Crystallization characteristics of iron-rich glass ceramics prepared from nickel slag and blast furnace slag

The crystallization process of iron-rich glass-ceramics prepared from the mixture of nickel slag（NS） and blast furnace slag（BFS） with a small amount of quartz sand was investigated.A modified melting method which was more energy-saving than the traditional methods was used to control the crystallization process.The results show that the iron-rich system has much lower melting temperature,glass transition temperature（Tg）,and glass crystallization temperature（Tc）,which can result in a further energy-saving process.The results also show that the system has a quick but controllable crystallization process with its peak crystallization temperature at 918°C.The crystallization of augite crystals begins from the edge of the sample and invades into the whole sample.The crystallization process can be completed in a few minutes.A distinct boundary between the crystallized part and the non-crystallized part exists during the process.In the non-crystallized part showing a black colour,some sphere-shaped augite crystals already exist in the glass matrix before samples are heated to Tc.In the crystallized part showing a khaki colour,a compact structure is formed by augite crystals.

Effect of Fe_2O_3 on the crystallization behavior of glass-ceramics produced from naturally cooled yellow phosphorus furnace slag

CaO–Al2O3–SiO2(CAS) glass-ceramics were prepared via a melting method using naturally cooled yellow phosphorus furnace slag as the main raw material. The effects of the addition of Fe2O3on the crystallization behavior and properties of the prepared glass-ceramics were studied by differential thermal analysis, X-ray diffraction, and scanning electron microscopy. The crystallization activation energy was calculated using the modified Johnson–Mehl–Avrami equation. The results show that the intrinsic nucleating agent in the yellow phosphorus furnace slag could effectively promote the crystallization of CAS. The crystallization activation energy first increased and then decreased with increasing amount of added Fe2O3. At 4wt% of added Fe2O3, the crystallization activation energy reached a maximum of 676.374 kJ·mol−1. The type of the main crystalline phase did not change with the amount of added Fe2O3. The primary and secondary crystalline phases were identified as wollastonite (CaSiO3) and hedenbergite (CaFe(Si2O6)), respectively. © 2017, University of Science and Technology Beijing and Springer-Verlag Berlin Heidelberg.

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℃.

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.

A novel process of preparing glass-ceramics directly from molten steel slag

A novel process technology to prepare glass-ceramics directly from molten steel slag （MSS） is proposed in the study. The liquid-solid mixing method was used to adjust the components of the MSS and glass-ceramics was obtained. The effects of heat-treatment conditions on the microstructure ,physical and mechanical properties of samples were studied. Economical benefits of the novel process were analyzed. The results show that heat-treatment is a very effective approach to achieving crystallization. The dominant crystal phase in products is diopside [ （ Mg6Al2Fe2 ） Ca （ Si1.5 Al5 ） O2 ]. The shape of the crystallization is like a granule. The glass-ceramic samples exhibited good mechanical properties and presented chemical stability. The economic benefits of the process are remarkable due to less energy consumption compared with conventional glass-ceramics production methods.

Experimental study on glass-ceramics preparation from hot steel slag

When liquid steel slag produced from steelmaking process was treated into the post-cold slag by conventional methods,the great deal of slag heat was dissipated into the environment,causing a lot of energy waste and environmental pollution.In this study,a novel approach of direct utilization of hot steel slag as a raw material and slag heat for the production of glass-ceramics was proposed and experimentally tested.In order to simulate liquid slag from steelmaking electric furnace,40%water-quenched slag was remelted at 1 450℃and then mixed with 60%melting additives(silica powder,alumina powder and sodium oxide, etc.)and subsequently melted together at 1 500℃for 1 h into modified liquid slag which was cast,heat-treated, annealed and transformed into glass-ceramics.The heat-treated glass samples were investigated using differential thermal analysis(DTA),X-ray diffraction(XRD),and scanning electron microscopy(SEM). The results show that dominant crystalline phase is diopside[CaFe(SiO_3)_2]and the shape of the crystal is like the granule,diameter is about 0.2 -0.6μm.A glass-ceramic with nucleation temperature of 695℃for two hours and crystallization temperature of 893℃for one hour and 1 163℃for half-hour exhibited the best combination of properties.This method of slag mixed with melting additives to adjust the composition of the parent glass is important for the industrial production of glass-ceramics by direct utilization of hot steel slag.

