钢铁冶炼新技术讲座之九电弧炉炼钢新技术(一)

炉外精炼是指在电弧炉、转炉之外的钢包内完成对钢水的精炼提纯任务（AOD炉不是在钢包内进行），故又可将电弧炉、转炉成为初炼炉。精炼炉始于电弧炉外的钢包精炼炉，20世纪90年代推广于氧气顶吹转炉的钢包精炼炉。     

Arcon—电转炉

电转炉是新近开发的将氧气顶吹转炉与直流电弧炉相结合的技术,其电极与顶吹氧枪可交替使用。文章介绍了电弧炉的设计及配置,并详述常用的、能用双炉壳方案实现的一种生产率高的工艺。     

南钢炼钢系统炉料结构优化工艺

研究了南京钢铁集团公司炼钢厂30t转炉和70t超高功率电弧炉的炉料配比，结果得出：减低转炉铁水比可降低金属消耗3kg/t钢，70t电弧炉铁水比为38%～40%时，电耗为230kWh/t，冶炼周期不超过60min。     

氧气炼钢领域的里程碑和挑战

回顾了氧气炼钢工艺的发展历程和10个里程碑事件,描述了自热式转炉、吹氧强度达5m3/(t·min)的高速转炉以及采用添加煤、二次燃烧和废钢比可达50%的他热式转炉,给出了相应的操作结果。介绍了一种基于铁水和铬矿的新工艺路线,304钢的生产成本可节省100美元/t以上。归纳了电弧炉和氧气转炉的结合并比较了二者的脱碳速度,介绍了优化电弧炉用氧的精炼烧嘴。展望了全球氧气炼钢的灵活性和发展前景。     

电弧炉炼钢工艺技术探讨

比较了电弧炉和转炉的炼钢方法,从工艺、效益方面深入分析了电弧炉炼钢工艺流程的技术及最新动态。     

美国的炼钢技术现状

综合介绍了美国转炉钢厂的铁水脱硫、转炉溅渣护炉的终点控制、出钢控制和钢包渣２、二镒燃烧、钢色精烧等技术,以及电弧炉钢厂的电弧炉吹氧、氧燃加热、泡沫渣操作、废钢预热、直接还原铁和电弧炉粉尘处理技术的现状和特色。     

电弧炉炼钢技术发展历史“分期”问题

提出了现代电弧炉炼钢技术发展历史的5个特点,探讨了电弧炉发展历史"分期"问题,指出:电弧炉炼钢技术100多年的发展历史,可分为传统的电弧炉炼钢技术的发生发展期、成熟期及现代电弧炉炼钢技术的发生发展期和成熟期4个阶段.现代电弧炉炼钢成熟期还将经历一个较长时间的发展阶段,但即使废钢成为电弧炉炼钢的唯一原料,在成熟期未来的时间里,电弧炉炼钢仍会保持现代电弧炉炼钢的特点,转炉和电弧炉炼钢的比例在不同时期、不同地区会有所变化,但在一个相当长的时间内,二者将共存,不会相互淘汰.     

废钢／电弧炉与高炉／转炉流程投资和成本的比较

通常，废钢／电弧炉炼钢法的投资比高炉／转炉炼钢法低２－３倍，两种炼钢法的成本高低要具体分析，评价炼钢方法要综合考虑。改造高炉／转炉法，增加废钢／电弧炉法是大势所趋。电力供应和废钢质量及价格是发展废钢／电弧炉法的限制条件。     

底吹电弧炉水力学模型实验研究

本文在实验室条件下对１０ｔ电弧炉底吹搅拌进行了水力学模研究。研究结果表明，底吹气体搅拌可大大加快溶池混匀速度，中心底吹效果较偏心底吹好，在电弧炉中底吹搅拌特性与转炉有较大偏差。     

N含量对硼钢35MnB末端淬火性能的影响

35MnB钢由40 t EAF-LF-VD-180 mm×180 mm连铸的电弧炉流程和100 t BOF-LF-RH-200 mm×200mm连铸转炉流程冶炼。35MnB钢技术协议要求J19 HRC值为33～41。试验结果表明,电弧炉流程生产的35MnB钢J19HRC值为25～28,转炉流程生产的35MnB钢末端淬火试验J19HRC值为36～41。对比分析了电弧炉流程和转炉流程生产的35MnB钢的末端淬火性能。分析得出,电弧炉流程生产的35MnB钢中的平均N含量高达(80～90)×10^-6、转炉流程为(45～50)×10^-6,电炉钢中高N含量影响了B对提高钢材淬透性的作用,为了保证钢材末端淬火性能,应控制钢中N含量≤50×10^-6。     

