JPS6222928B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for separating and recovering heavy metals in a solution. In particular, the present invention uses a polyalkylene polyamine type chelate resin to selectively recover heavy metals from solutions containing alkali metals or alkaline earth metals and heavy metals, or from solutions containing two or more types of heavy metals. It relates to a method for recovering each heavy metal with high purity. In recent years, with the progress of the electronic and nuclear industries, there has been a demand for higher purity of various metal materials.
On the other hand, since these high-purity metals are generally expensive, they are actively recycled and recovered. Currently, the common methods used to purify and recover these metals include coagulation-precipitation and solvent extraction, and both have the advantage of being suitable for mass production and having relatively low processing costs. There are problems with high purity and recovery rate. In response to this, ion exchange resin methods, particularly methods using chelate resins having chelate-forming groups, are promising. Among these, those with polyalkylene polyamine as a chelate-forming group have large chelate stability constants with various heavy metals, and the difference in chelate stability constants between heavy metals is also large, so they are suitable for separating and purifying heavy metals. In addition, since the polyalkylene polyamine does not form chelates with alkali metals and alkaline earth metals, heavy metals can be completely separated from these metals. Moreover, the heavy metals adsorbed on the resin can be desorbed with a solution containing acid or alkali, and this adsorption-desorption process can be repeated. Polyalkylene polyamine type chelate resin is
In general, it shows a large adsorption capacity for heavy metals in its free form, but in its acid-loaded form it either does not adsorb heavy metals at all, or even if it adsorbs them, its adsorption capacity is small.
However, since the polyalkylene polyamine type chelate resin is highly basic in its free form, when it is brought into contact with a solution containing a heavy metal, hydroxide may precipitate in the resin. Therefore, when passing a solution containing heavy metals through a polyalkylene polyamine type chelate resin column, if the resin is left in a free form to increase adsorption capacity, heavy metal hydroxides will be generated and the column will be clogged. Otherwise, the generated hydroxide precipitate may leak out inadvertently, worsening the separation of heavy metals from each other. In addition, the hydroxide precipitates formed in the pores of the resin are difficult to dissolve with a solution of acid or the like in an amount normally used for desorption of heavy metals, making it difficult to repeatedly use the resin. The reason why polyalkylene polyamine type chelate resins generate heavy metal hydroxides in free form is thought to be because some of the nitrogen atoms in polyalkylene polyamines become tertiary nitrogen for various reasons. . The present inventors investigated conditions for polyalkylene polyamine type chelate resins that have a large adsorption capacity and do not cause heavy metal hydroxide precipitation, and found that 5 to 90% of the nitrogen atoms in the functional groups are in the acid-loaded form. We have found that this purpose can be achieved by The present invention was achieved based on this knowledge, and its gist is that 5 to 90% of the nitrogen atoms in the functional group
A solution containing multiple metals including at least one heavy metal is passed through a resin tower filled with an acid-loaded polyalkylene polyamine chelate resin to selectively adsorb at least one heavy metal onto the resin. A method for separating and recovering heavy metals in a solution is characterized by repeating an adsorption step of adsorbing the heavy metals and a desorption step of passing an eluent through a resin tower adsorbing the heavy metals to desorb the adsorbed heavy metals. To explain the present invention in more detail, the polyalkylene polyamine type chelate resin used in the present invention includes a cross-linked copolymer having an aromatic ring, such as a cross-linked copolymer of styrene and dibylbenzene, and a cross-linked copolymer such as methyl chloromethyl ether. Resins obtained by reacting polyalkylene polyamines after halomethylation with polyalkylene polyamines, resins obtained by reacting polyalkylene polyamines with copolymers of ethyl acrylate and divinylbenzene, and polyalkylene polyamines with epihalohydrin or alkylene dibromide. There are resins having cross-linked bonds obtained by reaction. Heavy metals separated and recovered from the solution in the present invention include copper, iron, zinc, cadmium, vanadium,
Examples include molybdenum, nickel, cobalt, and silver. In particular, the present invention is applicable to nickel, cobalt, silver,
It is advantageous for separating and recovering molybdenum, vanadium, etc. with high purity. In the present invention, a solution containing the above-mentioned heavy metal is passed through a resin tower filled with a polyalkylene polyamine type chelate resin which has been partially acid-loaded in advance by a conventional method. The degree of acid loading of the resin is appropriately selected from the range of 5 to 90%. Generally, the greater the degree of acid loading, the lower the heavy metal adsorption capacity of the chelate resin, so it is preferable to reduce the acid loading rate as much as possible without producing heavy metal hydroxides. The acid to be loaded is appropriately selected from mineral acids such as sulfuric acid and hydrochloric acid, and organic acids such as acetic acid, depending on the heavy metal-containing solution to be passed. The invention can be carried out in various ways depending on the solution containing the heavy metal. When separating heavy metals coexisting in a solution containing alkali metals and alkaline earth metals from these metals, the heavy metals can be efficiently separated and recovered in a batch system using one resin tower. However, when separating and recovering each metal from a solution containing two or more types of heavy metals, two or more resin towers are used, and the flow of the solution between the resin towers is controlled by the composition of the effluent from the resin tower. It is preferable to recover each heavy metal with high purity by making various changes depending on the conditions.
For example, FIG. 1 shows an example of an apparatus in which two resin towers are used to recover each heavy metal with high purity from a solution containing two types of heavy metals. The opening and closing of the valve in the steady state in the device shown in the figure is as follows.

