SEM images of gypsum crystals synthesized at 90 °C from sulphuric acid
Download scientific diagram | SEM images of gypsum crystals synthesized at 90 °C from sulphuric acid 15 wt% and a 20 wt% suspension of calcite B injected with an inlet flow of : (a) 20 ml/min, (b ...
Co-preparation of calcium sulfoaluminate cement and …
The CaSO4 and CaO derived from the partial decomposition of industrial by-product gypsum are used to form calcium sulfoaluminate clinker minerals, and the SO2 …
Calcium sulfate, anhydrous, 99%, Thermo Scientific Chemicals
Used as Portland-cement retarder; tile and plaster; It is the source of sulfur and sulfuric acid; Also used in polishing powder and paints, dyeing and calico . It is likewise employed in zinc metallurgy. It is employed in drying industrial gases, solids and many organic liquids. In granulated form it is used as soil conditioner.
Effects of the Impurities on the Habit of Gypsum in Wet …
There is a poor understanding of the effect of impurities in phosphate rock on the crystal habit of gypsum during wet-process phosphoric acid production. The present work studies the effects of Al3+, SiF62-, and F- on the habit of gypsum in an MSMPR crystallizer. It is found that the gypsum crystal shape changes little in the presence of …
Kinetics of gypsum formation and growth during the
One of the most important boron minerals, colemanite, is dissolved in aqueous sulfuric acid to produce boric acid whereby gypsum is formed as byproduct. Filtration of gypsum has an important role in boric acid production because gypsum affects the efficiency, purity and crystallization of boric acid. The formation and growth kinetics of gypsum during …
Formation of calcium sulfate whiskers from CaCO 3
The influence of Na2HPO4·12H2O on the hydrothermal formation of hemihydrate calcium sulfate (CaSO4·0.5H2O) whiskers from dihydrate calcium sulfate (CaSO4·2H2O) at 135 °C was investigated.
Semi-batch crystallization of gypsum from calcite and sulfuric acid
These scrubbers convert sulfur oxides into solid sulfate and sulfite sludge, which must then be disposed of This sludge is a result of reacting limestone with sulfur dioxide to precipitate calcium ...
Production and resource utilization of flue gas desulfurized …
The preparation of α-hemihydrate gypsum (α-HH) is an effective way to realize the high-value utilization of FGD gypsum. The formation mechanism and crystal …
Gypsum in construction: origin and properties
In the calcium sulfate strata, formed as a result of sea water evaporation, gypsum and anhydrite appear side by side (horizontally or vertically), and occasionally as a mixture. …
Effect of gypsum addition on acid resistance of Ye'elimite rich calcium …
Figure 15 Acid consumption (5% sulfuric acid) of binders based on powder test [Note: acid consumption from the pH of DP to pH of 2] As discussed in [36], the titrator stabilizing point (SP) was ...
Gypsum Crystallization and Hydrochloric Acid Regeneration …
To this end a reactive crystallization process involving stage-wise reaction of concentrated calcium chloride solution (up to 5 mol/L) with concentrated sulfuric acid (up to 18 mol/L) at ...
PRODUCTION OF CALCIUM SULPHATE ALPHA …
Alpha-hemihydrate of calcium sulphate can be obtained by suspending gypsum in boiling or almost boiling aqueous solution of an inorganic acid salts or sulphuric acid at atmospheric pressure. The task was to try to obtain it from citrogypsum in unheated solution of this acid. The experiment proved it possible if 10, 15, 20, 30, or 40 wt% solution was …
Autoclave‐Free Formation of α‐Hemihydrate Gypsum
The solubility of calcium sulfate dihydrate (DH) and α-calcium sulfate hemihydrate in formamide aqueous solutions with 0–13 m formamide at temperatures from 303.15 to 363.15 K was measured by ...
Preparation of α-calcium sulfate hemihydrate from industrial …
The preparation of α-calcium sulfate hemihydrate (α-HH) from industrial by-product gypsum is an important way to solve the massive accumulation. α-HH possessing larger, dense and well-grown crystals with fewer cracks and pores has high added value and a wide range of application.
Production of calcium sulphate alpha-hemihydrate from …
The calcium sulphate alpha-hemihydrate was formed when 10, 15, 20, 30, or 40 wt.% acid solution was used at the lowest gypsum/acid solution mixing ratio (experiments 13, 19, 25, 31, 37) and 20 wt.% H 2SO 4 at the mixing ratio values of 0.125 and Ceramics − Silikáty 44 (3) 104-108 (2000) Production of calcium sulphate alpha-hemihydrate from ...
