产量日益增大,其利用途径引起社会的广泛重视。若能用餐饮废油制备矿产品浮选药剂,则可实现餐饮废油的大宗利用。北京科技大学相关课题组经水浴加热、沉淀+离心除杂、脱色、皂化、萃取、酸化、水洗、改性等工序制得脂肪酸类捕收剂JZQ-F,用其对粒度为-200目占92.23%,Fe品位为43.91%,SiO_2含量为32.99%的鞍钢集团东鞍山烧结厂弱磁选—强磁选混合铁精矿进行了反浮选脱硅试验,结果表明,在矿浆pH=11(NaOH用量为1 200 g/t),苛性淀粉用量为1 350 g/t,CaO用量为600 g/t,JZQ-F用量为450 g/t情况下,采用1粗1精3扫流程处理混合铁精矿,可得到铁品位为66.58%、铁回收率为73.63%的反浮选铁精矿。动电位研究表明,矿浆pH=10~12,JZQ-F在石英表面发生了化学吸附,提高了石英表面的疏水性,而JZQ-F在赤铁矿表面不发生吸附,这为磁选铁精矿中石英与赤铁矿的分离创造了条件。红外光谱研究表明,只有被CaO活化的石英才可与JZQ-F发生化学吸附,因此,用JZQ-F反浮选脱除磁选铁精矿中的石英,必须用CaO对石英进行活化。     

锌铁离子浓度对赤铁矿法除铁的影响研究

本文针对赤铁矿沉铁技术,以纯硫酸亚铁和硫酸锌溶液为研究对象,研究了锌铁离子浓度对赤铁矿法除铁过程中沉铁效果的影响和赤铁矿渣硫铁含量的影响。结果表明：增加亚铁离子浓度,渣中硫的百分含量会升高,铁的百分含量会减少;在相同亚铁离子浓度条件下,增加锌离子浓度,沉铁效果会变差,渣中硫百分含量会降低,渣中铁百分含量会升高。     

羧甲基酰胺在赤铁矿反浮选中的抑制机理研究

为考察羧甲基酰胺抑制剂在赤铁矿反浮选脱硅中的应用效果,分别以聚丙烯羧酸(HPAM)、复配羧甲基酰胺DWP-3（由HPAM和小分子阴离子型抑制剂DNL按7∶3的质量比配制而成）为抑制剂,考察其对赤铁矿和石英单矿物可浮性的影响。单矿物浮选试验结果表明,DWP-3对石英的抑制作用较弱,对赤铁矿抑制作用相对较强,有利于赤铁矿反浮选脱硅。动电位检测和红外光谱测定结果表明：pH<2.95时,HPAM、DWP-3在石英表面存在静电吸附,pH>2.95时,HPAM、DWP-3在石英表面存在氢键吸附;pH<3.53时,HPAM、DWP-3在赤铁矿表面存在静电吸附,pH>3.53时,HPAM、DWP-3在赤铁矿表面存在氢键吸附和化学吸附。     

不同还原方法对赤铁矿粉金属化率的影响

对粒径40～160 μm的赤铁矿粉进行直接还原的实验研究,利用H2作为还原气体在竖直管式炉中流态化焙烧还原,利用固体C在马弗炉中静态堆积原位焙烧还原.结果表明,随着赤铁矿粉粒径变小、反应温度提高、反应时间增加、还原气体流量增大,赤铁矿还原速率增大,金属化率明显提高.以H2作为还原气体反应30 min,金属化率可达94.60％.煤基堆积静态直接还原赤铁矿粉,以同心圆布料,1100℃下还原3.5h,金属化率达到96.85％.     

Preparation and electrochemical performance of flower-like hematite for lithium-ion batteries

Flower-like hematite (α-Fe₂O₃) has been successfully prepared by heat-treatment from the iron(III)-oxyhydroxide precursor, which is obtained by the hydrolysis of FeCl₃ solution in the presence of NaClO. In this process, no templates or catalysts are required. SEM and TEM characterizations confirm that micro-flowers are composed of several dozen self-assembled nanopetals with the thickness of about 20 nm. On the basis of the morphology investigations in time-dependent experiments, the possible growth mechanism of the flower-like α-Fe₂O₃ is proposed, which is similar to a two-stage growth process. Furthermore, as an anode electrode material for rechargeable lithium-ion batteries, the flower-like α-Fe₂O₃ exhibits excellent electrochemical performance, which can be attributed to the high surface area induced by the flower-like structure, the short lithium diffusion length and the restriction of volume change of the Li⁺ insertion/extraction.     

Sn self-doped α-Fe2O3 nanobranch arrays supported on a transparent,conductive SnO2 trunk to improve photoelectrochemical water oxidation

We produced hierarchically branched Fe₂O₃ nanorods on a Sb:SnO₂ transparent conducting oxide (TCO) nanobelt structure as photoanodes for photoelectrochemical water splitting. Single-crystalline SnO₂ nanobelts (NBs) surrounded by Fe₂O₃ nanorods (NRs) were synthesized by thermal evaporation, then underwent chemical bath deposition and annealing. When Fe₂O₃ was crystallized by annealing, Sn was diffused from SnO₂ NBs and incorporated to Fe₂O₃ NRs, which was confirmed through Energy dispersive spectroscopy. Unlike previous high temperature sintering (∼800 °C), Sn doped hematite NRs were obtained at a low temperature (∼650 °C). This occurred since SnO₂ NBs directly connected to Fe₂O₃ NRs are an abundant source of Sn dopant. The 3D hematite NRs on SnO₂ NBs annealed at 650 °C produce a photocurrent density of 0.88 mA/cm² at 1.23 V vs. RHE, which is 3 times higher than that of hematite NRs on a fluorine doped tin oxide (FTO) glass substrate annealed at the same temperature. The enhanced photocurrent is attributed to the improved electrical conductivity of Fe₂O₃ NRs by Sn doping, the efficient electron transport pathway by TCO nanowire and the increased surface area by hierarchically branched structure.