Oxidation and Induration Characteristics of Pellets Made from Western Australian Ultrafine Magnetite Concentrates and Its Utilization Strategy

Western Australian magnetite concentrates normally have ultrafine granularity and much higher specific surface areas than Chinese magnetite concentrates owing to the significant pre-grinding and beneficiation for saleable iron grade.Such characteristics will inevitably affect the subsequent pelletization process.However,very few investigations have been done before.Thus,the oxidation and induration characteristics of pellet made from a Western Australian ultrafine magnetite concentrate were revealed by conducting routine preheating-roasting tests in an electric tube furnace and investigating the microstructure of fired pellets under an optical microscope in comparison with that of pellets made from typical Chinese magnetite concentrate.The liquidus regions of CaO-SiO_2-Fe_2O_3 and CaOSiO_2-Al_2O_3 ternary systems in air at various temperatures were calculated by FactSage software to explain the importance of liquid phase in the consolidation of fired pellets.The results show that pellet made from ultrafine magnetite concentrate possesses better oxidability and preheating performance than that made from Chinese magnetite concentrate.However,it has inferior roasting performance,usually requiring conditions of roasting at 1 280℃ for at least 30 min to acquire sufficiently high compressive strength,which are attributed to higher temperature sensitivity caused by its smaller particle size and less formation of liquid phase because of low impurities like CaO and Al_2O_3 in raw materials.Correspondingly,its roasting performance can be significantly improved by blending with Chinese magnetite concentrates or increasing the pellet basicity(wCaO/wSiO_2).By comprehensive evaluation,blending with Chinese iron ore concentrates is an appropriate way to utilize Western Australia ultrafine magnetite concentrates.     

Study on Direct Reduction Characteristics of Iron Ore Coal Mixed Pellets

Ｉｒｏｎｏｒｅｃｏａｌｍｉｘｅｄｐｅｌｌｅｔｓａｒｅｃａｐａｂｌｅｏｆｑｕｉｃｋｌｙｓｅｌｆ ｒｅｄｕｃｔｉｏｎ .Ｉｎｔｈｅｙｅａｒｓｏｆｓｉｘｔｉｅｓ ,ｔｈｅＩｎｍｅｔｃｏｐｒｏｃｅｓｓａｎｄＭｉｄｒｅｘＦａｓｔｍｅｔｐｒｏｃｅｓｓｆｏｒｍａｋｉｎｇｃｏａｌｍｉｘｅｄｐｅｌｌｅｔｓｔｏｄｅａｌｗｉｔｈｔｈｅｓｅｃｏｎｄａｒｙｄｕｓｔｉｎｉｒｏｎａｎｄｓｔｅｅｌｐｌａｎｔｏｒｔｏｐｒｏｄｕｃｅＤＲＩ[1- 3] ｗｅｒｅｄｅｖｅｌ ｏｐｅｄ .Ｒｅｃｅｎｔｌｙ ,ａｌｏｔｏｆｂａｓｉｃｒｅｓｅａｒｃｈｅｓｏ…     

链篦机-回转窑铁矿氧化球团焙烧过程的分析

为了降低链-回-环系统球团矿焙烧过程的能耗,对某工业装置进行了平衡测试和分析,得到了流图。分析表明,传热不可逆损和燃烧不可逆损是系统损的主要部分。建立了气体质流量、床层空隙率、床高、球团直径、烟气中氧含量等运行参数与损的关系。结果表明,适当减小气体质流量、床高和球团直径,增大床层空隙率,可以减小损。在其它条件不变的情况下,当烟气中二氧化碳浓度为1.0%～9.0%,将空气消耗系数控制在1.6～2.0,可使损最小。     

Iron Ore Sintering: Raw Materials and Granulation

Sintering is an agglomeration process that fuses iron ore fines, fluxes, recycled products, slag-forming elements and coke. The purpose of sintering is to obtain a product with suitable composition, quality and granulometry to be used as burden material in the blast furnace. This process is widely studied and researched in the iron and steelmaking industry. In this context, achieving an adequate sintered product depends on the adequate raw materials supply and the previous stage to the sintering process, granulation. For that reason, in this paper, the granulation process is studied as a consequence of being the source of pre-agglomerated materials for the subsequent sintering process. Thus, the main tests used to the determination of the properties are reviewed as well as the main granulation processes.     

