KR960010812B1 - Recovering method of cobalt - Google Patents

Abstract

The recovering method of cobalt comprises washing byproducts(slurry) of malonic acid ester process with oil to remove organic impurities; extracting cobalt in slurry with an organic solvent such as D2EHPA, (2-hydroxy-5-nonyl-acetophenone) oxime type and 8-hydroxy quinone; concentrating them, and washing the extracted cobalt liquid with water and recovering the concentrated cobalt by extracting inversely the washed cobalt liquid with an acid at 30-60deg.C. Cobalt oxide is recovered by neutralizing the liquid containing cobalt with alkali and calcining for 2-4hrs. at 300-400deg.C and then recovering cobalt oxide.

Description

A method for recovering cobalt from the thick liquid generated in the malonic ester production process.

1 is a recovery process diagram of cobalt using solvent extraction according to a preferred embodiment of the present invention,

2 is the cobalt extraction equilibrium in D2EHPA solvent.

The present invention relates to a method for recovering cobalt from the rear liquor generated in the malonic acid ester production process, in particular, by employing a solvent extraction method that can solve the large-capacity, purity and economical problems of the cobalt recovery device to obtain high-purity cobalt lactate or cobalt oxide It relates to a method of recovery.

In the preparation of malonic acid ester (octacabonyldicobalt) is used as a catalyst, this octacarbonyl dicobalt is usually prepared by reacting cobalt oxide hydrogenated carbon monoxide under high temperature and high pressure.

Cobalt salt solution generated after the purification of the malonic acid ester (hereinafter referred to as a later solution) is generated about 10 tons / day and as shown in Table 1 malonic acid, isopropyl alcohol, malonate (malonate: malonic acid) Derivatives), toluene and the like as cobalt, nickel, iron, salt, forget-me-not (Na ₂ SO ₄ ), sulfuric acid, etc., cause severe pollution if not treated properly.

Table 1 shows the approximate concentrations of organic and inorganic substances contained in the rear liquor.

In addition, this thick liquor has a low cobalt content, for example, 1-10 gr / liter, and has a large amount of salt and organic matter. Therefore, a general separation technique requires a large recovery device and is not economical because high-purity cobalt cannot be recovered. .

General conventional recovery methods and problems for them are as follows.

A. Solution Incineration

In this method, a residue is obtained in a high temperature flame and the residue is washed to recover cobalt oxide. However, this method has a problem in that the purity of the cobalt oxide is lowered because the solution organic matter is not burned due to the low content of the organic matter, and thus, a large amount of energy is consumed when spraying into the flame, and the residue is not selectively separated.

B. Neutralization

This method is a method of obtaining cobalt hydroxide by neutralizing with alkali, because impurity such as iron and a large amount of organic industry are mixed, and there is a problem that the purity of cobalt oxide obtained is low.

B. Neutralization

This method is a method of obtaining cobalt hydroxide by neutralizing with alkali, and has a problem in that the purity of cobalt oxide obtained is low because impurities such as iron and a large amount of organic salts are mixed.

C. Ion Exchange

This method is a method of recovering cobalt by ion exchange. Cobalt salt solution has a large amount of Na ions and sulfuric acid, which is inefficient in ion exchange and requires a large capacity ion exchanger.

E. Methods of Using Hydrogen Emulsified or Sodium Sulfate

This method is a method of recovering cobalt emulsion by using hydrogen sulfide or sodium sulfide. This recovery process is not suitable because there is a bad odor pollutant.

F. High Pressure Hydrogen Reduction

This method is a method of recovering cobalt metal under high pressure hydrogen pressure and requires a high pressure water tank to treat 10 tons / day, which is a risk of hydrogen explosion and uneconomical.

G. Electrowinning

This method requires a large capacity electrolyzer and is uneconomical when considering electricity bills.

As described above, the conventional cobalt recovery method has at least one problem such as a large capacity of the recovery device, purity, economical efficiency, pollution, etc.

Accordingly, it is an object of the present invention to provide a method for recovering cobalt from the rear liquor generated in the malonate ester manufacturing process, which can solve the problem of large capacity, purity, economy and pollution of the recovery apparatus.

