발간논문

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There has been no fixed opinion on the behavior of phosphate in chlorination of monazite. To obtain fundamental information on the behavior of phosphate in chlorination of monazite, thermodynamic considerations on chlorination of calcium phosphate were made, and phosphoric chlorides obtained by chlorination of the phosphate under various conditions were examined using a mass spectrometer. The results showed that phosphorous oxychloride was formed at 500˚, 600˚and 700℃, and both phosphorous oxychloride and phosphorous trichloride were formed at 800˚and 900℃. It is concluded from the results mentioned above that, in chlorination of monazite, phosphorous oxychloride is formed at low temperatures, and both phosphorous oxychloride and phosphorous trichloride are formed at high temperatures.

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Based on the results described in Part 1, 2 and 3, the optimum condition for recovering thorium and so-called rare earths from Korean monazite was determined, using a horizontal tube electric furnace. When the monazite was decomposed with chlorine at 700℃ using the -200 mesh monazite and charcoal respectively, the weight ratio of charcoal to monazite 0.2, the size of briquette 6-10 mesh, and a chlorine flow race 430cc/min, thorium and so-called rare earths were obtained with high recovery. And it was observed that chlorides of thorium and Yttrium may be selectively volatilized, when the monazite was decomposed at about 900℃. With the mixed oxides of thorium and so-called rare earths obtained by wet process from the chlorides prepared by chlorination of the monazite at 700℃, selective separation of the values was examined by chlorination method. The results showed that lanthanum, cerium and thorium were selectively separated to an extent by the chlorination at about 200℃.

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Decomposition of gaseous thorium tetrachloride with oxygen was examined. It was observed that ultra fine particle of thorium oxide was obtained by this method.

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The new trend of metallurgical education and current curriculum in under-graduate courses was analyzed in comparition with over fifteen domestic and international typical schools. The correlation of metallurgical engineering education and industrial request was referred in addition to the analysis of educational curriculum constituents. Chemical Metallurgy, Physical Metallurgy, and Process Engineering Metallurgy are main constituents of metallurgical curriculum based on Chemistry, Physics, and Engineering. The basic and applied science was currently emphasized rather than process engineering metallurgy, Humanities and Social Science courses were currently increased in numerous schools.

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It is widely believed that application of tonnage oxygen in steel making process results in increased production capacity, decreased fuel consumption, and superior steel quality. Based on the practical operation data of the utilization of oxygen in an open-hearth furnace, this paper summarizes some effective results and problems on the particularities of the process. At the oxygen consumption of 25∼30㎥ per ton steel, about 25 percent of refining time was shortened and 35 per cent of increased steel production per hour could be expected. Inevitable corrosion of the furnace lining could remarkably be decreased with the change of main roof and using cooling jacket in the front and back wall. Annual steel production has been increased about 23 percent and also production cost decreased.

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