[Table] ×: Closed ○: Open Switching between each process is from the first step to the second step, and from the third step to the fourth step. When the concentration of
This is when the concentration of heavy metals with high selective adsorption properties in the tower effluent reaches the concentration in the original solution. Applying the operating principle of the device shown in Figure 1,
Apparatus consisting of three or more resin columns can be operated in a similar manner. Desorption of heavy metals from the resin column that has adsorbed heavy metals is carried out by a conventional method. Usually, a solution containing an acid is passed through to desorb heavy metals, and then the resin tower is washed with water, and then 10 to 95% of the nitrogen atoms in the functional groups of the resin are removed.
A solution containing an alkali equivalent to . The resin column is then blown with liquid or gas to mix the resin uniformly and to be used for the next heavy metal adsorption. In this way, the method of the present invention can be carried out using a minimum amount of acid and alkali. According to the method of the present invention, heavy metals can be easily separated and recovered from a solution containing heavy metals. Also,
A partially acid-loaded resin tower does not expand much even when a solution containing heavy metals is passed through it, so it is easy to pass the solution through it. In the present invention, the nitrogen atom content of the functional groups of the resin is measured by a conventional hydrochloric acid adsorption method. The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited to the following Examples unless it exceeds the gist thereof. Example 1 100 ml of free resin obtained by alkali treatment of the polyethylene polyamine type chelate resin Diaion CR-20 (Diaion is a registered trademark of Mitsubishi Chemical Industries, Ltd.) was placed in six beakers, and the functional groups of the resin were added to the beakers. Nitrogen atoms each 0, 20, 40, 60,
After adding 1N hydrochloric acid in an amount equivalent to 80% and 100% to achieve equilibrium, each column was packed into a column with an inner diameter of 15 mm to form a resin tower. Next, each resin tower was kept at 50℃, and Cu = 2000ppm, Ca = 2000ppm, Na ⁺ 2000ppm were added to it.
A metal chloride solution containing . The flow of liquid was stopped when the Cu value of the resin column effluent reached 1 ppm. After washing each resin column with demineralized water, 200 ml of 1N hydrochloric acid was passed through each resin column to elute the copper adsorbed on the resin column. Table 1 shows the adsorption amount of copper calculated from the amount of metal chloride solution passed through each resin column.

[Table] The purity of the recovered copper is at each hydrochloric acid loading rate.
Calcium and sodium were completely removed at over 99.8%. Regarding No. 2 to No. 6, the copper recovery rate calculated from the adsorption amount of copper calculated from the amount of liquid passed and the amount of copper desorption eluted by hydrochloric acid is approximately
However, the recovery rate of No. 1 with a hydrochloric acid loading rate of 0% was 92%, and the resin remained pale blue even after copper was eluted with hydrochloric acid. Example 2 In the same manner as in Example 1, 100 ml of free resin obtained by treating Diaon CR-20 with alkali was placed in eight beakers, and 0, 5, 15, and 30 ml of each of the nitrogen atoms in the functional groups of the resin were added to the beakers. , 45, 60, 75, and 90% of 1N sulfuric acid were added, and after equilibration, each column was packed with an inner diameter of 15 mm to form a resin tower. Then Ni = 1000ppm, Mg = 1000ppm, Ca =
A sulfate solution containing 500 ppm, Na ⁺ 1000 ppm, and NH ₄ ⁺ 500 ppm was passed at a space velocity (SV) of 2. The temperature of the resin column was maintained at 75°C. Ni in resin tower effluent
The flow of liquid was stopped when the amount reached 1 ppm. After washing each resin column with demineralized water, 200 ml of 1N sulfuric acid was passed through each column to elute the nickel adsorbed on the resin column. Table 2 shows the adsorption amount of nickel calculated from the amount of the treated liquid containing nickel passed through each resin tower.

