In this film James Chubb looks at some of this extreme weather and explains General Ettringite Information. Help on Chemical Formula: Chemical Formula: Ca6Al2(SO4)3(OH)12•26(H2O). Help on Composition: Composition: Molecular Dec 27, 2019 Snow. Sleet.
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The results showed that ettringite precipitation is an effective and 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. Synthetically prepared samples which were simulated to total wastewaters originating from the textile industry (sulphate concentration of 0.06 M) and to dye bath effluent (sulphate concentration of 0.22 M) were subjected to ettringite precipitation using the Ettringite decomposition is the reverse of ettringite formation and forms the gibbsite for recycle. The solids formed in Reactor 1 are not separated and are transferred to the gypsum precipitation reactor, Reactor 2, where lime is added. A novel sulfate removal process via ettringite precipitation was developed by dissolving ettringite and recycling Al3+ under low pH condition.
The experimental study of the CaO-SiO2-Al2O 3-SO3-H2O system clarified the Sulphate removal from mine water by precipitation as ettringite by newly developed electrochemical aluminium dosing method. Emma-Tuulia Nurmesniemi* mental results reveal that citric acid works as an inhibitor of ettringite's formation leading to the precipitation of monosulfate and gypsum; the ettringite surface Sulphate concentrations of approximately 1,400, 700, 350 and 20 mg/L were obtained using gypsum precipitation, and ettringite precipitation, biological In excess of 95% of the Se and B in solutions spiked with various concentrations of these elements has been removed by precipitation of ettringite. Ettringites The evaluation of chemical precipitation for sulfate removal such as gypsum and ettringite formation as well as the use of membrane filtration and the decision others like calcium hydroxide and ettringite can precipitate in the water phase.
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. An Aspen computer simulation. Ettringite precipitation can be considered as responsible for these expansions.
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The determined reconstruction time for ettringite lay within 1.2-4 years, which resulted in a dissolution-precipitation rate of 10 À 12.2 to 10 À 11.5 mol m À 2 days À 1 . 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).
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 start of ettringite precipitation is defined as the moment when conductivity starts to drop. The temperature was kept at 25 °C and experiments were conducted in a 400 mL-capacity jacketed glass reactor containing a Nalgene surface. The stirring rate, with a bar magnet, was taken equal to 400 rpm.
The start of ettringite precipitation is defined as the moment when conductivity starts to drop. The temperature was kept at 25 °C and experiments were conducted in a 400 mL-capacity jacketed glass reactor containing a Nalgene surface. The stirring rate, with a bar magnet, was taken equal to 400 rpm. 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 .
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. Worldwide, two commercial processes with ettringite 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 Request PDF | On Sep 1, 2019, Emma-Tuulia Nurmesniemi and others published Ettringite precipitation from mine water with electrochemical aluminium dosage | Find, read and cite all the research you 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.
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. 2016-10-01 · 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 were also simulated with MINEQL + software, and the computational results were compared with the experimental results. 2020-01-01 · The precipitation rates of ettringite R total determined in all the experiments reported in this work can therefore be expressed as the sum of several contributions: the homogeneous nucleation rate R homo depending only on β, the secondary nucleation rate R sec depending on β, the number of crystals N and their surface S and the growth rate R growth depending on β and S. (11) R total = R
The aluminium precipitation with the simultaneous formation of ettringite was chosen for laboratory testing as it is appropriate when the concentrations of sulphates have to be reduced-up to 300
Chemical precipitation. Sulphide precipitation; Precipitation with barium salts; Ettringite precipitation; Iron co-precipitation; Ion exchange; Membrane processes; Sulphate reduction in reactors; Treatment/disposal of water treatment residues; Passive treatment technologies. Aerobic constructed wetlands; Anaerobic constructed compost wetlands
In the present study, ettringite precipitation was theoretically and experimentally evaluated as a means of sulphate removal.
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 Chemical, physical and biological technologies for removal of sulphate from mine tailings pond water (8 g SO 4 2-/L) were investigated.
The precipitation conditions were also simulated with MINEQL + software, and the computational results were compared with the experimental results. 2017-07-01 · As a sulfate salt with lower solubility (pK sp = 43.13) (Almasri et al., 2015) than that of CaSO 4, ettringite [Ca 6 Al 2 (OH) 12 (SO 4) 3 ·26H 2 O] is a modification of high pH lime precipitation, and is considered as a promising way for sulfate removal (Kabdaşlı et al., 2016, Tolonen et al., 2016).
Ettringite represents a group of acicular calcium aluminate hydrates (Damons and Petersen, 2002).