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THE RECOVERY OF SULPHUR FROM WASTE GYPSUM by ... 2.3.3 Biological sulphate reduction process.....12 2.4 THERMAL ANALYSIS ... Figure 4.1 Process flow diagram for the sulphur recovery process.....59 Figure 5.1 The 5 ℓ jacketed, pressurised & continuously stirred reactor used ...
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Techniques of this general type are mentioned in the Burwell U.S. Pat. No. 2,740,691. This patent teaches the reduction of gypsum with a reducing gas stream at temperatures of from 890 C. to about 1,000 C. Burwell's process results in the recovery of the sulfur values from the gypsum essentially in the form of hydrogen sulfide.
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The process evaluated consists of the following stages: reduction of gypsum to calcium sulphide; stripping of the sulphide with CO2 gas and the production of sulphur. Thermal reduction study showed that gypsum can be reduced to CaS with activated carbon in a tube …
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The aim of this investigation was to evaluate a process for converting waste gypsum into sulphur and calcium carbonate. The process evaluated consisted of the following stages: reduction of gypsum to calcium sulphide; H2S-stripping and sulphur production. Thermal reduction showed that gypsum could be reduced to CaS with activated carbon in a ...
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May 17, 2017 This process is known as the citrate process and was developed as a result of research on the recovery of sulfur from gypsum. Briefly, the recovery of sulfur from gypsum involves reduction roasting of gypsum with coal or natural gas to form calcium sulfide.
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A combined chemical and biological process for the recycling of flue gas desulfurization (FGD) gypsum into calcium carbonate and elemental sulfur is demonstrated. In this process, a mixed culture of sulfate-reducing bacteria (SRB) utilizes inexpensive carbon sources, such as sewage digest or synthesis gas, to reduce FGD gypsum to hydrogen sulfide. The sulfide is then oxidized to elemental ...
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Mar 01, 2014 Sulfur reduction. This graph shows SO 2 ... From Flue Gas to Gypsum. The sulfur-scrubbing process at a coal-fired power plant typically involves grinding high …
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In this study, the changes in the chemical form of calcium on reduction with solid carbon were investigated in order to develop a process for the regeneration of CaO from spent gypsum at low temperatures. Calcium sulfate dihydrate was used as a model compound for gypsum; it was mixed with solid carbon and heated to a terminal temperature of 1100 C.
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Large native (i.e., elemental) sulfur deposits can be part of caprock assemblages found on top of or in lateral position to salt diapirs and as stratabound mineralization in gypsum and anhydrite lithologies. Native sulfur is formed when hydrocarbons come in contact with sulfate minerals in presence of liquid water. The prevailing model for native sulfur formation in such settings is that ...
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Mar 06, 2018 The costs calculated for the biological sulphate reduction process were significantly higher than the costs of gypsum precipitation and RO. The SRB process would show significant advantages if elemental sulphur could be produced as an end sulphur product, which …
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A combined chemical and biological process for the recycling of flue gas desulfurization (FGD) gypsum into calcium carbonate and elemental sulfur is demonstrated. In this process, a mixed culture of sulfate-reducing bacteria (SRB) utilizes inexpensive carbon sources, such as sewage digest or synthesis gas, to reduce FGD gypsum to hydrogen sulfide.
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Sulfate ores like gypsum treated with carbon to produce metal sulfide. The metal sulfide reacts with the acid to form hydrogen sulfide which converts sulfur by the self-reduction process. Natural gas refinery. Recently, a large scale of sulfur extracted by natural gas refinery process which contains 15 to 20 percent of hydrogen sulfide.
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The process involves the crushing, separation and sieving the gypsum plaster from the paper. The recovered Gypsum can then be re-used in the cement and gypsum industry helping reduce raw material use in new products or in agriculture as a source of Sulphur and …
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The first is the reduction of pyrrhotite with carbon in the presence of lime to produce iron, calcium sulfide, and carbon monoxide, followed by reaction of calcium sulfide with gypsum to produce lime and a concentrated sulfur dioxide stream. The kinetics of the reactions involved in the two-stage process is studied using thermogravimetric analysis.
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Process Background Hydrogen sulfide gas (H 2S) occurs in nature and as a product of many in-dustrial processes. It can be formed from sulfur compounds, including sul-fates, or from sulfur itself. As a frequent by-product of indus-trial processes, it is generated by the reaction of sulfur compounds with organic materials (reducing agents)
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This process is a true reduction of total dissolved solids (TDS) in that all chemicals added for treatment are precipitated during the reactions. Operating costs for near-complete sulfate removal using the process, which has been demonstrated successfully for many industrial …
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Dec 01, 2015 At completion of the reduction process, CaS r was stored in a nitrogen environment to avoid spontaneous oxidation to CaSO 4 (Garc a-Calzada et al., 2000). The procedures used for the thermal reduction of gypsum waste and the characterisation (i.e. XRD and XRF) of gypsum waste and formed CaS r were described elsewhere (de Beer et al., 2014).
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Sulfur in coal exists in inorganic and organic forms, the former being mostly pyritic sulfur. Total sulfur contents in major coalfields are in the range of roughly 0.5–10 wt%. In coal combustion, to generate electric power and process heat, the sulfur is emitted as SO2, which is seen as one of the main causes of acid rain. This effect has led ...
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The basic steps of the sulphur recovery process from gypsum are: • Reduction of gypsum to calcium sulphide using reducing agents (Matsuya and Yamane, 1981), for example, coal or activated carbon (Eq. (1)), CaSO. 4(s) + 2C(s) CaS(s) + 2CO2(g) (1) • Suspending the calcium sulphide obtained from Eq. (1) in water to form a CaS slurry.
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The processes involve the reductive roasting of gypsum using coal, natural gas, carbon monoxide, or hydrogen to produce sulfur dioxide, which is converted to sulfuric acid. The U.S. Bureau of Mines has investigated the reductive roasting of gypsum (3), the conversion of calcium sulfide (CaS) to elemental sulfur (4), and sulfur dioxide emission
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Aug 22, 2014 The process evaluated consists of the following stages: reduction of gypsum to calcium sulphide; stripping of the sulphide with CO2 gas and the production of sulphur. …
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A method for decomposition of phospho-gypsum or natural gypsum, characterised in that it comprises mixing the said gypsum with natural sulphides in any suitable ratio and burning the resulting...
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Feb 21, 2017 The advantage of the gypsum is that it reduces the amount of water soluble P that can be lost through runoff or leaching without causing any permanent reduction in P available to plants. If soil test P levels are extremely low, then the addition of gypsum could potentially further reduce the …
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Preferably, the aqueous discharge from the scrubber is divided, with a major portion passed to a separator to remove gypsum, therefrom, while a minor portion is passed to the regeneration tank....
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