In order to achieve the above object, according to the present invention, a process for removing organic impurities by washing with a petroleum the dissolved liquid of the sediment or the sediment generated in the malonic ester production process, and in the liquid after the organic impurities are removed Cobalt is extracted and concentrated by an organic solvent extraction method, and cobalt extracted and concentrated in the organic solvent is washed with water and back extracted with acid to obtain concentrated cobalt or neutralizing the back extraction solvent with alkali to recover the cobalt oxide after firing. Provided is a method for recovering cobalt from a thick liquor generated during the production of malonic esters, comprising the step of:

In addition, in the above method according to the present invention, it is preferable to further include a step of neutralizing the thick liquid prior to the step of removing the organic impurities.

The extraction concentration is carried out in the extraction tank consisting of the first to fourth cells, the rear liquid is sequentially transferred from the first cell to the fourth cell, the organic solvent is sequentially transferred from the fourth cell to the first cell by the organic solvent The cobalt ions are allowed to be extracted and the extracted concentrated quabalt is obtained from the first cell. Thereafter, the extracted concentrated cobalt is washed with 1-3pH of water and introduced into the fourth process, and the cobalt extracted liquid is transferred to the organic wastewater treatment process.

In addition, the concentrated cobalt extracted through the cobalt recovery process after the washing process is transferred to the rear stage through the front stage of the two stage back extraction tank, and the acid is transferred to the front stage through the rear stage to obtain a back extraction solution from the front stage. The temperature at this time is maintained at 30-60 ℃.

The resulting back extraction solution is then concentrated to give a cobalt salt, or neutralized with alkali and calcined to obtain cobalt oxide.

Organic solvents added to the above extraction and concentration process include D2EHPA (di- (2-ethylhexyl) phosphate), 2-hydroxy-5-nonyl-acetophenone oxime (Lix64N, Lix84), 2-ethyl Hexyl Hydrogen 3-Ethyl Nucleic Acid Phosphoric Acid (PC-88A-SME418), Carboxylic Acid (Versatic acid, Naphthenic Acid), Phosphic Acid (Cyanex 301,302,272), 8-hydroxyquinoline (8 -hydroxyquinoline series (Kelex 100,120) and the like can be used, and also a mixture of these organic solvents can be used.

The general chemical reaction of the transition metal and organic solvent is as follows.

M ⁿ + n (HO) → M (−O) + nH ⁺

Where M is a transition metal and O is an organic solvent.

In addition, the acid that can be used for back extraction in the cobalt recovery process is sulfuric acid, nitric acid, hydrochloric acid and the like.

The cobalt sulfate is extracted from D2EHPA as follows.

2 (RO) ₂ PO (OH) + CoSO ₄ → (RO) ₂ PO (O-Co-O) OP (RO) ₂ + H ₂ SO ₄

If the amount of cobalt thick liquid is generated a lot, the logistics transfer cost is high, the cobalt thick liquid may be solidified in the form of a sediment to reduce its volume, and may be recovered during the treatment to recover cobalt by the aforementioned method.

Hereinafter, the present invention will be described in detail with reference to FIG. 1.

1 is a process flow diagram of cobalt recovery using solvent extraction according to a preferred embodiment of the present invention.

Referring to FIG. 1, first, since the rear liquor generated in the malonsa ester refining process has a high acidity, one of alkalis, for example, NaOH, Na ₂ CO ₃ , Ca (OH) ₂ , CaO, NH ₄ OH, may be used. Set to pH = 2.

Thereafter, hydrogen peroxide (H ₂ O ₂ ) is added to oxidize the ferric iron to trivalent iron, and then alkali is added again to precipitate and remove iron with iron hydroxide (Fe (OH) ₃ ) at pH = 3.0-3.5.

It should be noted that iron must be removed in advance, as iron causes fatal detoxification to organic solvents in subsequent processes.

Since iron is removed after the liquid contains a large amount of organic matter, in the separate solvent extraction stage (first cell (C1)) to prevent contamination of the organic solvent introduced into the rear stage, using a petroleum and the like washing step Go through.