X90管线钢中残余奥氏体含量测量的XRD与磁性法比较

 以X90管线钢为研究对象,通过X射线衍射对其横截面、纵截面以及轧面不同位置处的残余奥氏体含量进行了分析,讨论了在不同位置处XRD残余奥氏体含量测量结果存在较大差异的原因,并就磁性法与XRD法在测量残余奥氏体含量方面的异同进行了对比。结果表明：在横截面上XRD残余奥氏体含量的测量值远远高于纵截面及轧面处;样品的横截面上存在明显的择优取向,而在纵截面、轧面处取向分布较均匀,择优取向不明显;XRD法测残余奥氏体含量受择优取向的影响较大,而磁性法不受择优取向的影响。     

Persistence of PCR-detectable Bacteroides distasonis from human feces in river water

To evaluate the persistence of PCR-detectable Bacteroides distasonis in surface water, whole human feces were dispersed into water from the Ohio River and incubated in flasks in the laboratory or in diffusion chambers in situ. Duplicate samples were taken daily, and material that pelleted at 16,000 x g was assayed by PCR. Persistence of PCR-detectable DNA from this anaerobe depended upon temperature and predation, two of the factors shown by others to influence the survival of aerobic bacteria detected by culture. B. distasonis was detected by PCR for at least 2 weeks at 4 degrees C but for only 4 to 5 days at 14 degrees C, 1 to 2 days at 24 degrees C, and 1 day at 30 degrees C. In filtered water or in the presence of cycloheximide, a eukaryotic inhibitor, persistence at 24 degrees C was extended by at least a week.     

The role of epidemiology in cancer prevention

1. ISA Brown and Shaver 288 pullets were changed from 8 h to 8, 10, 13 or 16 h photoperiods at 42, 63, 84, 105, 126 or 142 d of age. 2. Age at first egg (AFE) was curvilinearly affected by the size and timing of the change in photoperiod. AFE was advanced most by a photoperiod change from 8 to 13 h made at 63 or 84 d. ISA birds were generally more responsive than Shaver to the photoperiod changes. 3. Longer photoperiods significantly increased survivors' egg production, but decreased liveability to 504 d. so that eggs per hen housed were unaffected. Retarding AFE by 10 d reduced survivors' egg numbers by 7.0, but increased mean egg weight by 1.26 g. Egg output by Shaver birds was unaffected by AFE, but that of ISA was curvilinearly affected, with an apogee at an AFE of 135 d. In both breeds, egg weight and egg output were greater following an early or late, rather than a mid-term photostimulation. 4. Photoperiod significantly increased mean daily food intake during lay by 1.26 g/h. A 10 d retardation in AFE resulted in a reduction in food intake of 1 g/d. Efficiency of food conversion deteriorated according to the square of the photoperiod, and changed curvilinearly according to age at photostimulation. Food conversion efficiency improved by 0.05 g/g for each 10 d delay in AFE. 5. Shell quality was unaffected by AFE, but deteriorated with increasing photoperiod and was curvilinearly affected by age at photostimulation with the smallest shell weights associated with photostimulation at 63 d. The incidence of double-yolked (DY) egg production increased with photoperiod and decreased with delayed photostimulation. There was an exponential regression of DY eggs on AFE. 6. Body weight at first egg increased by 75 g/d delay in AFE, but body weight at 504 d of age was unaffected by AFE, photoperiod or age at photostimulation. Body weight gain during lay increased by 15 g/h increase in photoperiod, decreased by 6 g per 10 d delay in photostimulation and by 40 g per 10 d delay in AFE. Fat content at 504 d increased by about 10 g/kg and by 23 g/bird for each 10 d delay in AFE. 7. Mortality in lay increased by 0.8%/h increase in photoperiod, but was unaffected by either age at photostimulation or AFE.     

Coefficient of Friction Measured from Nano- to Macro-Normal Loads on Plasma Sprayed Nanostructured Cermet Coatings

Alumina dispersed FeCuAl-based nanostructured cermet coatings were deposited from nanostructured powders by atmospheric plasma spraying on low carbon steel substrates. Nanostructuring was retained in the deposited coatings which exhibit up to four distinctive phases as revealed by electron microscopy. In this study, the friction behavior of the distinctive phases at nano-normal load scale was investigated alongside their contribution to the overall friction behavior at macro-normal load scale. Friction behavior at nano-normal load scale was investigated by lateral force microscopy, whereas conventional tribometers were used for investigations at micro and macro-normal loads. It appeared that, the friction measured at nano-normal loads on individual phases is dictated by both composition and hardness of the corresponding phases, and thus influences the overall friction behavior of the coatings at macro-normal loads. Moreover, the coefficient of friction at macro-normal loads differs from the one at nano-normal loads, and deviates from Amonton’s friction law.     

