METHOD FOR PREPARING METALLIC TITANIUM USING TITANIUM-CONTAINING OXIDE SLAG

Abstract

The titanium-containing oxide slag, low-purity silicon and slagging fluxes are subject to reduction smelting together, and a bulk SiTi intermediate alloy is obtained by slag-metal separation; the obtained bulk SiTi intermediate alloy is crushed into SiTi intermediate alloy particles; and the obtained SiTi intermediate alloy particles are used as an anode, metallic molybdenum or metallic nickel as a cathode, metallic titanium as a reference electrode, and NaClKClNaF together with small amounts of Na.sub.3TiF.sub.6 or K.sub.3TiF.sub.6 as a molten salt, to carry out the electrolysis under a high-purity argon atmosphere at a temperature of 973 K. Ti in the SiTi intermediate alloy particles dissolved at the anode and deposited at the cathode, while Si in the SiTi intermediate alloy particles fell off from the anode as metallic silicon powder.

Claims

1. A method for preparing metallic titanium using titanium-containing oxide slag, comprising the following steps: step 1, performing reduction smelting on titanium-containing oxide slag, low-purity silicon and slagging fluxes together at a temperature of 1773 K under an inert atmosphere for more than 4 hours, and performing slag-metal separation to obtain a bulk SiTi intermediate alloy and a residual slag; and controlling a mass ratio of the titanium-containing oxide slag to the low-purity silicon during the reduction smelting, so that main phases in the obtained bulk SiTi intermediate alloy are titanium-silicon intermetallic compounds TiSix, 0<x?2; step 2, crushing the bulk SiTi intermediate alloy obtained in the step 1 into SiTi intermediate alloy particles with a particle size less than 4 mm; and step 3, using the SiTi intermediate alloy particles obtained in the step 2 as an anode, metallic molybdenum or metallic nickel as a cathode, metallic titanium as a reference electrode, and NaClKClNaF as a molten salt, adding Na.sub.3TiF.sub.6 or K.sub.3TiF.sub.6 to the molten salt for controlling a valence state of titanium to +3 during molten salt electrolysis, and performing molten salt electrolysis under a high-purity argon atmosphere at a temperature of 973 K, under this experimental condition, Ti in the SiTi intermediate alloy particles dissolved at the anode and deposited at the cathode, while Si in the SiTi intermediate alloy particles fell off from the anode as metallic silicon powder.

2. The method for preparing metallic titanium using titanium-containing oxide slag according to claim 1, wherein the titanium-containing oxide slag in the step 1 is oxide slag or scrap containing TiO.sub.2, comprising titanium-containing blast furnace slag or a spent SCR catalyst.

3. The method for preparing metallic titanium using titanium-containing oxide slag according to claim 1, wherein the low-purity silicon in the step 1 is a silicon material with metallic silicon as a main component, comprising a silicon alloy, industrial silicon or diamond wire saw silicon powder (Si sludge) generated from the photovoltaic industry.

4. The method for preparing metallic titanium using titanium-containing oxide slag according to claim 1, wherein the slagging fluxes in the step 1 is a mixture of one or more of CaO, SiO.sub.2, MgO and Al.sub.2O.sub.3 in a suitable proportion.

5. The method for preparing metallic titanium using titanium-containing oxide slag according to claim 1, wherein a ratio of NaCl, KCl and NaF in the NaClKClNaF molten salt in the step 3 is not limited.

6. The method for preparing metallic titanium using titanium-containing oxide slag according to claim 5, wherein a molar ratio of NaCl:KCl:NaF in the NaClKClNaF molten salt is 50.6:49.4:5.

7. The method for preparing metallic titanium using titanium-containing oxide slag according to claim 1, wherein Na.sub.3TiF.sub.6 or K.sub.3TiF.sub.6 is added to the molten salt in the step 3 in any molar percentage.

8. The method for preparing metallic titanium using titanium-containing oxide slag according to claim 7, wherein Na.sub.3TiF.sub.6 or K.sub.3TiF.sub.6 is added to the molten salt in the step 3 in a molar percentage of 1 mol %.

9. The method for preparing metallic titanium using titanium-containing oxide slag according to claim 1, wherein the molten salt electrolysis in the step 3 is performed by a galvanostatic method or a potentiostatic method.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The sole FIGURE is a schematic flow diagram of the present invention.

DESCRIPTION OF THE EMBODIMENTS

[0023] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

Embodiment 1

[0024] As shown in the sole FIGURE, the method for preparing metallic titanium using titanium-containing oxide slag comprised the following steps: [0025] step 1, titanium-containing oxide slag (titanium-containing blast furnace slag from Panzhihua region, with a TiO.sub.2 content of 20 wt. %), low-purity silicon (industrial silicon, with a Si content of 99.3 wt. %) and a slagging flux (MgO) were subject to reduction smelting together at a temperature of 1773 K under an argon atmosphere for 4 hours, and a bulk SiTi intermediate alloy and a residual slag were obtained by slag-metal separation. During the reduction smelting, a mass ratio of the titanium-containing oxide slag to the low-purity silicon was controlled to be 10:3, and the MgO was added in such an amount to saturate the MgO in the titanium-containing blast furnace slag. The main phase in the bulk SiTi intermediate alloy was a titanium-silicon intermetallic compound TiSi.sub.2 with a Ti content of 39 wt. %; [0026] step 2, the bulk SiTi intermediate alloy obtained in the step 1 was crushed into SiTi intermediate alloy particles with a particle size less than 4 mm; [0027] step 3, the SiTi intermediate alloy particles obtained in the step 2 were used as an anode, metallic molybdenum as a cathode, metallic titanium as a reference electrode, NaClKClNaF (with a molar ratio of NaCl:KCl:NaF being 50.6:49.4:5) as a molten salt, and 1 mol % Na.sub.3TiF was added to the molten salt to control a valence state of titanium to +3 during molten salt electrolysis which was carried out under a high-purity argon atmosphere (99.999%) at a temperature of 973 K by a potentiostatic method (with a constant potential of 400 mV). In the electrochemical process of the molten salt, Ti in the SiTi intermediate alloy particles dissolved at the anode and deposited at the cathode, while Si in the SiTi intermediate alloy particles fell off from the anode as metallic silicon powder; and [0028] step 4, the anode and the cathode in the step 3 were taken out of the molten salt under high-purity argon (99.999%), and the metallic silicon powder and the metallic titanium can be obtained below the anode and at the cathode respectively.

