Ettringite precipitation

Ettringite precipitation was implemented as an alternative to lime precipitation to process sulfate-rich brine resulting from the NF operation. More than 93% of the sulfate ions were removed by ettringite precipitation, whereas lime precipitation removed less than 28% under the same conditions due to the difference in their solubility. The effect of Mg 2+ on sulfate removal by ettringite precipitation was investigated, and the process was optimized in the absence and presence of Mg 2+. In the absence of Mg 2+ , 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 methodology.

The Al-2 A novel sulfate removal process via ettringite precipitation was developed by dissolving ettringite and recycling Al 3+ 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. 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 . et al., 1996). This precipitation process is well-understood, reliable and can be easily controlled. The SAVMIN process is similar to the In the cement system, the presence of ettringite depends on the ratio of calcium sulfate to tri-calcium aluminate (C 3 A); when this ratio is low, ettringite forms during early hydration and then converts to the calcium aluminate monosulfate ( AFm phase or (Al 2 O 3 -Fe 2 O 3 -mono)).

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.

The results showed that ettringite precipitation is an effective and reliable method for sulphate removal. Ettringite precipitation (Equation (2)) has been shown to be an effective method for sulphate removal, as it can reduce sulphate concentration to 200 mg/L (Madzivire et al.

et al., 1996).

After the precipitation reaction is complete, the ettringite solids are separated from the feed water, filtered and thickened. Due to the high sulphate removal efficiencies of 85-90 % (Tolonen et al., 2016) and of over 95-98 % … The precipitation of boron in the form of an insoluble compound would be a very attractive method of treatment, but unfortunately, there is no known compound that quantitatively precipitates boron . The classical ettringite, having the chemical formula 6CaO·Al 2 O 3 ·3SO 3 ·32H 2 O [Ca 3 Al In the present study, ettringite precipitation was theoretically and experimentally evaluated as a means of sulphate removal.
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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. 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 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.

Synthetically prepared samples which were simulated to total wastewaters originating from the textile industry (sulphate concentration of 0.06 M) and to dye bath Ettringite precipitation based on formation of sulphate salts with low solubility can be used as a pretreatment method to overcome sulfate inhibition in anaerobic process. Calcium alumina-sulfate is commonly used to identify ettringite mineral. 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.
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Table 4 contains the test results for the solid reagents. It is surprising to find that products based on crystalline aluminium hydroxide (Hydrargillite), even at relatively high doses, are not appropriate for ettringite precipitation.

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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+.

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. 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.

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). The statistical analysis of the results showed that the operating parameters such as molar rates of Ca/ SO4 and Al/SO4, and pH had a significant effect on sulfate removal efficiency. 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.