Calciothermal reduction of tantalate iron and manganese

2021 ◽  
Vol 10 ◽  
pp. 56-64
Author(s):  
R. I. Gulyaeva ◽  
◽  
S. V. Sergeeva ◽  
S. A. Petrova ◽  
L. Yu. Udoeva ◽  
...  
Keyword(s):  
Equilibrium Constants ◽  
Tantalum Oxide ◽  
Structural Type ◽  
Experimental Investigations ◽  
Isothermal Heating ◽  
Main Metal ◽  
Argon Flow ◽  
Reduction Of Iron ◽  
Iron And Manganese ◽  
Metallic Calcium

Processes of calciothermal reduction of metals from iron (FeTa2O6) and manganese (MnTa2O6) tantalates as well as tantalum oxide (Ta2O5) were studied in this work. According to the results of thermodynamic analysis performed in the temperature range 373 – 2773 К, the interaction of FeTa2O6 and MnTa2O6 with calcium proceeds with complete reduction of metals. By the calculation and comparison of the lgK equilibrium constants for the reactions of alumino- and calciothermal reduction of iron and manganese tantalates were showed the thermodynamic advantage of using metallic calcium as a reducing agent. Experimental investigations of calciothermal reduction on samples of synthesized oxides were carried out by the method of combined thermogravimetry and differential thermal analysis in the mode of non-isothermal heating to 1473 K in an argon flow. X-ray powder diffraction was used to determine the phase composition of the initial samples and interaction products. It was shown that the calciothermal reduction of metals from the synthesized manganese tantalate proceeds actively at temperatures above 1196 K, while iron tantalate and tantalum oxide with the appearance of molten calcium. Tantalum and its solid solutions with iron or manganese, corresponding to the structural type Ta7Fe6, were included in the main metal components of the products of the interaction of FeTa2O6 and MnTa2O6 with calcium.

The aqueous chemistry of tellurium: critically-selected equilibrium constants for the low-molecular-weight inorganic species

2019 ◽  
Vol 16 (4) ◽  
pp. 289 ◽  
Author(s):  
Montserrat Filella ◽  
Peter M. May
Keyword(s):  
Molecular Weight ◽  
Aqueous Solutions ◽  
Thermodynamic Data ◽  
Equilibrium Constants ◽  
Computer Programs ◽  
Experimental Investigations ◽  
Low Molecular Weight ◽  
Aqueous Chemistry ◽  
Scientific Disciplines ◽  
Inorganic Species

Environmental contextEquilibrium constants are required in many scientific disciplines such as biology, medicine, engineering, and in particular chemistry. Lack of reliable equilibrium constants for tellurium has restricted our understanding of its speciation and behaviour in the environment. This study presents a reliable set of equilibrium constants for tellurium, thereby providing a more coherent basis for future experimental investigations of the geochemistry, biochemistry and toxicology of this element. AbstractRelatively little information is available in the literature regarding the speciation and solubility of tellurium in aqueous solutions. The available thermodynamic data have been critically evaluated and entered into a thermodynamic database. The Joint Expert Speciation System suite of computer programs has been used to achieve thermodynamic consistency and provide a critically-selected set of equilibrium constants that can later be used for modelling purposes.

Adsorption of cadmium by an aquent New Zealand soil and Its components

Soil Research ◽  
1992 ◽  
Vol 30 (2) ◽  
pp. 159 ◽  
Author(s):  
ND Kim ◽  
JE Fergusson
Keyword(s):  
Particle Size ◽  
New Zealand ◽  
Manganese Oxides ◽  
Equilibrium Constants ◽  
Size Fraction ◽  
Silica Sand ◽  
Particle Size Fraction ◽  
Adsorption Sites ◽  
Cadmium Adsorption ◽  
Iron And Manganese

Cadmium adsorption by a New Zealand soil, three of its particle size fractions, the soil with organic matter removed, and the soil with iron and manganese oxides removed, was studied at the soil's natural pH (5.70) and at cadmium concentrations (0.01 to 0.23 �g mL-1) typical of those found in the environment. Under these conditions, the whole soil had a strong affinity for trace amounts of cadmium, adsorbing about nine-tenths of that added. Relative conditional equilibrium constants for cadmium adsorption by the soil's components decrease in the following order: clay (1.59) > [whole soil (1.00)] > soil without iron and manganese oxides (0.55) > silt (0.54) > sand (0.52) > soil without organic material (0.08) > silica sand (0.001). It is estimated that the <3.9 �m particle size fraction (22% of the soil) and the 3-9-563 pm particle size fraction (78% of the soil), contributed about 45% and 55%, respectively, to the overall capacity of the soil to adsorb cadmium. Most data obtained gives good fits to both linear and Freundlich adsorption isotherms, but is not consistent with the Langmuir adsorption model. Thus it is likely that, under the conditions studied, the soil and its components supply a range of cadmium adsorption sites with varying adsorption energies.

