High-chromium vanadium-titanium magnetite all-pellet integrated burden optimization and softening-melting behavior based on flux pellets

High-chromium vanadium-titanium magnetite(HVTM)is a crucial polymetallic-associated resource to be developed.The allpellet operation is a blast furnace trend that aims to reduce carbon dioxide emissions in the future.By referencing the production data of vanadium-titanium magnetite blast furnaces,this study explored the softening-melting behavior of high-chromium vanadium-titanium magnetite and obtained the optimal integrated burden based on flux pellets.The results show that the burden with a composition of 70wt%flux pellets and 30wt%acid pellets exhibits the best softening-melting properties.In comparison to that of the single burden,the softening-melting characteristic temperature of this burden composition was higher.The melting interval first increased from 307 to 362℃and then decreased to 282℃.The maximum pressure drop(ΔPmax)decreased from 26.76 to 19.01 kPa.The permeability index(S)dropped from 4643.5 to 2446.8 kPa·℃.The softening-melting properties of the integrated burden were apparently improved.The acid pellets played a role in withstanding load during the softening process.The flux pellets in the integrated burden exhibited a higher slag melting point,which increased the melting temperature during the melting process.The slag homogeneity and the TiC produced by over-reduction led to the gas permeability deterioration of the single burden.The segregation of the flux and acid pellets in the HVTM proportion and basicity mainly led to the better softening-melting properties of the integrated burden.

Diffusion and reaction mechanism of limestone and quartz in fluxed iron ore pellet roasting process

The increase to the proportion of fluxed pellets in the blast furnace burden is a useful way to reduce the carbon emissions in the ironmaking process.In this study,the interaction between calcium carbonate and iron ore powder and the mineralization mechanism of fluxed iron ore pellet in the roasting process were investigated through diffusion couple experiments.Scanning electron microscopy with energy dispersive spectroscopy was used to study the elements’diffusion and phase transformation during the roasting process.The results indicated that limestone decomposed into calcium oxide,and magnetite was oxidized to hematite at the early stage of preheating.With the increase in roasting temperature,the diffusion rate of Fe and Ca was obviously accelerated,while the diffusion rate of Si was relatively slow.The order of magnitude of interdiffusion coefficient of Fe_(2)O_(3)-CaO diffusion couple was 10^(−10) m^(2)·s^(−1) at a roasting temperature of 1200℃for 9 h.Ca_(2)Fe_(2)O_(5) was the initial product in the Fe_(2)O_(3)-CaO-SiO_(2) diffusion interface,and then Ca_(2)Fe_(2)O_(5) continued to react with Fe_(2)O_(3) to form CaFe_(2)O_(4).With the expansion of the diffusion region,the sillico-ferrite of calcium liquid phase was produced due to the melting of SiO_(2) into CaFe_(2)O_(4),which can strengthen the consolidation of fluxed pellets.Furthermore,andradite would be formed around a small part of quartz particles,which is also conducive to the consolidation of fluxed pellets.In addition,the principle diagram of limestone and quartz diffusion reaction in the process of fluxed pellet roasting was discussed.

Simulation of deuterium pellet ablation and deposition in the EAST tokamak with HPI2 code

Pellet injection is a primary method for fueling the plasma in magnetic confinement devices.For that goal the knowledges of pellet ablation and deposition profiles are critical.In the present study,the pellet fueling code HPI2 was used to predict the ablation and deposition profiles of deuterium pellets injected into a typical H-mode discharge on the EAST tokamak.Pellet ablation and deposition profiles were evaluated for various pellet injection locations,with the aim at optimizing the pellet injection to obtain a deep fueling depth.In this study,we investigate the effect of the injection angle on the deposition depth of the pellet at different velocities and sizes.The ablation and deposition of the injected pellet are mainly studied at each injection position for three different injection angles:0°,45°,and 60°.The pellet injection on the high field side(HFS)can achieve a more ideal deposition depth than on the low field side(LFS).Among these angles,horizontal injection on the middle plane is relatively better on either the HFS or the LFS.When the injection location is 0.468 m below the middle plane on the HFS or 0.40 m above the middle plane of the LFS,it can achieve a similar deposition depth to the one of its corresponding side.When the pre-cooling effect is taken into account,the deposition depth is predicted to increase only slightly when the pellet is launched from the HFS.The findings of this study will serve as a reference for the update of pellet injection systems for the EAST tokamak.

