Reaction Kinetics of LiOH· H2O and CO2 Improved with Composite Silica Gel of Lanthanum Chloride

Reaction kinetics of LiOH·H2O and C·2 within a closed system were studied under the adsorption of water vapor by composite silica gel of lanthanum chloride. At the reaction temperature of 273~323K and initial CO2 pressures of 40~100kPa, reaction kinetics obeyed the Erofeev model. The reaction rate decreased slightly while the initial CO2 pressure reduced. When the reaction occurred at 273~299K, the reaction rate was so low that it was almost independent of the reaction temperature. However, as the temperature rose up to 300~323K, LiOH·H2O dehydrated its crystal water, and both the dehydrated and reaction-generated water were evaporated from solid reactant. For the dehydration rate increased, the reaction rate also increased as the reaction temperature rose. While the temperature was higher than 323K, the reaction apparent activation energy of LiOH·H2O and CO2, was higher than 52.5kJ·mol-1 and close to 61.4kJ·mol-1 of the LiOH·H2O dehydrated enthalpy variable at 298K, in which anhydrous LiOH was the major reactant and showed the reaction characteristics of LiOH crystals.     

Roles of Ceria on Copper and Manganese Oxides Catalyst——Adsorption of NO and CO

A microreactor system and TPD techniques were used to study the reaction kinetics of the CO+NO reaction and the adsorption of CO,NO,CO_2 and N_2O over Cu-Mn-O(Ⅰ)and Cu-Mn-Ce-O(Ⅱ)catalysts.The results show that the catalytic activity of(Ⅱ)is higher than that of(Ⅰ)for the CO+NO reac-tion,and the higher the conversion of NO,the larger was the activity difference between(Ⅰ)and(Ⅱ).For(Ⅰ)the rate of NO elimination is dependent on the partial pressures of NO,CO,CO_2 with the kinetics or-ders of 0.48,0.56,0.08,respectively.The TPD study shows that the presence of Ce in(Ⅱ)may promote theadsorption of NO,CO on the surface,i.e.an increase of the coverage θ_(NO),θ_(CO),which result in a decrease ofthe hindrance of the reaction products.For CO_2 and N_2O the situation is in the opposite,the presence of Cemakes the θ_(CO)_2)and θ_(NO)on(Ⅱ)decrease,which weakens the inhibition of CO_2 for the reaction.     

Fluid–Solid Reaction Kinetics for Solids of Nonbasic Geometries and Determination of the Appropriate Shape Factors

Metallurgical and Materials Transactions B - The rate analysis involving a solid of nonbasic geometry in general requires a complex numerical solution. A closed-form expression of the reaction rate...     

Kinetics Analysis for the Parallel Reaction of Binary Rare Earth with Tribromoarsenazo

The overall reaction was determined on the basis of the dissociation constant of TBA and the ratio of theligand to the rare earth ion in the complex.The rate law,rate constants and acitivition energies for the reactionof La~(3 ),Gd~(3 )and Ho~(3 )with TBA were studied.It is shown in the study that prerequisites for performingdifferential rate analysis for binary rare earths with TBA are that the pseudo-first-order parallel reactionmechanism should be conformed with,no multinuclear complex would be formed and the co-coloration effectscould be neglected.     

Liquid steel transfer—the delivery of quality

During recent years, in parallel with developments in high-speed casting, there have been increasing demands for improved steel quality. These demands are being met by advances in our knowledge of the chemical, physical and thermal interactions between steel, gas, slag and refractory phases which take place within individual reactors as well as during transfer operations. Transfer operations must be precisely controlled, otherwise they become destroyers of quality, and quality achieved within one reactor can be lost during transfer to the next.     

