Ettringite precipitation

446-451. • Ettringite precipitation with Gibbsite recovery • Aluminum recovered from Ettringite sludge and recycled to front end of process • Recovered aluminum sludge sample 19 Mine Design, Operations, and Closure Conference: Short Course - Mine Water Treatment - Technologies, Case Studies, and Costs May 3, 2015 Elina Merta, VTT Technical Research Centre of Finland Ltd, P.O. Box 1000, FI-02044 VTT, Finland, elina.merta(at)vtt.fi Chemical precipitation techniques can be used to solve a number of problems in mine water treatment. Precipitation and co-precipitation are applicable for the removal of metals as hydroxides, carbonates or sulphides. Precipitation techniques are available also for the removal 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. When ettringite precipitation is used for waters with high sulphate concentration (>3000 mg/L), it may be economical to use traditional lime precipitation as a pre-treatment to remove some of the sulphate. After partial sulphate removal, a smaller dosage of the more expensive aluminium chemical is required for the ettringite precipitation step.

The results showed that ettringite precipitation is an effective and reliable method for sulphate removal. When ettringite precipitation is used for waters with high sulphate concentration (>3000 mg/L), it may be economical to use traditional lime precipitation as a pre-treatment to remove some of the sulphate. After partial sulphate removal, a smaller dosage of the more expensive aluminium chemical is required for the ettringite precipitation step. Ettringite •Ettringite is a complex hydrated calcium aluminum sulfate compound with this overall formula in nature: Ca 6 Al 2 (SO 4) 3 (OH) 12 ·26H 2 O •Theoretically, a precipitation process forming ettringite can drop dissolved sulfate levels to 50 mg/L or less under the right conditions In this study, the principles of chemical precipitation of sulfate which is based on the formation of ettringite, a double salt with the formula Ca3Al2O6.3CaSO(4).32H(2)O are evaluated. The aim of this research was to investigate sulphate removal from mine water by precipitation as ettringite (Ca6Al2(SO4)3(OH)12·26H2O) and the utilisation of the precipitate as a sorbent for arsenate removal.

The mine water sulphate concentration was reduced by 85-90% from the initial 1400 mg/L during ettringite precipitation depending on the treatment method. The precipitation conditions Chemical, physical and biological technologies for removal of sulphate from mine tailings pond water (8 g SO 4 2-/L) were investigated. Sulphate concentrations of approximately 1,400, 700, 350 and 20 mg/L were obtained using gypsum precipitation, and ettringite precipitation, biological sulphate reduction or reverse osmosis (RO) after gypsum pre-treatment, respectively.

Solution analyses quantified contaminant removal, and the collected solid was characterized using bulk and microprobe X-ray diffraction coupled with pair distribution function and microprobe X-ray 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- Sulfate Removal Technologies: A Review. By Mark Reinsel, Apex Engineering. 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. Continuous ettringite precipitation experiments for sulphate removal .

2010).
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Aygun and S. Dogan and M. E. Argun}, journal={Brazilian Journal of Chemical Engineering}, year={2018}, volume={35}, pages={969-976} } 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. the ettringite precipitation is a recognised method, appropriate to be implemented After each phase pH, EC and sulphate concentrations in industrial water treatment facilities.

CHUSTER . et al., 1996).
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Namely, under these conditions, the supersaturation level is the highest for ettringite which is then the more stable phase.