Boron removal from metallurgical grade silicon by oxidizing refining

A purification process was developed to remove impurity element boron from the metallurgical grade silicon by the electric arc furnace refining. The thermodynamic equilibria calculation and experiment to remove boron in the oxidizing atmosphere were performed and analyzed. Boron is removed as the gaseous species BxOy and BxHzOy in O2 and H2O-O2 atmosphere respectively. The equilibrium pressure of BxHzOy is 105-1010 times that of BxOy. Boron is removed and its content in silicon is reduced from 18× 10-6 to 2×10-6 in the Ar-H2O-O2 atmosphere in the electric arc furnace.

Appropriate titanium slag composition during smelting of vanadium titanomagnetite metallized pellets

The suitable titanium slag composition with high titanium content for electric furnace smelting of vanadium titanomagnetite was investigated through thermodynamics and related phase diagram analysis.According to the thermodynamic results,low-melting-point regions and MgTi2O5primary phase area in the phase diagrams,the suggested titanium slag composition for the present vanadium titanomagnetite metallized pellets should consist of50%TiO2,8%-12%MgO and13%Al2O3(mass fraction)with a binary basicity of0.8-1.2.Finally,the verified smelting experiments were conducted and successful separation of the molten iron from the titanium slag is obtained.The obtained vanadium-containing molten iron contains0.681%V and0.267%Ti,and the obtained titanium slag contains52.21%TiO2(mass fraction),in which MgTi2O5is the primary phase.The titanium resource in the final titanium slag production could be used to produce TiO2pigment by acid leaching methods.

Numerical simulation of coupling multi-physical field in electrical arc furnace for smelting titanium slag

The smelting reduction process of the ilmenite in an electric arc furnace(EAF)is a commonly used technology for producing titanium slag in the world.It has particular significance to analyze the velocity-temperature-electromagnetics multi-physical field in an EAF for improving its productivity and reducing energy consumption.A transient three-dimensional mathematical model was developed to characterize the flow,heat transfer,and electromagnetic behavior in a titanium slag EAF.For describing the electromagnetic field and its effects on velocity and temperature distribution in the furnace,magnetohydrodynamic equations and conservation equations for mass,momentum,and energy were solved simultaneously by compiling the user-defined function program.The numerical model was verified by comparing with the literature data.The results indicate that the Lorentz force is the main driving force of the velocity and temperature distribution.Moreover,the influence of input current and location of electrodes on the multi-physical field distribution was also investigated.It is found that the appropriate range of input current and diameter of pitch circle are about 30,000 A and 3000-3500 mm,respectively.The mathematical model established can characterize the multi-physical field more accu-rately than before,which can provide valuable guidance for the operation improvement and design optimization of the EAF for producing titanium slag.

Designing Evolutionary Wavelet Neural Network for Estimating Foaming Slag Quality in Electric Arc Furnace Using Power Quality Indices

In the present study,a novel approach based on an evolutionary wavelet neural network(EWNN)is proposed to estimate the slag quality in an electric arc furnace(EAF)employing power quality indices.In the EWNN,an evolutionary method is applied to train the parameters for a combination of neural networks and wavelets.I For this purpose,all of the electrical parameters for six melting processes are measured with a power quality analyzer,attached to the secondary component of an EAF transformer at a Saba steel complex,to estimate the foaming slag quality.Experimental results on various combinations of measured electrical parameters,applying the designed EWNN estimator,demonstrate that utilizing five leading indicators leads to the highest precision.The obtained 99%accuracy for estimating the foaming slag quality by EWNN compared to the other methods illustrates the proposed method's efficiency.