Effect of titanium on the sticking of pellets based on hydrogen metallurgy shaft furnace:Behavior analysis and mechanism evolution

Direct reduction based on hydrogen metallurgical gas-based shaft furnace is a promising technology for the efficient and low-carbon smelting of vanadium-titanium magnetite.However,in this process,the sticking of pellets occurs due to the aggregation of metal-lic iron between the contact surfaces of adjacent pellets and has a serious negative effect on the continuous operation.This paper presents a detailed experimental study of the effect of TiO2 on the sticking behavior of pellets during direct reduction under different conditions.Results showed that the sticking index(SI)decreased linearly with the increasing TiO2 addition.This phenomenon can be attributed to the increase in unreduced FeTiO3 during reduction,leading to a decrease in the number and strength of metallic iron interconnections at the sticking interface.When the TiO2 addition amount was raised from 0 to 15wt%at 1100°C,the SI also increased from 0.71%to 59.91%.The connection of the slag phase could be attributed to the sticking at a low reduction temperature,corresponding to the low sticking strength.Moreover,the interconnection of metallic iron became the dominant factor,and the SI increased sharply with the increase in re-duction temperature.TiO2 had a greater effect on SI at a high reduction temperature than at a low reduction temperature.

Pelleting and particle size reduction of corn increase net energy and digestibility of fiber,protein,and fat in corn-soybean meal diets fed to group-housed pigs

Background Reduction of the particle size of corn increases energy digestibility and concentrations of digestible and metabolizable energy.Pelleting may also reduce particle size of grain,but it is not known if there are interactions between particle size reduction and pelleting.The objective of this experiment was to test the hypothesis that particle size reduction and pelleting,separately or in combination,increase N balance,apparent total tract digestibility(ATTD)of fiber and fat,and net energy(NE)in corn-soybean meal diets fed to group-housed pigs.Methods Six corn-soybean meal-based diets were used in a 3×2 factorial design with 3 particle sizes of corn(i.e.,700,500,or 300μm)and 2 diet forms(i.e.,meal or pelleted).Pigs were allowed ad libitum access to feed and water.Twenty-four castrated male pigs(initial weight:29.52 kg;standard diviation:1.40)were allotted to the 6 diets using a 6×6 Latin square design with 6 calorimeter chambers(i.e.,4 pigs/chamber)and 6 periods.Oxygen consumption and CO_(2)and CH_(4)productions were measured during fed and fasting states and fecal and urine samples were collected.Results Regardless of particle size of corn,the ATTD of gross energy(GE),N,and acid-hydrolyzed ether extract(AEE),and the concentration of NE were greater(P<0.05)in pelleted diets than in meal diets.Regardless of diet form,the ATTD of GE,N,and AEE,and the concentration of NE were increased(linear;P<0.05)by reducing the particle size of corn,but the increase was greater in meal diets than in pelleted diets(interaction;P<0.05).Conclusions Both pelleting and reduction of corn particle size increased nutrient digestibility and NE,but increases were greater in meal diets than in pelleted diets.

Persicaria lanigera (Polygonaceae) leaf extract exhibits antiulcerogenic and antiproliferative activities against acetic acid-induced ulcerative colitis and cotton pellet-induced granuloma tissue in rats

Objective:To assess the effect of leaf extract of Persicaria lanigera on cotton pellet-induced granuloma tissue formation and acetic acid-induced ulcerative colitis.Methods:Rats were randomly divided into six groups:normal control,negative control,positive control(dexamethasone or sulfasalazine)as well as Persicaria lanigera(100-600 mg/kg)-treated groups.The effects of the extracts on body weight,antioxidant,and hematological parameters,as well as mast cell proliferation,were assessed.In addition,a histological evaluation was conducted.Results:Persicaria lanigera extract significantly decreased the mean exudate amount and suppressed granuloma tissue formation in a concentration-dependent manner in rats(P<0.05).Additionally,the extract significantly increased body weight,improved hematological profile,reduced the disease activity index score and malondialdehyde level,as well as enhanced catalase and superoxide dismutase activities(P<0.05).Histological evaluation showed Persicaria lanigera extract alleviated acetic acid-induced colonic damages,as evidenced by decreased cell necrosis,edema,and inflammatory cell infiltration.Conclusions:Persicaria lanigera extract possesses antiproliferative,antioxidative,and anti-colitis activities.However,its underlying mechanisms of action need further investigation.