Effects of genistein and lavendustin on reproductive processes in domestic animals in vitro

The aim of our experiments was to study the influence of genistein [tyrosine kinase (TK) inhibitor with estrogenic activity] and lavendustin A (TK inhibitor without estrogenic activity) on female reproductive processes in domestic animals in vitro. It was found that genistein (0.001-1 microg/ml) increased IGF-I release by cultured bovine and porcine granulosa cells, but decreased its secretion by rabbit granulosa cells (0.01-10 microg/ml). Genistein stimulated progesterone secretion by bovine and rabbit granulosa cells (at 0.01-10 microg/ml), estradiol output by rabbit granulosa cells (at 1 microg/ml) and porcine ovarian follicles (at 10 microg/ml), as well as cAMP production by bovine (at 0.001-1 microg/ml) and rabbit (at 1 microg/ml) granulosa cells. No effects of genistein (at 10 microg/ml) on PGF-2 alpha and progesterone release by porcine ovarian follicles were observed. Genistein significantly (P < 0.05) stimulated the reinitiation and completion of nuclear maturation of porcine oocytes (at 5 microg/ml), as well as the preimplantation development of rabbit zygotes (at 1 microg/ml). Lavendustin A (0.001-1 microg/ml) increased IGF-I release by bovine (but not by porcine) granulosa cells, cAMP release by bovine granulosa cells, and PGF-2 alpha output by porcine ovarian follicles (at 10 microg/ml). Lavendustin (at 1 microg/ml) had no significant effect on IGF-I release by porcine granulosa cells, on estradiol and cAMP output by rabbit granulosa cells, or on progesterone secretion by porcine follicles (at 10 microg/ml). Inhibitory actions of lavendustin (at 10 microg/ml) on estradiol secretion by porcine follicles were also found. Furthermore, lavendustin, like genistein, promoted the reinitiation and completion of meiosis in porcine oocytes. The present study demonstrates a predominantly stimulatory effect of TK inhibition on endocrine and generative processes in domestic animals. The majority of these effects are similar for both compounds, indirectly suggesting that their action is due to tyrosine kinase inhibition and protein kinase A-stimulation, rather than estrogenic activity.     

Strategies for coping with work-family conflict: The distinctive relationships of gender role ideology.

Study 1, with 266 employed parents, identified 8 coping strategies: super at home, good enough at home, delegation at home, priorities at home, super at work, good enough at work, delegation at work, and priorities at work. Study 2, with 679 employed parents, demonstrated a moderating effect of sex and gender role ideology in the relationship between coping strategy and work-family conflict. Specifically, the relationships between coping strategies (i.e., good enough at home, good enough at work, and delegation at work) and work interference with family were moderated by sex and gender role ideology. Regarding family interference with work, the relationships between coping strategies (i.e., good enough at home and good enough at work, delegation at home and delegation at work, and priorities at home) and family interference with work were moderated by sex and gender role ideology. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Longitudinal study of bowel and bladder control by day and at night in the first six years of life. I: Epidemiology and interrelations between bowel and bladder control

The development of bowel and bladder control by day and at night during the first six years of life in 320 Swiss children in the Zurich longitudinal study (1955--1976) is described in detail. A scoring system was used which included intermediate stages of control. With toilet-training started in 96 per cent of the children during the first year of life, bowel control was completed in 32 per cent at age one, in 75 per cent at age two and in 97 per cent at age three. Complete bladder control by day and at night were established in none of the children at age one, in 20 per cent at ages two and three and in 90 per cent at age four. Complete bowel control and complete bladder control by day and at night were found in 5 per cent at age two, in 11 per cent at age three, in 77 per cent at age four and in 91 per cent at age six. The significant relationships between bowel control, bladder control during the day and bladder control at night (p less than 0-001) demonstrate that the same developmental process acts in bowel and bladder control. Highly correlated to each other, first bowel control develops, then bladder control by day and finally bladder control at night. The relevance of these interrelations for toilet-training and for the management of enuretic and encopretic children is discussed.     

