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Wyszukujesz frazę "calcium hemihydrate" wg kryterium: Temat


Wyświetlanie 1-3 z 3
Tytuł:
Studies on the transformation of calcium sulphate dihydrate to hemihydrate in the wet process phosphoric acid production
Autorzy:
Grzmil, B.
Kuc, B.
Żurek, O.
Kubiak, K.
Powiązania:
https://bibliotekanauki.pl/articles/779732.pdf
Data publikacji:
2012
Wydawca:
Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Tematy:
kwas fosforowy
fosfogips
transformacja
półhydrat wapnia
wet process phosphoric acid
phosphogypsum
transformation
calcium hemihydrate
Opis:
The influence of the process temperature from 85°C to 95°C, the content of phosphates and sulphates in the wet process phosphoric acid (about 22-36 wt% P2O5 and about 2-9 wt% SO42-) and the addition of ?CaSO4ź0.5H2O crystallization nuclei (from 10% to 50% in relation to CaSO4ź2H2O) on the transformation of calcium sulphate dihydrate to hemihydrate has been determined. The wet process phosphoric acid and phosphogypsum from the industrial plant was utilized. They were produced by reacting sulphuric acid with phosphate rock (Tunisia) in the DH-process. The X-ray diffraction analysis was used to determine the phase composition and fractions of various forms of calcium sulphates in the samples and the degree of conversion of CaSO4ź2H2O to ?CaSO4ź0.5H2O and CaSO4. It was found that the transformation of CaSO4ź2H2O to ?CaSO4ź0.5H2O should be carried out in the presence of ?CaSO4ź0.5H2O crystallization nuclei as an additive (in the amount of 20% in relation to CaSO4ź2H2O), at temperatures 90š2°C, in the wet process phosphoric acid containing the sulphates and phosphates in the range of 4š1 wt% and 27š1 wt%, respectively.
Źródło:
Polish Journal of Chemical Technology; 2012, 14, 2; 80-87
1509-8117
1899-4741
Pojawia się w:
Polish Journal of Chemical Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Preparation of α-calcium sulfate hemihydrate from industrial by-product gypsum: a review
Autorzy:
Guan, Qingjun
Sui, Ying
Zhang, Fang
Yu, Weijian
Bo, Yongjie
Wang, Ping
Peng, Wenqing
Jin, Jiao
Powiązania:
https://bibliotekanauki.pl/articles/1448527.pdf
Data publikacji:
2021
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
α-calcium sulfate hemihydrate
industrial by-product gypsum
FGD gypsum
phosphogypsum
preparation method
Opis:
In recent years, the massive accumulation of industrial by-product gypsum, especially flue gas desulfurization (FGD) gypsum and phosphogypsum (PG), not only encroaches on lands but also causes serious environmental pollution. 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. Hitherto the preparation methods of α-HH from industrial by-product gypsum mainly include the autoclave process, salt/acid solution process, or alcohol-water solution process. Thereinto, the autoclave process is the only method to realize industrialization. In order to solve the high energy consumption and unfavorable continuous operation of the autoclave process, researchers suggested alternative approaches, such as salt/acid solution process and alcohol-water solution process. However, these methods are basically in the laboratory stage or pilot scale test at present. Compared with FGD gypsum, the utilization rate of PG with a larger emission is very low owing to the high impurity content. And combining the preparation of α-HH with the recovery of valuable impurities from PG seems a promising way to solve the bulk deposition of PG.
Źródło:
Physicochemical Problems of Mineral Processing; 2021, 57, 1; 168-181
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Determination of the calcium sulfate hemihydrate content by regression analysis using the initial setting time
Autorzy:
Li, Bing
Powiązania:
https://bibliotekanauki.pl/articles/231074.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
gips
modyfikacja
czas wiązania
analiza regresji
hemihydrat siarczanu wapnia
gypsum
modification
setting time
regression analysis
calcium sulfate hemihydrate
Opis:
In this paper, we randomly select 75 sets data of calcium sulfate hemihydrate (CSH) content and initial setting time, and the traditional test method of CSH and analyses initial setting time was used by complexometric titration. So the close relationship between them was studied in depth, which classification fitting data to be analyzed by regression analysis. The result shows that this regression analysis method can accurately determine CSH content in modified industrial by-product gypsum. The determination method has the advantages of simplification and rapid operation. As well as, the XRF quantitative analytical method was used to test the CSH content, which verified the accuracy of regression analysis method. The results also show that this method has high accuracy, and can simplify the traditional experimental process. The method developed is easier and more convenient and has broad prospects in application.
Źródło:
Archives of Civil Engineering; 2020, 66, 2; 421-437
1230-2945
Pojawia się w:
Archives of Civil Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-3 z 3

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