生产58%铁品位烧结矿的技术探索实践

提高烧结矿品位不但可以降低高炉渣量和高炉燃料比,同时可促进高炉的稳定顺行,是高炉精料方针的关键之一。在坚持铁矿粉烧结性能互补配矿的前提下,在分析烧结矿化学成分对烧结矿产质量影响的基础上,探讨了各元素适宜的控制范围;通过优化烧结矿化学成分,降低烧结矿中SiO_2、MgO、Al_2O_3含量,控制合适碱度,同时配合适宜的工艺参数和操作制度,烧结矿品位稳定保持在58.00%以上,最高月份达到58.60%。烧结、高炉生产实践表明:提高烧结矿品位后,烧结矿主要质量指标(强度、成品率、粒度等)得到改善;烧结矿品位提高0.58%～0.71%,高炉入炉品位提高0.37%～0.45%,渣比降低10.54～10.67 kg/t,燃料比降低1.73～5.29 kg/t,能很好满足高炉冶炼要求,促进了高炉炉况稳定和生产顺畅。     

80%外矿高碱度烧结矿炼铁生产实践

通过充分的技术准备和及时准确的高炉操作调整，在配加80％的外购矿高碱度烧结矿炼铁工业试验中，包钢炼铁厂取得了高炉技术经济指标的巨大飞跃。高炉利用系数达到2．063t(m3．d)以上，最高2．202t(m3．d)，焦比下降27．5kg/t，综合焦比下降15.0kg/t。证明了增加外来矿配比是改善包钢烧结矿特殊性，提高高炉技术经济指标的有效途径。     

烧结矿喷洒CaCl2溶液试验研究及工业应用

针对烧结矿低温还原粉化率偏高的现状,进行了喷洒CaCl2溶液试验,研究结果表明,烧结矿喷洒CaCl2溶液在溶液浓度为3％时,效果最佳,烧结矿低温冶金性能有明显改善。高炉工业生产显示,烧结矿喷洒CaCl2溶液后,高炉利用系数提高0．1t/m^3．d,入炉焦比降低5kg／t。     

烧结使用块矿铺底料的生产实践

龙钢烧结使用块矿替换烧结矿作铺底料的试验表明:块矿替代烧结矿作铺底料有利于提高烧结生产率,降低烧结能耗,改善烧结矿强度和低温还原粉化指标,进而优化炼铁高炉炉料结构。含块矿烧结矿配比入炉率达到75%以上,大量使用块矿,使高价位外购球团矿使用量减少。同时高炉铁水含硅量、燃料比大幅度降低,1号、2号高炉吨铁燃料比较前下降了63.73kg,3号、4号高炉吨铁燃料比较前下降了75.98kg,生铁成本降幅在100元左右,高炉各项经济技术指标也大幅提升。     

超厚料层双层预烧结工艺研究与工业试验

超厚料层烧结可提高烧结矿成品率和转鼓强度,降低烧结固体燃料消耗和污染物排放,代表铁矿烧结的发展方向。但当烧结料层厚度超高700 mm时,烧结矿产率会下降。为此,本文对双层预烧结新工艺进行了一系列研究,结果表明:双层预烧结新工艺可明显提高烧结矿产率,提产效果明显,但烧结矿转鼓强度有一定程度下降,其主要原因是烧结过程料层下部缺氧;通过适当延长预烧结时间,可缓解料层下部缺氧问题,明显提高烧结矿转鼓强度。在鞍钢炼铁总厂二烧车间360 m~2烧结机和4、5号高炉开展近7个月双层预烧结工业试验,烧结矿增产16.11%,高炉顺行情况良好,高炉利用系数、燃料比及风量与基准期基本一致,表明双层预烧结新工艺在生产实践上完全可行。     

