不锈钢渣熔融还原中铬在铁浴和熔渣间的分配行为研究

通过正交试验考察不锈钢渣铁浴熔融还原中反应温度、炉渣碱度、渣中Al2O3含量及铁水初始铬含量对铬在铁浴和碱性炉渣间分配行为的影响。试验在石墨坩埚内进行,还原剂为碳饱和铁水中的碳。试验结果表明,对影响渣中铬还原因素的显著性顺序依次为:炉渣碱度>渣中Al2O3含量>铁水初始铬含量>反应温度。此外采用模式识别方法对试验样本进行聚类分析和优化,以获得对渣中氧化铬还原的最佳参数。     

Reduction of synthetic stainless steel slags by aluminium

One of the most efficient ways to eliminate the harm of chromium oxide in stainless steel slag is to reduce chromium oxide in stainless steel slag using aluminium. In the present work, the Al reduction of synthetic CaO–SiO₂–Al₂O₃–MgO–Fe₂O₃–Cr₂O₃ stainless steelmaking slags at different conditions, including temperature, slag basicity and Al amount was investigated to get optimal conditions for the reduction and the metal–slag separation. It was found that the agglomeration of metal droplets and metal–slag separations were improved by increasing temperature. The reduction degrees of SiO₂, Fe₂O₃ and Cr₂O₃ were enhanced with increasing basicity of slag. The addition of CaF₂ in slag leads to better agglomerations of metal droplets and metal–slag separations. The highest reduction degree of chromium could reach 99% in slag with basicity of 2 at 1873 K.     

Fe-Cr-C金属与CaO-SiO2-MgO-(Al2O3)-CrOx渣反应平衡时渣中Cr含量预测

摘要：冶炼不锈钢或高温还原法处理不锈钢工业典型固废时,渣金反应终点渣中残Cr含量 (w(Cr)slag)的高低是评价还原操作经济性以及残渣是否无害的关键参数。借助热化学软件FactSage,计算了Fe-Cr-C熔体中［Cr］的活度、反应体系的氧势及CaO-SiO2-MgO-(Al2O3)-CrOx-O2熔渣的等活度图,并构建了残Cr预测模型,综合讨论了平衡态时金属成分(［Cr］、［C］含量)、熔渣成分(二元碱度、MgO、Al2O3)以及温度对渣中残Cr含量的影响,得到了不同条件下渣中残Cr含量的极限值。实验室试验结果与模型预测结果基本一致,验证了模型的可靠性。     

LF精炼渣碱度变化对304不锈钢夹杂物成分的影响

采用氧氮分析仪、扫描电镜、金相显微镜等分析手段,系统研究LF精炼渣系对304系不锈钢全氧质量分数wT[O]、夹杂物数量、尺寸及成分的影响。研究结果表明,当LF精炼渣碱度由1.5升高至2.6时,LF出站溶解氧质量分数w[O]由11.6×10~(-6)降低至4.8×10~(-6),铸坯wT[O]由47×10~(-6)降低至24×10~(-6),铸坯夹杂物总数量降低,但当量直径不大于10μm的夹杂物所占比率由77.7%增加至95.1%。热力学计算结果表明:在钢液中各元素达到平衡状态时,渣系碱度越高,低熔点夹杂物2MgO·2Al_2O_3·5SiO_2生成区域越小,MgO·Al_2O_3尖晶石类夹杂物生成区域越大,与生产试验结果一致。随着LF炉渣碱度升高,铸坯夹杂物成分中MgO和Al_2O_3的质量分数分别升高了14.4%和9.1%,当碱度不大于1.9时,铸坯中不会存在镁铝尖晶石。     

304不锈钢不同精炼渣碱度下夹杂物的演变

 为了提高304不锈钢的产品质量,结合生产实际,利用热力学计算和扫描电镜能谱分析方法, 研究了硅脱氧条件下,LF精炼渣碱度对304不锈钢在LF精炼、连铸过程夹杂物变化规律的影响。试验结果表明,随着冶炼过程进行,全氧质量分数和夹杂物数量依次减小。304不锈钢采用1.75高碱度炉渣,可以得到较低的全氧质量分数和夹杂物数量,但是夹杂物中Al2O3质量分数高,夹杂物熔点高。采用1.53低碱度炉渣,钢液中全氧质量分数较采用高碱度炉渣高,但是夹杂物中CaO、Al2O3质量分数相对较低,SiO2和MnO质量分数较高,夹杂物熔点低。针对304不锈钢产品可以采用不同的生产工艺路线来满足产品的不同需求。     