Effect of compression temperature on the consolidation mechanism of chlorpropamide polymorphs

The effect of environmental temperature on the compression mechanism of chlorpropamide (CPM) polymorph, forms A and C, was investigated with an eccentric type tabletting machine with two load cells and a noncontact displacement transducer. The temperature of the die was controlled at 0 and 45 degrees C by a thermocontroller. Sample powders (200 mg), which were also controlled at 0 and 45 degrees C by a thermocontroller, were compressed at almost 230 MPa. The tabletting dynamic processes of CPM forms A and C at 0 and 45 degrees C were evaluated by Cooper and modified Heckel analyses. The results suggest that particle brittleness or plasticity was affected by compression at different temperatures. The higher tablet hardness of form A at 45 degrees C was thought to be caused by the increased plasticity of primary particles, whereas that of form C at 45 degrees C was ascribed to the decreased size of the secondary particles.     

Relative roles of testosterone and the germ cell complement in determining stage-dependent changes in protein secretion by isolated rat seminiferous tubules

This study has compared the effect of withdrawal of testosterone (+/- replacement) with that of selective depletion of pachytene spermatocytes (PS) or round/elongating spermatids (RS), or both PS and RS, on the level of overall protein secretion by seminiferous tubules (ST) isolated at particular stage-groups of the spermatogenic cycle. Testosterone withdrawal was induced by destroying the Leydig cells with a single injection of ethane-dimethane sulphonate (EDS), with or without concomitant replacement of testosterone by injection; ST at stages II-V, VI-VIII or IX-XII were then isolated from control and treated rats at 4 days after treatment. Methoxyacetic acid (MAA) was administered, in either one or two doses, to selectively destroy 80-100% of pachytene and later spermatocytes; ST at stages I-V, VI-VIII or IX-XIV were then isolated at specific times after treatment such that ST were depleted selectively of either PS, RS or PS+RS. Isolated ST (5 cm) were then cultured for 22 h at 34 degrees C with 35S-methionine and its incorporation into secreted proteins then quantified. Based on the incorporation of 35S-methionine, ST at stages VI-VIII showed a significantly higher level of protein secretion than did ST at earlier or later stages. This difference was abolished following testosterone withdrawal but was maintained by testosterone replacement. The normal increase in protein secretion by ST at stages VI-VIII was also prevented if either PS or RS were depleted, whereas depletion of either PS or RS alone had no significant effect on protein secretion by ST at stages I-V, and only the depletion of RS significantly reduced protein secretion by ST at stages IX-XIV. Depletion of both PS+RS reduced protein secretion significantly by ST at all stages. In contrast to the data for total protein secretion, the levels of sulphated glycoprotein (SGP)-1 and SGP-2 secreted by ST at stages VI-VIII showed that these two Sertoli cell proteins were unaffected by germ cell depletion except after co-depletion of PS+RS when secretion of SGP-1 was halved.(ABSTRACT TRUNCATED AT 400 WORDS)     

Body weight and body composition changes after treatment of hyperthyroidism

Body composition changes in nine adults with hyperthyroidism were determined with dual energy x-ray absorptiometry and computed tomography at diagnosis and after 3 and 12 months of euthyroidism achieved by surgery, antithyroid drugs, or treatment with radioiodine. Mean body weight was 67.6 kg at diagnosis and increased 2.7 kg (P=0.06) and 8.7 kg (P < 0.001) after 3 and 12 months of euthyroidism, respectively. Basal metabolic rate decreased from 2087 Cal/24 h at diagnosis to 1601 Cal/24 h at 12 months (P=0.001), whereas reported energy intake dropped from 3244 to 2436 Cal/24 h (P=0.01). According to dual energy x-ray absorptiometry, body fat was unchanged at 3 months, but increased by 5.3 kg (P < 0.0001) at 12 months. Fat-free mass increased 2.7 kg (P=0.003) at 3 months and 3.5 kg (P < 0.0001) at 12 months. Changes in bone mineral content and density did not reach significance. According to computed tomography, skeletal muscle plus skin areas increased by 11% (trunk) and 18% (thigh) at 3 months and by 17% (trunk) and 25% (thigh) at 12 months. There was no increase in sc adipose tissue (AT) at 3 months, but at 12 months this AT depot increased by 15% (thigh) and 33% (trunk). Intraperitoneal AT showed a borderline significant increase by 28% (P=0.08) at 3 months and by 40% (P=0.015) at 12 months. Areas of visceral organs and bone tissue of femur did not change significantly during the study. It is concluded that during early recovery from hyperthyroidism, priority is given to the replenishment of skeletal muscles and ip AT, whereas sc AT is increased at a later stage.