Industrial utilization of arsenic-containing gold dressing tailings as pellet prepared by straight grate process

The utilization of arsenic-containing gold dressing tailings is an urgent issue faced by gold production companies worldwide.The thermodynamic analysis results indicate that ferrous arsenate(FeAsO_(4)),pyrite(FeS_(2))and sodium cyanide(NaCN)in the arsenic-containing gold metallurgical tailings can be effectively removed using straight grate process,and the removal of pyrite and sodium cyanide is basically completed during the preheating stage,while the removal of ferrous arsenate requires the roasting stage.The pellets undergo a transformation from magnetite to hematite during the preheating process,and are solidified through micro-crystalline bonding and high-temperature recrystallization of hematite(Fe_(2)O_(3))during the roasting process.Ultimately,pellets with removal rates of 80.77% for arsenic,88.78% for sulfur,and 99.88% for cyanide are obtained,as well as the iron content is 61.1% and the compressive strength is 3071 N,meeting the requirements for blast furnace burden.This study provides an industrially feasible method for treating arsenic-containing gold smelting tailings,benefiting gold production enterprises.

Probing deactivation by coking in catalyst pellets for dry reforming of methane using a pore network model

Dry reforming of methane(DRM) is an attractive technology for utilizing the greenhouse gases(CO_(2) and CH_(4)) to produce syngas. However, the catalyst pellets for DRM are heavily plagued by deactivation by coking, which prevents this technology from commercialization. In this work, a pore network model is developed to probe the catalyst deactivation by coking in a Ni/Al_(2)O_(3) catalyst pellet for DRM. The reaction conditions can significantly change the coking rate and then affect the catalyst deactivation. The catalyst lifetime is higher under lower temperature, pressure, and CH_(4)/CO_(2) molar ratio, but the maximum coke content in a catalyst pellet is independent of these reaction conditions. The catalyst pellet with larger pore diameter, narrower pore size distribution and higher pore connectivity is more robust against catalyst deactivation by coking, as the pores in this pellet are more difficult to be plugged or inaccessible.The maximum coke content is also higher for narrower pore size distribution and higher pore connectivity, as the number of inaccessible pores is lower. Besides, the catalyst pellet radius only slightly affects the coke content, although the diffusion limitation increases with the pellet radius. These results should serve to guide the rational design of robust DRM catalyst pellets against deactivation by coking.

The Logistics of Production and Supply of Ag Pellets for Industrial Applications in Canada

In this work we analyze the supply of biomass from field to an in-land or port destination. The biomass is pelletized to increase its bulk density to extend its storage period and for ease of its transport. The pellet may be used for conversion to chemicals and animal bedding or for straight combustion. We analyzed supply chain in Saskatchewan where there are plenty of crop residues but widely dispersed and harvest seasons are short. We envisioned that the farmer collects bales from field and transports the bales to farmstead during the harvest season. The bales are then processed into pellets using small scale pellet equipment. A custom operator with expertise in pelletization may engage in handling and densifying the biomass. The business case for the mobile mill will be similar to the well established custom grain and forage harvesting operations. The pellets are stored in hopper bottom grain bins at the farmstead. From this point, the handling of pellets would be similar to the handling and marketing of grain. The farmer trucks a specified volume of pellets from farmstead to the nearest elevator where the pellets are transferred to larger bins or silos. Pellets are extracted from silos and loaded onto the rail cars. The Canadian freight rail companies (mainly CN) currently transport over 3 million dry tonne (dt) of wood pellets in rail cars. The pellets are hauled to marine ports on the West Coast or East Coast for export. The cost of delivering ag pellets to biorefinery or to the shipping port is $86.09/dt. This cost does not include the equivalent value of removing biomass from the farm (e.g. fertilizer replacement) and return on investment. The GHG emissions to produce and transport ag pellets add up to 185.9 kg of CO2 per dt of biomass. The cost of producing pellets without drying feedstock is $35.05/dt and the corresponding GHG for palletization amounts $146.30/dt.

