Thermodynamics calculation on the oxidation and sulfur removal abilities of slag in EAF dust pellet reduction process

ＥＡＦｄｕｓｔｈａｓｂｅｅｎｃｌａｓｓｉｆｉｅｄａｓｈａｚａｒｄｏｕｓｗａｓｔｅ ,ａｎｄｉｔｉｓｈａｒｍｆｕｌｉｎｔｈｅｃｏｎｖｅｎｔｉｏｎａｌｌａｎｄ ｆａｌｌｄｕｅｔｏｃｏｎｔａｉｎｉｎｇｈｅａｖｙｍｅｔａｌｓ[1] .Ｍｏｓｔｒｅｃｙ ｃｌｉｎｇｍｅｔｈｏｄｓ[2 8] ｄｅｖｅｌｏｐｅｄｆｏｒｔｈｅｄｕｓｔｓａｒｅｏｎｌｙｆｏｒｔｈｅｒｅｃｏｖｅｒｙｏｆｌｅａｄ ,ｚｉｎｃａｎｄｃａｄｍｉｕｍ .ＴｈｅＥＡＦｄｕｓｔｆｒｏｍｓｔａｉｎｌｅｓｓｓｔｅｅｌｍａｋｉｎｇｍａｉｎｌｙｃｏｎ ｔａｉｎｓｎｉｃｋｅ…     

多功能调渣剂在电炉冶炼中的试验研究

对ZY型电炉多功能进行了调渣剂工业性试验。实践表明炉渣泡沫化效果显著,冶炼电耗相对降低4（kW·h）/t;炉渣TFe下降幅度较大,相对降低率达10%￣20%。从理论上探讨上述效果的机理。认为随着电炉生产效率和比功率的不断提高,在电炉冶炼过程中采用一种既能使炉渣泡沫化,又能降低炉渣TFe的电炉多功能调渣剂十分必要。     

不锈钢电弧炉粉尘的物理化学特性及形成机理探讨

本研究采用多种实验检测方法分析了不锈钢电弧炉粉尘的物理特征和化学特性。扫描电镜分析结果显示粉尘的形貌特征为聚合颗粒；X射线荧光仪（XRF）和ICP分析结果说明粉尘的化学成分随电弧炉冶炼炉料的不同而改变；X射线衍射（XRD）及波形分析确定了粉尘的物相组成，尤其明确了铬在粉尘中以CrO和FeCr2O4的形式而不是以Cr2O3的形式存在；电子探针（EPMA）分析了粉尘内主要元素的分布，有利于粉尘在冶炼过程的形成机理的探索。研究结果可为不锈钢电弧炉粉的控制、处理及综合利用提供数据。     

不锈钢电弧炉粉尘加热过程的TGA及FTIR分析

本研究采用热重分析仪(TGA)和傅里叶变换远红外气体分析仪(FTIR)检测了不锈钢电弧炉粉尘的加热过程,确定了加热过程中粉尘热性质变化的3个阶段.第1阶段表现为失重,它是由水分的蒸发以及粉尘中的游离碳与金属氧化物作用所致.第2阶段表现为增重,粉尘中的金属与空气中的氧发生氧化反应.第3阶段为缓慢失重过程,粉尘中部分金属挥发进入气相.研究结果可为不锈钢电弧炉粉尘的直接回收及固化处理提供数据.     

多功能调渣剂在电炉冶炼中的试验研究

研究了ZY型电炉多功能调渣剂工业性试验实践。表明炉渣泡沫化效果显著,冶炼电耗相对降低4（kW.h）/t;炉渣TFe下降幅度较大,相对降低率达10%-20%。从理论上探讨上述效果的机理。认为随着电炉生产效率和比功率的不断提高,在电炉冶炼过程中采用一种既能使炉渣泡沫化,又能降低炉渣TFe的电炉多功能调渣剂十分必要。     

电炉炼钢厂粉尘在微波场中的升温特性

对电炉炼钢厂粉尘在微波场中的升温特性进行研究。结果表明,电炉炼钢厂粉尘对微波具有很好的吸波能力,其中不锈钢厂电弧炉粉尘在微波场中约15 min内温度就可达1000℃以上。随着微波功率的增加,粉尘表观升温速率增大。不同配碳比下粉尘的表观升温速率均较大,介于105-126℃/min之间。随着物料质量的减少,在微波场中粉尘的表观升温速率增大。粉尘颗粒粒径对表观升温速率的影响不显著。     

不锈钢冶炼电炉渣结构性质及浸出行为研究

研究电弧炉（EAF）渣的结构性质及渣中重金属离子的浸出行为。结果表明,EAF渣呈碱性,渣中Fe、Cr和Ni等金属元素主要以金属颗粒、（Cr,Al）2O3和（Fe,Mn,Mg）（Cr,Al）2O4晶体形式存在,具有较高的回收价值;电炉渣中可浸出重金属离子含量未超出国家标准,但存在Cr（III）再氧化为Cr（VI）的可能;Cr（VI）浸出量随浸出时间延长而增加,且Cr（VI）在蒸馏水中的浸出能力较冰醋酸中强。因此,EAF渣应尽量避免堆放或填埋在低pH场所,以防止其中重金属离子浸出。     

