Assessment and Mechanism Investigation of Selective Flocculation Process for Ultrafine Chromite Particle

During beneficiation of low-grade chromite ore, huge amounts of ultrafine tailings are generated and contain substantial metal values which need to be recovered. Selective flocculation technique is one of the processes for beneficiation of ultrafine particles. Here an attempt was made to establish selective flocculation process by using two types of synthetic mixtures. In addition to this, selective flocculation was also attempted on natural tailings. It was found that it is possible to enrich the chromite value using the selective flocculation process. The selectivity of the wheat starch to the chromite mineral was also investigated using image analysis, FTIR analysis, and zeta potential analysis.     

蛇纹石中微量钯的提炼

介绍了蛇纹石的熔融、酸解等处理过程 ,重点叙述了从蛇纹石中提取微量贵金属钯的工艺流程和操作方法。钯的提取率为 90 .5 %。     

铬铁矿中全铁的分析方法改进

采用了无汞测铁技术应用于铬铁矿中全铁的测定新方法。用甲基橙作SnCl2还原Fe^3＋的指示剂,再用K2Cr2O7标准溶液滴定亚铁。试验结果表明,该法简单、快速、准确可靠对环境无汞污染。     

Clean Chromite Production from Fine Chromite Tailings by Combination of Multi Gravity Separator and Hydrocyclone

Chromite is an important mineral used in the metallurgy, chemistry, and refractory industries. For this reason, beneficiation of chromite tailings is very important. In this study, the possibility of beneficiation of chromite tailings in the Uckopru/Fethiye-Turkey region by Hydrocyclone and Multi Gravity Separator (MGS) combination was investigated. The two signification operational parameters of hydrocyclone, which were diameter of apex and diameter of vortex, and the three signification operational parameters of MGS, which were drum speed, tilt angle, and wash water, were varied and the results were evaluated with the Central Composite Rotatable Design. The results of beneficiation studies showed that commercial concentrate containing 48.18% Cr₂O₃ was obtainable with a 69.79% rate of recovery.     

江西弋阳蛇纹石硫酸浸出过程工艺条件的优化研究

文章在常压、较低温度(<100℃)下,开展了江西弋阳蛇纹石硫酸浸出工艺条件的研究.以蛇纹石中氧化镁的浸出率为主要考察指标,通过单因素条件实验和正交实验,分别考察了蛇纹石酸浸反应温度、酸浸反应时间、硫酸溶液质量浓度、液固比等因素的变化对蛇纹石中氧化镁浸出率的影响,所得较佳的工艺条件为:酸浸反应温度95℃、酸浸反应时间5h...     

Micro-Bubble Flotation of Freshwater Algae: A Comparative Study of Differing Shapes and Sizes

This study investigates the effects of the morphology (shape and size) of differing algae species on the removal efficiency by the dissolved air flotation (DAF) process. Three selected shapes in this research are spherical (Microcystis sp.), oval (Chlamydomonas angulosa), and filamentous algae (Phormidium sp.), cultured in the laboratory under certain cultivated conditions. Physical properties of three differing algae were understood as morphology, size distribution, and zeta potential in various pHs. Under pH conditions of 4.5?7, all algae species showed negative charges: ?10 mV for filamentous shape, ? ?20 mV for oval shape, and ? ?40 mV for spherical shape. The size of these shapes ordered increasingly as spherical < oval < filamentous algae. In order to separate algae from water, positively charged bubbles were generated by adding a coagulant (as Al³⁺) and were applied at 10%, 20%, and 30% recycling ratio. Assessment of algae removal efficiency was shown by the number of the cells, total organic carbon (TOC), dissolved organic carbon (DOC), and the morphological changes (i.e., shape or size distribution). In terms of the number of cell, filamentous algae showed the greatest removal, i.e., 86% removal at 30% recycling ratio and 5 mg/L of Al³⁺ addition. For TOC and DOC removal perspectives, spherical algae showed the greatest removal above 80%. These results, therefore, confirm that the shapes and sizes of algae affect the removal process of bubble technology.     

由蛇纹石或其尾矿制取硅酸镁和超细氢氧化镁工艺的研究

研究了由蛇纹石或其尾矿制取硅酸镁和超细氢氧化镁的工艺。结果表明,在最佳工艺条件下制取的三硅酸镁、六硅酸镁和氢氧化镁产品的主要技术指标均达到了标准(或药典)要求,氢氧化镁颗粒呈近似球形,为超细粒子。     

A Parametric Study of a Portable Magnetic Separator for Separation of Nanospheres from Circulatory System