Synthesis of TiO_2 visible light catalysts with controllable crystalline phase and morphology from Ti-bearing electric arc furnace molten slag

TiO_2 visible light catalysts with different crystalline phases and morphologies were synthesized from titanium-bearing electric arc furnace molten slag（Ti-bearing EAF slag）by using a simple acidolysis process.The effects of the p H of the HCl solution,liquid to solid ratio（RL/S,HCl solution to the residue ratio,m L/g） and acidolysis time on the micro-morphology and crystalline phase of as-prepared TiO_2 photocatalysts were systematically investigated.The results indicated that with decreasing p H in the HCl solution and increasing RL/S,the crystalline phase and micro-morphology of the obtained TiO_2 nanostructures tended to transform from anatase type TiO_2 with spherical nanoparticle structures to rutile type TiO_2 with needle-like nanorod structures.The acidolysis time had little influence on the crystalline phase but great impact on the size of the obtained TiO_2.The growth mechanism of TiO_2 from Ti-bearing EAF slag during the acidolysis process was also discussed.In addition,the influence of RL/Son the photocatalytic properties of the synthesized nanostructured TiO_2 was studied.The results showed that the photodegradation efficiency for Rhodamine B solution could reach 91.00% in 120 min when the RL/Swas controlled at 50：1.

Separation and comprehensive utilization of valuable elements in Ti-bearing electric arc furnace molten slag

A novel route to comprehensive utilization of valuable elements such as Ti, A1, Si and Mg in Ti-bearing electric arc furnace molten slag （Ti-bearing EAF slag） was proposed. The route can be expressed as a three-step process including alkali fusion, water leaching and acidolysis. Following these processes under the optimum conditions, the recovery ratios of TiO2, Al2O3, SiO2 and MgO were about 97.5, 93.5, 27.9 and 53.5%, respectively. Meanwhile, nanostructured TiO2, NaA zeolite and Mg（OH）2 fire retardant were synthesized simultaneously by using Ti-bearing EAF slag as raw materials. In addition, the photocatalytic activity of prepared nanostructured TiO2 and the adsorption property of obtained NaA zeolite were investigated. The results showed that the photodegradation efficiency of as-prepared TiO2 was 80% for rhodamine B and the adsorption efficiency of NaA zeolite was 61% for Cu2＋ under the optimum conditions.

铁浴条件下电炉粉尘球团的熔融与分离行为

为了提高对含锌电弧炉粉尘(EAFD)的利用效率,实验研究EAFD球团在铁浴条件下的还原熔化行为。定义铁液滴球形度作为判断其凝聚的标准,然后探讨铁液滴直径和球形度之间随时间变化的关系。根据实验最终建立EAFD颗粒的熔化和分离行为。结果表明,在铁浴条件下,EAFD球团的Zn去除率在5.0 min时达到99%以上,但在15.0 min时金属渣分离还没有完成。由于成分的波动,在EAFD球团中形成几个区域的液态渣,然后液态渣不断增加,直到球团完全熔化。球形度>65%、直径>500μm的Fe液滴的数量随着时间的推移而减少,大直径的Fe液滴先完成分离。渣铁分离过程如下:在布朗运动下Fe液滴在渣中形成,之后Fe液滴直径在马兰戈尼效应下增加,Fe液滴在渣中下降速度符合斯托克斯定律。

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 and improving hot metal temperature and melting premelted slag; secondly, 30wt% hot metal was charged into EAF with high basicity refining slags from ladle furnace （LF）-vacuum degassing furnace （VD） refining process. The results show that the hot metal charging ratio can reach to about 65wt%-70wt% for the new EAF steelrnaking process; meanwhile, the tap-to-tap time of a 50 t EAF can shorten by 5-10 min, the electricity consumption can decrease by 35-50 kW·h/t, the lime consumption can reduce by 10.5 kg/t of molten steel, and the content of harmful heavy metals in molten steel can be easily controlled to less than the upper limits of aimed steel specification or grade compared with the traditional EAF steelmaking process. In addition, the dephosphorization ability shows a slight strengthening, however, a small degree of lessening for desulphurization ability is observed for the new EAF steelmaking process, but the weakness of desulphurization ability cannot become an obstacle to its further application since a stronger desulphurization ability can be achieved during secondary refining of LF coupled with VD after EAF steelmaking process.

