7 - Phase Equilibrium and Minor-Element Distribution...

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Phase Equilibrium and Minor-Element Distribution between Ni 3 S 2 -FeS Matte and Calcium Ferrite Slag under High Partial Pressures of SO 2 J.M. FONT, M. HINO, and K. ITAGAKI Calcium ferrite slag has been successfully used in the copper smelting process, but no attempt has been made to use it in the nickel smelting process. The phase equilibrium and the distribution of minor elements between the Ni 3 S 2 -FeS matte and the CaO-FeO x –based slag (containing about 2 wt pct MgO) in a magnesia crucible were investigated at 1523 K under controlled partial pressures of S 2 ,O 2 , and SO 2 of 10.1, 50.7, and 101.3 kPa, respectively. The results were compared with those for the iron-silicate–based slag, and the following conclusions were obtained: (1) there is no significant difference in the solubility of nickel between both slags in the high-matte-grade range, (2) the dissolution of cobalt in the calcium ferrite slag is clearly smaller than that in the iron silicate slag, (3) detrimental arsenic, antimony, and bismuth are preferentially collected and fixed in the calcium ferrite slag rather than in the iron silicate slag, and (4) it is considered, with regard to technical feasibility, that the use of the calcium ferrite slag in a converting process of the Bessemer matte will have a prominent future for the nickel converting stage. I. INTRODUCTION Although the use of a CaO-FeO x slag (calcium ferrite slag) has been successfully practiced in the converting furnace of T HE conventional pyrometallurgical process of nickel the Mitsubishi continuous copper-making process, no sulfide ores consists of two stages of smelting and con- attempt has been reported on its use in the nickel converting verting. The concentrates are oxidized in the smelting stage process. The authors consider that there will be the possibil- to produce the Ni-Cu-Fe-S matte with 10 to 50 wt pct Ni ity to make use of this slag in making a new process of and the iron-silicate–based slag. The smelting furnace matte nickel converting. Therefore, it is of interest to compare the is further oxidized in the converting stage to produce the results for the phase equilibrium and the distribution of Ni-Cu-S matte, which has a very small content of iron of minor elements between the traditional iron-silicate–based less than 1 wt pct and high contents of nickel and copper, slag and the calcium ferrite–based slag. with 40 to 75 wt pct Ni and 5 to 50 wt pct Cu. [1] The contents In the present study, the phase equilibrium and the distri- of nickel and copper in the converting matte are dependent bution of minor elements between the Ni 3 S 2 -FeS matte cor- solely on their contents in the concentrate. responding to the iron-free matte and the CaO-FeO x –based The combination of intensive reactors with the use of slag (containing about 2 wt pct MgO) in a magnesia crucible oxygen or oxygen-enriched air has provided improved nickel were investigated at 1523 K under controlled partial pres- smelting and converting processes such as the INCO-Flash, sures of S 2 2 , and SO 2 of 10.1, 50.7, and 101.3 kPa. The
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This note was uploaded on 05/13/2011 for the course METALLURGY 1107 taught by Professor Hegurange during the Three '10 term at Murdoch.

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7 - Phase Equilibrium and Minor-Element Distribution...

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