Hydrochar Pelletization towards Solid Biofuel from Biowaste Hydrothermal Carbonization

Hydrothermal carbonization is highly applicable to high moisture biomass upgrading due to the fact that moist-ure involved can be directly used as reaction media under the subcritical-water region.With this,value-added utilization of hydrochar as solid fuel with high carbon and energy density is one of the important pathways for biomass conversion.In this review,the dewatering properties of hydrochar after the hydrothermal carbonization of biowaste,coalification degree with elemental composition and evolution,pelletization of hydrochar to enhance the mechanical properties and density,coupled with the combustion properties of hydrochar biofuel were discussed with various biomass and carbonization parameters.Potential applications for the co-combustion with coal,cleaner properties and energy balance for biowaste hydrothermal carbonization were presented as well as the challenges.

Effect mechanism of aluminum occurrence and content on the induration characteristics of iron ore pellets

With the intensified depletion of high-grade iron ores,the increased aluminum content in iron ore concentrates has become unavoidable,which is detrimental to the pelletization process.Therefore,the effect mechanism of aluminum on pellet quality must be identified.In this study,the influence of aluminum occurrence and content on the induration of hematite(H)and magnetite(M)pellets was investigated through the addition of corresponding Al-containing additives,including alumina,alumogoethite,gibbsite,and kaolinite.Systematic mineralogical analysis,combined with the thermodynamic properties of different aluminum occurrences and the quantitative characterization of consolidation behaviors,were conducted to determine the related mechanism.The results showed that the alumina from various aluminum occurrences adversely affected the induration characteristics of pellets,especially at an aluminum content of more than 2.0wt%.The thermal decomposition of gibbsite and kaolinite tends to generate internal stress and fine cracks,which hinder the respective microcrystalline bonding and recrystallization between Fe2O3particles.The adverse effect on the induration characteristics of fired pellets with different aluminum occurrences can be relieved to varying degrees through the formation of liquid phase bonds between the hematite particles.Kaolinite is more beneficial to the induration process than the other three aluminum occurrences because of the formation of more liquid phase,which improves pellet consolidation.The research results can further provide insights into the effect of aluminum occurrence and content in iron ore concentrates on downstream processing and serve as a guide for the utilization of high-alumina iron ore concentrates in pelletization.

Elucidating the suppression of lithium dendrite growth with a void-reduced anti-perovskite solid-state electrolyte pellet for stable lithium metal anodes

Solid-state lithium-metal batteries,with their high theoretical energy density and safety,are highly promising as a next-generation battery contender.Among the alternatives proposed as solid-state electrolyte,lithium-rich anti-perovskite(Li RAP)materials have drawn the most interest because of high theoretical Li^(+)conductivity,low cost and easy processing.Although solid-state electrolytes are believed to have the potential to physically inhibit the lithium dendrite growth,lithium-metal batteries still suffer from the lithium dendrite growth and thereafter the short circuiting.The voids in practical Li RAP pellets are considered as the root cause.Herein,we show that reducing the voids can effectively suppress the lithium dendrite growth.The voids in the pellet resulted in an irregular Li^(+)flux distribution and a poor interfacial contact with lithium metal anode;and hence the ununiform lithium dendrites.Consequently,the lithium-metal symmetric cell with void-reduced Li_(2)OHCl-HT pellet was able to display excellent cycling performance(750 h at 0.4 m A cm^(-2))and stability at high current density(0.8 m A cm^(-2)for 120 h).This study provides not only experimental evidence for the impact of the voids in Li RAP pellets on the lithium dendrite growth,but also a rational pellet fabrication approach to suppress the lithium dendrite growth.

