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Calcite

Calcite is a naturally occurring calcium carbonate (CaCO3) mineral that is widely found in sedimentary rocks, such as limestone and marble.
It is a common and important mineral in many geological, biological, and industrial processes.
Calcite is known for its distinctive rhombohedral crystal structure and its ability to exhibit various optical properties, including birefringence and pleochroism.
Researchers studying calcite often focus on its formation, dissolution, and interactions with other chemical species, as well as its applications in fields like geology, paleontology, and materials science.
Understanding the properties and behaviors of calcite is crucial for a range of scientific endeavors, from understanding climate change to developing new construction materials.

Most cited protocols related to «Calcite»

1
Geothermal Microbial Community Analysis in Yellowstone
Cited 6 times
Five geothermal microbial communities in Yellowstone National Park (Figure 1) were sampled during summer-fall 2006 at the following research sites that have been subject to significant prior characterization: Crater Hills-Alice Spring (CH), Norris Geyser Basin- Beowulf Spring (NGB); Joseph's Coat Hot Springs-Scorodite Spring (JCHS); Mammoth Hot Springs-Narrow Gauge (MHS); Calcite Springs-Scary Spring (CS) [13] , [17] , [18] , [20] , [21] , [22] . The sites were chosen to represent a breadth of geochemical conditions and thermophilic phyla, and to focus exclusively on chemotrophic communities ranging in pH from 2.5 to 7.8 (Table 1). The location, physical and geochemical features of each sampling site (Table 1) are critical to understanding how organisms interface with geochemical processes. Microbial mat and or solid phase was sampled aseptically, placed on dry ice, and stored at −80°C until DNA extraction.
Inskeep W.P., Rusch D.B., Jay Z.J., Herrgard M.J., Kozubal M.A., Richardson T.H., Macur R.E., Hamamura N., Jennings R.D., Fouke B.W., Reysenbach A.L., Roberto F., Young M., Schwartz A., Boyd E.S., Badger J.H., Mathur E.J., Ortmann A.C., Bateson M., Geesey G, & Frazier M. (2010). Metagenomes from High-Temperature Chemotrophic Systems Reveal Geochemical Controls on Microbial Community Structure and Function. PLoS ONE, 5(3), e9773.
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Publication 2010
Calcite Dry Ice Fear Hot Springs Mammuthus Natural Springs Physical Examination scorodite
2
Modeling Viking Voyages to Greenland
Cited 5 times
To determine the success of a voyage from Bergen to Greenland, we defined the borderline near the coastline of Greenland from where the navigator could see the mountains of Greenland. The distance of this border from the coast was calculated as follows (electronic supplementary material, figure S37): (i) the average height of the mountains of Greenland is m = 1000 m; the first mountains are on average at distance c = 1000 m from the coast inside the island. A Viking observer could climb up on the mast of a Viking ship up to a height h = 21 m (above sea level) in order to see the mountains of Greenland as soon as possible. (ii) The radius of the Earth is r = 6372.8 km, and the Earth's shape was approximated by a sphere. (iii) The distance from where the top of the mountains can already be seen is d = r(α + β) − c, where α = arc cos[r/(r  +  m)] is the angular distance where the tangential straight line from the top of the mountain reaches the Earth's surface, and β = arc cos[r/(r + h)] is the angular distance measured from α where this tangential line reaches the observer at a height h on the ship's mast (electronic supplementary material, figure S37).
A voyage was considered as successful if the simulated sailing route crossed the borderline of visibility of the mountains of Greenland, otherwise it was unsuccessful. For a given sunstone crystal (calcite, cordierite and tourmaline), a given date (spring equinox and summer solstice) and a given navigation periodicity Δt (=1, 2, 3, 4, 5, 6 h) we simulated N = 1000 voyages, from which Ns was successful and Nu was unsuccessful (N = Ns + Nu). Finally, we computed the navigation success s = Ns/N in all 36 cases = 3 (sunstones) × 2 (dates) × 6 (navigation periodicities).
