scholarly journals Determination of amorphous matter in industrial minerals with X-ray diffraction using Rietveld refinement.

2020 ◽  
Vol 56 (1) ◽  
pp. 1
Author(s):  
George Christidis ◽  
Katerina Paipoutlidi ◽  
Ioannis Marantos ◽  
Vasileios Perdikatsis

A great variety of fine grained industrial rocks, which are valued by the industry contain variable amounts of amorphous or poorly crystalline matter, which is not easily detectable by the conventional mineralogical analysis methods based on X-ray diffraction (XRD). The quantification of amorphous matter in industrial rocks is a major task because it provides a thorough characterization of the raw materials and assists to interpret their reactivity. Among the most reliable methods used for quantification of amorphous matter, are those which are based on Rietveld refinement. In this study we prepared 1:1 mixtures of synthetic or natural calcite and quartz with 5-80% glass flour and added corundum (α-Al2O3) internal standard and applied the Autoquan2.80 © software based on the BGMN computer code to quantify the amorphous matter content. The mixtures with synthetic minerals yielded results with minimum absolute error due to the similar particle size of the minerals, the internal standard and the glass. By contrast, the mixtures with natural minerals displayed greater relative error due to the particle size difference between the minerals on the one hand and the internal standard and the glass on the other, due to the microabsorption effect. Moreover, preferred orientation was important in the case of natural calcite, due to perfect  cleavage plane. Mixtures containing up to 25% amorphous matter did not display the characteristic hump at 20-30 °2θ, suggesting that the lack of the hump is not a safe criterion for the recognition of amorphous matter.

Minerals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 232
Author(s):  
Pedro J. Sánchez-Soto ◽  
Eduardo Garzón ◽  
Luis Pérez-Villarejo ◽  
George N. Angelopoulos ◽  
Dolores Eliche-Quesada

In this work, an examination of mining wastes of an albite deposit in south Spain was carried out using X-ray Fluorescence (XRF), X-ray diffraction (XRD), particle size analysis, thermo-dilatometry and Differential Thermal Analysis (DTA) and Thermogravimetric (TG) analysis, followed by the determination of the main ceramic properties. The albite content in two selected samples was high (65–40 wt. %), accompanied by quartz (25–40 wt. %) and other minor minerals identified by XRD, mainly kaolinite, in agreement with the high content of silica and alumina determined by XRF. The content of Na2O was in the range 5.44–3.09 wt. %, being associated with albite. The iron content was very low (<0.75 wt. %). The kaolinite content in the waste was estimated from ~8 to 32 wt. %. The particle size analysis indicated values of 11–31 wt. % of particles <63 µm. The ceramic properties of fired samples (1000–1350 °C) showed progressive shrinkage by the thermal effect, with water absorption and open porosity almost at zero at 1200–1250 °C. At 1200 °C, the bulk density reached a maximum value of 2.38 g/cm3. An abrupt change in the phase evolution by XRD was found from 1150 to 1200 °C, with the disappearance of albite by melting in accordance with the predictions of the phase diagram SiO2-Al2O3-Na2O and the system albite-quartz. These fired materials contained as main crystalline phases quartz and mullite. Quartz was present in the raw samples and mullite was formed by decomposition of kaolinite. The observation of mullite forming needle-shape crystals was revealed by Scanning Electron Microscopy (SEM). The formation of fully densified and vitrified mullite materials by firing treatments was demonstrated.


1988 ◽  
Vol 3 (3) ◽  
pp. 144-152 ◽  
Author(s):  
G. A. Raab

AbstractThe method described in this paper is a strict protocol for X-ray diffraction (XRD) analysis of mineral phases found in soils. Its application is not restricted to soils and is an attempt to standardize XRD sample preparation and analysis. The protocol requires the particle size of the < 2 mm - 0.002 mm fraction be reduced to 0.002 mm before analysis. In die qualitative section, the clay fraction ( < 0.002 mm particle size) is prepared as oriented slides. The suspended clay fraction is saturated with ethylene glycol, K +, and Mg+2; pipeted; air-dried; heat-treated at 110°C, 350°C, and 550°C; and X-rayed at each step in order to properly identify the clay minerals. In the quantitative section, the method employs a matrix-flushing agent, corundum (Al2O3). The corundum acts also as an internal standard, a calibration standard, and a reference standard. The suspended clay fraction is freeze-dried and corundum is added to each sample. Randomly oriented powder mounts are prepared from the < 2 mm - 0.002 mm fraction, and the < 0.002 mm fraction, and X-rayed. A series of reference standards are prepared based on the existing mineralogy, corundum is added, and each mixture is X-rayed. The software integrates the area under specific peaks (chosen for intensity and no overlap) in each sample, calculates the reference intensity ratios (RIRs) and calculates the percentage of each mineral based on the equation of Chung (1974). The attention to detail allows documentation and verification of the results yielding data of known quality.