A portable magnetic separator was proposed for in-vivo biomedical applications. In this prototype design, a matrix of alternating, parallel magnetizable wires, and biocompatible tubing is immersed into an externally applied magnetic field. The wires are magnetized and high magnetic fields as well as field gradients are created to trap blood-borne flowing magnetic nanospheres in the tube. In this paper, a parametric investigation was carried out to evaluate the capture efficiency of flowing magnetic nanospheres by a separator unit consisting of single tubing and four wires. The parameters include: mean blood velocity (1 to 20 cm/s); magnetic field strength (0.1 to 2.0 T); sphere size (500 nm to 1000 nm in radii); sphere magnetic material (iron, two types of magnetite) and magnetite content in the spheres (0.05 to 0.8 by weight); wire material (nickel, stainless steel 430, and Wairauite); wire length (2.0 to 20 cm); wire size (0.125 to 1.0 mm in radii); tubing size at a fixed ratio of tubing to wire diameter of unity. The results show that capture efficiencies of the spheres of well over 90% were achievable under reasonable human physiological conditions, provided that the mean blood velocities were below about 5.0 cm/s. The results also show that the magnetic separator performance could be improved by maximizing the applied magnetic field strength up to about 1.0 T and by reducing the size of the unit with tubing and wires of equal radii. The results help further optimize a prototype magnetic separator suitable for rapid sequestration of magnetic nanospheres from the human blood stream while accommodating necessary clinical boundary conditions.     

Separation of Phosphorus and Magnetic Mineral Fines from Siderite Reductive Ore by Applying Magnetic Flocculation

The characteristics of siderite reductive ore and the ultrafine grinding-magnetic flocculation separation (MFS) of this ore were investigated in the present work. The results indicated that the iron phase in the raw ore was predominantly metallic iron with an iron particle size below 30 μm, and the phosphorus compound was apatite. By applying MFS to siderite reductive ore containing 37.14% Fe and 0.52 P, a concentrate assaying 66.37% Fe and 0.19 P with 74.32% recovery was produced. The iron recovery increased by 5.77% compared with the results of the conventional magnetic separation. The high efficiency in phosphorus removal and iron recovery achieved by the MFS process may be attributed to the adequate liberation of iron particles and the increase in magnetic force on the iron mineral fines in the form of flocs in a magnetic field.     

Optimal Recovery of Iron Values from a Low Grade Iron Ore using Reduction Roasting and Magnetic Separation

A low grade iron ore containing 51.6% Fe, 17.6% SiO₂, 4.3% Al₂O₃, and 3.8% LOI was subjected to reduction roasting followed by low intensity magnetic separation studies. The phase transformation of hematite into magnetite and fayalite due to reduction roasting was investigated using reflected microscope and X-ray diffraction (XRD) techniques. The effects of reduction variables such as reduction time (40?175 min), temperature (750?1000°C), and reductant dosage (3?11%) using activated charcoal were studied. The process was optimized by using central composite rotatable design (CCRD) and response surface methodology. Iron grade from 59?66% with recovery of 9.5?87% was achieved using CCRD experiments. Model equations were developed both for Fe grade and recovery and then optimized within the bounds of experimental conditions. The program predicted 63.3% Fe with 79% recovery with the following optimum conditions: temperature: 950°C, time: 53.04 min, and reductant: 3%.     

高梯度磁分离铬盐浸出浆液中的铬渣--II.实验研究

应用高梯度磁分离装置对铬盐浸出浆液中的铬渣进行了实验分离,测量了有效分离时间与流体粘度、磁场强度和流体流速之间的关系. 实验结果显示,当对理论模型作适当修正后,实验测量结果与模型计算结果基本一致.     

Analysis of Wet High-Intensity Magnetic Separation of Low-Grade Indian Iron Ore using Statistical Technique

The particle separation in a wet high-intensity magnetic separator depends on a number of variables. Applied magnetic field, particle size, and wash water rate play a vital role among them. Influences of these important variables were studied in detail following 3³ full factorial designs of experiments using a laboratory/pilot-scale wet high-intensity magnetic separator (Gaustec G-340 Minimag). Statistical analysis of the results indicated that the influence of all these variables are significant (95% confidence level) on the recovery of magnetics and the order of significance follows, particle size > magnetic field > wash water rate. The experimental results used to develop the regression models to predict yield and grade at unknown operating conditions in the study range.

Investigations carried out on a wet high-intensity magnetic separator using a low-grade iron ore sample containing 49.27% Fe shows that it is possible to upgrade to 62% Fe in the concentrate with poor yield values. A “tree” procedure (generally used to evaluate the flotation performance) was followed to evaluate maximum possible yield and grade by the magnetic separator. The “tree” procedure results provide useful information about the magnetic separation competence.     

