Oil Spill Remediation Using Magnetic Separation

Magnetic separation technology was applied to remove dispersants and crude oil from water with magnetite and maghemite. Maghemite exhibited rather constant removal efficiency for dispersants regardless of surfactant types, while magnetite exhibited higher removal efficiency for anionic surfactant, and the efficiency was higher in deionized water than in salty water that contains more ions. Sorption of the dispersants to magnetite can be explained with electrostatic attraction, while binding of the dispersants to maghemite can be described with electrostatic attraction as well as with the structural characteristics that provide high sorption capacity. The result from a water bath experiment, which was to test the collection efficiency of magnetic particles from water, indicated that the recovery efficiency of magnetic particles was nearly 100% after the dispersants had been sorbed. More than 80% of the oil was collected when the magnetite-to-oil ratio was more than 0.89, while the same percentage of oil was harvested when the maghemite-to-oil ratio was more than 0.46 in the oil removal experiment. Sorption of crude oil to magnetic particles can be explained with the fine particle–oil flocculation, which is associated with an electrostatic attraction between the magnetic particles with charged surface and polar compounds in the crude oil.     

超细铁粉的制备及其对硝酸盐的降解

分别采用液相还原改性法和微乳液法制备超细铁颗粒,用乙醇-水体系制备镍包覆铁颗粒的Fe/Ni双金属颗粒,用来进行硝酸盐的降解实验,并用扫描电镜(SEM)和X射线衍射(XRD)分析超细粉末的物相结构及形貌.结果表明:通过液相还原改性法制备的超细铁粉,颗粒形状不规则,颗粒大小在0.2～0.3 μm之间;而用乙醇-水体系制备的铁/镍粉颗粒为等轴晶粒,颗粒大小也在0.2～0.3 μm之间;加入PEG-6000可改善液相改性法和醇-水法制备的铁粉的分散性.微乳液法制备的铁粉为球形颗粒,存在较明显的团聚现象,颗粒大小在0.5～ 1μm之间.在相同条件下,不同方法制备的超细铁粉降解硝酸盐的能力由高到低依次为:微乳液法制备的铁粉＞乙醇-水体系法制备的Fe/Ni双金属粉＞液相还原改性制备的铁粉＞不加PEG的乙醇-水体系制备的铁粉.     

Some Factors Influencing the Sintering Behaviour of Austenitic Stainless Steel Powders

Abstract

Densification studies of sintered stainless steel powder blends have shown that the introduction of delta-ferrite into the micro structure increases substantially the sintering rate of the compact. Model experiments, in which spherical particles of a 316 powder were sintered on several different base plates including iron, 18Cr–12Ni stainless steel, iron–12% nickel, have been carried out to provide more detailed information. Quantitative observations have been made on the rate of neck growth and on the compositional gradients which develop between particle and plate. It has been found that the sintering rates were very sensitive to the composition of the base plate and to the presence of austenite/ferrite interfaces. Micro-examination and the use of electron probe microanalysis indicate that interdiffusion of elements between particles and plates is by both surface and volume diffusion.     

微细铁颗粒的单体解离特性和选择性回收工艺

研究了直接还原熟料中微细铁颗粒的赋存形式和选择性回收工艺.发现尾渣中铁的赋存形态主要为微细粒的单质铁;直接还原熟料中小于5μm的细连生体和铁颗粒很难通过磁选回收,但大于10μm的粗铁颗粒可以回收.为了兼顾粉末铁的品位与回收率,需要对不同赋存状态的铁颗粒进行选择性回收.提高粗连生体的单体解离度,有针对性地回收其中的铁颗粒,是提高粉末铁回收指标的关键.提高磁选场强可提高粉末铁回收率,但降低粉末铁品质.利用正交试验对工艺参数进行了优化,在优化条件下粉末铁中TFe质量分数和铁回收率分别为92.91%和92.03%.      

EPMA drives collaborative development projects

Abstract

An analysis has been performed on the selective removal of particles from the edges and thin lands on green iron powder compacts. The voids created as a result of this ‘picking’ are believed to be due to large (+ 125 μm (+ 120 mesh)) particles in the iron powder mix. Microscopic examinations indicated that in all cases picking occurred within isolated regions of large pore and particle size. Two possible independent causes for this problem have been advanced: segregation of large particles within the feed shoe during die filling; and an uneven load distribution across the face of a part due to the presence of tooling impressions on the upper punch. A series of follow up tests showed no change in the relative position of the large pore size region with upper punch orientation. Therefore, by deduction, particle segregation is advanced as the main cause of the observed picking. Suggestions are presented to alleviate this problem. PM/0495     

