Training of the models and the assessment of their quality are performed using the historical data collected in the hydrate crystallization area at the operating alumina refinery. View Show abstract
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Processes 2021, 9, 390 3 of 15 2.2. Thermal Infrared Spectroscopy Analysis The test parameters of the thermal analyzer (NETZSCH 409PC STA, Selbu, Germany) and infrared spectrometer (Bruker FTIR-7600, Karlsruhe, Germany) were 90% N2 + 10% O2 atmosphere; a flow rate of 75 mL/min; heating rates of 5, 10, 15, and 20 C/min; and a sample mass of 5.0 0.5 mg.
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During operational upsets, high transient pressures through a tube digestion unit can potentially expose plant, equipment, and personnel to operational safety risks. Solutions The use of innovative high-capacity, single-stream tube digestion technology reduces refinery complexity and improves energy efficiency.
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: Ma¶aden, laboratory, quality, Metrohm, alumina. 1. Introduction. It is the quality and production cost of the final product that will determines the success of any alumina refinery. The target is a high-quality alumina product made at a cost lower than its competitors. For this reason, the alumina laboratory provides an important service and ...
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Aluminium (Al) is the third most common element in the Earth's crust and occurs naturally in drinking water and agricultural products, and humans are consequently exposed to the element from ...
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Alumina Quality . Aluminium smelters negotiate contractual specifications with refineries for alumina since it a major raw material impacting electrolysis process efficiencies and quality of the molten metal delivered to the casthouse. The effects of alumina quality on the . smelter are well understood [10] and some of the key issues are:
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Table I. Theoretical maximum yield and process conditions Digestion Precipitation Yield 675 160 g/l A/C feed 0.190 0.800 A/C discharge 0.800 0.190 C feed flow 1110 265 g/l T > 150 30 C DIGESTION Alumina dissolution in digestion is, from a thermodynamic point of view, primarily controlled by the following parameters: The alumina mineral phase ...
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The operating parameters affecting the digestion of bauxite in Iran Alumina Plant is shown in Table 4. In this research work, the four factors residence time, temperature, Na2O concentrationt and lime content in three levels were used to investigate their relationship with the digestion efficiency, A/S, and N/S using RSM in the
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Required quality of the final output alumina is based on the application (viz., for metallurgical purpose or production of fine chemicals) and hence decides the price. For example, smelter grade alumina produced in Australia must meet the typical quality parameters listed in Table 1 (Methodology and Specifications Guide, Alumina, 2011).
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The α phase content of alumina is an important quality parameter for use of alumina in ceramics, catalysts and other industries/applications. ... -Al 2 O 3 reference material for determination by powder diffraction method has been developed under the optimum production equipment and technological parameters, ... the cell parameters of alumina ...
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Bauxite residue is an insoluble solid waste by-product generated after the digestion of gibbsitic bauxite ore with sodium hydroxide at elevated temperature and pressure in the Bayer process for the extraction of alumina. During the digestion process, aluminum minerals react with caustic soda process liquor to form soluble sodium aluminate ...
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The alumina digestion process (ALDP) is a key component of the Bayer alumina refinery, where recycled alkali solution reacts with aluminum hydroxides in bauxite slurry under high …
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stream low temperature digestion facility to a single stream operation. A review of process performance parameters and design considerations will be discussed. Keywords: low temperature digestion; dual stream, single stream. 1. Introduction. Alumina refineries use primarily the "Bayer" process to extract alumina from Gibbsitic,
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four main stages in the Bayer Process: digestion, clarification, precipitation and digestion [1]. Calcination is the last stage of Bayer Process, where the aluminium trihydroxide (Al(OH) 3), formed and separated in the preceding process stages, has its hydroxides removed, forming the aluminum oxide (Al 2 O 3) and water.
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The Specific Surface Area (SSA) reduced from 128 m 2 /g at 900 °C to 69 m 2 /g when the wall temperature was increased to 1120 °C. A similar trend in LOI was observed in the moisture-bound aluminum hydroxide raw material. The SSA decreased from 185 m 2 /g at 750 °C to 84 m 2 /g at 1050 °C. Alumina conversion to SGA quality standards (at least 99%) was …
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This paper presents a soft sensor model for a high-pressure digestion process to control the raw material proportioning for the bauxite slurry blending process in the alumina metallurgical industry.
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Alumina (Al 2 O 3) is an intermediate raw material generated during the production of aluminum from bauxite ore.Processing parameters such as particle size, Al2O3 polymorphs, or impurities have a direct impact on the use of energy and chemicals during refining and smelting and therefore affect both the efficiency and profitability of the process.
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The operation variables, including feed rate of ore slurry, caustic solution and live steams in the double-stream alumina digestion process, determine the product quality, process costs and the environment pollution. Previously, they were set by the technical workers according to the offline analysis results and an empirical formula, which leads to unstable process indices …
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Processes 2021, 9, 390 2 of 15 process is extremely difficult [13–16]. Roasting desulfurization is considered an ideal desulfurization method, as the pyrite in high-sulfur bauxite can be ...
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Four parameters were assessed for the digestion: (1) test portion size, (2) maximum digestion temperature, (3) digestion reagents and (4) digestion duration. These param-eters were decided based on the answers provided by PT participants (Table S1) in order to be representative of the practices in the participating NRLs. The detailed assess-
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In the Bayer process, used for the production of alumina from the bauxite ores, there are frequent disturbances and a large number of interacting processes which incorporate considerable dead time.
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The desulfurization ratio, Al2O3 digestion ratio, and dynamics of alumina digestion were investigated. Moreover, the mechanism of the effect of roasting on alumina digestion was studied by DFT simulations. 2 Experimental 2.1 Materials A LGHS bauxite sample was obtained from Guizhou Province, China, and its composition is given in Table 1.
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Therefore the quality of natural water sources used for different purposes should be established in terms of the specific water-quality parameters that most affect the possible use of water.
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Most of the silicon fractions were separated by the solution, enriching the red mud iron grade to 50%. The alumina digestion rate of bauxite could reach 85% by this method. ... the equipment requirements have a high cost because the Na 2 O concentration used in this method is very high. Most of the silicon oxide also enters the solution during ...
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Alumina refineries use primarily the "Bayer" process to extract alumina from Gibbsitic, Boehmitic or Diasporic bauxites. Refineries processing Gibbsitic bauxites require a low temperature …
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Currently working as Shift Manager for the entire refinery comprising four different operation centers (Digestion. Clarification, Hydrate & Precipitation, Calcination) at Al Taweelah Alumina Refinery with 13+ years of experience in operations & production, Commissioning, De-bottlenecking, Major tank turnarounds, process optimization in Alumina refinery.
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Alumina extraction from residue in the 2 nd digestion step does not require bauxite mining, crushing, transport, grinding, slurry holding, liquor decantation, residue washing and evaporation.
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With depleting gibbsitic or tri-hydrate bauxite reserves and the recent step increase in energy costs, alumina plant operators are looking for ways to process boehmitic or mono-hydrate …
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(SRMs) 699 Alumina (Reduction Grade). Alumina is considered to be one of the most refractory ceramic materials. Several publications have been devoted to the digestion of this material2–7 for trace element analysis by inductively coupled plasma optical emission spectrometry (ICP-OES). Alkali fusion, open beaker digestion with a
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to form aluminium metal. Two parameters which are often used to assess the viability of a bauxite deposit are described as "Available Alumina" and "Reactive Silica". Available Alumina defines the net amount of Al 2O 3 that can be extracted from the bauxite using conditions that simulate the extraction of alumina in the Bayer process.
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