Resource utilization of slag from desulphurization and slag skimming:A comprehensive recycling process of all components

In order to make the slag from desulphurization and slag skimming(SDSS)to be comprehensively recycled and utilized,a combined process of beneficiation and building materials preparation was proposed to recover iron from SDSS,meanwhile to apply the remaining slag tailings as cement admixture.From this process,three iron-rich products were recovered in stages by clean gravity-magnetic separation,slag tailings were left.Slag powder was prepared by ultrafine grinding of slag tailings.The stability,setting time and cement mortar strength of the slag tailings cements(STC)which were mixed with Portland cement and slag powder were studied respectively.The results showed that a proper overall performance still could be obtained at the slag powder content of 30%.Chemical composition analysis,X-ray diffraction(XRD)analysis,metallographic microscope and scanning electron microscope(SEM)analysis were employed to assess the characteristics of the SDSS and the products obtained from the whole process.The results indicated that the three iron-rich products could be used as a raw material for steelmaking and ironmaking and the relatively large amount of calcium silicate(C_(2)S)and tricalcium silicate(C_(3)S)in the slag tailings make the addition of slag powder into the Portland cement feasible.

KINETICS OF DESULPHURIZATION IN PERMANENT CONTACT OF SLAG AND STEEL

The curve of % S vs reaction time is described quantitatively based on the electrochemical model directly deduced from the principle of electrochemistry as well as the given method for calculating the initial oxygen potential along slag/steel interface.The calculated data is in good agreement with the experimental results. During desulphurization,both L_s~* and L_s,the sulphur partition along the interface and that in the bulk,go up in association with the descending of oxygen potential along interface. The plot of L_s~* against reaction time follows a parabolic curve,while that of L_s is of hyperbola type.Correspondingly,on curves of driving force parameter vs reaction tone,either calculated or experimental,a hump occurs.

Adsorption of Pb^2+and Cu^2+with Unburned Desulphurization Slag Modified Nickel Slag

Desulphurization slag modified nickel slag adsorbent was prepared by unburned forming technology. The structure of the sample was characterized by BET,XRD,IR,SEM and EDAX. The adsorption performance of Pb^2＋ and Cu^2＋ onto the resultant adsorbent from aqueous solution was studied. Results indicated that the adsorbent possesses a network pore structure formed by the AFt and C–S–H through cross lapping; the adsorbent contains a large number of Si–OH and Al–OH functional groups. The presence of functional groups not only provides abundant adsorption sites for Pb^2＋ and Cu^2＋,but also improves the adsorption performance of Pb^2＋ and Cu^2＋ from waste water through the complexation of heavy metal ions. The result of specific surface area analysis showed that the adsorbent sample possesses mesoporous structure and the BET specific surface area is 27.15 m^2/g. The solution p H values for the adsorption of Pb^2＋ and Cu^2＋ were optimized to be 6 and 5.5,respectively. The adsorption capacities of Pb^2＋ and Cu^2＋ gradually increase,whereas the removal rates of the two metal ions decrease with increasing the initial concentration of simulated solution. The resultant adsorbent gives a higher adsorption capacity for Cu^2＋ than for Pb^2＋ in the single ion solution. However,it shows preferential adsorption of Pb^2＋ rather than that of Cu^2＋. Meanwhile,results of recyclability indicate the remarkable regeneration capacity,re-adsorption ability and reusability performance of the adsorbent sample.

The Ionization Theory of Desulphurization of the Panzhihua Blast Furnace Slag

With the proper choice of the ion species present in the Panzhihua blast furnace slag, the sulphur partition ratio was calculated based on the ionization theory of the slag. It can be concluded that TiO_2 reacts as an acidtc oxide and the Panzhihua ore or concentrate cannot be treated as a semi-self-fluxing ore.

Vacuum Treatment for Simultaneous Desulphurization and Dephosphorization of Hot Metal and Molten Steel

The vacuum treatment for simultaneous desulphurization and dephosphorization of hot metal and molten steel with pre-melted CaO-based slag was carried out.For pre-treatment of hot metal,both desulphurization and dephosphorization are improved with the increase of CaO in slag,but deteriorated with the increase of CaF2 in slag.The average desulphurization and dephosphorization rate is 68.83 % and 78.46 %,respectively.For molten steel,the substitution of BaO for CaO in slag has minor effect on simultaneous desulphurization and dephosphorization.The desulphurization and dephosphorization rate is higher than 90% and 50% respectively with the lowest final sulfur and phosphorus mass percent being 0.001 2% and 0.010%,respectively.The overall effect of simultaneous desulphurization and dephosphorization of molten steel is better than that of hot metal.

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.

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.

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.

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%.

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.

Experimental Research on Refining Slag Systems Containing BaO for Ultra-Low Sulphur Steel

The experimental research on refining slag systems for ultra-low sulphur steel was carried out in a 10 kg induction furnace.It was proved that sulphur element in molten steel can be removed to less than 5×10^(-6) by adding CaO-Al_2O_3-SiO_2-MgO-CaF_2 slag on the surface of molten steel and feeding CaO-BaO-CaF2 wire into molten steel.And L_s,which is the coefficient of sulphur between slag and molten steel,that is ω(s)/ω[s],increases by increasing I(I = ωBaO/ωCaO).When I=5/3,L_s can be up to its maximum of 633.The CaSi is effective for deep desulphurization,especially when it is added to the slag of wire feeding.

Recovery of bismuth and antimony metals from pressure-leaching slag

The leaching behavior of metals from a pressure-leaching slag was investigated using a desulphurization-leaching-hydrolysis process for the recovery of bismuth and antimony.Various parameters were studied,including the amount of acid added,temperature,time,addition of NaCl and solid-liquid ratio in the leaching process.The experimental results show that the contents of bismuth and antimony are mostly enriched in the process of kerosene desulphurization.More than 98% Sb and 96% Bi are extracted under the determined conditions.In the process of hydrolysis,the precipitation rates of bismuth and antimony are 97.80% and 94.59%,respectively.Under the optimum experimental conditions,the recovery rate of bismuth and antimony can be up to 95.80% and 90.80%,respectively.

Wettability of Molten Steel/Na2O-Li2O-SiO2-B2O3 Slag System

The vacuum treatment for simultaneous desulphurization and dephosphorization of hot metal and molten steel with pre melted CaO based slag was carried out. For pre treatment of hot metal, both desulphurization and dephosphorization are improved with the increase of CaO in slag, but deteriorated with the increase of CaF 2 in slag. The average desulphurization and dephosphorization rate is 68 83 % and 78 46 %, respectively. For molten steel, the substitution of BaO for CaO in slag has minor effect on simultaneous desulphurization and dephosphorization. The desulphurization and dephosphorization rate is higher than 90 % and 50 % respectively with the lowest final sulfur and phosphorus mass percent being 0 001 2 % and 0 010 %, respectively. The overall effect of simultaneous desulphurization and dephosphorization of molten steel is better than that of hot metal.

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 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.

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.

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。

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。