硼铁精矿作为造块节能添加剂的试验研究

在首钢球团厂和烧结厂分别进行了配加硼铁矿粉的工业试验,结果表明:球团配加3%的硼铁矿粉后,在焙烧温度降低11 ℃的情况下,成品球抗压强度仍提高223 N/个,具有一定的节能效果;烧结配加相同比例的硼铁矿粉后,燃耗降低,烧结矿强度提高,粒度组成改善,高炉配用40%含硼烧结矿后,炉况顺行,综合焦比降低5.53 kg/t,节能效果较为显著.通过烧结杯试验进一步摸索了硼铁矿的适宜配比和节能效果,结果认为,烧结厂配加1%～5%的硼铁矿粉可降低燃料消耗0.96～2.83 kg/t,提高利用系数0.01～0.15 t/(m2·h);烧结配加3%硼铁矿粉可达到最佳的节能效果.     

润磨强化镜铁精粉烧结特性的研究

巴西镜铁精粉难制粒反应性差,通过润磨单一镜铁矿或其与石灰石的混合料可改善其表面性质和高温反应性能.测定润磨预处理前后巴西镜铁矿的润湿热、粒度组成及变形温度等指标,揭示其作用机理.并通过烧结杯试验,考察润磨预处理强化烧结的效果.研究结果表明,润磨改善了巴西镜铁矿的润湿热,表面亲水性得到改善;降低了变形温度,提高了巴西镜铁矿的高温反应性能.巴西镜铁矿预处理后,烧结矿产量和质量得到大幅度改善,成品率增加了3.7%,转鼓强度提高了3.33%,固体燃耗降低了约4 kg/t ,利用系数提高22.4%,烧结矿质量完全能满足高炉生产的需要.     

攀成钢烧结配加高炉瓦斯灰工业试验

介绍了在攀成钢2×28.5 m2烧结机原燃料条件及生产设备条件下,用高炉瓦斯灰部分取代焦粉作为烧结燃料的工业性试验情况.结果表明:在28.5 m2烧结机系统情况下,配加1%的高炉瓦斯灰,烧结矿固体燃料消耗下降4.75 kg/t,而烧结机利用系数、烧结矿品位、烧结矿FeO含量、烧结矿转鼓指数和筛分指数没有明显变化.因而充分利用了炼铁二次资源,对缓解炼铁厂焦粉紧张、外购困难以及实现循环经济具有较大的实际意义.     

湘钢改善烧结矿质量的生产实践

介绍了湘钢烧结厂近几年通过抓原料管理、电子秤改造、配加生石灰、采用小球烧结工艺 ,优化烧结配料等措施 ,使烧结矿质量明显改善 ,从 1998～ 2 0 0 1年烧结矿合格率提高 3 2 % ,转古强度提高 3 .2 % .高炉使用该烧结矿后 ,利用系数提高 1.114t/ (m3·d) ,焦比下降 2 12 .6kg/t.     

TiO_2含量和碱度水平对钒钛烧结矿成矿规律的影响研究

为了考察不同TiO_2含量和碱度水平对钒钛烧结技术经济指标和钒钛烧结矿冶金性能的影响,以便确定更优的烧结和高炉物料结构,为此开展了降低烧结矿TiO_2含量,同时提高烧结矿碱度水平的试验研究。研究表明:随着钒钛烧结矿TiO_2含量的降低和碱度水平升高,烧结矿各项技术指标明显改善,当烧结矿中TiO_2含量从6.0%降低至0.5%,碱度水平从2.0提高至2.5时,成品率提高5.21个百分点,转鼓强度提高5.60个百分点,利用系数较基准期提高25%以上。     

50%

摩根士丹利、煤林和麦格理银行等金融机构预测,2008年度铁矿石长期合同价格将上涨50%,这是目前媒体上所能看到的涨幅的最高预测。摩根大通则认为2008年铁矿石价格将上涨30%,而 JP 摩根的预期涨幅为25%～30%。与金融机构和各利益相关方的百家争鸣相反,身处漩涡中心的各方谈判     

Precipitation behaviour of 25% Cr - 5.5% Ni austenitic stainless steel containing 0.87% nitrogen