Embodiment 2

[0029] As shown in the sole FIGURE, the method for preparing metallic titanium using titanium-containing oxide slag comprised the following steps: [0030] step 1, titanium-containing oxide slag (titanium-containing blast furnace slag from Panzhihua region, with a TiO.sub.2 content of 20 wt. %), low-purity silicon (an eutectic silicon-titanium alloy, with a Si content of 75.5 wt. % and a Ti content of 21.6 wt. %) and a slagging flux (MgO) were subject to reduction smelting together at a temperature of 1773 K under an argon atmosphere for 4 hours, and a bulk SiTi intermediate alloy and a residual slag were obtained by slag-metal separation. During the reduction smelting, a mass ratio of the titanium-containing oxide slag to the low-purity silicon was controlled to be 3:1, and the MgO was added in such an amount to saturate the MgO in the titanium-containing blast furnace slag. The main phases in the bulk SiTi intermediate alloy were titanium-silicon intermetallic compounds TiSi and TiSi.sub.2 with a Ti content of 60.2 wt. %; [0031] step 2, the bulk SiTi intermediate alloy obtained in the step 1 was crushed into SiTi intermediate alloy particles with a particle size less than 4 mm; [0032] step 3, the SiTi intermediate alloy particles obtained in the step 2 were used as an anode, metallic nickel as a cathode, metallic titanium as a reference electrode, NaClKClNaF (with a molar ratio of NaCl:KCl:NaF being 50.6:49.4:5) as a molten salt, and 1 mol % Na.sub.3TiF was added to the molten salt to control a valence state of titanium to +3 during molten salt electrolysis which was carried out under a high-purity argon atmosphere (99.999%) at a temperature of 973 K by a potentiostatic method (with a constant potential of 300 mV). In the electrochemical process of the molten salt, Ti in the SiTi intermediate alloy particles dissolved at the anode and deposited at the cathode, while Si in the SiTi intermediate alloy particles fell off from the anode as metallic silicon powder; and [0033] step 4, the anode and the cathode in the step 3 were taken out of the molten salt under high-purity argon (99.999%), and the metallic silicon powder and the metallic titanium can be obtained below the anode and at the cathode respectively.

Embodiment 3

[0034] As shown in the sole FIGURE, the method for preparing metallic titanium using titanium-containing oxide slag comprised the following steps: [0035] step 1, titanium-containing oxide slag (a spent SCR catalyst, with a TiO.sub.2 content of 84.9 wt. %), diamond wire saw silicon powder (Si sludge, with a Si content of 90.2 wt. %) generated from the photovoltaic industry, and slagging fluxes (CaO, SiO.sub.2 and MgO) were subject to reduction smelting together at a temperature of 1773 K under an argon atmosphere for 4 hours, and a bulk SiTi intermediate alloy and a residual slag were obtained by slag-metal separation. During the reduction smelting, a mass ratio of the titanium-containing oxide slag to the diamond wire saw silicon powder was controlled to be 2:1, and CaO, SiO.sub.2 and MgO were added in such an amount that composition of the initial slag before reduction melting was 20 wt % CaO, 4 wt % SiO.sub.2, 56 wt % TiO.sub.2 and 20 wt % MgO. The main phases in the bulk SiTi intermediate alloy were titanium-silicon intermetallic compounds TiSi and TiSi.sub.2 with a Ti content of 53.7 wt. %; [0036] step 2, the bulk SiTi intermediate alloy obtained in the step 1 was crushed into SiTi intermediate alloy particles with a particle size less than 4 mm; [0037] step 3, the SiTi intermediate alloy particles obtained in the step 2 were used as an anode, metallic nickel as a cathode, metallic titanium as a reference electrode, NaClKClNaF (with a molar ratio of NaCl:KCl:NaF being 50.6:49.4:5) as a molten salt, and 1 mol % K.sub.3TiF.sub.6 was added to the molten salt to control a valence state of titanium to +3 during molten salt electrolysis which was carried out under a high-purity argon atmosphere (99.999%) at a temperature of 973 K by a potentiostatic method (with a constant potential of 350 mV). In the electrochemical process of the molten salt, Ti in the SiTi intermediate alloy particles dissolved at the anode and deposited at the cathode, while Si in the SiTi intermediate alloy particles fell off from the anode as metallic silicon powder; and [0038] step 4, the anode and the cathode in the step 3 were taken out of the molten salt under high-purity argon (99.999%) to obtain the metallic silicon powder and the metallic titanium below the anode and at the cathode respectively.

[0039] Although the embodiments of the present invention have been described in detail with reference to the accompanying drawings, the present invention is not limited thereto, and various modification may be made within the knowledge of those of ordinary skill in the art without departing from the spirit of the present invention.