METHOD FOR PRODUCING HIGH-PURITY TUNGSTEN POWDER

WIPO Patent Application WO/2011/040400

A1

Disclosed is a method for producing a high-purity tungsten powder that has a phosphorus content of less than 1 ppm by weight, which is characterized in that: an ammonium tungstate solution that contains phosphorus, which is an impurity, in an amount of not less than 1 ppm by weight in terms of the inclusion in tungsten is used as a starting material; the ammonium tungstate solution is neutralized with hydrochloric acid at a temperature of 50°C or less to have a pH of 4 or more but less than 7, so that ammonium paratungstate undecahydrate crystals are precipitated; the resulting solution is heated to 70-90°C and filtered at a high temperature, so that ammonium paratungstate pentahydrate crystals are obtained; the ammonium paratungstate pentahydrate crystals are calcined so as to form tungsten oxide; and then the tungsten oxide is subjected to hydrogen reduction so as to obtain a high-purity tungsten powder. Also disclosed is a method for producing a high-purity tungsten powder that has a phosphorus content of not more than 0.4 ppm by weight, which is characterized in that the pH during the step of neutralization with hydrochloric acid is set at 4-6 (inclusive) and a high-purity tungsten powder is produced by the same procedure as described above. Consequently, the phosphorus content can be efficiently reduced.

JP2001217106	MAGNET COMPOSITION AND BONDED MAGNET USING THE SAME
JPWO2019239655	Manufacturing method of copper alloy powder, additive manufacturing and additive manufacturing, and various metal parts
JP2010192449	METHOD FOR PRODUCING HYDROGEN STORAGE ALLOY POWDER

SATO JIN (JP)
TAKEMOTO KOUICHI (JP)
SASAKI TAKESHI (JP)
OHNO MIKIO (JP)
OGURA JUNJI (JP)

PCT/JP2010/066810

April 07, 2011

September 28, 2010

Click for automatic bibliography generation  

JX NIPPON MINING & METALS CORP (JP)
JAPAN NEW METALS CO LTD (JP)
SATO JIN (JP)
TAKEMOTO KOUICHI (JP)
SASAKI TAKESHI (JP)
OHNO MIKIO (JP)
OGURA JUNJI (JP)

B22F1/00; B22F9/22; C22C27/04

WO2008092837A1	2008-08-07
WO2008092838A1	2008-08-07
WO2005073418A1	2005-08-11

JPS62108731A	1987-05-20
JPS61107728A	1986-05-26
JPH03150356A	1991-06-26
JPH06158300A	1994-06-07
JP2005307235A	2005-11-04
JPH01172226A	1989-07-07
JP3086447B1	2000-09-11

See also references of EP 2484463A4

OGOSHI ISAMU (JP)
Isamu Ogoshi (JP)

View/Download PDF      PDF Help

Previous Patent: RESIN COMPOSITION, PREPREG USING SAME, METAL FOIL WITH RESIN, ADHESIVE FILM, AND METAL-CLAD LAMINATE

Next Patent: CREDIT CARD FRAUD PREVENTION SYSTEM