Formation Of Tricalcium Silicate Research Articles

Coupled Preparation of Ferronickel and Cementitious Material from Laterite Nickel Ores.

Nickel slags can be produced through ferronickel preparation by the pyrometallurgical processing of laterite nickel ores; however, such techniques are underutilized at present, and serious environmental problems arise from the stockpiling of such nickel ores. In this study, a modification to the process of ferronickel preparation by the direct reduction of carbon bases in laterite nickel ores is proposed. The gangue from the ore is used as a raw material to prepare a cementitious material, with the main components of tricalcium silicate and tricalcium aluminate. By using FactSage software, thermodynamic calculations are performed to analyze the reduction of nickel and iron and the effect of reduction on the formation of tricalcium silicate and tricalcium aluminate. The feasibility of a coupled process to prepare ferronickel and cementitious materials by the direct reduction of laterite nickel ore and gangue calcination, respectively, is discussed under varying thermodynamic conditions. Different warming strategies are applied to experimentally verify the coupled reactions. The coupled preparation of ferronickel and cementitious materials with calcium silicate and calcium aluminate as the main phases in the same experimental process is realized.

Experimental Study on the Preparation of Cementing Materials by Direct Reduction Coupling of a Hematite-Carbon Base

The reduction of iron in hematite and process coupling of cementing material generated from gangue components are explored in this paper, and a technical proposal for preparing directly reduced iron and cementing materials considering the processes of energy and material flows is proposed. An experimental study preparing cementing materials, such as tricalcium silicate and dicalcium silicate, by roasting the components, was performed. In this study, hematite was used as the raw material and powdered carbon was added, as the reducing agent, with CaO; at the same time, the gangue components of iron ore were used as the principal raw materials for the process of directly reduced iron preparation by direct reduction of iron ore. The FactSage software package was used to perform thermodynamic calculations of the reduction of iron and its influence on the formation of tricalcium silicate and dicalcium silicate. The feasibility of the direct reduction of iron to elemental iron and preparation of cementing materials by roasting of gangue components under the studied thermodynamic conditions was discussed. Different temperature control strategies were used to verify the reaction coupling test. The results showed that zero-valent iron could be produced by roasting and reducing hematite under certain experimental conditions, and cementing materials, such as tricalcium silicate and dicalcium silicate, could be produced simultaneously by reacting the gangue components with CaO. Fe2O3 exerted an adverse effect on the formation of tricalcium silicate, and sufficient reduction of the iron was a precondition for the formation and stability of tricalcium silicate.

Features of Tri-Calcium Silicate Formation Suppression by Sulphur and Possible Ways of its Preventing

Synthesis of the portland cement clinker in the presence of a significant amount of SO3 is difficult, due to the tri-calcium silicate formation suppression. Since some technogenic formations contain a significant amount of SO3, it is hard to obtain the portland cement clinker from it. The analysis of the SO3 influence on the clinker-formation thermodynamic process allowed to reveal a number of regularities of their occurrence and to propose a method for the raw mix composition calculating and its preparation, to ensure a stable portland cement clinker synthesis.

Difficulties of technogenic formations roasting products processing into the portland cement clinker in the presence of a significant amount of SO3

Synthesis of the portland cement clinker in the presence of a significant amount of SO3 is difficultdue to the tricalcium silicate formation suppression. Since some technogenic formations contain a significant amount of SO3 it is hard to obtain the portland cement clinker from it. The analysis of the SO3 influence on the clinker–formation thermodynamic process allowed to reveal a number of regularities of their occurrence and to propose a method for the raw mix composition calculating and its preparation toensure a stable portland cement clinker synthesis.

Dynamic Analysis of the Temperature and the Concentration Profiles of an Industrial Rotary Kiln Used in Clinker Production.

