Preparation of High Activity Admixture from Steel Slag,Phosphate Slag and Limestone Powder

The problem of low disposal and utilization rate of bulk industrial solid waste needs to be solved.In this paper,a high-activity admixture composed of steel slag-phosphate slag-limestone powder was proposed for most of the solid waste with low activity and a negative impact on concrete workability,combining the characteristics of each solid waste.The paper demonstrates the feasibility and explains the principle of the composite system in terms of water requirement of standard consistency,setting time,workability,and mechanical properties,combined with the composition of the phases,hydration temperature,and microscopic morphology.The results showed that the steel slag:phosphate slag:limestone=5:2:3 gave the highest activity of the composite system,over 92%.Besides,the composite system had no significant effect on water demand and setting time compared to cement,and it could significantly increase the 7 and 28 d activity of the system.The composite system delayed the exothermic hydration of the cement and reduced the exothermic heat but had no effect on the hydration products.Therefore,the research in this paper dramatically improved the solid waste dissipation in concrete,reduced the amount of cement in concrete and positively responded to the national slogan of carbon neutral and peaking.

Research on the Low-carbon Cementitious Materials:Effect of Triisopropanolamine on the Hydration of Phosphorous Slag and Steel Slag

Cement,phosphorous slag(PS),and steel slag(SS)were used to prepare low-carbon cementitious materials,and triisopropanolamine(TIPA)was used to improve the mechanical properties by controlling the hydration process.The experimental results show that,by using 0.06%TIPA,the compressive strength of cement containing 60%PS or 60%SS could be enhanced by 12%or 18%at 28 d.The presence of TIPA significantly affected the hydration process of PS and SS in cement.In the early stage,TIPA accelerated the dissolution of Al in PS,and the formation of carboaluminate hydrate was facilitated,which could induce the hydration;TIPA promoted the dissolution of Fe in SS,and the formation of Fe-monocarbonate,which was precipitated on the surface of SS,resulting in the postponement of hydration,especially for the high SS content.In the later stage,under the continuous solubilization effect of TIPA,the hydration of PS and SS could refine the pore structure.It was noted that compared with portland cement,the carbon emissions of cement-PS-TIPA and cement-SS-TIPA was reduced by 52%and 49%,respectively.

Study on non-metallic inclusions in Al killed high strength alloy steel refined by high basicity and high Al_2O_3 content slag

Laboratory and industrial studies were carried out to investigate non-metallic inclusions in high strength alloy steel refined by high basicity and high Al_2O_3 slag.It was found that the steel/slag reaction time largely affected non-metallic inclusions.With the reaction time increased from 30 min to 90 min in laboratory study,MgO-Al_2O_3 spinels were gradually changed into CaO-MgO-Al_2O_3 system inclusions surrounded by softer CaO-Al_2O_3 surface layers.By using high basicity slag which contained as much as 41%Al_2O_3 in the laboratory study,ratio of low melting temperature CaO-MgO-Al_2O_3 system inclusions was remarkably increased to above 80%.In the industrial experiment,during the secondary refining,the inclusions changed in order of 'Al_2O_3→MgO-Al_2O_3→CaO-MgO-Al_2O_3'.Through the LF and RH refining,most inclusions could be transferred to lower melting temperature CaO-Al_2O_3 and CaO-MgO-Al_2O_3 system inclusions.

Development of Steel Slag-Based Solidification/Stabilization Materials for High Moisture Content Soil

To solve the problems of high moisture content,high viscosity,and poor engineering mechanical properties of soil,this paper using with steel slag(SS)and desulfurization ash(DS)as initial raw materials,realizing the coop-erative treatment of solid waste and solidification of silt soil.The synergistic utilization of SS and DS can reduce the production cost of curing agent and promote its own consumption.According to blended cement of various SS contents and inspected compressive strength performances,the most suitable raw materials ratio was selected.The best formula for this curing agent is cement:steel slag=3:7 with 5%DS,and its 28-day compressive strength can reach 30 MPa.The experiment shows that the effect of DS and Na_(2)SO_(4) reagent with the same quality on early compressive strength improvement of cement and SS system is not much different.In this study,the mineral composition and microstructure of different gel system blocks were characterized by XRD,SEM and EDX,and a large number of webbed structures were found in the SEM test,which was not seen in previous studies.Besides,unconfined compressive strength(UCS),water resistance,and toxic characteristic leaching procedure(TCLP)were used to evaluate silt solidified soil properties.The results demonstrated that the solidified silt could meet not only the standard of general subgrade;but also has a partial stabilization effect of heavy metal ions.