Kinetics of sub-grain coalescence—A reconsideration of the theory

The theory for the kinetics of sub-grain coalescence originally developed by Li [J. appl. Phys.33, 2958 (1962)] has been modified; the original theory significantly underestimates the observed times for coalescence in aluminium at temperatures below 350°C. The first modification considers the climb mobility of dislocationloops rather than that of isolated edge dislocations. For mobility limited by bulk diffusion the result is similar to that given by Li, but mobility limited by pipe diffusion is possible for dislocation loops and is found to give much higher mobilities at temperatures less than 350°C. An additional modification is the relaxation of Li's assumption of a uniform dislocation array now known to be incorrect. A simple computer simulation of coalescence by independent climb of a set of dislocation loops, is shown to give non-uniform dislocation distributions very similar to those observed. In combination with the pipe diffusion model for climb mobility, the simulation matches the reported kinetics of coalescence. Finally, the model for coalescence developed here, involving interaction of different dislocation loops, is shown to account for the known heterogeneity of sites for coalescence in aluminium. It is predicted that coalescence requirestwo adjacent high-angle boundaries to act as dislocation sinks.     

The Physical Chemistry of Copper Smelting Slags and Copper Losses at the Paipote SmelterPart 2 – Characterisation of industrial slags

Abstract

The results of an investigation on copper losses in industrial slag from the Teniente converter (TC) and from the electrical slag cleaning furnace (EF) at the Paipote smelter in Chile are presented. Slag samples from each furnace were characterised using chemical and mineralogical techniques. The distribution of the various phases, including entrained matte, was quantified by semi-automatic image analysis. The level of soluble copper was measured by EPMA on samples cooled at a fast cooling rate. The phases found in the slag samples after such cooling are in agreement with thermodynamic calculations of the solidification process. Two types of magnetite crystals were observed in the TC slag samples: magnetite formed during slag solidification (type II) and magnetite which was present as a solid in the melt (type I). The portion of magnetite (type I) was found negligible in the EF slag samples. Sulphide phases were identified in the slag samples as solidified entrained matte, and sulphides present via ex-solution from the liquid slag during solidification. In the case of the TC, the present study has shown that with ～4·6 wt-%Cu in slag, about 87% was present as entrained matte. For the electrical furnace, the amount of entrained matte represents some 25% of the copper when the average copper level in EF slag samples was ～0·74 wt-%Cu.

Les résultats d'une étude sur les pertes en cuivre dans les laitiers du convertisseur Teniente (TC) et du four électrique (EF) de nettoyage du laitier de la fonderie de Paipote au Chili sont présentés. On a caractérisé des échantillons de laitier de chaque four en utilisant des techniques chimiques et minéralogiques. On a quantifié la distribution des diverses phases, incluant la matte entraînée, au moyen de l’analyse d’image semi-automatique. On a mesuré le niveau de cuivre soluble par EPMA sur des échantillons refroidis à un taux rapide de refroidissement. Les phases retrouvées dans les échantillons de laitier après un tel refroidissement sont en accord avec les calculs thermodynamiques du processus de solidification. On a observé deux types de cristaux de magnétite dans les échantillons de laitier du TC: la magnétite formée lors de la solidification du laitier (type II) et la magnétite présente sous forme solide dans le bain (type I). On a trouvé que la portion de magnétite (type I) était négligeable dans les échantillons de laitier du EF. Les phases de sulfure provenant de la matte entraînée solidifiée et les phases de sulfure formées par ex-solution du laitier durant la solidification ont été identifiées dans les échantillons industriels. Dans le cas du convertisseur Teniente, l’étude présente a montré qu’avec ～4·6 wt-% de Cu dans le laitier, environ 87% du cuivre était présent sous la forme de matte entraînée. Pour le four électrique, la quantité de matte entraînée représente quelque 25% du cuivre lorsque le niveau de cuivre moyen dans les échantillons de laitier du EF était de ～0·74 wt-%Cu.     

Reaction of Tungsten with Liquid Co ― Sn Alloys

The solubility of tungsten in Co Sn melts and the growth kinetics of a W₆Co₇ phase layer at the tungsten melt interface were studied at 1200°C. The liquid alloys composition in the three-phase equilibrium W W₆Co₇ melt was established as (at. fraction) 0.51 Co, 0.49 Sn, 2.3·10^–3 W. The solubility of tungsten in the investigated range of melt compositions is well represented by the equation lgx _W = –0.964-3.420x _Sn, where x _W and x _Sn are atomic fractions of the elements in the melt. The calculated thermodynamic properties can be used for the analysis of other systems which include cobalt and tungsten.     

