Solubility of Tricalcium Aluminate in Synthetic Spent Bayer Liquor

A new kind of high strength cementitious material is made from phosphogypsum (PG), active carbon and fly-ash. Through the orthogonal research, it was showed that the calcination temperature, retention time, dosage of active carbon and fly ash on the compressive strength of cementitious binder are the most important. The result also showed that, in the conditions of temperature 1200°C, time retention 30 min, dosage of active carbon 10%, dosage of fly ash 5%, the compressive strength of the cementitious material for 3d and 28d could reach to 46.35MPa and 92.70MPa, the content of sulfur trioxide was 11.60% accordingly. A lot of active mineral materials, such as dicalcium silicate, tricalcium silicate, tricalcium aluminate were formed in the calcination. The C-S-H gel, calcium hydroxide and ettringite were found in 3d and 28d hydrates. It is found that the lime saturation ratio and silica modulus need to be control between 0.40~0.65 and 4~8 in order to produce high strength cementitious material.

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The Analysis of Bayer Liquor by SPME-GC-MS of Derivatized Organic Poisons

Proceedings ◽

10.3390/proceedings2020057101 ◽

2021 ◽

Vol 57 (1) ◽

pp. 101

Author(s):

Virgil Badescu ◽

Raluca Senin

Keyword(s):

Mass Spectrometry ◽

Gas Chromatography ◽

Gas Chromatography Mass Spectrometry ◽

Bayer Liquor ◽

Chromatography Mass Spectrometry ◽

Ms Analysis ◽

Silylating Agent

The aim of this article was the gas chromatography–mass spectrometry (GC-MS) analysis oforganic matter from a residual liquor sample (S.C. Alum S.A., Tulcea), extracted by the solid-phasemicroextraction method (SPMA) and derivatized with N-(tert-butyldimethylsilyl)-Nmethyltrifluoroacetamide(MTBSTFA) as the silylating agent. [...]

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Effect of Aluminum Sulfate on the Hydration of Tricalcium Aluminate

IOP Conference Series Earth and Environmental Science ◽

10.1088/1755-1315/719/2/022079 ◽

2021 ◽

Vol 719 (2) ◽

pp. 022079

Author(s):

Xiuyan Jing ◽

Yan Zhang ◽

Huaqing Liu ◽

Jialong Liu ◽

Sen Kong

Keyword(s):

Aluminum Sulfate ◽

Tricalcium Aluminate

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Sodium recovery from crystallization waste of Bayer liquor in alumina beneficiation

The Canadian Journal of Chemical Engineering ◽

10.1002/cjce.24126 ◽

2021 ◽

Author(s):

Rodrigo Aparecido Moreno ◽

Isabela Brandolis Alves Falconi ◽

Thamiris Auxiliadora Martins Gonçalves ◽

Roberto Seno Júnior ◽

Denise Crocce Romano Espinosa ◽

...

Keyword(s):

Bayer Liquor

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Effect of a Nitrite/Nitrate-Based Accelerator on the Strength Development and Hydrate Formation in Cold-Weather Cementitious Materials

Materials ◽

10.3390/ma14041006 ◽

2021 ◽

Vol 14 (4) ◽

pp. 1006

Author(s):

Akira Yoneyama ◽

Heesup Choi ◽

Masumi Inoue ◽

Jihoon Kim ◽

Myungkwan Lim ◽

...

Keyword(s):

Calcium Nitrate ◽

Hydrate Formation ◽

Frost Damage ◽

Cementitious Materials ◽

Heat Of Hydration ◽

Cold Weather ◽

Strength Development ◽

Hardened Cement ◽

Tricalcium Aluminate ◽

Nitrite Nitrate

Recently, there has been increased use of calcium-nitrite and calcium-nitrate as the main components of chloride- and alkali-free anti-freezing agents to promote concrete hydration in cold weather concreting. As the amount of nitrite/nitrate-based accelerators increases, the hydration of tricalcium aluminate (C3A phase) and tricalcium silicate (C3S phase) in cement is accelerated, thereby improving the early strength of cement and effectively preventing initial frost damage. Nitrite/nitrate-based accelerators are used in larger amounts than usual in low temperature areas below −10 °C. However, the correlation between the hydration process and strength development in concrete containing considerable nitrite/nitrate-based accelerators remains to be clearly identified. In this study, the hydrate composition (via X-ray diffraction and nuclear magnetic resonance), pore structures (via mercury intrusion porosimetry), and crystal form (via scanning electron microscopy) were determined, and investigations were performed to elucidate the effect of nitrite/nitrate-based accelerators on the initial strength development and hydrate formation of cement. Nitrite/nitrate-AFm (aluminate-ferret-monosulfate; AFm) was produced in addition to ettringite at the initial stage of hydration of cement by adding a nitrite/nitrate-based accelerator. The amount of the hydrates was attributed to an increase in the absolute amounts of NO2− and NO3− ions reacting with Al2O3 in the tricalcium aluminate (C3A phase). Further, by effectively filling the pores, it greatly contributed to the enhancement of the strength of the hardened cement product, and the degree of the contribution tended to increase with the amount of addition. On the other hand, in addition to the occurrence of cracks due to the release of a large amount of heat of hydration, the amount of expansion and contraction may increase, and it is considered necessary to adjust the amount used for each concrete work.

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Coupled Preparation of Ferronickel and Cementitious Material from Laterite Nickel Ores

Materials ◽

10.3390/ma13214992 ◽

2020 ◽

Vol 13 (21) ◽

pp. 4992

Author(s):

Ruimeng Shi ◽

Xiaoming Li ◽

Yaru Cui ◽

Junxue Zhao ◽

Chong Zou ◽

...

Keyword(s):

Direct Reduction ◽

Cementitious Materials ◽

Tricalcium Silicate ◽

Cementitious Material ◽

Raw Material ◽

Tricalcium Aluminate ◽

Thermodynamic Conditions ◽

Nickel Ores ◽

Main Components ◽

Factsage Software

Nickel slags can be produced through ferronickel preparation by the pyrometallurgical processing of laterite nickel ores; however, such techniques are underutilized at present, and serious environmental problems arise from the stockpiling of such nickel ores. In this study, a modification to the process of ferronickel preparation by the direct reduction of carbon bases in laterite nickel ores is proposed. The gangue from the ore is used as a raw material to prepare a cementitious material, with the main components of tricalcium silicate and tricalcium aluminate. By using FactSage software, thermodynamic calculations are performed to analyze the reduction of nickel and iron and the effect of reduction on the formation of tricalcium silicate and tricalcium aluminate. The feasibility of a coupled process to prepare ferronickel and cementitious materials by the direct reduction of laterite nickel ore and gangue calcination, respectively, is discussed under varying thermodynamic conditions. Different warming strategies are applied to experimentally verify the coupled reactions. The coupled preparation of ferronickel and cementitious materials with calcium silicate and calcium aluminate as the main phases in the same experimental process is realized.

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