Development of Glass Ceramics Made From Ferrous Tailings and Slag in China

A great amount of ferrous tailings and slag cause severe damage to the ecological environment, which must be reclaimed and utilized. The composition, type, and characteristics of ferrous tailings and slag in China were introduced. The research status and the application outlook of glass ceramics made from ferrous tailings and slag were discussed. Glass ceramics made from ferrous tailings and slag can be applied to various fields, and it will be environmentally conscious materials in the 21st century.

Influence of Crucible Material on the Microstructure and Properties of Iron Rich Glass-Ceramics

Slag glass melting is usually performed on a laboratory scale in crucibles, which are economically viable tools for the production of slag glass-ceramics. In this work, quaternary CaO-Al2O3-MgO-SiO2（CAMS） glass-ceramics were prepared by melting the tailing of Bayan Obo mine tailing, blast furnace slag, and fly ash in alumina and graphite crucibles. The effect of the crucible material on the microstructure and properties of the glass-ceramics was investigated using differential scanning calorimetry, X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy and inductively coupled plasma atomic emission spectroscopy. Results indicated that the contents of Al2O3 and Fe2O3 in the initial glass were significantly changed by the corrosion of the alumina crucibles during the glass melting process and by the reducing action of the graphite crucibles. The main crystal phases of glass-ceramics melted in alumina crucibles and graphite crucibles were Ca（Mg, Fe, Al）（Si, Al）2O6, coesite and Ca（Mg, Al）（Si, Al）2O6, respectively. According to these findings, we conclude that the microstructure and properties of the glass-ceramics are affected by the crucibles.

Effects of sintering atmosphere on the physical and mechanical properties of modified BOF slag glass

This study proposes an efficient way to utilize all the chemical components of the basic oxygen fttrnace （BOF） slag to prepare high value-added glass-ceramics. A molten modified BOF slag was converted from the melting BOF slag by reducing it and separating out iron component in it, and the modified BOF slag was then quenched in water to form glasses with different basicities. The glasses were subsequently sintered in the temperature range of 600-1000℃ in air or nitrogen atmosphere for 1 h. The effects of different atmospheres on the physical and mechanical properties of sintered samples were studied by using differential scanning calorimetry （DSC）, X-ray diffraction （XRD） and scanning electron microscopy （SEM） and by conducting experiment on evaluating the sintering shrinkage, water absorption and bulk density. It is found that the kinetics of the sintering process is significantly affected by sintering atmosphere. In particular, compared with sintering in air atmosphere, sintering in N2 atmosphere promotes the synergistic growth of pyroxene and melilite crystalline phases, which can contribute to better mechanical properties and denser microstructure.

锂渣-废玻璃基多孔陶瓷的制备及性能研究

为有效利用锂渣和废玻璃这两种典型的工业固废和城市固废,以锂渣和废玻璃为原料,采用发泡法制备多孔陶瓷,并对其制备过程和性能进行了研究。通过调控锂渣与废玻璃的配比、烧结温度和烧结时间等参数,探究了各因素对多孔陶瓷孔隙率、体积密度、吸水率和抗压强度等性能的影响。结果表明,适当添加锂渣能够在高温下促进熔渣液相中形成少量的硅酸盐固相,从而强化陶瓷骨架的形成,改善陶瓷孔隙结构和抗压强度。然而,过量的锂渣会抑制多孔陶瓷的发泡过程。以30%锂渣和70%废玻璃为原料,在烧结温度990℃和烧结时间30 min的条件下,制备出的多孔陶瓷孔隙率为41.91%,抗压强度为7.26 MPa,体积密度为1.34 g/cm^(3),吸水率为5.85%。本研究利用工业和城市废弃物制备性能优异的多孔陶瓷,为锂渣的资源化利用提供了一定的参考,具有良好的环境和经济效益。