不锈钢渣高温改性?析晶调控解毒研究现状及发展趋势

截止到目前,钢铁工业普通固废（高炉铁渣）循环利用技术取得了重要进展,但仍存在固废顽疾亟需处理。不锈钢冶炼产生的含铬（Cr）渣长期以来缺乏有效的无害化处置方法,环境隐患巨大。国内外专家学者通过添加还原物质、高温调质及调节冷却方式等以改变渣中铬元素的赋存状态,控制Cr6+的溶出,进而实现不锈钢渣的解毒。其中,高温改性?析晶调控方法可以通过调整钢渣组分和控制温度制度促进含铬尖晶石相的形成和长大,提高铬元素在尖晶石相中的富集程度,有望成为最有效且安全的无害化处理技术,在近些年得到快速发展。本文从不锈钢渣高温改性?析晶调控解毒的热力学机理和结晶动力学原理出发,针对不锈钢渣的高温调质改性、解毒方面的研究进展进行了综述。基于高温调质?选择性析晶的核心问题,重点阐述了改善解毒效果的方法和措施。另外,针对不锈钢渣高温改性?析晶调控解毒存在的问题提出了今后的发展方向。      

Effect of cooling regime on phase transformation and chromium enrichment in stainless-steel slag

Cooling regime of stainless-steel slag has a great influence on the migration rule of chromium. Effect of cooling rate on chromium distribution in CaO–SiO₂–MgO–Al₂O₃–Fe_xO–Cr₂O₃ system has been studied by FactSage, XRD and SEM-EDS in this paper. Results showed that the main phases in stainless-steel slag are spinel, bredigite, wustite, lime and periclase. Chromium was enriched in the stable phases. With the decrease in cooling rate, the size of chromium-rich phase increased relatively while chromium content in spinel phase reduced. Rapid cooling was favourable to the chromium enrichment in spinel phase in high basicity (high than 2.0) stainless-steel slag.     

不锈钢渣六元渣系模型研究

建立了不锈钢渣的CaO-MgO-FeO-SiO2-Al2O3-Cr2O3六元渣系活度模型.基于共存理论的活度模型得出了渣系中主要组分及复合氧化物在不同条件下的活度.结果表明,原渣系中的Cr2O3主要形成了不稳定的CaCr2O4,在自然环境中可以被氧化为酸溶性的CaCrO4,从而释放出强毒性的Cr6+,因此不锈钢渣具有潜在毒性.温度、碱度以及渣中MgO、FeO都对Cr2O3进入尖晶石相中从而实现稳定解毒有影响.通过调节渣系成分和处理条件能够基本实现含铬废渣的无公害化.     

二元碱度和Al_2O_3对CaO-SiO_2-FeO-Fe_2O_3-P_2O_5-Al_2O_3-MgO-MnO钢渣中磷酸盐富集的影响

以八元CaO-SiO_2-FeO-Fe_2O_3-P_2O_5-Al_2O_3-MgO-MnO钢渣体系为研究对象,结合热力学计算和实验检测,分析了二元碱度B和Al_2O_3含量对八元钢渣系中磷酸盐富集行为的影响。结果表明:钢渣二元碱度和Al_2O_3含量直接影响钢渣中f-C2S的生成量,进而影响磷酸盐富集相nC_2S-C_3P内P_2O_5的含量。随着二元碱度从1.3提高至2.5,磷酸盐富集率增大,磷酸盐富集相nC2S-C3P中的P_2O_5含量呈现先迅速增大(B从1.3至1.7),然后逐渐减小(B从1.8至2.5)的趋势。当二元碱度和Al_2O_3质量分数分别控制在1.7和12%时,即当满足四元碱度R为1.23时,此八元钢渣体系有较好的磷酸盐富集效果,磷酸盐富集相nC_2S-C_3P内的P_2O_5的质量分数可以达到24.23%。     

不锈钢粉尘内配煤团块高温自还原过程中金属铁的聚集

用不锈钢生产中的高碱度二次粉尘制备内配煤团块,在高温下自还原获得含铬、镍的金属铁粒.研究影响铁粒聚集长大的因素.研究表明:(1)内配煤团块的渣相碱度(w( CaO)/w( SiO2))小于2.8时,还原产物冷却过程中渣相与金属铁粒才能自然分离.碱度越低,渣量越大,越不利于金属铁聚集长大;(2)提高内配碳比,渣相残碳量明显升高,渣中过量的碳阻碍金属相聚集长大;(3)提高还原温度,直接还原铁的海绵状结构解体,逐渐聚集成颗粒状金属铁.还原温度越高,越有利于金属铁的聚集长大     

