Abstract
Dephosphorization of manganese alloy ([Mn]i: 5-60%, [P]i: 0.1-0.2%) was tested with flux containing various carbonate of basic oxide, by a 70 kg scale experiment.
(1) Dephosphorization hardly proceeded with flux containing CaCO3. In the case of treatment with flux containing Na2CO3 or Li2CO3, rate of dephosphorization was also low. On the other hand, the rate of dephosphorization with flux containing BaCO3 was comparatively high, and rephosphorization did not occur. So detailed experiments were done with flux containing BaCO3.
(2) In the case of treatment of high manganese alloy, the rate of dephosphorization was higher without adding BaCl2 than with BaCl2. This result is different from that for high chromium alloy. The reason is that MnO formed reduces the melting temperature of slag.
(3) The desirable conditions for dephosphorization with BaCO3 were: (i) lower temperature (ii) [%C] a little lower than the saturation value and (iii) preventing contamination by SiO2 and so on in order to keep (%BaO) as high as possible.
(4) It was effective to control oxygen potential of atmosphere or flux injection in order to make (%MnO) appropriate (20-40%).
(5) (P)/[P] of 15-20 was expected for dephosphorization of ordinary ferromanganese with BaCO3 at about 1 300°C.
