발간논문

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The characteristics of the roasting of the concentrates and tailings which were produced from molybdenite flotation with bismuthinite semi-concentrate, were studied. This bismuthinite semi-concentrate (Bi 20.5%, MoS₂13%) has been produced as a by-product scheelite flotation at the Sang-Dong Mine, K.T.M.C. It was found that the multiple hearth furnace is useful to roast more than 15 per cent of molybdenite and fluo-solid roaster less than 15 per cent. The results which were obtained through the fluo-solid roasting are as following. 1) Sulphure was contained more than 3 per cent in the ore which was roasted below 600 degrees (℃). 2) De-sulphurization rate was about 55 per cent.

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This paper, covering the hydrometallurgical process for the treatment of marmatite concentrates, describes the bench-scale experimental program undertaken as a basis for further pilot plant development. Zinc ferrite formations during the roasting were analyzed by the X-ray powder method. The solubilities of roasted calcines in dil. sulfuric acid, solution purification and zinc electrolysis, and a few relating problems were reviewed. Optimum conditions for the processing of domestic marmatite ores were pointed out.

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The silica sand of Hucksan, Chaun and Bigum islands were tested by chemical and sieve analysis. And also their green compressive strength and permeability having different combination of clay and water with one per cent of real were studied. The results of the experiment are summarized as follows: 1. The purity and grain distribution of all sand are good, but they are not suitable for a molding sand of large steel castings because of their fineness of grain size. 2. As shown in the tables 3, 4 and 5, green compressive strength of their clay-silica sand is best at 4 per cent of temper water. 3. As the clay content increases, green permeability decreases, but at the same clay content the permeability increases with temper water. 4. The purity, refractoriness, fineness and distribution of Hucksan and Chaun islands sands are suitable for the molding sand of the shell molding process and the CO₂process.

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The surface diffusion coefficients (D_s) for Au^(198) on (100) and (111) surfaces of copper have been determined between 1050˚and 780℃ using a new analysis and experimental procedure. The results are ; (111) : D_s (Au)=2.1×10^5 exp (-51,100/RT) sq cm per sec. (100) : D_s (Au)=3.6×10^5 exp (-52,000/RT) sq cm per sec. D_s has also been determined for Cu^(64) at 870℃ and the values found are 4.5 times larger than these by the grain boundary grooving technique for the same surface orientations. This difference is felt to result from the approximate nature of the mathematical solution used in the present work. Attempts to measure D_s for silver on copper and silver surface indicated a means of matter transport different from surface diffusion was dominant in missing tracer from the source out over the surface. Calculations and experiment both indicate that this is the flow of silver through the vapor phase which completely masks the much smaller flow due to surface diffusion. The previous self-diffusion studies of D_s for silver and copper are discussed in terms of our own analysis and found to yield values of D_s factors of 10^5 or more greater than found by the grain boundary grooving technique.

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