Early Intervention on the Properties of Steel Slag at High Temperature by Modifier Compound with Tailings: A Feasible Way for Comprehensive Utilization of Solid Wastes

Steel slag, a by-product of the steel production industry reaches 10%–15% of crude steel output (Motz and Geiseler, 2001). Their main application lies in the field of building materials due to some containing cementitious components, such as dicalcium silicate (C2S) and tricalcium silicate (C3S) (Waligora et al., 2010). However, blended cements with steelmaking slag show low early hydration activity, low compressive strength and bad durability because steel slag generates above 1600 ℃ with the tense and large grain size crystals, consisting of low content of C2S and C3S and high proportions of f-CaO and f-MgO compared with cement clinker.

Effect of Al content on the reaction between Fe-10Mn-xAl(x=0.035wt%,0.5wt%,1wt%,and 2wt%)steel and CaO-SiO_(2)-Al_(2)O_(3)-MgO slag

The effect of Al content(0.035 wt%,0.5 wt%,1 wt%,and 2 wt%)on the composition change of steel and slag as well as inclusion transformation of high manganese steel after it has equilibrated with Ca O-Si O_(2)-Al_(2)O_(3)-Mg O slag was studied using the method of slag/steel reaction.The experimental results showed that as the initial content of Al increased from 0.035 wt%to 2 wt%,Al gradually replaced Mn to react with Si O_(2)in slag to avoid the loss of Mn due to the reaction;this process caused both Al_(2)O_(3)in slag and Si in steel to increase while Si O_(2)and Mn O in slag to reduce.In addition,the type of inclusions also evolved as the initial Al content increased.The evolution route of inclusions was Mn O→Mn O-Al_(2)O_(3)-Mg O→Mg O→Mn O-Ca O-Al_(2)O_(3)-Mg O and Mn O-Ca O-Mg O.The shape of inclusions evolved from spherical to irregular,became faceted,and finally transformed to spherical.The average size of inclusions presented a trend that was increasing first and then decreasing.The transformation mechanism of inclusions was explored.As the initial content of Al increased,Mg and Ca were reduced from top slag into molten steel in sequence,which consequently caused the transformation of inclusions.

高温改性钢渣活化过硫酸盐降解甲基橙和苯酚的反应机制

采用高温改性钢渣活化过硫酸盐(peroxymonosulfate,PMS)降解甲基橙(methyl orange,MO)和苯酚(phenol,AR)。考察了改性钢渣投加量、PMS浓度、初始pH值、反应温度对MO和AR降解效果的影响。在改性钢渣质量浓度为9.0 g/L、PMS物质的量浓度为12.0 mmol/L、初始pH值为7.0、反应温度为25℃的条件下,反应90 min,30 mg/L MO和15 mg/L AR的降解率分别达到90.5%和100%。材料表征分析结果表明,高温改性钢渣比表面积增大、孔隙率高、催化氧化PMS性能好,且重复利用仍有较好的原位恢复性能。自由基淬灭和电子顺磁共振波谱实验说明,高温改性钢渣/PMS反应体系存在非自由基(1 O 2)和自由基(SO_(4)^(-)·和·OH),发挥了碱活化PMS和铁氧化物活化PMS的共同作用,最终将MO和AR降解为小分子物质。

钢-PVA混杂纤维高性能混凝土抗渗性能试验研究

为探究钢纤维掺量、聚乙烯醇(PVA)纤维掺量和矿粉掺量对钢-PVA混杂纤维高性能混凝土(HFHPC)抗渗性能的影响,本文开展了钢-PVA HFHPC抗渗性能试验,并对试验结果进行了极差分析、方差分析和回归分析。结果表明:对HFHPC抗渗性能的影响程度从高到低依次为钢纤维、矿粉和PVA纤维。在试验水平范围内,得出混凝土试件抗渗性能最佳水平组合:钢纤维体积掺量1.0%、PVA纤维体积掺量0.7%、矿粉质量取代率20%。当钢纤维掺量超1.0%时,HFHPC抗渗性能略有下降,但仍高于基准素混凝土。最后采用多元回归分析,建立了HFHPC渗透系数与钢纤维、PVA纤维和矿粉的预测模型。