The washed liquor is then subjected to a solvent extraction process at pH = 2-6.5.

This solvent extraction process requires about three to eight steps of cells, but in the present invention shown in FIG. 1, cobalt extracted and concentrated by an extraction tank composed of second to fifth cells (C2 to C5) is obtained.

The washed liquid is added to the second cell (C2) and sequentially transferred to the fifth cell (C5), on the contrary, for example, the organic solvent, for example, D2EHPA is added to the fifth cell (C5) and then sequentially to the second cell (C2). ) So that cobalt ions are extracted by the organic solvent. At this time, in order to maintain pH = 4, Na ₂ CO ₃ , NaOH, NH ₄ OH solution, etc. are injected into the micropump.

The extracted concentrated cobalt is obtained from the second cell (C2) and transferred to the sixth cell (C6) which is washed with water of pH = 1-3 to prevent the incorporation of impurities, and the cobalt is removed from the fifth cell (C5). The extracted liquor is sent to an organic wastewater treatment process.

The concentrated cobalt extracted in the sixth cell C6 is then supplied to a back extraction tank consisting of two stage cells. The cobalt extracted and concentrated first is introduced into the seventh cell C7, which is the front end, and transferred to the eighth cell C8, which is the rear end. On the contrary, the acid, for example, H ₂ SO _4, is introduced into the eighth cell C8. The back extract is obtained from the seventh cell C7 by being transferred to the seventh cell C7.

The variable of the back extraction process may be a temperature, and when the temperature is low, the time of back extraction takes a very long time, and in the case of 60 ° C. or more, the solvent is melted and energy is excessively consumed, so the range of 30 ° C. to 60 ° C. is preferable. .

In addition, nitric acid, hydrochloric acid, and the like may be used as the acid used for the reverse extraction.

Thereafter, the back extract is periodically collected and concentrated to obtain a cobalt salt or neutralized with alkali and calcined to obtain cobalt oxide. At this time, the extracted cobalt has a purity of 99.9% or more.

Meanwhile, the organic solvent that has undergone back extraction is transferred from the eighth cell (C8) to the ninth cell (C9) constituting the washing stage for removing the strong acid, and the sixth cell (C6) constituting the washing stage again after the first washing. Circulating door is processed.

Example 1

First, looking at the composition of the waste liquid generated in the malonic ester production process is shown in Table 2 below.

25 liters of a strongly acidic thick liquid having a composition as shown in Table 2 was collected, neutralized to pH level with 189 g of Ca (OH), and 100 ml of HO was added to 25 liters of the thick liquid to oxidize the bivalent impurity iron to trivalent iron. The divalent impurities are then sedimented at pH 3.5 with alkali in the same manner as above.

Then, D2EHPA was used as a solvent and experimented with D2EHPA 15% V / V, petroleum 75% V / V, and isodecanol 10% V / V. The saturated cobalt extraction amount of this solvent is 12 g and the brief process of solvent extraction is shown in FIG.

The equilibrium extraction curve is shown in FIG. 2 when tested at pH = 4 and a temperature of 20 ° C. using this solution containing 4.9 g / ι cobalt. At this time, as a pretreatment step, the rear liquid was washed with petroleum to prevent incorporation of organic impurities into the solvent (first cell). Extraction stage in 4 stages (2nd to 5th cell), washing between extraction stage and back extraction in 1 stage (6th cell), back extraction in 2 stages (7th and 8th cell), final washing Was composed of one stage (ninth cell), respectively.

When the liquid flow rate is 70ml / min, 35ml / min in the solvent phase NaCO of 1 mol concentration was injected to adjust the cobalt concentration at the extraction stage and pH = 4.0 at each stage and the flow rate is shown in Table 3 below.

Prior to back extraction, the pH of the ninth cell was pH = 1.7, followed by the first stage of washing (sixth cell), followed by two stages of back extraction with 2 molar sulfuric acid solution. The temperature of the back extraction process was set to 40 ° C. and back extraction was performed until the acidity of the sulfuric acid solution became pH = 1.