Preparation of calcium sulfate from recycled red …
Keywords Red gypsum · Acidic wastewater · Cycle times · Activity index · Desulfurization Introduction Red gypsum (RG) is obtained from the production of tita-nium dioxide, by the sulfuric acid method, which is mainly composed of calcium sulfate and amorphous ferric hydrox-ide [1, 2]. It is estimated that the annual production of RG
Phosphate Industry: Gypsum Crystallization under the …
curves of gypsum under industrial conditions of phosphoric acid production. The present study investigated the effect of the phosphoric acid concentration, as well as the effects of the Mg 2+, Al 3+ and Cd 2+ ions, as impurities, on the solubility and the metastable zone width of calcium sulfate dihydrate
Purification of calcium fluoride (CaF2) sludge by selective carbonation
DOI: 10.1016/J.JECE.2020.104510 Corpus ID: 224989357; Purification of calcium fluoride (CaF2) sludge by selective carbonation of gypsum @article{Takaya2020PurificationOC, title={Purification of calcium fluoride (CaF2) sludge by selective carbonation of gypsum}, author={Yutaro Takaya and Shota Inoue and …
Preparation of calcium carbonate by indirect carbonation
The accelerated mineral carbonation of RG was first performed using different concentrations of sulfuric acid (H2SO4) from 0.5 M to 2 M to extract the calcium ions from the RG.
Effect of gypsum addition on acid resistance of Ye'elimite rich calcium …
DOI: 10.1016/j.cemconcomp.2023.105335 Corpus ID: 264136444; Effect of gypsum addition on acid resistance of Ye'elimite rich calcium sulfoaluminate cement @article{Damion2023EffectOG, title={Effect of gypsum addition on acid resistance of Ye'elimite rich calcium sulfoaluminate cement}, author={Tom Damion and Piyush …
Recycling, reusing and environmental safety of industrial by …
Titanium gypsum (TG), also known as red gypsum, represented a reddish-yellow industrial solid waste produced during sulfuric acid method of titanium dioxide …
Structural characteristic and formation mechanism of …
DOI: 10.1016/J.PARTIC.2021.04.010 Corpus ID: 236602669; Structural characteristic and formation mechanism of hemihydrate calcium sulfate whiskers prepared using FGD gypsum @article{Zhang2021StructuralCA, title={Structural characteristic and formation mechanism of hemihydrate calcium sulfate whiskers prepared using FGD gypsum}, …
Crystal structure formation of hemihydrate calcium sulfate …
DOI: 10.1016/j.poly.2019.114140 Corpus ID: 203134726; Crystal structure formation of hemihydrate calcium sulfate whiskers (HH-CSWs) prepared using FGD gypsum @article{Zhang2019CrystalSF, title={Crystal structure formation of hemihydrate calcium sulfate whiskers (HH-CSWs) prepared using FGD gypsum}, author={Xiaoting Zhang …
Co-preparation of calcium sulfoaluminate cement and sulfuric acid
The CaSO 4 and CaO derived from the partial decomposition of industrial by-product gypsum are used to form calcium sulfoaluminate clinker minerals, and the SO 2 released during the production of calcium sulfoaluminate clinker is collected and transformed into sulfuric acid. The experimental results show that calcium …
(PDF) Production of calcium sulphate alpha-hemihydrate
Alpha-hemihydrate of calcium sulphate can be obtained by suspending gypsum in boiling or almost boiling aqueous solution of an inorganic acid salts or sulphuric acid at atmospheric pressure.
Production of sulfur from gypsum as an industrial …
Gypsum (CaSO4.2H20) is produced by increasingly more industrial processes, for instance, when calcium carbonate or lime is used to neutralize effluents contain- ing …
Effect of Ionic Impurities on the Crystallization of Gypsum in …
The dihydrate phosphoric acid production process was simulated in a bench-scale glass reactor. The influences of selected ionic contaminants (Na+, K+, Mg2+, Al3+, F-, and Fe3+) on the crystallization of the gypsum byproduct were investigated. Except for fluorine, the presence of the impurities aided gypsum precipitation, with iron …
Progress in the Preparation of Calcium Carbonate by Indirect …
Reacting CO 2 from flue gas with calcium from the industrial by-product gypsum (CaSO 4) produces calcium carbonate more economically than the traditional …
Autoclave‐Free Formation of α‐Hemihydrate Gypsum
Flue gas gypsum may be converted to α-hemihydrate by suspending the starting material in inorganic salt solutions of high concentration or in diluted sulfuric acid and maintaining the suspension at boiling, or near boiling temperature for a period of time. The crystal morphology of the produced α-hemihydrate gypsum and, thus, its quality depend …
IOM3 | Synthetic gypsum derived from industrial waste
The joint research team began with the premise they could obtain synthetic gypsum from calcium carbonate and sulphuric acid – with the required crystal …