15-5PH不锈钢大型锻件冶炼脱氧工艺研究

摘要：以实际工艺流程50t EBT-VOD-LF-VC冶炼15-5PH不锈钢为背景,通过FactSage 8.0和经典Wagner模型研究冶炼硅铝复合脱氧过程中钢液中的铝含量、炉渣组成以及冶炼温度等因素对钢液中氧含量的影响进行了热力学研究。结果表明：Al-Si复合脱氧为15-5PH不锈钢冶炼过程中的最佳脱氧工艺,为了保证脱氧的冶炼效果,应控制钢液中的酸溶铝的质量分数在0.015%左右;降低冶炼温度有利于降低钢液平衡氧含量;考虑炉渣的物理性能和钢渣界面平衡反应得出脱氧工艺的最优炉渣成分,碱度为2.5~3.0,w（(Cr2O3)）=0.5%,w（(Al2O3)）=20%,w（(MgO)）=5%,w（(CaF2)）=5%;经过工艺优化后生产的15.5PH不锈钢中氧含量明显降低,均满足产品要求,炉渣碱度对平衡氧含量和实际生产全氧含量的影响规律基本相同。     

铬矿熔融还原不锈钢直接合金化的热力学分析

 针对铬矿熔融还原法不锈钢直接合金化工艺中的热力学问题,利用热力学参数状态图、化学反应等温方程式等进行了理论分析和计算,为在转炉中用铬矿实现钢的直接合金化的热力学可行性提供了理论依据。结果表明：转炉内用铬矿熔融还原直接合金化是可行的,且必须外加还原剂;增加渣中(Cr2O3)含量,适当提高碱度,可以降低(Cr2O3)开始还原温度;渣中铬氧化物以(CrO)形态存在时,开始还原温度较低;(FeO)含量越低,(Cr2O3)开始还原温度越低。     

齿轮钢中非金属夹杂物控制技术研究

为了降低钢的T[O]含量和生成较低熔点的非金属夹杂物以改善合金结构钢的抗疲劳破坏性能,在炉外精炼中采用了高碱度和高Al2O3含量的渣系.研究发现LF和RH精炼结束时钢液T[O]含量均随炉渣碱度增加而降低,在炉渣Al2O3含量低于25%时,T[O]随炉渣Al2O3含量减少而降低,而当炉渣Al2O3超过25%后,T[O]则随炉渣Al2O3含量增加而降低.精炼过程钢液中夹杂物按"Al2O3系夹杂物→MgO-Al2O3系夹杂物→CaO-MgO-Al2O3系夹杂物"顺序发生转变,其中MgO-Al2O3系夹杂物向CaO-MgO-Al2O3系夹杂物的转变是由外向内逐步进行的,转变速度相对较慢,因而致使LF结束时钢中仍存在许多尚未转变的Mgo-Al2O3系夹杂物.钢液T[O]对夹杂物转变有显著影响,降低T[O]含量有利于生成较低熔点的CaO-MgO-Al2O3系夹杂物.     

Activity of Chromium Oxide in CaO‐SiO2 based Slags at 1873 K

Thermodynamic properties of chromium oxides in molten slags are very important for optimization of stainless steel refining processes as well as reduction processes of chromium ores. The solubility of chromite into molten slags has been found to vary drastically with oxygen partial pressure and slag composition in the former studies by the authors. In the present study, activity data and redox equilibria of chromium oxides measured under moderately reducing conditions, P_O2= 6.95×10^?11 atm, at 1873 K are summarized. For the CaO‐SiO₂‐CrO_x system, the activity coefficient of chromium oxide increased with increasing basicity and the optimized slag composition for stainless steel refining is assessed as that saturated with CaCr₂O₄ and Cr₂O₃ using the phase relations determined. On the other hand, the presence of MgO and Al₂O₃ brings about different behaviour of chromium oxide activity and redox equilibria and the 44 mass per cent CaO ‐ 39 mass per cent SiO₂ ‐11 mass per cent Al₂O₃ ‐ 6 mass per cent MgO slag is recommended to reduce the chromium oxidation loss in the practical stainless steel refining process at 1873 K.     

坩埚材质及顶渣成分对帘线钢夹杂物成分的影响

 使用碳管炉熔炼帘线钢72A,研究不同材质坩埚及不同成分顶渣对钢中夹杂物的影响。结果表明,MgO坩埚冶炼的帘线钢中夹杂物变形率高于ZrO2、SiO2、Al2O3坩埚。采用SiO2坩埚冶炼时,钢中夹杂物几乎不变形,其SiO2含量大于90%(质量分数,下同)。采用Al2O3坩埚,个别夹杂物Al2O3的含量达到40%左右,不适合冶炼帘线钢。钢中夹杂物成分进入较低熔点区(即不大于1500℃的区域)的条件为：采用MgO坩埚,顶渣碱度为10时,wAl2O3≤3%,或顶渣碱度为09时,wAl2O3为9%;采用ZrO2坩埚时,顶渣碱度为11~12时,wAl2O3为3%。     

