宝钢3号高炉实现高利用系数技术研究

宝钢3号高炉通过生产攻关，实现高利用系数冶炼，实际利用系数最高达到2．427。重点研究了不同生产条件下，高利用系数冶炼生产技术，特别分析了在原燃料恶化的条件下，实现高利用系数的生产技术，并进行理论分析和研究，为高炉进一步实现高利用系数提供依据。     

宝钢4号高炉高利用系数低燃料比生产实践

对宝钢4号高炉高利用系数低燃料比生产实践进行了总结.针对宝钢4号高炉进入炉役中期后面临的一系列问题,通过采取比较系统的综合优化措施,诸如保持较高的煤气利用率操作、较低且稳定的热负荷操作,以及封堵炉体和炉缸气隙等,4号高炉逐步实现了高利用系数低燃料比生产.2020年,4号高炉最高月均利用系数达到2.477,最低月均燃料比...     

迁钢2号高炉180kg／t高煤比攻关实践

对迁钢2号高炉180kg/t煤比的工业试验进行了总结.通过采取改造喷煤设备、改善原燃料质量、优化高炉操作制度、加强炉外管理等措施,2号高炉高煤比攻关达到了预期目的,高炉富氧率达到4%,利用系数达到2.53,煤比达到180.35 kg/t.     

太钢4350高炉喷煤比突破200kg／t大关

2007年9月份，太钢炼铁厂4350高炉生产取得优异成绩，高炉利用系数、生铁含硅量、高炉喷煤比均创历史最好水平。煤比持续上升，突破了200kg／t大关，达到203kg／t；截至9月27日，全月日均产铁超万吨，达到了10047t，利用系数达到了2．31；铁水含硅量由1～8月的0．51％降低为0．42％，     

马钢2 500 m3高炉高利用系数条件下提高煤比的技术研究

马钢 2 5 0 0 m3高炉通过不断提高操作技术水平 ,改善原燃料条件 ,加强基础管理 ,2 0 0 1年在维持13 0 kg/ t煤比条件下 ,实现年平均利用系数 2 .3 13 t/ (m3· d)。 2 0 0 2年在继续保持稳产高产的同时 ,通过技术攻关 ,大力提高煤比 ,创造了月平均利用系数 2 .5 74t/ (m3· d) ,煤比 15 2 kg/ t的历史新高 ,达到了国内同类型高炉先进水平     

从实践看昆钢6号高炉的炉体设计

昆钢6号高炉投产后生产技术指标较好，2001年一季度利用系数达到2．170，人炉焦比降低到387kg/t，煤比达到130.4kg/t,这与高炉炉体的合理设计有很大的关系。     

太钢二高炉生产工艺技术的进步

太钢2号高炉自1999年5月采取高炉槽下过筛,提高风温,富氧喷吹及加强高炉操作等措施,高炉技术经济指标大幅度提高,利用系数连续4个月达到2．8以上,入炉焦化降至404kg／t,煤比达130kg/t跻身于全国同类型高炉前列。     

莱钢喷煤技术进步

分析了莱钢高炉喷煤特点，通过采取改善原燃料条件，加强高炉操作，提高风温等措施，莱钢750m^3高炉煤比达到了180kg／t，高炉利用系数达2．7。     

武钢2号高炉生产操作实践

对武钢2号高炉生产操作进行了总结,指出了今后生产操作需要解决的问题。2号高炉大修改造投产后,不断改进和优化高炉操作,使主要技术经济指标取得了较大进步,2001年上半年利用系数达达到2．002,入炉焦比降至403．2kg/t,煤比113．3kg/t.     

安钢2#高炉富氧喷煤实践

安钢２＃高炉１９９６年煤比为５０ｋｇ／ｔ,近几年来,通过采取一系列措施,如改进喷煤设备和工艺,改善原燃料条件,改进高炉操作等,煤比逐年提高,１９９９年利用系数达到２．７３ｔ／ｍ３ｄ;焦比达到４５５ｋｇ／ｔ煤经达到１２４ｋｇ／ｔ。     

Smoking: high hazards in high school

BACKGROUND: Young people in school are at an impressionable age, peer pressures are intense, and the probability that they will pick up a high-risk behavior, such as smoking, is high. The key to reduction of smoking among adults is to target our prevention efforts at young adults and teens. OBJECTIVE: To study the prevalence and trend of smoking among young adults and teens and to formulate guidelines on smoking reduction to guide those who counsel young people. STUDY DESIGN: The study design is cross sectional. METHODS: This study is based on the data from the Oklahoma Behavioral Risk Factor Surveillance System and the National Youth Risk Behavioral Surveillance System - the two systems that monitor the prevalence of behaviors that most influence health. RESULTS: The prevalence of smoking among young adults (age 18-24) in Oklahoma is high at more than 21%. The disturbing feature is that it is higher among young females than among young males. The prevalence of smoking among young adults is the highest among high school dropouts and is more than 38%. It is lower among high school graduates (about 28%) and lowest among college graduates (about 18%). The percentage of smoking among students who classify themselves as current smokers rises from 23% to 30% as the students progress from grade 9 to 12 and the percentage of frequent smokers increases from 8% to 16%. CONCLUSIONS: Guidelines suggested for counselors are: 1. Along with smoking, look for comorbid behaviors such as alcohol use, drug abuse, and high-risk sexual behavior. 2. Ask whether the student has easy access to free cigarette samples. 3. Check whether the teen is trying to lose weight; suggest appropriate methods for losing weight if smoking is being used for losing weight. 4. Target health education efforts early in a student's school career starting in elementary school, but concentrate especially at the 8th or 9th grade level to have maximum preventive impact.     

