Fundamentals of silico-ferrite of calcium and aluminium (SFCA) and SFCA-I iron ore sinter bonding phase formation: effects of mill scale addition

2017 ◽  
Vol 32 (S2) ◽  
pp. S85-S89 ◽  
Author(s):  
Nathan A. S. Webster ◽  
Mark I. Pownceby ◽  
Rachel Pattel
Keyword(s):  
Iron Ore ◽  
Amorphous Material ◽  
Quantitative Phase Analysis ◽  
X Ray Diffraction ◽  
Mill Scale ◽  
Iron Ore Sinter ◽  
External Standard Method ◽  
Mineral Sample ◽  
Sinter Bonding

The thermal decomposition of mill scale, and the effect of mill scale addition on the formation and decomposition of Silico-Ferrite of Calcium and Aluminium (SFCA) and SFCA-I iron ore sinter bonding phases, has been investigated using in situ X-ray diffraction. Application of the external standard method of quantitative phase analysis of the in situ data collected during decomposition of the mill scale highlighted the applicability of this method for the determination of the nature and abundance of amorphous material in a mineral sample. Increasing mill scale addition from 2.6 to 10.6 and to 21.2 wt% in an otherwise synthetic sinter mixture composition designed to form SFCA did not significantly affect the thermal stability ranges of SFCA-I or SFCA, nor did it significantly affect the amount of each of SFCA or SFCA-I, which formed. This was attributed to the low impurity (i.e. Mn, Mg) concentration in the mill scale, and also the transformation to hematite during heating of the wüstite and magnetite present in the mill scale, with the hematite available for reaction to form SFCA and SFCA-I.

In situ diffraction studies of iron ore sinter bonding phase formation: QPA considerations and pushing the limits of laboratory data collection

2014 ◽  
Vol 29 (S1) ◽  
pp. S54-S58 ◽  
Author(s):  
Nathan A. S. Webster ◽  
Mark I. Pownceby ◽  
Ian C. Madsen ◽  
Andrew J. Studer ◽  
Justin A. Kimpton
Keyword(s):  
Phase Formation ◽  
Iron Ore ◽  
Laboratory Data ◽  
Quantitative Phase Analysis ◽  
Heating Rates ◽  
Iron Ore Sintering ◽  
Iron Ore Sinter ◽  
Ore Sintering ◽  
Sinter Bonding

The formation and decomposition of silico-ferrite of calcium and aluminium (SFCA) and SFCA-I iron ore sinter bonding phases have been investigated using in situ synchrotron and laboratory X-ray diffraction (XRD) and neutron diffraction (ND). An external standard approach for determining absolute phase concentrations via Rietveld refinement-based quantitative phase analysis is discussed. The complementarity of in situ XRD and ND in characterising sinter phase formation and decomposition is also shown, with the volume diffraction afforded by the neutron technique reducing errors in the quantification of magnetite above ~1200 °C. Finally, by collecting 6 s laboratory XRD datasets and using a heating rate of 175 °C min−1, phase formation and decomposition have been monitored under heating rates more closely approximating those encountered in industrial iron ore sintering.

In situX-ray diffraction analysis of iron ore sinter phases

2004 ◽  
Vol 37 (3) ◽  
pp. 362-368 ◽  
Author(s):  
Nicola V. Y. Scarlett ◽  
Ian C. Madsen ◽  
Mark I. Pownceby ◽  
Axel N. Christensen
Keyword(s):  
Iron Ore ◽  
Rietveld Method ◽  
Structural Type ◽  
X Ray Diffraction ◽  
X Ray ◽  
Intermediate Phases ◽  
Iron Ore Sinter ◽  
Phase Quantification ◽  
Bonding Phase

Owing to the depletion of world lump iron ore stocks, pre-treated agglomerates of fine ores are making up a growing proportion of blast-furnace feedstock (∼80%). These agglomerations, or `sinters', are generally composed of iron oxides, ferrites (most of which are silicoferrites of calcium and aluminium, SFCAs), glasses and dicalcium silicates (C2S). SFCA is the most important bonding phase in iron ore sinter, and its composition, structural type and texture greatly affect its physical properties. Despite its prevalence and importance, the mechanism of SFCA formation is not fully understood.In situpowder X-ray diffraction investigations have been conducted into the formation of SFCA, allowing the study of the mechanism of its formation and the observation of intermediate phases with respect to time and temperature. Studies have been carried out to investigate the effects of changing the substitution levels of aluminium for iron. The use of the Rietveld method for phase quantification gives an indication of the order and comparative rates of phase formation throughout the experiments.

