Cold Simulation of Metalloids Transport in Blast Furnaces

Metalloids normally get transferred at the interface of metal droplets passing through the slag system in the dropping zone and at the slag‐metal interface in the hearth zone in the lower region of a blast furnace. In these high temperature processes, the mass transport being the rate‐controlling factor, the viscosity of the slag system determines the kinetics of the refining reactions accompanied by mass and heat transfer at the metal droplets and slag interface. Slag systems generally possess random network structures comprising internal regions of weak ordering. The presence of these regions may result in non‐Newtonian behaviour of the slag. The rheological characteristics of a fluid relating to its network structure is expressed in terms of the indices consistency (k') and flow behaviour (n'). The extent of metalloids presence in hot metal is subjected to their residence time at the slag‐metal interface. The metal droplet descent through a surrounding fluid system has been studied and a co‐relation between drag Reynolds number and modified Reynolds number has been obtained. This correlation has been used to determine the drag velocity of a metal droplet falling through a slag system and the residence time distribution (RTD) of the metalloids at the slag‐metal interface in the lower region of the blast furnace.     

攀钢高炉锌平衡测定

对攀钢1、2号高炉的原燃料、生铁、炉渣、瓦斯泥、净煤气灰尘和出铁场烟尘进行了取样，根据试样化验的锌含量，结合高炉生产数据对攀钢1、2号高炉进行了锌平衡计算，分析了锌在高炉各收入项和支出项中的分布。结果表明：攀钢高炉的锌负荷很高，对高炉的正常生产造成严重危胁；入炉原料是攀钢高炉锌的主要来源，是造成攀钢高炉锌负荷高的主要原因：支出的锌主要通过炉顶随高炉煤气排出，绝大部分进入瓦斯泥。     

Effect of Direct Reduced Iron on Oxygen Distribution between Slag and Bath in Electric Arc Furnaces

Test charges containing 40 to 95% direct reduced iron (DRI) were melted in two identical electric arc furnaces. Slag and the corresponding metal samples were collected from the furnace in the course of the steelmaking process and from the ladle after deoxidation and composition adjustment. The temperature was measured just before sampling. The activity coefficient and activity of total ferrous oxide in the slag were determined by using the theory of regular ionic solutions. The activity was used to assess the oxygen concentration in the metal. The effect of slag composition on Fe_tO activity coefficient and activity was investigated. The enthalpy of solution of total ferrous oxide in the slag was found to be 78 kJmol^?1. The ratio of activity to concentration of Fe_tO is equal to 0.0138. The effects of DRI proportion and degree of metallization on α^Fe,O were investigated. The activity coefficients of oxygen and carbon in the bath are 0.7243 and 1.0825, respectively. The activity coefficient and activity of oxygen in the metal decrease with increasing carbon concentration, carbon activity coefficient and activity. An “oxide capacity” has been developed which does not need the use of α^Fe,O. It correlates strongly with temperature over the range from 1500 to 1670°C. The basicity has only a small influence compared with the large temperature effect. The oxide capacity increases with growing DRI proportion and decreases with increasing metallization between 93.43 and 95.25%. Oxygen distribution between slag and metal was assessed by using the oxide capacity. Calculated values compare well with the corresponding data obtained from slag and metal analyses. The oxide capacity can be used in monitoring the steelmaking operation.     

Removal of Phosphorous from Steel Produced by Melting Sponge Iron in Induction Furnace

In secondary route of steelmaking, production through induction melting furnace contributes about 31 % of India’s total steel production. The main raw materials used are steel scrap, cast iron and sponge iron. In India, majority of the induction furnaces are operated using acidic lining of silica based ramming mass to produce structural steel where basicity cannot be maintained to remove phosphorous and sulphur. In the present work, efforts are being made to generate the experimental data for refining of steel in 750 kg induction furnace. The basicity is maintained by addition of CaO and MgO in the form of flux. The slag is made oxidizing in nature by addition of sponge iron in the bath. Oxidation potential of the slag is fulfilled by presence of FeO in sponge iron. In every single heat, samples of slag and metal are collected. The degree of dephosphorization obtained is as high as 82 %.     