高含钒粗四氯化钛有机物预处理除钒工艺研究

攀钢高炉渣提钛工艺生产出的粗四氯化钛含钒量高(4.9‰),不能直接用攀钢现有的铝粉除钒工艺。为解决四氯化钛含钒高的问题,提出了在铝粉除钒前采用有机物预处理除钒的工艺,并对影响除钒效果的主要工艺参数,如有机物种类及用量、温度和时间等进行了优化。结果表明,采用3%矿物油在45℃下预处理30 min可以将粗四氯化钛中的钒降至1.667‰。且预处理产生的除钒泥浆具有较好的沉降性能,分离泥浆后得到的四氯化钛满足铝粉除钒对原料的要求。另外,蒸干除钒泥浆所得的尾渣中含有大量的钒(8.06%),具有较高的回收利用价值。     

610 MPa级大型石油储罐用高强度钢板的开发

 对不同成分试验钢采用了TMCP和离线调质处理2种工艺制度生产储油罐用高强度钢,并对钢板进行常规拉伸实验和冲击实验,分析其组织结构和断口形貌。最终确定大型原油储罐用高强度钢板的化学成分,在此基础上建议采用TMCP和离线调质处理2种工艺来生产大型原油储罐用高强度钢板。     

含锌除尘灰锌铁分离研究

摘要：含锌除尘灰是钢铁厂重要的固体废弃物,属于危废,为了探索妥善解决该种危废的方法,模拟回转窑工艺对国内某钢厂含锌除尘灰进行焙烧 磁选锌铁分离研究,研究不同焙烧温度、时间以及不同内配C含量对焙烧矿金属化率、脱锌率以及对磁选后精矿铁品位、Fe回收率的影响。结果表明,在C质量分数为12%、焙烧温度1100℃、焙烧时间60min的条件下,得到铁品位53.45%、金属化率91.95%、脱锌率99.05%的焙烧物料,挥发物中ZnO质量分数高达95.04%。焙烧物料经过磨矿磁选后可得到铁品位91.30%,Fe回收率82.37%的金属铁粉。     

Selection of Alloying Method to Produce Iron-Based Powder

There are different methods to produce low-alloyed iron-based powders. The properties of such powders depend on the method of alloying as well as on the characteristics of the basic grade of iron powder. A comparative experimental study to estimate the influence of the basic iron powders on low alloyed powder properties has been conducted. The method of co-reduction of powdered oxides that contain alloying elements and selected iron powder grades has been selected. Chemical and mass spectrometer analysis has shown satisfactory alloying element distribution. Tensile strength test of the sintered parts has shown that the best results are obtained for specimens produced from low alloyed powder of Indian “Blue Dus” concentrate as the basic iron powder grade. __________ Translated from Poroshkovaya Metallurgiya, Nos. 5–6(443), pp. 8–3, May–June, 2005.     

巴润精矿配比对球团矿强度的影响

 为了充分发挥巴润铁精矿(白云鄂博西矿)含铁品位高、粒度分布集中、成球性能优异的特点,同时抑制其K₂O、Na₂O和F含量较高的弱点,研究了如何通过其与有害元素含量较低的区内矿合理搭配,在保证氧化球团成品矿强度的基础上,提高巴润矿的利用率。研究过程中,采用FactSage7.3热力学软件计算、氧化焙烧、抗压强度检测、化学成分检测、矿相分析、SEM-EDS分析等试验研究手段,对不同巴润铁精矿配比下成品球强度的影响因素进行了分析。研究结果表明,区内铁精矿比巴润铁精矿的粒度范围宽,两者平均粒度分别为53.21 μm和32.01 μm;区内矿铁精矿小于0.043 mm(<300目)的矿粉颗粒比例为78.65%,而巴润铁精矿粉所占比例为84.70%。巴润矿配比为40%的成品球的强度最高,为4 602.2 N/P。热力学计算表明,随着巴润矿配比增加,成品球中渣相量增加;氧化焙烧冷却过程中,40%巴润矿配比的成品球渣相析出物以辉石和石英为主,而100%巴润铁精矿成品球渣相析出物则以钙铁橄榄石为主。矿相结构上,随着巴润铁精矿配比增加,赤铁矿连晶效果下降,但40%配比时渣相分布均匀,起到了较好的黏结相的作用。100%巴润矿成品球中由于MgO质量分数达到1.05%,所形成的含镁磁铁矿颗粒连晶作用较差,这是造成其抗压强度较低的原因之一。     

Microstructure and tensile properties of compacted,mechanically alloyed,nanocrystalline Fe-AI

Data on mechanical properties of nanocrystalline materials have been limited, due in part to the difficulty in producing consolidated nanocrystalline materials of sufficient quantity for characterization and evaluation. A second problem is consolidation and retention of the nanostructure. A vacuum hot-pressing consolidation program has been developed to produce full-dense compacts from attrition milled, mechanically alloyed, nanograin micron-size particles of Fe-2 wt pet Al powder. The resulting compacts were of sufficient size to allow evaluation of microstructure, density, hardness, and tensile properties. The compacted microstructure was a composite of pure iron submicrograins and Fe-A1 nanograin clusters. Tensile strength was found to be proportional to the sample’s density squared. For full-dense compacts, tensile strength of nanocrystalline compacts approaching 1 GPa was obtained.     

