Method for preparing high-melting-point metal powder through multi-stage deep reduction

Patent metadata

Field	Value
Publication number	US-11241740-B2
Application number	US-201816498151-A
Country	US
Kind code	B2
Filing date	May 21, 2018
Priority date	May 23, 2017
Publication date	Feb 8, 2022
Grant date	Feb 8, 2022

Abstract

The invention relates to a method for preparing high-melting-point metal powder through multi-stage deep reduction, and belongs to the technical field of preparation of powder. The method includes the following steps of mixing dried high-melting-point metal oxide powder with magnesium powder and performing a self-propagating reaction, placing an intermediate product into a closed reaction kettle, leaching the intermediate product with hydrochloric acid as a leaching solution so as to obtain a low-valence oxide MexO precursor of the low-valence high-melting-point metal; uniformly mixing the precursor with calcium powder, pressing the mixture, placing the pressed mixture into a vacuum reduction furnace, heating the vacuum reduction furnace to 700-1200° C., performing deep reduction for 1-6 h, leaching a deep reduction product with hydrochloric acid as a leaching solution and performing treatment, so as to obtain the high-melting-point metal powder.

First claim

What is claimed is:

1. A method for preparing a high-melting-point metal powder through a multi-stage deep reduction, comprising the following steps:
step 1, performing a self-propagating reaction:
drying a high-melting-point metal oxide powder to obtain a dried high-melting-point metal oxide powder, mixing the dried high-melting-point metal oxide powder with magnesium (Mg) powder to obtain mixed materials, adding the mixed materials into a self-propagating reaction furnace to perform the self-propagating reaction, and performing cooling to obtain an intermediate product in which a low-valence oxide Me x O of a high-melting-point metal (Me) is dispersed in an MgO matrix,
wherein the intermediate product in which the low-valence oxide Me x O of the high-melting-point metal is dispersed in the MgO matrix is a mixture of low-valence high-melting-point metal oxides with a non-stoichiometric ratio,
x is 0.2-1,
the high-melting-point metal specifically comprises one or more of W, Mo, Ta, Nb, V, Zr, Hf and Re,
the high-melting-point metal oxide is one or a mixture of several kinds of WO 3 , MoO 3 , Ta 2 O 5 , Nb 2 O 5 , V 2 O 5 , ZrO 2 , HfO 2 and Re 2 O 7 , and
when the high-melting-point metal oxide is WO 3 , a mixing proportion in molar ratio of WO 3 to Mg is 1 to (0.8-1.2), when the high-melting-point metal oxide is MoO 3 , a mixing proportion in molar ratio of MoO 3 to Mg is 1 to (0.8-1.2), when the high-melting-point metal oxide is Ta 2 O 5 , a mixing proportion in molar ratio of Ta 2 O 5 to Mg is 1 to (2.7-3.3), when the high-melting-point metal oxide is Nb 2 O 5 , a mixing proportion in molar ratio of Nb 2 O 5 to Mg is 1 to (2.7-3.3), when the high-melting-point metal oxide is V 2 O 5 , a mixing proportion in molar ratio of V 2 O 5 to Mg is 1 to (2.7-3.3), when the high-melting-point metal oxide is ZrO 2 , a mixing proportion in molar ratio of ZrO 2 to Mg is 1 to (0.8-1.2), when the high-melting-point metal oxide is HfO 2 , a mixing proportion in molar ratio of HfO 2 to Mg is 1 to (0.8-1.2), and when the high-melting-point metal oxide is Re 2 O 7 , a mixing proportion in molar ratio of Re 2 O 7 to Mg is 1 to (2.7-3.3);

step 2, performing a primary leaching:
placing the intermediate product in which the low-valence oxide Me x O of the high-melting-point metal is dispersed in the MgO matrix into a closed reaction kettle, leaching the intermediate product with hydrochloric acid as a leaching solution to obtain a leaching solution and a leaching product, removing the leaching solution, washing the leaching product, and performing vacuum drying on the washed leaching product to obtain a low-valence oxide Me x O precursor of the low-valence high-melting-point metal, wherein a molar concentration of hydrochloric acid is 1-6 mol/L;

step 3, performing the multi-stage deep reduction:
uniformly mixing the low-valence oxide Me x O precursor of the low-valence high-melting-point metal with calcium (Ca) powder, performing pressing at 2-20 MPa to obtain a block blank, placing the block blank in a vacuum reduction furnace, performing heating to 700-1,200° C., performing a secondary deep reduction for 1-6 h, obtaining a block billet after the secondary deep reduction, and cooling the block billet along with the vacuum reduction furnace to obtain a deep reduction product, wherein a molar ratio is described as follows: Me x O:Ca=1:(1.5-3); and

