JP3355362B2 - Method for leaching valuable metals from spent catalyst - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a leaching method for recovering valuable metals from spent catalyst used for desulfurization and hydrogenation of heavy oil.

[0002]

2. Description of the Related Art Catalysts made of one or a combination of molybdenum, nickel, cobalt and the like are widely used as desulfurization catalysts and hydrogenation catalysts for heavy oil, as well as catalyst carriers made of alumina, silica or the like. . This type of catalyst is discarded as a waste catalyst because its performance deteriorates after a certain period of use.However, in addition to the above-mentioned metals, metals contained in heavy oil such as vanadium, nickel and iron adhere to this waste catalyst. Therefore, attempts to recover valuable metals from these spent catalysts have been made for a long time, and many recovery methods have been proposed. However, all of the conventional recovery methods have advantages and disadvantages, and in fact, they cannot be said to be sufficiently satisfactory. For example, to make vanadium and molybdenum highly reactive oxides, 500 to 7
There is a method of oxidizing and roasting at a high temperature of 00 ° C. However, in this method, the oil in the spent catalyst burns, causing a local rise in temperature. There is a problem that it will not be dissolved with an acid or the like. There is also a method in which vanadium or molybdenum is subjected to soda roasting and then alkali extraction. However, nickel or cobalt becomes a solid solution with alumina as a catalyst carrier and becomes insoluble in water, so that nickel or the like cannot be recovered. There is.

As a method for improving the above-mentioned conventional method, there is a method in which an oxidized roast is directly leached with an acid (for example, Japanese Patent Publication No. 1-25322), but this method requires a large amount of an expensive reducing agent. Therefore, the recovery cost tends to be high, and when molybdenum, vanadium, nickel, and cobalt are separated from the leached liquid, impurities such as aluminum, iron, and phosphorus are leached in large amounts, and the processing becomes complicated. There are problems that the purity of the recovered metal is deteriorated and the yield is reduced.

[0004]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a leaching method which does not require a large amount of an expensive reducing agent and can recover valuable metals with high purity and in good yield. .

[0005]

In order to solve the above problems, the present invention employs the following configuration. That is, the method for leaching valuable metals from spent catalysts according to the present invention comprises the use of 300 to 40 waste catalysts containing at least one of vanadium and molybdenum and at least one of nickel and cobalt.
After heating at 0 ° C. to remove oil, 350-4
Oxidation and roasting at a temperature of 50 ° C.
Alkaline leaching in an alkaline solution of 10 to 12 yields a leaching solution containing at least one of molybdenum and vanadium, and the insoluble residue is acid leached in an acidic solution of pH 1 to 3 and filtered to remove nickel, cobalt Characterized in that a leachate containing at least one of the following is obtained. Hereinafter, a detailed example will be described with reference to specific examples.

[0006] The waste catalyst as a raw material is a desulfurization catalyst for heavy oil, a hydrogenation catalyst, or the like. For example, it contains valuable metals such as molybdenum, nickel, and cobalt, and uses alumina or the like as a carrier. This type of waste catalyst often contains iron, arsenic, and the like coming from petroleum.
The spent catalyst is removed by using, for example, a rotary kiln for 300 minutes.
Heat to ~ 400 ° C and deoil. The residence time of the rotary kiln in the heating zone may be about 30 minutes. During this time, the spent catalyst is exposed to a gas atmosphere containing oil, moisture and the like generated from the spent catalyst itself. If the temperature of the continuous deoiling process is less than 300 ° C., the deoiling is not sufficiently performed,
If the temperature is higher than 00 ° C., part of the oil is decomposed and adheres to the surface of the catalyst as tar-like carbon.

[0007] After the deoiling step, the spent catalyst is subjected to an oxidation roasting treatment of heating to 350 to 450 ° C in an air atmosphere. This treatment removes sulfur (S), carbon (C), etc., molybdenum to MoO ₃ , and vanadium to V ₂ O
Oxidized to ₅ . In this case, a small amount of a lower oxide may be present. If the temperature of this treatment is lower than 300 ° C., the progress of oxidation becomes extremely slow, which is not preferable. At a high temperature, vanadium, nickel, cobalt and the like easily form a compound with alumina (Al ₂ O ₃ ), and when the temperature is higher than 450 ° C., the tendency becomes remarkable. The formation of such a compound is not preferred because the leaching rate in the subsequent leaching step is reduced.

