Gypsum Dihydrate Deposition Environment
Gypsum: Properties, production and applications
Gypsum is a very soft mineral composed of calcium sulfate dihydrate and often occurs in nature as flattened and often twinned crystals and transparent cleavable masses called selenite.
Ionic Liquid-Functionalized ZnO Nanomaterial
Other researchers have improved the adsorption and deposition of magnetic nanoparticles on metal surfaces by applying an external magnetic field to control their alignment, which helps create protective films with superior friction-reducing and anti-wear properties[13], [14], [15]. ... the addition of various additives to meet the diversity of ...
Environmental Impact of Silica and Gypsum …
Alarming Impacts of gypsum mining on Ecosystems and Water Resources. Gypsum mining, predominantly carried out for its use in the construction industry, has its own set of environmental challenges. Gypsum …
Dehydration Pathways of Gypsum and the …
A review with 9 refs. Calcium sulfate, commonly known as natural gypsum, is found in nature in different forms, mainly as the dihydrate (CaSO4.2H2O) and anhydrite (CaSO4). They are products of …
Contribution of atmospheric deposition to the formation …
Calcium sulphate dihydrate (gypsum) is the major component at 76.5%, with calcium carbonate at 1.8% and total carbon (Cc) and noncarbonate carbon (Cnc) at 27.6 and 25.5 mg/g, respectively. ... Gypsum is due to the wet and dry deposition of atmospheric sulphur and to the subsequent transformation of calcium carbonate into …
Effect of gypsum dihydrate on the kinetics of lime stone …
Download scientific diagram | Effect of gypsum dihydrate on the kinetics of lime stone strength: 1 – R c without additives; 2 – R c with 5 % CaSO 4 ·2H 2 O; 3 – R c /R b without additives ...
Gypsum: Properties, production and applications
Gypsum is a very soft mineral composed of calcium sulfate dihydrate and often occurs in nature as flattened and often twinned crystals and transparent cleavable …
Gypsum hydration: a theoretical and experimental study
Calcium sulphate dihydrate (CaSO4·2H2O or gypsum) is used widely as building material because of its excellent fire resistance, aesthetics, and low price. Hemihydrate occurs in …
Gypsum | Properties, Formation, Uses and Deposits
Gypsum, a naturally occurring mineral with the chemical formula CaSO4·2H2O, exhibits several important chemical properties that contribute to its versatility and usefulness in various applications. Here are some key chemical properties of gypsum: 1. Hydrated Structure:Gypsum is a hydrated …
Preparation of α-calcium sulfate hemihydrate from …
The bulk deposition of the industrial by-product gypsum causes severe environmental pollution and the increasing cost of land. How to reuse the huge amounts of by-product gypsum has become an urgent problem for the government. Since the last century, the preparation of α-HH with high-value added,
Exploring the role of calcium sulfate in supersulfated cement: …
A natural source of CS is gypsum (CaSO 4.2H 2 O), which is often used in SSC production [6], [9], [11], [18], [19], [20].Its anhydrous form (CaSO 4), anhydrite, is the most used since the dihydrate form has lower solubility while the hemihydrate form has higher solubility than anhydrite [21], [22].The main production of gypsum in Brazil is in the Northeast region …
Section 3 Environments of Subaqueous Gypsum Deposition
Evaporites were classified on the basis of their environmental relationships, particularly with respect to the under- and over-lying sedimentary sequences. ... "Section 3 Environments of Subaqueous Gypsum Deposition", Marine Evaporites, Walter E. Dean, B. Charlotte Schreiber, Walter E. Dean, Gerald M. Friedman, Robert J. Hite, Roy D. …
An efficient model for estimation of gypsum (calcium sulfate di-hydrate
Thermodynamic solubility of calcium sulfate di-hydrate (gypsum) plays a major role in many operations involved in oilfields and process industries. In this study, several solubility models were developed using the approaches including Multilayer Perceptron (MLP) networks, Radial Basis Function (RBF) networks, Least Squares …
Kinetics of the precipitation of calcium sulfate dihydrate in a
We further verified that a precipitous flux decline by deposition of gypsum crystals in the combined homogeneous and heterogeneous nucleation pathway was about 1.6 times delayed for the zwitterion-modified membrane compared to the control RO membrane. ... The kinetic of precipitation of calcium sulfate dihydrate (gypsum) in …
Effect of Different Evaporation Rates on Gypsum Habit: …
To recognize the effect of impurities on the gypsum habit, the impurity-free gypsum habit must be known. This is often reported in the literature by mixing calcium chloride dihydrate (CaCl 2 ·2H 2 O) or calcium nitrate (Ca(NO 3) 2) with sodium sulfate (Na 2 SO 4) to produce supersaturated solutions with respect to calcium sulfate dihydrate …
Exploring the feasibility of using fluidized bed homogeneous
The increasing salinity of water sources poses significant operational and environmental challenges, ... (basanite - Ca 2 H 2 O 9 S 2) [37], and calcium sulfate dihydrate (gypsum - CaSO 4 ·2H 2 O) [61], only CaSO 4 ·2H 2 O displays a stable peak signal [46]. ... effects of polypyrrole deposition protocols and activated carbon source ...
A simple correlation for predicting gypsum deposition from …
The predicted gypsum solubilities show excellent agreement with the experimental data for the temperature range of 25 to 80 °C and pressures up to 1,000 bar with NaCl concentration up to 5 M. The method is simple, compact, and reliable and can be applied to any environment where gypsum is expected to precipitate.
