JPS5992919A - Purification of molybdenum trioxide - 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 The present invention relates to a method for separating impurities such as rhenium, iron and iron from crude molybdenum trioxide. Molybdenum is a by-product of recovering copper from iron ore. Copper sulfide and molybdenum sulfide are separated from the gangue material, which is mostly quartz and clay, by flotation. Most methods selectively crush the copper to obtain a molybdenum concentrate containing 0.1-1.5% copper and most of the rhenium present in the ore. Since rhenium and copper are detrimental to most uses of molybdenum, it is desirable to remove as much rhenium and copper as possible from the final molybdenum concentrate. If the concentration of these substances exceeds a certain value, monobdenum refiners will be required to pay a fine. Also, rhenium always has a high value - the separation of dust improves the economics of beneficiation.

Since rhenium is usually present in the main part of the molybdenum lattice, it is concentrated with the molybdenum and is usually difficult to leach out before heat treatment. MoIJ budenite is converted into molybdenum oxide by heat treatment (roasting) and the original lattice is destroyed. During heating, rhenium in the molybutinite lattice is oxidized and volatile rhenium pentoxide is recovered from the off-gas. Generally, the acidic atmosphere in the furnace is insufficient to completely oxidize the rhenium. Therefore, a mixture of oxides is formed and remains with up to 50% of rhenium carbonate and monobutene. It also contains lower molybdenum oxide and impurities such as rhenium, copper, and iron.

In the present invention, the impure mixture of strong molybdenum oxide is referred to as crude molybdenum trioxide, and the term molybdic anhydride is used to refer to pure McO
Used for a.

In U.S. Pat. No. 3,816,588 and its divisional application, U.S. Pat. No. 3,891,521, αγtin is produced by molybdenite being oxidized and solubilized by leaching with an alkaline persulfate solution, and insoluble in rhenium. Discloses that it leaves a residue. The latter can be totally oxidized to rhenium pentoxide, which can be recovered by distillation from the undissolved retentate. Qarlin's method has three drawbacks = (1)
Leaching takes several days; (2) all of the leaching solution and oxidizer are consumed; (3) careful monitoring is required to ensure that the molybdenum is not contaminated with copper.

Alternatively, Lty, ke et al., U.S. Pat. No. 3,77
No. 0,414 discloses oxygen enrichment of the heat treatment atmosphere. This oxygen enrichment results in more complete volatilization of rhenium. Some of the rhenium still remaining in the calcined product is leached out, combined with off-gas rhenium, and purified by solvent extraction.

7'' May discloses in US Pat. No. 3,705,230 that molybdenum ore is calcined in the presence of calcium compounds such as calcined lime to produce calcium perrhenate and calcium molybdate, and the valuable materials of molybdenum and rhenium are released. Next, a method of leaching, acidification, and separation is disclosed. Although this method is effective, it is not economical because it consumes a lot of energy and uses sweet chemicals.

The present invention is a method for completely removing impurities in crude molybdenum trioxide by suspending the crude molybdenum trioxide in an aqueous mineral acid and aging it in the presence of an oxidizing agent. The aged slurry is separated into a solid portion of purified molybdic anhydride and an acid solution containing leached impurities. If desired, rhenium is recovered from the acid solution by standard methods such as solvent extraction, ion exchange, or dehydration and distillation.

This process is particularly effective in reducing the rhenium and copper content of crude molybdenum trioxide, avoiding the fines normally imposed, and may also remove other acid-soluble impurities such as iron compounds.

The impurity content of molybdenite ores and crude molybdenum trioxide varies over a wide range. Optimum operating conditions can be determined by economic factors that will be apparent to those skilled in the art, as all undesirable copper and rhenium need not be completely removed, but only need to be reduced in concentration to below regulatory limits. The tamp, leaching time and temperature, mineral acid and oxidizing agent concentrations are not critical and are interrelated.

If the liquid:solid ratio in the slurry is smaller than 90:10, the capacity is too large and is generally uneconomical;
If the size is too large, it will be difficult to handle and paste particles will easily form. The concentration of aqueous mineral acid is also not critical; crude molybdenum trioxide also tends to dissolve in concentrated acids such as commercially available 96s, -98' sulfuric acid. Such acids are not normally considered aqueous solutions.

In the present invention, the term aqueous mineral acid refers to mixtures of acids and water such that further dilution with water shows no substantial change in physical or chemical properties, such as sulfuric acid diluted by more than 35%. includes. Therefore, commercially available concentrated sulfuric acid that completely dissolves molybdenum trioxide is not an aqueous mineral acid for the purposes of this invention. Sulfuric acid, phosphoric acid, perchloric acid, and other mineral acids can be used in the present invention. Sulfuric acid is preferred because of its ease of availability and cheapness.

The acid concentration is preferably 0.1N (0.5% sulfuric acid) or more in terms of hydrogen ion concentration in order to completely dissolve impurities in the crude molybdenum trioxide. An acid concentration of hydrogen ion concentration of 6N or more may be used, but it has no further operational effect and is not economical unless the entire leaching solution is reused.

Although any known oxidizing agent may be used, it is usually undesirable to add ions that would contaminate the purified molybdenum trioxide.

From this point of view, oxygen and hydrogen peroxide are preferred. -! When using the preferred sulfuric acid in this method, monopersulfuric acid or dipersulfuric acid are also preferred. For dipersulfuric acid, add commercially available persulfates such as sodium persulfate! Can be formed in solution. On the reaction, the dipersulfuric acid has the effect of providing additional acid to the solution.

