Factors affecting the precipitation of pure calcium carbonate during the direct aqueous carbonation of flue gas desulfurization gypsum

Abstract Reactivity of various calcium carbonate samples for flue gas desulfurization was tested. Two groups of CaCO3 samples were considered; natural limestone containing calcite phase dominantly and samples prepared by the conversion of gypsum with ammonium and carbon dioxide (precipitated CaCO3) containing different amounts of calcite, aragonite and vaterite. Reactivity of precipitated calcium carbonate depends primarily on the particle size, similarly as in case of industrial samples. The initial reaction rate was comparable with the industrial limestones for samples with the average particle size lower than 15 μm. However, the conversion of laboratory samples was significantly higher after 5 min of the reaction. Phase composition of the precipitated calcium carbonate has a minor but noticeable impact on the reactivity. The presence of vaterite slightly increased the reactivity, which is in accordance with its lower compact structure in comparison with calcite and aragonite. Unexpected effect of the increased content of aragonite, which is the most compact phase in comparison with calcite and vaterite, was observed. If calcium carbonate contains up to approximately 30 % of aragonite the reactivity increases, which can be explained by the SEM pictures showing agglomerate composition with relatively high specific surface. At higher contents of aragonite, the reactivity decreases. All the obtained results proved the suitability of precipitated CaCO3 prepared from flue gas desulfurization gypsum to be recycled in the flue gas desulfurization process.

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Study on Particles Wetted by the Calcium-Based Slurries and the Slurries Viscosity with the Wetting Agents

The Open Chemical Engineering Journal ◽

10.2174/1874123101509010103 ◽

2015 ◽

Vol 9 (1) ◽

pp. 103-108

Author(s):

Xiaowen Hao ◽

Zhijun Zhang ◽

Ran Liu

Keyword(s):

Flue Gas ◽

Sessile Drop ◽

High Viscosity ◽

Sessile Drop Method ◽

Flue Gas Desulfurization ◽

Factors Affecting ◽

Two Factors ◽

Wetting Agents ◽

Wet Particles ◽

Pm2.5 Concentration

Chemical agglomeration can reduce the particulates (including PM2.5) concentration emitted from fly ash particulates and the wet flue gas desulfurization (WFGD) system. However, the calcium-based slurries affect the regulation of agglomeration compared to water, in particular, the wettability of the particulates and the viscosity of the calciumbased slurry. The wettability and the viscosity are the important factors affecting agglomeration, conversely. This manuscript studied the two factors affecting the calcium-based slurries. The sessile drop method was used to measure the contact angle. Four kinds of calcium-based slurries (CaCO3, CaSO3, CaSO4, Ca(OH)2) respectively were mixed with five kinds of wetting agents’ wet particles, and the wetting regulation was studied. The viscometer was used to measure the viscosity of the calcium-based slurry with the wetting agents, and the variation of the viscosity was analyzed as well. The results showed that the smaller the particle size was, the more it is difficult to be wet, and the wetting agents could enhance the wettability greatly, but the effect was related to the properties of the calcium-based material and the wetting agents. There were variable viscosities of different calcium-based slurries after adding the wetting agents. Overall, the Compound No. 3 had the optimal qualities in improving particle wettability and maintaining the calcium-based slurry with a high viscosity. Therefore, the Compound No. 3 is considered the optimal in facilitating chemical agglomeration.

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URANUS 52N

Alloy Digest ◽

10.31399/asm.ad.ss0566 ◽

1994 ◽

Vol 43 (5) ◽

Keyword(s):

Stainless Steel ◽

Corrosion Resistance ◽

High Temperature ◽

Flue Gas ◽

Crevice Corrosion ◽

Heat Treating ◽

Flue Gas Desulfurization ◽

Temperature Performance ◽

Aisi Type ◽

Better Than

Abstract URANUS 52N is a nitrogen-alloyed duplex stainless steel improved in stress-corrosion cracking resistance and with pitting and crevice corrosion resistance better than AISI Type 317L. Applications include handling phosphoric acid contaminated with chlorides and in flue gas desulfurization scrubbers. This datasheet provides information on composition, physical properties, and tensile properties. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, and joining. Filing Code: SS-566. Producer or source: Creusot-Marrel.

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AL 4565 ALLOY

Alloy Digest ◽

10.31399/asm.ad.ss0906 ◽

2004 ◽

Vol 53 (8) ◽

Keyword(s):

Fracture Toughness ◽

Corrosion Resistance ◽

High Temperature ◽

High Resistance ◽

Flue Gas ◽

Heat Treating ◽

Flue Gas Desulfurization ◽

High Nitrogen ◽

Temperature Performance ◽

High Level

Abstract AL 4565 alloy has a high level of austenitizers, which provides the microstructure with a high resistance to sigma formation during welding. The high nitrogen also gives the alloy superior strength among the austenitics. Applications include flue gas desulfurization and handling seawater. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as fracture toughness. It also includes information on high temperature performance and corrosion resistance as well as heat treating and joining. Filing Code: SS-906. Producer or source: Allegheny Ludlum Corporation.

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