Basic characteristics of Australian iron ore concentrate and its effects on sinter properties during the high-limonite sintering process

The basic characteristics of Australian iron ore concentrate (Ore-A) and its effects on sinter properties during a high-limonite sintering process were studied using micro-sinter and sinter pot methods. The results show that the Ore-A exhibits good granulation properties, strong liquid flow capability, high bonding phase strength and crystal strength, but poor assimilability. With increasing Ore-A ratio, the tumbler index and the reduction index (RI) of the sinter first increase and then decrease, whereas the softening interval (Delta T) and the softening start temperature (T (10%)) of the sinter exhibit the opposite behavior; the reduction degradation index (RDI+3.15) of the sinter increases linearly, but the sinter yield exhibits no obvious effects. With increasing Ore-A ratio, the distribution and crystallization of the minerals are improved, the main bonding phase first changes from silico-ferrite of calcium and aluminum (SFCA) to kirschsteinite, silicate, and SFCA and then transforms to 2CaO center dot SiO2 and SFCA. Given the utilization of Ore-A and the improvement of the sinter properties, the Ore-A ratio in the high-limonite sintering process is suggested to be controlled at approximately 6wt%.

Optimal proportioning of iron ore in sintering process based on improved multi-objective beluga whale optimisation algorithm

Proportioning is an important part of sintering,as it affects the cost of sintering and the quality of sintered ore.To address the problems posed by the complex raw material information and numerous constraints in the sintering process,a multi-objective optimisation model for sintering proportioning was established,which takes the proportioning cost and TFe as the optimisation objectives.Additionally,an improved multi-objective beluga whale optimisation(IMOBWO)algorithm was proposed to solve the nonlinear,multi-constrained multi-objective optimisation problems.The algorithm uses the con-strained non-dominance criterion to deal with the constraint problem in the model.Moreover,the algorithm employs an opposite learning strategy and a population guidance mechanism based on angular competition and two-population competition strategy to enhance convergence and population diversity.The actual proportioning of a steel plant indicates that the IMOBWO algorithm applied to the ore proportioning process has good convergence and obtains the uniformly distributed Pareto front.Meanwhile,compared with the actual proportioning scheme,the proportioning cost is reduced by 4.3361¥/t,and the TFe content in the mixture is increased by 0.0367%in the optimal compromise solution.Therefore,the proposed method effectively balances the cost and total iron,facilitating the comprehensive utilisation of sintered iron ore resources while ensuring quality assurance.

Mineralogical properties and co-sintering characteristics of fluxed iron ore with magnetite concentrates

To investigate the feasibility of co-sintering of fluxed iron ore with magnetite concentrates, the mineralogical properties of a novel fluxed iron ore were studied using particle size analysis, microscopic morphology characterization, and X-ray diffraction Rietveld analysis. Following that, the experiments for granulation performance and basic sintering characteristics were designed under seven different fluxed iron ore ratios, and the integrated ranking of different fluxed iron ore ratios was determined using gray relation analysis. Finally, the results of the industrial trails were combined with the feasibility analysis. Test and experimental results show that the fraction of the fluxed iron ore particles larger than 0.5 mm can account for more than 48%, and the particles have two morphologies: spherical-rough and flaky-smooth. Ca elements are found in the form of calcite (CaCO3) and dolomite (CaMg(CO3)2). The average particle size of granules and powder removal rate can be improved from 2.50 to 3.16 mm and 39.60% to 24.20%, respectively, with the increase in the fluxed iron ore ratio. Furthermore, the fluxed iron ore can improve assimilability and liquid fluidity of magnetite concentrates. In terms of overall granulation performance and sintering characteristics, the fluxed iron ore ratios are graded from best to worst as follows: 12%, 15%, 9%, 18%, 21%, 6% and 3%. The industrial trails show that when the fluxed iron ore ratio is increased, the beneficial effect of the superior sintering characteristics of the fluxed iron ore itself is ideally balanced with the negative effect of the lower amount of additional CaO at 12% ratio, and thus, it is feasible to bring the fluxed iron ore into production at a level of roughly 12%.