Since the molybdic anhydride in the crude molybdenum trioxide is sufficiently oxidized, sufficient oxidizing agent to oxidize the lower grade oxides present in the crude molybdenum trioxide is required to achieve the desired overall grade of modification. Just add .

It is preferred to maintain any detectable excess of oxidant throughout the ripening and oxidation steps.

Aging time and temperature are interdependent and non-critical, 60
℃, the time may be 1 hour or less, and there is no significant difference in extraction effect between 1 hour and 5 hours.

Impurities leached from molybdenum may be disposed of or recovered by known methods. For example, rhenium is
, 855°294, and the solvent extraction disclosed in U.S. Pat.
, 945,743, or by dehydrating the leachate and distilling rhenium pentoxide from the residue. Molybdenum dissolved in the leachate can be recovered by precipitation or solvent extraction.

Next, all embodiments of the present invention will be explained. This is an example and is not intended to limit the invention.

Example 1 A commercially available calcined crude molybdenum trioxide was mixed with 10% sulfuric acid and the mixture was mixed with 60% sulfuric acid. A 3:2 slurry IJ-i was prepared consisting of 100% crude molybdenum trioxide and 402% sulfuric acid, and 500 my/z phenol was added as an oxygen stabilizer. 6 slurry
It was heated to 0° C. and 85 ml of 10-thihydrogen peroxide was added in 9 equal portions over 1 hour to maintain a 450 mV to 500 mVtD potential as measured using an AQ/AgCl-calomel electrode system.

While the system was warm, it was filtered and the solids were washed and dried. The P solution was filtered again the next day, and all the solids were combined with the solids obtained from the first filtration.

The solid was essentially pure MoQa.H2O. The results are shown in Tables I and ■.

Examples 2 and 3 Using 10 ml of 10% hydrogen peroxide, after 1 hour the sample was
The method of Example 1 was followed except that it was divided into equal parts. One half was immediately filtered (Example 2), and the other half was further incubated at 60°C for 4 hours.
(Example 3).

Examples 4 and 5 Examples 2 and 3 were repeated except that no stabilizer was used.

The presence of a stabilizer was found to be necessary.

Examples 6 and 7 (7.0- fresh 50% persulfate instead of hydrogen peroxide)
Examples 4 and 5 were repeated except that IJum solution was used.

Examples 8 and 9 Examples 2 and 3 were repeated except that the partially leached pottery was treated with 10 times more Part 7.1 peroxide solution.

Example 1 A total of 201 calcined products of 10°302 was suspended in 10% sulfuric acid at 60°C. An acid solution made from 5.21 parts of sulfuric acid and 0.87 parts of hydrogen peroxide was added over a total of 1 hour. The reaction mixture is
After an hour it was filtered.

The data in Table I indicate that it is effective in recovering between 64 and 87 hours of rhenium remaining in heat treated molypdenite. Rhenium recovery is not particularly enhanced by the use of stabilizers. Both sodium persulfate and hydrogen peroxide are much more effective than hydrogen peroxide, and using only half the equivalent amount of active hydrogen, 83 to 8
Collect all Section 7.

Table l lH2O21-m- 2H2O217,6640,0092 3H2O2515,4870,00664H2O218
,2670,0091 5H2O257,4720,0070 6Na2S2081 9.0 84 0.004
87 Na2S2085 9.5 87 0.
00398 K2O219,2740,00799
H20□5 9.7 82 0.005910
H2So55 8.3 83 0.0048
Table■

Claims (1)

[Claims] (i) Gz) Crude molybdenum trioxide is suspended in an aqueous mineral acid, and (b) the slurry of step (α) is aged in the presence of an effective amount of an oxidizing agent to remove impurities from the crude molybdenum trioxide. leaching and then (C) separating the aged slurry from step (b) into solid purified molybdenum trioxide and an acid solution containing all the leached impurities. How to remove. (2) The method according to claim 1, wherein the oxidizing agent is selected from the group consisting of oxygen, hydrogen peroxide, monoperwL acid, and dipersulfuric acid. (3) The method according to claim 1 or 2, wherein the acid is sulfuric acid. (4) The method according to claim 3, wherein the sulfuric acid concentration is in the range of 0.5% to 35 sulfuric acid. (5) 450 as measured by silver-silver chloride and calomel electrodes
4. The method of claim 3, using sufficient oxidizing agent to maintain a potential between mV and 500 mV. (6) (c) Crude molybdenum trioxide is suspended in an aqueous solution containing 0.5% to 35% sulfuric acid; aging in the presence of an effective amount of an oxidizing agent selected from the group consisting of sulfuric acid to leach all impurities from the molybdenum trioxide; (c) purifying the slurry from step (b) of the solid molybdenum trioxide and leaching impurities; (d) to recover rhenium gold from the liquid partial force Δ from step (c); completely remove rhenium from crude molybdenum trioxide and recover the rhenium; (7) The method of claim 6, wherein the rhenium is recovered by step (C) mineral acid aqueous solvent extraction. (8) The rhenium is recovered from the ore from step (C). 7. The method according to claim 6, wherein the entire rhenium is recovered by completely dehydrating the acid aqueous solution and distilling the rhenium as total rhenium pentoxide.