This process is based on the addition of aluminium hydroxide and lime at pH 11.5-12.0 resulting in precipitation of ettringite (Ca 3 Al 2 O 6 3CaSO 4 ⋅33H 2 O). By employing ettringite

Rather, the water for ettringite precipitation would be sourced from the excess water in the amorphous AH x forming. The presence of AFt and AH 3 was verified by XRD and FTIR characterization of the 2-d pastes, which exhibited some minor carbonation in the form of calcite (see Figure 3 ), observed to increase in intensity over time.

Precipitation of ettringite The most common image of sulfate attack is associated with the precipitation of ettringite, leading to expansion and cracking. Ettringite is a calcium sulfoaluminate hydrate with a composition of C 6ASS 3H 32: As such, the penetrating sulfates need to ﬁnd a source of aluminium and calcium with which to react. Alumin- Regarding the phase development during hydration, ettringite precipitation was identified as the dominant reaction in the first two hours. For both temperatures, the increasing ettringite content turned out to correlate very well with the loss of workability of the reacting cement paste. The reagent combines with soluble sulfate to form an ettringite precipitate. During ettringite precipitation, contaminants such as nitrate, chloride, fluoride, boron and 27 Mar 2021 Study on SO4 2- Removal with Ettringite Precipitation Approach in Wet. Desulfurization of Firing-Power Plant.

For monosulfate, the data for the two series for 45 Ca agreed well, both resulting in a reconstruction time around 500 days. Se hela listan på hindawi.com 2000-02-28 · ettringite could reduce the protection the air void system affords against freeze-thaw damage (see discussion of freeze-thaw resistance below). Ettringite formed by dissolution and recrystallization in void spaces and cracks is often referred to as “secondary ettringite.” Secondary ettringite is not detrimental to concrete performance. Chemical, physical and biological technologies for removal of sulphate from mine tailings pond water (8 g SO 4 2− /L) were investigated.

The formation of ettringite as a precipitate is another technique that can be used to treat mine-impacted water and has the capability of achieving sulphate concentrations that adhere to potable water and effluent discharge guidelines. Ettringite represents a group of acicular calcium aluminate hydrates (Damons and Petersen, 2002).

Sulphate control by ettringite precipitation in textile industry wastewaters In the present study, ettringite precipitation was theoretically and experimentally evaluated as a means of sulphate removal. The results showed that ettringite precipitation is an effective and reliable method for sulphate removal.

Ettringite precipitation Introduction. Ettringite precipitation (addition of lime and Al (OH) 3) can be used to remove sulphate and heavy metals. Description of the technology. Known processes for sulphate removal with ettringite precipitation contain the main unit Development stage.

20 May 2020 Ettringite precipitation was implemented as an alternative to lime precipitation to process sulfate-rich brine resulting from the NF operation. More

Sulfate concentrations in water have come under increasing scrutiny from regulatory authorities over the past two decades. In contrast to contaminants such as nitrate, arsenic, and heavy metals, sulfate has no primary standard for drinking water or aquatic life.

Ettringite precipitation Stage 3 is the heart of the Ettringite process and involves the addition of aluminium hydroxide to the saturated gypsum solution from stage 2.
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-C2S. -C4AF. - Gypsum (CSH2) is added to the clinker.

et al., 1996).
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Ettringite formation can also provide a polishing effect, allowing precipitation of difficult-to-remove metals such as chromium, arsenic, selenium and cadmium, often below their respective analytical detection limits. Boron, fluoride and up to 30 percent of the chloride and nitrate in water have also been removed.

The results showed that ettringite precipitation is an effective and reliable method for sulphate removal. Synthetically prepared samples which were simulated to total wastewaters originating from the textile industry (sulphate concentration of 0.06 M) and to dye bath E.-T. Tolonen, T. Hu, J. Rämö, U. Lassi, The removal of sulphate from mine water by precipitation as ettringite and the utilisation of the precipitate as a sorbent … The dissolution-precipitation rates obtained for ettringite and monosulfate, which represent a maximum rate for ion substitution processes with contaminants, can be used to distinguish this processes from comparably fast reactions, such as surface complexation and ion exchange, from ion substitution in sorption studies.

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DOI: 10.1590/0104-6632.20180353S20170528 Corpus ID: 104463417. STATISTICAL OPTIMIZATION OF ETTRINGITE PRECIPITATION IN LANDFILL LEACHATE @article{Aygun2018STATISTICALOO, title={STATISTICAL OPTIMIZATION OF ETTRINGITE PRECIPITATION IN LANDFILL LEACHATE}, author={A. Aygun and S. Dogan and M. E. Argun}, journal={Brazilian Journal of Chemical Engineering}, …

Description of the technology.