配矿对改善昆钢球团质量的影响

在综合考虑昆钢10种单一铁精矿成球性能以及球团预热、焙烧性能的互补性、铁精矿TFe品位、原料成本、矿石供应量等因素影响的前提下,对10种配矿方案的造球性能以及球团预热、焙烧性能进行了研究。结果表明,与昆钢生产使用的配矿结构相比,通过对铁精矿进行优化配矿,采用C矿：E矿：H矿=30％：40％：30％的配矿结构,能最大幅度地降低膨润土用量,提高生球质量和球团矿强度,保障球团有效TFe品位,降低原料成本。     

Brazilian Iron Ore and Production of Pellets

Brazil is the second-largest producer of iron ore in the world. Brazilian richer superficial deposits are composed of brittle material with fine texture and significant amounts of fines are generated during mining and transport. Another type of ore found in this country is the itabirites that have lower iron contents. Beneficiation and concentration steps are required to prepare these materials for the pelletizing process. A general view of Brazilian types of iron ores, mines, and mining companies is given in this work. Special attention is given to pelletizing and the influence of mineralogical characteristics of different ores on the production and final properties of iron ore pellets.     

煤种对含煤球团还原速度的影响

研究了在１２２３￣１４７３Ｋ的氮气氛中３种不同挥发分煤粉的粒度、铁精矿粉粒度、温度及碳－氧摩尔比对含煤球团还原速度的影响。发现降低煤粉或铁精矿粉粒度，提高温度或碳－氧摩尔比可提高含煤球团的还原速度，且这４种因素对还原速度的影响程度随煤种挥发分的降低而增大。分别采用以碳气化反应、气相内扩散、界面反应为控制环节而得出的表达含煤球团反应过程的速度方程处理本研究数据，发现３种速度方程（４种表达形式）均能较     

Pellets Prepared with Mechanically Activated Iron Ore

This work analyses pellets prepared with iron ore that has been mechanically activated by high energy ball milling. Pellet feed iron ore was submitted to high‐energy ball milling for 60 minutes, and the resulting material was analysed through measurements of particle size and specific surface area, as well as X‐ray diffraction. Pellets were prepared from this material. The pellets were heated at temperatures ranging from 1000 to 1250°C in a muffle furnace, and submitted to the maximum temperature during 10‐12 minutes. The samples were then tested regarding crushing strength, densification and porosity, and were examined in a scanning electronic microscope. The results were compared to those obtained with similar samples made from non‐milled pellet feed. It has been shown that through high‐energy ball milling of iron ore it is possible to achieve pellets presenting high densification and compressive strength at firing temperatures lower than the usual ones.     

Cold Bonding of Iron Ore Concentrate Pellets

Iron ore concentrate pellets are traditionally hardened at high temperatures in horizontal grates and grate-kiln furnaces. However, heat induration requires tremendous quantities of energy to produce high-quality pellets, and is consequently expensive. Cold bonding is a low-temperature alternative to heat induration. Pellets can be cold bonded using lime, cement, sponge iron powder, and organic materials such as starch and flour. Cold bonding consumes less energy than heat induration, and has found favor for bonding self-reducing pellets and for refractory ores that are difficult to heat-treat. Herein, we review the principal cold bonding methods and their fundamentals.     

高铝低硅块矿工艺矿物学及冶金性能研究

研究了一种产自非洲的高铝低硅块矿工艺矿物学和冶金性能,并与几种国内外典型块矿的冶金性能进行对比.结果表明:非洲块矿是一种由赤铁矿、针铁矿和三水铝石等矿物组成的高铝低硅高铁矿石,微孔发达,Al2O3含量较高.而就其含铁品位及脉石含量而言,要明显高于国内天然块矿,但低于其它进口块矿.非洲块矿具有良好的还原性(RI80!)和低温还原粉化性能(RDI+3.15 mm达86.69!)、较强的抗热爆裂性能(DI-6.3mm1!)及与其它进口块矿相近的高温软熔特性,可与国内低铝块矿、烧结矿、球团矿搭配使用来满足高炉渣型的要求,进而控制炼铁成本、扩大原料来源.     

