JPS5934135B2 - Molybdenum separation and concentration recovery method from molybdenum-containing aqueous solution - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for selectively separating, concentrating, and recovering molybdenum from an aqueous solution containing molybdenum.

Molybdenum is widely used as a component of special alloys, as a catalyst for removing sulfur from petroleum products, and as an extreme pressure improver for lubricating oils.

Recovery of molybdenum, a valuable metal, from these wastes is a very important issue from the viewpoint of resource conservation and resource reuse.

In general, molybdenum is recovered by dissolving the above substances in acid and then adsorbing and recovering them using activated carbon, by dissolving them in alkali and crystallizing them, or by extracting and separating them with an organic solvent after dissolving them (Kaimoto et al. , Published Patent No. 53-113792, 53-1
17602, 53-115603.53-11379
4) or adsorption recovery methods using ion exchange resins.

However, among the above methods, for example, the amount of adsorbed solution is small in the adsorption method using activated carbon, it is difficult to separate molybdenum with the alkaline crystallization separation method and the ion exchange method, and a mixture of other metals is recovered; Continuous operation is not possible with the extraction method, and it is difficult to say that any method is good.

The present inventor has been conducting research on the removal of harmful heavy metals and the recovery of valuable metals for some time, and has now invented an epoch-making method that makes it extremely easy to recover molybdenum from aqueous solutions.

The principle of the method of the present invention is extremely simple as follows.

That is, a substance containing molybdenum is decomposed by an appropriate means to form an aqueous solution.

After adjusting the hydrogen ion concentration of this aqueous solution to pH 0.5 to 5, it is passed through a column of granular or crushed activated carbon (hereinafter referred to as oxine carbon) adsorbed with 8-vitroxyquinoline (hereinafter referred to as oxine).

Molybdenum quantitatively forms oxine chelate and is adsorbed on activated carbon.

Then, the oxine activated carbon column was treated with sodium hydroxide,
Alternatively, molybdenum is removed by washing with an alkaline aqueous solution such as ammonia water and recovered as a sodium molybdate or ammonium aqueous solution.

Oxine charcoal columns can be used repeatedly after being washed with water.

The oxine activated carbon used here can be made by immersing activated carbon in a solution of oxine dissolved in an organic solvent such as ethyl alcohol or methyl alcohol and drying it, but it can also be made by directly mixing activated carbon and powdered oxine ( Motojima et al., published patent application No. 54-23093) is the simplest.

Note that if ordinary activated carbon is used, oxine adsorbs up to about 0.35% of its weight, but for the purpose of the present invention, it adsorbs up to 0.1 to
From an economic point of view, it is appropriate to adsorb 0.2 of the amount.

Molybdenum in an aqueous solution is very well adsorbed to oxine charcoal within the pH range of 0.5 to 5.

However, in a strongly acidic solution, desorption of adsorbed oxins is observed, so it is not very preferable to lower the pH to 0.8 or less.

On the other hand, if the pH is 1.5 or higher, the coexisting heavy metals will be adsorbed to the oxine charcoal and will hinder the adsorption of molybdenum, which is not suitable when heavy metals coexist.

For this reason, it is optimal to adjust the pH of the aqueous solution to O9&~1.3, and in this pH range, there is almost no adsorption of other heavy metal ions.

Molybdenum adsorbed on oxycharcoal can be quantitatively desorbed using an alkaline aqueous solution with a pH of 8 or higher.

In this case, if a dilute alkaline aqueous solution is used, a large amount of aqueous solution is required for quantitative desorption of molybdenum, which is not suitable for the purpose of concentrating molybdenum, and when a concentrated alkaline solution is used, it takes time to recover the molybdenum in the desorbed liquid. It becomes uneconomical.

Ultimately, it is appropriate to repeatedly use an alkaline aqueous solution or an ammonia aqueous solution of 0.5 to IN.

The optimum conditions for liquid passage during molybdenum adsorption vary depending on the particle shape of the activated carbon used, the adsorption amount of oxin, and the shape of the column used, but activated carbon with a particle size of 24 to 42 mesh adsorbs 1/10 of the amount of oxin. When a column with a height of 300 mm is made using oxidized oxine carbon, the linear velocity is 5.
It is possible to adsorb and collect molybdenum up to 1001n9 per gram of oxine coal by passing the liquid at a rate of 0.00 cm/hr.

