Physical Properties of Crushed Air-cooled Blast Furnace Slag and Numerical Representation of Its Morphology Characteristics

Physical properties and geometrical morphologies of crushed air-cooled blast furnace slag （SCR） and crushed limestone （LCR） were comparatively investigated. The shape, angularity, surface texture and internal pore structure of aggregate particles for different size and gradation were numerically represented by sphericity （ψ） and shape index （SI）, angularity number （AN）, index of aggregate particle shape and texture （IAPST）, porosity and pore size, respectively. The results show that SCR is a porous and rough aggregate. Apparent density, void, water absorption and smashing index of SCR are obviously higher than those of LCR with the same gradation, respectively. However, bulk density of SCR is lower than that of LCR with the same gradation. SI, AN, IAPST and porosity of SCR are obviously higher than those of LCR with the same gradation, respectively. The smaller particle size of SCR, the larger of its AN, IAPST and porosity.

Characteristics of gaseous product from municipal solid waste gasification with hot blast furnace slag

Possibility of combustible gas production from municipal solid waste （MSW） using hot blast furnace （BF） slag has been studied.The objective of this work is to generate combustible gas from MSW using heated BF slag.In this experiment,the thermal stability of the MSW was analyzed by thermogravimetric analysis,and effects of temperature,gasifying agent （air,N2,steam） and BF slag on the gas products were investigated at 600？900 ？C.The thermogravimetric analysis indicates that the weight loss of MSW includes four stages：evaporation of the moisture,combustion of volatile materials,burning of carbon residue and burnout of ash.The contents of the combustible gas increase with increasing temperature,and the lower calorific value （LCV） increases rapidly at 600？900 ？C.It is found that volume fraction of CO,H2 and CH4 at different atmospheres increases in the order N2〈air〈steam.It is believed that BF slag acts as the catalyst and the heat carrier,which promotes the gasification reactivity of MSW.

Effect of Crushed Air-cooled Blast Furnace Slag on Mechanical Properties of Concrete

Morphology characteristics of mix aggregates with crushed air-cooled blast furnace slag（SCR） and crushed limestone（LCR） with 5-20 mm and 20-40 mm gradation were represented by numerical parameters including angularity number（AN） and index of aggregate particle shape and texture（IAPST）.The effect of mix aggregates containing SCR on compressive strength and splitting tensile strength of concrete was investigated.Fracture characteristics of concrete,interfacial structure between aggregates and matrix were analyzed.The experimental results show that porous and rough SCR increases contact area with matrix in concrete,concave holes and micro-pores on the surface of SCR are filled by mortar and hydrated cement paste,which may increase interlocking and mechanical bond between aggregate and matrix in concrete.SCR can be used to produce a high-strength concrete with better mechanical properties than corresponding concrete made with LCR.The increase of AN and IAPST of aggregate may enhance mechanical properties of concrete.

Status and development of mineral wool made from molten blast furnace slag

This study describes the characteristics of mineral wool and its applications,and also introduces the traditional process of mineral wool made from molten blast furnace （BF） slag. Compared with high energy consumption of the traditional process,the production of mineral wool by using molten BF slag will be able to take full advantage of the sensible heat of molten slag, and also reduce production costs. However, there are also further issues to resolve such as how to obtain the required amount of molten BF slag and how to make it homogeneous. Based on the physical and chemical properties of the molten BF slag,the investigation into the relationship between temperature and viscosity under different acidity coefficients of the slag and silicon mixture was conducted. Combined with the crystallization and phase diagram of slag wool, its heat resistance, water resistance, durability and corrosion resistance were analyzed. Finally, trends of the technology development are proposed.

Monitoring Method for Blast Furnace Wall With Copper Staves

A monitoring method that has been designed for the first time for blast furnace wall with copper staves manufactured in China was introduced. Combining the method of ＂inverse problem＂ and the concept ＂non-inverse problem＂, the monitoring program for blast furnace wall with copper staves has been realized, which can be used to calculate online the accretion thickness and temperature of hot surface of copper staves after obtaining the values of thermocouples of copper staves. The accretion state obtained in the actual investigation has proved that the result of the program is correct. The monitoring program shows that the accretion would easily fluctuate when the accretion layer is extremely thick or thin, thereby the stable and smooth operation of the blast furnace is hindered. By maintaining appropriate accretion thickness, both long campaigns and high productivity of the blast furnace can be achieved; furthermore, it can also optimize the operation of blast furnace and maximize its production. Approximately 30--50 mm in thickness of accretion layer is maintained on the wall of Shougang blast furnace 2, which can meet the requirement for obtaining both long campaign and high productivity.