高钛钢连铸保护渣对Al_(2)O_(3)夹杂物吸收性的研究

针对高钛钢连铸保护渣钢渣反应及吸收夹杂物的变性问题,采用热力学计算、保护渣性能测试和旋转柱法等方法,对高钛钢钢液内夹杂物的生成种类和不同温度下的生成量进行了计算,根据夹杂物的生成情况对比了传统CaO-SiO_(2)系和新开发的低反应性BaO-Al_(2)O_(3)-SiO_(2)-TiO_(2)系保护渣吸收夹杂物的性能变化,并对比了两种保护渣对夹杂物的吸收速率。热力学计算表明,研究的高钛钢中铝质量分数为0.03%、钛质量分数为0.40%,钢液中生成的夹杂物为Al_(2)O_(3),而实际生产中由于钢液局部成分差异可能有钛氧化物的生成;从保护渣吸收夹杂物前后的性能对比可知,两种保护渣的黏度和熔点均随其吸收Al_(2)O_(3)含量的增加而增加,但新开发的低反应性保护渣相对于CaO-SiO_(2)系渣的性能变化更小,其性能更稳定;由旋转柱试验可知,CaO-SiO_(2)系和BaO-Al_(2)O_(3)-SiO_(2)-TiO_(2)系保护渣对氧化铝棒的吸收速率分别在(8~12)×10^(-3) g/(cm^(2)·min)和(10~13)×10^(-3) g/(cm^(2)·min),后者对夹杂物的吸收能力更强。因此,新开发的BaO-Al_(2)O_(3)-SiO_(2)-TiO_(2)系低反应性保护渣有潜力用于更高钛含量的钢种浇铸。

碳化钢渣对沥青混合料高温稳定性的影响研究

为了研究碳化钢渣对沥青混合料高温稳定性的影响,对粒径为5~10 mm与3~5 mm的钢渣粗集料进行碳化,与以未碳化钢渣制备的AC-10钢渣沥青混合料进行膨胀性与路用性能对比。研究结果表明:当碳化时间达到6 h,2档钢渣集料的f-CaO含量均低于3.0%,最大降幅达到了51.4%,并且碳化钢渣集料从光滑的界面向复杂致密的界面演变。碳化钢渣提高了钢渣混合料和钢渣沥青混合料的高温稳定性。基于综合性能判断,建议将6 h设置为最佳碳化时间。

改性材料及其掺量对超高性能混凝土力学性能的影响

【目的】优选不同掺量的改性材料,并分析改性后的UHPC抗压强度和破坏形态,制备更加经济型的超高性能混凝土(ultra-high performance concrete,UHPC)。【方法】选取钢渣微粉、河砂、粗骨料、钢纤维作为4种改性材料,设计四因素三水平正交试验,根据正交试验结果制备9种试件;通过力学性能实验,对比分析各试件的抗压强度,优选出改性材料最佳配方并分析UHPC的破坏形态。【结果】钢渣微粉、河砂、粗骨料和钢纤维的加入量(掺量)对试件抗压强度平均值影响的极差分别为7.60、7.57、7.77、0.84,粗骨料、钢渣微粉、河砂对UHPC的抗压强度的影响较大,钢纤维对UHPC抗压强度影响较小。由正交试验结果可知,当钢渣微粉、河砂、粗骨料的加入量分别为210、855、640 kg/m^(3),钢纤维的体积分数(掺量)为1.5%,养护龄期为28 d时,经改性的UHPC抗压强度最大,为134.4 MPa。改性后的UHPC受压破坏时不会瞬间炸裂,整体形态完整。【结论】钢渣微粉和粗骨料的添加能降低改性后的UHPC制造成本,经优化4种改性材料的掺量后UHPC的抗压强度降幅较小,但韧性增强,力学性能得到保障。