Cement is one of the most used building materials in the world. The process of cement production involves numerous and complex reactions that occur under different temperatures. Thus, there is great interest in the optimization of cement manufacturing. Clinker production is one of the main steps of cement production and it occurs inside the kiln. In this paper, the dry process of clinker production is analysed in a rotary kiln that operates in counter flow. The main phenomena involved in clinker production is as follows: free residual water evaporation of raw material, decomposition of magnesium carbonate, decarbonation, formation of C3A and C4AF, formation of dicalcium silicate, and formation of tricalcium silicate. The main objective of this study was to propose a mathematical model that realistically describes the temperature profile and the concentration of clinker components in a real rotary kiln. In addition, the influence of different speeds of inlet gas and solids in the system was analysed. The mathematical model is composed of partial differential equations. The model was implemented in Mathcad (available at CCA/UFES) and solved using industrial input data. The proposal model is satisfactory to describe the temperature and concentration profiles of a real rotary kiln.

Integrated Utilization of Sewage Sludge and Coal Gangue for Cement Clinker Products: Promoting Tricalcium Silicate Formation and Trace Elements Immobilization.

The present study firstly proposed a method of integrated utilization of sewage sludge (SS) and coal gangue (CG), two waste products, for cement clinker products with the aim of heat recovery and environment protection. The results demonstrated that the incremental amounts of SS and CG addition was favorable for the formation of tricalcium silicate (C3S) during the calcinations, but excess amount of SS addition could cause the impediment effect on C3S formation. Furthermore, it was also observed that the C3S polymorphs showed the transition from rhombohedral to monoclinic structure as SS addition was increased to 15 wt %. During the calcinations, most of trace elements could be immobilized especially Zn and cannot be easily leached out. Given the encouraging results in the present study, the co-process of sewage sludge and coal gangue in the cement kiln can be expected with a higher quality of cement products and minimum pollution to the environment.

Modelagem matemática de um forno rotativo empregado na produção de clínquer

Uma das principais etapas do processo de obtenção do cimento é a etapa de clinquerização, que ocorre dentro do forno rotativo. Em pleno funcionamento, o forno rotativo empregado na produção de cimento é alimentado basicamente de matéria-prima, combustível e ar. As vazões de saída são, basicamente, o clínquer e aos gases de combustão. Neste estudo, o processo de produção de clínquer por via seca é analisado, sendo a alimentação composta por 80% a 95% de calcário, 5% a 20% de argila e por pequenas quantidades de minério de ferro. O combustível empregado neste estudo é o carvão mineral. Os principais fenômenos envolvidos na obtenção do clínquer são a evaporação da água livre residual da matéria-prima, a decomposição do carbonato de magnésio, a descarbonatação, a formação da fase líquida do C3A e do C4AF, a formação do silicato dicálcico e a formação do silicato tricálcico. O objetivo principal deste estudo é a proposta de um modelo matemático que descreve o processo de obtenção do clínquer no forno rotativo. O modelo, composto por equações algébricas, foi desenvolvido por meio de balanços de massa e energia do forno. A modelagem foi implementada em linguagem de programação, empregando-se um programa comercial. A condição operacional considerada representa uma condição média adotada na indústria. O modelo proposto se mostrou satisfatório para a descrição do processo de clinquerização, sendo especialmente útil na realização da análise da demanda energética do equipamento.

Formation of Tricalcium Silicate Prepared by Electric and Microwave Sintering

A microwave sintering method was used to prepare C3S from Ca(OH)2, SiO2 and MexOy. f-CaO assay, X-ray diffraction and SEM were used to characterize the sintered samples.The results indicated that ion oxides played a very important role in C3S formation in conventional sintering, the use of MexOy as an additive was so effective in promoting C3S formation. The experimental results showed that samples were heated at an electric heating temperature(1500°C) and then further sintered with microwave for 30~60 min, tricalcium silicate could be formed with kilogram step. The new burning technique can greatly increase the forming speed of tricalcium silicate, MnO2, CuO and Ni2O3 could enhance the microwave sintering.