We also simulated reversed voyages from Hvarf (Greenland) to Norway along the 60°21′55″ N latitude. However, in these cases the voyages were always successful, because the simulated sailing routes always reached somewhere on the coasts of Europe.
Száz D, & Horváth G. (2018). Success of sky-polarimetric Viking navigation: revealing the chance Viking sailors could reach Greenland from Norway. Royal Society Open Science, 5(4), 172187.
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Publication 2018
Calcite cordierite Radius tourmaline Vision
3
Quantifying CaCO3 Accretion Rates and Calcification
Cited 5 times
To estimate site specific net CaCO3 accretion rates and to relate calcification/dissolution to natural variability in pH, the SeaFET sensors were co-located with Calcification/Accretion Units (CAUs) (Fig. S1). A CAU consisted of a pair of roughly sanded PVC plates (10×10 cm) stacked 1 cm apart and plate pairs (N = 5 per site) were affixed to reef pavement at each site (>0.5 m apart and 10 cm above the substrate) using stainless steel rods and marine epoxy. Immediately after collection, all four surfaces of each CAU were photographed to determine early-successional community structure using the image analysis software PhotoGrid 1.0 (25 stratified random points analyzed per surface); organisms were sorted into ecological functional groups to look for patterns structuring the communities on the benthos and on the CAUs. Plates were then preserved in 8% formalin for subsequent measures of calcification rates.
To quantify the mass of CaCO3 accumulated on a CAU, the plates were dried to a constant weight at 60°C and then weighed. Subsequently, CAUs were submerged in 5% HCl for 48 hrs or until all CaCO3 had dissolved. The remaining fleshy tissue was scraped onto pre-weighed 11 µm cellulose filter paper, vacuum filtered, dried, and weighed to determine the difference in calcified to fleshy biomass on CAU surfaces. Finally, the acidified, scraped, and dried CAU plates were weighed. Calcimass was determined by subtracting the weight of the fleshy tissue and PVC plates from the total mass of the CAU. For all taxa recruiting to CAUs, the polymorph of CaCO3 deposited is known. Thus, the relative net accretion for each polymorph (calcite, aragonite, high Mg calcite) was calculated by multiplying the net calcification rate by the relative abundance of each calcifying taxa of known mineralogy.
Price N.N., Martz T.R., Brainard R.E, & Smith J.E. (2012). Diel Variability in Seawater pH Relates to Calcification and Benthic Community Structure on Coral Reefs. PLoS ONE, 7(8), e43843.
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Publication 2012
Aragonite Calcinosis Calcite Carbonate, Calcium Cellulose Epoxy Resins Formalin Marines Neutrophil Rod Photoreceptors Stainless Steel Tissues Vacuum
4
Leucite Synthesis from Diatomite Precursor
Cited 4 times
The starting material was a diatomite, i.e. a tripolaceous siliceous rock (Tripoli rock) cropping out in the Crotone Basin in southern Italy. Tripoli was analysed by X-ray diffraction (XRPD) with a Siemens D5000 operating with a Bragg-Brentano geometry; CuKα = 1.518 Å, 40 kV, 40 mA, 2–35° scanning interval, step size 0.020° 2θ with a scan rate of 13 sec/step. Characterization of this material revealed a mineralogical assemblage mainly consisting of an amorphous siliceous fraction (diatoms and sponges, visible as the bulge in the range 17–25°2theta) with minor presences of quartz, montmorillonite, chlorite, kaolinite, K-micas and small amounts of calcite (Fig. 1). Chemical analysis of Tripoli rock is reported in Table 1 and was performed by X-ray fluorescence analysis (Axios-Max Advanced Panalytical; 60KV; 160 mA; 4000 W; 0.0001°2 θ). We considered the value of LOI of 1 g of sample obtained in ceramic meltpots running in an oxidizing furnace.

