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Showing papers on "Calcium oxide published in 2017"


Journal ArticleDOI
TL;DR: In this paper, the effects of temperature, solid to liquid ratio and gas flow rate on the carbonation efficiency of fly ash were systematically investigated in a direct mineralisation process, and the results indicated that calcium in lime and portlandite had a higher reactivity towards CO 2 than that in other calcium bearing phases either crystalline or amorphous.

59 citations


Journal ArticleDOI
TL;DR: One-part geopolymer precursors are synthesized and preliminarily optimized by calcining bentonite with NaOH or Na 2 CO 3 to compare with the two-part ones as mentioned in this paper.

56 citations


Journal ArticleDOI
TL;DR: In this article, quick lime or calcium oxide (CaO) treated coconut fibers were introduced to soil cement mixture to enhance the flexural strength of tropical marine soil and three point bending tests were carried out on treated samples after 7, 14 and 28 days respectively.

54 citations


Journal ArticleDOI
TL;DR: In this article, the influence of the CaO content and decomposition of calcium-containing minerals on the bulk density, pore structure, compressive strength, and crystalline structure of ceramic foams was systematically studied by adding calcium oxide, calcium carbonate, and gypsum.

51 citations


Journal ArticleDOI
TL;DR: In this article, the authors used lime mud, the industrial waste from pulp and paper mills, as a raw material for preparing calcium oxide (CaO)-based catalysts for fast pyrolysis of Jatropha residues to bio-oil.

43 citations


Journal ArticleDOI
TL;DR: In this paper, the aggregate size effect on changes in mineralogical composition and microstructure of lime-treated compacted soils was investigated, where three soil powders with different maximum aggregate sizes were prepared prior to the treatment with 2% of lime.

39 citations


Journal ArticleDOI
TL;DR: In this article, three kinds of novel diatomite/ground calcium carbonate composite humidity control materials were prepared with different calcination temperatures using diatomites and ground calcium carbonates (GCC) as raw materials.

37 citations


Journal ArticleDOI
TL;DR: The addition of lime has a pronounced effect on soft soils as mentioned in this paper, which is problematic because of their low strength, low bearing capacity, low permeability, and high compressibility.
Abstract: Soft soils are problematic because of their low strength, low bearing capacity, low permeability, and high compressibility. The addition of lime has a pronounced effect on such soils. In th...

35 citations


Journal ArticleDOI
TL;DR: In this article, the effects of adding zirconia-based ceramic dopants and coating sorbents with highly crystalline Zirconium dioxide (ZrO2) layers derived from the hydrolysis of ZrO 2 crystals were investigated.
Abstract: Calcium oxide (CaO) has been investigated as a high-temperature performance sorption material for carbon capture due to its high carbon dioxide (CO2) capacity, low cost, and environmental benignity. Unfortunately, commercialized application of CaO materials has been hindered by severe capacity loss during cycling operations. In an attempt to overcome these problems, this study investigated the effects of adding zirconia-based ceramic dopants and coating sorbents with highly crystalline zirconium dioxide (ZrO2) layers derived from the hydrolysis of zirconium butoxide to control the growth of ZrO2 crystals. Uncoated natural Cadomin delivered a high CO2 capture capacity of more than 13 mol CO2/kg, while the zirconia-coated sorbents showed excellent cycling stability corresponding to a maximum capacity of retention of 79% after 21 cycles at high temperatures. More importantly, the highly crystalline ZrO2-coated sorbents doped by zirconia-based sorbents exhibited a significantly lower decay capacity compared t...

34 citations


Journal ArticleDOI
TL;DR: In this article, the authors used CO2 in combination with methanol for dimethyl carbonate (DMC) synthesis in presence of cerium-calcium mixed oxide catalysts.

34 citations


Journal ArticleDOI
19 May 2017
TL;DR: In this paper, the effect of calcium oxide on the crushing strength, reduction, and smelting performance of high-chromium vanadium-titanium magnetite pellets (HCVTMP) was studied.
Abstract: The effect of calcium oxide on the crushing strength, reduction, and smelting performance of high-chromium vanadium–titanium magnetite pellets (HCVTMP) was studied in this work. The main characterization methods of an electronic universal testing machine (EUTM), X-ray fluorescent (XRF), inductively-coupled plasma-atomic emission spectroscopy (ICP-AES), X-ray diffraction (XRD), and scanning electron microscope-energy disperse spectroscopy (SEM-EDS) were employed. The crushing strength was affected by the mineral phases generated during oxidative baking and the subsequently-formed pellet microstructures owing to CaO addition. The reduction and smelting properties of HCVTMP with different CaO additives were measured and characterized with different softening-melting-dripping indices. Although HCVTMP showed the highest crushing strength with CaO addition of ca. 2 wt %, more CaO addition may be needed to achieve high permeability of the furnace burdens and a good separation condition of the slag and melted iron. In the formation process of the slag and melted iron, it can be determined that CaO could have a relationship with the transformation behavior of Cr, V, and Ti to some extent, with respect to the predominant chemical composition analysis of ICP-AES and XRF. With the microscopic examination, the restraining formation of Ti(C,N) and the promoting formation of CaTiO3 are in accordance with the improved melting-dripping indices, including the decrease of the maximum external static load and gas permeability, and the increase of the melting-dripping zone and dripping difficulty.

