Gas-solid reduction kinetic model of MgO-fluxed pellets

The reduction process of MgO-fluxed pellets was investigated and compared with traditional acidic pellets in this paper. Based on the piston flow concept and experimental data, a kinetic model fitting for the gas-solid phase reduction of pellets in tubular reactors （blast furnace, BF） was built up, and the equations of reduction reaction rate were given for pellets. A series of reduction experiments of pellets were carried out to verify the model. As a result, the experimental data and calculated result were fitted well. Therefore, this model can well describe the gas-solid phase reduction process and calculate the reduction reaction rate of pellets. Besides, it can give a better explanation that the reduction reaction rate （reducibility） of MgO-fluxed pellets is better than that of traditional acidic pellets in BF.

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.

Slag Characteristics of Biomass Pellet Fuels with Different Additives to Tobacco-Stalk for Tobacco Curing Heating

Since pure tobacco stalk(TS)biomass pellet fuels tend to slag,five anti-slagging agents were added to the crushed TS to obtain a pellet fuel that could be used in biomass burners to provide heat for tobacco curing.The obtained results revealed that the main component of TS pellet fuel was K_(2)Si_(2)O_(5).During fuel combustion process,additives generated higher melting point silicate compounds by Al–K,Ca–K,and Ca–K elemental structures to replace single K elemental structure of TS,enhancing the anti-slagging efficiency of the pellet fuel from 21.63%to 78.29%and promoting the precipitation of K,Mg,and Na elements in the slag block.By investigating the anti-slagging mechanism pathways of the additives in TS biomass pellet fuels,altering of the structure of silicate ion group pathway was found to improve anti-slagging effects that met the requirements of production formula.

Recycling of waste E-cigarette butts as engineered pelletized fibres for sustainable stone mastic asphalt

The disposal of discarded E-cigarette butts(E-CBs) presents significant environmental challenges due to their detrimental impacts on ecosystems. To find an environmentally sustainable method for managing this waste, the potential for recycling E-CBs in asphalt pavements was investigated in this study. By focusing on the two primary components of E-CBs, namely cellulose fibre and polylactic acid(PLA), this research introduced a novel approach for recycling E-CBs in stone mastic asphalt(SMA) as a fibre additive in engineered pellet form. The prepared fibre pellets were directly added to aggregates to produce the SMA mixture. The resulting mixtures underwent a comprehensive evaluation through a series of standardized laboratory tests, including assessments of volumetric properties, indirect tensile strength(ITS), stiffness modulus, moisture susceptibility, and rutting resistance. The results were compared with SMA mixtures containing conventional cellulose fibres. Additionally, to examine the potential influence of PLA, a third mixture was prepared, incorporating both cellulose fibre and PLA. The findings indicate that the SMA using pelletized fibre can satisfy the technical specifications regarding the tests performed in this study, showing higher ITS and rutting resistance compared to the reference mixture. Moreover, the incorporation of PLA plastic reduced air void content and improved tensile strength, stiffness, and rutting resistance. This study highlights the potential for recycling E-CBs in asphalt mixtures, offering technical support for further development of sustainable recycling methods for this waste.

Application of Splitting (Cross Validation) Technique and Herzberg Equation in Feed Pellet Quality Prediction Models

The present study had the objectives to apply the splitting technique in feed pellet quality prediction models and validate these models through Herzberg equation.The independent factors(input data)were the particle size(PS:coarse and medium),heat treatment(HT:expanded-pelleted and pelleted),fat addition levels(FA:15,25,35 and 45 g/kg of feed)and moisture addition levels(MA:0,7,14 and 21 g/kg of feed)which were combined in a full factorial design(2×2×4×4),resulting in 64 different treatments with eight replicates each.The intact pellets amount and pellet durability index(PDI)were considered as the model’s output data.In the splitting technique the whole data set,composed by 512 observations,were splitted in two data set:(1)model construction set(75%of the total data)and(2)model validation set(25%of the total data set,which were selected randomly from the original data set).Both equations,the one obtained by splitting method and the one obtained by whole data set,had good coefficient of determination and similar residues square means.It was concluded that splitting technique can be successfully applied to fit a prediction equation for feed pelleting process and that Herzberg equation consists in a useful tool to validate the coefficient of determination of those models.

