JPS58126939A - Molybdenum selective dissolution - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Hungarian Budapest, 1325, pat1ut56
A Hungarian research institute, the Institute of Industrial Physics of the Hungarian Academy of Sciences (the RK8 TUTI!
t FORTIOHNIOAL PHY8I08 0
FTHE)! UIJGARIAN AC! A
The following disclosure seeks to describe in detail the invention and methods of carrying it out, for which the patent is sought.

The present invention relates to a method for selectively melting molybdenum when tungsten is present, and in particular to a method for melting molybdenum cores of tungsten coils.

Tungsten coils for incandescent lamps are usually made by wrapping tungsten fibers or coils of fiber around a core of molybdenum wire. To recover the mechanically deformed tungsten wire, the coil is annealed at a temperature of approximately 1500'C. The recovered coil retains its shape even after the molybdenum core is melted.

As a result of the winding process, the tungsten wire is pressed against the molybdenum core, so that the two metals are in contact not only with a line but also with a large surface area. During recovery annealing,
A certain amount of both metals diffuses into the metal on the other side of the area in contact with each other.

To melt molybdenum core metal, the usual method is, for example, at a volume ratio of 5:! A mixture of concentrated nitric acid, concentrated sulfuric acid and water of 1:2 is used (e.g. J, M, van
Liempt: Recuell (1611Tv
avaux Ohimiquea des Pays-B
as, 'I', 45 ss 7/B, 508~
521, 1926), that the weight loss of various types of tungsten coils during the melting process using such above-mentioned solutions is on average about 4% by weight. The inconsistency of the weight loss itself and its value is due to local changes in the composition of the solvent and its temperature, the different chemical resistance of the alloy to the solvent, and the Mo-W alloy layer formed during annealing. There are various reasons such as local variations in the composition of

A significant disadvantage of this process is that considerable amounts of nitrogen oxide 1 are generated from nitric acid and their mixtures during the dissolution process. The so-called nitrous gas is extremely corrosive and extremely dangerous to the environment. It is difficult or almost impossible to eliminate this effect without necessarily incurring considerable expense.

This method also has another disadvantage, namely that in the process of recovering the H0O3 useful content from the solvent, by-products are created which cannot be mixed into the regular sewerage system.

The present invention is a method for dissolving molybdenum in the presence of tungsten, specifically molybdenum mandrels, by using a peroxide-bound oxygen-containing compound. Advantageously, the acidic solution uses a selective catalyst, preferably ferric chloride, to a greater or lesser extent.

When such catalysts are present, hydrogen peroxide soluble peroxyacids or their salts, and superoxides or mixtures thereof have been employed with good results.

It has long been known that moderately concentrated aqueous H2O2 solutions gradually dissolve both tungsten and molybdenum, but the difference in dissolution rate that allows molybdenum to be selectively dissolved was not yet known. .

The present invention contains catalysts, such as IFe" ions, which do not affect the rate of dissolution of tungsten in H2O2, but increase the rate of dissolution of molybdenum by several orders of magnitude in the absence of any external solvent. Because of these differences, tungsten coils can be replaced with only about 1 to 2 weight losses over molybdenum cored metals within industrially acceptable consumption times. can be dissolved.

In some cases, the peroxide concentration of the solvent can be adapted to the specific surface area of the molybdenum, i.e. the thickness of the wire, and the rate of dissolution can be controlled by dropping the solvent into the reaction vessel to achieve the desired result5. I found it useful.

! By using organic or inorganic acids such as (2so,, HNO3, HOt, H(!tO,, acetic acid, tartaric acid, or various mixtures of these), the ... value of the solvent can be reduced to -0,5... - It has also been found that maintaining it in the range of +2.0 is extremely advantageous in reaching the optimum reaction rate.H,80, has been found to be the most suitable.

Selective catalysts such as those that break down peroxide bonds, e.g. F'
It has been industrially advantageous to use ferric compounds, such as eO1,3. The dissolution rate of molybdenum can be controlled within a wide range by the concentration of the catalyst. The following elements, Fe, Ou, Tt, Ag, Pb, (!r,
It has been found that the compounds Ni, B1, To, Oe, Ti, VlMn, 06, or mixtures of such compounds can be used with good results to control the reaction.

Substances that suppress tungsten waste in bath salts,
For example, the progress of the process described in this invention can be enhanced by using perchloric acid or its salts, chromic acid or its salts.

The dissolution rate of molybdenum is highly dependent on the temperature of the solvent. A range of 25°C to 35°C was found to be the optimum temperature to minimize tungsten dissolution. It is therefore recommended to limit the temperature by cooling.

In order to reduce the loss of oxygen due to spontaneous decomposition of peroxide bonds, it is advantageous to carry out the dissolution in a pressurized closed vessel.

Contrary to HIJo 3~H21304-H2O solvent,
It is an important advantage of the invention that no by-products are generated which may pose any danger to the environment.

The unique advantage of the method of the present invention is that by using FeOt3 catalyst and H2BO3 to control the ... value of the solvent, the dissolved molybdenum can be recovered in the form of MoO3, and the remainder of the solution is free from environmental pollution. It is completely harmless.

Some examples of practical applications of the invention are given below.