高硫塑料模具钢中硫稳定性控制基础研究

基于高硫塑料模具钢典型缺陷检测和MnS析出行为研究,结合热力学计算和工业试验探索了高硫塑料模具钢精炼过程硫稳定性控制手段。结果表明,MnS夹杂是裂纹产生的原因之一。MnS在1708 K开始析出,且优先发生位错形核。MnS发生晶界形核的最快沉淀析出温度为1573 K,并在铸坯加热过程明显长大。综合高硫塑料模具钢精炼顶渣物化性质、硫容量和硫分配比的理论研究,确定最优精炼顶渣成分范围:1.55≤(w(CaO)/w(SiO_(2)))≤1.7、24%≤w(Al 2O 3)≤28%、1.4≤(w(CaO)/w(Al 2O 3))≤2.3、7%≤w(MgO)≤9%和2.5%≤∑w(FeO+MnO)≤4.0%。精炼顶渣成分与精炼工艺优化后,VD出站到中包钢中硫平均降低质量分数由108×10-6减少至30×10-6,平均Al s损由24.9×10-6减少至14.2×10-6,实现了模具钢中硫稳定性和VD至中包Al s损的大幅度改善。

精炼钢水造渣分级管控的研究与应用

结合不同钢种精炼造渣特点和钢水进精炼期间不同的生产条件,以普碳低合金钢HRB400E系列、优质碳素高碳钢65#系列以及板坯普碳钢Q235B系列为例进行研究,在原先精炼造渣的基础上进一步实施精炼钢水顶渣造渣分级管控,通过对不同钢种、不同硫含量等条件下精炼造渣分级管控措施的落实,实现精炼造渣效率有效提升、钢材质量稳步提高、精炼系统成本有效降低,进一步推动炼钢系统精细化管理向好、向深发展。

高硅钢不同脱氧工艺下精炼渣系控制

针对“转炉→RH精炼→连铸”工艺流程生产的高硅钢精炼渣精准控制的难题,借助FactSage7.2商业热力学计算软件,计算了两种不同脱氧工艺下合理的精炼渣系控制范围。采用A脱氧工艺(铝脱氧硅合金化工艺)时,合理精炼渣系控制范围为氧化钙含量为53%~55%,二氧化硅含量在15%~18%,三氧化二铝含量为25%~30%,氧化镁含量为3%~5%,碱度为3~5;采用B脱氧工艺(硅脱氧铝合金化工艺)时,合理的精炼渣系的主要成分范围为:氧化钙含量为53%~56%,二氧化硅含量为12%~17%,三氧化二铝含量为25%~30%,氧化镁含量为3%~5%,碱度为3~4.5。采用工业两种对不同脱氧工艺精炼渣系吸附夹杂能力进行分析,结果表明B脱氧工艺下夹杂物数量、尺寸分布方面均优于A脱氧工艺。

钢渣沥青混合料车辙发展规律与模型预测

开展了钢渣沥青混凝土长期高温浸水体积膨胀试验和加速加载车辙试验,结果表明,采用胶粉复合改性沥青和间断级配设计的钢渣沥青混凝土长期累计车辙深度小于5 mm,主要以追密型车辙为主。利用60℃浸水7 d可定量检验钢渣沥青混凝土浸水体积膨胀抗高温车辙性能,试验表明高温浸水后车辙深度增加22%,重载轮压导致车辙深度增加约8%,而浸水-重载耦合作用增加车辙深度32%。建立的加速加载车辙预估模型能很好地预测钢渣沥青混凝土车辙演变规律,可用于指导钢渣沥青混凝土的耐久性设计。

