Separation of hematite from banded hematite jasper(BHJ) by magnetic coating

The separation of iron oxide from banded hematite jasper(BHJ) assaying 47.8% Fe, 25.6% Si O2 and 2.30%Al2O3 using selective magnetic coating was studied. Characterization studies of the low grade ore indicate that besides hematite and goethite,jasper, a microcrystalline form of quartzite, is the major impurity associated with this ore. Beneficiation by conventional magnetic separation technique could yield a magnetic concentrate containing 60.8% Fe with 51% Fe recovery. In order to enhance the recovery of the iron oxide minerals, fine magnetite, colloidal magnetite and oleate colloidal magnetite were used as the coating material. When subjected to magnetic separation, the coated ore produces an iron concentrate containing 60.2% Fe with an enhanced recovery of56%. The AFM studies indicate that the coagulation of hematite particles with the oleate colloidal magnetite facilitates the higher recovery of iron particles from the low grade BHJ iron ore under appropriate conditions.     

广西某赤褐铁矿选矿试验研究

对广西某含铁品位为52．07％、磁性率（FeO／TFe）为2．11％的难选赤褐铁矿矿石进行理化性能分析和矿物工艺学研究,并进行了强磁选、还原焙烧－磁选选矿试验,确定还原焙烧磁选可以获得较好的选别指标为：精矿铁品位达63．27％,产率达82．7％,铁回收率95．99％,有害元素硫,磷都较低,Si02、Al2O3、CaO、MgO的含量都能满足高炉冶炼的要求,属于优质铁精矿．     

Adsorbability of Mycobacterium phlei on hematite surface

The adsorption of microorganisms on the mineral surface is the base of microorganisms that are considered as mineral processing reagents. The principles of the use of a highly hydrophobic and negatively charged bacterium, Mycobacterium phlei, as a flocculating-flotating agent for finely divided hematite were investigated. The flocculating-floating recovery is strongly dependent on the pH and the dosage of the bacterium. Generally the pH should be controlled over the range of 5.5-7, and the dosage should be controlled about 16 mg/L. The infrared spectrometry analysis indicates that the six functional groups of M. phlei, substituted aromatic compound groups, -（CH2） n-groups, -CH2（-CH3） groups, carbonyl groups, aromatic hydrocarbon groups, and carboxyl groups, are on the hematite surface, among which the first five ones contribute physical adsorption and only the carboxyl groups provide chemisorption. Microscopic analysis reveals that the dimensions and tight aggregation degree of the flocs of hematite particles formed by M. phlei are also impacted by the pH and the content of M. phlei in flotation.     

Phase transformation in suspension roasting of oolitic hematite ore

Suspension roasting followed by magnetic separation is a promising method to upgrade oolitic hematite ore.An oolitic hematite ore was roasted using suspension roasting technology at different temperatures.The phase transformation for iron minerals was investigated by XRD and Mossbauer spectrum,and the characteristics of roasted product were analyzed by VSM and SEM-EDS.Results indicate that the magnetic concentrate is of 58.73% Fe with iron recovery of 83.96% at 650 °C.The hematite is rapidly transformed into magnetite during the roasting with transformation ratio of 92.75% at 650 °C.Roasting temperature has a significant influence on the phase transformation of hematite to magnetite.The transformation ratio increases with increased temperature.After roasting,the magnetic susceptibility is significantly improved,while iron ore microstructure is not altered significantly.     

广西某赤褐铁矿选矿试验研究

对广西某含铁品位为52.07%、磁性率(FeO/TFe)为2.11%的难选赤褐铁矿矿石进行理化性能分析和矿物工艺学研究,并进行了强磁选、还原焙烧—磁选选矿试验,确定还原焙烧—磁选可以获得较好的选别指标为:精矿铁品位达63.27%,产率达82.70%,铁回收率95.99%,有害元素硫,磷都较低,SiO2、Al2O3、CaO、MgO的含量都能满足高炉冶炼的要求,属于优质铁精矿.     