Quantificational indexes for design and evaluation of copper staves for blast furnaces

The quantificational and normative design is the precondition of improving the design of copper staves for blast furnaces. Based on a 3-dimensional temperature field calculation model, from the view point of heat transfer and long campaigns note with the core of forming accretion, the forming-accretion-ability （FAA） and the rib hot surface maximum temperature difference （ATmax） as quantificational indexes to direct and evaluate the design of copper staves for blast furnaces were presented. The application of the two indexes in design essentially embodies the new long campaigns in the stage of design. With the application of the two indexes, good results can be obtained. Firstly, it was suggested that the rib height of a copper stave can be reduced to 15 mm, which is a new method and theory for the reduction of copper staves. Secondly, the influence of insert on FAA and ATmax, is decided by the volume of insert. According to this, the principle of design for the hot surface geometry of copper staves was put forward that the ratio of the rib hot surface to the copper stave hot surface （abbreviated as the ratio of rib to stave） must be maintained in the range of 45% to 55%; for the present copper stave with a 35-40 mm thick rib, the ratio of rib to stave in the range of 50% to 55% can optimize the design of copper staves; for the copper stave with a smaller rib thickness, for example 15 ram, the ratio of rib to stave in the range of 45% to 50% can optimize the design of copper staves. It can be summarized that the thicker the rib thickness, the larger is the ratio of rib to stave. 2008 University of Science and Technology Beijing. All rights reserved.

Softening–melting–dripping characteristics and evolution mechanism of vanadium-bearing titanomagnetite carbon composite briquette used as novel blast furnace burden

Vanadium-bearing titanomagnetite carbon composite briquette(VTM-CCB)was proposed as an innovative and promising blast furnace burden to realize low-carbon and high-efficiency ironmaking.To optimize the compositions of VTM-CCB based on its softening–melting–dripping characteristics,the evolution behavior and mechanisms of VTM-CCB in cohesive zone and dripping zone were investigated by conducting softening–melting tests under blast furnace conditions.The results show that the structure evolution of VTM-CCB in softening–melting process is correlated to the molten slag,metallic iron,liquid iron,and residual carbon.With the molar ratio of the fixed carbon to the reducible oxygen in iron oxides(FC/O ratio)ranging from 0.8 to 1.0,the VTM-CCB tends to form dense structure and accelerate the softening and melting.With increasing the FC/O ratio to 1.2 and 1.4,the VTM-CCB tends to form concentric circular structure,which could suppress the collapse of packed bed,shift down the location of core cohesive zone,and improve the gas permeability.Although the appropriate increase in FC/O ratio could improve the softening–melting performance of VTM-CCB,a higher FC/O ratio could also promote the precipitation of Ti(C,N),thereby thickening the molten mixtures and deteriorating the dripping behavior.Fully considering the softening–melting–dripping characteristics and permeability,the appropriate FC/O ratio of VTM-CCB should be controlled in the range of 1.0–1.2.

Numerical Simulation of Heat Transfer of High-Temperature Slag Flow Inside the Blast Furnace Slag Trench

To investigate the flow and heat transfer process of blast furnace slag through the slag trench after the slag is discharged,a three-dimensional physical model is established and simulated according to the actual size of the slag trench and the physical properties of the high-temperature slag.The temperature field and flow field distribution of the high-temperature slag liquid inside the slag trench is obtained by numerical simulation under different working conditions,and the effects of operating conditions such as slag trench inclination,high-temperature slag inlet flow rate,and inlet temperature are investigated.The results show that the flow rate of high-temperature slag is related to the slope of the slag trench,the greater the slope of the slag trench,the higher the flow rate of high-temperature slag,in which the highest average speed can reach 2.23 m/s when the slope is 8%;changing the inlet flow rate,flowing through the slag trench,the high-temperature slag reaches the highest flow rate at the same position,the overall flow rate changes tend to rise first and then decrease,and the greater the inlet flow rate,the higher the temperature change of high-temperature slag.The higher the inlet flow rate,the higher the temperature change of high-temperature slag,the higher the temperature of high-temperature slag out of the slag trench;the higher the inlet temperature,the higher the overall flow rate of high-temperature slag,and the position of the highest flow rate is relatively backward.