MnCe-Al_(2)O_(3)球形颗粒的制备及其催化燃烧环己烷性能

挥发性有机物(VOCs)的大量排放会导致环境污染和健康危害,催化燃烧是高效降解VOCs的重要手段之一.采用海藻酸盐溶胶-凝胶法合成了MnCe-Al_(2)O_(3)球形颗粒作为环己烷催化燃烧催化剂,结果表明,Mn催化剂中适当添加Ce可提高MnOx的分散性,降低催化剂H_(2)-TPR还原温度.催化剂中Mn和Ce摩尔比为3∶1、煅烧温度650℃时,催化剂催化燃烧环己烷活性最高,可以在345℃实现环己烷的完全转化.反应24 h后,催化剂仍显示出几乎100%的环己烷转化率,表现了良好的催化稳定性.与浸渍法制备的催化剂相比,MnCe-31-Al_(2)O_(3)-650催化剂活性更高.

激活的富血小板血浆促进Pellet培养的脂肪间充质干细胞成软骨样分化

目的探讨激活的富血小板血浆(PRP)对Pellet培养的人脂肪来源间充质干细胞向软骨样细胞分化及相关信号通路的影响。方法添加不同比例(5%、10%和15%)的激活PRP,检测不同培养时间(1、3、5、7、9、11 d)脂肪干细胞的增殖能力。将采用Pellet培养的P3代的h ADSCs分为3组,对照组、激活PRP组和含TGF-β3的软骨诱导组,持续培养21 d后,阿利新蓝和苏木精-伊红染色进行软骨分化鉴定,real-time PCR测定Sox-9、Aggrecan和II型胶原的基因表达,DMMB法测定胞外基质中GAG含量,Western blot进一步检测对照组和激活PRP组中Sox-9、Gli-1和BMP-2蛋白的表达。结果 MTT实验结果显示,在10%激活PRP培养条件下,11 d的生长时间内hADSCs的增殖率最适宜。阿利新蓝和苏木精-伊红染色显示,激活PRP组和软骨诱导组中软骨表达呈阳性。Real-time PCR结果表明软骨诱导组其Sox-9、Aggrecan和II型胶原mRNA表达的能力高于激活PRP组(P<0.05)。GAG实验结果显示,软骨诱导组促GAG分泌的能力优于激活PRP组(P<0.05)。Western blot结果显示,相比对照组,激活PRP组中伴随Gli-1和BMP-2的蛋白表达升高,而Sox-9蛋白表达随之升高。结论激活PRP刺激hADSCs的最适增殖能力的浓度比例为10%。激活PRP和软骨诱导剂对脂肪干细胞成软骨分化中的诱导表达具有相似的能力,激活PRP对h ADSCs诱导成软骨作用与Hedgehog和BMP信号通路有关。

Effect of Na_2CO_3 on reduction and melting separation of ludwigite/coal composite pellet and property of boron-rich slag

The effects of Na_2CO_3 on the reduction and melting separation behavior of ludwigite/coal composite pellet, the desulfurization ratio and the property of the separated boron-rich slag were investigated at laboratory scale in the present work. Na_2CO_3 could improve the reduction rate of the composite pellet to some extent. The melting separation of the composite pellet became increasingly difficult with the increase of Na_2CO_3 in the pellet due to the sharply increasing of the melting point of slag. The sulfur content of the iron nugget gradually decreased from 0.27% to 0.084%（mass fraction） with the Na_2CO_3 content in the pellet increasing from 0 to 6%. The efficiency of extraction of boron（EEB） of the slow cooled boron-rich slag decreased from 86.46% to 59.52% synchronously. Na_2CO_3 had obviously negative effect on melting separation of the composite pellet and boron extraction of the boron-rich slag.

