<寄書>鉛熔鑛爐〓中の鉛に及ぼすCO_2 : CO比の影響
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概要
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Generally speaking, the loss of lead in its blast-furnace smelting is due substantially to its slagging. The object of the present study is to examine the effect of the change in oxygen potential on lead contained in slag. The molten silicate slag was brought into equilibrium with lead in a silica crucible at 1,200°, 1,250° and 1,300℃. The change in oxygen potential was achieved by varying CO_2 : CO gas mixture carried over the samples in composition from 0.157 : 1 to 25.66 : 1. The composition of the slag used corresponds to point K in the diagram FeO-SiO_2-CaO ; that is, 45.5% FeO, 43.0% SiO_2 and 11.5% CaO, which is close in composition to the slag saturated with silica. Subsequently the amounts of lead dissolved in the slags were determined by chemical analyses with rapidly cooled samples. The results obtained are as follows : (1) When the CO_2 : CO ratio is less than about 18 : 1〜22 : 1 (1,200°〜1,300℃), the contents of lead dissolved in slags increase gradually from 0.2〜0.4% to 0.5〜1.0% with the CO_2 : CO ratio and when it exceeds the ratio above mentioned, the contents of lead increase rapidly. (2) In constant CO_2 : CO ratio, increasing temperature increases the contents of lead dissolved in slags. (3) The greater part of lead dissolved in slag appears to exist in the form of oxide (including silicate), but metallic lead also dissolves. It the lowest CO_2 : CO ratio, where the system is nearly saturated with γ-Fe, the amounts on metallic lead dissolved in slag attain to about 50% of the total amounts of lead in slag. With an increase in CO_2 : CO ratio, the amount of lead in the form of oxide increases greatly, whilst the lead in metallic form remains practically constant. (4) The concentration of lead dissolved in slag is proportional to the square root of the partial pressure of oxygen in a range of low concentration. From this, it is infered that the solubility of oxygen in molten lead obeys Sievert's Law for dilute solution. The results thus obtained are applied to explaining some phenomena in the lead smelting in practice.
- 東北大学の論文
- 1957-07-30