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.     

壳聚糖对微细粒蛇纹石的分散/絮凝作用

通过沉降试验、吸附量测试和Zeta电位测试,研究壳聚糖对微细粒蛇纹石的分散及絮凝作用,并考察其作用机理.结果表明:蛇纹石的沉降受pH值影响较大,在pH =9时沉降较快.壳聚糖对蛇纹石的絮凝作用受pH影响较大,在pH值为3时,壳聚糖溶解在水中,通过氢键作用吸附在蛇纹石表面,吸附量较低,对微细粒蛇纹石产生分散作用,使其沉降速度降低;pH值为9时,壳聚糖从溶液中析出,沉积在蛇纹石表面,吸附量较大,从而使微细粒蛇纹石形成较大的絮团,沉降速度较快并在底部形成体积较大的沉降体.当沉降体的pH值从9变为3时,沉积在蛇纹石表面的壳聚糖重新溶解,絮凝作用消失,蛇纹石絮团分散,蛇纹石颗粒在自身重力作用下继续沉降,使沉降体体积降低,含水量也降低.     

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 %。     

针铁矿法分离铬铁矿硫酸浸出液中Cr3+与Fe3+

采用针铁矿法分离铬铁矿硫酸浸出溶液中的Cr3+与Fe3+. 结果表明,以Fe2(SO4)3溶液中加入适量KOH后生成的Fe(OH)3为前驱体,在120℃的水热条件下保温8 h后可制备出晶体发育良好的针铁矿晶种. 将铬铁矿硫酸浸出液的Fe3+浓度稀释至1 g/L以下并加入针铁矿晶种,在pH=2.5、温度90℃条件下保温4 h后,Fe3+以针铁矿晶体沉淀析出,能实现铁与铬的分离,除铁率为97%,铬损失率为33%.     

Magnetic particles for sugar separation from sulphuric acid solution generated during nano‐crystalline cellulose production

Nano‐crystalline cellulose (NCC) is a renewable material having different applications ranging from drug delivery to a reinforcing filling agent in polymer synthesis. Concentrated sulphuric acid is used to hydrolyze cellulosic biomass to obtain NCC. Manufacturers are keen to reuse the diluted acid solution left after the process. However, the presence of mono and oligosaccharides makes it unsuitable for repeated use. About 99 % of these compounds have been successfully separated from the acid solution by employing NaOH‐treated magnetic particles developed during this investigation. It has been observed that by NaOH treatment, zeta potential of the magnetic particles could be increased from +11 mV to +37.5 mV; correspondingly, sugar removal efficiency was increased from 23.04 % to more than 99 %. Thus a direct correlation between the change in zeta potential of the particles and sugar separation efficiency has been observed.     

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。     

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...     

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.     

The Simple Method of Preparation of Highly Carboxylated Bacterial Cellulose with Ni- and Mg-Ferrite-Based Versatile Magnetic Carrier for Enzyme Immobilization

The bacterial cellulose (BC) is a versatile biopolymer of microbial origin characterized by high purity and unusual water and material properties. However, the native BC contains a low number of functional groups, which significantly limits its further application. The main goal of its effective modification is to use methods that allow the unusual properties of BC to be retained and the desired functional group to be efficiently introduced. In the present study, the new magnetic carrier based on functionalized citric acid (CA) bacterial cellulose was developed and tested to support critical industrial enzymes such as lipase B from Candida antarctica and phospholipase A from Aspergillus oryzae. The applied method allowed BC to be effectively modified by citric acid and a sufficient number of carboxylic groups to be introduced, up to 3.6 mmol of COOH per gram of dry mass of the prepared carrier. The DSC and TGA analyses revealed carrier stability at operational temperatures in the range of 20 °C to 100 °C and substantially influenced the amount of the introduced carboxyl groups on carrier properties. Both enzymes’ immobilization significantly improves their thermal stability at 60 °C without a significant thermal and pH optima effect. The analyzed enzymes showed good operational stability with a significant residual activity after ten cycles of repeated uses. The new magnetic carrier based on highly carboxylated bacterial cellulose has a high application capability as matrix for immobilization the various enzymes of industrial interest.     

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.     

RH炉浸渍管用镁铬砖的损毁行为分析

利用化学分析、X射线衍射仪、光学显微镜、扫描电镜及压汞仪等方法对武钢RH精炼炉浸渍管用后镁铬残砖进行了分析,旨在找出镁铬砖的损毁行为.结果表明:残砖粘渣且存有裂纹.残砖渗透、侵蚀层主要有低熔点的钙铝黄长石和铁及其氧化物;在渗透、侵蚀层与原砖层之间存在由FeO和镁铝尖晶石组成的约40 μm厚的致密过度层.镁铬砖的损毁主要包括2部分,前期主要是砖体气孔率高、气孔直径大造成的熔渣及钢水渗透,后期是渗透的熔渣及钢水加剧砖体的溶蚀及热剥落;因此改善镁铬砖的气孔特性将会成为减缓其损毁的重要途径.     

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%.     

菱铁矿磁化焙烧与磁选分离制备铁精矿

对国内某地菱铁矿进行无还原剂全粒级磁化焙烧-磁选研究. 结果表明,菱铁矿在无还原剂条件下于800℃焙烧15 min,所得焙烧矿在磨矿粒度小于0.074 mm占90%、磁场强度0.10 T条件下磁选,得到铁品位63.15%、铁回收率92.52%的铁精矿. 磁选精矿中的锰、镁和部分钙与铁元素以类质同像共存.     

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.     

鲕状赤铁矿磁化焙烧-磁选过程研究

以鄂西某鲕状赤铁矿为研究对象,考察了焙烧时间对其磁化焙烧与磁选过程、相态转化及焙烧变化规律的影响. 结果表明,含铁鲕粒多数由赤铁矿内核与致密同心外壳及其中间夹带的脉石矿物构成;含铁(TFe) 49.02%的鲕状赤铁矿在800℃下磁化焙烧60 min后再用磁选管分选,获得含铁56.34%、铁回收率为88.05%的较好结果,焙烧时间对磁化焙烧影响显著. 磁化焙烧过程仅改变铁相,而鲕粒结构未变;磁化还原由表及里受扩散作用控制,还原程度随焙烧时间延长逐步增加. 800℃下焙烧时间小于30 min时,极少过还原生成FeO,之后则有少量FeO生成,较少形成Fe2SiO4;含磷与含硅矿物均有相变,但转变时间不同.     

磁性纳米颗粒-微波辐射对稠油O/W乳状液的协同破乳

首先分析了微波辐射功率和辐射时间对磁性纳米粒子协同破乳的影响规律,在此基础上,利用生物显微镜、接触角测量仪、zeta电位分析仪等分别测量了微波作用前后油滴的分布以及磁性纳米粒子的润湿性和带电性,从而揭示了微波和磁性纳米粒子的协同破乳机理。实验结果表明：磁性纳米粒子作用下,微波辐射参数过高或者过低都会对磁性纳米粒子破乳产生抑制作用,只有在最优辐射参数范围内,微波才会促进磁性纳米粒子的破乳,且当纳米Ni浓度为150mg/L,微波辐射参数为400W、30s时,乳状液的分水率达到最高值102.56%,而在相同微波辐射参数下,Co₃O₄浓度为125mg/L,乳状液的分水率达到最大值106.06%。该工作为磁性纳米颗粒-微波辐射协同破乳技术的发展提供试验和理论依据。