The high temperature transformation of high speed steel

Low tempered hardnesses on high speed steels which had been hardened in vacuum or atmosphere furnaces and gas quenched led to a search for a reaction occurring above 1400°F and probably initiated as a result of the slower cooling rate of the gas quench. A standard TTT evaluation was carried out on Ml, M2 high carbon, M3, and M7 high speed steels, quenching from conventional hardening temperatures, into salt baths maintained at 2000° to 1500°F. Examination of these specimens indicated the presence of a reaction occurring at all temperatures investigated but having its maximum rate at 1700° to 1800°F. The reaction involved precipitation of an MoC/Mo₂C carbide at grain boundaries and within the grains, with the amount of precipitate increasing with time. The precipitation of MoC/Mo₂C is directly related to the loss in tempered hardness and apparently causes this effect by 1) reducing precipitation hardening on tempering, 2) drastically lowering retained austenite contents, and 3) reducing as-quenched hardnesses.     

高综合性能亚共晶高铬铸铁的烧结制备

以气雾化粉末为原料,采用液相烧结(LPS)制备亚共晶高铬铸铁(HCCIs),系统研究烧结工艺参数对致密化行为、显微组织演变和力学性能的影响规律。研究结果表明,采用LPS可以获得相对致密度达99%以上的制品,但合适的烧结温度范围很窄;XRD分析表明烧结亚共晶高铬铸铁由M7C3型碳化物、马氏体和奥氏体构成;金相分析显示烧结样晶粒细小,碳化物为一次晶杆状,且分布均匀。随烧结温度升高和保温时间延长,晶粒和碳化物均逐步粗化,其中温度的影响更加显著;而强度和冲击韧性则呈现先升高后降低的变化规律。优化的烧结工艺下高铬铸铁的力学性能为：硬度HRC65,抗弯强度1199 MPa,冲击韧性4.6 J/cm2。并提出了一个烧结高铬铸铁中碳化物形态演变的生长模型。     

MgO对高碱度高铝烧结矿的影响

 随着钢铁企业高铝铁矿粉使用比例的提高,带来了高炉炉渣黏度增大、渣铁分离困难等一系列问题。采用烧结杯试验,研究了MgO含量增加对高碱度高铝烧结矿经济技术指标、冷强度和冶金性能的影响,采用Nova400 NanoSEM型场发射扫描电子显微镜分析了烧结矿微观结构。试验结果表明,高碱度高铝烧结矿中MgO质量分数从1.72%提高到2.49%时,垂直烧结速度降低4.38 mm/min,利用系数降低0.51 t/(m2·h),低温还原粉化指数增加6.7%;当烧结矿中MgO质量分数为2.11%时,转鼓指数和还原度最高,分别达到61.93%和86.39%;Mg2+主要固溶在磁铁矿晶格中并替代Fe2+,替代的质量分数最高达3.64%,生成的含镁磁铁矿抑制烧结矿降温过程中由Fe₃O₄→Fe₂O₃氧化过程的相变,减少了二次赤铁矿的生成,有利于改善烧结矿的低温还原粉化性能。研究结果可以为改善高碱度高铝烧结矿性能和提高炉渣流动性提供理论指导和参考依据。     

高碳钢高温力学性能研究

在Gleeble-2000动态热模拟试验机上采用凝固法研究了高碳钢的高温力学性能.测定了tZD(零塑性温度)、tZS(零强度温度).在4×10-4/s应变速率条件下,所测钢种在熔点到750 ℃范围存在两个脆性温度区域,即熔点到1 300 ℃的第Ⅰ脆性温度区域和750～925 ℃的第Ⅲ脆性温度区域.在第Ⅲ脆性温度区域,γ单相AIN、NbN等氮化物在γ晶界的析出和在γ α两相区先共析α相呈网膜状,在γ晶界的析出是造成钢脆化的主要原因.通过控制钢中氮、铝含量,以及采用合理的冷却方式可以提高钢种的内在质量.     

Demanganisation of high manganese pig iron to produce high manganese slag

Abstract

Pig iron with a high manganese content makes further processing to steel using converter technology difficult and unprofitable. In the present study, external demanganisation of high manganese pig iron before the oxygen converter process has been investigated. Pilot plant experimental heats were designed and carried out to optimise the demanganisation process, to produce hot metal adequate for the conventional LD converter, and high manganese slag suitable for the production of silicomanganese. Various high manganese pig irons with different [Si]/[Mn] contents were treated by injection of various oxidisers at varying temperatures, slag basicities and injection rates. The optimum conditions for the demanganisation process have been attained by injection of an oxygen gas–manganese ore mixture at the injection rate of 6.8 L min^-1kg^-1 into molten high manganese pig iron with a [Si]/[Mn] ratio of 0.3 at an initial temperature of 1350°C and slag basicity of 0.3–0.4.     