XRPD pattern of “Tripoli rock”.

Chemical composition of “Tripoli rock” analysed by X-ray fluorescence.

Tripoli rock
SiO281.07 (0.45)
TiO20.26 (0.02)
Al2O35.03 (0.02)
Fe2O32.14 (0.03)
MnO0.07 (0.01)
MgO1.11 (0.01)
CaO1.72 (0.03)
Na2O0.25 (0.02)
K2O0.68 (0.02)
P2O50.07 (0.01)
LOI7.73 (0.03)
Tot.100.13 (0.18)

The standard deviation values calculated for three analyses are reported in brackets. LOI: loss on ignition.

The synthesis of leucite was conducted through the mixing of silicate and aluminate solutions. These solutions were prepared according to the procedure already described in Novembre et al.24 (link) In the present study, 5.19 g of the ground and powdered Tripoli material were treated with HNO3 (65%), in order to dissolve the calcite fraction in order to remove the soluble calcite fraction from the starting material. The diatomitic sample (ca. 5 g after the HNO3 treatment) was added to 50 mL of KOH (6.8%). This solution was thoroughly mixed with a magnetic stirrer for 2 h and then put in a teflon reactor/bomb and heated in an oven at 80 °C for 24 h. After filtration, the remnant solid and insoluble fraction, which consisted of clay minerals and quartz, was separated from the silicate solution. The resulting molar composition of the solution was 0.060 K2O–0.026SiO2–0.625H2O with traces as follows: 2.01 ppm Mg, 2.11 ppm Ca and Al, Ti and Mn lower than 0.1 ppm. Based on a mass balance calculation following this step-wise chemical separation process, the Tripoli rock was determined to be composed of: 63.27 wt% amorphous silica (diatoms and sponges), 32 wt% of clay minerals and quartz, and 3.83 wt% calcite.
The aluminate solution was prepared as follows: 0.45 g of Al(OH)3 (65%) was mixed with 50 mL of KOH (6.8%). The obtained aluminous solution with a composition of 0.060 K2O–0.0076Al2O3–0.625 H2O (Mn, Ti and Mg < 0.01 ppm; Fe < 0.4 ppm; K, Ca and Si < 0.2 ppm) was then heated at 100 °C for one hour.
A series of three syntheses were carried out by varying the volume ratio of the two solutions according to Table 2.

Starting mixture and relative obtained mineralogical assemblages of experimental runs.

synthesis runstarting mixtureSiO2/Al2O3mineralogical assemblage
110 ml siliceous sol + 10 ml aluminous sol3.40KAlSi2O6 + KAlSIO4-O1 (1.5–20 h); KAlSi2O6 (24 h)
212.5 ml siliceous sol + 7.5 ml aluminous sol5.70KAlSi2O6 + KAlSIO4-O1 (1.5–15 h); KAlSi2O6 (20 h)
310 ml siliceous sol + 5 ml aluminous sol6.80KAlSi2O6 + KAlSIO4-O1 (3 h); KAlSi2O6 (15–20 h)
The reactants were vigorously mixed for two hours with a magnetic stirrer. Each mixture was heated inside an autoclave at 150 °C and ambient pressure for a duration of one hour. The hydrothermally derived gel precursors were recovered from the reactors, filtered from the solution, thoroughly washed with distilled water and dried in an oven at 40 °C for 24 hours. These gel products were examined by XRPD analysis (Fig. 2) in order to assess their amorphous character. The three gel precursors were then calcined at 1000 °C with periodic sampling carried out at scheduled intervals.

XRPD patterns of the hydrothermal gel precursors. (a): synthesis run 1; (b): synthesis run 2; (c) synthesis run 3.

All intermediate and final products of the three syntheses were analysed by XRPD under the same operating conditions as those for the “Tripoli rock” analysis. Identification of phases and relative peak assignment were made with reference to the following JCPDS codes: 00-038-1423 for leucite and 00-011-0579 for KAlSIO4-O1. The amounts of both the crystalline and amorphous phases in the synthesis powders were estimated using Quantitative Phase Analysis (QPA) applying the combined Rietveld and Reference Intensity Ratio (RIR) methods; corundum NIST 676a was added to each sample, amounting to 10%, and the powder mixtures were homogenized by hand-grinding in an agate mortar. Data for the QPA refinement were collected in the angular range 5–70° 2θ with steps of 0.02° 2θ and 10 s step−1, a divergence slit of 0.5° and a receiving slit of 0.1 mm.
Data were processed with the GSAS software28 and the graphical interface EXPGUI29 (link). The unit cell parameters were determined, starting with the structural models proposed by Dove et al.30 for leucite and Kremenovic et al.31 (link) for KAlSiO4-O1. Parameters were refined following Novembre et al.25 (link).
Analysis of synthesized powders was performed by inductively coupled plasma optical emission spectroscopy (ICP-OES, Perkin Elmer Optima 3200 RL) after alkaline fusion of the sample in a Pt crucible (lithium meta-tetra borate pearls, at 3/2 ratio) and subsequent acid solubilization27 (link).
Scanning electron microscope (SEM) analyses were carried out with a JEOL JSM-840 with operating conditions of 15 kV and window conditions ranging from 18 to 22 mm, following the procedure as explained in Ruggieri et al.32 (link).
Vibrational spectra of the synthesized products were obtained with an Infrared spectrometer FTLA2000, equipped with SiC (Globar) filament source, KBr beamsplitter and DTGS detector. Samples were prepared according to the method of Robert et al.33 (link) using powder pressed pellets (sample/KBr ratio of 1:100); spectra were processed with the program GRAMS-Al.
Thermal behaviour of gel precursors were studied by differential thermal analysis and thermogravimetry (DTA-TG) by means of a Mettler TGA/SDTA851e instrument (10°/minute from 30° to 1100 °C, using an approximate sample weight of 10 mg in Al2O3 crucible).
Density of leucite was measured by He-picnometry using an AccuPyc 1330 pycnometer.
Novembre D., Gimeno D, & Poe B. (2019). Synthesis and Characterization of Leucite Using a Diatomite Precursor. Scientific Reports, 9, 10051.
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Publication 2019
Acids Anabolism Calcite Cells Character Chemical Processes chlorite Clay Columbidae Corundum Cytoskeletal Filaments diatomite Diatoms Differential Thermal Analysis dolutegravir Filtration Fluorescence Kaolinite leucite lithium borate mica Minerals Molar Montmorrillonite Pellets, Drug Plasma Porifera Powder Pressure Quartz Radionuclide Imaging Roentgen Rays Scanning Electron Microscopy Silicates Silicon Dioxide SLIT1 protein, human Spectrum Analysis Teflon Tetragonopterus Thermogravimetry Vibration Vision X-Ray Diffraction
5
Acid-Activated Montmorillonite for Environmental Remediation
Cited 4 times

