A mineralogical characterization of biogenic calcium carbonates precipitated by heterotrophic bacteria isolated from cryophilic polar regions

Geobiology ◽  
2014 ◽  
Vol 12 (6) ◽  
pp. 542-556 ◽  
Author(s):  
J. Ronholm ◽  
D. Schumann ◽  
H. M. Sapers ◽  
M. Izawa ◽  
D. Applin ◽  
...  
Keyword(s):  
Heterotrophic Bacteria ◽  
Polar Regions ◽  
Mineralogical Characterization ◽  
Calcium Carbonates

scholarly journals Chemical and mineralogical characterization of portuguese ceramic tiles in the historic center of São Luís do Maranhão (Brazil): an approximation of the mineralogy and firing temperature of the raw materials

2013 ◽  
Vol 66 (1) ◽  
pp. 91-98 ◽  
Author(s):  
José Manuel Rivas Mercury ◽  
Domingos de Jesus Costa Pereira ◽  
Nazaré do Socorro Lemos Silva Vasconcelos ◽  
Aluísio Alves Cabral Jr. ◽  
Romulo Simões Angélica
Keyword(s):  
Firing Temperature ◽  
Raw Materials ◽  
X Ray Diffraction ◽  
Ceramic Tiles ◽  
Mineralogical Characterization ◽  
Calcium Carbonates ◽  
Historic Center ◽  
Mineral Phases ◽  
Materials Used

This work involved the first-ever characterization of antique Portuguese ceramic wall tiles in the Historic Center of São Luis do Maranhão, Brazil. The tiles were characterized by optical microscopy, X-ray diffraction (XRD) and chemical analysis to identify the possible raw materials used in the fabrication process, as well as the firing temperature of these materials. The results indicate that the microstructure of these materials consists of pores of varying sizes with calcite incrustations and quartz grain sizes smaller than 500 µm distributed in a pinkish yellow matrix, which were identified by XRD as calcite, gehlenite, wollastonite, quartz, and amorphous mineral phases. Based on this information, it can be inferred that the original raw materials probably consisted of a mixture of kaolinitic clays (Al2O3·2SiO2·2H2O) rich in calcium carbonates and quartz, or mixtures of kaolinitic clays, quartz and calcite, which did not reach the pre-firing temperature of 950ºC.

scholarly journals Flexural Strength and Crack Propagation of Porous Clay- Precipitated Calcium Carbonates

2017 ◽  
Author(s):  
NUR ALIA BINTI ROSLIN AZMY
Keyword(s):  
Flexural Strength ◽  
Raw Materials ◽  
Porous Ceramic ◽  
X Ray Diffraction ◽  
Red Clay ◽  
Mineralogical Characterization ◽  
Calcium Carbonates ◽  
Replication Method ◽  
Significant Difference

Porous clay-precipitated calcium carbonates were prepared via polymeric sponge replication method using precipitated calcium carbonates (PCC) and red clay as raw materials. Different compositions of precipitated calcium carbonates (PCC) which is 10 wt.% and 15 wt.% with 24 hours and 48 hours milling time were sintered at 1250°C for 2 hours respectively which influenced the flexural strength and morphology of the porous ceramic. The highest flexural strength (1.843 MPa) were obtained by 10 wt.% [CaCO3]PCC milled at 24 hours related to the lowest percentage of porosity (81.00%). Mineralogical characterization of porous ceramic were determined via X-ray diffraction (XRD) shows the presence of crystalline phases such as anorthite (2CaAl2Si2O8), gehlenite (Ca2Al2SiO7) and esseneite (CaFeAlSiO6) after sintering process. The morphological analysis via stereomicroscope shows that the porosity and struts were found due to presence of precipitated calcium carbonates that act as pore forming agent. The colour of porous ceramic between 10 wt.% [CaCO3]PCC and 15 wt.% [CaCO3]PCC shows significant difference due to iron oxide contained in the red clay which contributes to the colour of the samples. Crack propagates in the intergranular type of fracture mode due to resulted porous ceramic is a brittle material.

scholarly journals Assessment of Characteristics of Acid Mine Drainage Treated with Fly Ash

2021 ◽  
Vol 11 (9) ◽  
pp. 3910
Author(s):  
Saba Shirin ◽  
Aarif Jamal ◽  
Christina Emmanouil ◽  
Akhilesh Kumar Yadav
Keyword(s):  
Fly Ash ◽  
Acid Mine Drainage ◽  
Power Plants ◽  
Mine Drainage ◽  
Thermal Power ◽  
Mineralogical Characterization ◽  
Acid Mine ◽  
Before And After ◽  
Abandoned Coal Mines

Acid mine drainage (AMD) occurs naturally in abandoned coal mines, and it contains hazardous toxic elements in varying concentrations. In the present research, AMD samples collected from an abandoned mine were treated with fly ash samples from four thermal power plants in Singrauli Coalfield in the proximate area, at optimized concentrations. The AMD samples were analyzed for physicochemical parameters and metal content before and after fly ash treatment. Morphological, geochemical and mineralogical characterization of the fly ash was performed using SEM, XRF and XRD. This laboratory-scale investigation indicated that fly ash had appreciable neutralization potential, increasing AMD pH and decreasing elemental and sulfate concentrations. Therefore, fly ash may be effectively used for AMD neutralization, and its suitability for the management of coalfield AMD pits should be assessed further.

scholarly journals The Physico-Chemical and Mineralogical Characterization of Mg-Rich Synthetic Gypsum Produced in a Rare Earth Refining Plant

2021 ◽  
Vol 13 (9) ◽  
pp. 4840
Author(s):  
Fatai Arolu Ayanda ◽  
Mohd Firdaus Mohd Anuar ◽  
Syaharudin Zaibon ◽  
Shamshuddin Jusop
Keyword(s):  
Rare Earth ◽  
Acid Soils ◽  
Acid Neutralization ◽  
Mineralogical Characterization ◽  
X Ray ◽  
Neutralization Capacity ◽  
Acid Neutralization Capacity ◽  
Refining Plant ◽  
Calcium Magnesium

The physical, chemical and mineralogical characterization of the constituents of magnesium-rich synthetic gypsum produced in a rare earth-refining plant located in Gebeng, Pahang, Malaysia was conducted through elemental chemical analysis, scanning electron microscopy with Energy Dispersive X-ray (EDX)-analyzer, thermal analysis, X-ray fluorescence and X-ray diffraction. The crystalline nature of the by-product was studied using FTIR spectroscopy. Elemental analysis confirmed the presence of Ca and Mg, which are essential macronutrients required by plants and this Ca alongside the high pH (9.17) of MRSG may confer on the material a high acid neutralization capacity. From the result, it was observed that the studied by-product is a heterogeneous crystalline material comprising of gypsum (CaSO4.2H2O) and other major components such as calcium (magnesium) compounds (hydroxide, oxide, silicates, and carbonate) and sulfur. These aggregates may contribute to give an acid neutralization capacity to MRSG. The XRD study of MRSG indicated a high content of gypsum (45.4%), shown by the d-spacing of 7.609 Å (2-theta 11.63) in the diffractogram. The infrared absorption spectra of MRSG indicate close similarities to mined gypsum. The results of the characterization indicated that MRSG has valuable properties that can promote its use in amending soil fertility constraints on nutrient-deficient tropical acid soils.

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