Model of Forming-Accretion on Blast Furnace Copper Stave and Industrial Application

Copper staves have been equipped on nearly all of BF （blast furnaces） with volume over than 1000 m3 in China since their introduction from abroad about more than 10 years ago. Because of short application and lack of experience, phenomena of thickened or naked of copper stave happen occasionally which influence production severely. So it is important to study the model of forming-accretion on BF copper stave and realize real-time monitoring of forming-accretion on different copper staves. Therefore, mathematic model of calculating accretion thickness by heat flow of BF is proposed, and the calculated results indicate that accretion thickness could be kept at a reasonable range of around 50 mm by controlling heat flux around 22.0 kW/mz. The monitoring program based on the model was applied to a certain BF in China successfully, and it is found that slip of BF near the inner wall is one of most important reasons that cause fluctuation of accretion thickness. During the period of scheduled maintenance of the certain BF, the thickness of accretion measured through the static pressure holes is in good accordance with the value calculated by the monitoring program, so the results calculated by the monitoring program can be used to guide industrial production

Influence of particle size on combustion behavior of bamboo char used for blast furnace injection

The combustion behavior of bamboo char and its relationship with particle sizes were evaluated using thermo-gravimetric analysis.The results showed that the combustion properties of bamboo char were much better than those of the anthracite used as a coal injected for blast furnace ironmaking due to its porous structure,disordered microcrystalline and higher catalytic index of ash minerals.When the particle size increased from -0.074 to 0.500-1.000 mm,the ignition temperature and burnout temperature of bamboo char increased,while the combustible index and comprehensive combustion characteristic index decreased slightly.The apparent activation energies of non-isothermal combustion of bamboo char and anthracite were calculated based on the distributed activation energy model.The results showed that the average activation energy was 162.86 kJ/mol for-0.074 mm anthracite,while it ranged from 71.01 to 89.44 kJ/mol for bamboo chars of different sizes.It revealed that the combustion reactivity of bamboo char in the largest size (0.500-1.000 mm)was much better than that of -0.074 mm,anthracite;thus,the size of biomass char could be enlarged to the maximum size specified by the injection application of blast furnace.

CO_2 Gasification Characteristics of High and Low Reactivity Cokes

In order to effectively utilize the high reactivity coke, the gasification characteristics of high and low reactivity cokes were investigated at 1100 ℃. Low reactivity coke A and high reactivity coke B were chosen and charged into the reaction tube in two methods. The results indicated that the mass loss ratio of high reactivity coke in mixed cokes was more significant than that of single high reactivity coke in the middle stage of reaction. Nevertheless, the mass loss ratio of low reactivity coke in mixed cokes was less than that of single low reactivity coke. It was mainly attributed to gas diffusion and internal reaction of coke. When high and low reactivity cokes were mixed, the practical average mass loss ratio was nearly the same as the weighted average. The microscopic structures of coke indicated that with the increase of reaction time, the external and internal layers of low reactivity coke reacted more uniformly with CO2, whereas the reaction degree of external layer of high reactivity coke was obviously higher.

石灰-高炉矿渣改良膨胀土强度特性试验研究

因膨胀土具有吸水膨胀、失水收缩等不稳定性特征,使用高炉矿渣作为新型固化剂,并与无机材料石灰组合对膨胀土进行改良。对改良膨胀土开展自由膨胀率、液塑限、无侧限抗压强度和抗剪强度等指标的研究,探讨并分析了石灰-高炉矿渣(L-BLS)改良膨胀土在不同养护龄期以及不同改良剂掺量下的无侧限抗压强度变化规律。结果表明:使用L-BLS改良膨胀土能够显著提高膨胀土的早期强度;改良膨胀土的强度随养护龄期及改良剂掺量的增加而增强;当掺入6%石灰及9%高炉矿渣时,对应龄期的无侧限抗压强度最大,材料的有效利用率最佳。

新钢10号高炉降料面处理炉墙结厚实践

新钢10号高炉因烧结矿质量波动较大、炉况稳定性差及管道频繁发生等原因,出现炉墙结厚。首次采用降料面的方法处理炉墙结厚,降料面过程中炉况稳定,恢复上料后24h内炉况恢复正常。认为在降料面的过程中应密切关注煤气中H_(2)、O_(2)含量的变化,确保含H,量≤12%;随着料面的下降,炉墙结厚物逐步显露之后,结厚物下部受到高温煤气流冲刷作用,上部受到炉顶雾化水冷却作用,结厚物产生裂缝塌的过程中,温度的变化是关键。10号高炉炉墙结厚处理后,主要技术经济指标明显改善,日产量上升155Vd,煤气利用率上升1.1个百分点,燃料比下降10kg/t。