Hexagonal hematite platelets synthesized from pyrite cinders by hydrothermal process

Well-crystallized hexagonal hematite (α-Fe2O3) platelets were synthesized by hydrothermal process,using a highly concentrated ferric hydroxide as precursor.The precursor was prepared by adding ammonia to the ferric sulfate solution which was obtained by leaching pyrite cinders with sulfuric acid.Structure and morphology of the synthesized products were investigated by X-ray diffraction,scanning electron microscope,transmission electron microscope and selected area electron diffraction.The results reveal tha...     

冷却方式对焙烧鲕状赤铁矿磨矿性能影响

鲕状赤铁矿有用矿物嵌布粒度细,磨矿成本高,属于典型难选铁矿石。磁化焙烧-磁选工艺是分选此类难选铁矿石的有效方法,研究了不同冷却方式对磁化焙烧矿的磨矿性能产生的影响.鲕状赤铁矿进行磁化焙烧后分别隔绝空气密闭冷却、水淬及空气中自然冷却,进行粒度筛析和磨矿试验.发现焙烧后矿石粒径变粗,从原矿的平均粒径为0.069 9mm至密闭冷却、水冷和自然冷却焙烧矿的0.088 2mm、0.084 3mm、0.087 0mm.相同磨矿条件下,原矿、密闭冷却焙烧矿、水冷焙烧矿和自然冷却焙烧矿-0.045mm含量分别为84.89%、83.89%、76.51%、77.14%.表明磁化焙烧使鲕状赤铁矿变得更为难磨,密闭冷却时磨矿效果最佳,自然冷却次之,水冷最差.     

羟基丁二酸对α－Fe_2O_3单分散溶胶的絮凝──稳定性

研究了羟基酸系列之一的羟基丁二酸（苹果酸）体系对α－Ｆｅ＿２Ｏ＿３单分散溶胶稳定性的影响，讨论了该体系的絮凝机理．实验表明：①羟基丁二酸对α－Ｆｅ＿２Ｏ＿３溶胶的聚沿作用有别于一般电解质．②影响该体系的絮－稳定性的主要因素是体系的酸度和絮凝剂浓度．③羟基丁二酸对α－Ｆｅ＿２Ｏ＿３单分散溶胶的絮凝和再稳定是受表面化学反应所控制．属于特殊吸附絮凝．     

Magnetizing roasting mechanism and effective ore dressing process for oolitic hematite ore

Magnetizing roasting of oolitic hematite ore from western Hubei Province was investigated.The mechanism for reduction roasting of oolitic hematite ore was discussed and analyzed.It is found that flash magnetizing roasting-magnetic separation process is a promising approach for the processing of oolitic hematite ore from western Hubei Province.     

Facile synthesis of uniform hollow hematite sub-micro spheres with controllable shell thickness

A simple method was developed to prepare the uniform hematite hollow submicro-spheres with controllable structure and different diameter based on monodisperse poly(styrene-co-acrylic acid) [P(St-co-AA)] particles. The structure and formation mechanism of the hollow spheres were investigated in detail. The control mechanism of shell thickness was also discussed. The results indicated that the shell thickness and coarseness of the synthesized core-shell hematite hollow spheres could be tuned simply by the surface carboxyl content of the P(St-co-AA) particles. This method provided a new approach for the structure control in the preparation of hollow spheres. A Brunauer-Emmett-Teller (BET) test shows that the prepared hollow spheres have large surface areas which were decreased along with the increase of the diameter. The magnetic properties of the as-obtained hematite hollow spheres were investigated. The result showed that the coercivity and saturated magnetization were increased along with the increase of the shell thickness, and the remanent magnetization was increased along with the decrease of the diameter.     

Fragmentation mechanism of low-grade hematite ore in a high pressure grinding roll

The fragmentation mechanism of low-grade hematite ore in a high pressure grinding roll(HPGR) was studied based on the characteristics of comminuted products at different specific pressure levels. The major properties included the reduction ratio, liberation, specific surface energy, and specific surface area. The results showed that the fracture of low-grade hematite ore in HPGR was an interactive dynamic process in which the interaction between coarse particles of gangue minerals and fine particles of valuable minerals was alternately continuous with increased compactness and compacting strength of materials. Within a range of 2.8–4.4 N/mm~2, valuable minerals were crushed after preferentially absorbing energy, whereas gangue minerals were not completely crushed and only acted as an energy transfer medium. Within a range of 4.4–5.2 N/mm~2, gangue minerals were adequately crushed after absorbing the remaining energy, whereas preferentially crushed valuable minerals acted as an energy transfer medium. Within a range of 5.2–6.0 N/mm~2 range, the low-grade hematite ore was not further comminuted because of the "size effect" on the strength of materials, and the comminution effect of materials became stable.     