Manganese extraction from slag obtained in the production of refined manganese ferroalloys

The extraction of manganese from the tailings slag obtained in the production of refined manganese ferroalloys is studied thermodynamically and experimentally. In such extraction, the slag reacts with metal melts (hot metal, ferromanganese, and ferrosilicomanganese) containing reducing elements (carbon and silicon), with the goal of increasing the overall transfer of manganese to the final manganese ferroalloys. According to the results, the reduction of manganese by carbon only occurs in the case of hot metal. A method is developed for alloying hot metal with manganese from tailings slag obtained in the production of refined manganese ferroalloys.     

Electroslag Treatment of Liquid Cast Iron

The processes that occur in the liquid metal–slag system during electroslag treatment of cast iron are studied from an electrochemical standpoint. The role of electrolysis in the electroslag process is shown, and a method for producing high-strength cast iron with globular graphite using electrolysis of a slag containing magnesium oxides and fluorides is proposed and tested.     

Application of the triad of blast furnace,oxygen converter,and electric arc furnace for reducing of carbon footprint

Carbon footprint is the mass of carbon formed in the full cycle of manufacturing one kind or another product. This carbon is included in greenhouse gases. During production of iron and steel are generated carbon monoxide and greenhouse gases: methane, and carbon dioxide. Methane and carbon monoxide burn to carbon dioxide by secondary energy resources. By this means, the carbon footprint by the production of iron and steel has determined by the weight of carbon dioxide formed in this production. As results of analysis of the processes of manufacture of iron and steel, it has revealed that the tandem of blast furnace with electric arc furnace is characterized by a lower value of integrated emissions of CO₂ than the tandem of blast furnace with an oxygen converter. It was proposed to process of the cast iron made by one blast furnace, then in the oxygen converter, and, at last, in one or more electric arc furnaces. Moreover, the electric arc furnace is loaded by 30% of iron produced in blast furnace, and the remaining 70% are complemented by metal scrap. In the oxygen converter is loaded, the part of cast iron (75–85%), that remained after processing in the arc furnace. The converter is applied the metal scrap for full loading. Calculations of total emission of carbon dioxide for different triads of these units are made. Simultaneous use of oxygen converter with electric arc furnaces for cast iron smelting (obtained from one blast furnace) helps to reduce reliably the emission of carbon dioxide to 20% as it is follows from these calculations. This suggests that such a triad of used units conforms to green technology. Example of the use of mentioned triad is for a full load of the converter applied to metal scrap. The calculations total emissions of carbon dioxide for different triads of these units were performed. From these calculations it follows that the simultaneous use of oxygen converters after electric arc furnaces for smelting iron (obtained from one blast furnace), it helps to reduce the emission of carbon dioxide to 20%. This suggests that this triad of used units conforms to green technology. An example of using this triad is in the Magnitogorsk Iron and Steel Works, where along with the oxygen converter, electric arc furnaces with the use of locally produced electricity at burning fuel of secondary energy resources from units, in which the fuel is burnt. This practice can be recommended for a number of other metallurgical enterprises.     

Reconstruction of the cast house of a blast furnace

The use of an integrated engineering system in the reconstruction of cast houses makes it possible to make more efficient use of blast furnaces based on several characteristics: it improves the working conditions for furnace personnel (hearth attendants) involved in tapping the smelting products; it reduces the amount of heat lost from the pig iron by maintaining its initial temperature; it reduces the amount of pig iron lost with the slag; it significantly decreases the volume of pollutants generated; it reduces penalties for polluting the environment. __________ Translated from Metallurg, No. 7, pp. 32–33, July, 2006.     

黄铜炉组除尘系统改造实践

在全面分析黄铜炉组烟气污染原因的基础上,对其收尘排烟系统进行了有针对性的改造,通过增强炉膛负压、控制烟气走向、转铜水时的强制排烟、合理分配风机风量等,大大提高了烟尘回收率.     