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Publication 2019
acetonitrile Acids Anabolism Aroclors Buffers Calcite Carbon Charcoal, Activated Clay Coconut feldspar Filtration Food Generic Drugs Gifts Heartburn High-Performance Liquid Chromatographies Ions Metals mica Montmorrillonite Organic Chemicals orthoclase Parent Quartz sanidine Spectroscopy, Fourier Transform Infrared Sulfuric Acids

Most recents protocols related to «Calcite»

1
Enhancing Chalcopyrite Leaching with Thiourea
Not available on PMC !

Example 1

The effect of Tu on the electrochemical behavior of a chalcopyrite electrode was studied in a conventional 3-electrode glass-jacketed cell. A CuFeS2 electrode was using as working electrode, a saturated calomel electrode (SCE) was used as reference, and a graphite bar was used as counter-electrode. The CuFeS2 electrode was polished using 600 and 1200 grit carbide paper. All experiments were conducted at 25° C. using a controlled temperature water bath. The electrolyte composition was 500 mM H2SO4, 20 mM Fe2SO4 and 0-100 mM Tu. Before starting any measurement, solutions were bubbled with N2 for 30 minutes to reduce the concentration of dissolved 02. Open circuit potential (OCP) was recorded until changes of no more than 0.1 mV/min were observed. After a steady OCP value was observed, electrochemical impedance spectroscopy (EIS) was conducted at OCP using a 5 mV a.c. sinusoidal perturbation from 10 kHz to 10 mHz. Linear polarization resistance (LPR) tests were also conducted using a scan rate of 0.05 mV/s at ±15 mV from OCP.

Linear potential scans were conducted at electrode potentials ±15 mV from the OCP measured at each Tu concentration. All scans showed a linear behavior within the electrode potential range analyzed. An increase in the slope of the experimental plots was observed with increasing Tu concentration. The slope of these curves was used to estimate the value of the polarization resistance (Ret) at each concentration. These values were then used to estimate the values of the dissolution current density using equation 1:

i dissol ≈ RT nFR ct Eq . ⁢ ( 1 )

FIG. 3 shows the effect of Tu on the dissolution current density and mixed potential of the CuFeS2 electrode, and indicates that a maximum dissolution current density was achieved when Tu concentration is 30 mM. Increasing Tu concentration to 100 mM resulted in a decrease in the current density and mixed potential of the CuFeS2 electrode. Moreover, after immersing the CuFeS2 electrode in the 100 mM Tu solution, a copper-like film was observed on the surface of the electrode, which film could only be removed by polishing the electrode with carbide paper.

FIG. 4 is a bar graph showing the effect of initial Tu or FDS concentration on the electrochemical dissolution of a chalcopyrite electrode in sulfuric acid solution at pH 2 and 25° C. A concentration of 10 mM Tu in the leach solution resulted in a six fold increase in dissolution rate compared to no Tu, and a concentration of 5 mM FDS resulted in a six fold increase relative to 10 mM Tu. A concentration of 10 mM Tu in leach solution also containing 40 mM Fe(III) resulted in a thirty fold increase in dissolution rate compared to 40 mM Fe(III) alone.

A column leach of different acid-cured copper ores was conducted with Tu added to the leach solution. A schematic description of the column setup is shown in FIG. 5. The column diameter was 8.84 cm, the column height was 21.6 cm, and the column stack height was 15.9 cm. The irrigation rate was 0.77 mL/min or 8 L/m2/h. The pregnant leach solution emitted from these columns was sampled for copper every 2 or 3 days using Atomic Absorption Spectroscopy (AAS).