三七渣电渣重熔对M50高温轴承钢中夹杂物的影响

非金属夹杂物是影响高温轴承钢疲劳性能的重要因素。为了提高M50高温轴承钢的夹杂物控制水平,分析了三七渣电渣重熔精炼技术对夹杂物的影响。采用场发射扫描电子显微镜和能谱仪对夹杂物进行了表征,采用X射线荧光光谱仪分析了电渣重熔前后渣料成分的变化。在自耗电极中,夹杂物为尺寸较小的Al_(2)O_(3)-SiO_(2),其中,w[SiO_(2)]较高(平均值为29.3%),不存在聚集状夹杂物。经过电渣重熔,夹杂物转变为Al_(2)O_(3),而且存在大尺寸的簇状夹杂物;渣料中w[SiO_(2)]从1.73%增加到3.42%,同时Al_(2)O_(3)含量发生降低;钢中w[Al]从<0.0005%显著增加到0.0207%,w[Si]从0.356%降低至0.296%。基于渣-钢反应理论对电渣重熔过程的冶金反应进行了解释。钢液中的溶解Si和熔渣中的Al_(2)O_(3)在钢液和熔渣的界面发生反应,产物为溶解Al和SiO_(2)。随后溶解Al扩散进入钢液并与夹杂物中SiO_(2)发生反应,产物为溶解Si和Al_(2)O_(3)。最终使得钢中夹杂物转变为Al_(2)O_(3)。提出了控制三七渣电渣重熔M50轴承钢中夹杂物的方法。

高锰高铝钢熔体热力学研究现状

在高锰高铝钢冶炼过程中,存在钢液的洁净度较差、钢液与耐火材料(保护渣、精炼渣)反应剧烈及夹杂物控制技术不成熟等问题,严重影响钢液质量和钢锭的力学性能。针对此种情况,归纳了高锰高铝钢的热力学现状,分析了钢液与不同渣系之间的渣金反应,总结了钢液中夹杂物种类以及演变过程,以期实现该钢种更广阔的应用前景。

加压电渣重熔装备与工艺技术开发

加压电渣重熔是目前工业化制备高氮钢和高氮合金最为有效的生产路线,是当今电渣冶金领域的研究热点和前沿技术。介绍了加压电渣重熔成套设备、工艺技术发展和主要产品特点。对当前加压电渣炉装备中氮化合金加料系统和水-气动态平衡系统等核心部件进行综述;针对加压电渣重熔生产中的工艺难点,阐述了氮化合金增氮和气相增氮技术的机理和方法、新型高效发热精炼重熔渣系开发及元素精准控制等新工艺技术发展。近年来,随着国内新建的系列国产化中试规模加压电渣炉的应用和系列高氮钢产品的成功研制,我国在加压电渣重熔成套装备的自主研制和工艺技术开发上取得的较大突破,并逐步向国际先进水平迈进。同时,深入开展工业级加压电渣重熔成套装备的自主研制和工艺技术研发,保障我国航空、航天和军工等领域高端高品质特殊钢和特种合金等急需的关键材料制备,是我国发展现代电渣冶金技术的重要方向。

排水型钢渣沥青混合料路用性能研究

为了提高钢渣固废材料在道路工程建设中的利用率,采用体积换算法将不同掺量(0、25%、50%、75%)的转炉钢渣(2.36~16 mm)替代玄武岩集料,开展高温车辙、冻融劈裂、动水冲刷、体积膨胀率和渗水系数试验。结果表明:随钢渣掺量增加,8%高黏剂和0.2%聚酯纤维的排水型钢渣沥青混合料最佳油石比随之增大,混合料高温抗车辙性能、抗水损害性能及渗水性能得以提高,对体积稳定性不利,浸水体积膨胀率增大,但仍符合JTG F40—2004《公路沥青路面施工技术规范》不大于1.5%的要求。综合考虑,建议钢渣掺量控制在50%~75%,此时混合料各项路用性能较优,可实现钢渣固废材料的高效利用。

高钛焊丝钢ER70S-G冶炼工艺优化实践

高钛焊丝钢ER70S-G研发时经常出现水口结瘤、结晶器“结鱼”、铸坯夹渣等问题,尤其是铸坯夹渣导致轧制后盘条表面出现连续性锯齿状结疤缺陷,严重影响盘条表面质量。引起水口结瘤、结晶器“结鱼”的主要原因是存在TiO_(x)、TiN等高熔点非金属夹杂物。通过控制钢水中氧氮含量、使用纯净合金、降低渣中SiO_(2)活度、调整钛合金化时机及温度等手段,解决了水口结瘤、结晶器“结鱼”、铸坯夹渣等问题,将高钛焊丝钢ER70S-G连浇炉数提高至10炉,盘条成材率提高至97%,优化效果显著。