The influence of morphology of ultra-fine calcite particles on decomposition kinetics

Ren, Yuanlong; Wang, X.; Shui, Miao; Li, R. S.

doi:10.1007/s10973-007-8610-x

Cited by 5 publications

(3 citation statements)

References 13 publications

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“…Similar type of JMA kinetics was observed by Courtade et al for the growth of NiO from Ni films [33]. As in our case, change in kinetics with lattice strain was recently reported for decomposition of ultrafine calcite by Ren et al [34]. Arrhenius plot using Kissinger equation Fig.…”

Section: Master Plot Methods To Study Kineticssupporting

confidence: 89%

Oxidation kinetics of nickel nano crystallites obtained by controlled thermolysis of diaquabis(ethylenediamine)nickel(II) nitrate

Robinson

Arun

Manju

et al. 2009

J Therm Anal Calorim

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The metal complex, [Ni(en) 2 (H 2 O) 2 ](NO 3 ) 2 (en = ethylenediamine), was decomposed in a static furnace at 200°C by autogenous decomposition to obtain phase pure metallic nickel nanocrystallites. The nickel metal thus obtained was studied by XRD, IR spectra, SEM and CHN analysis. The nickel crystallites are in the nanometer range as indicated by XRD studies. The IR spectral studies and CHN analyses show that the surface is covered with a nitrogen containing species. Thermogravimetric mass gain shows that the product purity is high (93%). The formed nickel is stable and resistant to oxidation up to 350°C probably due to the coverage of nitrogen containing species. Activation energy for the oxidation of the prepared nickel nanocrystallites was determined by non-isothermal methods and was found to depend on the conversion ratio. The oxidation kinetics of the nickel crystallites obeyed a Johnson-Mehl-Avrami mechanism probably due to the special morphology and crystallite strain present on the metal.

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Section: Master Plot Methods To Study Kineticssupporting

confidence: 89%

Oxidation kinetics of nickel nano crystallites obtained by controlled thermolysis of diaquabis(ethylenediamine)nickel(II) nitrate

Robinson

Arun

Manju

et al. 2009

J Therm Anal Calorim

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show abstract

“…Despite their physico‐chemical inhomogeneities, calcite decomposition takes place, in the four samples, with very similar α versus time behavior in the isothermal runs, suggesting a common driving mechanism. In particular, calcite decomposition happens in a single step, leading to a cubic‐shaped and well crystallized CaO, without an intermediate step (a metastable CaO with a rhombohedral structure was observed in other experiments). The geometrical contraction reaction model (R3) gives a good fit with the experimental results.…”

Section: Discussionmentioning

confidence: 99%

A Kinetic Study of Thermal Decomposition of Limestone UsingIn SituHigh TemperatureX‐Ray Powder Diffraction

et al. 2012

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The kinetics of the thermal decomposition of a limestone and, simultaneously, of the lime growth have been investigated during isothermal treatments by means of in situ High Temperature X‐Ray Powder Diffraction. In particular, four grain sizes of a quarry limestone with differences in terms of mineralogical composition (dolomite content), chemical composition (Fe and Mg amounts), and texture, have been studied. The lime produced during the isothermal treatments was then examined by using Scanning Electron Microscopy. In all samples, limestone decomposition starts with dolomite dissociation, followed by calcite decomposition. Rather than particle size, limestone texture, and dolomite content seem to be the most important factors controlling the starting temperature of calcination and its kinetic behavior.

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“…Pure limestone or calcite is calcinated in a kiln at 1000 °C to produce calcium oxide for aluminothermic reduction. The thermal decomposition of calcite has been the subject of extensive research over the last 50 years [5][6][7][8][9][10][11]. Hills [6] investigated the calcium carbonate decomposition, and showed that the decomposition reaction takes place on a definite boundary between the undecomposed carbonate, and the layer of porous lime formed outside it.…”

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confidence: 99%

The possibilities of obtaining metallic calcium from Serbian carbonate mineral raw materials

Sokić

Matković

Marković

et al. 2014

CI&CEQ

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Article Highlights• Defined technological scheme of the calcium production from Serbian limestones • The influence of operating parameters on CaCO 3 calcination was examined • The dissociation is completed in 15 min at 1200 °C • The satisfactory rate for CaO aluminothermic reduction is accomplished at 1200 °C in 2 h • The content of hardly evaporated metals in obtained Ca is very low AbstractWe present experimental investigations that define both the technological scheme of calcium production from limestone by aluminothermic process and the basic operating parameters of the particular technological phases. The limestone with high content of Mg, Na and K was used in the study. X-ray analysis reveals that the samples contain mainly calcite with small amount of dolomite. At first, the effects of temperature, time and granulometry on the calcium carbonate calcination were examined. The dissociation process was completed in 10-15 min at 1200 °C, and the dissociation rate increased with decreasing particle size down to 5 mm. Afterwards, the aluminothermic reduction process of calcium oxide was investigated. At a temperature of 1200 °C and vacuum of at least 3 kPa, the reduction process completed within 2 h. The chemical composition of calcium oxide and calcium showed increased content of magnesium oxide and alkaline oxides (especially sodium).Pure calcium is a bright silvery-white metal, extremely soft and ductile. The metal oxidizes rapidly in the presence of moisture or in a dry air at temperature above 300 °C [1,2]. Calcium reacts readily with water, forming hydrated lime (calcium hydroxide) and hydrogen. It melts at 845 °C, boils at 1420 °C, and can be purified by distillation in an inert atmosphere or in a vacuum.Owing to its chemical reactivity with oxygen, calcium never occurs naturally in the free state although the compounds of the element are widely distributed among geological materials. The main calcium-bearing minerals are: the three carbonates -calcite, ara-

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The influence of morphology of ultra-fine calcite particles on decomposition kinetics

Cited by 5 publications

References 13 publications

Oxidation kinetics of nickel nano crystallites obtained by controlled thermolysis of diaquabis(ethylenediamine)nickel(II) nitrate

Oxidation kinetics of nickel nano crystallites obtained by controlled thermolysis of diaquabis(ethylenediamine)nickel(II) nitrate

A Kinetic Study of Thermal Decomposition of Limestone UsingIn SituHigh TemperatureX‐Ray Powder Diffraction

The possibilities of obtaining metallic calcium from Serbian carbonate mineral raw materials

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