A review on nut coke utilisation in the ironmaking blast furnaces

In the ironmaking blast furnaces, nut coke (10–40 mm; 2–23?wt-%) is charged together with the ferrous burden. A systematic review is performed to understand the effects of nut coke use on the permeability, thermal reserve zone (TRZ), reduction kinetics and softening &; melting behaviour. State of the art techniques for enhancing reactivity and to lower TRZ temperature are discussed. To utilise nut coke effectively, need of correlational research is expressed on its behaviour with different burden chemistry, carbon ordering, ash content and distribution style. Challenges for higher nut coke utilisation like decrease in regular coke layer thickness and unconsumed fines in lower part of the furnace are pointed out. The scope of further research is marked via this review.

This review was submitted as part of the 2016 Materials Literature Review Prize of the Institute of Materials, Minerals and Mining run by the Editorial Board of MST. Sponsorship of the prize by TWI Ltd is gratefully acknowledged     

CATIONIC SURFMERS WITH BENZYL GROUPS:SYNTHESIS AND COPOLYMERIZATION WITH ACRYLAMIDE

A series of cationic surfmers with benzyl groups (QARBCs) with different R groups on the benzene ring were synthesized and characterized by IR,<'1>H-NMR,<'13>C-NMR. The aggregation of QARBCs was studied by the steady-state fluorescence technique. It tumed out that QARBCs had surface activity and their cntical micelle concentration (CMC) values varied in the range of 10<'-2>-10<'-3> moI/L with slight increase with temperature. The copolymerization of acrylamide (M<,1>) and QARBCs(M<,2>) was studied below and above CMC,their reactivity ratios were determined by the Finemann-Ross method. It was found that below CMC,copolymerization took place in a homogeneous system and reactivity ratios of acrylamide and QARBCs were less than l;while above CMC,reactivity ratios of QARBCs were greater than l. The copolymerization mechanism of QARBC was observed to be similar to that of micellar polymerization. QARBCs tended to homopolymerization,which gave rise to micro-blocky sequences in the polymer backbone. The Q and e values of QARBCs were calculated according to the Alfrey-Price equation by using r<,1(AM)> and r<,2(QARBO).> Samples of poly(AM-co-QARBC) were prepared above and below CMC and their hydrophobic associations were studied by the steady-state fluorescence spectra and 2D NOESY spectra,and their critical associating concentrations (CAC) were estimated. The results showed that samples of poly(AM-co-QARBC) prepared above CMC had stronger hydrophobic association in aqueous solution than those prepared below CMC.     

丙烯酰胺与丙烯酸钠水溶液辐射共聚合竞聚率的研究

本文研究了丙烯酰胺(AM)与丙烯酸钠(AANa)水溶液辐射共聚合在室温下不同pH值的竞聚率。聚合物的转化率高于10％,因此用Mayo-Lewis积分公式计算,得到的r_1(AM)和r_2(AANa)分别为0.90～1.18及0.32～0.48,不同的几种条件下,并无明显区别。     

焦炭强度与热性质控制因素分析

在20kg小焦记上进行了11种单种煤和8种配煤方案的炼焦试验,建立了焦炭质量预测模型。结果表明,单一的煤质指标与焦炭强度的关系不明显,多因素指标进行焦炭质量的预测效果较好;焦炭反应性与单一煤质指标中Vd、^—Rmax^0、Ad之间有较好的关系,且随反应温度的升高而增大。     

Investigation of the void reactivity effect in large-size Lead Fast Reactors

An aspect of great relevance in Lead Fast Reactors (LFRs) is the actual void reactivity evaluation. The purpose of this work is double: to inquire into the physical problem, and to evaluate the impact of different approaches and numerical methods on the calculation of the critical reactor parameters involved. Thus, results concerning void effect contributors have been evaluated through a cross-checked analysis performed by means of both a deterministic and a stochastic code. The field of investigation that has been assumed consists in the reference configuration of the 600 MW_e European Lead-cooled SYstem (ELSY), under development within the 6th and 7th EURATOM Framework Programmes. Calculations have been carried out on a 1500 MW_th MOX-fuelled core, composed by wrapper-less square Fuel Assemblies (FAs) with pins on a square lattice. The ERANOS (European Reactor Analysis Optimized System) deterministic code ver. 2.1 and the MCNP Monte Carlo code ver. 4c have been employed in conjunction with the JEFF-3.1 nuclear data library to assess the void reactivity variation and its breakdown into the most relevant nuclides, using both the neutron balance equation method and perturbation theory. Results have shown a very good agreement between ERANOS and MCNP outcomes: the huge reactivity worth determined by the core active region voiding (approximately 5000 pcm) is due to the predominant contributions of even isotopes – among which ²³⁸U plays a major role, being responsible for roughly 4300 pcm – as a consequence of their fission cross-section high sensitivity to spectral hardening (threshold reactions), despite their modest contribution to the total fissions.     