Journal ArticleDOI
TL;DR: In this article, the agglomeration behavior of the calcium hydroxide/calcium oxide particles as a thermochemical energy storage material at the molecular level was investigated with the reactive force field.
Abstract: Thermochemical energy storage is a promising alternation in heat recovery application compared to phase change energy storage. However, cycling instability caused by agglomeration of the reactant particles is the main problem that hinders the application of this system. The present paper focuses on the agglomeration behavior of the calcium hydroxide/calcium oxide particles as a thermochemical energy storage material at the molecular level. Molecular dynamics simulations with the reactive force field were carried out to investigate the agglomeration of two nano-CaO/Ca(OH)2 particles. The results indicated that the agglomeration rate of two Ca(OH)2 particles was faster than that of two CaO particles in the presence of H2O, which was attributed to the greater spatial displacements of atoms in the reactant particles when thermochemical reaction occurred. The present of H2O could accelerate the agglomeration of the CaO particles. Moreover, the hydration of the CaO agglomeration lump was more difficult than tha...

Patent
04 May 2017
TL;DR: In this article, a high strength glass fiber is prepared by following steps: weighing raw materials according to a mass percentage of 50-60% silica sol, 24-31% aluminum sol, 8-11% magnesia, 4-5% calcium oxide, 0.1-2% titanium dioxide, 0-0.5% ferric oxide, Niobium pentoxide, 05-1.5%, antimony trioxide and bismuth nitrate.
Abstract: A high strength glass fiber is prepared by following steps: weighing raw materials according to a mass percentage of 50-60% silica sol, 24-31% aluminum sol, 8-11% magnesia, 4-5% calcium oxide, 0.1-2% titanium dioxide, 0-0.5% ferric oxide, 0.5-2% niobium pentoxide, 0.5-1.5% antimony trioxide, 0.3-1.5% bismuth nitrate, and 0.1-0.5% boric acid. Deionized water is added. The raw material undergoes mixing by ball milling, spray-drying, calcining, isostatic pressing, melting, and wire-drawing. The invention adopts silicon sol, aluminum sol and bismuth nitrate. Through ball milling and spray-drying, silicon aluminum barium plasmas is evenly coated on surface of other oxide powders. Then nano particles, of silica, alumina and bismuth oxide are obtained by calcining. Under the effect of the high specific surface energy of nano particles, and the close contact of each component, high strength glass fiber is obtained in relatively low fiber drawing temperature while the glass melting temperature and time are significantly reduced.

Journal ArticleDOI
01 Sep 2017-Fuel
TL;DR: In this article, the catalytic effect of calcium on the steam gasification of Shengli chars was studied in detail by SEM-EDX, XRD, Raman, FTIR and XPS.


Journal ArticleDOI
TL;DR: In this article, the effect of ball milling and heat treatment on slag particle size on the efficiency and morphological properties of precipitated calcium carbonate (PCC) produced from calcium oxide were investigated for different extraction solvent, temperatures, CO2 injection rate and solvent concentration.

Journal ArticleDOI
TL;DR: In this paper, the authors compare the performance of paving when stabilized with either cement or lime and found that the latter is superior to the latter in terms of quality. But, the results were limited.
Abstract: Phosphogypsum (PG) is a by-product of the phosphoric acid fertilizer industries that has possible applications in paving when stabilized with cement or lime. This study’s aim is to compare ...