The specific mineralogical composition of these ores are provided in Table 1. The Cu contents of Ore A, Ore B, and Ore C were 0.52%, 1.03%, and 1.22% w/w, respectively. Prior to leaching, ore was “acid cured” to neutralize the acid-consuming material present in the ore.

That is, the ore was mixed with a concentrated sulfuric acid solution composed of 80% concentrated sulfuric acid and 20% de-ionized water and allowed to sit for 72 hours. For one treatment using Ore C, Tu was added to the sulfuric acid curing solutions.

The initial composition of the leaching solutions included 2.2 g/L Fe (i.e. 40 mM, provided as ferric sulfate) and pH 2 for the control experiment, with or without 0.76 g/L Tu (i.e. 10 mM). The initial load of mineral in each column was 1.6 to 1.8 kg of ore. The superficial velocity of solution through the ore column was 7.4 L m−2 h−1. The pH was adjusted using diluted sulfuric acid. These two columns were maintained in an open-loop or open cycle configuration (i.e. no solution recycle) for the entire leaching period.

The results of leaching tests on the Ore A, Ore B and Ore C are shown in FIGS. 6, 7, and 8, respectively. The presence of Tu in the lixiviant clearly has a positive effect on the leaching of copper from the chalcopyrite. On average, the leaching rate in the presence of Tu was increased by a factor of 1.5 to 2.4 compared to the control tests in which the leach solutions did not contain Tu. As of the last time points depicted in FIGS. 6 to 8, copper extractions for columns containing Ore A, Ore B, and Ore C leached with a solution containing sulfuric acid and ferric sulfate alone, without added Tu, were 21.2% (after 198 days), 12.4% (after 50 days), and 40.6% (after 322 days), respectively. With 10 mM of added Tu, these extractions were 37.9%, 32.0%, and 72.3%, respectively.

Referring to FIG. 8, 2 mM Tu was added to the leach solution originally containing no Tu from day 322 onward, after which the leach rate increased sharply. From day 332 to day 448, the copper leached from this column increased from 40% to 58%, and rapid leaching was maintained throughout that period.

The averages for the last 7 days reported in FIG. 9 indicate that the leaching rate for acid-cured Ore C leached in the presence of 10 mM Tu is 3.3 times higher than for acid-cured Ore C leached in the absence of Tu, and 4.0 times higher than acid-cured and Tu-cured Ore C leached in the absence of Tu.

FIG. 10 shows the effect of Tu on solution potential. All potentials are reported against a Ag/AgCl (saturated) reference electrode. The solution potential of the leach solutions containing Tu was generally between 75 and 100 mV lower than the solution potential of leach solution that did not include Tu. Lower solution potentials are consistent with Tu working to prevent the passivation of chalcopyrite.

“Bottle roll” leaching experiments in the presence of various concentrations of Tu were conducted for coarse Ore A and Ore B. The tests were conducted using coarsely crushed (100% passing ½ inch) ore.

Prior to leaching, the ore was cured using a procedure similar to what was performed on the ore used in the column leaching experiments. The ore was mixed with a concentrated sulfuric acid solution composed of 80% concentrated sulfuric acid and 20% de-ionized water and allowed to settle for 72 hours to neutralize the acid-consuming material present in the ore. For several experiments, different concentrations of Tu were added to the ore using the sulfuric acid curing solutions.

The bottles used for the experiments were 20 cm long and 12.5 cm in diameter. Each bottle was loaded with 180 g of cured ore and 420 g of leaching solution, filling up to around one third of the bottle's volume.

The leaching solution from each bottle was sampled at 2, 4, 6 and 8 hours, and then every 24 hours thereafter. Samples were analyzed using atomic absorption spectroscopy (AAS) for their copper content.

The conditions for the bottle roll experiments are listed in Table 2. Experiments #1 to #6 were conducted using only the original addition of Tu into the bottles. For experiments #7 to #11, Tu was added every 24 hours to re-establish the Tu concentration.

A positive effect of Tu on copper leaching was observed. For the coarse ore experiments, a plateau was not observed until after 80 to 120 hours. Tu was added periodically to the coarse ore experiments, yielding positive results on copper dissolution.

The effect of different concentrations of Tu in the leach solution on the leaching of coarse ore (experiments #1 to #11 as described in Table 2) is shown in FIGS. 11 and 10.