In Situ Diffraction Studies: Thermal Decomposition of a Natural Plumbojarosite and the Development of Rietveld-Based Data Analysis Techniques

2010 ◽  
Vol 651 ◽  
pp. 37-64 ◽  
Author(s):  
Ian C. Madsen ◽  
Ian E. Grey ◽  
Stuart J. Mills
Keyword(s):  
Thermal Decomposition ◽  
Amorphous Material ◽  
Data Sets ◽  
X Ray Diffraction ◽  
Data Set ◽  
X Ray ◽  
Analysis Techniques ◽  
Path Lengths ◽  
Instrument Configuration

A study of the thermal decomposition sequence of a sample of natural arsenian plumbojarosite has been undertaken using in situ X-ray diffraction. The sample was heated to 900°C using an Anton-Paar heating stage fitted to an INEL CPS120 diffractometer. The data were analysed using a whole-pattern, Rietveld based approach for the extraction of quantitative phase abundances. The instrument configuration used required the development and application of algorithms to correct for aberrations in the (i) peak intensities due to differing path lengths of incident and diffracted beams in the sample and (ii) peak positions due to sample displacement. Details of the structural models used were refined at selected steps in the pattern and then fixed for subsequent analysis. The data sequence consists of some 110 individual data sets which were analysed sequentially with the output of each run forming the input for analysis of the next data set. The results of the analysis show a complex breakdown and recrystallisation sequence including the formation of a major amount of amorphous material after initial breakdown of the plumbojarosite.

scholarly journals Hydration Study of Synthetic Yeelimite using LXRPD and SXRPD

2014 ◽  
Vol 70 (a1) ◽  
pp. C1096-C1096
Author(s):  
Ana Cuesta ◽  
Gema Alvarez Pinazo ◽  
Angeles De la Torre ◽  
Susana Sanfélix ◽  
Inmaculada Peral ◽  
...  
Keyword(s):  
Standard Method ◽  
Internal Standard ◽  
Free Water ◽  
Ex Situ ◽  
Quantitative Phase Analysis ◽  
Internal Standard Method ◽  
X Rays ◽  
X Ray ◽  
External Standard Method

XRPD is a powerful tool for material characterization in general, and for in-situ studies of chemical processes in particular. The use of an intense X-ray source, .i.e. synchrotron X-rays, coupled with fast X-ray detection permits time-resolved diffraction experiments allowing in-situ quantitative phase analysis during the early ages of cement hydration. Calcium sulfoaluminate, CSA, cements may have variable compositions, but all of them contain high amounts of ye'elimite, Ca4Al6O12SO4. Commercial CSA cements have special applications such as high strength developments at early-ages. Ye'elimite is very reactive and most of its hydration heat is released during the first eight hours of hydration . The aim of this work is to better understand the early age hydration of stoichiometric (orthorhombic) and doped (pseudo-cubic) ye'elimite samples. The parameters studied by SXRPD, LXRPD and calorimetry have been: polymorphism; water/ye'elimite ratio; and sulfate (gypsum and anhydrite) contents. This work has allowed establishing mechanisms and kinetics for hydration of ye'elimite samples by in-situ SXRPD with internal standard methodology. Moreover, pastes were also studied by ex-situ LXRPD with the external standard method, G-factor, at 2 and 7 days. Both strategies were able to quantify the amorphous contents, including free water. It is important to highlight that the results obtained at early ages, by the internal standard method, are in agreement with those obtained at later ages, G-method, showing the consistence and complementarity of both methodologies. The hydration of stoichiometric ye'elimite in the presence of gypsum is strongly hastened, when compared to the hydration process without gypsum. However, the presence of gypsum has a little effect in the hydration of doped ye'elimite. Moreover, anhydrite has also accelerated the hydration of stoichiometric ye'elimite, although its lower solubility has provoked the formation of an intermediate phase in the first hours.

