Hyperpressed Calcium Sulfate Dihydrate Structure

2014 ◽  
Vol 1025-1026 ◽  
pp. 820-823 ◽  
Author(s):  
Victoria Petropavlovskaya ◽  
Аleksandr Buryanov ◽  
Тatyana Novichenkova
Keyword(s):  
Calcium Sulfate ◽  
Raw Materials ◽  
Disperse Systems ◽  
Calcium Sulfate Dihydrate ◽  
Ceramic Manufacture ◽  
The Way

In article the method of formation of structure of disperse systems on a basis of calcium sulfate dihydrate is described. It is based on various concentration of a solution at a surface of particles of the various size. As raw materials it was used calcium sulfate dihydrate − a withdrawal of ceramic manufacture. The picked up structure of particles in the sizes was applied. For acknowledgement of the offered method following researches have been carried out on: solubilities of powders, to deformations of a raw mix, durability of structure. The way of reception of gypsum products allows to simplify technology. Energy expenses decrease. Burning is excluded and the grinding is reduced.

scholarly journals Mechanism of gypsum hardening

2018 ◽  
Vol 196 ◽  
pp. 04096 ◽  
Author(s):  
Victoria Petropavlovskaya ◽  
Tatiana Novichenkova ◽  
Andrey Pustovgar ◽  
Aleksandr Buryanov ◽  
Kirill Petropavlovskii
Keyword(s):  
Calcium Sulfate ◽  
Raw Material ◽  
Pilot Studies ◽  
Industry Waste ◽  
Calcium Sulfate Dihydrate ◽  
The Way

In the present work the receiving of gypsum products on the basis of a calcium sulfate dihydrate is described. As a raw material, the calcium sulfate dihydrate in the form of industry waste was used. This research offers the mechanism of un hydration hardening of monomineral bindings, including gypsum. The mechanism is based on interaction of particles of the different size in the conditions of supersaturation when pressing. Under the corresponding conditions in system of a dihydrate crystallizational contacts are formed. The offered mechanism is confirmed with pilot studies. Researches of solubility of powders, to deformations of raw mix, strength, density and other characteristics of structure are conducted. Strength reaches to 74 MPa. The way allows to simplify technology of receiving gypsum products. Expenses of energy decrease. Burn is excluded and the grinding is reduced. Thus the offered of un hydration hardening of monomineral binders has high innovative appeal.

scholarly journals Influence of addition of calcium sulfate dihydrate on drying of autoclaved aerated concrete

2017 ◽  
Vol 7 (1) ◽  
pp. 273-278 ◽  
Author(s):  
Dorota Małaszkiewicz ◽  
Jacek Chojnowski
Keyword(s):  
Calcium Sulfate ◽  
Hydrothermal Reaction ◽  
Raw Materials ◽  
Capillary Rise ◽  
Initial Moisture Content ◽  
Material Structure ◽  
Performance Parameters ◽  
Autoclaved Aerated Concrete ◽  
Calcium Sulfate Dihydrate ◽  
Aerated Concrete

AbstractThe quality of the autoclaved aerated concrete (AAC) strongly depends on the chemical composition of the raw materials, as well as on the process of the hydrothermal reaction during autoclaving. Performance parameters depend on material structure: fine micron-scale matrix porosity generated by the packing of thin tobermorite plates and coarse aeration pores arising from the foaming of wet mix. In this study the binder varied in calcium sulfate dihydrate (CaSO4⋅2H2O) content. Five series of AAC specimens were produced, with gypsum content 0; 0.55; 1.15; 2.3 and 3.5% of dry mass respectively. AAC units were produced in UNIPOL technology. The study presents experimental results of AAC moisture stabilization. The initial moisture content was determined directly after autoclaving. Slower drying process was observed for samples containing over 2% of gypsum. Whereas other performance parameters, compressive and tensile strength, as well as water absorption and capillary rise, were significantly better comparing to the reference AAC samples.

