CA2265068C - Method for removal of lead ion - Google Patents
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- CA2265068C CA2265068C CA002265068A CA2265068A CA2265068C CA 2265068 C CA2265068 C CA 2265068C CA 002265068 A CA002265068 A CA 002265068A CA 2265068 A CA2265068 A CA 2265068A CA 2265068 C CA2265068 C CA 2265068C
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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Abstract
The invention is to provide a method for removal of a lead ion in that a lead ion is effectively removed from an aqueous solution, such as a nickel chloride solution, containing a lead ion to a low concentration, and an organic solvent can be regenerated in an economical and effective manner, and it relates to a method for removal of a lead ion comprising a step of contacting, at least once, an aqueous solution containing a lead ion with an organic solvent having a thiophosphinic acid structure, to extract and remove the lead ion, and a method for removal of a lead ion from a nickel chloride solution comprising (a) a first step of contacting, at least once, a nickel chloride solution containing a lead ion with an organic solvent having a thiophosphinic acid structure, to extract and remove the lead ion; (b) a second step of contacting the organic solvent subjected to extraction of the lead ion with an acidic solution having a pH value lower than that on the extraction and removal of the lead ion and in a range of from 0.5 to 3.0, to put back a valuable metal having been extracted along with the lead ion to the nickel chloride solution; and (c) a third step of subjecting the lead ion contained in the extractant to stripping as lead sulfate by using a sulfuric acid solution, and separating the lead sulfate to regenerate the extractant.
Description
METHOD FOR REMOVAL OF LEAD ION
BACKGROUND OF THE INVENTION
1. Field of the Invention:
The present invention relates to a method for removal of a lead ion from an aqueous solution, such as a nickel chloride solution, containing a lead ion in an efficient manner.
BACKGROUND OF THE INVENTION
1. Field of the Invention:
The present invention relates to a method for removal of a lead ion from an aqueous solution, such as a nickel chloride solution, containing a lead ion in an efficient manner.
2. Description of the Prior Art:
Raw materials of non-iron metals contain various impurities, and the methods are evaluated on the standard as to whether or not the impurities can be effectively removed.
Such a method is often employed for recovering a non-iron metal that a raw material is dissolved in an acid or an alkali to obtain an aqueous solution containing the objective element and impurities, and then the impurities are respectively removed by an operation, such as neutralization and sulfurization, to obtain a solution containing only the objective element to be recovered. Among the impurities, lead is considered as an element that often should be removed since its content is relatively large.
Lead is generally present in the form of a PbZ+ ion in an aqueous solution. The removal of such a leached lead ion is often conducted by utilizing the small solubility of PbSO4 and PbS. Such methods are practiced in that S2- ion or an SO42" ion is added to the resulting leached solution to form a compound having a small solubility by combination with a lead ion, or in alternative, a lead ion is oxidized from divalent to tetravalent by oxidizing a solution containing the lead ion, and Pb02 thus formed having a small solubility is removed.
For example, in the case where nickel is produced by using nickel matte, the nickel matte is dissolved by chlorine, hydrochloric acid or sulfuric acid. Impurities contained in the resulting solution, such as lead, iron and copper, are then respectively removed, and a pure nickel solution thus obtained is subjected to electrolysis to obtain metallic nickel.
In order to produce metallic nickel having a high purity, the impurities such as lead must be removed to a low concentration before the electrolysis, and particularly, metals, such as lead and copper, having a smaller ionization tendency than nickel are desirably removed to a sufficiently low concentration before the electrolysis.
In the method in which lead is removed in the form of PbSO4, the solubility of these compounds are not sufficiently low, and a lead ion remains in the solution, so that nickel having a high purity is difficult to be produced.
Another method has been proposed, in which lead is removed in the form of a sulfide by adding hydrogen sulfide or sodium sulfide. This method is based on the fact that a sulfide of lead has a higher stability than nickel. However, this method involves problems in operation, in that a toxic gas such as hydrogen sulfide is used, and because a precipitate of NiS is liable to gradually formed due to a slight amount of a hydrogen sulfide gas dissolved in water even after completion of the reaction, the hydrogen sulfide gas must be removed from the solution by deaeration.