scholarly journals In situ high-energy X-ray diffraction study and quantitative phase analysis in the α+γ phase field of titanium aluminides

2007 ◽  
Vol 57 (12) ◽  
pp. 1145-1148 ◽  
Author(s):  
LaReine A. Yeoh ◽  
Klaus-Dieter Liss ◽  
Arno Bartels ◽  
Harald Chladil ◽  
Maxim Avdeev ◽  
...  
Keyword(s):  
Diffraction Study ◽  
Phase Analysis ◽  
Phase Field ◽  
Titanium Aluminides ◽  
High Energy ◽  
Quantitative Phase Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Quantitative Phase

Quantitative in situ X-ray diffraction analysis of early hydration of Portland cement at defined temperatures

2009 ◽  
Vol 24 (2) ◽  
pp. 112-115 ◽  
Author(s):  
C. Hesse ◽  
F. Goetz-Neunhoeffer ◽  
J. Neubauer ◽  
M. Braeu ◽  
P. Gaeberlein
Keyword(s):  
Portland Cement ◽  
Free Water ◽  
Xrd Analysis ◽  
Quantitative Phase Analysis ◽  
X Ray Diffraction ◽  
Early Hydration ◽  
X Ray ◽  
Main Period ◽  
Diffraction Patterns

Investigation into the early hydration of Portland cement was performed by in situ X-ray diffraction (XRD). Technical white cement was used for the XRD analysis on a D5000 diffractometer (Siemens). All diffraction patterns of the in situ measurement which were recorded up to 22 h of hydration at defined temperatures were analyzed by Rietveld refinement. The resulting phase composition was transformed with respect to free water and C-S-H leading to the total composition of the cement paste. The hydration reactions can be observed by dissolution of clinker phases as well as by the formation of the hydrate phases ettringite and portlandite. With increasing temperatures the reactions proceed faster. The formation of ettringite is directly influenced by the rate of dissolution of anhydrite and tricalcium aluminate (C3A). The beginning of the main period of hydration is marked by the start of portlandite formation. The experiments point out that a quantitative phase analysis of the cement hydration is feasible with standard laboratory diffractometers.

Tracing the Alteration of Verdigris Pigment through Combined Raman Spectroscopy and X-ray Diffraction, Part II: Natural Ageing

2020 ◽  
Vol 41 (4) ◽  
pp. 177-203
Author(s):  
Lynn B. Brostoff ◽  
Cynthia Connelly Ryan ◽  
Isabella Black
Keyword(s):  
Raman Spectroscopy ◽  
Amorphous Material ◽  
Aqueous Media ◽  
Gum Arabic ◽  
Artificial Ageing ◽  
X Ray Diffraction ◽  
X Ray ◽  
Paint Films ◽  
First Time

AbstractThis study explores the natural alteration of verdigris, both in the form of neutral verdigris (Cu(II) (CH3COO)2⋅H2O) and basic verdigris (Cu(II)x(CH3COO)y(OH)z ⋅nH2O), through combined Raman spectroscopy and X-ray diffraction investigation of samples created seven to eleven years prior to analysis. The naturally aged paint films of neutral or basic verdigris in gum arabic on paper and parchment provide insight into the pigment’s well-known instability relevant to historical works in aqueous media on maps, prints, books and manuscript materials. The latter historical application is an area that has received far less attention than alteration of verdigris in oil-based paint films. Findings shed new light on alternate pathways for conversion of neutral verdigris to basic verdigris, including the formation of a previously unknown form of verdigris and amorphous material on alkaline paper substrates. Additionally, we demonstrate for the first time that copper hydroxyl chlorides can form in situ from neutral verdigris, in this case on parchment that has a chlorine-rich surface. These results advance our understanding of neutral verdigris alteration, and complement results from our prior artificial ageing study. Both studies point to neutral verdigris as the historically more important form throughout its heyday. Improved understanding of neutral verdigris instability and its alteration pathways are critical for confident identification of the pigment in historical works, leading to better risk assessment of collections of verdigris-containing heritage, such as maps.

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