The roasted product obtained by the above treatment is subjected to alkaline leaching in an aqueous alkaline solution. Examples of the alkali include caustic soda (NaOH) and sodium carbonate (N
a ₂ CO ₃ ) or the like is used. The pH value of the alkaline aqueous solution is preferably 10 to 12, and the temperature of the solution is 50 ° C.
It is preferable to make the above. In order to completely oxidize the trace amount of lower oxide remaining in the spent catalyst, it is preferable to add a small amount of an oxidizing agent, for example, hydrogen peroxide to this aqueous alkali solution. By this alkali leaching, molybdenum dissolves as sodium molybdate and vanadium dissolves as sodium vanadate. This liquid is filtered, and the filtrate is treated by a known wet treatment to recover molybdenum and vanadium.

On the other hand, the residue after the filtration is subjected to acid leaching,
Recover nickel, cobalt, etc. This acid leaching is performed using a suitable acid such as sulfuric acid, nitric acid, hydrochloric acid and the like. The pH value of this acidic solution is preferably from 1 to 3,
More preferably, it is set to 5 to 2. This acid leaching elutes nickel, cobalt and the like in the form of, for example, nickel sulfate, cobalt sulfate and the like. This solution is filtered, and metals such as nickel and cobalt are recovered by a known wet treatment.

[0010]

Embodiments of the present invention will be described below. 1 kg of spent catalyst having the chemical components shown in Table 1 was added to a rotary catalyst.
Using a kiln-type continuous furnace, deoiling was performed at a raw material temperature of 350 ° C. The weight after deoiling was 820 g. 820 g of this spent catalyst was fed to an oxidation roasting furnace at a raw material temperature of 350 to 40.
Roasted at 0 ° C for 10 hours. The weight of the product after the roasting was 715 g, and its chemical components were as shown in Table 1.

[0011]

[Table 1]

500 g of the above oxidized roasted product was leached with 1.5 liters of hot water (70 ° C.) at pH 11 for 1 hour with caustic soda. The alkaline solution contains 35
80% aqueous hydrogen peroxide was added. The leached liquid was filtered with a reduced pressure filter to obtain a leached liquid for recovering molybdenum and vanadium. The residue was washed with 1 liter of warm water, and sulfuric acid was added with 1 liter of warm water to adjust the pH to 1 at pH 2.0.
After leaching for a time, the solution was filtered with a vacuum filter to obtain a leaching solution for recovering nickel and cobalt. The residue at this time was washed with 1 liter of warm water and dried at 110 ° C. for one day and night with a drier, and weighed 288 g. The results of chemical analysis are shown in Table 2.

[0013]

[Table 2]

Molybdenum and vanadium are recovered from the leach liquor after the alkali leaching by performing a known wet treatment, and nickel and cobalt are similarly recovered from the leach liquor after the acid leaching by a known wet treatment. I was able to. The leaching rate of the valuable metal was as shown in Table 3.

[0015]

[Table 3]

[0016]

As is apparent from the above description, according to the leaching method of the present invention, valuable metals such as molybdenum, vanadium, nickel, and cobalt can be recovered in high yield from the spent catalyst obtained in the petroleum refining process. Leaching is possible, and by using this method, these valuable metals can be economically separated and recovered with high purity.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-54-60211 (JP, A) JP-A-51-86002 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C22B 1/00-61/00

Claims (1)

(57) [Claims] 1. A vanadium, 1 or more kinds of molybdenum
Above, and a spent catalyst containing at least one of nickel and cobalt is heated at 300 to 400 ° C. to remove oil, and then oxidized and roasted at 350 to 450 ° C. in air.
The obtained roasted product is alkaline leached in an alkaline solution having a pH of 10 to 12 to obtain one of molybdenum and vanadium.
A leachate containing the above is obtained, and the insoluble residue is pH 1
3. A method for leaching valuable metals from a spent catalyst, characterized by obtaining an leaching solution containing at least one of nickel and cobalt by acid leaching in an acidic solution of (1) to (3).