Carbonation/calcination process

T. J. Carbone, "Production Processes, Properties, and Apphcations for Calcined in High-Purity Aluminas," in L. D. Hart, ed., Jilumina Chemicals Science and Technology Handbook, The American Ceramic Society, Columbus, Ohio, 1990. 

Recently, the influence of the preparation method of various MgO samples on their catalytic activity in the MPV reaction of cyclohexanone with 2-propanol has been reported 202). The oxides were prepared by various synthetic procedures including calcination of commercially available magnesium hydroxide and magnesium carbonate calcination of magnesium hydroxides obtained from magnesium nitrate and magnesium sulfate sol-gel synthesis and precipitation by decomposition of urea. It was concluded that the efficiency of the catalytic hydrogen transfer process was directly related to the number of basic sites in the solid. Thus, the MgO (MgO-2 sample in Table IV) prepared by hydration and subsequent calcination of a MgO sample that had been obtained from commercially available Mg(OH)2 was the most basic and the most active for the MPV process, and the MgO samples with similar populations of basic sites exhibited similar activities (Table IV). 

Coke which is low in sulfur and metal content is valued as a fuel, as a raw material for the manufacture of electrodes, and in graphite production. To produce high-purity coke, all traces of volatile matter must be removed from coke. A calcination process is utilized for this purpose. This process requires the coke to be heated to temperatures of 2,000°F (1,093.3°C) or higher. The pure coke is valued as raw material for the manufacture of electrolytic cell anodes and as a pure carbon source. 

At this time Lavoisier did not know whether the air of the atmosphere or some part of it was the material fixed in the calcination process. Perhaps because he was entirely ignorant on this matter, he identified it as fixed air (carbon dioxide) of Joseph Black, the only specific example then known of a specific air that could be fixed. It was of course already well known that fixed air was produced from the reduction of metallic calx. 

Petroleum coke calcining is a process whereby green or raw petroleum coke is thermally upgraded to remove associated moisture and volatile combustible matter (VCM) and to otherwise improve critical physical properties, e.g., electrical conductivity and real density (JL ) The calcining process is essentially a time-temperature function the most important variables to control are heating rate, VCM to air ratio and final temperature. To attain the calcined coke properties necessary for its end use by the amorphous carbon or graphite industries, the coke must be heat treated to temperatures of 1200-1350°C (2200-2500°F), or higher, to refine its crystalline structure. 

Cadmium pigments have been manufactured by both a direct calcination process and a precipitation-calcination process. In the first instance, a mixture of cadmium carbonate and sulfur (and zinc oxide and selenium if the hue to be produced requires their addition) is calcined at 520-600°C for 1-2 h. This direct calcination process is complicated by the volatility of cadmium oxide and selenium, both of which are toxic and require special handling. In the precipitation process, an alkali sulfide solution is added to a solution of cadmium and (in the case of green-shade yellows) zinc salts or to a solution of cadmium and (in the case of deep oranges, reds, and maroon) selenium metal to precipitate the appropriate compound. The precipitate is washed, dried, and calcined at 600-700°C in an inert or reducing atmosphere to convert the precipitated cubic structure to a more stable wurtzite crystal. The calcination conditions control particle size, which ranges from 0.2 to 1.0pm. 

On the other hand, hydrogen membranes and the reaction-based processes using solid sorbents can separate CO2 while operating at the elevated temperatures of the gasifier. Such methods utilize the carbonation/ calcination cycle of a solid metal oxide (MO). ... 

The extract contains, in addition to the sucrose, further solved or colloidally dispersed components, which in the juice purification stage must be - as far as possible - precipitated or destroyed under alkaline conditions by adding calcium oxide. This is carried out by a multi-stage, continuous treatment with, first, calcium oxide and, second, carbon dioxide. Both processing aids are produced in a separate calcining process in parallel. The excess calcium oxide is precipitated in so-called carbonation vessels with carbon dioxide from the calcining process. All precipitates and deposits are separated in a multi-step filtration. The sludge... 

Calcination transforms basic carbonates into oxides by endothermic processes. (Cu,Zn)-hydroxycarbonates are identified as especially adequate precursor phases, which transform into a mixture of oxides. To gain more insight into the transformations, which depend mainly on composition (phases), but also on crystallite size and the chosen conditions, the calcination process can be... 

Another production method used for the conversion of the UF-a to UO2 is the ammonium uranyl carbonate (AUC) process. The form of the AUC precipitate is probably (NHa) [UOz(COa)3]s. This compound is calcined to UOior UjOa, which is then reduced to UOa. 

Wang W, Ramkurmar S, Li S, Wong D, Iyer M, Sakadjian BB, et al. SubpHot demonstration of the carbonation-calcination reaction (CCR) process high-temperature CO2 and sulfur capture from coal-fired power plants. Ind Eng Chem Res 2010 49 5094-101. 

The Ohio State University proposed a method to combine coal gasification with a carbonation/calcination reaction (CCR) process to produce hydrogen [27]. CCR is also a sorption-enhanced process. In contrast to the ZECA process, the CCR method uses CaO to promote WGS reaction as follows ... 

For dolomite, the calcination process involves the thermal decomposition to calcium carbonate and magnesium carbonate, followed by two half calcination steps, the first forming magnesia (MgO) and the second CaO ... 

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