Still another method has been proposed, in which lead is removed as a metal by cementation by adding metallic iron or nickel. In this method, lead is subjected to cementation since lead has a smaller ionization tendency than nickel, but cannot be removed effectively because the difference in potential from nickel is small.
Still another method has been proposed, in which lead is removed by oxidation of the solution by using Cl2 gas. In this method, lead is removed in the form of Pb02 having a small solubility by oxidizing the lead ion from divalent to tetravalent. However, since a strong oxidizing agent such as C1Z is used, nickel contained in the solution is also oxidized to form Ni(OH)3, which brings about excessive use of the oxidizing agent. In the chloride solution, since a lead ion forms a complex ion with chlorine to be present in the form of PbC13- and PbC142-, removal of the impurities becomes difficult, and particularly, removal of a lead ion to a low concentration is extremely difficult.
Separation and removal of various metallic ions by using the solvent extraction technique or the ion exchange resin technique is recently practiced, which is also applied to removal of a lead ion. In the adsorption method by an ion exchange resin, for example, removal of a lead ion from a sulfuric acid solution by using a cation exchange resin, and that from a chloride solution by using an anion exchange resin are practiced. However, the adsorption removal using the ion exchange resin is not practical because the adsorption amount of the resin is small, and thus the adsorption and desorption operation should be frequently repeated.
In the method using the solvent extraction technique, there is a report of the use of an acidic extractant. However, in the case where lead is removed from a solution containing nickel and cobalt, since the extractability of these metallic ions is close to that of a lead ion, effective removal of a lead ion is diff icult .
Even when only lead can be selectively extracted, it is not practical because of the following reasons.
The solvent extraction is constituted by three major steps, i.e., extraction, washing and stripping, and lead thus extracted is subjected to the stripping by using a mineral acid, to regenerate an organic solvent.
Hydrochloric acid is frequently used in the stripping from the standpoint of prevention of deterioration of the organic solvent and handling, and a lead chloride solution is obtained as a strip liquor. However, because the solubility of lead chloride is as small as about from 0.9 to 1.6 g/L in 1N to 3N
hydrochloric acid solution, which is used in the stripping, at ordinary temperature, crystals of lead chloride are liable to be deposited, and deposition of the crystals in the equipment and piping may bring about troubles.
In order to operate stably, the lead concentration in the strip liquor should be controlled not to exceed the solubility of lead chloride, and as a result, the stripping should be conducted by using a large amount of an acid solution.
Accordingly, even a strip liquor exhibiting sufficient stripping performance as an acid concentration should be withdrawn from the stripping system to prevent deposition of crystals of lead chloride, and the same amount of a new hydrochloric acid solution should be added. The strip liquor thus withdrawn is generally subjected to a neutralization treatment, and thus the strip liquor having a high acid concentration is disadvantageous since it requires a large amount of a neutralizing agent.
Therefore, even in the case of the organic solvents that can extract lead, a method for removal of a lead ion by using these solvents involves various problems, and there is a difficulty in practical operation.
As described in the foregoing, there has been no method for removal of a lead ion from a nickel chloride solution containing a lead ion in an efficient manner, and development of a method for removal that can be practically conducted has been demanded.
According to the conventional methods, a lead ion cannot be completely removed from a solution containing a lead ion.
SUMMARY OF THE INVENTION
An object of the invention is to solve the problems described above, and to provide a method for removal of a lead ion in that a lead ion is effectively removed from an aqueous solution, such as a nickel chloride solution, containing a lead ion to a low concentration, and an organic solvent can be regenerated in an economical and effective manner.
As a result of extensive investigations made by the inventors to attain the objects described above, it has been found that when an aqueous solution, such as nickel chloride solution, containing a lead ion is made in contact with an organic solvent phase having a thiophosphinic acid structure, a lead ion can be effectively removed. Thus, the invention has been completed.
The invention relates to, as a first embodiment, a method for removal of a lead ion comprising a step of contacting, at least once, an aqueous solution containing a lead ion with an organic solvent having a thiophosphinic acid structure, to extract and remove the lead ion. The aqueous solution may be, for example, a chloride solution, such as a nickel chloride solution. The concentration of the extractant used in the extraction of the lead ion may be in the range of from 1 to 50%
by volume, and the temperatures of the aqueous solution and the extractant may be from 20 to 60 C. A sulfuric acid solution having a concentration of 0. 5N or more may be used for stripping of lead thus extracted.
