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  • 1.
    Aguirre Castillo, José
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. Heidelberg Materials Cement Sverige AB, Slite, Sweden.
    Broström, Markus
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Eriksson, Matias
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. Swedish Mineral Processing Research Association (MinFo), Stockholm, Sweden.
    Phase evolution and burnability of cement raw meal2023In: Advances in Cement Research, ISSN 0951-7197, E-ISSN 1751-7605, Vol. 35, no 12, p. 577-587Article in journal (Refereed)
    Abstract [en]

    The use of high-temperature X-ray diffraction (HT-XRD) to study the mass transfer of raw meal constituents towards forming clinker phases and the occurrence of free lime (calcium oxide), also known as burnability, was assessed. A measuring strategy with temperature ranging from 1000°C to 1450°C was developed and compared with a conventional burnability method. The free lime determined by the methods showed that HT-XRD produced good results for the evaluation of burnability. In addition, HT-XRD revealed the formation of intermediate phases, providing insight into early reactions in a cement kiln. The particle size of quartz was found to affect crystal expansion of the phase at a high temperature, subsequently affecting the formation of silica polymorphs. The different raw meals used in this study also indicate that the formation of different silica polymorphs affects the formation of C2S. The lack of knowledge regarding the influence of β-quartz on the reduction of free lime is highlighted.

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  • 2.
    Hökfors, Bodil
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. Cementa AB, Stockholm, Sweden.
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Viggh, Erik
    Cementa AB, Malmö, Sweden.
    Backman, Rainer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    On the phase chemistry of Portland cement clinker2015In: Advances in Cement Research, ISSN 0951-7197, E-ISSN 1751-7605, Vol. 27, no 1, p. 50-60Article in journal (Refereed)
    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.

  • 3.
    Hökfors, Bodil
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. Cementa AB, Stockholm, Sweden.
    Eriksson, Matias
    NorFraKalk, Verdal, Norway.
    Viggh, Erik
    Cementa AB, Malmö, Sweden.
    Modelling the cement process and cement clinker quality2014In: Advances in Cement Research, ISSN 0951-7197, E-ISSN 1751-7605, Vol. 26, no 6, p. 311-318Article in journal (Refereed)
    Abstract [en]

    This paper presents a recently developed simulation model that can be used as a tool for evaluating sustainable development measures for cement and lime production processes. Examples of such measures are introducing new combustion technologies such as oxy-fuel combustion, using biomass fuel and using alternative materials in the raw material feed. One major issue when introducing process changes is the need to maintain product quality. In some ways, oxygen-enriched air combustion resembles oxy-fuel combustion. The model results were validated and found to be consistent with full-scale operational data for normal running conditions and for a full-scale test with oxygenenriched air. The model shows, for example, that with an additional 1500 m3/h of oxygen, fuel addition at the calciners can increase up to 108% and the raw material feed rate can increase up to 116% for a process with a raw meal feed of 335.5 t/h.

  • 4.
    Hökfors, Bodil
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. Cementa AB, Stockholm, Sweden.
    Viggh, Erik
    Cementa AB, Malmö, Sweden.
    Eriksson, Matias
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. NorFraKalk, Verdal, Norway.
    Simulation of oxy-fuel combustion in cement clinker manufacturing2015In: Advances in Cement Research, ISSN 0951-7197, E-ISSN 1751-7605, Vol. 27, no 1, p. 42-49Article in journal (Refereed)
    Abstract [en]

    A thermodynamic process model is used as an evaluation tool. Full oxy-fuel combustion is evaluated for circulation of 20–80% of flue gases to the burn zone of a rotary kiln. The full oxy-fuel combustion simulations exhibit altered temperature profiles for the process. With 60% recirculation of flue gases, the temperature in the burn zone is comparable to the reference temperature, and carbon dioxide concentration in the flue gases increases from 33 to 76%. If water is excluded, carbon dioxide concentration is 90%. The partial oxy-fuel combustion method is evaluated for 20 and 40% recirculation of flue gases from one cyclone string to both calciners. Fuel and oxygen feed to the burning zone and calciners are optimised for the partial oxy-fuel scenario. The lowest specific energy consumption is desired while maximising the amount of carbon dioxide theoretically possible to capture. By introducing partial oxy-fuel combustion with 20% recirculation of flue gases in the carbon dioxide string, total carbon dioxide emissions increases by 4%, with 84% possible to capture. Within the limits of the model, the introduction of full oxy-fuel and partial oxyfuel combustion is possible while maintaining product quality. When simulating partial oxy-fuel combustion, the energy consumption will increase even when no power consumption for the production of oxygen is included.

  • 5.
    Viggh, Erik
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. Cementa AB, Malmö, Sweden.
    Eriksson, Matias
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. Nordkalk AB, Köping, Sweden.
    Wilhelmsson, Bodil
    R and D Cement Cementa AB, Stockholm, Sweden.
    Backman, Rainer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Early formation of belite in cement clinker raw materials with slag2021In: Advances in Cement Research, ISSN 0951-7197, E-ISSN 1751-7605, Vol. 33, no 6, p. 249-256Article in journal (Refereed)
    Abstract [en]

    Analytical methods for characterising cement raw meal during heating in different atmospheres were investigated. The effect of replacing limestone with 10 wt% slag on the formation of incipient belite and precursors of the clinker liquid in the temperature range 600–1050°C was quantified using thermogravimetry, X-ray diffraction and equilibrium calculations. The results showed that when calculating the lime saturation factor, slags were favoured to sand, resulting in lower amounts of quartz and C2S in the samples containing slag than the reference sample. This suggests that silicon dioxide in slag minerals did not react in this temperature range. The multi-component equilibrium results supported the phase formation sequence established. Allowing for the possible kinetic influences the potential solids solutions offered with the software was a valuable asset. The results showed that the effect of using slags to reduce the carbonate and sand content in a raw meal on potential amounts of incipient C2S was negative. At present, more detailed knowledge is needed regarding how blast-furnace slag and basic oxygen furnace slag contribute to the formation of intermediary compounds such as incipient C2S, C3A, C2F and C4AF in the solid phase at temperatures over 1050°C and affect the formation of C3S.

1 - 5 of 5
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