Molten metal pyrolysis

Molten metal pyrolysis 2007 to 2008 Molten Metal Technologies. Cambridge. Mass. Elkem Technology. Oslo. Norway... 

Molten metal pyrolysis Involves use of metals, such as copper, iron, or cobalt, at 3,000 degrees Fahrenheit, to decompose organic compounds like chemical agent. 

A form of pyrolysis utilized industrially concerns PMMA (Figure 2.5). PMMA waste, which is generally clean and which does not leave the industrial circuits, is collected and thrown into a bath of molten metal. PMMA decomposes itself by restoring 97.2% of monomers, which can be used for the polymerization of new plates of PMMA. The method works less well if the waste is too dirty. 

The basic approach to classify powder production methods is based on whether a method is top-down or bottom-up. In a top-down method, micro- and nano-particles are produced due to the stracture and size refinement through the breakdown of the larger particles in a bottom-up method, the mechanism of particle formation is usually by means of nucleatimi, growth and aggregation of atoms and molecules. In a more practical approach, one may divide the powder synthesis methods as follows (1) wet chemistry, such as the chemical precipitation, sol-gel, microemulsion, sonochemistry, and hydrothermal synthesis methods (2) mechanical attrition, grinding and milling (3) gas phase methods, such as the chemical and physical vapor deposition (4) liquid phase spray methods, such as the molten metal spray atomization, spray pyrolysis, and spray drying, and (5) liquid/gas phase methods. 

On the basis of laboratory work of Morell and co-workers, a pilot plant was set up for further study of the pyrolysis step. Results are reported by Schniepp, Dunning, Geller, Morell, and Lathrop (115). The equipment consisted essentially of a metal pyrolysis coil in a bath of molten lead for the main step of the process. Vapors from the coil were cooled rapidly in a quench chamber and passed through a packed column where acetic acid and other liquid pyrolysis products were washed out. The butadiene gas was scrubbed, dried, compressed, and finally condensed to liquid for collection and weighing. It is interesting at this point to note the pilot plant recoveries tabulated by Schniepp and co-workers. These are given below as over-all recoveries of butadiene from the glycol. 

Beside continuous horizontal kilns, numerous other methods for dry pyrolysis of urea have been described, eg, use of stirred batch or continuous reactors, ribbon mixers, ball mills, etc (109), heated metal surfaces such as moving belts, screws, rotating dmms, etc (110), molten tin or its alloys (111), dielectric heating (112), and fluidized beds (with performed urea cyanurate) (113). AH of these modifications yield impure CA. 

In pyrolysis employing molten tin, a flow of the urea on the surface is eventually converted to a sheet of cmde CA 15—20 mm thick. After reaching the edge of the tin bath, the moving sheet falls into a mill. The resultant powdered cmde CA (contaminated with tin metal) is subjected to acid hydrolysis to convert aminotriazines (30—40%) to CA. Tin losses can amount to 15 kg/1 product. 

Owing to the slow rates of diffusion of the cations, the direct solid-state reaction of the oxides Cr2 03 and MO at an elevated temperature is not a good preparation of divalent metal chromium(III) oxides. They can be prepared by more elaborate methods, such as controlled reduction of dichromates MCr207,1 reaction of dichromium tungsten oxide Cr2W06 with a molten divalent metal fluoride2 at 1400°, pyrolysis of complexes,3 and pulverization of slurries containing Cr2 03 and a divalent metal salt.4... 

A new version of MCFC technology - the direct carbon fuel cell (DCFC) - is under development at the Lawrence Livermore National Laboratory in the USA. Instead of using gaseous fuel, a slurry of finely divided carbon particles dispersed in molten alkali metal carbonates is fed to the cell. The carbon is made by the pyrolysis of almost any waste hydrocarbon e.g., petroleum coke), a process that is already carried out industrially on a large scale to produce carbon black for use in the manufacture of tyres, inks, plastic fillers, etc. The pyrolysis reaction yields hydrogen that can itself be utilized in another fuel cell ... 

After mining, the raw ore is finely crushed and ground and undergoes a froth flotation ben-eficiation process to concentrate and separate celestine from byproduct minerals (e.g., barite). Then, the concentrate ore is reduced by pyrolysis in a kiln to strontium sulfide (i.e., SrS or black ash). The black ash is then dissolved in pure water, and the aqueous solution is treated with sodium carbonate to precipitate the strontium-carbonate crystals. After the strontianite crystals are removed and dried, the strontianite undergoes a calcination, evolving carbon dioxide and giving anhydrous strontium oxide (i.e., SrO, strontia). Strontium metal can be obtained either by thermal reduction of this strontium oxide with molten aluminum in a vacuum or by fused strontium chloride electrolysis. 

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