Study on Foaming Behaviour of Molten Slag during Smelting Reduction with Iron Bath

The molten slag in smelting reduction with iron bath has peculiar behaviour for its high FeO concentration. Slag foaming is effected by the concentration and reduction rate of FeO, basicity of slag and temperature. Addition of granulated coke can greatly decrease slag foaming extent in the process of smelting reduction with iron bath. The anti-foaming capacity of granulated coke is the best when the ratio of coke used for coke layer to total coke used in smelting reduction is controlled at about 20%.

Influence of aluminium nitride as a foaming agent on the preparation of foam glass-ceramics from high-titanium blast furnace slag

To effectively reuse high-titanium blast furnace slag （TS）, foam glass-ceramics were successfully prepared by powder sintering at 1000℃. TS and waste glass were used as the main raw materials, aluminium nitride （AIN） as the foaming agent, and borax as the fluxing agent. The influence of the amount of A1N added （lwt%-5wt%） on the crystalline phases, microstructure, and properties of the produced foam glass-ceramics was studied. The results showed that the main crystal phases were perovskite, diopside, and augite. With increasing A1N content, a transformation from diopside to augite occurred and the crystallinity of the pyroxene phases slightly decreased. Initially, the aver- age pore size and porosity of the foam glass-ceramics increased and subsequently decreased; similarly, their bulk density and compressive strength decreased and subsequently increased. The optimal properties were obtained when the foam glass-ceramics were prepared by adding 4wt% AIN.

Influence of CeO_2 addition on the preparation of foamed glass-ceramics from high-titanium blast furnace slag

Foamed glass-ceramics doped with cerium oxide（CeO_2）were successfully prepared from high-titanium blast furnace slag by one-step sintering.The influence of CeO_2 addition（1.5wt%–3.5wt%）on the crystalline phases,microstructure,and properties of foamed glass-ceramics was studied.Results show that CeO_2 improves the stability of the glass phase and changes the two-dimensional crystallization mechanism into three-dimensional one.XRD analysis indicates the presence of Ca（Mg,Fe）Si_2O_6 and Ca（Ti,Mg,Al）（Si,Al）_2O_（6 ）in all sintered samples.Added with CeO_2,Ti CeO_4 precipitates,and crystallinity increases,leading to increased thickness of pore walls and uniform pores.The comprehensive properties of foamed glass-ceramics are better than that of samples without CeO_2.In particular,the sample added with a suitable amount of CeO_2（2.5wt%）exhibits bulk density that is similar to and compressive strength（14.9 MPa）that is more than twice of foamed glass-ceramics without CeO_2.

Effect of sintering temperature on the microstructure and properties of foamed glass-ceramics prepared from high-titanium blast furnace slag and waste glass

Foamed glass-ceramics were prepared via a single-step sintering method using high-titanium blast furnace slag and waste glass as the main raw materials The influence of sintering temperature(900–1060℃) on the microstructure and properties of foamed glass-ceramics was studied. The results show that the crystal shape changed from grainy to rod-shaped and finally turned to multiple shapes as the sintering temperature was increased from 900 to 1060℃. With increasing sintering temperature, the average pore size of the foamed glass-ceramics increased and subsequently decreased. By contrast, the compressive strength and the bulk density decreased and subsequently increased. An excessively high temperature, however, induced the coalescence of pores and decreased the compressive strength. The optimal properties, including the highest compressive strength(16.64 MPa) among the investigated samples and a relatively low bulk density(0.83 g/cm^3), were attained in the case of the foamed glass-ceramics sintered at 1000℃.

Foaming Behavior in Molten Slag Caused by Decomposition of Carbonate Minerals

The average foam life is proposed as an index to the foaming behavior in molten slag. The molten slag system of Na2B4O7-CaO-MgO is foamed by the gas from the thermal decomposition of carbonate minerals as the foamer. The experimental results show that foamer type and particle size have influence upon the average foam life of slag. The concentration of CaO and MgO in molten slag not only varies the physical properties of melt but also influences directly the decomposition rate of carbonate and the bubble size of gas, thus playing an important role in foaming and to foam stability of slag.

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.