Emission characteristics and control technology of heavy metals during collaborative treatment of municipal solid waste incineration fly ash in iron ore sintering process

The municipal solid waste incineration fly ash (MSWI-FA) contains a large amount of heavy metals, and the process of iron ore sintering and treating fly ash needs to pay attention to the migration characteristics of heavy metals. The impact of the application of MSWI-FA in the sintering process on the emission law of heavy metals in the collaborative treatment process was studied, and corresponding control technologies were proposed. The results showed that the direct addition of water washing fly ash (WM-FA) powder resulted in varying degrees of increase in heavy metal elements in the sinter. As the amount of WM-FA added increases, the content of heavy metal elements correspondingly increases, and an appropriate amount of WM-FA added is 0.5%–1.0%. The migration mechanism of heavy metals during the sintering treatment of WM-FA was clarified. Heavy metals are mainly removed through direct and indirect chlorination reactions, and Cu and Cr can react with SiO_(2) and Fe_(2)O_(3) in the sintered material to solidify in the sinter. Corresponding control techniques have been proposed to reduce the heavy metal elements in WM-FA through the pre-treatment of WM-FA. When the WM-FA was fed in the middle and lower layers of the sintered material, the high temperature of the lower layer was utilized to promote the removal of heavy metals. The Ni element content has decreased from 130 to 90 mg kg^(−1), and the Cd removal rate has increased by 23%. The removal rates of Cd and Cr elements increase by 2.4 and 5.5 times, respectively. There is no significant change in sintering indexes.

Comprehensive evaluation of sintering basic characteristics of iron ore based on grey relational analysis

Sintering basic characteristics of fourteen iron ores were comprehensively evaluated using micro-sinter and grey relational analysis methods. The results show that magnetite has a low assimilability, high bonding phase strength, and high crystal strength. Hematite presents a good assimilability, while limonite exhibits a strong assimilability, but the bonding phase strength and crystal strength of these two kinds of iron ores are comparatively low. Great difference in liquid flowability exists for the same kind of iron ores. When the assimilation temperature of the sinter mixture is too high, limonite can be added;when the bonding phase strength or crystal strength of the sinter mixture is too low, magnetite can be added. The liquid fluidity of the sinter mixture can be adjusted according to the ratios of corresponding iron ores. Grey relational analysis is an effective method to evaluate the comprehensive sintering characteristics of iron ores, which can provide theoretical basis for the purchasing department of the steel enterprises.

Melting Characteristics of Iron Ore Fine During Sintering Process

The whole melting curve of iron ore during sintering process was obtained,and the melting characteristics of iron ore were defined and explained. The whole melting process of mixture,mixed by iron ore and CaO reagent at basicity of 2.0 and 4.0,respectively,was observed using a SiC heating furnace with camcorder unit,and the melting curves of mixture that were relative height vs temperature curves were obtained. Besides,the melting characteristics of iron ore during sintering were introduced through defining some points in the melting curves,such as liquid forming temperature,inflexion temperature and flowing temperature,and the meaning of different shapes of the melting curves was clarified.

Detection of the assimilation characteristics of iron ores: Dynamic resistance measurements

Resistance in iron ore undergoes a sharp change of up to several orders of magnitude when the sintered solid phase changes to liquid phase.In view of the insufficiency of existing assimilation detection methods,a timing-of-assimilation reaction is proposed,which was judged by continuously detecting the changes in resistance at the reaction interface.Effects of pole position and additional amounts of iron ore on assimilation reaction timing were investigated.The results showed that the suitable depth of pole groove was about 2 mm,and there was no obvious impact when the distance of the poles changed from 4 to 6 mm,or the amount of iron ore changed from 0.4 to 0.6 g.The temperature of sudden change of resistance in the temperature-resistant image was considered to be the lowest assimilation temperature of iron ore.The accuracy of this resistance method was clarified by X-ray diffraction,optical microscope,and scanning electron microscope/energy dispersive spectrometer(SEM/EDS)analyses.

Reduction of NO_(x)emission based on optimized proportions of mill scale and coke breeze in sintering process

Reducing NO_(x) emission of iron ore sintering process in a cost effective manner is a challenge for the iron and steel industry at present.Effects of the proportion of mill scale and coke breeze on the NO_(x) emission,strength of sinter,and sinter indexes were studied by com-bustion and sinter pot tests.Results showed that the peak value of NO concentration,total of NO emission,and fuel-N conversion rate gradu-ally decreased as the proportions of the mill scale increased because NO was reduced to N_(2) by Fe_(3)O_(4),FeO,and Fe in the mill scale.The strength of sinter reached the highest value at 8.0wt%mill scale due to the formation of minerals with low melting point.The fuel-N conver-sion rate slightly fluctuated and total NO_(x) emission significantly decreased with the decreased proportions of coke breeze because CO forma-tion and content of N element in the sintered mixture decreased.However,the sinter strength also decreased due to the decrease in the amount of the melting minerals.Furthermore,results of the sinter pot tests indicated that NO_(x) emission decreased.The sinter indexes performed well when the proportions of mill scale and coke breeze were 8.0wt%and 3.70wt%respectively in the sintered mixture.