For ore B, Tu was periodically added every 24 hours to re-establish the thioruea concentration in the system and thus better emulate the conditions in the column leach experiments. As may be observed from FIG. 9, 8 mM and 10 mM Tu yielded higher copper dissolution results than the other Tu concentrations tested for ore A. A plateau in dissolution is not observed until after approximately 120 hours, which varied with Tu concentration as shown in FIG. 11.

TABLE 1
MineralIdeal FormulaOre AOre BOre C
ActinoliteCa2(Mg,Fe2+)5Si8O22(OH)2—1.8—
BiotiteK(Mg,Fe2+)3AlSi3O10(OH)2—4.2—
CalciteCaCO3—19.3 —
ChalcopyriteCuFeS2 1.43.52.6
Clinochlore(Mg,Fe2+)5Al(Si3Al)O10(OH)8—15.0 —
DiopsideCaMgSi2O6—3.5—
GalenaPbS——0.1
GypsumCaSO42H2O—1.2—
Hematiteα-Fe2O3—0.2—
K-feldsparKAlSi3O817.910.8 —
KaoliniteAl2Si2O5(OH)4 2.3—2.3
MagnetiteFe3O4—0.8—
MolybdeniteMoS2<0.1——
MuscoviteKAl2AlSi3O10(OH)221.96.041.6 
PlagioclaseNaAlSi3O8—CaAlSi2O813.625.4 —
PyriteFeS2 2.3—8.0
QuartzSiO240.08.344.4 
RutileTiO2 0.5—0.9
SideriteFe2+CO3—0.1—
Total100  100  100  

As may be observed from FIG. 12, 5 mM Tu yielded higher copper dissolution results than the other Tu concentrations tested for ore B. As with ore A, a plateau in dissolution is not observed until after approximately 80 to 120 hours, which varied with Tu concentration as shown in FIG. 12. Periodic addition of Tu resulted in increased copper dissolutions and produced a delay in the dissolution plateau.

Interestingly, solutions containing 100 mM Tu did not appear to be much more effective on copper extraction than those containing no Tu, and even worse at some time points. This is consistent with the results of Deschenes and Ghali, which reported that solutions containing 200 mM Tu (i.e. 15 g/L) did not improve copper extraction from chalcopyrite. Tu is less stable at high concentrations and decomposes. Accordingly, it is possible that, when initial Tu concentrations are somewhat higher than 30 mM, sufficient elemental sulfur may be produced by decomposition of Tu to form a film on the chalcopyrite mineral and thereby assist in its passivation. It is also possible that, at high Tu dosages, some copper precipitates from solution (e.g. see FIG. 17) to account for some of the low extraction results.

US11859263B2. Process for leaching metal sulfides with reagents having thiocarbonyl functional groups (2024-01-02). Jetti Resources, LLC [US]. Inventors: David Dixon [CA], Edouard Asselin [CA], Zihe Ren [CA], Nelson Mora Huertas [US].
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Patent 2024
Acids actinolite Bath biotite Calcite calomel Carbonate, Calcium Cells chalcopyrite Chemoradiotherapy Copper Dielectric Spectroscopy diopside Electrolytes factor A feldspar ferric sulfate ferrous disulfide galena Graphite Gypsum hematite Kaolinite Magnetite Minerals muscovite Oxide, Ferrosoferric plagioclase Quartz Radionuclide Imaging Recycling rutile siderite Sinusoidal Beds Spectrophotometry, Atomic Absorption Suby's G solution Sulfur sulfuric acid TU-100
2
Calcium Carbonate Coated Synthetic Fibers
Not available on PMC !

Example 1

In this example, calcium carbonate crystallization (CaCO3) is used to deposit calcium carbonate on synthetic fibers. Calcium carbonate crystals were formed by mixing a CaCl2) solution and a NaCO3 solution and adding the mixture to a suspension of BAROLIFT® fibers. The resulting precipitated calcium carbonate on the fibers was in the form of discrete calcite crystals that were sparsely distributed about the outer surface of the fibers.

The shear thinning behavior of the resulting fiber additives was tested against that of untreated BAROLIFT® fibers. Both types of fibers were added to BARAZAN® D PLUS™ (viscosifier/suspension agent, available from Halliburton Energy Services, Inc.) in a concentration of 1.2 wt. %, and the shear viscosity for each solution was tested at different shear rates. The viscosity profile was obtained using a coaxial cylinder geometry (bob-cup) on an MCR501 rheometer (available from Anton Paar). FIG. 2 is a plot 200 illustrating the shear viscosity 202 in pascal seconds (Pa·s) of each of the tested fluids taken as a function of shear rate (1/seconds) 204. A first trace 206 represents the measurements taken for the solution with untreated fibers, while a second trace 208 represents the measurements taken for the solution with the treated fibers (fibers with calcium carbonate grown thereon). As illustrated, the shear viscosity for the treated fibers 208 is higher than that for the untreated fibers 206 across a wide range of shear rates. These results indicate that the fiber additives with calcium carbonate coated thereon experience increased interactions between the fibers, thereby improving the shear thinning behavior of the suspension by preventing fiber alignment in shear.

