The present study is focused on clarifying the influence of waste gypsum (WG) in replacing natural gypsum (NG) in the production of ordinary Portland cement (OPC). WG taken from slip casting moulds in a ceramic factory was formed from the hydration of plaster of paris. Clinker and 35 wt% of WG was ground in a laboratory ball mill to produce ...
What is claimed is: 1. A process for producing an accelerator for hemihydrate gypsum comprising comminuting gypsum board to a particle size of about 100 mesh, and thereafter finegrinding the resulting comminuted material in a ball mill to have an average particle size of about 1 micron and to have a specific surface area of about 100,000130,000 square centimeters per gram.
Phosphogypsum (PG) is a byproduct generated from the phosphorus fertilizer industry (phosphoric acid production). PG is similar to natural gypsum, but there are some differences, of which it contains some impurities such as watersoluble phosphate (P 2 O 5 ), watersoluble fluoride (F −) and P 2 O 5 substituted in the gypsum crystal lattice.
The applications of wastederived fuel from paper mills in industrial boilers benefit the reduction of carbon emissions. However, the cocombustion of wastederived fuel and coal causes significant changes in the characteristics of the ash and brings about the need to find possible means of the utilization of the ash produced. In this work fly, ash samples were collected from circulating ...
The purified FGD gypsum, approximately g, was first wetmilled at a rate of 300 rpm for 240 min (polyethylene bottle, ZrO 2 medium) in a ball mill (QM3SP2, Nanjing University Instrument Co., China), while maintaining the mass ratio of purified FGD gypsum to distilled water at 1:1. After ball milling, the slurry was transferred into a doublewalled jacket autoclave (CJK1, Weihai Newera ...
Gypsum is a crystalline form of hydrated calcium sulfate (CaSO 4 ·2H 2 0) generally used in cements and plasters in the construction industry, though also in paints, fertilizers, medicines, papers, and textiles. For use in these materials, gypsum must be ground finely (< 100 μm), if not ultrafinely (< 10 μm), for which ball mills are most effective.
In the study, raw materials including clinker, gypsum, pozzolan were separately milled on a ball mill (the ball mill size: φ500 mm × L500 mm, productivity: 5 kg / grinding time) to achieve the ...
The use of phosphogypsum to prepare phosphorus building gypsum (PBG) is of great value to the resource utilization of phosphogypsum. In this study, PBG was ballmilled to obtain phosphorus building gypsum with good performance, which can meet the requirements of the Chinese standards for firstclass building gypsum. Meanwhile, the changes of net slurry physical properties, mechanical ...
Mining of native sulfur deposits is accomplished by the Frasch process, which uses superheated water to melt the sulfur so that it can be pumped to the surface. Sulfur is used in petroleum refining and in the preparation of fertilizer and chemicals. Texas is one of the nation's leading producers of sulfur.
The hemihydrate gypsum dissolves until it forms a saturated solution. This saturated solution of hemihydrate is supersaturated with respect to dihydrate gypsum, and so the latter crystallizes out of the solution at suitable nucleation sites. ... Ball mill accelerator (BMA) 1 g Paper pulp 2 g ing agent 4 mL water 165 mL Sodium ...
The hydration of an anhydrite of gypsum (CaSO ) in a ball mill was studied as a function of time and amount of gypsum formed at different intervals of time was determined by weight loss method and powder Xray diffraction technique. Specific surface area at different time intervals was determined by LASER granulometric method.
At the end of the ball mill grinding operation, the material is ready for use as an accelerator. It is added directly to hemihydrate gypsum or a slurry of hemihydrate gypsum. test procedure is described in the Journal of American Chemical Society 59,1553 (1937); 60,309 (1938); and 62,1723 (1940).
The calcium sulphate dihydrate gypsum (CaSO 4 ·2H 2 O) is the most common sulphate evaporite mineral on our planet evaporites play an important role in Earth's sulphur cycle and are ...
Mechanical activation was carried out in a ball mill. Two types of samples were formed: one type with nonmilled mixtures and the second type with milled mixtures. ... Singh found out that soluble phosphates H 3 PO 4, Ca(H 2 PO 4) 2, and fluorides (NaF) change hemihydrate gypsum crystal morphology (from needle to prismatic, rhombic and lath ...