陕西某次生岩型红柱石矿的生产流程及产品品质

次生石英型红柱石矿,矿石呈浅红色,矿物颗粒细小,分布均匀,红柱石含量高,实际入选矿石品位多在33%以上,矿石中含有极少量金红石、褐铁矿、黄铁矿等,是精矿中TiO_2和Fe_2O_3的主要来源,通过细磨磁选可以减少精矿中Fe_2O_3含量。实际生产流程为磁选重选联合流程,流程简单,不添加任何化学药剂,也不需要尾矿库,磁机分离的铁矿物和尾矿混在一起都是生产水泥的好原料。生产的产品分粒料和粉料两大类六个品种,以粉料为主,通过多次反复除铁,大大降低了粉料中铁的含量,生产的粉料质量基本符合行业标准。     

转炉炉尘铁粉的改性研究

采用腐蚀球磨法＋二次氢还原工艺技术将转炉炉尘铁粉改性为附加值高的粉末冶金用铁粉。通过扫描电镜、原子吸收光谱仪、碳硫直读程控分析仪、化学分析法等对改性前后铁粉的理化指标及形貌进行表征。研究了各种直径磨球配比、料球比、腐蚀介质、搅拌球磨时间及氢还原过程对改性铁粉形貌、纯度、松装密度的影响，得到改性的较佳工艺条件。结果为：炉尘铁粉细化，表面粗糙，铁粉纯度可达到99.47％，松装密度可在3.6—2．3g／cm^3范围内调整。     

Surface Modification of Highly Dispersed Powders of Iron and Its Composites with Platinum and Silver by Polyvinylpyrrolidone

Surface modification of particles of fine iron powder and its composites with platinum and silver is shown to be feasible if polyvinylpyrrolidone is used. Such surface properties of powder particles as physical adsorption and hydrophilic nature made it possible to develop composites for a variety of applications, in particular for medicine (treatment of purulent-inflammatory diseases, wounds, ulcers, etc.).     

A new generation of sprayed iron powder for complex parts

The basic parameters have been developed for the production of sprayed iron power of compressive strength approaching that of high-quality reduced powder. The properties of such powder are due to the chemical purity and rounded shape of the particles, as well as the developed surface microrelief. At the experimental facility at Bardin Central Scientific-Research Institute of Ferrous Metallurgy, a laboratory batch of iron and partially alloyed powder has been produced from powder composites based on air-sprayed powder and activating iron-bearing additives, by simulating OOO SSM-Tyazhmash industrial equipment.     

Effectiveness of reducing agents during sintering of Cr-prealloyed PM steels

Abstract

Development of strong inter-particle necks requires successful removal of surface oxides, present on the powder particles, during the initial stages of sintering. In the case of water-atomised powder prealloyed with chromium, the surface oxide consists mainly of an iron oxide layer with some more stable fine particulate oxides. The formation of sufficiently strong inter-particle necks requires as a minimum full removal of the iron surface oxide layer. This can be achieved by gaseous reducing agents (e.g. H₂, CO or a mixture of both) or by carbon, typically admixed in the form of graphite. The reducing power of various sintering atmospheres (active gas content ≤10 vol.-%) and their combined effect with graphite has been investigated by a thermal analysis technique. Results indicate that a combination of a dry hydrogen-containing atmosphere and fine graphite allows successful sintering of chromium alloyed PM steels.     

利用冶金含铁粉尘制备超细铁粉的试验

针对冶金含铁粉尘杂质含量较高、原始颗粒细小容易污染环境等问题，采取除杂提纯分离- 还原两步法制备超细铁粉。通过湿法反应、磁选、浮选等除杂提纯工序，含铁粉尘中SiO2质量分数降低到0.12%，CaO、MgO质量分数同时得到不同程度的下降。分离杂质后的含铁粉尘还原试验结果表明，在H2气氛、还原温度为750 ℃、保温1 h的条件下，得到的超细铁粉TFe质量分数达到99.27%，微观形貌观测颗粒平均粒径约为1 μm，比表面积为2.495 m2/g。经过压制成型及烧结试验，表明得到的超细铁粉易于压制成型，颗粒烧结反应活性好，压制的成型坯体烧结温度为850～900 ℃，明显优于常规还原铁粉。     