Journal ArticleDOI
27 Feb 2017-Minerals
TL;DR: In this article, the vanadium extraction from coal by roasting with MgO and leaching with sulfuric acid has been investigated, and the mechanism analysis of stone coal roasting using mgO was studied.
Abstract: In this paper, the extraction of vanadium from stone coal by roasting with MgO and leaching with sulfuric acid has been investigated, and the mechanism analysis of stone coal roasting with MgO was studied. The results indicated that under the conditions that the mass fraction of the particles with grain size of 0–0.074 mm in raw ore was 75%, the roasting temperature was 500 °C, the roasting time was 1 h, MgO addition was 3 wt %, the sulfuric acid concentration was 20 vol %, the liquid-to-solid ratio was 1.5 mL/g, the leaching temperature was 95 °C, and leaching time was 2 h, resulting in a vanadium leaching efficiency of 86.63%, which increased by 7.73% compared with that of blank roasting. The mechanism analysis showed that the degree of calcite decomposition was low and, thus, magnesium vanadate was more easily formed than calcium vanadate below 500 °C. Moreover, magnesium vanadate was easier to dissolve than calcium vanadate during the sulfuric acid leaching process. Thus, the vanadium leaching efficiency was enhanced by using MgO as a roasting additive below 500 °C. Additionally, at high temperature the formation of tremolite would consume calcium oxide produced from the decomposition of calcite, thus, the formation of calcium vanadate was hindered, and V2O5 would react with MgO to form magnesium vanadate. Therefore, the vanadium leaching efficiency of roasting with MgO was higher than that of blank roasting at high temperature.

Journal ArticleDOI
01 Jun 2017-Fuel
TL;DR: In this article, density functional theory (DFT) calculations were performed to investigate SO x binding to CaO surfaces functionalized by other flue gas components, and the results showed that the most stable conformation on the surface is in the form of either a sulfite- or sulfate-like structure.

Journal ArticleDOI
TL;DR: In this paper, the impact of reactivation strategies on carbonate formation through detailed study using in-situ infrared spectroscopy surface and bulk carbonate forming regimes were readily distinguished allowing the influence of temporal, hydration and thermodynamic conditions within each regime to be studied Surface chemistry of CaO during two initial cycles was shown to change Significantly, it was shown that the CaO surface produced from the calcination of Ca(OH)2 possessed more highly reactive sites compared to the surface produced by CaCO3.

Journal ArticleDOI
TL;DR: In this paper, the effects of CaO and modified CaO on copper-based catalysts for methanol synthesis have been investigated, where oyster shell-derived calcium oxide promoters were employed as an additive in a zirconia-supported copper catalyst.
Abstract: This research aims to investigate the effects of CaO and modified CaO on copper-based catalysts for methanol synthesis. The CaO and modified CaO were derived from oyster shell and employed as an additive in a zirconia-supported copper catalyst (Cu/ZrO 2 ). The physical and chemical properties of the catalysts were characterized by XRD, BET, CO 2 -TPD, H 2 -TPD and XANES. The addition of oyster shell-derived calcium oxide promoters to the catalysts significantly improved their chemical properties and methanol synthesis possibly owing to impurities and defects in the crystal structure of natural calcium oxide.

Journal ArticleDOI
TL;DR: In this article, a thermal chemical energy storage (TCES) material was developed that utilizes surplus heat from nuclear power plants during low demand of electricity, the target temperature of reusing heat is over 450 °C which is utilized for next generation nuclear reactors.

Journal ArticleDOI
TL;DR: In this paper, the authors examined a number of mixed metal oxides supports, such as alumina, silica, titania, magnesia and molybdena, with zirconia (ZrO 2 ) for stabilization of calcium (Ca) based sorbents directly produced from a co-precipitation method.
Abstract: Zirconia-stabilized Ca-based sorbent has been previously investigated for cyclic CO 2 capture processes; however, the cost of pure zirconia may be a matter of concern. The cost of sorbent can be decreased by addition of a low cost second metal oxide with zirconia-stabilized Ca-based sorbent. This study examined a number of mixed metal oxides supports, such as alumina, silica, titania, magnesia and molybdena, with zirconia (ZrO 2 ) for stabilization of calcium (Ca) based sorbents directly produced from a co-precipitation method. Selected metal oxide supports (i.e. alumina and silica) are commonly used in catalytic steam gasification. The proposed novel strategy aimed at enhancing sorbent stability, increasing surface area, decreasing cost of zirconia-stabilized sorbents and investigating the effects of the common used supports in catalytic steam gasification on the performance of Ca-based sorbents. The optimal composition for the activity of ceramic-stabilized calcium oxide (CaO) samples under mild operating conditions was determined to be 10 wt.% ceramic incorporated in the sorbent. The results indicated considerable sorbent stability and capacity improvement for mixed metal oxide zirconia-stabilized CaO over those of pure CaO, which showed significant cyclic capacity decay under similar conditions. Among the studied materials, aluminum zirconate, calcium zirconate, and zirconium molybdate stabilized sorbents showed the best initial uptake and performances in severe operating conditions over 60 cycles. However, titania, silica and magnesia supports showed negative effect on the sorbent performance.

Journal ArticleDOI
TL;DR: In this paper, the authors showed that the in-situ calcium carbonate formation process improved the optical quality of the recycled old newspaper by covering colored impurities with newly formed calcium carbonates, and improved the carbonate retention in papermaking process by attaching them to fibers.

