菱铁矿与赤铁矿浮选分离试验研究

通过菱铁矿和赤铁矿单矿物的浮选试验,发现在强碱性条件下,自制的新型阴离子捕收剂TS对菱铁矿有很好的选择性捕收性能,改性水玻璃对赤铁矿有很好的选择性抑制作用。采用这两种药剂对菱铁矿和赤铁矿的人工混合矿进行浮选验证,获得了良好的分离指标。光电子能谱分析结果表明:TS可在菱铁矿表面大量吸附,改性水玻璃可在赤铁矿表面大量吸附;两种药剂的吸附均属于化学吸附,其中TS是通过其键合原子硫与菱铁矿表面的亚铁离子发生作用。     

Dissolution and rheological behaviour of hematite and quartz particles in aqueous media at pH 1

In this study we investigate isothermal, atmospheric acid dissolution behaviour of quartz and hematite minerals which constitute two of the predominant host gangue phases of typical low grade limonitic laterite ores. Batch dissolution tests were carried out on 57 wt.% solid dispersions for 4 h at pH 1 and 25 and 70 °C to establish the influential role of oxide mineralogy/chemistry on rheology and leaching behaviour. The results show that the two minerals displayed a weakly temperature and time-independent, non-Newtonian rheological behaviour with low shear yield stresses (<4 Pa) and viscosities (9–17 mPa s). Hematite dissolution rate was significantly higher compared with that of quartz under similar conditions. Quartz dissolution mechanism was substantially volume diffusion controlled at lower agitation rate (600 rpm) whilst for hematite it was both volume diffusion and chemical reaction controlled. These mechanisms reflected activation energies of 17.7 ± 0.9 and 28.5 ± 1.4 kJ/mol, respectively, for quartz and hematite. At 800 and 1000 rpm, dissolution of both minerals was chemical reaction-controlled with similar activation energies (32.6 ± 1.7 and 32.2 ± 1.6 kJ/mol). The findings underscore the need for higher agitation rates and elevated temperatures, to overcome both volume diffusion and chemical reaction limitations for enhanced acid leaching of these two fairly refractory oxides studied herein.     

Synthesis of magnetite powder from iron ore tailings

Iron ore tailing—a waste material of mineral beneficiation plants, is used as a source of iron for synthesizing magnetite powder. Iron ore tailings containing 15.98% Fe₂O₃, 83.36% SiO₂ and 0.44% Al₂O₃ have been subjected to HCl digestion on a hot plate to extract the entire amount of Fe₂O₃ as FeCl₃. A portion of extracted FeCl₃ solution has been used to convert it to FeCl₂ via metallic iron formation by using NaBH₄ as a reducing reagent. Then, the left out FeCl₃ solution and derived FeCl₂ solutions (from FeCl₃) are mixed in an appropriate molar ratio (2:1) for synthesizing magnetite powder by the addition of alkali solution. The magnetite powder samples have been characterized by means of powder XRD, SEM, vibrating sample magnetometer and laser particle size analyzer. XRD study confirms the formation of magnetite phase. The magnetite particles synthesized in different ways show varying degrees of magnetization behavior which is attributed to the change in their particle size induced by the use of different precipitating reagents.     

Iron oxide synthesis using a continuous hydrothermal and solvothermal system

Iron oxide synthesis via a continuous hydrothermal and solvothermal reaction were studied. In the hydrothermal synthesis, fine α-Fe₂O₃ (hematite) particles were obtained at 250–420 °C and 30 MPa. The α-Fe₂O₃ crystals were grown in sub-critical water via a dissolution and precipitation process. The growth of α-Fe₂O₃ crystals in supercritical water was suppressed due to the rather low solvent power of water. Crystalline Fe₃O₄ was obtained as the temperature was raised above the supercritical state in the solvothermal preparation. Isopropanol (IPA) was oxidized in acetone which provided a reducing atmosphere. Acetone molecule adsorption onto the Fe₃O₄ particle surface inhibited crystallite growth.     

Nano encapsulation of hematite into silica matrix as a red inclusion ceramic pigment

The hematite as a natural and non toxic red inorganic pigment has been known since prehistoric times but color shade of hematite becomes unstable with temperature and need to protect with a suitable matrix. The best red shades are obtained by the inclusion of hematite in silica matrixes. A co-precipitation method has been applied in order to improve the inclusion efficiency of hematite into silica crystals; iron sulfate was used as Fe precursor and precipitating agent was ammonia. Effects of the single flux agent (NaF and NaCl) and binary flux agent (NaF·NaCl), have been studied. Continuous changes in color were measured by comparing L*-a*-b* values of the heated samples. TEM analysis on heat treated powders shows some hematite single crystals that were occluded with silica crystals successfully. Due to its chemical and thermal stability, the hematite/silica pigment may be considered as a suitable red pigment for ceramic manufacturing by fast firing cycles.     

