Calcium Sulfate Precipitation in the Presence of Nondominant Calcium Carbonate:  Thermodynamics and Kinetics

2001 ◽  
Vol 40 (16) ◽  
pp. 3570-3578 ◽  
Author(s):  
R. Sheikholeslami ◽  
M. Ng
Keyword(s):  
Calcium Carbonate ◽  
Calcium Sulfate ◽  
Thermodynamics And Kinetics

scholarly journals First-principles study of calcium-based sulfur fixers and their products

2021 ◽  
pp. 350-350
Author(s):  
Guoyan Chen ◽  
Jianing Chen ◽  
Anchao Zhang ◽  
Haoxin Deng ◽  
Yanyang Mei ◽  
...  
Keyword(s):  
Calcium Carbonate ◽  
Power Plant ◽  
Thermodynamic Properties ◽  
Calcium Oxide ◽  
First Principles ◽  
Calcium Sulfate ◽  
Density Functional ◽  
Stable State ◽  
Generalized Gradient ◽  
Calcium Sulphoaluminate

Calcium-based sulfur-fixing agent, as the main sulfur-fixing product, is widely used in power plant boiler systems. In order to further study the thermodynamic properties and reaction characteristics of calcium-based sulfur fixing agent and its products, the method of combining power plant experiment with theory was used. The electronic structure, thermodynamic properties and density of states of quicklime, limestone, calcium sulfate and calcium sulphoaluminate have been calculated based on the first-principles ultra-soft pseudopotential plane wave method of density functional theory. The generalized gradient approximation algorithm isused to optimize the structure of various minerals to achieve the most stable state. The results show that the enthalpy, entropy, specific heat capacity at constant pressure and Gibbs free energy of calcium sulfonate vary greatly from 25K to 1000K, while the change of calcium oxide is small, and that of calcium carbonate and calcium sulfate are between them. It shows that calcium sulphoaluminate has strong stability and more energy is needed to destroy the molecular structure of calcium sulphoaluminate. Calcium oxide is the most unstable and requires less energy to react; Calcium carbonate and calcium sulfate are in between. The variation range of calcium sulfate is greater than that of calcium carbonate, indicating that the stability of calcium sulfate is higher than that of calcium carbonate. The experimental results show that the desulfurization efficiency of generating calcium sulphoaluminate is much higher than that of only generating calcium sulfate, indicating that calcium sulphoaluminate is very stable, which is consistent with the calculated results.

scholarly journals The study of compositions based on parkent kaolin clay

2018 ◽  
pp. 29-33
Author(s):  
M. Kh. Rumi ◽  
Sh. K. Irmatova ◽  
M. A. Zufarov ◽  
Sh. A. Fayziev ◽  
E. P. Mansurova ◽  
...  
Keyword(s):  
Calcium Carbonate ◽  
Liquid Glass ◽  
Calcium Sulfate ◽  
Kaolin Clay ◽  
Acid Activation ◽  
Kaolinite Clay ◽  
Aluminum Ions ◽  
Heat Treated ◽  
Rate Of Extraction ◽  
Subsequent Acid

The results of studies of the structure and composition of compositions based on red-burning kaolinite clay and calcium carbonate, heat-treated at 500oC, in the process of acid activation are presented. It is shown that when a 12 % solution of H2SO4is applied, leaching of iron and aluminum ions and the formation of calcium sulfate occur while maintaining the structure of kaolinite. The introduction of liquid glass into the composition of the material leads to the destruction of the structure of kaolinite, which contributes to an increase in the rate of extraction of aluminum ions during the subsequent acid activation. The components of the compositions with Ca2+and Fe3+in the presence of liquid glass are passivated by active amorphous silica formed during the reaction of liquid glass with CO2air.Ill. 2. Ref. 17. Tab. 1.

