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 . 20/12/2017 5 Results: Batch tests for pilot design 0 1000 2000 3000 4000 5000 6000 7000 8000 0 50 100 150 SO 4 2-mg/l Time, minutes 0 500 1000 1500 2000 2500 0 10 20 30 40 SO 4 2-mg/l Time, minutes Gypsum precipitation Ettringite precipitation. Therefore, it can be assumed that the effect of ettringite precipitation on the rheological properties of the cement paste is of exponential order. With increasing ettringite content during hydration, the effect on the flow behavior becomes much larger. WO2017015678A2 PCT/ZA2016/050025 ZA2016050025W WO2017015678A2 WO 2017015678 A2 WO2017015678 A2 WO 2017015678A2 ZA 2016050025 W ZA2016050025 W ZA 2016050025W WO 2017015678 A2 WO2017015678 A2 WO 2017015678A2 Authority WO WIPO (PCT) Prior art keywords sulphate calcium ettringite stream gypsum Prior art date 2015-07-22 Application number … Ettringite precipitation Introduction.

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The following equation shows the basic chemical reaction to form ettringite Eq (1):) 1 ( A novel sulfate removal process via ettringite precipitation was developed by dissolving ettringite and recycling Al3+ under low pH condition. Effects of solid to liquid ratios, pH and temperature on ettringite dissolution, Al recovery and transformation of precipitates were investigated by batch experiments. The optimum condition for Al recovery is pH =3.0, suspended solid of 9.8 g/L and The ettringite process flow diagram used for simulation is illustrated in Figure 3. The process has three principal processing stages followed by a pH adjustment step.

2017-07-01 · The effect of Mg2+ on sulfate removal by ettringite precipitation was investigated, and the process was optimized in the absence and presence of Mg2+.

Gerätebau GmbH. A photograph of the plant in use with NaAlO 2 and lime and a close-up of the ettringite precipitates can be seen in Figures 1 and 2. The plant consists essentially of a raw water tank, a reactor tank followed by a (2016). Sulphate control by ettringite precipitation in textile industry wastewaters.

This is less than the drinking water guideline in Finland, which is 250 mg/L sulphate (Directive 98/83/EC). 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 ettringite precipitation is a well-known process and can be described as a standard method for sulphate removal from industrial wastewater at relatively small flow (S. CHUSTER .

2016), and judging from the lower solubility of ettringite,  Ettringite is a hydrous calcium aluminium sulfate mineral with formula: Ca6Al2( SO4)3(OH)12·26H2O. It is a colorless to yellow mineral crystallizing in the trigonal  chloride all remove sulfate as ettringite, with aluminum chloride removing sulfate to the lowest residual chemical precipitation processes, ettringite precipitation. Oct 1, 2016 Different versions of the precipitation as ettringite have been patented (Nevatalo et al., 2014, Ramsay, 2001). The basic idea is that the pH of the  react with calcium aluminate in the cement to form ettringite within the first few includes external elements of buildings or structures exposed to precipitation,. 1b, the formation of flake-like precipitates in the first minute precedes the significant precipitation of ettringite needles. Therefore, it is unlikely that they act as a  means of treating acid mine drainage is by forming a precipitate known as ettringite. Ettringite is a low solubility calcium hydrosulphoaluminate that is stable   wastcwater to precipitate the metal hydroxides, and lhe subsequent formation of ettringite to remove the calcium and sulphates.
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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. Known 2016-10-01 · Sulphate precipitation as ettringite is a modification of high pH lime precipitation (Geldenhuys et al., 2003, Tolonen et al., 2015). With precipitation as ettringite, mine water sulphate concentration can be reduced to less than 200 mg/L.

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. Ettringite precipitation process Batch ettringite precipitation studies using Reaction Calorimetry (RC) (Tommi Kaartinen, VTT) Thermodynamics and kinetics involved in the reactions related to the sulphate removal are determined Temperature, type of stirrer (anchor, … • 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 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 ettringite precipitation process (detailed below) resulted in excessive volumes of precipitate, as compared to other mine water sludges that the authors are familiar with. This paper thus aimed to examine (i) the influence of aluminium source on the properties … 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. In the present study, experiments were conducted to optimize sulfate removal efficiency with ettringite precipitation from landfill leachate using Response Surface Methodology (RSM) and Central Composite Design (CCD).
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The SAVMIN process is similar to the One of the main challenges in industrial wastewater treatment and recovery is the removal of sulfate, which usually coexists with Ca2+ and Mg2+. The effect of Mg2+ on sulfate removal by ettringite precipitation was investigated, and the process was optimized in the absence and presence of Mg2+. In the absence of Mg2+, the optimum conditions with sulfate removal of 99.7% were obtained at calcium-to-sulfate ratio of 3.20, aluminum-to-sulfate ratio of 1.25 and pH of 11.3 using response surface Ettringite was precipitated in the presence of TcO4-, IO3-, and/or CrO42-, known contaminants of concern to nuclear waste treatment, over pre-determined precipitation periods. Solution analyses quantified contaminant removal and the collected solid was characterized using bulk and microprobe XRD coupled with PDF and microprobe XRF more » analyses.

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ETTRINGITE. Portland Cement: Clinker Compounds: -C3A.