발간논문

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Roasting mechanism of synthetic chalcocite (Cu_(1.96)S) was studied by means of D. T. A, under the conditions of the flow rate of air, 150cc/min, and the rate of temperature increment, 3℃/min. The reaction mechanisms of the exathermic and endothermic reactions in the range from 330℃ to 780℃ may be given as the followings: ① at 330℃: Exo. reaction(1st peak) 5Cu_(1.96)S+1/5O₂→Cu_9S_5+2/5Cu₂O ② at 390℃: Exo. reaction(2nd peak) Cu₂S+3/2O₂→Cu₃O+SO₂ ③ at 470℃: Endo. reaction(3rd peak) 3Cu₂S+6CuSO₄→6Cu₂O+9SO₂ ④ at 490℃: Exo. reaction(4th peak) Cu_9S_5+29/4O₂→9/2Cu₂O+5SO₂ ⑤ at 650℃: Exo. reaction(5th peak) Cu₂O+SO₂+O₂→CuO, CuSO₄ ⑥ at 750℃: Endo. reaction(6th peak) CuSO₄→Cuo, CuSO₄+SO₃ ⑦ at 780℃: Endo. reaction(7th peak) CuO, CuSO₄→2CuO+SO₃

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The effect of Fe-ion was studied on the consumption of electric power and current efficiency per ton of deposited zinc in the zinc electrolysis. The composition of electrolyte was 65g/ℓ Zn and 140g/ℓ free H₂SO₄ and the temperature of electrolyte was 35℃. In the presence of 1㎎/ℓ Fe current efficiency was lowered by about 1% and 0.5% at current densities of 370A/㎡ and 650A/㎡ respectively and the consumption of electric power was increased by about 17KWh/t Zn and 12KWh/t Zn respectively.

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The diffusivity of hydrogen in pure liquid copper was determined by an unsteady-state gas liquid metal diffusion cell technique. The diffusion cell was formed by immersing an alumina tube containing hydrogen gas at 1 atm. in a bath of stagnant liquid copper. Diffusivities were calculated from the appropriate solution of Fick`s 2nd law. The effect of silicon, an alloying element, on the diffusion of hydrogen was also investigated. The absorption of hydrogen in stagnant pure liquid copper has been found to be diffusion controlled. The calculated diffusivities, D_H for hydrogen in pure liquid copper can be described by the equation: D_H=5.028×10^(-2)=exp(-2,628±1,290/RT)㎠/sec in the temperature range of 1,090℃-1,205℃.

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The average velocities of 60°-dislocations in silicon single crystals have been measured be Stein and Low method. The stress dependence of dislocation velocities is described as v∝τ^m at a given temperature over the stress range of 0.5∼5 ㎏/㎟. It was observed that stress exponent m depended on temperature. The temperature dependence of dislocation velocities is described as v∝exp (-E/kT) with activation energy of 1.5 electron volt at the resolved shear stress of 2 ㎏/㎟.

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Ferric sulfate and sodium sulfate in the aqueous solution were reacted to form Jarosite at elevated temperature. The formation of Jarosite (Natro-jarosite and Hydronium-jarosite) was favored at initial pH value below 1.7 and ferric hydroxide formed at initial pH value above 1.8. The formation of ferric hydroxide was appeared to be colloidal, which is to be avoided. The pH value of the solution must be controlled below 1.7 for the formation of crystallized precipitation, i. e. Jarosite compounds. The optimum condition of Jarosite formation was obtained at 110℃ in the pH value of 1.7. The ratio of Natro-jarosite to Hydronium--jarosite was increased with increasing temperature.

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The particle size influence on the activated sintering was investigated. The finer partilces accelerate the densification of the Ni-doped W compact, especially in the initial stage of sintering. The relation between the average particle size and sintering time, was obtained experimentally and discussed. The pore coalescence phenomena could be also observed during sintering.

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In order to recover zinc and obtain a suitable raw material for iron smelting from the copper converter slag, chloridizing volatilizition experiment has been performed using calcium chloride (CaCl₂·2H₂O) and ferric chloride (FeCl₃·6H₂O) as chloridizing agents, and calcium nitrate [Ca(NO₃)₂·4H₂O] and calcium carbonate (CaCO₃) as additives. The effects of the temperatures and times of drying and roasting, and the amounts of chloridizing agents as well as the additives on the removal of zinc from the slag have been tested and discussed experimentally and thermodynamically. By the way, the result on the copper was also added for the purpose of the comparison. The results summarized are as follows; (1) The optimum roasting temperature was found to be 1100℃, an hour of roasting time was good enough for the purpose, and the optimum amounts of calcium chloride (CaCl₂·2H₂O) was 23.37pct. (2) Ferric chloride (FeCl₃·6H₂O) as a chloridizing agent was found to be not effective, the addition of calcium nitrate [Ca(NO₃)₂·4H₂O] together with calcium chloride to the slag was shown the best result, and the addition of calcium carbonate (CaCO₃) to calcium chloride was more effective than calcium chloride only. (3) The slag roasted at 1200℃ was considerably harder than that of 1100℃, and copper was more readily removed from the slag than zinc. Under the optimum conditions, 1.77 pct of zinc in the slag was reduced to 0.03 pct, while 5.43 pct of copper to 0.01 pct.

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