As a means of preventing hydration of lime, a partial carbonation method is tried and the condition for the carbonation and properties of carbonated lime are investigated.
(1) The course of carbonation is expressed by ΔW
CO2=kt
n (ΔW
CO2: weight increase by carbonation, t: time, k, n, : constants depending on temperature, CO
2% in atmosphere and so on). Beyond a value of W
CO2, which depends on temperature, the rate of weight increase becomes small abruptly. In order to prevent the hydration effectively, lime at the end of CO
2-treatment must reach this state.
(2) The degree of hydration of lime treated in an adequate condition (ΔW
CO2: 5-7%) is 1/10 to 1/20 of that of ordinary lime.
(3) Hydrogen content in molten steel does not increase during fluxing of CO
2-treated lime. In an arc furnace, however, in which hydrogen is apt to be absorbed from atmosphere, it is desirable to control the arc atmosphere as well as to use CO
2-treated lime.
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