Real-time detection of early-stage calcium sulfate and calcium carbonate scaling using Raman spectroscopy

2020 ◽  
Vol 596 ◽  
pp. 117603 ◽  
Author(s):  
Omkar D. Supekar ◽  
Danielle J. Park ◽  
Alan R. Greenberg ◽  
Juliet T. Gopinath ◽  
Victor M. Bright
Keyword(s):  
Raman Spectroscopy ◽  
Calcium Carbonate ◽  
Real Time ◽  
Calcium Sulfate ◽  
Early Stage ◽  
Real Time Detection

Analysis of Physical and Chemical Features of Sintering Dust and Study of Recycling Treatment

2015 ◽  
Vol 768 ◽  
pp. 350-362
Author(s):  
Bin Pei ◽  
Guang Zhan ◽  
Zhan Cheng Guo ◽  
Jin Tao Gao
Keyword(s):  
Calcium Carbonate ◽  
Potassium Chloride ◽  
Sodium Carbonate ◽  
Calcium Sulfate ◽  
Sodium Carbonate Solution ◽  
Potassium Sulfate ◽  
Water Leaching ◽  
Leaching Experiment ◽  
Leaching Solution ◽  
Physical And Chemical

Several physical and chemical detection methods were used to study the basic properties of sintering dust collected from Baogang Steel Corporation. The result shows that the major constituents of the electrostatic precipitator dust (ESP dust) were KCl, NaCl, Fe2O3 and Fe3O4. Water leaching experiment on the sintering dust had shown that the KCl in the ESP dust could be separated and recovered by water leaching and fractional crystallization. Component analysis of leaching solution showed that the massive calcium sulfate in the leaching solution should be removed first in order to obtain the pure potassium salt. In order to provide theoretical guidance to inhibit the dissolution of calcium ions from the sintering dust, the water leaching experiment of ESP dust and the dissolution behavior of CaSO4 in the potassium chloride, sodium chloride, potassium sulfate and their mixed salt solution were studied. Result showed that, a lower liquid-solid ratio should be chosen in the leaching process to inhibit the dissolution of calcium sulfate dehydrate. Using sodium carbonate solution as a precipitating agent, the influences of the concentration of sodium carbonate solution, reaction temperature, stirring speed on the preparation of the spherical calcium carbonate were studied. Spherical calcium carbonate with good dispersing performance and grain size distribution in nanometer range of less than 10μm was obtained. The production technology of potassium sulfate by double decomposition was sutdied, the results showed that over 80% and 12.76% of the recovery rate of potassium sulfate and potassium chloride ammonium compound fertilizer could be obtained. Furthermore, a potassium recovery process with joint production of spherical calcium carbonate and potassium sulfate was designed. This process is technically viable and considerable in economic benefit.

Design and Optimization of the Preparation of Calcium Carbonate from Calcium Sulfate and Ammonium Bicarbonate

2014 ◽  
Vol 12 (1) ◽  
pp. 611-621 ◽  
Author(s):  
Jingcai Zhao ◽  
Xingfu Song ◽  
Ze Sun ◽  
Yanxia Xu ◽  
Jianguo Yu
Keyword(s):  
Calcium Carbonate ◽  
Calcium Sulfate ◽  
Polynomial Equation ◽  
Ammonium Bicarbonate ◽  
Experimental Result ◽  
Process Conditions ◽  
Single Factor ◽  
Design And Optimization ◽  
Optimum Parameters ◽  
Factor Effect

Abstract Simulation on single factor effect was used for the design and optimization of the preparation of calcium carbonate from calcium sulfate (DH) and ammonium bicarbonate. This study shows that simulation on single factor effect is effective because the experimental results are close to predicted results. Furthermore, response surface method based on a central composite design was used to determine the range of parameters to achieve a highly efficient conversion of DH. The results indicate that the significant parameters that affected the conversion of DH were ratio of carbon to sulfur, temperature, concentration of ammonium bicarbonate, and stirring speed. The strength order of factors is as follows: ratio of carbon to sulfur > concentration of ammonium bicarbonate > stirring speed > temperature. A quadratic polynomial equation was established using multiple regression analysis. The optimum parameters were determined as follows: 2.10 for ratio of carbon to sulfur, 320.35 K for temperature, 337.31 rpm for the stirring speed, and 1.75 mol · L−1 for bicarbonate concentration. The corresponding conversion rate of the experimental result was 99.7%, which was highly consistent with the predicted value of 99.9%. Based on model and the optimum parameters, products of vaterite, with ammonium sulfate crystal of grade A, can be obtained. Equipotential lines of conversional rate and desired process conditions were provided as well.