Development of a dispersion process for carbon nanotubes in ceramic matrix by heterocoagulation

The surface properties of carbon nanotubes have been changed by heat treatment with ammonia to yield a basic surface or with N₂ to yield an acidic surface without destroying the integrity of the nanotubes. The dispersion state of CNTs could be much improved by the adsorption of a cationic dispersant of poly(ethylenimine) (PEI) or an ionic dispersant of sodium dodecyl sulfate (SDS). Through the electrostatic interaction between components, CNTs could be successfully coated with particles of titania or alumina by colloidal heterocoagulation. A titania coating on 1.5wt% CNTs, shows the same photocatalytic properties in phenol degradation and has advantages in separation and reuse.     

Improvement of the reduction capacity of activated carbon fiber

The reduction property of activated carbon fibers (ACFs) enables them to be used in the recovery of noble metals from wastewater, or in the extraction of gold or silver from ore leaching solutions. In order to effectively recover or extract noble metals, it is important to enhance the reduction capacity of ACFs and to improve the particle size of the noble metal reduced and adsorbed on the surface of activated carbon fibers. In this paper, the effect of the preparation method and surface modification of ACFs on their reduction capacity was studied. The results show that the preparation methods of ACFs have significant influence on their reduction-adsorption capacities for silver ions in solution—those ACFs prepared with phosphoric acid or zinc chloride activation have much higher reduction capacities. Moreover, surface modification of ACFs with some inorganic oxidants such as nitric acid, potassium permanganate, or hydrogen peroxide, though resulting in a small decrease of specific surface area or pore volume, will enhance the reduction capacity of oxidized ACFs for silver ions. Furthermore, methylene blue, aniline, or p-nitrophenol present in solution or adsorbed on ACFs can also significantly increase the reduction capacities of sisal-based ACFs for silver ions.     

Catalytic gasification of coal using eutectic salts: identification of eutectics

Different eutectic salt mixture catalysts for the gasification of Illinois No. 6 coal were identified and various impregnation or catalyst addition methods to improve catalyst dispersion were evaluated in this study. In addition, the effects of major process variables such as temperature, pressure, and steam/carbon ratio were investigated in a thermogravimetric analyzer (TGA) and fixed-bed bench scale reactor systems. The TGA studies showed that the eutectic catalysts increased CO₂ gasification rate significantly. The methods of catalyst preparation and addition had significant effect on the catalytic activity and coal gasification. Based on the TGA studies of several eutectic systems, the 43.5% Li₂CO₃-31.5% Na₂CO₃-25% K₂CO₃ and 39% Li₂CO₃-38.5% Na₂CO₃-22.5% Rb₂CO₃ ternary eutectics, the 29% Na₂CO₃-71% K₂CO₃ binary eutectic and the K₂CO₃ single salt catalysts were selected for the fixed-bed studies. The catalyst loading increased the gasification rate and almost complete conversion of carbon was observed when 10 wt.% of catalyst was added to the coal. Upon further increasing the catalyst amount to 20 wt.% and above, there was no significant rise in gasification rate.     

Structure and reactivity of silica-supported 12-tungstophosphoric acid

The structure and reactivity of silica-supported 12-tungstophosphoric acid (HPW) with 10–60 wt.% loading prepared by the impregnation method are studied by using chemical analysis, X-ray diffraction (XRD), FT-IR, FT-Raman, TG, ³¹P MAS NMR, surface area measurement and microreactor tests. It is found that most of HPW in samples is well dispersed on the support, and may mainly exist as small crystalline particles with an average size around 24.3–27.6 nm, calculated by XRD results. Based on various characterization techniques, it may be concluded that silica-supported HPW still keeps its Keggin structure. The effect of different loading on the reactivity of silica-supported HPW without promoter or promoted by Pt/Al₂O₃ is studied by using isomerization of n-hexane as a probe reaction, and the reactivity is found to be strongly loading related.     

Catalytic oxidation of carbon/carbon composite materials in the presence of potassium and calcium acetates

The catalytic effects of potassium acetate (KAC) and calcium acetate (CaAC) on the oxidation of carbon/carbon composites (C/C composites) used in aircraft brake system have been characterized. Potassium exhibited a very strong catalytic effect on the oxidation of the selected carbon samples, including C/C composite blocks impregnated with aqueous KAC solution and graphite powder physically mixed with KAC powder. The initial amount of catalyst loading and the pre-treatment in inert gas were found to affect its catalytic effectiveness. Impregnated calcium was also a good catalyst for the oxidation of C/C composites, but its effectiveness is much lower than that of potassium and is much less sensitive to catalyst loading amount and pre-treatment. Calcium acetate physically mixed with graphite powder only showed a slight catalytic effect. The experimental results suggested that the interfacial contact between catalyst and carbon is the key factor determining catalytic effectiveness, in agreement with previous studies using porous carbon materials. Due to its unique wetting ability and mobility on the carbon surface, potassium can form and maintain such contact with carbon and is, therefore, more effective in the C-O₂ reaction than calcium. The formation and development of such contact, which can also be affected by catalyst loading and pre-treatment process, can explain well the influence of these experimental conditions on the catalytic effect of potassium. The decreasing trend of reactivity with increasing burn-off in calcium-catalyzed oxidation is a result of interfacial contact loss because calcium does not have the necessary mobility to maintain such contact during reaction.