The Application of Electron-Beam Welding in Pellet Mold Preparation

This paper provides insight into the application of electron-beam welding in pellet mold preparation,highlighting the importance of the combination of electron-beam welding and pellet mold preparation in the fields of microstructure joining and micro-and nanostructure preparation.Precise material joining and microstructure fabrication can be achieved by the precise control of electron-beam welding and the shape adjustment of pellet molds.These applications hold significant potential in the modern industrial field,providing robust support for the development of new materials and the growth of the petrochemical industry.This paper asserts that in the future,the ongoing development of electron-beam welding and pelletizing template technology will unlock new possibilities in the field of petrochemicals,fostering progress in science and technology.

中国废旧军服面料回收利用的研究现状及发展前景

为促进废旧军服面料的高值化回收利用,总结了国内07式军服的种类及其面料特征,系统分析了目前开纤纺纱法、再生聚酯切片法、涤棉分离技术等废旧军服面料的回收利用方法,并对废旧军服面料回收再利用的发展前景进行展望。分析表明:目前废旧军服面料的回收利用主要聚焦于简单再利用或回收涤纶组分制备高值再生聚酯切片,较少关注军服面料中其余组分的高值回收利用。针对废旧军服面料中含量相对较高的涤棉混纺面料,采用有效的涤棉分离技术高效分离涤纶和棉纤维,并以此作为原料分别制备再生聚酯切片和再生溶解浆,进一步以再生棉浆粕为原料制备再生纤维素产品将非常有前景。因而,开发高效的涤棉分离、废旧涤纶和棉纤维的高值化利用技术是实现废旧军服面料综合利用的重要发展方向。

桉木屑颗粒燃料固体桥结构构建与燃烧特性研究

在成型燃料内部构建固体桥结构可有效改善其物理品质,利用不同粒径桉木屑构建了具有固体桥结构的颗粒燃料,并进一步研究了颗粒燃料的燃烧特性。提出的构建方法为同种原料不同粒径混配成型,在电子压力机上进行了粒径(0,1 mm]原料混配粒径(4 mm, 5 mm]原料的颗粒压缩成型实验,结果显示混配量5%~10%时颗粒内部长粒径粒子的交叉缠绕,可形成适量的固体桥结构,短粒径粒子填充饱满,粒子间结合紧密。较佳的混配量为5%,颗粒具有较高的松弛密度,为1 074.79 kg/m^(3),最高的Meyer强度,为23.93 MPa,最低的比能耗,为27.06 kJ/kg,平衡含水率为11.65%,吸水速率k为0.015 3 min^(-1)。在热分析仪上进行了成型颗粒燃烧实验,颗粒燃烧过程较为平稳且有所延长,在升温速率10~40℃/min的范围内,着火温度Ti在246.60~265.00℃之间,最大失重速率(dm/dτ)_(1max)在-6.84~-29.10%/min之间,综合燃烧指数S在7.26×10^(-12)~1.09×10^(-10)min^(-2)·K^(-3)之间。在X射线荧光光谱仪上分析了颗粒灰分的元素组成,预测颗粒燃烧时具有中等或较高的结渣沾污趋势。

京唐5500m^(3)高炉超高比例碱性球团矿冶炼实践

随着京唐5500m^(3)高炉入炉球团矿的比例>50%,酸性球团矿难以满足冶炼造渣要求,为此开发了碱度>1.1的球团矿,目前入炉碱性球团矿的比例保持在55%左右,单座高炉最高超过70%。针对超高比例碱性球团矿冶炼,采取了一系列措施,在精料方针方面,主要是改善碱性球团矿质量、稳定焦炭质量、控制碱金属负荷;在操作制度方面,主要是调整装料制度及送风制度、制订合理的热制度及造渣制度。3座高炉保持了长期稳定运行,主要技术经济指标维持在较好水平,其中1号高炉焦比最低降至257kg/t,燃料比最低496kg/t,焦炭负荷最高6.18,利用系数最高2.62(m^(3)·d)