Analysis of emission of volatile organic compounds and …
Investment casting (IC), although the first examples of the use of this technique can be found many centuries ago, and significant development was recorded at the beginning of the twentieth century, is still a technology that is being developed and creates opportunities to implement new innovative solutions and material and …
INHIBITION OF GYPSUM SCALE FORMATION ON HEAT …
Experimental conditions and the gypsum growth data is summarized in Table 2. Typical curves for the calcium concentrations against time for gypsum deposition experi-ments on brass tubes in the absence of inhibitor (exp. 5, 8) are illustrated in Figure 2. It can be seen in Figure 2 that, following an induction period (~ 15 min), gypsum scale for-
Gypsum: a review of its role in the deterioration of
The deterioration of buildings and monuments by gypsum is the result of crystallization cycles of this salt. Although gypsum can dehydrate to a hemihydrate, the mineral bassanite, and to an anhydrate, the mineral anhydrite, this reaction occurs in nature on a geological time scale and therefore it is unlikely to occur when gypsum is found on …
The dehydration process of gypsum under high pressure
The effects of pressure on the dehydration of gypsum materials were investigated up to 633 K and 25 GPa by using Raman spectroscopy and synchrotron X …
Synthesis of large plate-like gypsum dihydrate from waste gypsum …
Arai 7 studied the deposition and growth of gypsum, and Yasue 1 has reported crystallographic results for producing gypsum dihydrate from waste gypsum board. ... The gypsum dihydrate seed crystal was synthesized by reaction of CaCl 2, Na 2 SO 4 and sodium citrate (Na 3 C 6 H 5 O 7) in aqueous solution. All reagents were …
Adsorption and solidification of cadmium by calcium sulfate dihydrate …
Its main component is calcium sulfate dihydrate (gypsum). In the present study, incorporation and adsorption of cadmium on gypsum in an aqueous environment have been investigated using dispersion-corrected density functional theory, and the effect of different vacancy defects on the adsorption and doping of Cd on gypsum was also studied.
Evaluation of atmospheric deposition on historic buildings …
1.. IntroductionAtmospheric deposition of gas and aerosols on building materials is one of the major causes of damage to stones and mortars of artistic interest 1, 2.The study of damage processes due to atmosphere/material interaction is of fundamental importance, for both a correct planning of conservation works on historic buildings and …
Two-Step Preparation of Quasi-Spherical α-Calcium Sulfate …
As the so1id waste generated from 1imestone gyp-sum wet desu1furization technique,the f1ue gas desu1-furization（FGD）gypsum,of which main content is ca1-cium su1fate dihydrate（CSD）,possesses the 1ow app1i-cation 1eve1 and uti1ization rate.As a consequence,the bu1k deposition of FGD gypsum have caused serious resource …
Effect of Different Evaporation Rates on Gypsum …
Gypsum (calcium sulfate dihydrate, CaSO 4 ·2H 2 O) is the most abundant sulfate mineral on Earth's surface and it is found in a wide range of natural and anthropogenic environments, ... hence contributing …
THE STABILITY OF GYPSUM AND ANHYDRITE
THE GEOLOGIC ENVIRONMENT by LEONARD STEVEN ROLNICK A.B., THE JOHNS HOPKINS UNIVERSITY (1950) ... Deposition from Sea Water . . . CHAPTER II. EXPERIMENTAL WORK . . ... Gypsum is composed of calcium sulphate dihydrate (CaSO4.2H20) and has the very useful property of being converted to the hemihydrate …
Synthesis of large plate-like gypsum dihydrate from waste gypsum …
Gypsum dihydrate can be converted to gypsum hemihydrate by heating at 180 ... Arai 7 studied the deposition and growth of gypsum, ... [15]. In order to save natural gypsum resource and reduce environmental pollution, many studies have used chemical gypsum [16], i.e. desulfurization gypsum [17], phosphogypsum [18] and …
Recycling, reusing and environmental safety of industrial by …
SG was a composite of anhydrous gypsum, hemihydrate gypsum and dihydrate gypsum. Table 1 illustrates that more than 80 % of the gypsum anhydrous and around 10 % of NaCl made up SG [42]. Hence, SG had the characterized of high salinity.
Gypsum: A review of its role in the deterioration of
The occurrence of gypsum and thaumasite was a result of the deposition by acidic air pollutants or biogenic sulfuric acid on structure facades, and deposition is commonly accompanied by the ...
Phase- and morphology-controlled crystallization of gypsum …
Fig. 1 shows the XRD pattern of FGD gypsum raw materials, which indicates that the main phase of FGD gypsum is calcium sulfate dihydrate. The morphology of FGD gypsum is given in Fig. 2. As illustrated in Fig. 2 a, the FGD gypsum has large particles with an average particle size distribution of about 60 μm.
A Critical Review of the Enhanced Recovery of Rare Earth …
Concerning the deposition form of REEs in PG, the possibilities are taht (i) REEs are structurally incorporated into the gypsum crystal lattice in the form of isomorphous substitution [36,37,38]; (ii) REEs precipitate as a separate phase such as oxides and sulfates trapped inside the gypsum crystal ; and (iii) REEs with phosphate …
The influence of cellulose derivatives on water structure in gypsum
Introduction. Gypsum plaster, CaSO 4 ·2H 2 O (also known as dihydrate) is one of the oldest building materials. It is used widely as indoor building material because of its numerous advantages: easy fabrication, low price, aesthetics, environmental friendliness, fire resistance, etc. [1].
Gypsum hemihydrate–cement blends to improve renderings …
It is favored by preliminary microcracks where deposition of ettringite crystals can occur: ... Fig. 3 shows SEM images of gypsum pastes exposed to external environment (Fig. 3 a) and internal environment (Fig. 3 b). ... The microstructure of β-HH-BFSC blends are more compact and a C–S–H film covers the gypsum dihydrate …