臭氧气浮-核晶造粒工艺处理油气田采出水与再生利用

为解决油气田采出水水量大、水质复杂等难题,实现油气田采出水处理后再利用的目标,提出一套臭氧气浮-核晶造粒组合工艺,处理后采出水可满足配制胍胶压裂液的水质要求。以COD和SS去除率为评价指标,对比了预臭氧氧化-混凝和臭氧气浮两种工艺,结果表明臭氧气浮工艺对COD和SS的处理效果更佳,二者去除率分别可达到59%和88%,处理后COD和SS均满足配制胍胶压裂液的水质要求。以Ca^(2+)、Mg^(2+)去除率为硬度指标,对比了核晶造粒和化学沉淀两种工艺的除硬效果,结果表明核晶造粒工艺在除硬方面具有显著优势,对Ca^(2+)、Mg^(2+)的总去除率能达到86%,满足配制胍胶压裂液对硬度的要求。以长庆油田4个站点采出水为实际处理对象,采出水经臭氧气浮-核晶造粒工艺处理后,配制的胍胶压裂液均表现出较好的基液黏度,可挑挂且不易断裂。臭氧气浮-核晶造粒工艺不仅可实现采出水的资源化利用,还可减少企业日常生产成本,具有较好的经济和环境效益,为油气田采出水的资源化利用提供了技术参考。

天王补心丹通过调节生物钟反馈环路治疗失眠的作用机制

目的:探讨天王补心丹通过调节生物钟反馈环路治疗失眠的作用机制。方法:40只SD大鼠分为正常组、模型组、天王补心丹低、高剂量组,每组10只。除正常组外,其他各组腹腔注射4-氯-DL-苯丙氨酸(PCPA)2 d构建失眠大鼠模型。造模后天王补心丹组分别予以低剂量(2.2 g·kg^(-1)·d^(-1))、高剂量(8.7 g·kg^(-1)·d^(-1))灌胃,正常组和模型组给予等量生理盐水灌胃,共7 d。采用翻正实验检测模型制备是否成功。干预第3天采用Morris水迷宫测试。干预第7天进行旷场实验。Western Blot法检测下丘脑组织中时钟基因蛋白Clock、Bmal1、Per1、Cry2表达水平。q-PCR检测下丘脑组织中Clock、Bmal1、Per1、Cry2 mRNA相对表达水平。结果:(1)翻正实验中,与正常组比较,模型组睡眠潜伏期延长,且睡眠时长缩短(P<0.05)。(2)Morris水迷宫实验中,与正常组比较,模型组大鼠逃避潜伏期延长(P<0.05),穿越逃生平台次数减少(P<0.05);与模型组比较,天王补心丹各剂量组逃避潜伏期均下降,穿越逃生平台次数增多(P<0.05)。(3)旷场实验中,与正常组比较,模型组大鼠中央网格活动路程与总活动路程减少(P<0.05);与模型组比较,天王补心丹各剂量组大鼠的中央网格活动路程与总活动路程明显增加(P<0.05)。(4)与正常组比较,模型组大鼠Clock、Bmal1蛋白表达量下降(P<0.05),Per1、Cry2蛋白表达升高(P<0.05);与模型组比较,天王补心丹高剂量组Clock、Bmal1蛋白表达上调(P<0.05),天王补心丹低剂量组Bmal1蛋白表达上调(P<0.05),Clock表达呈上升趋势,各剂量组Per1、Cry2蛋白表达下降(P<0.05);(5)与正常组比较,模型组大鼠Clock、Bmal1 mRNA表达量下降(P<0.05),Per1、Cry2 mRNA表达量升高(P<0.05);与模型组比较,天王补心丹各剂量组大鼠下丘脑组织中Clock、Bmal1 mRNA表达量上调(P<0.05),Per1、Cry2 mRNA表达量有所下降(P<0.05)。结论:天王补心丹改善失眠大鼠的睡眠状态,其作用机制可能与调节时钟基因反馈环路有关。