Performance of a non-phosphorus antiscalant on inhibition of calcium-sulfate precipitation

2012 ◽  
Vol 66 (1) ◽  
pp. 193-200 ◽  
Author(s):  
Xiaoxu Xue ◽  
Change Fu ◽  
Na Li ◽  
Fangfang Zheng ◽  
Weiben Yang ◽  
...  
Keyword(s):  
Calcium Sulfate ◽  
Water Systems ◽  
Sem Analysis ◽  
Solution Ph ◽  
X Ray ◽  
Thermodynamics And Kinetics ◽  
Scale Inhibition ◽  
Calcium Sulfate Scale ◽  
Different Temperatures ◽  
Strong Ability

The aim of this study is to report on the performance of a novel non-phosphorus antiscalant, acrylic acid (AA)-allylpolyethoxy carboxylate (APEC), being developed for calcium-sulfate scale inhibition in industrial water systems. The performance of AA-APEC on calcium-sulfate scale inhibition was compared with that of the two commercial inhibitors, polyamino polyether methylene phosphonates (PAPEMP) and polyacrylic acid (PAA), containing the same polyethylene glycol segments or carboxyl functional groups as AA-APEC. The study indicated that AA-APEC could act as a highly effective calcium sulfate inhibitor, having strong ability to inhibit the precipitation of calcium sulfate at a dosage of 2 mg L−1, showing approximately 83.6% inhibition. The results also showed that AA-APEC dosage, the solution pH, inhibiting temperature, concentration of Ca2+, and SO42− all play important roles in inhibiting calcium-sulfate precipitation. The precipitation thermodynamics and kinetics at different temperatures were also discussed. X-ray diffractometer (XRD) and scanning electron microscope (SEM) analysis showed that AA-APEC strongly affected the texture and the morphology of the deposited calcium sulfate. Calcium sulfate has been inhibited through stabilization by adsorption onto crystal growth sites of nascent crystals altering their morphology.

Solidification of Greenhouse Gas Carbon Dioxide

2014 ◽  
Vol 472 ◽  
pp. 879-883
Author(s):  
Wei Yin
Keyword(s):  
Carbon Dioxide ◽  
Calcium Carbonate ◽  
Ambient Temperature ◽  
Calcium Sulfate ◽  
Exothermic Reaction ◽  
Ammonium Bicarbonate ◽  
Second Order Reaction ◽  
Carbon Dioxide Gas ◽  
Water Media ◽  
Closed Reactor

The feasible routine of carbon dioxide solidification is developed, which employs carbon dioxide with calcium sulfate and ammonia to obtain calcium carbonate and ammonium sulfate at ambient temperature. The process of carbon dioxide solidification is a spontaneous and exothermic reaction, whose possesses the rate constants of the second order reaction, which can be attributed to carbon dioxide gas dissolving the water media and carbon dioxide reacted with ammonia to produce ammonium bicarbonate. Calcium sulfate changing rapidly into calcium carbonate accelerates the process of reaction of carbon dioxide reacted with ammonia. The optimization process parameters of carbon dioxide solidification are a 0.075-MPa of CO2, a 0.5-mol of CaSO4·2H2O, a 0.5-mol of NH3·H2O and a 100-ml of H2O in a closed reactor, which is able to obtain 100% CO2 gas solidification efficiency within 4 minutes at ambient temperature.

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