2016 ◽  
Vol 680 ◽  
pp. 257-260
Author(s):  
Meng Yun Dong ◽  
Cheng Zhang ◽  
Jin Feng Xia ◽  
Hong Qiang Nian ◽  
Dan Yu Jiang

CaF2 nano-power was prepared by direct precipitation methods with Ca(NO3)2 and KF as raw materials. The influences of presintering temperature and sintering temperature on the particle size and distribution of CaF2 nano-power were studied by X-ray diffraction (XRD) and field-emission scanning electron microscopy (FESEM). This study provided an experimental method for preparation of CaF2 nano-power. The results show that the best presintering temperature of CaF2 nano-power is 500°C and the best sintering temperature of CaF2 ceramic is 900°C.


2006 ◽  
Vol 05 (04n05) ◽  
pp. 663-669 ◽  
Author(s):  
GANGQIANG ZHU ◽  
HONGYAN MIAO ◽  
GUOQIANG TAN ◽  
YUN LIU ◽  
AO XIA

Potassium bismuth titanate nanoparticles were prepared by the hydrothermal method using Ti ( C 4 H 9 O )4 and Bi ( NO 3)3·5 H 2 O as raw materials in alkaline solution at temperatures of 160–200°C. The crystal phase, particle size, morphology and dispersion of the particles were investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results show that the particles with sizes of about 50–100 nm in diameter are well-dispersed K 0.5 Bi 0.5 TiO 3 (KBT) crystals of tetragonal structure, and the alkaline concentration and the temperature of solutions have great effects on the phase composition and morphology of the resultant particles. We could gain the KBT phase of high purity when the concentration of KOH is about 8–12 M and the reaction temperature is about 170–180°C.


Clay Minerals ◽  
2015 ◽  
Vol 50 (5) ◽  
pp. 593-606 ◽  
Author(s):  
A. Nkalih Mefire ◽  
A. Njoya ◽  
R. Yongue Fouateu ◽  
J.R. Mache ◽  
N.A. Tapon ◽  
...  

AbstractThirty clay samples collected from three hills in Koutaba (west Cameroon) were characterized in order to evaluate their potential use as raw materials for ceramics. After preliminary mineralogical identification by X-ray diffraction, three representative samples from the three different hills, referred to hereafter as K1M, K2M and K3M, were selected for further investigation by X-ray fluorescence, plasticity, granularity and thermogravimetric analysis. The main clay minerals are kaolinite (32–51%) and illite (up to 12%). Additional major phases are quartz (32–52%), goethite (6–7%) and feldspars (0–4%). The chemical composition showed variable amounts of SiO2(60–72%), Al2O3(15–20%) and Fe2O3(1–9%), in accordance with the quartz abundance in all of the samples studied. The particle-size distribution showed a large proportion of silty fraction (64–88%) with moderate sandy (9–19%) and clayey fractions ( < 5% for K2M, 12% for K1M and 20% for K3M). All of the clays showed moderate plasticity-index values (8–11%). Because of these characteristics, K1M and K3M may be suitable for use in common bricks and hollow ceramic products. Sieving or the addition of ball clays is recommended to increase the plasticity of sample K2M for use in common bricks.


2012 ◽  
Vol 182-183 ◽  
pp. 52-56
Author(s):  
Jun Que Lu ◽  
Xiu Feng Wang ◽  
Hong Tao Jiang

Pure Bi12SiO20powder was successfully prepared by a molten salt method using Bi2O3and SiO2as raw materials and using KCl-K2CO3as flux at 635°C with the heating rate of 5°Cmin-1. The phase composition and microstructure of these products were analyzed by X-ray diffraction and scanning electron microscopy, and the effects of the processing parameters, such as the ratio of Bi2O3/SiO2, calciniation temperature, isothermal time and relative amount of salt, on the composition and particle size were investigated. The results indicated that regardless of changing the ratio of Bi2O3/SiO2, calciniation temperature, isothermal time or relative amount of salt the reaction only yielded Bi12SiO20without Bi2SiO5and Bi4Si3O12. Henceforth, KCl-K2CO3molten salts may be considered as an ideal reaction medium to synthesize pure phase of Bi12SiO20. The particle size of Bi12SiO20phase can be determined by changing the temperature, isothermal time and relative amount of salt.