Crystallization mechanism of glass-ceramics prepared from stainless steel slag

Glass-ceramics have been prepared by using stainless steel slag, fly ash and coal fly ash that were figobtained from industrial solid waste. The crystallization behavior and mechanical characterization of the glass-ce-ramics with different （CaO ＋ MgO）/（SiO2 ＋ Al2O3） content ratios were studied. While the basicity decreases from 1.2 to 0.9 cm^-3, the bridge oxygen content increases from 1.18 ~ 10^21 to 1.34 ~ 10^21 cm^-3. According to the deconvolution of Raman spectra, the relative abundance of the stretching of Si-Onb bond （Q^n units） can be obtained. The increase in the Q^3 units dominates the polymerization in the process of decreasing basicity. This change in bonding is demonstrated to lead to polymerization of the glass network and the increase in crystallization activation energy from 336.0 to 360.7 kJ·mol^-l. The results demonstrate that the production of the glass-ceramics from industrial steel slag, fly ash and coal fly ash is cost-effective and offers advantages over other production methods.

熔制坩埚对CaO-Al_2O_3-MgO-SiO_2系矿渣微晶玻璃结构与性能的影响

以白云鄂博二次选后尾矿、高炉渣和粉煤灰为主要原料,采用熔融法分别在氧化铝坩埚和石墨坩埚熔制制得Ca O-Al_2O_3-Mg O-Si O_2(CAMS)系微晶玻璃,利用DSC、XRD、SEM、EDS、ICAP、XPS等测试手段,研究了不同坩埚熔制对微晶玻璃成分、显微结构及性能的影响。研究表明:高温玻璃熔液对氧化铝坩埚的侵蚀作用及石墨坩埚的还原作用,使基础玻璃中Al_2O_3和Fe2O3含量发生较大变化,氧化铝坩埚熔制制备的基础玻璃有一个析晶峰,温度为905℃,对应的微晶玻璃主晶相为含铁透辉石Ca(Mg,Al)(Si,Al)_2O_6,而石墨坩埚熔制制备的基础玻璃出现两个析晶峰,温度分别为866℃和805℃,对应的微晶玻璃主晶相透辉石Ca(Mg,Al)(Si,Al)2O6和次晶相柯石英Si O_2,由于以上原因导致制备的微晶玻璃在显微结构及理化性能上也存在一定的差异。

金渣-钢渣-钛渣微晶玻璃的析晶动力学研究

采用差热分析(DTA)的方法研究了金渣-钢渣-钛渣复合微晶玻璃的析晶动力学,利用Ozawa和Kissinger方法分别计算了析晶活化能E和晶体生长指数n,分析了金渣-钢渣-钛渣复合微晶玻璃的析晶机理。结果表明:随着金渣添加量的增加,析晶活化能E逐渐降低,晶体生长指数n逐渐增大。当金渣的添加量为55%时,析晶活化能均最低,晶体生长指数最大:利用Ozawa方法计算得到的析晶活化能E=309 KJ/mol,对应的晶体生长指数n=6.31;利用Kissinger方法计算得到的析晶活化能E=290 KJ/mol,对应的晶体生长指数n=6.72。

TiO_2对黄磷炉渣-滇池底泥微晶玻璃析晶的影响

利用自然冷却黄磷炉渣和滇池底泥为原料协同制备微晶玻璃。借助差热分析(DTA)、X射线衍射仪(XRD)、扫描电子显微镜(SEM)研究晶核剂TiO_2对微晶玻璃析晶行为的影响。结果表明:随着TiO_2添加量的增加,基础玻璃的析晶活化能E逐渐增加,析晶效果逐渐变差; TiO_2的添加不改变微晶玻璃的晶相类型,其晶相均为镁黄长石(Ca2MgSi2O7)和钙黄长石(Ca2Al2Si O7);原料本身含有的TiO_2就能促进黄磷炉渣-滇池底泥基础玻璃整体析晶,析晶活化能最小且性能最优。