Microstructure characteristics of spray-formed high vanadium and cobalt high speed steel

The microstructure of high vanadium and cobalt high speed steel(high-V/Co HSS) and the morphology of its carbides were analyzed by optical microscope(OM),scanning electron microscope(SEM),electron probe microanalysis(EPMA),X-ray power diffraction(XRD),atomic force microscopy(AFM) and single phase erosion(SPE).The results suggest that the as-sprayed high-V/Co HSS has fine equiaxed grains(about 20 μm in size),which were homogeneously distributed.The carbides have two classical morphologies:one is fine particles(about 2 μm in size) distributed along the grain boundaries and the other is needle-like one,distributed on the grain boundaries.There are MC carbides,M2C carbides,M6C carbides and Cr2WC2 carbides in the as-sprayed high-V/Co HSS samples,however,in the as-cast high-V/Co HSS,there are MC carbides and Cr2WC2 carbides only.The SPE results show that there are two types of MC carbides in the as-sprayed HSS:the sphere one and the particle-like one.The former is about 2 μm in size and the latter is less than 1 μm,dispersed inside the grains,quite different from the MC carbides in the as-cast HSS.According to the AFM results,the skeleton-like M6C carbides of the as-sprayed high-V/Co HSS are embedded in the matrix along the grain boundaries.It is found that there are sharp membrane pieces on the carbides.Some small bamboo-shoot-like MC carbides grow from the matrix and are dispersed inside the grain.Those larger MC carbides are spherical particles embedded at the grain boundary junctions.     

CNS tumours in south-western Finland: high location, high incidence

The Department of Paediatrics at the University Central Hospital of Turku, Finland has 130,000 children under 17 y of age within its catchment area. We collected all 103 cases of newly diagnosed CNS tumours from the 15-y period of 1981-95. The incidence was 5.3:100,000, a figure twofold those usually presented. During the period 1981-85 the incidence was lower (4) than during the subsequent 5-y periods (5.7 and 6.2). There were no statistical differences between the incidences of the supra- vs infratentorial brain tumours. Optic glioma was unusually common (17%, CI 13.9-20%).     

Tubeless superimposed high frequency jet ventilation in high grade laryngeal stenoses

Massive stenosis of the larynx may present a potentially life-threatening situation for the patient, requiring immediate measures to ensure a patient's airway. The aim of this prospective study was to evaluate potential benefits of Superimposed High Frequency Jet Ventilation (SHFJV) in patients requiring microlaryngeal surgery due to massive stenosis of the larynx. Patients and methods: 23 patients (age range 1.5 to 90 years) with laryngeal stenosis grade 2 and 3 according to the Cotton scale were ventilated using SHFJV. The duration of the SHFJV was 12 to 116 minutes. SHFJV was performed using a Bronchotron Respirator via a jet-laryngoscope. Results: Arterial blood gases demonstrated paO2 between 71 and 295 mmHg and paCO2 of 28 to 81 mmHg. The mean FiO2 applied was 61.75 +/- 19.26. The airway pressure was measured at the tip of the jet-laryngoscope and was between 6 and 15 mmHg, and PEEP was 1 to 5 mmHg. In 13 patients a CO2 laser was utilised during surgery. Discussion: In all patients SHFJV was performed without problems. Since the ventilation is delivered above any possible stenosis the danger of barotrauma is minimised. The surgeon obtains optimal visibility of the larynx and is not obstructed in the surgical procedure. SHFJV enables both the surgeon and the anesthetist to perform their respective duties and therefore increases the safety of the patient in the management of such a difficult problem as massive stenosis of the larynx.     

Recent developments of the high strength and high ductility nanostructured materials

This talk will summarize the recent work related to a kind of new nanomaterials produced by the SMAT (surface mechanical attrition treatment).The concept of surface nanocrystallization of materials will be presented.In terms of the grain refinement mechanism induced by plastic deformation,a novel surface mechanical attrition(SMA) technique was developed for synthesizing a nanostructured surface layer on metallic materials in order to upgrade the overall properties and performance.The grain refinement mechanism of the surface layer during the SMA treatment will be analyzed in terms of the nanostructure observations in several typical materials.Very high yield stress(5 times of the base material) on the surface layer of the material obtained by the SMAT has been observed.The effect of surface nanostructures on the mechanical behavior and on the failure mechanism of metallic material shows the possibility to develop a new strength gradient composite using co-rolling and nitriding.The role of residual stress induced during the treatment will be investigated and discussed.The developed materials are also porosity free materials which can be used as reference material for the local mechanical behavior investigation technique such as the nanoindentation.A general concept for obtaining high strength and high ductility nanostructured materials will be presented.The exceptional high strength and high ductility steels have developed.The simulation of the mechanisms for improving ductility of high strength nanostructured materials will be presented.The potential applications for the land transportation vehicles(car,bus,train) and wind energy have been investigated.Some examples of concept design for the integration of the advanced nanostructured steels will be presented.