颗粒脂肪联合纳米脂肪移植治疗重睑术后上睑凹陷的临床应用

目的:探讨颗粒脂肪联合纳米脂肪移植治疗重睑术后上睑凹陷的临床疗效。方法:选取2018年7月-2022年2月笔者科室应用颗粒脂肪联合纳米脂肪移植治疗重睑术后上睑凹陷的13例患者(20只眼)。抽取脂肪后,处理成颗粒脂肪和纳米脂肪。每只眼注射颗粒脂肪1.2~2.0 ml,纳米脂肪0.2~0.8 ml。结果:随访6~12个月,17只眼疗效良好;2只眼矫正不足,3个月后再次移植颗粒脂肪和纳米脂肪;1只眼眼尾分叉,6个月后行切开重睑修复,再次治疗后疗效均较好。结论:颗粒脂肪联合纳米脂肪移植治疗重睑术后上睑凹陷疗效好、创伤小、恢复快。

预造球强化难制粒精矿烧结工艺

随着进口铁矿石价格的增长,充分利用廉价的难处理铁矿资源成为钢铁企业降本增效的关键。本文针对难制粒精矿在烧结中利用率低的问题,在复合造块法的基础上开发了预造球工艺,显著提高了难制粒精矿的配入量,有效改善了制粒效果与烧结产、质量指标。研究表明,在难制粒精矿配比达到36%时,采用预造球制粒可以使准颗粒平均粒径提高1.53 mm,透气性指数提高0.17。在此基础上,垂直烧结速度提高13.97 mm/min,利用系数提高0.815 t/(m^(2)·h),转鼓强度提高3.39%。预造球烧结中,由于难制粒精矿的分离,常规制粒料部分的制粒性能得到优化,局部碱度得到提高,形成大量的针柱状铁酸钙。在常规制粒料与球团料交界处固相固结与液相固结同时存在,铁酸钙与铁氧化物相互交织,形成球团嵌入式分布的成品矿结构,具有良好的成矿效果和强度性能。

钒钛磁铁矿带式焙烧机球团质量提升工艺研究及实践

攀钢西昌带式焙烧机生产线是国内第一条钒钛矿带式焙烧机球团生产线,投产后成品球平均抗压强度偏低,单个成品球团矿平均抗压强度≥1950 N。本文从原料结构、造球工序、带式焙烧机工艺操作等方面分析原因,采取的优化措施包括:控制原料中TiO_(2)质量分数≤12%、V_(2)O_(5)质量分数≤1%、Al_(2)O_(3)质量分数<2.0%、MgO质量分数<1.8%,精矿粒度-200目占比75%~80%,碱度应控制0.6倍左右,膨润土配比应适当降低至1.2%~1.4%,生球粒度10~12.5 mm占比≥60%;重力除尘灰配比>1.5%,或者烧结机头除尘灰配比>1.5%;焙烧机工艺操作制度为鼓干段温度300~330℃、抽干段温度370~390℃、预热温度梯度500℃→1200℃、焙烧段温度1230~1240℃、大烟罩内氧质量分数17.3%~18.0%。工艺优化后,单个球团平均抗压强度约2348 N,达到了考核指标;排放烟气中烟尘含量2.54 mg/Nm^(3)、SO_(2)含量3.13 mg/Nm^(3)、NO_(x)含量41.42 mg/Nm^(3)、基准氧含量17.54%,均满足国家排放标准。

带式焙烧机均匀布料研究与应用

为适应绿色低碳钢铁冶炼目标,球团大型化生产成为必然需求。由于带式焙烧机料层较厚,且焙烧过程球团处于静态,为保证成品球质量,生球的均匀布料就显得尤为重要。本文通过研究带式焙烧机布料原理和布料工艺设备参数,确定其合理的布料方式。研究结果表明:梭车和摆头皮带机布料均存在生球落下次数多、布料不均匀等问题;往复式布料器布料能够减少生球落下次数,且能够实现单向布料,快速换向,从而保证均匀布料。通过参数计算,得出504 m^(2)带式焙烧机合理的布料方式为往复式布料器+宽皮带机布料,卸料小车移动速度和皮带运行速度均应控制在0.65 m/s,宽皮带机运行速度应控制在0.12 m/s。生产实践表明在该布料方式下,布料轨迹整齐,台车料面平整,成品球强度均匀,达到了预期的研究目标。