Tests on Alkali-Activated Slag Foamed Concrete with Various Water-Binder Ratios and Substitution Levels of Fly Ash

To provide basic data for the reasonable mixing design of the alkali-activated (AA) foamed concrete as a thermal insulation material for a floor heating system, 9 concrete mixes with a targeted dry density less than 400 kg/m3 were tested. Ground granulated blast-furnace slag (GGBS) as a source material was activated by the following two types of alkali activators: 10% Ca(OH)2 and 4% Mg(NO3)2, and 2.5% Ca(OH)2 and 6.5% Na2SiO3. The main test parameters were water-to-binder (W/B) ratio and the substitution level (RFA) of fly ash (FA) for GGBS. Test results revealed that the dry density of AA GGBS foamed concrete was independent of the W/B ratio an RFA, whereas the compressive strength increased with the decrease in W/B ratio and with the increase in RFA up to 15%, beyond which it decreased. With the increase in the W/B ratio, the amount of macro capillaries and artificial air pores increased, which resulted in the decrease of compressive strength. The magnitude of the environmental loads of the AA GGBS foamed concrete is independent of the W/B ratio and RFA. The largest reduction percentage was found in the photochemical oxidation potential, being more than 99%. The reduction percentage was 87% - 93% for the global warming potential, 81% - 84% for abiotic depletion, 79% - 84% for acidification potential, 77% - 85% for eutrophication potential, and 73% - 83% for human toxicity potential. Ultimately, this study proved that the developed AA GGBS foamed concrete has a considerable promise as a sustainable construction material for nonstructural element.

大掺量钢渣微粉-水泥泡沫轻质土的孔结构表征及其对力学性能的影响

为研究大掺量钢渣微粉-水泥泡沫轻质土中孔隙结构与力学性能的关系,采用计算机断层扫描技术(X-CT)分析不同钢渣微粉掺量、水灰比、湿密度等级条件下泡沫轻质土孔结构特征参数的变化规律,并运用灰色关联方法分析孔结构特征参数与抗压强度之间的关系。研究结果表明,钢渣微粉掺量增加、湿密度等级降低f都将导致孔隙率增大、球度值降低、孔径增大;球度值、孔径随水灰比增大而增大,孔隙率则与水灰比成负相关关系;主要孔隙类型为球状孔隙且球度值与孔体积呈负相关关系;孔结构特征参数均与泡沫轻质土抗压强度关系紧密,其中孔隙率对强度影响最大,且孔径小于0.5 mm和0.5~1 mm之间的孔隙对抗压强度影响最大;孔隙形状中球状孔隙灰关联度最大且越近似球状的孔隙对抗压强度影响越大。研究结果对钢渣废弃物资源化循环利用有一定借鉴意义。

生白云石用作转炉炼钢压渣剂的生产实践

为解决现有技术中,转炉吹炼终点炉渣泡沫化程度严重,进而影响炼钢设备和作业人员安全,转炉钢铁料消耗增加以及冶炼周期延长等技术问题,利用生白云石用作压渣剂吸热分解,反应生成大量CO_(2)气体,增加了钢中气体形核中心,降低了CO气泡的形成压力,在氮气吹扫辅助搅拌作用下,有利于渣中CO气体在短时间内排出,达到快速消泡的目的。另外,白云石遇热分解后生成的CaO和MgO为高熔点物质,降低了炉渣温度,提高了炉渣的碱度、黏度和熔点,有利于改善脱磷条件和溅渣效果,降低了炉衬侵蚀速度。与未使用白云石压渣消泡工艺相比,转炉倒炉时间缩短36.67%,溅渣时间缩短60s,耳轴、炉底部位炉衬侵蚀速度降低0.11mm/炉左右,为转炉实现高效率冶炼生产提供保障。

煤矸石制备发泡陶瓷的性能研究

为高附加值资源化利用煤矸石和钢渣,以煤矸石为主要原料,钢渣为辅助原料,加入适量的助熔型原料滑石和钾长石及发泡剂碳化硅制备发泡陶瓷。研究钢渣掺量(等量取代煤矸石,质量分数依次为5%、10%、15%、20%、25%、30%、35%)和助熔型原料[固定滑石和钾长石的合量为20%(w),滑石等量取代钾长石,设计掺量(w)依次为0、5%、10%、15%、20%]对发泡陶瓷物理性能、显微结构、物相组成的影响。结果表明:1)随着钢渣掺量的增加,构成骨架结构的SiO_(2)含量降低,CaO、MgO等氧化物含量上升,黏度下降,过高的钢渣掺量因SiO_(2)含量过低而不利于形成大小适中、分布均匀的气孔,钢渣掺量(w)不宜超过30%。2)滑石和钾长石助熔型原料对发泡陶瓷的影响主要是改变了原料中碱金属氧化物和构成陶瓷骨架的Al_(2)O_(3)和SiO_(2)的含量。3)发泡陶瓷的最佳配比为:m(煤矸石)∶m(钢渣)∶m(钾长石)∶m(滑石)=50∶30∶10∶10,外掺0.1%(w)的SiC。

