Yanjun Li

Separation and recovery of iron from a low-grade carbonate-bearing iron ore using magnetizing roasting followed by magnetic separation

ABSTRACT In this study, a process of magnetizing roasting followed by low-intensity magnetic separation (MR-LMS), which is used to separate and recover iron from a low-grade carbonate-bearing iron ore (containing 34.6 wt.% Fe), was investigated. A magnetic concentrate containing 65.4 wt.% Fe with an iron recovery rate of 92.6 wt.% was obtained under optimal conditions: roasting temperature of 800°C, roasting time of 8 min, bitumite ratio of 10:100, grinding fineness of around 85 wt.% passing 38 µm, and magnetic intensity of 0.12 T. In addition, the phase transformation and magnetic properties were analyzed by X-ray diffraction (XRD) and vibrating sample magnetometry (VSM) to reveal the mechanism.

Recovery of boron from high-boron iron concentrate using reduction roasting and magnetic separation

The comprehensive utilization of abundant high-boron iron concentrate is of particular significance to China, and the high-boron iron concentrate has not yet been utilized as a source for boron at an industrial scale due to its complex mineralogy and fine mineral dissemination. An innovative method was proposed for recovery of boron and iron from high-boron iron concentrate by reduction roasting and magnetic separation. The effects of reduction temperature and roasting time were investigated and their optimum conditions were determined. The mineralogical changes during roasting were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results showed that the pyrrhotite (FeS) contained in the high-boron iron concentrate and the new-formed FeS-Fe solid solution softened or melted at high temperatures owing to their low melting points, and then decreased the metallic iron ratio and accelerated the growth of metallic iron particles. Meanwhile, the magnetite and szaibelyite were converted into metallic iron and suanite, respectively. Consequently, boron was readily enriched into the non-magnetic product and the metallic iron was aggregated to the magnetic concentrate by magnetic separation. Boron recovery of 88.6% with corresponding B2O3 content of 14.5% and iron recovery of 95.1% with an iron grade of 92.7% were achieved when high-boron iron concentrate was reduced at 1125 °C for 150 min. Besides, the boron reactivity of the boron-rich non-magnetic product was up to 80.8%.

Formation and characterization of metallic iron grains in coal-based reduction of oolitic iron ore

To reveal the formation and characteristics of metallic iron grains in coal-based reduction, oolitic iron ore was isothermally reduced in various reduction times at various reduction temperatures. The microstructure and size of the metallic iron phase were investigated by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and a Bgrimm process mineralogy analyzer. In the results, the reduced Fe separates from the ore and forms metallic iron protuberances, and then the subsequent reduced Fe diffuses to the protuberances and grows into metallic iron grains. Most of the metallic iron grains exist in the quasi-spherical shape and inlaid in the slag matrix. The cumulative frequency of metallic iron grain size is markedly influenced by both reduction time and temperature. With increasing reduction temperature and time, the grain size of metallic iron obviously increases. According to the classical grain growth equation, the growth kinetic parameters, i.e., time exponent, growth activation energy, and pre-exponential constant, are estimated to be 1.3759 ± 0.0374, 103.18 kJ·mol−1, and 922.05, respectively. Using these calculated parameters, a growth model is established to describe the growth behavior of metallic iron grains.

Influence of Organic Additives on Shape and Adsorbing Properties of Nano-Fe3O4 Particles

Nano-Fe3O4 powders were prepared by chemical co-precipitation method. The granularity, morphology and absorbing properties of the magnetite nanoparticles were characterized by XRD, SEM, TEM and complex permeability. The effects of organic additives to the granularity, morphology and microwave absorption property of nanosized magnetic Fe3O4 were studied. The results show that the organic additives have great influence on the morphology of nano-Fe3O4 particles. Spherical nano-Fe3O4 is prepared by oxalic acid. And the absorption property of nano-Fe3O4 is better.

Research on Preparation of Mesoporous Zeolite by Template Method

In this paper, the preparation of mesoporous zeolite by template method is studied that the mesoporous zeolite is made up of pure silica source and pure aluminum source. The synthesis mechanism of mesoporous zeolite is investigated according to the characterization results of FTIR, SEM and N2 adsorption-desorption. The results shows that the water glass and sodium aluminate as the partial raw materials of synthesis process, P123 as the template, reaction at 42°C for 20h, aging at 54°C for 48 h, calcining at 550°C for 5 h. The average pore size of prepared mesoporous zeolite is 6.4nm and the specific surface area is 394.65m2/g. The FTIR shows that the microstructure of the prepared samples is similar to zeolite ore, and the SEM result indicates that the micromorphology of the product is uniform and pore size is within the mesoporous range.