1000 ml of the solution obtained by the back extraction was collected and concentrated to 500 ml to obtain 317 g of cobalt lactate (CoSo, 7HO). 660 ml of distilled water and 110.6 g of concentrated sulfuric acid were added to the crystallized liquid, and the mixture was circulated in a back extraction process. Thereafter, 1000 ml of back extract was collected every 3 hours and 20 minutes to recover cobalt lactate in the same manner.

In order to obtain cobalt oxide from the back extraction solution, NaCO284g was added to a back extraction solution of pH = 1 to obtain 242g of cobalt hydroxide, and calcined at 350 ° C for 3 hours to obtain 149g of cobalt oxide.

All conditions and processes were maintained in the same manner as in Example 1, and high-purity cobalt sulfate of 99.9% or more was obtained by using 2-ethylnucleosil hydrogen 2-ethylnucleic phosphate (PC 88A) instead of D2EHPA in the use of the organic solvent.

Example 2

All conditions and processes were maintained in the same manner as in Example 1, and high-purity cobalt sulfate of 99.9% or more was obtained by using 2-ethylnucleosil hydrogen 2-ethylnuclear phosphate (PC 88A) instead of D2EHPA in the use of an organic solvent.

Example 3

Cobalt was extracted in a batch type rather than in a continuous process using an organic solvent prepared in the same manner as the cobalt thick liquid (the following aqueous solution) as in Example 1. 300 ml of the aqueous solution and 300 ml of the prepared organic solvent were placed on a separatory funnel, adjusted to pH = 4, shaken vigorously for 2 minutes, and left for 5 minutes to separate the organic solvent phase and the aqueous phase from the difference in specific gravity. At this time, the cobalt in the aqueous phase is transferred to the organic solvent phase. 300 ml, 2 mole sulfuric acid solution (hereinafter, referred to as back extract) was added to the temperature of 40 ° C., shaken for 2 minutes, left for 5 minutes, and then separated from the back extract. It should be noted that each step should be washed thoroughly with distilled water to remove impurities and residual sulfuric acid. When this method is carried out four times with respect to the first aqueous solution, the red aqueous solution becomes clear and the residual cobalt concentration is 3 ppm or less. The back extract is repeated until the pH = 1 to concentrate the cobalt. High purity cobalt sulfate more than 99.9% was obtained from the concentrated back extract.

As described above, according to the present invention, there is provided a cobalt recovery method that can solve the pollution problem together with the problem of the purity, economical efficiency and large capacity of the recovered cobalt.

Claims (4)

The process of removing organic impurities by washing with petroleum the solution of the latex or the precipitate generated in the malonic ester manufacturing process, and extracting the cobalt in the after removing the organic impurities at pH 2-5 organic solvent extraction method The extraction and concentration process by and the cobalt extracted and concentrated in the organic solvent washed with water and back extracted with acid at a temperature of 30-60 ℃ to obtain a concentrated cobalt or by neutralizing the back extraction solution with alkali temperature of 300-400 ℃ Method for recovering cobalt from the thick liquid generated during the production of malonic acid ester, characterized in that it comprises a step of recovering with cobalt oxide after firing at 2-4 hours. The organic solvent according to claim 1, wherein the organic solvent is D2EHPA (2-hydroxy-5-nonyl-acetophenone) oxime system, 2-ethylhexyl hydrogen 2-ethylnuclear phosphoric acid, carboxylic acid system, phosphinic acid system, and 8 The cobalt is recovered from the rear liquid generated during the preparation of malonic acid, characterized in that any one of the hydroxyquinoline system or any mixture thereof, and the acid used for the back extraction is any one of sulfuric acid, nitric acid and hydrochloric acid. How to. The method of claim 1, wherein the extraction and concentration process is to recover the cobalt from the rear liquor during the production of malonic esters, characterized in that to transfer the cobalt ions to the organic solvent using a batch type (batch type). The method of claim 1, further comprising neutralizing the rear liquor prior to the removal of the organic impurities, wherein the cobalt is recovered from the rear liquor generated during malonic acid ester production.