碱激发矿渣基泡沫混凝土的制备及其封存CO_(2)可行性研究

随着工业化进程的不断推进,工业固体废弃物的排放量逐年增加,以工业固废为主要原料制备泡沫混凝土并将其用于CO_(2)封存,对实现工业固废的资源化利用和CO_(2)的经济、高效封存具有重要意义。本文以高炉矿渣为原料,选用NaOH为碱激发剂,硬脂酸钠为稳泡剂,十二烷基硫酸钠(C12H25NAO4S,SDS)为发泡剂,制备了高孔隙的泡沫混凝土。探究了不同NaOH用量对矿渣基泡沫混凝土综合性能及封存CO_(2)性能的影响。实验结果表明,随着NaOH用量的增加,泡沫混凝土的干密度逐渐增加,抗压强度先增大后减小。泡沫混凝土的内部孔隙分布不均匀,孔隙率大。SEM结果表明,当NaOH用量过高时泡沫发生破裂连通。XRD结果表明,矿渣基泡沫混凝土水化产物主要是C—S—H凝胶和Ht物相,Ht物相的层状结构使得材料的孔壁不够致密,从而影响材料的力学性能。TGA结果表明,碳化过程中水化产物有效吸收CO_(2)转化成以CaCO3为主的碳酸盐,NaOH用量12%时,CO_(2)的封存量最高为89.74 kg/m^(3)。

粉煤灰 - 锂渣基发泡陶瓷的制备及性能研究

为制备低成本兼具高孔隙率与高压缩强度的发泡陶瓷,以粉煤灰、锂渣、长石、滑石和碳化硅为原料,经1180、1200、1220、1240℃分别保温10、20、40、60 min烧结制备发泡陶瓷试样。主要研究了锂渣的掺量(质量分数分别为0、10%、20%、30%)对试样物相组成、显微结构、孔隙率及压缩强度的影响。结果表明:1)随锂渣掺量的增加,发泡陶瓷的孔隙率增加,体积密度降低,压缩强度波动;2)锂渣中丰富的钙、硫成分,可发挥助熔剂和发泡剂作用,降低烧结温度,提高发泡陶瓷的孔隙率,改善气孔圆整度,提高压缩强度;3)当锂渣掺量为20%(w)时,经1220℃保温20~40 min烧结所得发泡陶瓷的体积密度为0.32~0.40 g·cm^(-3),孔隙率为84.4%~87.6%,压缩强度为1.51~2.35 MPa。

利用电石渣替代水泥开发固碳胶凝材料

本研究利用电石渣替代部分水泥,制备新型固碳胶凝材料,研究了不同电石渣含量的胶凝材料对600 kg/m3等级泡沫混凝土的基础性能及固碳性能的影响。研究表明:电石渣的掺入导致泡沫混凝土气孔变大,28 d抗压强度先升高后降低,保温性能提高;当电石渣取代10%水泥,制备出的泡沫混凝土干密度为595 kg/m3,28 d抗压强度比未掺加电石渣的提高4.2%,达5.0 MPa;当电石渣取代50%水泥,制备出的泡沫混凝土导热系数比未掺加电石渣的降低17.1%,为1.131 W·m-1·K-1。电石渣掺加有利于改善泡沫混凝土收缩,当电石渣掺量增加,泡沫混凝土先呈现收缩减小后出现膨胀。碳化养护不仅能够固化封存CO_(2),还能提高泡沫混凝土的力学性能与保温性能。电石渣掺量越高,泡沫混凝土固碳能力越强,电石渣掺量为50%时,CO_(2)的捕获量达到46.02 wt%。