Selective flotation of siderite and quartz from a carbonate-containing refractory iron ore using a novel amino-acid-based collector

A novel and highly-efficient amino-acid-based collector, α-ethylenediamine lauric acid (αEDA-LA), was studied to selectively beneficiate carbonate-containing refractory hematite ores. Single mineral and synthetic mixture flotation tests were carried out to investigate its floating performance. Zeta potential, fourier transform infrared spectroscopy (FTIR) and Density Functional Theory-based molecular simulation were used to identify the adsorption mechanism. The flotation results showed that quartz could be collected effectively at pH 11.0-12.0 in the reverse flotation. For siderite, the recovery peaked at 83.4% at pH 8.0, where siderite presented different floatability from magnetite and hematite. Exploiting such difference, the separation of siderite could be achieved. Zeta-potential measurements showed that α-EDA-LA adsorption on the surfaces of siderite and quartz decreased the corresponding zeta potentials at pH of 8.0-10.0 and 8.0-12.0, respectively. This means the adsorption overcome the electrostatic repulsion between α-EDA-LA and the mineral surfaces. The molecular simulation indicated that no chemisorption took place between α-EDA-LA and quartz. FTIR analysis suggested that α-EDA-LA was adsorbed on quartz via hydrogen bonding. The adsorption of α-EDALA on siderite surface was dominated by chemisorption, while further enhanced by hydrogen bonding. This study filled the gap in the research on siderite flotation reagents and its adsorption mechanism.

The effects of various activators on flotation performance of lime-depressed pyrrhotite

ABSTRACT The effects of various activators on the flotation behaviour of lime-depressed pyrrhotite (FeS1.1) were investigated. The activation mechanisms were studied using electrochemical analysis, Fourier transform infrared spectroscopy, zeta potential measurements, and X-ray photoelectron spectroscopy. Micro-flotation results showed that the floatability of pyrrhotite declined sharply from 97.6% to 5.1% with the addition of lime. The flotation performance improved with the addition of both acid and salt activators; oxalic acid was the best activator, with a recovery > 97.0%. Ca- and Fe-based hydrophilic films formed on the lime-depressed pyrrhotite surface, preventing the adsorption and oxidation of the collector on the pyrrhotite surface. The activator increases its own surface potential to prevent the production of hydrophiles, and also removed hydrophiles from the pyrrhotite surface. In addition, the oxalic acid formed a stable chelate and removed hydrophilic material from the pyrrhotite surface. This study contributes to understanding the flotation mechanism and activation of lime-depressed pyrrhotite.

Suspended Magnetic Roasting Study of Fine Grained Iron Ore

Suspension roasting furnace was used as the reactor of magnetic roasting of fine grained siderite, and the N2 was used as the conveying gas. The results show that, the siderite ore be roasted at the conditions of gas velocity is 1.7m/s, and the roasted time is 12.35s, according to magnetic separation can obtained iron concentrate grade is 65.04%, and recovery rate is 93.03%.

An Iron Ore Beneficiation Test of a Region in Anshan

This test is in relation to a low-grade co-selected and mixed concentrates that produced from weak magnetic– magnetic beneficiation. Through the flotation tests step by step and control of variables to study the changes of starch’s amount and inhibitor collector’s amount in the impact of test results in the anti-flotation and the flotation process At the end, we received a grade of 55.65%, 57.19% recovery of iron ore products, iron ore products calcined at 800 °C for 40min under the conditions you can get concentrate grade of 60.14% of the product.

Study on Deep Reduction and Efficient Separation of Lingyang Iron Ore

The test for deep reduction and efficient separation of Lingyang iron ore from Linjiang that cannot be separated and utilized by any conventional mineral processing technology was conducted in the Laboratory, and the research results showed that iron from Lingyang iron ore was recovered effectively. In this paper, the effect of reduction temperature, time and coal content on reduction was analyzed, and the process of deep reduction and efficient magnetic separation was investigated. Furthermore, on such optimum conditions of deep reduction as reduction temperature 1275°C, time 50min, and coal content 40%, the reduction products were separated in the flowsheets of magnetic separation after fine grinding and the iron powder products with iron grade 79.58% and recovery 62.77% were obtained.