The invention relates to, as a second embodiment, a method for removal of a lead ion from a nickel chloride solution comprising (a) a first step of contacting, at least once, a nickel chloride solution containing a lead ion with an organic solvent having a thiophosphinic acid structure, to extract and remove the lead ion; (b) a second step of contacting the organic solvent subjected to extraction of the lead ion with an acidic solution having a pH value lower than that on the extraction and removal of the lead ion and in a range of from 0. 5 to 3. 0, to put back a valuable metal having been extracted along with the lead ion to the nickel chloride solution; and (c) a third step of subjecting the lead ion contained in the extractant to stripping as lead sulfate by using a sulfuric acid solution, and separating the lead sulfate to regenerate the extractant.
In the first step, the nickel chloride solution may have a pH
value of from 1 to 5; the concentration of the extractant used in the extraction of the lead ion may be in the range of from 1 to 50% by volume; and the temperatures of the nickel chloride solution and the extractant may be from 20 to 60 C. In the second step, a volume ratio the organic solvent 0 to the acidic solution A(O/A) may be controlled to a range of from 10/1 to 1/1. In the third step, the sulfuric acid solution used in the stripping has a concentration of 0.5N or more.
DETAIL.ED DESCRIPTION OF THE INVENTTON
The invention is based on the fact that a lead ion has a large affinity with a sulfur compound, and has been made based on the finding in that an organic solvent having a thiophosphinic acid structure has a large affinity with a lead ion, and exhibits high extraction performance even from a chloride solution such as a nickel chloride solution.
Thiophosphinic acid used in the invention has an organic compound having the structure shown by the following chemical structure:
R
I
R - P - OH
S
wherein R represents an alkyl group.
A lead ion is extracted by this organic solvent according to the following equation:
Pb2+ + 2R2PSOH = (R2SO ) Z - Pb + 2H' Therefore, when the pH is higher, the lead ion is better extracted. In the case where the aqueous solution is a nickel chloride solution, the pH value of the aqueous phase, i.e., the nickel chloride solution, is controlled to 1 to 5, preferably from 2 to 4, while it varies depending on the lead ion concentration in the nickel chloride solution and the species of the ions present in combination with the lead ion.
General neutralizing agents can be used to control the pH
value, and examples thereof include neutralizing agents in the form of a solution or a solid, such as an alkali hydroxide, ammonia and a metal carbonate.
The organic solvent can extract not only lead but also iron and zinc, and thus these impurities can also be extracted and removed from the nickel chloride solution as a raw material solution along with lead.
The extractant generally has a high concentration, and if it can be used as it is, a large amount of impurities contained in an aqueous solution, such as a nickel or cobalt solution, can be extracted. However, its viscosity is increased to cause a problem on the extracting operation, and therefore the extractant is generally used after dilution. The degree of dilution is not particularly limited and is determined depending on the concentration of the impurities. In general, the concentration of the extractant is preferably in the range of from 1 to 50% by volume.
The temperature on extraction is not particularly limited.
Raw materials of non-iron metals contain various impurities, and the methods are evaluated on the standard as to whether or not the impurities can be effectively removed.
Such a method is often employed for recovering a non-iron metal that a raw material is dissolved in an acid or an alkali to obtain an aqueous solution containing the objective element and impurities, and then the impurities are respectively removed by an operation, such as neutralization and sulfurization, to obtain a solution containing only the objective element to be recovered. Among the impurities, lead is considered as an element that often should be removed since its content is relatively large.
Lead is generally present in the form of a PbZ+ ion in an aqueous solution. The removal of such a leached lead ion is often conducted by utilizing the small solubility of PbSO4 and PbS. Such methods are practiced in that S2- ion or an SO42" ion is added to the resulting leached solution to form a compound having a small solubility by combination with a lead ion, or in alternative, a lead ion is oxidized from divalent to tetravalent by oxidizing a solution containing the lead ion, and Pb02 thus formed having a small solubility is removed.