利用粉煤灰和高炉渣制备发泡陶瓷材料

这是一篇陶瓷及复合材料领域的论文。以粉煤灰和高炉渣为主要原料,外加碳化硅(SiC)为高温发泡剂,硼酸钠(Na_(2)B_(2)O_(7))为助熔剂,采用高温烧结法制备发泡陶瓷材料。主要研究了原料配比、SiC添加量及Na_(2)B_(2)O_(7)添加量对发泡陶瓷的气泡结构、体积密度、吸水率、抗压强度及导热系数的影响。实验结果表明:当粉煤灰含量为70%,高炉渣含量为30%,并额外添加0.3%SiC粉末和5%Na_(2)B_(2)O_(7),在烧成温度1100℃下保温40 min时,发泡陶瓷具有较佳的综合性能,其体积密度为0.516 g/cm^(3),吸水率为3.82%,抗压强度为3.62 MPa,导热系数为0.094 W/(m·K)。且该条件下样品的主要物相包括石英相(SiO_(2))、钙长石(CaAl_(2)Si_(2)O_(8))和辉石相(Ca(Mg,Al,Fe)Si_(2)O_(6)),大量晶体的析出促进了材料强度的提升。本研究为粉煤灰和高炉渣等工业固体废弃物转成高附加值的建筑保温材料提供一种新方法。

基于光谱学分析的硬质聚氨酯泡沫/钢渣/次磷酸铝复合材料阻燃机理研究

硬质聚氨酯泡沫(RPUF)的优异性能使其在各领域被广泛应用,但本身的易燃性为其在应用过程中埋下了巨大的安全隐患。钢渣(SS)作为提炼铁精矿后排放的固体废弃物,因其综合利用效率低下而造成一系列环境污染问题。为提高RPUF火灾安全性和钢渣的附加值,将SS和次磷酸铝(AHP)引入到RPUF中,采用一步全水发泡法,制备一系列阻燃RPUF(FR-RPUF)复合材料。利用射线荧光光谱分析(XRF)探究了SS的化学成分,并系统研究了SS/AHP对FR-RPUF复合材料的微观形貌、热稳定性、阻燃性能以及气相产物的影响。XRF测试表明:钢渣的化学成分主要是CaO、SiO_(2)、Al_(2)O_(3)、Fe_(2)O_(3)、SO_(3)、MgO,以上金属氧化物能够作为协效剂促进聚合物成炭,并覆盖在材料表面阻隔燃烧热,在凝聚相达到阻燃目的。扫描电镜(SEM)测试表明:SS/AHP与RPUF基体的相容性较差导致FR-RPUF的泡孔出现不同程度的破损。阻燃测试表明:RPUF-1、RPUF-4、RPUF-5的极限氧指数分别为24.2 vol%、23.4 vol%、19.7 vol%,说明SS和AHP存在一定的协效阻燃作用,且RPUF/SS/AHP复合材料全部通过UL-94 V-0级别,满足外墙保温材料使用要求。热重-红外分析(TG-FTIR)测试表明:SS/AHP并未改变RPUF的降解过程,气相产物主要为碳氢化合物、羰基化合物、氨基甲酸酯、CO_(2)、异氰酸酯化合物、芳香族化合物、氰化氢、羰基化合物和酯类。对典型挥发性产物进一步分析发现,AHP和SS的加入促进RPUF基体早期降解。拉曼测试表明:当SS/AHP加入到RPUF后,RPUF-4的D峰与G峰的峰面积比(I_(D)/I_(G))值最小,表明SS/AHP的加入提高了FR-RPUF复合材料炭渣的致密性、石墨化程度。结合上述分析提出阻燃机理:首先AHP吸热分解,降低了火焰周围的温度,其分解的PO·自由基捕获游离的HO·抑制连锁反应,分解产生的焦磷酸铝与炭渣覆盖在基体表面,抑制了火焰和可燃气体的扩散。AHP分解产生的PH3遇氧气生成酸性物质(磷酸和聚磷酸),促进了RPUF脱水成炭,并且钢渣中的矿物成分会与磷酸或聚磷酸反应,形成致密炭层,与AHP共同发挥协效阻燃作用。研究为SS和AHP复配阻燃硬质聚氨酯泡沫材料提供理论依据和实验基础。