Reuse of heavy metal-containing sludges in cement production

The feasibility of the replacement of raw material for cement production by heavy metal-containing sludge from surface finishing and electroplating industries was investigated. The effect of heavy metal content in the cement raw mix on the crystalline formation in cement production was also examined by XRD analyses. It was found that both sludges were applicable for the replacement of raw mix for cement production by moderate conditioning of the sludge compositions with several compositional parameters. As the replacement of raw mix by sludge was within 15%, the formation of tricalcium silicate (C 3S) phase in cement would be enhanced by the introduced heavy metals. While owing to a high level of heavy metals concentration (> 1.5%) in cement raw mix, C 3S crystalline in cement would be inhibited by a large sludge replacement (> 15%). During the sintering process, over 90% of the high volatile elements such as Pb would evaporate in high temperature, yet 90% of the less volatile elements such as Cu, Cr and Ni would be trapped in clinkers. Most of all, the results of leaching test shows that the trapped elements in hydrated samples would not leach out under acidic conditions. The reuse of heavy metal-containing sludges as cement raw material would not cause leaching hazard from sintered clinkers. Heavy metal-containing sludges thus should have the potential to be utilized as alternative raw materials in cement production.

Etude de la reactivite de crus de cimenterie: Comportement cinetique de la combinaison de la chaux au cours du processus de clinkerisation

Summary This paper addresses the kinetics of lime combination and the direct link that exists between the mechanism of the transformation of cement raw meal and the mode of heating during the calcination. Experiments performed in the laboratory revealed that the kinetics of lime combination involves two stages : a first stage of formation of dicalcium silicate from the lime and the silica, followed by a second stage corresponding to the formation of tricalcium silicate from the dicalcium silicate already produced with the remaining lime and melt in the reaction medium. By applying the theoretical models of heterogeneous kinetics to experimental curves, obtained during isothermal and nonisothermal heating, the kinetic analyses suggest that the lime combination is controlled by volume diffusion in the grains. This reactivity is closely connected to the mode of heating during the clinkering process.

Effect of barium on the formation of tricalcium silicate

The effect of barium carbonate on the kinetics of tricalcium silicate formation has been studied. Burnability study of mixes of calcium carbonate and quartz in 3:1 ratio and barium carbonate equivalent to 0.5 to 4% BaO by weight showed accelerated rate of clinkerisation through mineralising action. The addition of BaCO 3 significantly reduced the time and temperature of formation of C 3S. At 1450°C up to 1.85% BaO could be assimilated in forming solid solution of C 3S. With up to 2% BaO triclinic form and 4% BaO, monoclinic form of C 3S was stabilised. The solubility of BaO in C 3S at 1450°C was investigated using chemical analysis (estimation of free lime) and energy dispersive analysis of X-rays. The limit of solubility is found to be 1.85% (by weight) at 1450°C. Above the solubility limit, BaO formed Ba 3SiO 5 at 1450°C.

Thermodynamics driving force for formation of tricalciumsilicate

Thermodynamics driving force for formation of tricalciumsilicate

A Calculation of the Change in Free Energy in the Formation of Tricalcium Silicate from Calcium Oxide and β-Dicalcium Silicate

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTA Calculation of the Change in Free Energy in the Formation of Tricalcium Silicate from Calcium Oxide and β-Dicalcium SilicateHugh A. ShadduckCite this: J. Phys. Chem. 1937, 41, 4, 625–628Publication Date (Print):April 1, 1937Publication History Published online1 May 2002Published inissue 1 April 1937https://doi.org/10.1021/j150382a012RIGHTS & PERMISSIONSArticle Views45Altmetric-Citations2LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (180 KB) Get e-Alerts

Studies on the Thermochemistry of the Compounds Occurring in the System CaO—Al2O3—SiO2. V. The Heats of Formation of Tricalcium Silicate and Dicalcium Silicate1

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStudies on the Thermochemistry of the Compounds Occurring in the System CaO—Al2O3—SiO2. V. The Heats of Formation of Tricalcium Silicate and Dicalcium Silicate1O. K. Johannson and T. ThorvaldsonCite this: J. Am. Chem. Soc. 1934, 56, 11, 2327–2330Publication Date (Print):November 1, 1934Publication History Published online1 May 2002Published inissue 1 November 1934https://doi.org/10.1021/ja01326a032RIGHTS & PERMISSIONSArticle Views76Altmetric-Citations12LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (437 KB) Get e-Alerts Get e-Alerts