For example, in the case where nickel is produced by using nickel matte, the nickel matte is dissolved by chlorine, hydrochloric acid or sulfuric acid. Impurities contained in the resulting solution, such as lead, iron and copper, are then respectively removed, and a pure nickel solution thus obtained is subjected to electrolysis to obtain metallic nickel.
In order to produce metallic nickel having a high purity, the impurities such as lead must be removed to a low concentration before the electrolysis, and particularly, metals, such as lead and copper, having a smaller ionization tendency than nickel are desirably removed to a sufficiently low concentration before the electrolysis.
In the method in which lead is removed in the form of PbSO4, the solubility of these compounds are not sufficiently low, and a lead ion remains in the solution, so that nickel having a high purity is difficult to be produced.
Another method has been proposed, in which lead is removed in the form of a sulfide by adding hydrogen sulfide or sodium sulfide. This method is based on the fact that a sulfide of lead has a higher stability than nickel. However, this method involves problems in operation, in that a toxic gas such as hydrogen sulfide is used, and because a precipitate of NiS is liable to gradually formed due to a slight amount of a hydrogen sulfide gas dissolved in water even after completion of the reaction, the hydrogen sulfide gas must be removed from the solution by deaeration.
Still another method has been proposed, in which lead is removed as a metal by cementation by adding metallic iron or nickel. In this method, lead is subjected to cementation since lead has a smaller ionization tendency than nickel, but cannot be removed effectively because the difference in potential from nickel is small.
Still another method has been proposed, in which lead is removed by oxidation of the solution by using Cl2 gas. In this method, lead is removed in the form of Pb02 having a small solubility by oxidizing the lead ion from divalent to tetravalent. However, since a strong oxidizing agent such as C1Z is used, nickel contained in the solution is also oxidized to form Ni(OH)3, which brings about excessive use of the oxidizing agent. In the chloride solution, since a lead ion forms a complex ion with chlorine to be present in the form of PbC13- and PbC142-, removal of the impurities becomes difficult, and particularly, removal of a lead ion to a low concentration is extremely difficult.
Separation and removal of various metallic ions by using the solvent extraction technique or the ion exchange resin technique is recently practiced, which is also applied to removal of a lead ion. In the adsorption method by an ion exchange resin, for example, removal of a lead ion from a sulfuric acid solution by using a cation exchange resin, and that from a chloride solution by using an anion exchange resin are practiced. However, the adsorption removal using the ion exchange resin is not practical because the adsorption amount of the resin is small, and thus the adsorption and desorption operation should be frequently repeated.
In the method using the solvent extraction technique, there is a report of the use of an acidic extractant. However, in the case where lead is removed from a solution containing nickel and cobalt, since the extractability of these metallic ions is close to that of a lead ion, effective removal of a lead ion is diff icult .
Even when only lead can be selectively extracted, it is not practical because of the following reasons.
The solvent extraction is constituted by three major steps, i.e., extraction, washing and stripping, and lead thus extracted is subjected to the stripping by using a mineral acid, to regenerate an organic solvent.
Hydrochloric acid is frequently used in the stripping from the standpoint of prevention of deterioration of the organic solvent and handling, and a lead chloride solution is obtained as a strip liquor. However, because the solubility of lead chloride is as small as about from 0.9 to 1.6 g/L in 1N to 3N
hydrochloric acid solution, which is used in the stripping, at ordinary temperature, crystals of lead chloride are liable to be deposited, and deposition of the crystals in the equipment and piping may bring about troubles.
In order to operate stably, the lead concentration in the strip liquor should be controlled not to exceed the solubility of lead chloride, and as a result, the stripping should be conducted by using a large amount of an acid solution.
Accordingly, even a strip liquor exhibiting sufficient stripping performance as an acid concentration should be withdrawn from the stripping system to prevent deposition of crystals of lead chloride, and the same amount of a new hydrochloric acid solution should be added. The strip liquor thus withdrawn is generally subjected to a neutralization treatment, and thus the strip liquor having a high acid concentration is disadvantageous since it requires a large amount of a neutralizing agent.