Reaction equilibria in the production of manganese ferroalloys

A laboratory investigation has been carried out to determine slag/metal and slag/metal/gas equilibria relevant to production of manganese ferroalloys. The metal phase was normally composed of MnSi-C_sat alloys, but in some experiments, the alloys contained up to 15 wt pct Fe. Different slag systems were used: MnO-SiO₂, MnO-SiO₂-CaO, MnO-SiO₂-Al₂O₃, and quaternary MnO-SiO₂-CaO-Al₂O₃ with fixed CaO/Al₂O₃ weight ratios of 1.5 and 3. The experiments were normally made in CO gas atmosphere at temperatures ranging from 1450 °C to 1600 °C. The results give comprehensive information about equilibrium relations.Partial andcomplete equilibria are illustrated in equilibrium diagrams. Partial equilibrium is a situation in which equilibrium is established with respect to certain variables but not to others, in this case, between slag and metal but not with the gas phase. The effect of temperature was found to be of minor importance for the partial slag/metal equilibrium, whereas the complete slag/metal/gas equilibrium is considerably influenced by both temperature and CO pressure. As expected, increasing temperature and decreasing CO pressure will reduce the equilibrium MnO content of slags. The influence of alumina addition to the slag phase and of iron to the metal phase is also discussed.     

涟钢高炉有害元素的分布与控制

研究分析了K,Na,Pb,Zn,Cu,As,Sn等有害元素在涟钢高炉炉料及产品中的分布情况。以光学显微镜、荧光分析仪、扫描电镜等仪器研究了有害元素在烧结矿、球团矿、块矿、焦炭、生铁、炉渣中的分布形态及其在富集载体渣皮、耐火材料、死铁层中的分布情况。同时,对高炉主要原燃料及产品中有害元素与其他元素的相关性进行了分析,并提出了一些控制高炉有害元素危害的方法与原则。     

Improved manganese extraction in the production of manganese ferroalloys

In the production of manganese ferroalloys from ore, about 50% of the manganese in the ore is lost. The manganese lost with the enrichment-slag tailings may be returned to the production of manganese ferroalloys by dithionate method of enrichment of the slurries. A technology is developed for the production of high-carbon ferromanganese from concentrate obtained by the chemical enrichment of tailings slurries. Low-phosphorus Mn slag is used in the production of ferrosilicomanganese and refined manganese ferroalloys. A method is described for alloying hot metal with manganese from slag during the production of lowand medium-carbon ferromanganese. Processes are developed for the production of medium-carbon ferromanganese by mixing ore–limestone melt with high-carbon ferromanganese and removing the phosphorus from Mn-bearing melts by bubbling with CO. The degree of phosphorus removal (70–90%) depends on the bubbling time. By means of improved production of manganese ferroalloys and extraction of manganese from slag and slurries, the manganese extraction may be significantly increased.     

Silicon distribution between blast furnace slag and hot metal

Abstract

Analyses of slag and hot metal in daily average samples from a 1033 m³ blast furnace charged with 100% self-fluxing sinter, and published data from two 2000 m³ furnaces with different proportions of various pellet types in the charge, have been used to calculate the ‘silicate capacity’ of slag and to investigate the effects of basicity and temperature on silicate capacity and silicon distribution ratio. Regression equations have been developed which show that both silicate capacity and silicon distribution ratio increase with increasing basicity and decreasing temperature. The temperature effect is very large compared with the influence of slag basicity. Similar relationships between silicate capacity and temperature are obtained individually for both furnace types as well as by combining their data together and with the data from other furnaces. Silicon distribution ratios calculated by using the silicate capacity of the slag compare well with the results found from slag and metal analyses.     

陕西韩城芝川古代冶铁遗址初步考察

韩城芝川古代冶铁遗址位于陕西省渭南市韩城芝川镇芝西村,遗存面积超4 000 m²,考古年代为西汉。科研团队对该遗址开展冶金考古田野调查并采集到炉渣、陶片等遗物,使用扫描电镜及能谱(SEM-EDS)、金(矿)相显微观察等手段对采集到的18个冶炼遗物进行成分分析和显微结构观察。结果表明,16个炉渣为硅钙铝系高钙低铁炉渣,基体主要为玻璃相、偶见铁橄榄石,其产品是生铁,应为生铁冶炼炉渣。1个炉渣为高铁渣,以浮氏体为主、间有铁橄榄石和极少量玻璃相;1个样品的块状金属为熟铁,很可能为生铁炒钢的遗物。该遗址主要是生铁冶炼遗址,同时进行炒钢冶金活动,是迄今发现陕西渭南地区最早的生铁炒钢遗址。     