Some basic properties of granules from ore blends consisting of ultrafine magnetite and hematite ores

Some basic properties of granules,including the granule size distribution,packed-bed permeability,and chemical composition of the adhering layer,were investigated in this study for four iron ore blends consisting of 5wt%,25wt%,and 45wt%ultrafine magnetite and 25wt%ultrafine hematite concentrates.The effects of varying the sinter basicity(CaO/SiO2 mass ratio=1.4 to 2.2)and adding ultrafine concentrates on the variation of the adhering-layer composition and granule microstructure were studied.Moreover,the effect of adhering-layer compositional changes on sintering reactions was discussed in combination with pot sintering results of ore blends.Increasing sinter basicity led to an increase in the basicities of both the adhering layer and the fine part of the sinter mix,which were higher than the overall sinter basicity.When the sinter chemistry was fixed and fine Si-bearing materials(e.g.,quartz sand)were used,increasing the amount of ultrafine ores in the ore blends tended to reduce the adhering-layer basicity and increase the SiO2 content in both the adhering layer and the fine part of the sinter mix,which will induce the formation of low-strength bonding phases and the deterioration of sinter strength.The adhering-layer composition in granules can be estimated in advance from the compositions of the-1 mm fractions of the raw materials.

铁矿粉种类和成分对其烧结基础特性的影响

铁矿粉的同化性能、黏结相强度与液相流动性等基础特性是烧结优化配矿的重要基础。对BX、YLJ和NFJ等多种铁矿粉进行基础特性检测,并将2种及2种以上铁矿粉混合进行拓展研究。分析铁矿粉基础性能的主要影响因素和三大矿种的基础性能特征,提出基于同化性能、液相流动性的互补配矿思路,为增加性价比高的缺陷矿用量、提高生产质量、降低配矿成本提供理论指导。

铁矿石的烧结基础特性之新概念

长期以来，人们对烧结用铁矿石的评价主要集中在化学成分、粒度组成、矿物特征等常温性能方面，而对铁矿石在烧结过程中的高温行为和作用知之甚少．根据对这一问题的深入思考和实验室的基础研究，提出了“铁矿石的烧结基础特性”的概念．该概念包括同化性能、液相流动性，粘结相强度性能和铁酸钙生成性能等．研究烧结过程中这些高温物理特性，有利于完善烧结理论、改善烧结矿质量和优化烧结工艺过程．

包钢常用铁矿粉烧结基础特性

采用微型烧结法研究了包钢常用六种铁矿粉的烧结基础特性.结果表明,不同铁矿粉的烧结基础特性差别较大.铁矿粉的CaF_2,FeO,MgO,SiO_2和结晶水含量是影响其烧结基础特性的主要因素.包钢含氟磁铁矿的烧结基础特性为同化温度低于1250℃,液相流动性指数大于8.0,粘结相自身强度低于450N/个,铁酸钙生成量小于10%,连晶固结强度高于560N/个.

邢钢烧结原料基础特性及优化配矿试验研究

采用微型烧结试验装置,对邢钢烧结厂常用的7种铁矿粉的基础特性进行了系统研究。结果表明:7种铁矿粉的同化性能、流动性性能、粘结性强度、铁酸钙生成特性、吸水性有较大差异。杂料的同化性最好,同化温度为1 200℃;混合矿的流动性最好,流动性指数为1.69;低硅酸精粉的粘结相强度最高,为4 548 N;杂料的吸水性最高,为36.32%。基于邢钢现场原料条件,进行了烧结优化配矿试验研究,通过降低混合矿中澳矿配比、提高本地碱精粉配比,混合料的基础特性有一定改善,其中同化温度提高了20℃,流动性指数降低到1.27,粘结相强度提高了281 N,最大吸水率降低了1个百分点。烧结杯试验结果表明:垂直烧结速度有所改善,成品率提高了4.5个百分点,成品烧结矿转鼓强度提高了2个百分点,低温还原粉化指数提高了3个百分点,还原性能、荷重软化性能均有所改善。研究结果为邢钢提高本地矿配比、优化配矿、改善烧结矿质量提供了理论依据。