scholarly journals Reduction of iron and manganese concentration in dug well water by using Moramo beach sand as filter media

2019 ◽  
Vol 1153 ◽  
pp. 012078
Author(s):  
La Aba ◽  
Agung Prasetyo ◽  
Wa Ode Sitti Ilmawati ◽  
La Ode Ahmad ◽  
La Ode Sahidin
Keyword(s):  
Beach Sand ◽  
Manganese Concentration ◽  
Well Water ◽  
Filter Media ◽  
Reduction Of Iron ◽  
Dug Well ◽  
Iron And Manganese

The sticking problem during direct reduction of fine iron ore in the fluidized bed

10.30544/378 ◽  
2004 ◽  
Vol 10 (4) ◽  
pp. 309-328 ◽  
Author(s):  
Mirko Komatina ◽  
HEINRICH W. GUDENAU
Keyword(s):  
Fluidized Bed ◽  
Iron Ore ◽  
Review Paper ◽  
Direct Reduction ◽  
Reduction Process ◽  
Experimental Investigations ◽  
Inert Material ◽  
Reduction Of Iron ◽  
Fine Iron ◽  
Direct Reduction Of Iron

In this review paper described are possible chemical reactions and their thermodynamic analysis during direct reduction. The sticking mechanism during direct reduction in the fluidized bed was analysed, and the reasons for the sticking appearance explained. The most important parameters on the sticking were analysed. The ways for prevention and observation were considered. The plan for experimental investigations was proposed. The investigations could be performed in fluidized bed reactor. Coal will be used as inert material. Separately, the influence volatile content in the coal on the reduction process and sticking appearance, will be analysed. As results of these investigations would be some improvements of the method direct reduction of iron ore in the fluidized bed.

scholarly journals Impact of an historic underground gas well blowout on the current methane chemistry in a shallow groundwater system

2017 ◽  
Vol 115 (2) ◽  
pp. 296-301 ◽  
Author(s):  
Gilian Schout ◽  
Niels Hartog ◽  
S. Majid Hassanizadeh ◽  
Jasper Griffioen
Keyword(s):  
Manganese Oxides ◽  
Isotopic Fractionation ◽  
Shallow Groundwater ◽  
Gas Well ◽  
Reduction Of Iron ◽  
Shallow Groundwater System ◽  
Long Term Impact ◽  
Methane Concentrations ◽  
Iron And Manganese

Blowouts present a small but genuine risk when drilling into the deep subsurface and can have an immediate and significant impact on the surrounding environment. Nevertheless, studies that document their long-term impact are scarce. In 1965, a catastrophic underground blowout occurred during the drilling of a gas well in The Netherlands, which led to the uncontrolled release of large amounts of natural gas from the reservoir to the surface. In this study, the remaining impact on methane chemistry in the overlying aquifers was investigated. Methane concentrations higher than 10 mg/L (n = 12) were all found to have δ13C-CH4 values larger than −30‰, typical of a thermogenic origin. Both δ13C-CH4 and δD-CH4 correspond to the isotopic composition of the gas reservoir. Based on analysis of local groundwater flow conditions, this methane is not a remnant but most likely the result of ongoing leakage from the reservoir as a result of the blowout. Progressive enrichment of both δ13C-CH4 and δD-CH4 is observed with increasing distance and decreasing methane concentrations. The calculated isotopic fractionation factors of εC = 3 and εD = 54 suggest anaerobic methane oxidation is partly responsible for the observed decrease in concentrations. Elevated dissolved iron and manganese concentrations at the fringe of the methane plume show that oxidation is primarily mediated by the reduction of iron and manganese oxides. Combined, the data reveal the long-term impact that underground gas well blowouts may have on groundwater chemistry, as well as the important role of anaerobic oxidation in controlling the fate of dissolved methane.