Note that the adsorption rate at this time is more effective at a higher temperature than room temperature, and adsorption may be carried out at a temperature of 60 to 80°C.

It is possible to increase the flow rate of the through-liquid by 2 to 3 times that at room temperature.

The alkaline solution flow rate when desorbing molybdenum from oxine carbon is naturally preferably as low as possible in order to recover molybdenum quantitatively.
It is economical to use it 15 times.

Using IN sodium hydroxide or ammonia water,
Molybdenum can be desorbed at a linear flow rate of 1/20 of that during adsorption, and molybdenum can be quantitatively desorbed and recovered in an aqueous solution with an amount 4 to 5 times the amount of the oxine charcoal used.

By heating and concentrating this repeatedly used alkaline solution, sodium molybdate or ammonium crystals can be precipitated and separated, and the mother liquor is diluted to an appropriate amount and used again as a desorbed solution.

Needless to say, the same effect can be obtained even if an aqueous potassium hydroxide solution is used to remove molybdenum.

The present invention will be described in detail below with reference to Examples.

Example 1 Oxine charcoal was prepared by adsorbing 1/1O of oxine using 24 to 48 mesh crushed coconut shell activated carbon, and the oxine charcoal was placed in a glass tube with an inner diameter of 12.5 mm and a length of 200 mm.
A column was prepared by packing to a height of 00 mm.

An aqueous solution containing 100 ppl of molybdenum and having a pH of 1.0 was passed through the solution at a flow rate of 240 ml/hr, and the effluent was divided into 20 d portions using a fraction collector, and the breakthrough point was determined by atomic absorption spectroscopy of the molybdenum.

A schematic diagram of the experimental apparatus used in this case is shown in Fig. 1, and a breakthrough curve is shown in Fig. 2A.

As is clear from A in Figure 2, no molybdenum was observed in the effluent up to 4.11, and no molybdenum was observed in this oxine carbon column.
The number indicates that 500η of molybdenum was collected.

Next, IN sodium hydroxide aqueous solution was added to this column at a flow rate of 0.
．． The adsorbed molybdenum was desorbed by flowing at a rate of 5 ml/m, and the molybdenum contained in each 5M effluent was quantified. The results are shown in FIG.

It can be seen that most of the molybdenum is desorbed in the outflow water up to 25 m1.

After washing the column with water, the aqueous molybdenum solution was passed through it again under the same conditions as at the beginning, and the breakthrough curve was determined, and the results are shown in FIG. 2B.

Although there is a slight decrease in performance, they show almost the same adsorption performance.

Figure 2 shows the breakthrough curve when this operation is repeated five more times.
As shown in C, it is clear from the results of this experiment that oxine charcoal can be repeatedly used for adsorption and desorption of molybdenum.

Example 2 A column with a diameter of 50 mm and a height of 300 mm was made using oxine charcoal that had oxine charcoal adsorbed with 15/100 of its weight of oxine using 8 to 32 mesh crushed coconut shell activated carbon and packed to a height of 200 mm. 50 pI on the oxine charcoal column
) fit aqueous solution containing molybdenum at pH 0.8 360
1 at a flow rate of 121/hr.

Thereafter, the molybdenum adsorbed on this column was desorbed using 2.51 IN ammonia water at a flow rate of 0.51/hr.

The molybdenum concentration in the recovered liquid is 6.7~/rnl, approximately 13
This meant that the concentration was 0 times, and the recovery rate was 93%.

[Brief explanation of drawings]

Explanation of FIG. 1, schematic diagram of the experimental equipment used in Example 1, ■Processing liquid bottle, ■Processing liquid stock solution, ■Meteritizing pump, ■Glass column, ■Oxine charcoal, ■Stopcock, ■Fraction collector. Description of FIG. 2, performance curve of oxine charcoal in repeated use of oxine charcoal-packed column, explanation of FIG. 3, graph of recovery amount of molybdenum adsorbed on oxine charcoal.

Claims (1)

[Claims] 1. By bringing a molybdenum-containing aqueous solution into contact with activated carbon adsorbed with 8-hydroxyquinoline in a weakly acidic state, molybdenum in the aqueous solution is selectively adsorbed onto the activated carbon and concentrated, and then the activated carbon is washed with an alkaline aqueous solution. A method for separating, concentrating and recovering molybdenum from a molybdenum-containing aqueous solution, which is characterized by transferring molybdenum to an aqueous layer and recovering molybdenum.