Example 1 Contains a Mo core metal whose weight is 4 times heavier than the weight of W.
For example, 1000 W coil pieces with a W coil of 10 mm and a Mo core of 40~ are prepared with the following composition: HOI 1% and lPe0t3.6HaO0,1'16
into a solution of 60% H2O2'500α3 containing . A vigorous reaction begins already at room temperature, but this can be controlled by keeping the temperature below 4.5° C. with water cooling. Dissolution of the mandrel takes approximately 15-25 minutes and leaves a solution containing dissolved brown peroxymolybdic acid outside the clean W coil. Separate the coil and wash it with a dilute acid solution, clean water and finally with ammonium hydroxide solution before drying. The surface of the coils has a glossy character, the weight loss is up to 6 inches, and the variation in their weight corresponds to the original variation.

Example 2 The same quantity and type of coils as described in Example 1 were used.
600 crn3 of a solution containing 1 g of ex(SO2)s and 2 g of perchloric acid. Concentration 60 while cooling with water
Htao250 Q m3 of water at a temperature of 65°
into the solution at a rate not higher than C.

After this panning process, the coil is treated as described in Example 1. The coil has a glossy surface characteristic and a maximum 1-year loss of 2%. The weight variation corresponds to the original variation.

Example 6 The same amount and type of coils as described in Example 1 were used in the following (al Fe063- HCI (1)l Fe2(S04)3- H2S"4(cl
'F8(NO3)3-HNO5((11Fe(O
to4)5- HCl0゜(5+ v e c13-
A solution containing 1% Fe” and 3% acid according to tartaric acid 600
Put it in α3. A 30% concentrated H202 solution is added dropwise to each sample at such a rate that the temperature does not rise above 65°C. Once this process is complete, the coil is processed as described in Example 1. The process parameters are summarized in the table below.

Example 4 The coil according to Example 1 was placed in a pressurized pot having a volume of 2000 cm3. A pressure gauge and pressure control pulp are attached to the container. 'lPe013・,4u2o O,2'1
Concentration 6 containing 6 and U I'28040.5%
0% HsOa 300[3] is cooled to 10° C. and poured into a container. Seal the container, gradually and carefully heat up to 30℃ to let the reaction open, cool and control, keep the temperature at 30℃ and the pressure at 10 atmospheres with pulp ■ The dissolution time is about 20 minutes. . After opening the pulp, the coil was prepared in Example 1.
Process as described in . The weight loss of the coil is 1.4
%.

Example 5 1000 coils for vacuum lamps, where the weight of the MO mandrel is lighter than the weight of W, for example, the weight of the coil is 7 yny and the weight of the mandrel is 3.
% and 1% H2SO4 in 120OsP. Add to this 60 tb solution of ammonium peroxysulfate 3
00 cM' is added dropwise at a rate that keeps the temperature below 40°C. Processing takes approximately 20 minutes. The coil is processed as described in Example 1. The weight loss is 0.8%.

Example 6 The coil described in Example 1 was prepared with the following composition, Tt2 (SO
4) Add a solution of 30.1% CuSO, 0.02% H2So, 391 to 500 g. H2o at a concentration of 30% at a rate that does not raise the temperature of the solution above 35°C! The I solution is cooled and added dropwise into a reaction vessel. The process is finished (about 3
At 0 min), the coils are separated and processed as described in Example 1. The weight loss of this is 3%.

Agent Asamura Hao 4 other people

Claims (1)

[Claims] (1) When tungsten is present, dissolution is carried out with an acidic solution of a compound containing oxygen in the peroxide bond phase, and a catalyst that promotes the dissolution of molybdenum is used. Existing methods for selectively melting molybdenum, especially molybdenum cores of tungsten coils for incandescent lamps. (2: Those described in item (1) above, where the oxygen-containing compound having a peroxide bond is hydrogen peroxide, also apply (
3) The compound containing oxygen having a peroxide bond is any one of hydrogen peroxide, a peroxy acid, a salt of a peroxy acid, a superoxide, or any mixture thereof (described in item 11). (4+) The process according to paragraphs (11 to 3) above, which involves dissolving molybdenum in an aqueous medium. , the method according to the above items (1) to (41), wherein the acidity of the solution is maintained within the pH range of -0, 5...+2.0. (6) Selective peroxide binding (7) For the decomposition of peroxide bonds, it is advantageous to use F e 013 as an iron compound as a catalyst. is the element Pa, (u,
Tt. Ag, Fb, Ni, B1, To, (e, Ti, V,
The method according to items (1) to (5) above, wherein a compound of MJOd or a mixture of compounds is used as a selective catalyst. (8) The method according to paragraphs 111 to 7 above, wherein sulfuric acid, nitric acid, hydrochloric acid, perchloric acid, acetic acid, tartaric acid, or any mixture thereof is used to control the... value of the solution. Method. (In order to suppress the dissolution of tungsten, perchloric acid or its salt, or chromic acid or its salt is present, and molybdenum is dissolved. The method according to paragraphs (1) to (9) above, wherein the temperature of the aO solution is below 45°C, advantageously between 25°C and 35°C. Dissolving molybdenum in a closed container,
Method 0 described in Section 11 to Section 00 above