Evaluation of Isothermal Separating Perovskite Phase from CaO-TiO 2 -SiO 2 -Al 2 O 3 -MgO Melt by Super Gravity
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tanium bearing blast furnace slag, a typical manmade resource, can hardly resort to a traditional separating technique to separate the perovskite phase from the slag, resulting from the dispersed distribution of the titanium component in various mineral phases, very fine grains ( 0 rÆmin–1, substituting R = 0.25 m, g = 9.80 m/s2 and the constant p = 3.14 into Eq. [1]. Hence, G ¼ 2:80 104 N2 An amount of 20 g of the pretreated slag was put into the filter (ID = 19 mm) with the pore size d = 0.5 mm as illustrated in Figure 1 and heated to 1563 K (1290 °C) for heat preservation; then the centrifugal apparatus was started and adjusted to the specified angular velocity of 1465 rÆmin–1, namely, G = 600 at the constant 1563 K (1290 °C) for 5 minutes. Afterward, the centrifugal apparatus was shut off and taken out of the graphite crucible, and finally water quenched the slag. The samples held on the filter and gone through the filter were sectioned longitudinally along the center axis. One was characterized by X-ray diffraction (TTRIII from Rigaku Corporation) and X-ray fluorescence (XRF-1800X from Shimadzu Corporation) to obtain the respective mineral composition and chemical component, while the other was measured on the scanning electron micrograph (SEM) and energy disperse spectrum (EDS; ZEISS EVO 18) to gain morphology of the products. Simultaneously, the parallel experiment was carried out at 1563 K (1290 °C) for 5 minutes without centrifugal separation, and the sample achieved in this process was called a parallel sample. Figure 2 shows vertical profiles of the sample obtained by centrifugal separation with the parameter VOLUME 45B, AUGUST 2014—1171
Table I.
Five Compositions of the Slag (Mass Fraction, Pct)
CaO
SiO2
TiO2
Al2O3
MgO
Sum
Basicity
33.07
25.44
23.34
11.08
7.06
100
1.3
Fig. 1—Schematic diagram of centrifugal separation apparatus. 1. Counterweight; 2. Centrifugal axis; 3. Base; 4. Graphite crucible; 5. Gangue melt before centrifugal separation; 6. Resistance coil; 7. Gangue melt after centrifugal separation; 8. Filter; 9. Perovskite crystals after centrifugal separation; 10. Perovskite crystals before centrifugal separation; 11. Thermocouple; 12. Horizontal rotor; 13. Conductive slipping; 14. Temperature controller.
Fig. 2—Vertical profile of the samples obtained by centrifugal separation compared with the parallel sample: (a) G = 1, t = 5 min, T = 1563 K (1290 °C); (b) G = 600, t = 5 min, T = 1563 K (1290 °C).
1172—VOLUME 45B, AUGUST 2014
METALLURGICAL AND MATERIALS TRANSACTIONS B
of G = 600, t = 5 minutes, T = 1563 K (1290 °C) compared with the parallel sample at the gravity coefficient G = 1, t = 5 minutes, T = 1563 K (1290 °C). Obviously, the product held back on the filter appears white, with a large number of porosities, while the product put through the filter presents black, with a glassy state. However, the uniform structure presents in the parallel sample as shown in Figure 2(a). Combined with the X-ray diffraction analysis as shown in Figure 3, almost all of the perovskite phase is held
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