炼钢技术的发展历程和未来展望(Ⅱ)——炼钢的未来展望

首先讨论了科技进步为推动力的铁水预处理技术、转炉冶炼技术、炉外精炼技术和连铸技术的进步。传统的KR铁水预处理技术采用了载气枪喷入脱硫剂粒子之后,增大了脱硫剂粒子进入铁液的深度并降低了粒子之间聚合的发生,既节省了脱硫剂的使用又提高了脱硫的效率;使用铬矿粉为原料通过转炉冶炼不锈钢过程中,采用副枪燃气燃烧送料技术,既实现了温度达标,也降低了铬的氧化烧损;钢液炉外精炼技术是在吹氩技术、真空技术和电磁技术等多项技术支撑下逐渐发展的;连铸技术也是在电磁技术、机械压下、数字技术的支撑下实现了无缺陷连铸坯的制造和近终形薄带连铸的产业化。然后,从钢洁净度的极限、未来的炼钢工艺展望和连续炼钢工艺3个方面讨论了炼钢技术的未来。目前钢中氧、碳、氮、磷、硫、氢6大元素总和已经能达到0.006 0%以下,特别是钢中总氧质量分数可以达到0.000 5%以下,但是关于钢中金属杂质元素包括锌、锡、铅、锑、铋、砷等去除的研究还需要加强;在信息化和自动化技术充分发展的条件下,无喷溅、无人工操作、无人工维护的“全智能转炉”是有可能实现的;连铸的大数据技术、软件技术和信息物理系统已经在一些先进钢厂得到应用;欧盟已经开始尝试铁矿...     

Effect of structure of a magnetoabrasive material on its life in the polishing of metals

Conclusions The mechanism by which the particles of a magnetoabrasive powder disintegrate depends on their structure and determines the service performance of the material. The disintegra tion of the particles of the sintered Zh15KT material involves the plucking out of the abrasive component and its removal from the machining space. Under these conditions, the fall in the fraction of the abrasive component in the polishing powder and the resultant decrease of the mechanical wedging forces lower the pressure which the Zh15KT particles exert on the work surface and have an adverse effect on the operating performance of the powder as a whole. The particles of a cast material cease to be effective mainly through attrition. As their nonporous matrices possess high hardness and strength and contact be tween the magnetic matrices and the abrasive over their interfaces is continuous, the service life of a cast powder is much (more than twice) longer than that of the sintered Zh15KT powder agglomerates, in which, because of their high porosity, contact on the interfaces between the iron and titanium carbide particles is discontinuous.Translated from Poroshkovaya Metallurgiya, No. 3(231), pp. 98–101, March, 1982.     

The history of Distaloy

Abstract

The low alloy steel powder Distaloy, is today widely used in applications demanding high strength and wear resistance. Its basic properties and composition were designed half a century ago in the USA. The advantage lay in the fact that it was a partial prealloy, i.e. the alloying elements – copper, nickel and molybdenum – were bonded in particulate form to the basic iron particles, thus avoiding impairment of the compressibility. By balancing the contents of nickel and copper it was possible to minimize dimensional change on sintering. Bonding the alloy particles to the iron particles minimised segregation and also contributed to dimensional stability. Carbon was added conventionally as fine graphite. However, the new powder, marketed as Ancoloy, did not take off in North America, due to the lack of suitable applications, the cost of the alloying elements and – above all – the poor compressibility and high oxygen content of the iron powder then available. The high, variable oxygen content made it impossible to control the carbon content with the precision necessary to achieve the desired strength and hardness.

In the 1960s, demand for high strength precision parts emerged in the European car industry, initially at Citroen, which pioneered increased use of PM parts in European cars. The component was (and still is) the synchronising hub used in manual transmissions. Höganäs had in the mid-1960s developed a sponge iron powder with much higher compressibility, and this was taken as a raw material for an improved grade, later to be called Distaloy SA. This new powder had improved compressibility and very low oxygen and carbon contents, which made it possible to make the high strength precision parts that the car industry required. Distaloy was immediately accepted and used, first in the French car industry, then elsewhere in Europe and subsequently also in Japan. Some years later, when high compressibility atomised powder became available, the same basic technique was applied to these, to produce the Distaloy A grades, which now are most popular. Höganäs continues to improve and refine the production techniques and to come up with compositions for new applications.

The properties and the metallurgy of Distaloy-based materials have been thoroughly studied by metallurgists at Höganäs and at PM laboratories throughout the world, and new results are still being reported with respect to both applications and fundamental properties. A parameter of great relevance is of course the cost of raw materials and much effort is going into finding more cost effective ways of achieving the desired results.