Preparation of anhydrite from eggshell via pyrolysis

2018 ◽  
Vol 7 (2) ◽  
pp. 139-146 ◽  
Author(s):  
Nuchnapa Tangboriboon ◽  
Wanitcha Unjan ◽  
Watchara Sangwan ◽  
Anuvat Sirivat
Keyword(s):  
Calcium Sulfate ◽  
Pore Diameter ◽  
Raw Materials ◽  
Raw Material ◽  
X Ray ◽  
Anhydrous Calcium Sulfate ◽  
Calcium Sulfate Dihydrate ◽  
Thermal Analyzer ◽  
Infrared Spectrometer ◽  
Calcium Sulfate Hemihydrate

AbstractCalcium sulfate dihydrate (CaSO4·2H2O) was prepared from the chemical reaction between calcium carbonate from duck eggshell and sulfuric acid at 25°C. The CaSO4·2H2O was dried in an oven at 110°C and transformed into calcium sulfate hemihydrate or plaster of Paris (CaSO4·0.5H2O). The CaSO4·0.5H2O was calcined at 700, 800 and 900°C and transformed into anhydrite or anhydrous calcium sulfate (CaSO4). The raw material used in this research was the duck eggshell, the waste eggshell generated from food processing industries. The obtained anhydrous calcium sulfate or anhydrite has true density, color, specific surface area, pore diameter and particle size equal to 2.95 g/cm3, white powder, 3.57 m2/g, 96.98 Å and 3.983 μm, respectively. In addition, other characteristics, microstructures, phase transformation and physical properties of raw materials and calcium sulfates were investigated and reported here using X-ray fluorescencemeter, Fourier transform infrared spectrometer, differential thermal analyzer, thermogravimetric analysis, scanning electron microscope, X-ray diffractometer, pycnometer method and Brunauer-Emmett-Teller.

scholarly journals Simple superphosphate by two-stage acid treatment of phosphate raw materials

2021 ◽  
Vol 939 (1) ◽  
pp. 012057
Author(s):  
D Sherkuziev
Keyword(s):  
Phosphoric Acid ◽  
Flow Rate ◽  
Acid Treatment ◽  
Calcium Sulfate ◽  
Raw Materials ◽  
Production Cycle ◽  
Second Stage ◽  
Additional Input ◽  
Concentrated Solution ◽  
Two Stages

Abstract The distinguishing feature of the proposed flow method before the classical (chamber) method is that the entire production cycle of natural phosphate processing is carried out in two stages. At the first stage, the phosphorite is treated with a stoichiometric flow rate of concentrated sulphuric acid (at least 93%), under conditions of complete decomposition of phosphorite to form phosphoric acid and crystals of anhydrite (calcium sulfate). The reaction temperature is 122 °C. In the second stage, the resulting concentrated solution of phosphoric acid in a mixture with sulphur is involved in a reaction with an additional input of phosphorite, which is the basis for the mechanism of chemical formation of monocalciumphosphate and granulation of superphosphate mass. The processes for neutralizing phosphoric acid on monocalciumphosphate and for granulating the product by coagulation are combined in one apparatus. The drying stage of the product is excluded from the scheme.

scholarly journals Obtaining artificial carnallites from magnesium chloride brines

2020 ◽  
Vol 56 (2) ◽  
pp. 229-234
Author(s):  
V. V. Shevchuk ◽  
T. N. Potkina ◽  
A. I. Vaitenka ◽  
O. V. Smetanina
Keyword(s):  
Calcium Chloride ◽  
Magnesium Chloride ◽  
Calcium Sulfate ◽  
Raw Materials ◽  
Potassium Sulfate ◽  
Sulfate Ions ◽  
Chloride Solutions ◽  
Excess Concentration ◽  
Almost All ◽  
Complete Precipitation

The excess of magnesium chloride brines is formed during the polymineral ores processing in order to obtain potassium sulfate. One way to regenerate such brines is to produce artificial carnallite. It is necessary to purify these brines from sulfates for their further use as raw materials for the artificial carnallite production. In this work, the process of desulfurization of magnesium chloride brines with a solution of calcium chloride is studied. The temperature and the processing time, the magnesium chloride solutions concentration and the consumption of desulfurizing agent (calcium chloride) influence on the degree of magnesium chloride solutions purification from sulfate ions was determined. It has been established that almost all sulfate ions interact with calcium ion in 15 minutes and the desulfurization degree reaches 98,08 %. The increase in duration of the suspension mixing is necessary in order to establish equilibrium in the system and relieve the supersaturation in the solution. It has been shown that with increasing solutions saturation with MgCl2, the degree of the magnesium chloride brines purification from SO4 2– ion increases. Complete precipitation of calcium sulfate requires a certain excess concentration of calcium chloride.

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