纳米磁性高分子复合微球的制备及在分离工程中的应用

在总结国内外有关磁性高分子微球研究成果基础上，介绍纳米磁性高分子复合微球的制备方法，重点阐述核-壳式结构和三明治式结构纳米磁性高分子复合微球制备的最新研究进展，概述了磁性高分子复合微球在分离工程中的应用情况，并对磁性高分子微球的未来研究方向进行展望。     

Exploiting Size-Dependent Drag and Magnetic Forces for Size-Specific Separation of Magnetic Nanoparticles

Realizing the full potential of magnetic nanoparticles (MNPs) in nanomedicine requires the optimization of their physical and chemical properties. Elucidation of the effects of these properties on clinical diagnostic or therapeutic properties, however, requires the synthesis or purification of homogenous samples, which has proved to be difficult. While initial simulations indicated that size-selective separation could be achieved by flowing magnetic nanoparticles through a magnetic field, subsequent in vitro experiments were unable to reproduce the predicted results. Magnetic field-flow fractionation, however, was found to be an effective method for the separation of polydisperse suspensions of iron oxide nanoparticles with diameters greater than 20 nm. While similar methods have been used to separate magnetic nanoparticles before, no previous work has been done with magnetic nanoparticles between 20 and 200 nm. Both transmission electron microscopy (TEM) and dynamic light scattering (DLS) analysis were used to confirm the size of the MNPs. Further development of this work could lead to MNPs with the narrow size distributions necessary for their in vitro and in vivo optimization.     

Alumina-Iron Separation of High Alumina Iron Ore by Carbothermic Reduction and Magnetic Separation

The carbothermic reduction of high alumina iron ore in the absence/presence of sodium carbonate (Na₂CO₃) was carried out for alumina-iron separation by wet magnetic separation. Sodium carbonate is found to be capable of improving the separation of alumina and iron, as well as increasing the particle size of metallic iron significantly. When the high alumina ore briquettes were reduced at 1050°C for 80 min, the average particle size of metallic iron was approximately 100 μm in the presence of sodium carbonate, which is bigger than the size of 50 μm in the absence of sodium carbonate. Compared with the absence of sodium carbonate, the Al₂O₃ content of iron concentrate decreased from 4.33% to 1.29%, while the Al₂O₃ removal rate increased from 43.70% to 83.37% with the addition of 9% sodium carbonate. Experimental evidence showed that Na₂CO₃ reacted with Al₂O₃ and SiO₂ to form sodium silicate, aluminum silicate, and sodium aluminosilicate, and decreased the content of Fe in the slags, which improved the separation between the alumina and iron during the magnetic separation.     

Magnetic Carrier for Radionuclide Removal from Aqueous Wastes: Parameters Investigated in the Development of Nanoscale Magnetite Based Carbamoyl Methyl Phosphine Oxide

Abstract

A study on superparamagnetic magnetite polymer composite development was undertaken for application to magnetically assisted chemical separation. Tetramethyl ammonium hydroxide as an alternative to ammonia was used as a precipitation agent to obtain nanoscale magnetite particles. Investigation on stoichiometry control of Fe(III) and Fe(II) ions suggested a correlation between alkalinity and initial Fe(III): Fe(II) ratio for precipitation of magnetite. Studies on polymerization conditions suggested that polymers setting at ambient conditions enable retention of superparamagnetic property of substrate magnetite. Vaporization method for impregnation of solvent extractant CMPO, yielded product that had a high sorption capability for radionuclide europium as compared to wet impregnation method.     

酸敏感的缩醛键在药物载体中的应用

主要综述了缩醛键在药物载体中的作用和应用前景。     

Efficiency of High Gradient Magnetic Separation Applied to Micrometric Magnetic Particles

This article presents two prototypes of laboratory magnetic separators that generate high gradient magnetic fields. Such a field is created in a separation cell via steel wool. The efficiency of separators was tested on a water suspension containing weakly magnetic Fe₂O₃ nano/micro-particles, prepared in three size fractions in a size range of 60 nm – 10 μm. The separation process was evaluated via optical transmittance of the suspension before and after sequential separation processes. Repeated separations on the same sample exhibit an asymptotic trend that results in the conclusion that it is not possible to trap all solid content. According to the decrease of solid particles concentrations during cyclic separation we set the efficiency of the process. It is maximally 46% for fine fraction, 65% for medium fraction, and 40% for coarse fraction after infinity separation cycles.     

变频调速器在导焦车上的应用改造

变频器在导焦车上的应用使生产、节能二者兼顾 ,并达到了一个新的水平 ;通过改造 ,为变频器这一新型的调速设备在粉尘、湿度、温度都很高的环境中达到稳定运行提供了可借鉴的经验 ,保证了我厂自动化电气设备的稳定运行。     

湛江高岭土作FCC催化剂载体可行性试验研究

对湛江高岭土的物化性质进行分析测试,并对以湛江高岭土为载体制备的半合成催化剂进行评价。结果表明,湛江高岭土晶体结构以片状为主,粒度分布较为集中,化学组成与苏州高岭土基本相当;采用湛江高岭土为载体的催化剂,其质量指标和裂化性能与对比样相当,可以满足FCC催化剂质量指标的要求。