鲕状赤铁矿磁化焙烧—磁选—反浮选降磷试验

鄂西宁乡式鲕状赤铁矿嵌布粒度极细,SiO2、Al2O3、P等杂质含量高,用其生产的铁精矿很难达到冶炼要求.针对铁品位为43.76%,磷含量为0.84%的鄂西鲕状赤铁矿进行提铁降磷试验研究,通过对磁化焙烧温度、磁化焙烧时间、还原煤的配比等影响因素的条件试验,确定在焙烧时间60 min,焙烧温度750℃,还原煤11%(质量比)的最佳焙烧条件.焙烧产品磨矿至-0.038 mm占80.54%、用永磁选机进行弱磁选,获得了铁品位54.10%、铁回收率93.19%、磷含量0.80%的粗铁精矿.进行反浮选药剂制度试验,得到了铁品位58.95%、铁综合回收率80%、磷含量0.50%的铁精矿,其最佳浮选药剂制度为NaOH 750 g/t,淀粉800 g/t,石灰500 g/t,RA-715 750 g/t,G310 107.73 g/t,浮选温度30℃.在此浮选制度下,进行一粗一精试验,精选石灰和捕收剂用量减半,可得铁品位59.87%,磷含量降至0.28%,综合回收率71.08%,综合试验结果表明,本文探索的工艺流程具有很大的可行性,能够为鲕状赤铁矿的选矿利用提供参考.     

Effect of butanol on flotation separation of quartz from hematite with N-dodecyl ethylenediamine

In order to investigate the effect of butanol on quartz flotation when N-dodecyl ethylenediamine(ND)was used as collector, single mineral flotation and artificial mixed mineral(hematite and quartz were mixed at a mass ratio of 3:2) separation were conducted in the laboratory. Experimental results indicated that addition of butanol could improve the collecting performance of ND on quartz and enhance the floatability of quartz. Best flotation recovery of quartz was obtained when butanol was mixed with ND at a mass ratio of 1:1. Moreover, the molecular structure of alcohols had a significant effect on mineral recovery. Best separation efficiency could be obtained when tert-butanol was added as it had the largest cross-sectional area. Zeta potential measurements indicated that alcohols could strengthen electrostatic adsorption between quartz and collector. Molecular dynamic simulations revealed that co-adsorption of alcohols along with ND had taken place on the quartz surface, and ND/tert-butyl combinations were more easily absorbed on the quartz surface.     

鞍钢使用大比例赤铁矿生产氧化球团的研究

针对鞍山矿业大孤山球团厂生产氧化球团用磁铁矿不足的问题,进行了大比例赤铁矿生产氧化球团的实验室研究和半工业化链蓖机—回转窑生产试验．实验室研究结果表明,鞍千赤铁矿配比不超过40％时,球团矿抗压强度大于2500N／个,低温还原粉化指数RDI＋3.15大于82.05％,还原膨胀指数RSI小于15.02％,均能满足现代化大高炉生产的要求．工业试验表明,鞍千赤铁矿配比不超过40％时,生产稳定,产品质量全面满足鞍钢炼铁原料的技术要求．2011年进行了推广应用,生产实际结果表明,2011年比基准期增长创效4.2亿元．     

Flocculation performance and mechanism of hydroxamate flocculants on synthetic hematite or goethite suspension

