METHOD OF PRODUCING TITANIUM AND TITANIUM ALLOY NANOPOWDER FROM TITANIUM-CONTAINING SLAG THROUGH SHORTENED PROCESS

Abstract

Disclosed is a method of producing titanium and titanium alloy nanopowder from titanium-containing slag through a shortened process. The method includes: (1) subjecting titanium-containing slag to high-temperature oxidation and enrichment and then melting to precipitate titanium-enriched slag; (2) subjecting the titanium-enriched slag to pulverization and gravity flotation; (3) carrying out secondary enrichment; (4) preparing a molten salt reaction system; (5) synthesizing titanium and salt-containing titanium alloy nanopowder by reduction reaction; and (6) vacuum filtering, pickling, washing and vacuum drying the salt-containing titanium alloy nanopowder; and then separating titanium alloy nanopowder from the molten salt. Using the present method, the titanium-containing slag can be continuously treated to produce titanium and titanium alloy nanopowder. It requires a shortened process, a simple equipment and low energy consumption. The process is environmentally friendly and produces excellent products without solids, gas or liquids that are harmful to environment.

Claims

1. A method of producing titanium and titanium alloy nanopowder from titanium-containing slag through a shortened process, comprising: 1) mixing titanium-containing slag A with a modifier B in a reaction vessel; heating the reaction vessel to a reaction temperature for oxidation and enrichment, titanium in the titanium-containing slag A being formed into TiO.sub.3.sup.2 by the modifier B; and then cooling to precipitate titanium-enriched slag containing titanate C; 2) subjecting the titanium-enriched slag obtained in step 1) to pulverization, gravity flotation and drying to separate the titanium-enriched slag from other impure ores; 3) repeating steps 1) and 2) to improve purity of the titanate C as an intermediate; 4) mixing the titanate C obtained in step 3) and a molten salt medium; dehydrating under vacuum and then melting at 550-900 C. to form a molten salt reaction system, titanium in the mixture being formed into TiO.sub.3.sup.2; 5) adding a reducing agent into the molten salt reaction system obtained in step 4) for thermal reduction in an inert gas at 400-900 C. to synthesize titanium and salt-containing titanium alloy nanopowder; and 6) vacuum filtering, pickling, washing and vacuum drying the salt-containing titanium alloy nanopowder obtained in step 5); and then separating the titanium alloy nanopowder from the salt-containing titanium alloy nanopowder to obtain titanium and titanium alloy nanopowder.

2. The method of claim 1, wherein in step 1) the modifier B is selected from one or more of Na.sub.2O, CaO, K.sub.2O, NaOH, Ca(OH).sub.2, KOH, Na.sub.2CO.sub.3, Ca.sub.2CO.sub.3 and K.sub.2CO.sub.3.

3. The method of claim 1, wherein in step 1) the titanate C is selected from one or more of Na.sub.2TiO.sub.3, CaTiO.sub.3, K.sub.2TiO.sub.3 and TiO.sub.2.

4. The method of claim 1, wherein in step 1) the oxidation and enrichment is carried out at a temperature of 1100-1500 C. for 5-10 hours.

5. The method of claim 1, wherein in step 2) the titanium-enriched slag is pulverized to 100-300 mesh, and the drying is carried out at 100-300 C.

6. The method of claim 1, wherein in step 4), a vacuum degree is 0.2-0.3 MPa; a mole percentage of the titanate C is 1-10 mol %; the molten salt medium comprises a compound D having a mole percentage of 50-100 mol % and a compound E having a mole percentage of 0-40 mol %; and a dehydrating temperature is 150-350 C.

7. The method of claim 1, wherein in step 5) the reducing agent is selected from sodium, calcium or magnesium, and the inert gas is argon at a flow rate of 1-30 mL/s.

8. The method of claim 1, wherein in step 6) a vacuum drying temperature is 30-50 C., and a vacuum degree is 0.2-0.5 MPa.

9. The method of claim 6, wherein the compound D is selected from one or more of CaCl.sub.2, NaF and KF; and the compound E is selected from one or more of NaCl, KCl, LiCl and NaAlO.sub.2.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The present disclosure will be further described in detail with reference to the accompanying drawings and embodiments.

[0030] FIG. 1 is a flow chart showing a method according to the present invention.

[0031] FIG. 2 is a schematic diagram showing X-ray Diffraction (XRD) pattern of phase analysis on Ti nanopowder prepared in Example 1 according to the present invention.