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Korean J. of Chem. Eng., 13(6), 585505 (1996) MODELING AND SIMULATION OF A WET HEMIHYDRATE PHOSPHORIC ACID PROCESS Hyun Jun Cho, YeongKoo Yeo*, Woo Hyun Park* and Bong Kyu Moon* Dept. of Chem. Eng., Hanyang University, Seoul 133791, Korea *Namhae Chemical Co., Nakpodong, Yeochun 555250, Korea (Received 8 April 1996 9accepted 15 October 1996) A b s t r a c t The wet hemihydrate phosphoric ...
The proportions of gypsum, hemihydrate and anhydrite are individually optimized for each type of cement [7]. ... Typical ball mills, which are currently used predominantly for cement grinding in Germany, reach temperatures of up to 125 °C in the mill exhaust gas. Experience has shown that these grinding chamber temperatures facilitate complete ...
Dry grinding of gypsum (CaSO 4 ·2H 2 O) with hydrated minerals, such as talc, kaolinite or montmorillonite as an additive was conducted in a planetary ball mill in order to investigate the transformation of gypsum into its hemihydrate form (CaSO 4 · 1 2 H 2 O).This transformation of gypsum is accelarated by grinding and by the presence of hydrated minerals
Section snippets Chemicals and materials. Analytical grade CuCl 2 ·2H 2 O and H 2 SO 4 were purchased from the Luoyang Chemical Reagent Co. (Luoyang, China) while the FGD gypsum was supplied by a power plant in Henan Province, China. This gypsum was purified by screening, ballmilling, acid treatment, flotation and a second ballmilling (Wang, Yang, Wang, Liu, Zhu, 2012; Wang et al., 2014).
For high gypsum board line speed and thus high production capacity utilization the use of high concentrations of gypsumbased ball mill accelerator (BMA) are common practice. ... Gypsum binder used for gypsum board production is plaster, also known as stucco, with betacalcium sulphate hemihydrate as the main gypsum phase. Normal plaster needs ...
material because of its excellent fire resistance, aesthetics, and low price. Hemihydrate occurs in two formations of α and βtype. Among them βhemihydrate is mainly used to produce gypsum plasterboard since the hydration product of the αhemihydrate is too brittle to be used as building material /10/. This article addresses the hydration of
According to Fig. 2, the detailed process of dehydration of dihydrate into hemihydrate was as follows: Firstly, the dry gypsum blocks were crushed into coarse particles using a jaw crusher, then, each time approximate 20 L of the coarse particles were grinding for 5 min through a ball that, the 2 cm thick calcium sulfate dihydrate powders in an iron plate were calcined in an oven at ...
Table The amount of dihydrate, hemihydrate and anhydrite in natural gypsum and waste gypsum 70 Table Particle size of clinker, natural gypsum and waste gypsum 71 ... Figure Laboratory ball mill, PASSCALL. 45 Figure Flowchart for characterization of raw materials 47 Figure Siemens D5000, XRD instrument 48 ...
The hydration of an anhydrite of gypsum () in a ball mill was studied as a function of time and temperature. The amount of gypsum formed at different intervals of time was determined by ...
the sum of the roller mill and kettle calciner output rates. k References 45,11,1314. Emission factors based on the kettle and the hot pit do not apply to batch kettle calciners. mReferences 3,6,10. n References 3,6,9. p References 9,15. As used here, an impact mill is a process unit used to dry, grind, and calcine gypsum simultaneously. q ...
On heating at 150 °C, gypsum loses about % of water of crystallization in the form of steam, resulting in the formation of βhemihydrate plaster which contains about % of the remaining water of crystallization. The plaster is then ground in a ball mill to a fineness passing 150 micron IS sieve. Superplasticizers
The αhemihydrate gypsum (αHH) has the advantages of high strength, lightweight, has no pollution, and good biocompatibility 28, 29. ... According to the preliminary exploration test on ball mill material ball ratio and water addition, the material to ball ratio of the ball mill was 3:1, and the water volume was 500 ml, and the effect on the ...
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