In this paper, a 25Cr - 5.5Ni steel (mass contents in %), which originally had a ferritic-austenitic duplex microstructure (DIN material no. 1.4460), and to which mass contents of 0.87% nitrogen were added to become fully austenitic was studied. The phase transformations that occurred between 700 and 1350°C were studied using several complementary techniques. Firstly, various treatments were carried out in the range 1050-1350°C for 1h to select the best temperature for solution heat treatment. Chromium nitride dissolution and absence of ferrite were was observed at 1250°C for 1h. Subsequently, the specimens were aged in the range 700-1100°C, for 90s up to 100h. The first phase to precipitate was chromium nitride. Ferrite precipitation occurred after long aging times, followed by sigma phase precipitation. A TTT diagram has been proposed.     

Volumetric deformation of Al-4.4% Cu and Al-4.4% Cu-0.5% Mg compacts during sintering

Conclusions Formation of intermetallics with heating of compacts is accompanied by an exothermic effect as a result of which the temeprature for eutectic melting of a specimen (548°C) is achieved sooner than in the surrounding volume. The magnitude of the corresponding temperature drop depends on copper content and it is 5°C for Al-4.4% Cu, and for Al-50% Cu it is 23°C. Introduction of 0.5% magnesium into Al-4.4% Cu alloy reduced the temperature for melt formation as a result of appearance of a more readily melting ternary eutectic.Growth of Al-Cu and Al-Cu-Mg compacts during sintering in the solid solution region of the composition diagram is caused by diffusion impregnation. With sintering in the liquid-solid region of the diagram apart from diffusion impregnation compact growth is affected by spreading of melt over the surface and grain boundaries of aluminum particles whose relative contribution to the overall compact growth is about 30%. Compacts of Al-4.4% Cu-0.5% Mg increase to a greater extent than for Al-4.4% Cu, which is caused by an increase in their liquid phase content.Translated from Poroshkovaya Metallurgiya, No. 2(350), pp. 13–17, February, 1992.     

Heat treatment and properties of plastically deforming, highly coercive iron alloy (30% Cr, 15% Co, 2% W, 1% Mo, and 1% Ti)

The structural transformations of plastically deforming, highly coercive Kh30K15V2MT iron alloy (30% Cr, 15% Co, 2% W, 1% Mo, and 1% Ti) are studied, along with its magnetic and mechanical properties. Metallographic and X-ray data show that, besides the α solid solution that exists at 1220–1180°C, metastable α phase is present at 670–700°C. If the alloy is annealed at 670–700°C after cold deformation, no recrystallization occurs; only processes of recovery and polygonization are observed. The relation of the magnetic and mechanical properties to the initial state and structure of the single-phase α solid solution is established. Either good magnetic properties or good mechanical properties may be obtained, by adjusting the initial state of the single-phase α solid solution.     

Eigenschaften elektroschlackegeschweißter Verbindungen eines Stahles mit rd. 0,25% C, 1,5% Cr, 0,5% Mo, 3% Ni und 0,2% V nach dem Schmieden mit geringem Umformgrad

Herstellung elektroschlackegeschweißter Verbindungen von Proben aus einem Stahl mit 0,26% C, 0,59% Mn, 1,64% Cr, 0,46% Mo, 3,18% Ni und 0,19% V mit weitgehend artgleichen Elektroden. Prüfung der mechanischen und magnetischen Eigenschaften des Schweißgutes im unverformten und verformten Zustand. Untersuchung des Gefüges in der wärmebeeinflußten Zone und im Schweißgut.     