Example 2

In this example, calcium carbonate crystallization (CaCO3) is used to deposit calcium carbonate on synthetic fibers after an acid treatment is performed on the fibers. The acid treatment increases the population of calcium carbonate crystals formed on the outer surface of the fibers. A suspension of BAROLIFT® fibers was treated with 1M NaOH solution for 2 hours. Then, calcium carbonate crystals were formed on the fiber surface by mixing a CaCl2 solution and a NaCO3 solution and adding the mixture to the fibers. The resulting precipitated calcium carbonate on the fibers was in the form of discrete calcite crystals that were more concentrated on the outer surface of the fibers, as compared to the fiber additives of Example 1.

US11859478B2. Calcium carbonate / fiber additives for use in subterranean operations (2024-01-02). Halliburton Energy Services, Inc. [US]. Inventors: Xiangnan Ye [US], Dale E. Jamison [US].
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Patent 2024
Acids A Fibers Calcite Carbonate, Calcium Crystallization Fibrosis Viscosity
3
Aragonite and Calcite Crystallography in Coral
The surface sample (of thick slides) was polished with alumina of 1 µm, 0.3 µm, and 0.05 µm and finally polished with colloidal silica (0.05 µm). Before analysis, samples were coated with a thin layer (ca. 2 nm) of carbon using a high vacuum coater. The EBSD study was carried out with Oxford NordlysMax detector mounted on a scanning electron microscope JEOL JSM-6610LV at the Institute of Materials Engineering, Łódź University of Technology. EBSD data were collected with AztecHKL software at high vacuum, 20 kV, large probe current, and 20 mm of working distance. EBSD patterns were collected at a resolution of 0.22 μm step size for crystallographic maps using the unit cell settings characteristic of aragonite and calcite as follows58 (link),59 (link): “Pmcn” symmetry and a = 4.96 Å, b = 7.97 Å, and c = 5.75 Å estimated for Favia coral using X-ray powder diffraction with synchrotron radiation (43) and a = b = 4.99 Å, and c = 17.06 Å, respectively. The EBSD data are represented in this study by crystallographic maps, phase images, and the pole figures, which represent the stereographic projection of crystallographic planes in reference to the (100), (010), (001) and (222) aragonite planes. Orientation images and the pole figures were created using MTEX open source plugin for Matlab program (https://mtex-toolbox.github.io/). To eliminate combination of red and green colors and create images more accessible for color-blind users we selected BungeColorKey palette from MTEX (the outcome was tested using Coblis, the Color Blindness Simulator at https://www.color-blindness.com/coblis-color-blindness-simulator/).
Stolarski J., Drake J., Coronado I., Vieira A.R., Radwańska U., Heath-Heckman E.A., Mazur M., Guo J, & Meibom A. (2023). First paleoproteome study of fossil fish otoliths and the pristine preservation of the biomineral crystal host. Scientific Reports, 13, 3822.
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Publication 2023
Aragonite Blindness, Color Calcite Carbon Cells Coral Crystallography Microtubule-Associated Proteins Oxide, Aluminum Powder Radiation Scanning Electron Microscopy Silicon Dioxide Vacuum X-Ray Diffraction
4
Crystallization Kinetics of Ce-Bearing Solids
Two types of experimental methods were set up: (1) solution experiments and (2) replacement experiments. The combination of these two experimental settings and the studied temperature ranges allowed us to gain an in-depth picture on the kinetics and the governing factors during the crystallisation of Ce-bearing solids in the Ce–CO3–H2O system and provide detailed description for future material fabrication.
In the solution experiments, 10 ml of 50 mM Ce-bearing aqueous (Milli-Q) solutions (pH ≈ 5.1) were added to 10 ml of 50 mM Na2CO3 solutions in 20 ml Teflon-lined stainless-steel autoclaves at different temperatures (35, 50, 80 °C) and at saturated water vapor pressures (Table 1). To get more insight into the interaction of Ce and carbonate ions and the effects of temperature and concentration, additional 10 ml Ce-bearing aqueous (Milli-Q) solution (pH ≈ 5.1) mixed with 10 ml of Na2CO3 solution experiments were pre-heated and placed in hydrothermal reactors at 80 °C with different molar ratios of 1 : 1, 3 : 4 and 1 : 2 (Table 1). The solid samples were taken carefully at increasing time intervals. The reaction products were chilled to room temperature and filtered through 0.2 μm polycarbonate membranes by using a vacuum filtration unit. The solids were then placed into an oven at 50 °C for 30 min to remove any excess water.
