Furnace method

These are called high temperature induction furnace methods which differ only as to the kind of furnace used and employ the same ASTM procedure. The sample is heated to over 1300°C in an oxygen stream and transformed to SO2 which is analyzed with an infra-red detector. 

Phosphoric Acid. The only inorganic acid used for food appkeations is phosphoric acid [7664-38-2] H PO, which is second only to citric acid in popularity. The primary use of phosphoric acid is in carbonated beverages, especially root beer and cola. It is also used for its leavening, emulsification, nutritive enhancement, water binding, and antimicrobial properties. Eood-grade phosphoric acid is produced by the furnace method. Elemental phosphoms is burned to yield phosphoms pentoxide which is then reacted with water to produce phosphoric acid (see Phosphoric acid and the phosphates) (12). 

The most common method of converting iron ore to metallic iron utilizes a blast furnace wherein the material is melted to form hot metal (pig iron). Approximately 96% of the world s iron is produced this way (see Iron). However, in the blast furnace process energy costs are relatively high, pollution problems of associated equipment are quite severe, and capital investment requirements are often prohibitively expensive. In comparison to the blast furnace method, direct reduction permits a wider choice of fuels, is environmentally clean, and requires a much lower capital investment. 

R. B. Burt and J. C. Barber, Production of Elemental Phosphorus hy the Electric-Furnace Method Chemical Engineering Report No. 3, Tennessee VaUey Authority, Wilson Dam, Ala., 1952. 

Calcium carbide was first made ia the laboratory ia the mid-1800s. Commercial production by the electric furnace method was developed about 1892 by Moissan ia France and iadependendy by Willson ia the United States. Development of the carbide iadustry for generation of acetylene began ia 1895 and expanded rapidly. 

These refer to the control of a chemical process and include planning for familiar tasks (e.g., change type of fuel-firing in a furnace) or planning for familiar but infrequent tasks (e.g., start-up or shutdown a furnace). Methods of task analysis and error analysis can be used to analyze well-established strategies that operators use to perform procedural tasks and identify the user s information needs. An implication for display design would be that all information needed... 

In similar work, Sturgeon et al. [125] compared direct furnace methods with extraction methods for cadmium in coastal seawater samples. They could measure cadmium down to 0.1 pg/1. They used 10 pg/1 ascorbic acid as a matrix modifier. Various organic matrix modifiers were studied by Guevremont [116] for this analysis. He found citric acid to be somewhat preferable to EDTA, aspartic acid, lactic acid, and histidine. The method of standard additions was required. The standard deviation was better than 0.01 pg/1 in a seawater sample containing 0.07 pg/1. Generally, he charred at 300 °C and atomised at 1500 °C. This method required compromise between char and atomisation temperatures, sensitivity, heating rates, and so on, but the analytical results seemed precise and accurate. Nitrate added as sodium nitrate delayed the cadmium peak and suppressed the cadmium signal. 

Halliday et al. [396] have described a simple rapid graphite furnace method for the determination of lead in amounts down to 1 xg/l in polluted seawater. The filtered seawater is diluted with an equal volume of deionised water, ammonium nitrate added as a matrix modifier, and aliquots of the solution injected into a tantalum-coated graphite tube in an HGA-2200 furnace atomiser. The method eliminates the interference normally attributable to the ions commonly present in seawater. The results obtained on samples from the Firth of Forth (Scotland, UK) were in good agreement with values determined by anodic stripping voltammetry. 

Give a brief description of the graphite furnace method of atomization. 

The graphite furnace method of atomization utilizes a small graphite tube furnace to electrically heat rapidly a small volume of the analyte solution contained inside to a temperature that eventually causes atomization. 

Bohm (Ref 4) claimed that he invented a similar process earlier than Willson and applied for patent in 189L hut the patent was not issued until 1895- The electric arc furnace method invented in 1892 is essentially the same as the current method of manuf of CaCj. Detailed description of the method is given in Refs 5,6,7 8. The coml prod contains CaO,graphite and some other impurities... 

Bergman in that year announced, apparently on the basis of Scheele s work, that the black magnesia was the calx of a metal as difficult to fuse as platina. Gahn, the Swedish mineralogist, however, in the same year succeeded in obtaining manganese metal by improved furnace methods. 

The Determination of Selenium. The most difficult trace element to determine in coal by wet chemical methods is selenium. Two alternative dissolution techniques can be used—H. L. Rooks combustion method (7) and the oxygen bomb combustion method (4). Also, two alternative analytical methods can be used—the hydride evolution method (5) and the graphite furnace method. 

The graphite furnace method can also be used as described in the bomb combustion procedure. Table V compares graphite furnace values with conventional flame AAS or NBS neutron activation analyses. 

Figure 2. Relationship of flame spread to level of chemical retention in 3/8-in. Douglas fir plywood evaluated by the 8-ft tunnel furnace method...

The work of laboratories of moderate resources is based upon resistance furnace methods. More elaborate methods, such as high-frequency induction, cooled-crucible arc, electron bombardment, or mirror furnaces, with their resulting higher temperature ranges are financially beyond the reach of these laboratories. 

Consequently, rather than simulating a specific fire scenario, conditions in smoke chamber tests vary over time and are not well-defined. A relatively new tube furnace method greatly alleviates this problem and, for that reason, is gaining increased international acceptance. The method is described in ISO TS 19700. 

P. Blomqvist, T. Hertzberg, H. Tuovinen, K. Arrhenius, and L. Rosell, Detailed determination of smoke gas contents using a small-scale controlled equivalence ratio tube furnace method, Fire and Materials, 31(8), 495-521, 2007. 

NFX 70-100 Analysis of pyrolysis and combustion gases. Tube furnace method. Part 1, Methods of analysis of gas generated by thermal degradation. Part 2, Method of thermal degradation using tube furnace. 

BS 7990 Tube furnace method for the determination of toxic products yields in for effluents. 

Alkaline Earth Phosphides.—An impure calcium phosphide, made by exposing lime at a red heat to the vapour of phosphorus, was used in the preparation of phosphine.2 Calcium phosphide probably is also formed during the manufacture of phosphorus by the electric furnace method g.v.). It has been prepared by heating calcium phosphate and lamp black in the electric arc furnace, and appeared as a crystalline reddish-black substance.3 Calcium phosphide prepared in this manner is only acted upon slowly by water at the ordinary temperature, but readily by aqueous solutions of strong acids. Concentrated nitric and sulphuric acids, and oxygen and chlorine, do not attack it at ordinary temperatures, but on heating it is oxidised, e.g. by chlorine above 100° C. and by oxygen above 300° C. 

Furnace Methods.—Phosphoric acid can be prepared from the pentoxide, which is sublimed at high temperatures from a mixture of calcium phosphate, sand and coke. Phosphorus is first produced and then burns to the pentoxide. Reduction proceeds according to the... 

Lead Determine as directed for Method I in the Atomic Absorption Spectrophotometric Graphite Furnace Method under Lead Limit Test, Appendix IIIB. 

Lead Determine as directed for Method I in the Atomic Absorption Spectrophotometric Graphite Furnace Method under Lead Limit Test, Appendix IIIB, using a 10-g sample. Oxalate Neutralize 10 mL of a 1 10 aqueous solution with 6 N ammonium hydroxide, add 5 drops of 2.7 N hydrochloric acid, cool, and add 2 mL of calcium chloride TS. No turbidity develops. 

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