Journal ArticleDOI
TL;DR: In this article, the potential of waste seashell from cockle for producing low cost porous calcium oxide for CO 2 capture was investigated, and the adsorption equilibrium of CO 2 on porous calcined calcium oxide with presence of water was measured using a static volumetric technique at 2°C for pressures up to 36 bar.

Journal ArticleDOI
15 Jun 2017-Fuel
TL;DR: In this paper, four calcium-containing materials (calcium hydroxide, commercial hydrated lime, calcium oxide and calcium carbonate) were evaluated as catalysts in the photodegradation of Rhodamine 6G (Rh6G) under UV radiation.

Journal ArticleDOI
TL;DR: In this article, different face velocity and carbon dioxide (CO2) initial concentration were studied to examine the adsorption behavior of calcium oxide (CaO) impregnated activated carbon (AC) filter and also to discuss three kinetic models.
Abstract: We studied different face velocity and carbon dioxide (CO2) initial concentration to examine the adsorption behavior of calcium oxide (CaO) impregnated activated carbon (AC) filter and also to discuss pseudo-first-order, pseudo-second-order and intra-particle diffusion three kinetic models. The experimental results show that saturation time and saturation capacity were decreased and increased with higher inlet concentration at the same face velocity, respectively. Simulation results show that pseudo-second-order correlation coefficient (r22 = 0.921) is higher than pseudo-first-order (r12 = 0.7815) and intra-particle diffusion (ri2 = 0.905). Therefore, the adsorption process of CO2 onto CaO impregnated AC filter media is appropriate for the pseudo-second-order kinetic model.

Journal ArticleDOI
TL;DR: In this paper, a two-phase reactor model was developed using a system of ordinary differential equations in MATLAB to model the carbonation reaction and therefore determine the kinetics of calcium oxide in a pressurized fluidized bed reactor as part of the calcium looping cycle.
Abstract: A two-phase reactor model has been developed using a system of ordinary differential equations in MATLAB to model the carbonation reaction and therefore determine the kinetics of calcium oxide in a pressurized fluidized bed reactor as part of the calcium looping cycle. The model assumes that the particulate and bubble phases are modeled as a CSTR and a PFR, respectively. The random pore model developed by Bhatia and Perlmutter1 is incorporated into the system of equations to predict the rate of carbonation for pressures up to 5 bara total, and CO2 partial pressures up to 150 kPa. The surface rate constant and product layer diffusivity in the random pore model expression were obtained by fitting the model to experimental data for a range of pressures, CO2 concentrations, and temperatures by minimization of the residual sum of squares. The surface rate constants were found to be between 3.05 and 12.9 × 10–10 m4 mol–1 s–1 for a temperature range of 550 to 750 °C. The product layer diffusivities were found to...

Journal ArticleDOI
TL;DR: In this paper, the effects of reaction variables such as reaction time, microwave power, methanol/oil molar ratio, and catalyst loading on the yield of biodiesel were investigated by gas chromatography-mass spectrometry (GC-MS).

Patent
29 Mar 2017
TL;DR: In this article, a system consisting of a melting bath bed calcium carbide furnace, a coal gas chilling tower and a coal powder pyrolysis tower is described, where the interior of the furnace is defined to form a reaction space and a calcide liquid melting pool from top to bottom.
Abstract: The invention discloses a system and a method for preparing calcium carbide. The system comprises a melting bath bed calcium carbide furnace, a coal gas chilling tower and a coal powder pyrolysis tower, wherein the interior of the melting bath bed calcium carbide furnace is defined to form a reaction space and a calcium carbide liquid melting pool from top to bottom, a blocky calcium carbide inlet, a natural gas nozzle, an oxygen nozzle and a furnace top gas outlet are arranged in the reaction space, the calcium carbide liquid melting pool is provided with a calcium carbide liquid outlet, and the melting bath bed calcium carbide furnace is provided with a nozzle for supplying mixed powder comprising a carbon raw material and a calcium raw material by virtue of natural gas; the coal gas chilling tower is provided with a cold coal gas inlet, a furnace top gas inlet, a limestone inlet, a mixed coal gas outlet and a calcium oxide outlet, the furnace top gas inlet is connected with the furnace top gas outlet, the calcium oxide outlet is connected with the nozzle for supplying mixed powder; and the coal powder pyrolysis tower is provided with a coal gas inlet, a coal powder inlet, a semi-coke outlet and a mixed gas outlet, the coal gas inlet is connected with the mixed coal gas outlet, and the semi-coke outlet is connected with the nozzle for supplying mixed powder. By adopting the system to prepare the calcium carbide, the production efficiency is relatively high, and the energy consumption is relatively low.