In the replacement setting, 0.1 g of calcite, dolomite, or aragonite with sizes of 0.5–1.0 mm were added to 50 ml of 50 mM Ce-bearing aqueous (Milli-Q) solutions (Ce(NO3)3·6H2O; pH ≈ 5.1). The solutions each were prepared using cerium(iii) nitrate hexahydrate (Ce(NO3)3·6H2O) reagents (Sigma-Aldrich; 99.99% trace metals basis). The solutions and solids were placed in 50 ml Teflon-lined stainless-steel autoclaves at different temperatures (50, 90, 165, and 205 °C) and saturated water vapor pressures (Tables 2 and 3). Solid samples were taken carefully at increasing time intervals which were then placed into an oven at 50 °C for 30 min to remove any excess water. Also, control experiments consisting only of Ce-bearing aqueous solutions in closed reactors were carried out at the same temperatures of the solution and replacement experiments.
Szucs A.M., Maddin M., Brien D., Rateau R, & Rodriguez-Blanco J.D. (2023). The role of nanocerianite (CeO2) in the stability of Ce carbonates at low-hydrothermal conditions. RSC Advances, 13(10), 6919-6935.
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Publication 2023
Aragonite Calcite Carbonates Cerium Crystallization dolomite Filtration Hydrostatic Pressure Ions Metals Molar Nitrates polycarbonate Stainless Steel Teflon Tissue, Membrane Vacuum
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Characterising Mineral Transformations via SEM
Scanning electron microscopy (SEM) was used to characterise the precipitates from the solution experiments, the changes in the morphology of the host minerals (calcite, dolomite, or aragonite), and the newly formed crystalline phases. Samples from the replacement experiments were carbon-coated and placed into a Tescan MIRA4 S8000 FEG-SEM operating under high-vacuum conditions and equipped with four Oxford Instruments NanoAnalysis X-Max 170 mm2 EDS detector running Oxford Instruments NanoAnalysis AZtecTimed analysis software. Powders from solution experiments were Au–Pd coated and imaged with Tescan TIGER MIRA3 FEG-SEM equipped with two Oxford Instruments X-Max 150 mm2 EDS detectors running Oxford Instruments AZtec software. All analyses were performed using an accelerating voltage of either 5 or 10 kV for detailed imaging.
Szucs A.M., Maddin M., Brien D., Rateau R, & Rodriguez-Blanco J.D. (2023). The role of nanocerianite (CeO2) in the stability of Ce carbonates at low-hydrothermal conditions. RSC Advances, 13(10), 6919-6935.
Full text: Click here
Publication 2023
Aragonite Calcite Carbon dolomite Ehlers-Danlos Syndrome with Platelet Dysfunction from Fibronectin Abnormality Minerals Powder Scanning Electron Microscopy Tigers Vacuum

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More about "Calcite"

Calcite, the ubiquitous calcium carbonate (CaCO3) mineral, is a fascinating subject of study across various scientific disciplines.
This naturally occurring crystalline form is a prevalent component in sedimentary rocks like limestone and marble, playing a crucial role in geological, biological, and industrial processes.
Researchers investigating calcite often focus on its formation, dissolution, and interactions with other chemical species.
Understanding the distinctive rhombohedral crystal structure and optical properties, such as birefringence and pleochroism, is central to these inquiries.
Calcite's versatility is showcased in its applications in fields like geology, paleontology, and materials science, where it is vital for endeavors ranging from climate change research to the development of innovative construction materials.
Analytical techniques like GTH 10M-A, Avaspec-3648, GasBench II, D/MAX-2200, Eclipse 80i, and Nicolet iS5 spectrometer are frequently employed to study the chemical and physical characteristics of calcite.
Additionally, the use of CaCl2 and MAT 253 instruments provides valuable insights into the compound's behavior and interactions.
Enhancing the reproducibility and accuracy of calcite research is crucial, and platforms like PubCompare.ai offer AI-powered solutions to streamline the process.
These tools enable users to seamlessly locate the best protocols from literature, preprints, and patents, ultimately elevating the quality and impact of calcite studies.