熔融电炉渣齿轮粒化实验

电炉炼钢过程中的副产物熔融电炉渣含有高品位热能.为了有效回收该热能,提出了采用齿轮将熔融电炉渣粒化为渣粒的技术设想,并利用实验的方法研究了不同齿轮结构下熔渣温度、熔渣下落高度、熔渣流量、流股数量和齿轮转速对电炉渣粒平均粒径和粒径分布的影响.结果表明:直齿轮粒化器能够粒化出尺寸更小的电炉渣粒;熔渣流量和齿轮转速是影响电炉渣粒平均粒径的主要因素;随着熔渣流量的增加,渣粒平均粒径呈增大趋势,较大粒径渣粒的占比上升;随着齿轮转速的增加,渣粒平均粒径呈减小趋势,较大粒径渣粒的占比下降;随着流股数量的增加,渣粒的平均粒径和粒径分布几乎不变.

大型单相电渣炉的起弧控制

对大型单相电渣炉的技术特性及起弧控制进行了简单介绍,总结了大型电渣锭起弧方面的控制措施,旨在提高大型电渣锭的起弧成功率。该措施对于企业生产及开展相关研究具有一定的参考价值。

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

The valuable metals in the dust can be recycled by mixing it with reducing agent carbon and lignosulfonate as the binder to make pellets, then returning the pellets to electric arc furnace (EAF) and adding ferro silicon. Part of valuable metals in the dust is reduced by carbon and part of them reduced by ferro silicon for the economical consideration. The reduced metals get into the steel in the stainless steel or special steel production. But the sulfur in the lignosulfonate may affect the quality of produced steel, which is dependent on the status of the smelting slag. The experiments were conducted in the way of changing the ratio of start iron, pellets, ferro silicon and lime. The content of the slag was checked by XRF for the calculation thermodynamics study. The active concentrations of materials in the slag, the slag abilities of oxidation and sulfur removal in EAF dust reduction process were determined by thermodynamics calculation study on CaO MgO FeO Fe 2O 3 SiO 2 S slag at 1 550 ℃. The oxidation ability of slag can be expressed as N (FetO)= N (FeO)+6 N (Fe 2O 3)+8 N (Fe 3O 4). The sulfur removal ability is dependent on the amount of added ferro silicon and the basicity of the slag. The calculation thermodynamics model was set up and it could be applied to the practical production.

Slag foaming experiments in EAF for stainless steel production

The foaming slag practice can effectively solve the problems existing in EAF smelting of stainless steel, such as high electrical consumption ,high refractory consumption and long tap to tap time. In this paper, theoretical analyses were made on the technical difficulties and development feasibility of the technology. Slag foaming experiments were performed in a 10t EAF where crude stainless steel with a Cr content of 13% - 15% and a carbon content of 1.5% - 2.5% was smelted and special foaming pellets were added to release additional gas for better foaming. Good foaming slag was observed with the electric arc fully covered by the foam when the content of Cr2O3 is between 7% - 12%. The industrial scale experiments were performed in a 110 t EAF by the use of the same foaming pellets. Compared with the traditional operation, these experiments resulted in better foaming effects.

改性钢渣-橡胶复合功能材料导热性能分析

钢渣作为炼钢过程中的副产物,具有产量大、难处理、用途单一等特点,为解决上述问题,采用钢渣助磨改性剂(含乙二醇、三乙醇胺和无水乙醇)分别处理北区热闷渣、南区热闷渣、电炉渣和风淬渣制备改性钢渣微粉,再与炭黑等复合形成改性钢渣-橡胶复合功能材料。利用导热系数仪测试其导热系数,并提出有效体积分数因子α对Maxwell-Educken模型进行修正,研究结果表明:当钢渣助磨改性剂与电炉渣的质量比为1.5%、改性电炉渣替代炭黑比例为40%时,改性电炉渣-橡胶复合功能材料的导热系数为0.1869 W/(m·K),保温性能最好,且修正后的Maxwell-Educken模型对导热系数的理论计算值更为准确;同时,热氧老化前后,其交联密度低于未添加改性电炉渣的橡胶复合功能材料,说明改性电炉渣的加入破坏了橡胶与炭黑等物质形成的三维网状结构,提高了其保温性能。研究成果可为钢渣的高值化利用研究提供借鉴。