EAF steelmaking process with increasing hot metal charging ratio and improving slagging regime

A new electric arc furnace (EAF) steelmaking process with increasing hot metal charging ratio and improving slagging regime simultaneously was developed and applied in a 50 t electric arc furnace for more than a year at No.1 Steelmaking Plant of Shanxi Taigang Stainless Corporation Limited. The essential fact of the new EAF steelmaking process was to charge hot metal in two portions or steps: firstly, 35wt%-40wt% hot metal was pretreated by blowing oxygen in a specially designed reactor for decar-burization...     

Study on stainless steelmaking dust agglomeration

A new direct recycling technology was developed to recover the valuable metals present in the stainless steelmaking dust and protect the environment. The agglomeration behavior of the dust was analyzed to ensure the requirements of the direct recycling. The main characteristics such as strength, leachability, structure and chemical composition of the pellets were investigated. SEM images show a significant amount of porosities affecting the strength of the pellets and the arrangement of particles in the pellets reveals that no recrystallization bonds are formed, resulting in the poor strength of the pellets. When lignosulfonate is applied as the binder for the agglomeration and the green pellets are dried at room temperature for 60 h, the strong pellets can be obtained without milling the dust. The result of leachability tests shows that the pellets agglomerated can not satisfy the regulations set by the environmental protection agency of US. And it will cause some environmental problems in the long storage of pellets.     

钛铁矿熔炼过程中DC炉内挂渣层厚度控制的研究

分析了炉内的工艺温度和渣中MgO的含量随加热时间的变化特征．结果表明DC炉内挂渣层厚度主要与炉内的工艺温度和渣中MgO的含量有关．整个实验过程的工艺温度控制在1700～1750℃范围内,渣中MgO质量含量控制到小于1．8％时,可有效避免炉壁烧穿．随工艺温度的增加,渣中MgO质量含量增加,挂渣层减薄．研究熔炼过程中DC炉内挂渣层厚度变化对熔炼工艺的稳定控制和生产效率的提高具有重要的意义．     

低成本高炉炼铁科学化管理与操作

低成本高炉炼铁是钢铁厂在激烈的市场竞争中取得最大经济效益的必要条件.本文主要从低燃料比指标控制、合理炉料结构、混合煤粉喷吹、高炉灰回收利用等4个方面进行＂低成本高炉炼铁＂科学化管理与操作的探索,通过挖掘高炉炼铁工序在节能降耗的潜能,最大限度降低高炉炼铁生产的成本.     

基于阻抗模型电弧炉供电系统分析与仿真

根据实际交流电弧炉负荷条件和冶炼期间电弧的电气特性,建立了改进的三相非线性时变阻抗模型。该模型考虑了电弧炉控制参数、线路特征及冶炼不同阶段对电弧阻抗的影响。用Matlab实现了电弧炉模型的仿真,结果表明,提出的模型适合于研究电弧炉供电系统的电压波动。     

马钢电弧炉弹簧钢60 Si2 MnA氧含量技术可行性研究

针对马钢100t电弧炉EAF→LF→RH生产弹簧钢60Si2Mn A的冶炼生产工艺流程,采取系统的取样、综合分析弹簧钢冶炼过程中全氧变化规律及影响因素,结果表明:在电弧炉-LF精炼-RH真空处理中,全氧含量基本是逐渐降低的;通过精炼全程底吹氩气,采用顶渣操作和高碱度(R=3.5)精炼渣,来降低渣中氧化物的含量及活度,均有利于降低弹簧钢中的全氧含量;钢水中氧含量最终可以控制在10ppm以内;     

微波碳热还原不锈钢厂电弧炉粉尘的热力学及实验研究

采用微波加热方法进行碳热还原不锈钢厂电弧炉粉尘,并计算粉尘中金属氧化物的理论开始还原温度。结果表明,微波碳热还原不锈钢厂电弧炉粉尘在热力学上可行。实际测量的粉尘中金属开始还原温度比理论计算值低。微波加热物料过程中形成的热点和电弧可能导致局部高温,有利于碳热还原反应的进行。在900℃下,有部分粉尘被还原,随着温度的升高,粉尘的还原程度增大。还原出来的金属相主要以Fe-Cr-Ni合金的形式存在,且成分分布不均匀,残余相主要以FeCr2O4、Fe3O4、CaSiO3、（Mg,Al）SiO3和CaMgSiO4形式存在。     

Isothermal kinetics of the first stage reduction of magnetite cold bond pellets with carbon monoxide