Morphology control of the hematite photoanodes for photoelectrochemical water splitting

The morphology of hematite photoanode is a significant relevant factor in its photoelectrochemical (PEC) performance. Hematite nanowires and nanocubes as well as nanorods with intentional Sn doping were prepared by hydrothermal processes containing disparate additives. The band-gap decreases in the sequence of nanowires, nanorods and nanocubes. Compared with nanorods, nanowires show higher carrier density but a lower light absorbance. With both inhibited bulk and surface charge recombination, nanowires achieve an enhanced photocurrent. Meanwhile, it is more complicated for the charge conversion in the hematite nanocubes. Light absorption is limited due to the compact arrangement of nanocubes. Besides, nanocubes show a highly oriented (104) plane which is unfavorable to the charge conductivity. Despite the negative factors hindering its PEC performance, the extremely high carrier density in the nanocubes benefits to the distinctly enhanced photocurrent collected from the hematite samples annealed at 550 and 650 °C respectively. However, the superiority of hematite nanocubes annealed under 800 °C is restricted by the high onset potential. Still, attributed to the high surface charge transfer efficiency, the hematite nanocubes achieve the highest photocurrent among the samples at biases above 1.3 V. Electrodes made of hematite nanorods, nanowires and nanocubes annealed at 800 °C achieve a photocurrent of 1.01, 1.30 and 1.40 mA cm⁻² at 1.6 V vs. RHE, respectively.     

蒸压制度对赤铁矿尾矿蒸压砖强度的影响

研究了蒸压制度对赤铁矿尾矿-石灰-黄沙体系蒸压砖抗压强度的影响,确定了原料中尾矿、石灰、黄沙的质量比为70∶15∶15,成型压力为20 MPa的砖坯的适宜蒸压制度为：升压时间2.1 h,蒸汽压力1.2 MPa,恒压时间6 h,降压时间3.5 h。利用XRD、DSC对蒸压砖抗压强度形成机理进行了探讨,结果表明,赤铁矿尾矿－石灰－黄沙体系在1.2 MPa蒸汽压力下首先生成了水石榴石,而后生成CSH(Ⅰ)凝胶和高强度的托勃莫来石,随着蒸压时间的延长,托勃莫来石逐渐转化成强度相对较低的硬硅钙石。     

SLon－2000立环脉动高梯度磁选机的研制

针对红矿选矿工业生产中存在的一些问题研制了ＳＬｏｎ－２０００立环脉动高梯度磁选机，在鞍钢弓长岭选矿厂进行了六个月分选赤铁矿的工业试验，证明了该机具有宫集比大、分选效率高、分选粒度范围宽、适应性强、运转可靠的优点，尤其是其棒形磁介质长期保持清洁不堵塞，克服了高梯度磁选机网介质较难维护和平环强磁选机齿板较易堵塞的缺点。     

SLon─1750立环脉动高梯度磁选机的研制与应用

针对马钢姑山铁矿用于赤铁矿粗选作业的SQC—6—2770A型湿式强磁选机精矿品位偏低、尾矿品位偏高、齿板较易堵塞的问题，研制了SLon—1750立环脉动高梯度磁选机，取代1台SQC－6一2770A磁选机进行工业对比试验，证明了该机具有富集比较大，选矿效率高，磁介质不堵塞的优点。     

Magnetite surface morphology during hematite reduction with CO/CO2 at 1073 K

The morphology of the magnetite phase that formed during the hematite/magnetite reduction process was studied. A very dense hematite ore of very high grade iron content (Fe = 69%) was used. Annealed ore specimens of about 2 g and 5 × 5 × 1 mm size were polished and reduced with 20%CO-80%CO₂ gaseous mixtures of total gas flow rate 1 L/min at 1073 K. The morphological observation of the surface of the specimens and its cross-section after reduction was detected by SEM. The initial formation of magnetite phase nuclei was detected as needles in shape. These needles of about 500-1000 nm diameter and length 10-15 μm come in a random distribution in the reduced surfaces. These needles are accumulated after forming a large centered area of a porous magnetite phase inside each surface grain.