Separation and Recovery of Phosphorus from P-bear-ing Steelmaking Slag

In order to recycle the phosphorus from P-bearing steelmaking slag, the influences of magnetic field inten- sities, slag particle sizes and slag compositions were investigated by magnetic separation experiments. SiO2, A1203 and TiO2 melting modification of converter slag was made respectively and phosphorus-rich phase was extracted by magnetic separation. The results show that MgO, MnO, Na2 0 and CaF2 have little effect on the phosphorus recovery, whereas the addition of SiO2, Al2 03, and TiO2 has great effect on phosphorus enrichment in slag and magnetic separation. With adding the reagent of SiO2 Al2 03 and TiO2, recycled non-magnetic substances are increased obviously and P2 05 content in nowmagnetic substances and phosphorus recovery rate are also increased. The phosphorus recovery rates of modified slag No. 8 （SiO2 modification）, slag No. 10 （AI2 03 modification） and slag No. 11 （TiO2 modification） are 84.75 %, 82.16 % and 74.46 %, respectively. Then, most of phosphorus was recycled.     

电弧炉冶炼不锈钢低氟泡沫渣实验

 结合宝钢电弧炉冶炼不锈钢的生产实际，在实验室中频感应炉上对选定低氟渣系进行发泡性能实验，得出了影响熔渣发泡性能因素的主次顺序：碱度＞Cr2O3＞MgO＞Al2O3。模式识别对发泡剂成分的优化具有较高的可靠性。用旋转柱体法对现场取样的炉渣粘度进行了测定，并在1 650 ℃时对粘度和成分作多元线性回归，利用该回归方程进行预测，结果表明预测值与实测值吻合得很好，相对误差在2%以下，可为生产提供指导。     

Effects of silica addition on chromium distribution in stainless-steel slag

The present study was aimed at highlighting the effect of silica on chromium distribution and enrichment in certain stainless-steel slag when basicity ranged from 0.96 to 1.96. Industrial slag samples of the CaO–Al₂O₃–MgO–SiO₂–CrO_X–Fe_XO system were investigated with different silica addition contents and soaked at the targeted regime. X-ray diffraction, electron probe micro-analyzer with wavelength-dispersive X-ray spectrometer, as well as Fourier-transform infrared spectroscopy and NIH ImageJ software were used for sample characterisation. FactSage version 6.4 was employed to calculate phase equilibria at 1200°C for the slag system to understand the crystallisation procedure. Results indicated that chromium was enriched in CaCr₂O₄ at high basicity, but in spinel at lower basicity. The spinel phase increased in size and chromium distribution with Fe(II) participated in growth with the decrease in depolymerisation of the slag structure.     

GCr15轴承钢LF精炼过程脱硫能力的热力学评价

通过现场取样分析和热力学计算,评价了工业化生产GCr15轴承钢LF精炼工序的脱硫能力.分析了精炼温度、钢中酸溶铝含量、精炼渣的光学碱度对LF精炼过程硫分配比的影响.由于实际精炼过程中脱硫反应未达到平衡,实际测得的硫分配比低于理论计算值.得到了精炼温度为1 830～1 855 K,钢中酸溶铝的质量分数为0.020％～o.050％,精炼渣光学碱度在0.760～0.795范围内,精炼温度、钢中酸溶铝、渣的光学碱度及渣中Al2O3、SiO2含量对硫分配比影响的回归方程,该方程可作为实际生产条件下LF精炼工序脱硫能力的评价依据.根据回归方程,设计了改变精炼渣组成的3因素4水平正交实验,分析了精炼渣二元碱度R2及Al2O3和SiO2含量对硫分配比的影响,得出渣-钢间最优硫分配比的精炼渣组成(质量分数)为:CaO 55.11％,Al2O3 30％,SiO26.89％,MgO 8％,光学碱度为0.777.     

304不锈钢连铸过程中结晶器渣圈形成机制

 在连铸过程中,结晶器易结渣圈是造成铸坯产生缺陷的主要原因之一。对304不锈钢板坯连铸过程中结晶器保护渣原渣、距开浇60 min时的液渣和渣圈的化学组成、理化性能、结晶矿相以及渣圈形貌结构进行对比分析。结果表明,连铸过程中TiO2和Cr2O3从钢液进入液渣生成高熔点氧化物,使液渣和渣圈的完全熔化温度和黏度显著增大,碱度、转折温度降低。液渣与渣圈的物相以枪晶石和钙铝黄长石为主。高熔点相钙铝黄长石的大量析出以及TiO2和Cr2O3进入液渣使液渣黏度增大是渣圈形成并长大的重要原因。