step 4, performing a secondary leaching:
placing the deep reduction product in the closed reaction kettle, leaching the deep reduction product with hydrochloric acid as a leaching solution to obtain a filtrate and filter residues, removing the filtrate, washing the filter residues and performing vacuum drying to obtain a low-oxygen high-melting-point metal powder,
wherein a molar concentration of hydrochloric acid is 1-6 mol/L,
the low-oxygen high-melting-point metal powder comprises the following ingredients by percentage by mass of equal to or smaller than 0.8% of O, greater than or equal to 99% of the high-melting-point metal and a balance of inevitable impurities, and
a particle size of the low-oxygen high-melting-point metal powder is 5-60 μm.

2. The method according to claim 1 , wherein in the step 1, the drying is performed in a specific operation step of placing the high-melting-point metal oxide powder into a drying oven, and performing the drying at a temperature of 100-150° C. for 24 h or above.

3. The method according to claim 1 , wherein in the step 1, the mixed materials are treated in one of the following two ways before being added into the self-propagating reaction furnace:
a first treatment way comprises the following steps: pressing the mixed materials under 10-60 MPa to obtain a block blank, adding the block blank into the self-propagating reaction furnace and performing the self-propagating reaction; and
a second treatment way comprises the following steps: directly adding the mixed materials into the self-propagating reaction furnace without treatment and performing the self-propagating reaction.

4. The method according to claim 1 , wherein in the step 1, initiation modes of the self-propagating reaction are respectively a local ignition method and an overall heating method, wherein the local ignition method refers to heating a local part of the mixed materials by an electric heating wire in the self-propagating reaction furnace to initiate the self-propagating reaction; the overall heating method refers to raising a temperature of the whole mixed materials in the self-propagating reaction furnace until the self-propagating reaction occurs, and the temperature is controlled at 500-750° C.

5. The method according to claim 1 , wherein in the step 2, when the intermediate product is leached, diluted hydrochloric acid and the intermediate product are in cooperation in a manner that an adding amount of the diluted hydrochloric acid is 10-40 volume % in excess of the hydrochloric acid required by a reaction theory; and
in the step 2, a leaching temperature for leaching the intermediate product is 20-30° C., and a leaching time is 60-180 min.

6. The method according to claim 1 , wherein in the step 2, the low-valence oxide Me x O precursor of the low-valence high-melting-point metal comprises the following ingredients by percentage by mass of 5-20% of O, smaller than or equal to 0.5% of the inevitable impurities and a balance of the high-melting-point metal, wherein a particle size is 0.8-15 μm.

7. The method according to claim 1 , wherein in the step 2, the washing process and the vacuum drying process comprise the following specific steps: washing the leaching product without the leaching solution with water until a washing solution is neutral, and then drying the washed leaching product in a vacuum drying oven at a temperature of 20-30° C. for at least 24 h; and
the washing is performed with water and specifically refers to dynamic washing, in which the washing solution in a washing tank is kept at a constant water level in the washing process, fresh water with the same amount of a drained washing liquid is supplemented, and the leaching product is washed until the washing liquid is neutral.

8. The method according to claim 1 , wherein in the step 3, a reaction parameter for the secondary deep reduction lies in that heating is performed under the condition that the vacuum degree is less than or equal to 10 Pa.

9. The method according to claim 1 , wherein in the step 4, when the deep reduction product is leached, diluted hydrochloric acid and the deep reduction product are in cooperation in a manner that an adding amount of the diluted hydrochloric acid is 5-30 volume % in excess of the hydrochloric acid required by a reaction theory; and
in the step 4, a leaching temperatur

Assignees

• Univ Northeastern

Inventors

• Zhang Ting An
• Dou Zhihe
• Liu Yan
• Zhang Zimu
• Lv Guozhi
• Zhao Qiuyue
• Niu Liping
• Fu Daxue
• Zhang Weiguang

Classifications

• C22B34/20

  Obtaining niobium, tantalum or vanadium · CPC title

• B22F9/24 Primary

  starting from liquid metal compounds, e.g. solutions · CPC title

• C22B34/14 Primary

  Obtaining zirconium or hafnium {(treatment or purification of solutions by liquid-liquid extraction, by ion exchange or by adsorption C22B3/00, C01G25/003, C01G27/003)} · CPC title

• C22B5/04

  by aluminium, other metals or silicon · CPC title

• C22B34/00 Primary

  Obtaining refractory metals · CPC title