预养护与碳化时间对泡沫混凝土碳化效果的影响及分析

碳矿化技术是封存CO_(2)、解决温室效应问题最直接有效的技术之一。不锈钢渣的主要成分为γ-硅酸二钙(γ-C_(2)S),是一种极具碳化潜力的材料。本研究以质量分数为80%的不锈钢渣和矿粉为主要原料,制备等级为A12干密度的泡沫混凝土,在0.4 MPa、60℃的碳化环境下研究预养护时间和碳化时间对泡沫混凝土抗压强度和固碳率的影响。结果表明,最佳的预养护时间为2 d,预养护1和2 d的泡沫混凝土抗压强度均在碳化3 d后达到峰值,预养护2 d的泡沫混凝土抗压强度比预养护1 d的泡沫混凝土抗压强度提升了51.19%。碳化3 d时,预养护1和2 d的泡沫混凝土固碳率分别为9.94%和12.10%。本研究在简易的碳化环境下,利用工业固废实现碳矿化过程,既大量消纳固废,又封存二氧化碳,具有重要的意义。

钢渣细骨料泡沫混凝土制备及抗压强度计算

为实现钢渣资源化利用,以钢渣作为细骨料,采用不同钢渣粒径、钢渣取代量和水胶比制备了钢渣泡沫混凝土试块,通过7 d无侧限抗压强度确定出最优配合比为1.18 mm钢渣粒径、20%(与水泥质量比,下同)钢渣取代量、0.45水胶比。根据分形理论建立了最优配合比下钢渣泡沫混凝土抗压强度与孔隙率的关系式,试样的分形维数D可由盒计数法算出。此分形模型计算的抗压强度预测值与试验值吻合度较高。通过对比其他文献中泡沫混凝土抗压强度的实测值,证明了分形计算模型能够准确预测出泡沫混凝土的抗压强度,具有良好的应用前景。

烧成制度对制备煤矸石发泡陶瓷性能的影响

为实现固体废弃物高附加值资源化利用,在确定配方m(煤矸石)∶m(钢渣)∶m(钾长石)∶m(滑石)=50∶30∶10∶10,及外掺0.1%SiC的基础上,研究烧成制度对发泡陶瓷物相组成、表观形貌、物理性能及微观形貌的影响。结果表明:烧成温度影响高温时的液相量,从而对发泡陶瓷的气孔结构和物理性能造成影响;升温速率影响高温时液相生成的速率;保温时间影响高温时的液相量和气体量。以2℃/min的升温速率从1150℃(液相出现)烧至1170℃后保温60 min,在此烧成制度下,液相生成速率与SiC分解速率相匹配,制备的发泡陶瓷性能最佳,此时试样的体积密度0.53 g/cm^(3),抗弯强度5.32 MPa,吸水率6.43%,总气孔率77.92%,闭气孔率74.51%。

小颗粒石灰石与石灰化渣脱磷效果试验研究

为了探究转炉喷吹小颗粒石灰石炼钢的可行性,基于化渣脱磷基础试验,对比了小颗粒石灰石与石灰在相同条件下的化渣脱磷效果,并从造渣脱磷机理上进行分析。研究表明:小颗粒石灰石在熔池内分解形成高活性石灰,可同时实现在熔池内部及界面的脱磷反应,脱磷效果与石灰相当,终点铁水脱磷率均可以达到85%以上;小颗粒石灰石比石灰的前期脱磷速率快,可以在更短的时间内将大部分磷元素脱除;小颗粒石灰石与石灰均可以实现均匀化渣,石灰石化渣渣层较高,泡沫渣更为明显,渣中元素分布均匀,磷元素主要富集在Ca_(3)(PO_(4))_(2)固溶体相中。

一种再生复合相变材料泡沫玻璃的制备与性能测试

为减少建筑材料能耗,试验通过固废物水淬渣和陶瓷废料,结合氧化铝和硼砂,制备一种泡沫玻璃材料,并研究其强度和保温性能。结果表明,该泡沫玻璃材料的最佳配方为:在900℃发泡温度条件下,水淬渣、陶瓷废料和纯碱份数比例固定为40∶60∶10,氧化铝和硼砂添加量分别是4%、8%。此时,制备的泡沫玻璃材料抗压强度为9.38 MPa,导热系数为0.411 W/(m·K),均符合建筑保温材料要求。综上,试验中的泡沫玻璃材料有着良好的强度和保温性能,是一种绿色环保的建筑节能材料,可以适用于建筑外墙等。