The reduction of Fe₃O₄ to Fe is accomplished in two stages. In order to understand the reduction mechanism of magnetite cold bond pellets during the first period of heating-up process, it is necessary to study the kinetics of the reaction. In this work, the first stage of reduction of magnetite cold bond pellets, that is the reduction from Fe₃O₄ to FeO, has been investigated using an isothermal thermogravimetric method. Isothermal experiments were carried out at 750°C, 800°C, 850°C and 900°C, respectively. The results showed that the reaction was controlled by chemical reaction below 800°C, whereas, at higher temperature, it was controlled by a mixed controlled mechanism of chemical reaction and Ginstling-Brounshtein diffusion as well. Project supported by the Nonferrous Metals Industrial Corporation of China Synopsis of the author Chen Qiyuan, professor, born in 1948. Major research fields: metallurgical thermodynamics and kinetics.     

An intelligent decision support system (IDSS) in the operation process of electric furnace for cleaning slag

In this paper, the structure and function of the IDSS in the operation process of electric furnace for cleaning slag are presented and the fuzzy neural network decision model (FNNDM) in the IDSS is specially suggested. The IDSS possesses self-learning and adaptive properties, and has been used for managing and analyzing the optimal operational conditions since June 1992. Electric energy consumption has been reduced remarkably and the coefficient of recovery of cobalt and nickel has been increased. Synopsis of the first author: Peng Xiaoqi, associated professor, born in 1962, majoring research interests: modelling, optimal control and intelligent decision support system in technological process.     

Effect of water washing pre-treatment on the properties of glass-ceramics from incinerator fly ash using electronic arc furnace

Production of glass-ceramics by sintering the molten slag obtained from electric arc furnace treatment of fly ash was investigated. The effect of washing pretreatment prior to melting the fly ash on the microstructure and properties of the glass-ceramics was examined. The results show that washing pretreatment of fly ash can decrease alkali metal chloride and increase network former in fly ash, which results in the increase of peak crystallization temperature of parent glass and strengthening of properties of bending strength and chemical stability of the glass-ceramics. The optimal heat treatment temperature for parent glass of washed fly ash is 1 173 K, at which the crystalline phase of glass-ceramics is composed of gelignite (Ca2Al2SiO7) and akermanite (Ca2MgSi2O7). Glass-ceramics produced at optimal heat treatment temperature are excellent in term of the physical and chemical properties and leaching characteristics, indicating attractive potential as substitute of nature materials.     

Future resources for eco-building materials: I. Metallurgical slag

In order to make an effectivily recycle use of iron and steel slags that are main industrial wastes generated in Chinese metallurgical industry, the current technologies for reprocessing and recycling these wastes into eco-building materials were reviewed, such as preparing cement-steel slag blended cement with steel slag after metal recovery, using the fine powder of blast furnace slag (BFS) for manufacturing slag cement and high performance concrete. A further research on using these available resources more efficiently were discussed. Funded by the National Natural Sciences Foundation of China (No. 50872105) and Shaanxi Provincial Grand-Tech Project of China (No. 2008ZKC04-04)     

配料对焚烧飞灰电弧炉熔渣晶化行为的影响

将垃圾焚烧飞灰电弧炉熔融处理后的液态熔渣直接浇铸成型后热处理,运用同步热分析仪、X射线衍射仪和扫描电镜等方法,研究废玻璃和晶核剂(TiO2和Cr2O3)等辅助原料的添加对微晶玻璃晶化行为及性能影响.研究表明,适量掺加废玻璃对微晶玻璃理化性能有显著改善,晶核剂类型及添加比对微晶玻璃主晶相和晶化程度影响较大,微晶玻璃的理想原料配比为m(废玻璃)∶m(垃圾焚烧飞灰)=1∶1,晶核剂TiO2添加质量分数为3%,制成的微晶玻璃主晶相为透辉石Ca(Mg,Al)(Si,Al)2O6和少量普通辉石Ca(Mg,Fe,Al)(Si,Al)2O6,抗弯强度54.96 MPa,主要理化性能达到或优于天然花岗岩和大理石,重金属浸出浓度低于国际建材环保要求限值.     

Activity of reducing steel slag of EAF

Reducing steel slag (RSS) was mainly acquired from five electric-arc furnace (EAF) steelmaking plants (among them, the products of two plants were carbon steel and those of other plants were stainless steel) for research tests. The chemical properties, compound compositions, activities and contents of main expansive compounds were tested. The results showed that the field sampled RSS had a very high crystallinity and hydraulicity with main chemical compositions close to those of Portland cement. It can be known from the study that in case of C/S ratio higher than 2.0, the main compound compositions are C₂S, C₃S, C₂F and f-CaO. However, after the RSS was stored for six months, an obvious variation occurred with potential pre-hydration in RSS, where the SO₃ content was slightly reduced and the compressive activity index was obviously higher than that at the 28th day.