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

2014 ◽  
Vol 20 (3) ◽  
pp. 397-405 ◽  
Author(s):  
Miroslav Sokic ◽  
Vladislav Matkovic ◽  
Branislav Markovic ◽  
Zvonko Gulisija ◽  
Aleksandra Pataric ◽  
...  
Keyword(s):  
Calcium Oxide ◽  
Raw Materials ◽  
Reduction Process ◽  
Dissociation Rate ◽  
Experimental Investigations ◽  
X Ray ◽  
Basic Operating ◽  
Alkaline Oxides ◽  
Temperature Time ◽  
Metallic Calcium

The experimental investigations defined both the technological scheme of the 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 paper. X-ray analysis reveals that the samples contain mainly calcite with small amount of dolomite. At first, the influence of temperature, time and granulometry on the calcium carbonate calcination was examined. The dissociation process was completed in 10-15 min at 1200?C, and dissociation rate increases with decreasing of particle size up to 5 mm. Afterwards, the aluminothermic reduction process of calcium oxide was investigated. At the temperature 1200?C, and vacuum of at least 3 kPa, the reduction process completed within 2 hours. The chemical composition of calcium oxide and calcium showed increased content of magnesium oxide and alkaline oxides (especially sodium).

scholarly journals Synthesis and crystal structure of a new alluaudite-like iron phosphate Na2CaMnFe(PO4)3

2016 ◽  
Vol 72 (12) ◽  
pp. 1806-1808 ◽  
Author(s):  
Semeh Jebli ◽  
Abdessalem Badri ◽  
Mongi Ben Amara
Keyword(s):  
Crystal Structure ◽  
Single Crystals ◽  
General Formula ◽  
Iron Phosphate ◽  
Structural Type ◽  
Statistical Distribution ◽  
Monoclinic Space Group ◽  
Synthesis And Crystal Structure ◽  
Space Group ◽  
Iron And Manganese

A new iron phosphate, disodium calcium manganese(II) iron(III) tris(phosphate), Na2CaMnFe(PO4)3, has been synthesized as single crystals by the flux technique. This compound crystallizes in the monoclinic space groupC2/c. The structure belongs to the alluaudite structural type and thus, it obeys theX(2)X(1)M(1)M(2)2(PO4)3general formula. Both theX(2) andX(1) sites are fully occupied by sodium, whileM(1) is occupied by calcium andM(2) exhibits a statistical distribution of iron and manganese.

Oxygen-converter reduction of iron and manganese from their oxides by components dissolved in liquid iron

2009 ◽  
Vol 39 (6) ◽  
pp. 445-449 ◽  
Author(s):  
M. K. Shakirov ◽  
I. A. Zhibinova ◽  
K. M. Shakirov ◽  
E. V. Protopopov
Keyword(s):  
Liquid Iron ◽  
Oxygen Converter ◽  
Reduction Of Iron ◽  
Iron And Manganese

Colloidal systems in soils

1994 ◽  
Vol 52 ◽  
pp. 64-65
Author(s):  
J. Thieme ◽  
J. Niemeyer ◽  
P. Guttman
Keyword(s):  
Clay Minerals ◽  
Polymeric Materials ◽  
Spatial Arrangement ◽  
High Specific Surface Area ◽  
Turnover Rates ◽  
Colloidal Systems ◽  
Chemical Conditions ◽  
Aggregation Phenomena ◽  
Iron And Manganese ◽  
Soil Colloids

In soil science the fraction of colloids in soils is understood as particles with diameters smaller than 2μm. Clay minerals, aquoxides of iron and manganese, humic substances, and other polymeric materials are found in this fraction. The spatial arrangement (microstructure) is controlled by the substantial structure of the colloids, by the chemical composition of the soil solution, and by thesoil biota. This microstructure determines among other things the diffusive mass flow within the soils and as a result the availability of substances for chemical and microbiological reactions. The turnover of nutrients, the adsorption of toxicants and the weathering of soil clay minerals are examples of these surface mediated reactions. Due to their high specific surface area, the soil colloids are the most reactive species in this respect. Under the chemical conditions in soils, these minerals are associated in larger aggregates. The accessibility of reactive sites for these reactions on the surface of the colloids is reduced by this aggregation. To determine the turnover rates of chemicals within these aggregates it is highly desirable to visualize directly these aggregation phenomena.

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