The Redox Kinetics of the Oxidation for CO on EuFeO_3 Catalyst

ＴｈｅＲｅｄｏｘＫｉｎｅｔｉｃｓｏｆｔｈｅＯｘｉｄａｔｉｏｎｆｏｒＣＯｏｎＥｕＦｅＯ_３ＣａｔａｌｙｓｔＺｈａｎｇＲｕｉｑｉｎ（张瑞芹）；ＹｕＱｉｑｕａｎ（俞启全）；ＪｉｎＹｕｎ（金韵）（ＤｅｐａｒｔｍｅｎｔｏｆＣｈｅｍｉｓｔｒｙ，ＰｅｋｉｎｇＵｎｉ?..     

Kinetics and Mechanism of Chlorination of Alumina Grains with He–CO–Cl2 Gas Mixtures—II. Intrinsic Rates and Effectiveness Factors

Abstract

The experimental results reported in Part I[1] for the chlorination of porous samples composed of alumina grains are correlated here using a coupled pore-diffusion/surface-reaction model. The reactant gases CO and Cl₂ diffuse inwards through the interstices between the grains and simultaneously react with grain-surfaces producing AlCl₃ and CO₂, Values for the intrinsic rate constant, k_w, were deduced from the measured rates by correcting for the mass-transfer effects.

ln k _w = ?2.1535(±0.3729) ? 9615(±426)T^?1

where k_w is mole Al₂O₃ reacted per g of solid-grain-sample per atm² per s. The effectiveness factors for the chlorination reaction were small, ranging between 0.136 and 0.374, indicating that the pore-diffusion of reactant species is relatively slow as compared to the second-order surface reaction. The activation energy for chlorination was found to be 79.94 (± 3.54) kJ.mol^?1 in the temperature range 800–950°C.     

Link between the Semi-empirical Andrade and Schytil Equations and the Statistical-Mechanical Born–Green Equation for Viscosity and Surface Tension of Pure Liquid Metals

The semi-empirical Andrade and Schytil equations are revisited for the melting point dynamic viscosity and surface tension of pure liquid metals. Both equations are derived in modified forms, with easy-to-use, dimensionless semi-empirical parameters. The modified equations are used to reproduce the theoretical equation of Born–Green on the ratio of surface tension and viscosity of pure liquid metals.     

Roles of Ceria on Base Metal Oxide Catalysts——NO+CO Reaction

A microreactor system was used to study the catalytic reaction of NO+CO→1/2 N_2+CO_2 over Cu,Fe,Mn,Cr,and Ce oxides supported on alumina,and the effect of adding Ce in supported Cu-M-O(M=Mn,Feand Cr) catalysts on their catalytic activities for the topic reaction and the concentration of N_2O produced.Itwas found that the catalytic activity order of the single-element oxide is:CuO>Fe_2O_3≈Cr_2O_3>MnO_2>CeO_2>NiO.Cu-Mn-O is more active than CuO,and Cu-Fe-O is more active than Cu-Mn-O andCu-Cr-O for NO+CO reaction.This study shows that the addition of Ce in supported Cu-M-O can promotetheir catalytic activities Jot the topic reaction,which makes the reaction of 2NO+CO→N_2O+CO_2 fast,andN_2O is an intermediate compound produced during NO+CO reaction.     

Development of China's Copper Plate and Strip Industry——Part Ⅱ

正In China,the upstream industries of copper processing are copper ore dressing and copper smelting industries.But China's copper industry has seen unbalanced development between the three steps:copper ore dressing,copper smelting and processing.The industrialpattern where processing capacity is greater than smelting capacity,and smelting capacity is     

Development of China's Copper Plate and Strip Industry——Part Ⅰ

正As a metal,copper comes in third only to iron and aluminum in terms of importance in national economy and as a non-ferrous metal,it ranks second in terms of consumption.The copper industry is a pillar of the non-ferrous metal industry in China.In 2016,the copper industry's assets accounted for23%of the national non-ferrous industry's total,and its income accounted for 35%.China also holds an