[0032] FIG. 3 is a Field Emission Scanning Electron Microscopy (FESEM) image showing surface appearance of Ti nanopowder prepared in Example 1 according to the present invention.

[0033] FIG. 4 is a schematic diagram of XRD pattern of phase analysis on TiAl alloy nanopowder prepared in Example 2 according to the present invention.

[0034] FIG. 5 is an FESEM image showing surface appearance of TiAl alloy nanopowder prepared in Example 2 according to the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS

[0035] The present disclosure is further described with reference to the following embodiments.

[0036] The present disclosure may adopt the conventional devices in the art for extraction, reduction and synthesis of titanium-containing slag through a short process. The following embodiments are carried out using the process shown in FIG. 1.

EXAMPLE 1

[0037] This embodiment illustrates a method of preparing Ti nanopowder using ilmenite (grade: 52%) through reduction reaction. 200 g of ilmenite and 33 g of CaO were uniformly mixed, and then pressed into a block and placed in a high-temperature furnace for oxidation and enrichment at 1350 C. for 7 hours. They were cooled to precipitate and were pulverized into powder having a size of 200 mesh when cooled to room temperature. The powder was subjected to gravity flotation to obtain titanium-enriched slag. The titanium-enriched slag was subjected to the secondary oxidation and enrichment at 1250 C. for 5 hours to obtain titanate (CaTiO.sub.3) as an intermediate during which a ratio of the titanium-enriched slag to CaO is 90:10 by weight. The intermediate was then mixed with a molten salt medium containing NaCl-60 mol %CaCl.sub.2 in a ratio of 10:90 by weight. The mixture was melted in a reaction furnace at 750 C. to form a molten salt reaction system. Calcium as a reducing agent was added for reduction for 6 hours to synthesize Ti nanopowder. After the reaction was completed, the furnace was decreased to room temperature. The calciothermic reduction is carried out under the protection of Ar gas. Finally, the resulting Ti nanopowder and the molten salt were washed in 3-5% dilute hydrochloric acid and distilled water, and then were filtered and vacuum dried at 35 C. with a vacuum degree of 0.4 MPa to separate the Ti nanopowder from the molten salt.

[0038] The purity of the prepared Ti nanopowder reaches 98.45 wt %. The particle size of the spherical agglomerated particles ranges from 100 to 250 nm. The XRD pattern of phase analysis and FESEM image of Ti nanopowder are shown in the FIGS. 2 and 3, respectively.

EXAMPLE 2

[0039] This embodiment illustrates a method of preparing TiAl alloy nanopowder using ilmenite (grade: 50%) through reduction reaction. 200 g of titanium concentrate and 52 g of CaCO.sub.3 were uniformly mixed, and then pressed into a block and placed in a high-temperature furnace at 1450 C. for oxidation and enrichment for 8 hours. They were cooled to precipitate and was pulverized into powder having a size of 200 mesh when cooled to room temperature. The powder was subjected to gravity flotation to obtain titanium-enriched slag. The titanium-enriched slag was subjected to the secondary oxidation and enrichment at 1350 C. for 6 hours to obtain titanate (CaTiO.sub.3) as an intermediate during which a ratio of the titanium-enriched slag to CaCO.sub.3 is 80:10 by weight. The intermediate was then mixed with a molten salt medium containing sodium aluminate and NaCl-52 mol % CaCl.sub.2 in a ratio of 6:4:90 by weight. The mixture was melted in a reaction furnace at 700 C. to form a molten salt reaction system. Sodium as a reducing agent was added for reduction for 8 hours to synthesize TiAl alloy nanopowder. After the reaction is completed, the furnace is cooled to room temperature, and the calciothermic reduction is carried out under the protection of Ar gas. Finally, the resulting TiAl alloy nanopowder and the molten salt were washed in 3-5% dilute hydrochloric acid and distilled water, and then were filtered and vacuum dried at 35 C. with a vacuum degree of 0.4 MPa to separate the TiAl alloy nanopowder from the molten salt.

[0040] The purity of the prepared TiAl alloy powder reaches 99.32 wt %. The particle size of spherical agglomerated particles ranges from 150 to 450 nm. The XRD pattern of phase analysis and FESEM image of TiAl alloy nanopowder are shown in FIGS. 4 and 5, respectively.

[0041] The above embodiments are only illustrative of the present invention, and the present invention is not limited thereto. It should be understood that any variations and modifications made by those skilled in the art within the spirit of the invention shall fall into the scope of the present disclosure.

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