Effect of CaO and CaCO3 on Reduction Rate of Iron Ore Pellets Containing Carbon

Ｔｈｅｃａｒｂｏｎｇａｓｉｆｉｃａｔｉｏｎｈａｓａｇｒｅａｔｅｆｆｅｃｔｏｎｒｅ ｄｕｃｔｉｏｎｂｅｈａｖｉｏｒｏｆｉｒｏｎｏｒｅｐｅｌｌｅｔｓｃｏｎｔａｉｎｉｎｇｃａｒｂｏｎ ,ｅｓｐｅｃｉａｌｌｙｉｎｎｅｕｔｒａｌａｔｍｏｓｐｈｅｒｅ .Ｇｅｎｅｒａｌｓｐｅａｋｉｎｇ ,ａｄｄｉｎｇａｎｙａｄｄｉｔｉｖｅｓ ,ｗｈｉｃｈｃａｎｐｒｏｍｏｔｅｃａｒｂｏｎｇａｓｉ ｆｉｃａｔｉｏｎｒｅａｃｔｉｏｎ ,ｃａｎｅｎｈａｎｃｅｔｈｅｒｅｄｕｃｔｉｏｎｒａｔｅｏｆｉｒｏｎｏｒｅｐｅｌｌｅｔｓｃｏｎｔａｉｎｉｎｇｃａ…     

高结晶水锰矿粉制备高性能球团研究

 以进口高结晶水含量的锰矿粉为原料,经过开路二次高压辊磨预处理,模拟链篦机 回转窑工艺制备高强度高品位氧化球团。结果表明,对于品位为w(Mn)= 43.09%、 铁的质量分数为6.49%、烧损14.64%及0.5~8 mm占77.81%的锰矿粉,经过高压辊磨预处理,<0.045 mm占59.18%,比表面积高达2653 cm2/g,在添加2.0%的膨润土、造球时间7 min、生球水分（16±0.5）%的条件下,取得了生球落下强度23.1次/0.5m、抗压强度10.20 N/个的良好指标;球团在预热温度1050 ℃、预热时间10 min、焙烧温度1340 ℃、焙烧时间15 min的条件下在管炉内焙烧固结,成品球团矿抗压强度可达到2711 N/个。成品球团矿中w(Mn)= 49.11%,S、P等有害元素含量较低,是优质的高炉或电炉原料。     

含碳球团生产珠铁的试验研究

 采用以铁精粉、煤粉和石灰石为主要原料制成含碳球团,在1573、1623、1673K下进行了不同加热时间的还原试验研究,并分析计算了炉料带入硫的去向。试验结果表明：在温度为1673K、12min时,渣铁已经能够很好的分离。所得珠铁中碳、硫的质量分数分别为3.53%和0.17%,珠铁的内部组织结构主要由珠光体和渗碳体组成。渣中以硅酸钙(CaSiO3)和硅酸二钙(Ca2SiO4)为主,含有少量的钙镁橄榄石(CaMgSiO4)和玻璃体。计算得知：炉料带入的硫中24.61%进入渣、61.91%进入铁、13.48%进入空气。     

Reduction Characteristics and Kinetics of Bayanobo Complex Iron Ore Carbon Bearing Pellets

 The kinetics of isothermal reduction of the carbon bearing pellets, which were mainly composed of Bayanobo complex iron ore and pulverized coal, was investigated by thermogravimetry at the temperature of 1273-1673 K. The effects of xC/xO and the atmospheres on the extent of reduction also were investigated. The results indicate that the fractional reaction increased proportionally with temperature increasing and heating temperature is the significant influence factor to the reaction of carbon bearing pellets. The optimum xC/xO is 1. 2 and the effect of atmosphere on the reduction of iron oxides is almost negligible. The results can be interpreted that the reaction was initially controlled by a mixed controlled mechanism of carbon gasification and interface chemical reaction, and in the later stage, interface chemical reaction became the rate-controlling step. Apparent activation energy values of reduction at different levels of fractional reaction were calculated. Before F (fraction of reaction)=0. 5, the apparent activation energy ranges from 66. 39 to 75. 64 kJ/mol, while after F=0. 5, the apparent activation energy is 80. 98 to 85. 37 kJ/mol.     