0.45% saline and 5% dextrose in water, but not 0.9% saline or 5% dextrose in 0.9% saline, worsen brain edema two hours after closed head trauma in rats

In this study, we examined the effect of four i.v. fluids (250 mL/kg) on blood glucose and osmolality and brain tissue specific gravity after closed head trauma (CHT) in rats. CHT was delivered at Time 0; blood was sampled at 60 min; fluid infusion began at 75 min and ended at 105 min. Blood was again sampled at 105 and 120 min, and brain tissue specific gravity was determined at 120 min. Five groups (one control and four fluid-treated groups) received CHT, and five other groups (one control and four fluid-treated) did not (n = 9 in each group). 0.45% saline (1/2 NS) and 5% dextrose in water (D5W) accentuated the decrease of brain tissue specific gravity (1.0366 +/- 0.0025 and 1.0368 +/- 0.0028, respectively; mean +/- SD) caused by CHT (1.0395 +/- 0.0036), but 5% dextrose in 0.9% saline (D5NS) and 0.9% saline (NS) did not (1.0431 +/- 0.0042 and 1.0389 +/- 0.0049, respectively). In addition, 1/2 NS decreased blood osmolality (248 +/- 6 mOsm/L), D5W increased blood glucose (1095 +/- 173 mg/dL), D5NS increased blood osmolality (350 +/- 5 mOsm/L) and glucose (1695 +/- 76 mg/dL), and NS caused no significant change. We conclude that administering hypoosmolar i.v. fluids after CHT causes a significant worsening of cerebral edema 2 h after CHT. Implications: We previously reported worse neurological outcome and/or mortality after closed head trauma in rats when 5% dextrose in water or 0.45% saline was given i.v. compared with 0.9% saline or 5% dextrose in 0.9% saline. The present results and our previous findings indicate that worsening of outcome after closed head trauma in rats may be caused more by edema formation than by hyperglycemia.     

A comparison of 0.5% bupivacaine, 0.5% ropivacaine, and 0.75% ropivacaine for interscalene brachial plexus block

The onset time and duration of action of ropivacaine during an interscalene block are not known. The potentially improved safety profile of ropivacaine may allow the use of higher concentrations to try and speed onset time. We compared bupivacaine and ropivacaine to determine the optimal long-acting local anesthetic and concentration for interscalene brachial plexus block. Seventy-five adult patients scheduled for outpatient shoulder surgery under interscalene block were entered into this double-blind, randomized study. Patients were assigned (n = 25 per group) to receive an interscalene block using 30 mL of 0.5% bupivacaine, 0.5% ropivacaine, or 0.75% ropivacaine. All solutions contained fresh epinephrine in a 1:400,000 concentration. At 1-min intervals after local anesthetic injection, patients were assessed to determine loss of shoulder abduction and loss of pinprick in the C5-6 dermatomes. Before discharge, patients were asked to document the time of first oral narcotic use, when incisional discomfort began, and when full sensation returned to the shoulder. The mean onset time of both motor and sensory blockade was <6 min in all groups. Duration of sensory blockade was similar in all groups as defined by the three recovery measures. We conclude that there is no clinically important difference in times to onset and recovery of interscalene block for bupivacaine 0.5%, ropivacaine 0.5%, and ropivacaine 0.75% when injected in equal volumes. IMPLICATIONS: In this study, we demonstrated a similar efficacy between equal concentrations of ropivacaine and bupivacaine. In addition, increasing the concentration of ropivacaine from 0.5% to 0.75% fails to improve the onset or duration of interscalene brachial plexus block.     

Schwingfestigkeitsverhalten von martensitaushärtendem Stahl mit rd. 18% Ni, 8% Co und 5% Mo

Ermittlung des Verhaltens unter Kurzzeitschwingbeanspruchung und im Dauerschwingversuch, der Kennwerte im Zugversuch, im Kerbschlagbiegeversuch sowie der Bruchzähigkeit (K_lc-Wert) an martensitaushärtendem Stahl mit rd. 18% Ni, 8% Co und 5% Mo nach Lösungsglühen und Warmauslagern. Einfluß der Korngröße und des mikroskopischen Reinheitsgrades sowie von Oberflächenbehandlungen durch Sandstrahlen oder Nitrieren. Beurteilung der ermittelten Eigenschaften des Stahles im Hinblick auf seine Verwendung.