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On the phase chemistry of Portland cement clinker
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Cementa AB, Stockholm, Sweden. (Thermal Energy Conversion Laboratory)
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
Cementa AB, Malmö, Sweden.
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
2015 (Engelska)Ingår i: Advances in Cement Research, ISSN 0951-7197, E-ISSN 1751-7605, Vol. 27, nr 1, s. 50-60Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

This paper describes the formation of a phosphorous belite solid solution and its impact on alite formation. A sub-solidus phase relation for the ternary system silicon dioxide–calcium oxide–phosphorus pentoxide (SiO2–CaO–P2O5) is reported. The ternary system is based on Rietveld refinements of X-ray diffraction patterns from experimental tests. The overall picture is based on known phase diagrams, relevant Rietveld refinements models, stoichiometric relationships as a function of increasing phosphorus pentoxide concentration and vacancy theories for solid solutions of phosphate belites. A tool is developed for predicting the chemistry of the product as well as the chemistry during heating when producing Portland cement clinker. A thermodynamic database for phase chemistry calculations of clinkering reactions has been created and evaluated. Suitable compounds and solution species have been selected from the thermochemical database included in FactSage software. Some solution compositions have been uniquely designed to allow for the proper prediction of the cement clinker chemistry. The calculated results from the developed database for heating raw materials in cement clinker production and cooling of the product are presented in this paper. The calculated results provide a good prediction of the phases and quantities formed during heating and non-equilibrium cooling. The prediction of the amounts of alite, belite and aluminoferrite phases in the product according to the Scheil method is good. The temperature interval for the existence of all of the major phases is relevant. The thermodynamic data for a solution phase of alite with substituting ions of primarily magnesium oxide and phosphorus pentoxide would improve the predictability of the developed database.

Ort, förlag, år, upplaga, sidor
Thomas Telford, 2015. Vol. 27, nr 1, s. 50-60
Nationell ämneskategori
Kemiska processer
Identifikatorer
URN: urn:nbn:se:umu:diva-89699DOI: 10.1680/adcr.13.00071ISI: 000351286400007Scopus ID: 2-s2.0-84937510640OAI: oai:DiVA.org:umu-89699DiVA, id: diva2:722998
Tillgänglig från: 2014-06-10 Skapad: 2014-06-10 Senast uppdaterad: 2023-08-22Bibliografiskt granskad
Ingår i avhandling
1. Modeling the influence of magnesium from alternative raw materials on the chemistry of Portland cement clinker
Öppna denna publikation i ny flik eller fönster >>Modeling the influence of magnesium from alternative raw materials on the chemistry of Portland cement clinker
2023 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Alternativ titel[sv]
Modellering av inverkan av magnesium från alternativa råmaterial på Portland cementklinker kemi
Abstract [en]

The methods used in this thesis work were a combination of computational and modeling based laboratory experiments.

Thermodynamic process modeling of the cement clinker process offers a tool for evaluating how changes in raw materials and process parameters affect the clinker quality. Work with finding suitable replacement raw materials involves investigating the chemical compatibility of potential alternative materials. Such replacement materials may be metallurgical slags, although there are some unsolved issues with the quantities of certain metals and particularly Mg in these materials.

For predicting the formation of clinker mineral phases, cooling calculations are used in order to reproduce the temperature history in the full scale process. A chemistry model including a solid solution phase based on C2S and phosphate was developed along with the recommendation for continued work on clinker phases with solid solutions to include MgO. A thermodynamic database for phase chemistry calculations of clinkering reactions was created and evaluated. Suitable compounds and solution species were selected from the thermochemical database included in FactSage software. The extent and quality of the required thermodynamic data via available databases is generally satisfactory, except for certain properties of some of the main clinker phases. One example is the lack of a thermodynamic model for the alite solid solution. That is, the composition of the phase available in the database representing alite does not contain the minor elements Al, Fe and Mg. Therefore, it is difficult to predict the quantity and distribution of Mg in the clinker, with varying total content of MgO. Thus, one of the goals/objectives was to improve thethermodynamic model of alite as a solid solution of 3CaO-SiO2-xAl2O3-yFe2O3-zMgO. To achieve this, it was assumed that a mix of compounds with adjusted Henrian coefficients representing the solid solution clinker phase alite was in equilibrium with the clinker melt.

The distribution of MgO was studied in synthetic clinker compositions with quantities ranging from 0.5 to 10 wt-%. Synthetic clinker mixes were heated to 1450°C and studied with Rietveld refinements of X-ray diffraction data and SEM-EDS analysis. In addition, the mechanisms of how slag and lime particles react facilitating the diffusion of MgO into the developing clinker melt and the formation of incipient belite were studied.

The calculated results provide a good prediction of the quantities and composition of the clinker phases formed during heating and non-equilibrium cooling. The solubility of MgO in the clinker and the quantity of periclase formed is in fair agreement with published data. Thus, this thesis work shows that using a mix of compounds with adjusted activities in alite together with available standard thermodynamic data and the Scheil cooling method had good potential for evaluating alternative raw materials.

Also, the work has identified weak points in the process modeling and suggest improvements to be made in future research work.

Ort, förlag, år, upplaga, sidor
Umeå: Umeå universitet, 2023. s. 94
Nyckelord
Thermodynamic modeling, process modeling, Portland cement, clinker, periclase, magnesium oxide, alite, Scheil calculation, solid solutions
Nationell ämneskategori
Fysikalisk kemi Kemiska processer
Forskningsämne
fysikalisk kemi
Identifikatorer
urn:nbn:se:umu:diva-213098 (URN)9789180700863 (ISBN)9789180700856 (ISBN)
Disputation
2023-09-14, Aula Biologica, Biologihuset, Umeå, 13:00 (Svenska)
Opponent
Handledare
Forskningsfinansiär
Vinnova, 2014-04073Vinnova, 2015-02519Vinnova, 2015-04541Energimyndigheten
Tillgänglig från: 2023-08-24 Skapad: 2023-08-21 Senast uppdaterad: 2023-08-22Bibliografiskt granskad

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Hökfors, BodilBoström, DanViggh, ErikBackman, Rainer

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