2012 ◽  
Vol 499 ◽  
pp. 72-75 ◽  
Author(s):  
Yan Lu

Using three natural graphites with different particle size, 35, 50 and 80 mesh, as raw materials, expandable graphites were prepared by intercalating, water-washing and drying the natural graphites. The products were characterized by X-ray diffraction, Infrared spectroscopy, scanning electron microscope and Raman spectroscopy. Results show that the structure of expandable graphite is affected strongly by the particle size of natural graphite. With increasing the particle size of natural graphite, for expandable graphite, the expansion degree of graphite flakes along the c-axis and the relative ratio of intercalating agents increase, while the structural disorder increases.


1991 ◽  
Vol 6 (2) ◽  
pp. 70-73
Author(s):  
M.C. Osácar Soriano ◽  
J. Besteiro Ráfales ◽  
J. González Martínez

AbstractA procedure for Sr-analysis of vein barites by X-ray powder diffraction is described. It is based on the measurement of barite d210 spacing change referenced to NaCl as the internal standard. This procedure covers a range of Sr isomorphic substitution of 0 to 12% SrSO4. Comparison with other values, derived from literature data, shows they are in good agreement with the experimental ones. Statistical analysis of the results yields a maximum absolute error of ±0.50 %SrSO4 in Sr determination. This measurement error proves to be acceptable for most studies of barite in mineral deposits. The effect of Pb-substitution is smaller, in most cases, than this error.The reported method has the advantage of being fast and simple. It can routinely handle large number of samples as well as small samples isolated from large crystals. Moreover, it allows the recovery of the original sample after the analysis by dissolving the NaCl in water. The main disadvantage is that fair amounts of quartz interfere with the measurement of the position of the barite 210 line.


2012 ◽  
Vol 26 ◽  
pp. 34-37 ◽  
Author(s):  
Adnan Mousharraf ◽  
Md Sazzad Hossain ◽  
Md Fakhrul Islam

The traditional white-ware manufacturing industries in Bangladesh use clay as the prime raw material which is mostly imported from abroad. The main reasons are the lack of proper clay refining technolo gy in the country and in some part the unsuitable chemical and structural composition of the locally available naturally occurring clays. Moreover, particle size has also been identified as a major challenge in processing of naturally available clay. These two vital aspects affect plasticity and strength of clay during their processing. The composition and particle size of locally available clay were investigated using X-Ray Fluorescence (XRF) and X-Ray Diffraction (XRD) to reveal the potential of these clays for industrial purpose upon refining. XRF analysis showed presence of excess SiO2 content in the form of Silicate, Fe2O3 and TiO2; all of which pose a challenge in the refining process. Moreover the amount of Al2O3 in most of the compositions is also not up to the minimum level. Using the data based on statistics on particle sizes of raw materials of various origins, this experiment was aimed to reveal the composition and properties of locally available clay that can be projected for further refining to make suitable as raw material for whiteware industries. DOI: http://dx.doi.org/10.3329/jce.v26i1.10179 JCE 2011; 26(1): 34-37


2021 ◽  
Vol 5 (2) ◽  
pp. 16
Author(s):  
Isabel Padilla ◽  
Maximina Romero ◽  
José I. Robla ◽  
Aurora López-Delgado

In this work, concentrated solar energy (CSE) was applied to an energy-intensive process such as the vitrification of waste with the aim of manufacturing glasses. Different types of waste were used as raw materials: a hazardous waste from the aluminum industry as aluminum source; two residues from the food industry (eggshell and mussel shell) and dolomite ore as calcium source; quartz sand was also employed as glass network former. The use of CSE allowed obtaining glasses in the SiO2-Al2O3-CaO system at exposure time as short as 15 min. The raw materials, their mixtures, and the resulting glasses were characterized by means of X-ray fluorescence, X-ray diffraction, and differential thermal analysis. The feasibility of combining a renewable energy, as solar energy and different waste for the manufacture of glasses, would highly contribute to circular economy and environmental sustainability.


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