梅钢5号高炉炉墙结厚的原因及炉况恢复

对梅钢5号高炉炉墙结厚的原因及炉况恢复进行了总结。5号高炉开炉以来首次炉墙结厚,主要征兆是全炉水温差下降和炉身静压力曲线值出现偏差。结厚的主要原因:一是焦炭质量劣化,入炉焦炭CRI最高上升至23.6%左右,灰分在12.5%左右;二是烧结矿质量劣化,品位降至57.0%左右,FeO含量降至8.5%左右;三是炉渣(Al_(2)0_(3))最高上升至19.0%左右;四是入炉有害元素含量超标,锌负荷升至0.36 kg/t,碱金属负荷最高上升至3.0 kg/t;五是炉况持续恶化。通过采取发展边沿气流、提高入炉风量、提高炉温加锰矿洗炉等措施,炉况得到恢复。

唐钢新区高比例球团矿冶炼高炉的操作炉型控制

唐钢新区高炉设计秉承“现代化、绿色化”理念,采用50%球团矿冶炼,为适应高比例球团矿冶炼,优化炉型设计,冷却设备采用全铸铁冷却壁形式。高比例球团矿冶炼下,因高炉边沿不稳、炉墙易结厚,操作炉型不易控制。通过采取加强原燃料质量控制、合理匹配上下部操作制度、合理控制水温差、快速处理炉墙结厚等措施,高炉保持了较长周期稳定顺行,各项技术指标持续提升。2022年下半年以来,高炉利用系数保持在2.74~2.97(m^(3)·d),从使用效果看,全铸铁冷却壁能够适应高比例球团矿冶炼条件下的高强度冶炼要求。

湘钢2号高炉炉身上部结瘤的原因及处理

对湘钢2号高炉炉身上部结瘤的原因及处理进行了阐述。2号高炉从炉墙轻微结厚,逐步发展成为较为严重的结瘤,瘤体厚度达800mm以上,分析结瘤的原因,主要是块矿入炉粉末多及烧结矿质量劣化,炉内碱金属循环富集现象严重,炉身中上部冷却强度过大。根据2号高炉自身实际状况,采用物理击打法消除结瘤,实现了炉况的快速恢复,生产指标明显改善。这次结瘤处理过程教训深刻,认为高炉操作炉型的维护应以预防为主,无论是结厚还是结瘤,预防是关键,处理要及早,不能犹豫不决。

昆钢2号高炉炉况失常的原因及处理措施

对昆钢2号高炉2023年4月8日发生的炉况失常的原因及处理措施进行分析总结。认为这次炉况失常的直接原因是风口小套长时间漏水和炉墙黏结,间接原因是高炉计划检修周期过长、烧结矿冶金性能劣化、熔剂质量波动造成渣相波动和炉顶洒水效果不好。从装料制度、送风制度、造渣制度、热制度等方面进行系统调整,主要通过采取缩矿批退负荷、集中加焦、调整布料矩阵、增加水量提高冷却强度等措施,炉况实现快速恢复。4月12日,2号高炉焦炭负荷提升至4.54,日产量恢复到7058.789t/d,燃料比稳定在516kg/t。

首钢股份2号高炉炉墙结厚的成因及处理

首钢股份2号高炉因原燃料质量变差、抗原料质量波动能力差、操作应对不及时等原因导致炉墙结厚,炉况波动时间较长。通过采取减轻焦炭负荷、调整装料制度、降低炉渣碱度、使用萤石洗炉、更换风口等措施进行处理,炉况恢复正常。认为:①当进厂焦炭质量不达标时,应及时向上反馈,以免造成生产困难;②在原燃料质量稳定性较差的条件下,应保持煤气流通路,重视中心气流的作用,提高抗外围原燃料质量波动的能力;③针对原燃料条件及其质量波动,应及时修改、制订调整措施,保证高炉顺行。

涟钢6号高炉炉身结厚的处理及强化冶炼措施

对涟钢6号高炉炉身结厚的表现及形成进行了简述,重点对结厚的处理及强化冶炼措施进行了阐述。通过采取缩矿批降负荷、控风氧控压差、调矩阵疏中心及抓炉前出铁等措施,炉身结厚渣皮脱落,炉况得以恢复;通过采取合理优化焦炭装人结构、活跃炉缸、优化布料制度及优化布料制度等措施,高炉煤气利用率提高至45%~46%,日产量提升至7100d以上,主要技术经济指标得到优化,实现强化冶炼。认为控制炉腰和炉身中下部温度适宜、稳定,是预防结厚的有效措施;炉芯温度最早反映炉缸工作状态,当出现下降趋势时,应及时采取措施。