Mechanisms of Swelling of Iron Ore Oxidized Pellets in High Reduction Potential Atmosphere

The influences of the time,temperature and atmosphere on the reduction swelling of oxidized pellets were investigated by single factor experiments.The mechanisms of reduction swelling of oxidized pellets were analyzed and investigated by SEM(scanning electron microscopy)and XRD(X-ray diffractometer)analysis.The results show that the change rules of reduction swelling index of oxidized pellets in different reduction atmospheres are very similar.With the increase of reduction time,the reduction swelling index moves up firstly and then down.When the reduction temperature is above 900℃,α-quartz turns intoα-tridymite,and the transition generates additional volume expansion effect.The reduction swelling index changes faster in H2 atmosphere than in CO atmosphere.Increasing H2 content in the reduction atmosphere is useful to decrease the reduction swelling index,but it is also easy to cause oxidized pellets cracking.     

Use of Iron Ore Fines in Cold-Bonded Self-Reducing Composite Pellets

The feasibility of producing direct reduced iron from cold-bonded, self-reducing composite pellets, constituted from beneficiated iron ore slime, coke, and different binders (dextrin, bentonite, calcium lignosulfonate, and carboxymethyl-cellulose [CMC]) was studied. This was done using a design of experiments approach. It was found that as-received beneficiated iron ore slime is suitable as a raw material for the production of self-reducing composite pellets with carboxymethylcellulose as the most suitable binder. Dry strengths in excess of 300 N/pellet were attained by curing the pellets under ambient conditions. The composite pellets reduced within 20 min to degrees of metallization in excess of 90% at 1100°C, with decrepitation indices significantly below 5%. The degree of metallization of composite pellets increased with an increase in reduction temperature (from 1000 to 1100°C), reduction time (20 min. vs. 40 min), and coke quantity (15% vs. 20%). CMC was identified as the most economical and suitable binder for the Sishen concentrate.     

高铁硫化矿选择性浸出铁的研究

将镍钴火法冶炼转炉渣进行还原硫化,制备成富含镍钴铜的高含铁硫化矿,并采用加压选择性浸出其中的铁。对铁的浸出行为进行了研究。结果表明,随着铜浸出率从98%降到-42%,铁浸出率从3%升到43%左右,选择性浸出后液含铁越来越高,而且以二价铁居多,这是造成高铁硫化矿难以进行加压选浸的主要原因。     

铁矿球团生球的固结机理及强化途径

通过生球强度破坏机理分析,得出通过对造球原料进行润磨可以有效的增大晶粒间的范德华力,增加生球的机械强度,添加能够通过范德华力、静电力、氢键、化学键、配位键等与铁矿颗粒表面发生作用的粘结剂也可以有效地提高生球的机械强度;提高球团的爆裂温度的有效方法是均衡球团表面气化和内部扩散作用,均衡球团表面气化和内部扩散作用的主要措施是降低球团表面气化的速度,使表面扩散速度减小,添加具有亲水基的有机粘结剂和膨润土可以降低自由水或毛细水的扩散速度,提高球团的爆裂温度;通过对造球原料的改性对生球的强度的提高是有限的,添加有机粘结剂或复合粘结剂强化生球强度仍然是今后发展的一个重要方向。     

硫在含碳球团内的转化行为

为了研究含碳球团还原产品中硫含量过高的问题和出路,笔者借鉴高温法定硫的原理,设计了一套分析测定装置,首次系统地研究了铁精矿配加烟煤、无烟煤和生石灰等原料之后的含碳球团在不同温度、时间条件下硫的分解转化行为,得出了煤种、CaO含量、温度和时间等条件对产品硫含量的影响趋势,分析揭示了试验现象与脱硫反应之间的规律,并对含碳球团的工艺选择与环保的关系进行了相应的论述.     

梅山高磷铁矿矿石性质及微生物脱磷的可行性

简要介绍了微生物作用下铁矿石脱磷的概况,通过显微镜鉴定等手段查明了梅山高 磷铁矿石中磷的赋存状况、嵌布特征及磷铁关系,在此基础上进行了Ｔ·ｆ菌氧化黄铁矿产生 酸－酸浸脱磷的初步可行性研究．