高浓度甲状腺素对软骨细胞聚集体(pellets)体外形成软骨组织的作用

目的：药物浓度（100nM）甲状腺素对组织工程软骨形成的作用。方法：将软骨细胞聚集体分为常规培养组（DMED＋10％FBS）和100nM甲状腺素组（DMED＋10％FBS＋100nM甲状腺素），体外培养1、2和3周取材进行大体形态、组织学、二型胶原和十型胶原免疫组化染色和软骨特异基因PCR分析。结果：100nM甲状腺素组形成的软骨细胞聚集体的体积和湿重均明显低于常规培养组，甲苯胺兰、二型胶原（C01II）染色较常规培养组弱，软骨细胞特异基因的表达水平与常规培养组相似，软骨细胞肥大相关基因十型胶原（ColX）及基质金属蛋白酶13（MMP13）的表达较对照组减弱，成骨方向分化相关基因（ColI，Runx2）的表达与常规培养组相似。结论：高浓度甲状腺素能够抑制软骨细胞肥大，但同时也抑制了软骨细胞增殖和软骨细胞基质分泌。

钴冶炼废渣在冶金球团中的利用及球团性能提升机理

钴冶炼废渣(钴渣)成分复杂,堆存处理会造成环境污染及资源浪费。为此提出1种以钴渣、磁铁矿和膨润土为原料制备冶金球团的新方法,研究钴渣添加量对球团综合性能及球团焙烧烟气中SO_(2)排放的影响,根据原料特性及球团矿相结构分析,揭示球团性能提升机理。结果表明:钴渣质量分数由0增至2.0%,生球落下强度由2.3次/0.5 m增至13.6次/0.5 m,生球平均抗压强度由11.5 N/mm^(2)增至14.9 N/mm^(2),添加钴渣可显著提升球团的综合性能;钴渣中S元素含量较高,钴渣的添加会造成球团焙烧烟气中SO_(2)排放浓度的增加。钴渣亲水性强,在球团原料中起到黏结剂的作用,添加钴渣有利于提升球团原料的成球性能;钴渣中含有的铁、钙、硅、铝等氧化物在球团焙烧过程中反应形成低熔点复合铁酸钙液相,适量的液相起到液相连接作用,使球团矿相结构中赤铁矿连晶更加致密,球团内部孔隙率减小,有利于提高焙烧球的抗压强度。本文研究可为钴渣在钢铁生产流程中的资源化利用提供新途径。

An Innovative Process for Direct Reduction of Cold bound Pellets from Iron Concentrate with a Coal-based Rotary Kiln

Successfully developed an innovative process of direct reduction of cold bound pellets from iron ore concentrate with a coal based rotary kiln, in comparison with the traditional direct reduction of fired oxide pellets in coal based rotary kilns , possesses such advantages as: shorter flowsheet, lower capital investment, greater economic profit, good quality of direct reduced iron. The key technologies , such as the composite binder and corresponding feasible techniques were employed in practice. A mill utilizing this process and with an annual capacity of 50 thousand ton DRI has been put into operation.

Oxidation behavior of artificial magnetite pellets

The oxidation behavior of artificial magnetite pellets was investigated through measurements of the oxidation degree and mineralogical analysis. The results show that artificial magnetite pellets are much easier to oxidize than natural magnetite. The oxidation is controlled through two different reaction mechanisms. The oxidation of artificial magnetite is dominated by internal diffusion, with an activation energy of 8.40 kJ/mol, at temperatures less than 800°C, whereas it is controlled by chemical reaction, with a reaction activation energy of 67.79 kJ/mol, at temperatures greater than 800°C. In addition, factors such as the oxygen volume fraction and the pellet diameter strongly influence the oxidation of artificial magnetite: a larger oxygen volume fraction and a smaller pellet diameter result in a much faster oxidation process.