电炉钢渣用作混凝土骨料的研究进展

钢渣用作混凝土骨料时应非常慎重。从安定性和重金属浸出风险这两个角度分析了电炉钢渣用作混凝土骨料的可行性,总结了电炉钢渣对混凝土工作性、力学性能、耐久性能和界面过渡区的影响,介绍了电炉钢渣在混凝土工程中的应用现状,针对电炉钢渣用作混凝土骨料存在的不足,对其未来研究方向进行了展望,可为电炉钢渣在混凝土中的深入应用提供参考。

喷吹微粒脱磷法在130 t电弧炉炼钢中的应用

在130 t电弧炉上进行了复合喷吹剂喷吹微粒脱磷的实践应用。设计了电弧炉氧化期脱磷渣系的组成,炉渣碱度控制在2.2~2.8,氧化铁含量控制在15%~20%。并以氮气为载体喷吹按照一定比例配制的碳粉(15%~20%)、CaO粉(40%~60%)、MgO粉(25%~30%)、CaC粉(5%~10%)的复合粉剂。40Cr、45钢、20CrMnTi和60Si2Mn等钢采用喷吹复合喷吹剂冶炼工艺后,加快了熔剂的反应面积,提高了成渣速度,各项生产指标得到了改善,其中吨钢电耗降低90 kWh/t,吨钢钢铁料消耗降低9.3 kg/t,吨钢熔剂消耗减少4.8 kg/t,生产率提高5%~6%,吨钢综合生产成本降低了25元/t。

还原精炼条件下炉渣的泡沫化

针对电弧炉还原期和ＬＦ炉精炼过程中造泡沫渣的工艺特点，向精炼渣中加入发泡剂使炉渣泡沫化。通过在实验室内对各种碳酸盐、氯化盐发泡材料的发泡性能研究，得出几点结论：①碳酸盐和氯化盐中，ＣａＣＯ_３，ＣａＣｌ_２的发泡性能较好；②向ＣａＣＯ_３中加入Ｎａ_２ＣＯ_３会使ＣａＣＯ_３的发泡效果明显降低；③当起泡时间相差较大的几种发泡剂混合后，发泡过程中起泡高度会出现多个峰值；④采用以ＣａＣＯ_３为主要原料的发泡剂产品，发泡效果好，原料资源丰富，成本低廉。

宝钢300tLF渣精炼技术的开发与应用

对 L F合成渣脱硫、脱氧技术理论和埋弧精炼基本方法进行了分析。介绍了宝钢 30 0 t L F脱硫合成渣、脱氧合成渣和埋弧精炼技术的开发过程及应用效果。采用所开发的上述技术 ,能够批量生产 [S]≤ 10× 10 - 6的超低硫钢和 T [O]≤ 15× 10 - 6的低氧钢 ,并实现了 L F全程埋弧精炼。

电弧炉炼钢炉渣成分实时预报模型

为了实现冶炼过程中对炉渣成分的实时预测,给电弧炉炼钢过程中加料等工艺操作提供帮助,对影响炉内炉渣成分的因素(炉内反应、加料与流渣)进行了研究,构建了电弧炉炼钢炉渣成分实时预报模型.结果显示,该模型能够实时预测炉内炉渣质量和成分变化,预报炉内铁元素氧化状况,可为冶炼过程中添加辅料与流渣等工艺操作提供指导作用.通过与现场炉渣取样检测结果进行对比,得到炉渣中CaO、SiO2和FeO实测成分与模型预测成分的平均相对误差分别为12.66%、11.17%和19.16%.

埋弧法精炼技术的应用

在电弧炉还原期的使用结果表明，开发出的埋弧渣产品，能使炉渣高度增大一倍，平均脱Ｓ率为７４．９％，并有一定的脱Ｐ效果。在钢包炉（ＬＦ）上的使用表明，渣厚增大一倍以上；升温速度由１～２℃／ｍｉｎ提高到３～４℃／ｍｉｎ；平均精炼时间节约了１２ｍｉｎ；钢包寿命显著提高；节电３．７ｋＷｈ／ｔ钢；平均脱Ｓ率４５％。