[Table] The purity of the recovered nickel was 99.9% or higher for all Nos. 1 to 8. Further, the recovery rate of nickel was almost 100% for Nos. 2 to 8, but the recovery rate of nickel for No. 1 with a sulfuric acid loading rate of 0% was 96%. Example 3 130 ml of free resin obtained by alkali treatment of Diaion CR-20 was placed in two beakers, and 1N sulfuric acid was added in an amount equivalent to 20% of the nitrogen atoms in the functional groups of the resin to achieve equilibrium. . Next, each resin was packed into a column with an inner diameter of 20 mm to form two resin towers, which were connected as shown in FIG. Cu for this
A sulfate solution containing 1000 ppm of Ag and 2000 ppm of Ag was passed through the tube at a space velocity (SV) of 4. Switching from the first step or third step to the second step or fourth step was performed when Cu〓 leaked into the effluent from the first column or the second column. After washing the resin tower that had adsorbed Cu with demineralized water, 250 ml of 1N sulfuric acid was passed therethrough to remove Cu. The resin tower was then washed with demineralized water, and then 1N caustic soda was passed through it in an amount equivalent to 80% of the nitrogen atoms in the functional group, and the resin tower was washed with demineralized water.
After further mixing the resin uniformly, the mixture was again subjected to heavy metal adsorption. As a result, the amount of silver recovered per resin was 47.9 g and the amount of copper recovered was 24.0 g.
The purity of the recovered silver is 99.99%, and the purity of the copper is 99.99%.
The recovery rate was 99.9%, and the recovery rate was 100% in all cases. Example 4 After chloromethylating a copolymer of styrene and divinylbenzene, a chelate resin (amine content
6.7 meq/g - dry resin) was treated with an alkaline aqueous solution to make it into a free form, and then 130 ml of each was placed in two beakers, and 1N sulfuric acid was added thereto in an amount equivalent to 10% of the nitrogen atoms in the functional group to achieve equilibrium. I made it. This was packed into columns each having an inner diameter of 20 mm to form two resin towers, which were connected as shown in Figure 1. Ni to this
75 sulfate solution containing 1500ppm, Co〓2000ppm
℃, and nickel and cobalt were separated and recovered in the same manner as in Example 3. After the resin tower that had adsorbed Ni was desorbed with 1N sulfuric acid,
1N caustic soda was passed through the solution in an amount equivalent to 90% of the nitrogen atoms in the functional group, and used for the next adsorption of Ni. As a result, the amount of cobalt recovered per resin was 23.6 g, and the amount of nickel recovered was 23.5 g. The purity of the recovered cobalt is 99.99%, and the purity of nickel is 99.9%, with a recovery rate of 100%.
It was %.

[Brief explanation of the drawing]

FIG. 1 shows an example of an apparatus for carrying out the method of the present invention. 1 to 6: Valve, No. 1: First tower, No. 2: Second
Tower.

Claims (1)

[Scope of Claims] 1. A solution containing a plurality of metals including at least one heavy metal in a resin column filled with a polyalkylene polyamine type chelate resin in which 5 to 90% of the nitrogen atoms of the functional groups are acid-loaded. Repeating an adsorption step in which a liquid is passed through the resin to selectively adsorb at least one type of heavy metal onto the resin, and a desorption step in which an eluent is passed through a resin column that has adsorbed heavy metals to desorb the adsorbed heavy metals. A method for separating and recovering heavy metals in a solution. 2 Heavy metals are desorbed using an acid aqueous solution as an eluent, and after the heavy metals have been desorbed, an alkaline aqueous solution corresponding to 10 to 95% of the nitrogen atoms in the functional group is passed through the resin column, and then the resin in the column is uniformly mixed. 2. The method for separating and recovering heavy metals in a solution according to claim 1, wherein the solution is subjected to the next adsorption of heavy metals. 3. The method for separating and recovering heavy metals according to claim 1, which uses a resin in which 5 to 50% of the nitrogen atoms in the functional groups are acid-loaded. 4 A solution containing two or more types of heavy metals is passed through the resin tower to selectively adsorb at least one of the heavy metals onto the resin, and at the same time, a solution that contains the remaining heavy metals but hardly any of the heavy metals is passed through the resin tower. A method for separating and recovering heavy metals in a solution according to any one of claims 1 to 3, characterized in that the heavy metals are discharged from a solution. 5 An adsorption step in which a solution containing nickel and cobalt is passed through a resin tower to selectively adsorb nickel onto the resin, and at the same time a solution containing cobalt but almost no nickel is recovered; Claim 1, characterized in that the desorption step of passing an eluent through a resin column and recovering a solution containing nickel but hardly containing cobalt is repeated.
A method for separating and recovering heavy metals in a solution according to any one of items 1 to 3.