极点配置PID自校正调节器及其在罩式退火炉群控系统中的应用

本文根据闭环极点配置的思想,推导了一种具有PID结构的简单自校正控制算法,该算法具有结构简单、鲁棒性强、容易实现,适用于非最小相位系统等优点。该算法已经应用于罩式退火炉微机群控系统中,实时控制结果表明:该算法具有很好的跟踪特性和调节特性,炉温控制效果比常规的仪表PID调节有较大的改善。该算法适用于一般慢时变工业过程。     

包钢炼钢厂转炉工艺优化

炼钢和连铸生产过程中产生了大量的含铁尘泥、连铸切割渣、渣钢等含铁物质,为了减少这些含铁物质的外排和污染,在转炉中加入这些含铁物质,但是转炉工艺操作出现了波动,部分炉次钢铁料消耗较高。通过采用"留渣+双渣"工艺,在留渣的基础上将转炉吹炼分为两个阶段;同时在吹炼过程中对底吹进行控制,显著地降低喷溅发生。现有操作工艺进行优化后,钢铁料、渣料消耗大幅减少,显著地降低了转炉炼钢的生产成本。     

山西翼城冶南汉代冶铁遗址初步调查

冶南遗址位于山西省临汾市翼城县冶南村,面积约1.2 km²,考古年代为西汉。采用X射线荧光分析仪(EDX)、扫描电镜及能谱分析仪(SEM-EDS)、金(矿)相显微镜等对冶南遗址采集的6个炉渣和2个金属铁块进行了基体成分和显微组织检测分析。结果表明,6个炉渣样品为硅钙铝系低铁渣;2个铁块样品为熟铁,可能是生铁炒钢产品。判断该遗址为生铁冶炼遗址,同时也是生铁炒钢遗址。该遗址是目前山西地区确认的第一处大型生铁冶炼及炒钢的汉代官铁遗址。     

Optimization of complex injection in converters at OAO NLMK

The use of complex injection in converters permits intensification of oxygen injection and steel output and also reduction in the injection time, the oxidation of the intermediate product, the carbon content in the metal after injection, and the total iron content in the slag. In addition, the consumption of reducing agents and ferroalloys is reduced for all steel and the range of steel with carbon and phosphorus content is expanded.     

Modern steelmaking technologies

Based on our experimental results, we propose the following low-cost technologies in the field of steelmaking for implementation: the use of briquettes, which are alternative to solid cast iron and scrap metal and contain scale and carbon-containing wastes, in the charges of electric furnaces and converters; microalloying of metal by nitride phases; modification of steel in a ladle by SiCa + Ba master alloys; and the application of daisy-chain blowing of the metal in a ladle (small-bubble conditions). The efficiency of these technologies for melting in electric furnaces and secondary metallurgy is supported. It is shown that electromagnetic mixing of metal in combination with the optimum conditions of soft reduction of a slab should be used in continuous casting to form an internal structure in a slab at the level of the first class on the Mannesmann scale.     

Kinetics of reduction of lead oxide in liquid slag by carbon in iron

The reduction of lead oxide in dilute solution in CaO-Al₂O₂-SiO₃ slag by carbon dissolved in iron was investigated using a composite crucible as a container so as to exclude graphite from the system. The variables studied to elucidate the reaction mechanism were pressure inside the crucible, carbon content of the metal, lead oxide concentration in slag, and slag composition. The experimental results are best explained by postulating the existence of a gas film at the slag metal interface. It is suggested that the rate controlling step for the lead oxide reduction by carbon is a chemical reaction at the gas/slag interface. The rate constant for up to 3 wt pct PbO in the slag and 2.0 to 4.3 pct C in iron at 1400 °C as calculated from the present study is 4.6 x 10^-4 mol/cm²/min/atm.