|Budget Amount *help
¥2,200,000 (Direct Cost : ¥2,200,000)
Fiscal Year 1991 : ¥600,000 (Direct Cost : ¥600,000)
Fiscal Year 1990 : ¥400,000 (Direct Cost : ¥400,000)
Fiscal Year 1989 : ¥1,200,000 (Direct Cost : ¥1,200,000)
Purification of iron oxide obtained from Iron Precipitation of the Zinc leaching residues and the various iron ores with Na_2O - B_20_3 flux have been investigated by use of recrystallization method.
And, the effect of retention time at 1200ﾟC, cooling rate, iron oxid/flux ratio, CuO and NaF additions as a crystallization accelerator on size, purity and the yield of hematite crystals were tested.
Also, the Na_2O・2B_2O_3-Fe_2O_3 phase diagram which is related to the yield of hematite crystals from mixtures of iron ore and flux by use of recrystallization method was determined by differential thermal analysis.
The main results obtained are as follows :
In the case of purification of iron oxide(Fe_2O_3 : 74.59%, Zn : 0.60%, S : 4.49%, etc)obtained from Iron Precipitation of the Zinc leaching residues,
(1)The size of hematite crystals decreased with the increasing cooling rate from 1ﾟC to 10ﾟC/min.
(2)The purity of hematite crystals was about>99.8% of Fe_2O_3, and the contents of Zn, S, As were
300ppm, 7-20ppm and about 30ppm, respectively.
(3)The yield of hematite crystals increased up to>80% with increasing cooling rate, the iron oxide/flux ratio and with an increase of NaF addition.
In the case of purification of the various iron ores,
(1)The purity of hematite crystals was about>99.5% of Fe_2O_3.
(2)In the removal of impurities in iron ores with Na_2O・2B_2O_3 flux, AI, Si, Ca and Mg were remarkably decreased, and Ti was not removed.
(3)The yield of hematite crystals increased up to>80% with increasing cooling rate and the iron oxide/flux ratio.
In the determination of Na_2O-2B_2O_3-Fe_2O_3 phase diagram,
(1)Na_2O-2B_2O_3-Fe_2O_3 phase diagram was simple eutectic type, and eutectic temperature and eutectic composition were 693'C, 14% respectively.
(2)For example, the yield of hematite crystals calculated from Na_2O・2B_2O_3-Fe_2O_3 phase diagram in iron ores/flux ratio, 50%, is 72%, this value was about 10% lower than the actual yield of hematite crystals recognized in the purification of iron oxide obtained from Iron Precipitation of the Zinc leaching residues and the various iron ores with Na_2O・2B_2O_3 flux.
(3)Na_2O・2B_2O_3 is superior to Na_2O・B_2O_3 as the flux for purification of iron ores. Less