碳酸钙对磷渣-煤矸石烧结多孔微晶玻璃结构和性能的影响

多孔微晶玻璃具有导热系数低、力学性能好、抗腐蚀性强等优点,是一种隔热、吸声的轻质功能材料。为拓展多孔微晶玻璃的制备原料范围,同时大宗量、高附加值利用工业废渣-磷渣和煤矸石。本文以磷渣和煤矸石为原料,采用烧结法制备多孔微晶玻璃。利用X射线衍射、扫描电子显微镜及阿基米德法,对制备的试样进行表征,研究发泡剂碳酸钙掺量对体系析晶、发泡和宏观性能的影响。研究表明,碳酸钙掺量不影响体系析晶相的种类,但体系析晶度随碳酸钙掺量增加先增大后减小;碳酸钙掺量为2%~6%(质量分数)时,增大掺量,利于发泡。体系中气孔孔径增大且趋于均匀,试样孔隙率增大,体积密度降低。但随着掺量进一步增大,体系发泡效果降低。当碳酸钙掺量为4%~8%(质量分数)时,可获得体积密度为0.86~0.92 g/cm^(3),孔隙率为60.7%~70.3%,抗压强度为7.89~15.11 MPa,性能较优的硅灰石多孔微晶玻璃。本研究以工业废渣为原料,降低了多孔微晶玻璃的制备成本,同时为工业废渣利用提供一种途径借鉴,具有深远的资源和环保意义。

利用复合工业废渣制备CaO-MgO-Al_2O_3-SiO_2微晶玻璃

以镍渣和粉煤灰为主要原料采用熔融法制备微晶玻璃。利用正交设计方法确定工业废渣复合微晶玻璃的最佳原料配比:镍渣34%、粉煤灰28%、钙盐18%、钠盐4%、形核剂TiO2+ZnO(适量)、还原剂11%。通过XRD、SEM分析技术、物理化学性能测试等手段确定微晶玻璃的主晶相、微观结构及性能特征。结果表明,在最佳条件下制备的微晶玻璃主晶相为细小均匀的块状辉石,弯曲强度为58.2MPa,显微硬度为842HV,体积密度为2.87g/cm3,吸水率为0.02%,耐酸性0.02%,耐碱性0.18%,光泽度89光泽单位。

Na_2O-CaO-SiO_2-MgO-Al_2O_3-ZnO微晶玻璃制备及晶化行为的研究

本文设计了Na2O-CaO-SiO2-MgO-Al2O3-ZnO体系,采用熔融法制备了以磷渣为主要原料的微晶玻璃,磷渣在微晶玻璃中的使用率达到67～75%,并利用XRD,SEM等确定了玻璃的最佳热处理制度,研究了Na2O对微晶玻璃析晶及特征的影响。结果发现经过750℃核化4h,850℃晶化2h,得到主晶相为硅灰石(CaSiO3)和菱硅钙钠石(Na2Ca2Si3O9)的微晶玻璃。玻璃中表面析晶和整体析晶同时存在,其中Na2O可促进整体析晶和菱硅钙钠石的析出。

晶核剂P_2O_5对CaO-Al_2O_3-SiO_2系黄磷炉渣微晶玻璃析晶的影响

采用熔融法以自然冷却黄磷炉渣为主要原料,P_2O_5为晶核剂,制备了黄磷炉渣微晶玻璃。利用X射线衍射仪(XRD)、差热分析(DTA)和扫描电子显微镜(SEM)等分析技术手段,探究了晶核剂P_2O_5(以KH_2PO_4的形式引入)对黄磷炉渣微晶玻璃晶化行为及物化性能的影响规律。结果表明:黄磷炉渣基础玻璃的析晶峰温度Tp及析晶活化能E随着P_2O_5晶核剂的增加呈现先减小后增大的趋势;当晶核剂P_2O_5加入量达到4wt%时,黄磷炉渣基础玻璃的析晶峰温度Tp及析晶活化能E最小,析晶效果最优,物化性能最优;主晶相硅灰石(CaSiO_3)并不随着晶核剂P_2O_5加入量的增大而发生改变,同时能够促进晶相氟磷灰石(Ca_5(PO_4)_3F)生成。

铜渣碳热还原-熔融尾渣制备微晶玻璃的综合性实验

文章根据火法炼铜过程产生的铜渣中含铁品位高、碳热还原后尾渣成分与硅酸盐微晶玻璃化学成分相近等特点,设计了铜渣碳热还原提铁-熔融尾渣制备微晶玻璃实验。该实验对铜渣中铁的回收率达98.93%,并获得了综合性能较好的微晶玻璃。实验过程包括铜渣成分调整、碳热还原、渣金分离、尾渣物相表征、微晶玻璃制备、微晶玻璃性能检测等多个环节,涉及冶金学、矿物学、材料学等多个学科领域的基础理论,能够增强学生的科研兴趣,提高科研素养、实践能力和创新意识。