Suitable amounts of Al(OH)3, Na OH and synthetic hematite or goethite were taken to be digested under the simulated condition of the Bayer process and subsequently diluted with simulative Bayer red mud lotion, then the synthetic hematite or goethite suspension was obtained. The flocculation effect of self-made modified poly(acrylic acids) flocculants containing hydroxamic acid groups(abbreviated as HPAA) on the synthetic hematite or goethite suspension was studied. The experimental results show that with the increase of the dosages of added flocculants, the average settling rate of the synthetic hematite or goethite suspension in the first 1min speeds up, the supernatant solids decrease. It could also be found that there is generally a decrease in the average settling rate of the synthetic hematite or goethite suspension in the first 1 min with increasing solid content of the suspension. When the solid content of hematite or goethite of the suspension is 50 g/L with 240 g/t dosage of HPAA, HPAA has a better flocculation effect on the synthetic goethite suspension than on the synthetic hematite suspension. The adsorption mechanism of HPAA on the surface of hematite or goethite was investigated by Fourier transform infrared spectroscopy(FT-IR) and X-ray photoelectron spectroscopy(XPS).All the results suggest that HPAA is adsorbed on the hematite or goethite surface by a chemisorption, and it has a stronger adsorption on the goethite surface than on the hematite surface.     

Effect and mechanism of siderite on reverse anionic flotation of quartz from hematite

Reverse flotation technology is one of the most efficient ways to improve the quality and reduce impurity of iron concentrate. Mineral processors dealing with hematite face a challenge that the flotation results of reverse flotation of hematite are poor in presence of siderite using fatty acid as collector, starch as depressant of iron minerals and calcium ion as activator of quartz at strong alkaline pH. In this work, the effect of siderite on reverse anionic flotation of quartz from hematite was investigated. The effect mechanism of siderite on reverse flotation of hematite was studied by solution chemistry, ultraviolet spectrophotometry(UV) and Fourier transform infrared spectroscopy(FTIR). It was observed that siderite had strong depressive effect on quartz in flotation using sodium oleate as collector, corn starch as depressant of iron minerals and calcium chloride as activator of quartz at strong alkaline pH. The starch was adsorbed onto calcium carbonate by chemical reaction which was formed by CO~(2-)_3 from siderite dissolution and Ca~(2+) from calcium chloride as activator of quartz and precipitated on the surface of quartz, which resulted in improving the hydrophilic ability of quartz.     

Study on kinetics of thermal decomposition of low LOI goethetic hematite iron ore

In the present study, the kinetics of thermal decomposition of hydrated minerals associated in natural hematite iron ores has been investigated in a fixed bed system using isothermal methods of kinetic analysis. Hydrated minerals in these hematite iron ores are kaolinite, gibbsite and goethite, which contribute to the loss on ignition(LOI) during thermal decomposition. Experiments in fixed bed have been carried out at variable bed depth(16, 32, 48 and 64 mm),temperature(400-1200 ℃) and residence time(30,45, 60 and 75 min) for iron ore samples. It is observed that beyond a certain critical bed depth(16 mm), 100% removal of LOI is not found possible even at higher temperature and higher residence time. Most of the solid-state reactions of isothermal kinetic analysis have been used to analyze the reaction mechanism. The raw data are modified to yield fraction reacted "α" versus time and used for developing various forms of "α" functions.f(α) is the inverse of first derivative of g(α) with respect to α. The study demonstrates that decomposition of hydrated mineral in hematite follows the chemical kinetics.The estimated activation energy values in all the experimental situations are found to high, of the order of 60 kJ/mol, reinstating that the reactions are indeed controlled by moving phase boundary and random nucleation.     

某鲕状赤铁矿流化床燃煤还原焙烧-磁选研究

运用小型循环流化床锅炉,针对铁品位为49.20%、磷质量分数为1.16%的湖北某鲕状赤铁矿进行磁化焙烧-磁选试验研究.试验结果表明,将粒径为106～150 μm的鲕状赤铁矿在700 ℃下焙烧15 min,选取磨矿后粒径在74 μm以下的颗粒质量分数为85%的焙烧矿物,运用湿式磁选管在139.22 kA/m的磁场强度下对筛选后的焙烧矿物进行磁选抛尾,可以获得铁品位为55.12%、全铁回收率为70.11%、磷质量分数为0.67%的铁精矿.研究表明,运用循环流化床局部还原性气氛高速磁化焙烧铁矿石是可行的,运用该磁化焙烧-磁选工艺流程可以达到一定的提铁降磷效果.