马钢烧结优化配矿技术的研究

对马钢常用的10种铁矿粉的同化性、液相流动性、粘结相自身强度、SFCA生成特性、连晶固结强度等高温烧结特性进行了研究。在此基础上,根据铁矿粉高温特性互补原理,设计了五组烧结优化配矿方案并进行了烧结杯试验,均获得了良好的烧结效果,验证了基于铁矿粉高温特性的烧结优化配矿方法的可行性,为马钢充分利用铁矿粉资源、降低配矿成本,改善烧结矿质量提供了对策。

马钢铁矿粉烧结优化配矿实验研究

使用高温特性测定装置研究马钢12种铁矿粉的同化性、液相流动性、粘结相自身强度和铁酸钙生成特性等高温烧结特性。根据铁矿粉高温特性互补原理设计3种优化配矿方案,并进行烧结杯实验。实验结果表明3种优化配矿方案中,将精矿粉的质量分数由基准方案的7.16%提高到15%,其中低品位高硅OR-7矿质量分数占到,所配烧结矿可获得与基准方案相当或略优的质量指标与经济指标。由此表明基于铁矿粉高温特性的烧结优化配矿方案的可行性与优越性。

蒙古矿优化配矿的烧结基础特性研究

采用微型烧结法系统地研究了蒙古矿烧结基础特性,通过测定配加不同比例蒙古矿的烧结矿强度,利用矿相显微镜观察显微结构和形貌,分析了不同蒙古矿配比条件下各种配矿结构的同化性、液相流动性、铁酸钙生成特性和粘结相自身强度。研究结果表明:60%蒙古矿+20%澳矿+20%自产矿的综合性能最好;56%蒙古矿+17%自产矿+27%巴润矿的次之;40%蒙古矿+8%澳矿+16%自产矿+36%巴润矿的最差。所得实验结论为包钢优化配矿提供了理论依据。

基于铁矿粉烧结基础性能的优化配矿研究

以提高烧结矿性能为目标,对国内两种铁矿粉以及国外三种铁矿粉进行了同化性能、液相流动性能、粘结相强度三个方面分析研究,并据烧结矿各项性能指标制定出配矿方案进行优化实验,探寻最佳配矿比例。结果表明,五种铁矿粉中自产矿的各项性能最优,其他四种铁矿粉的各项烧结基础性能优势各不相同。其次,根据实验结果制定出优化配矿方案,对比混合矿的各项基础特性,得出最优化配矿方案:自产矿为50%,鞍千矿为20%,巴西B为15%,澳矿为10%,巴西A为5%,为现场烧结生产提供了理论依据。

武钢用铁矿粉烧结基础特性的试验研究

采用铁矿粉微型烧结装置对武钢12种铁矿粉的烧结基础特性进行研究。通过分析铁矿粉的高温性能指标,对矿粉的烧结基础特性进行了评价,为烧结厂提出合理的配矿依据,对优化配矿乃至烧结过程具有重要的意义。

包钢烧结优化配矿的基础研究

采用微型烧结试验装置,对包钢常用铁矿粉进行了烧结基础特性的试验研究.结果表明,不同铁矿粉的烧结基础特性差别较大.铁矿粉CaF2,FeO,MgO,SiO2和结晶水含量是影响其烧结基础特性的主要因素.铁矿石烧结基础特性的研究对实现烧结优化配矿,乃至优化烧结过程均具有重要的现实意义.

一种新型澳矿的烧结基础特性研究

对即将投放市场的一种新型澳矿进行了矿物组成和显微结构分析,对其烧结基础特性进行了研究,并与目前国内广泛使用的矿粉进行了比较。结果表明:该矿属于典型的褐铁矿,烧损较高,显微结构以豆状和肾状为主;其同化性能较好,1 280℃经过3 min即完全同化,强于磁铁矿和赤铁矿;液相流动性也较好,粘结相自身强度略低,但连晶固结强度较高;铁酸钙生成能力较好,在碱度为1.8时,铁酸钙的生成量为66%。