Therefore, even in the case of the organic solvents that can extract lead, a method for removal of a lead ion by using these solvents involves various problems, and there is a difficulty in practical operation.
As described in the foregoing, there has been no method for removal of a lead ion from a nickel chloride solution containing a lead ion in an efficient manner, and development of a method for removal that can be practically conducted has been demanded.
According to the conventional methods, a lead ion cannot be completely removed from a solution containing a lead ion.
SUMMARY OF THE INVENTION
An object of the invention is to solve the problems described above, and to provide a method for removal of a lead ion in that a lead ion is effectively removed from an aqueous solution, such as a nickel chloride solution, containing a lead ion to a low concentration, and an organic solvent can be regenerated in an economical and effective manner.
As a result of extensive investigations made by the inventors to attain the objects described above, it has been found that when an aqueous solution, such as nickel chloride solution, containing a lead ion is made in contact with an organic solvent phase having a thiophosphinic acid structure, a lead ion can be effectively removed. Thus, the invention has been completed.
The invention relates to, as a first embodiment, a method for removal of a lead ion comprising a step of contacting, at least once, an aqueous solution containing a lead ion with an organic solvent having a thiophosphinic acid structure, to extract and remove the lead ion. The aqueous solution may be, for example, a chloride solution, such as a nickel chloride solution. The concentration of the extractant used in the extraction of the lead ion may be in the range of from 1 to 50%
by volume, and the temperatures of the aqueous solution and the extractant may be from 20 to 60 C. A sulfuric acid solution having a concentration of 0. 5N or more may be used for stripping of lead thus extracted.
The invention relates to, as a second embodiment, a method for removal of a lead ion from a nickel chloride solution comprising (a) a first step of contacting, at least once, a nickel chloride solution containing a lead ion with an organic solvent having a thiophosphinic acid structure, to extract and remove the lead ion; (b) a second step of contacting the organic solvent subjected to extraction of the lead ion with an acidic solution having a pH value lower than that on the extraction and removal of the lead ion and in a range of from 0. 5 to 3. 0, to put back a valuable metal having been extracted along with the lead ion to the nickel chloride solution; and (c) a third step of subjecting the lead ion contained in the extractant to stripping as lead sulfate by using a sulfuric acid solution, and separating the lead sulfate to regenerate the extractant.
In the first step, the nickel chloride solution may have a pH
value of from 1 to 5; the concentration of the extractant used in the extraction of the lead ion may be in the range of from 1 to 50% by volume; and the temperatures of the nickel chloride solution and the extractant may be from 20 to 60 C. In the second step, a volume ratio the organic solvent 0 to the acidic solution A(O/A) may be controlled to a range of from 10/1 to 1/1. In the third step, the sulfuric acid solution used in the stripping has a concentration of 0.5N or more.
DETAIL.ED DESCRIPTION OF THE INVENTTON
The invention is based on the fact that a lead ion has a large affinity with a sulfur compound, and has been made based on the finding in that an organic solvent having a thiophosphinic acid structure has a large affinity with a lead ion, and exhibits high extraction performance even from a chloride solution such as a nickel chloride solution.
Thiophosphinic acid used in the invention has an organic compound having the structure shown by the following chemical structure:
R
I
R - P - OH
S
wherein R represents an alkyl group.
A lead ion is extracted by this organic solvent according to the following equation:
Pb2+ + 2R2PSOH = (R2SO ) Z - Pb + 2H' Therefore, when the pH is higher, the lead ion is better extracted. In the case where the aqueous solution is a nickel chloride solution, the pH value of the aqueous phase, i.e., the nickel chloride solution, is controlled to 1 to 5, preferably from 2 to 4, while it varies depending on the lead ion concentration in the nickel chloride solution and the species of the ions present in combination with the lead ion.
General neutralizing agents can be used to control the pH
value, and examples thereof include neutralizing agents in the form of a solution or a solid, such as an alkali hydroxide, ammonia and a metal carbonate.
The organic solvent can extract not only lead but also iron and zinc, and thus these impurities can also be extracted and removed from the nickel chloride solution as a raw material solution along with lead.
The extractant generally has a high concentration, and if it can be used as it is, a large amount of impurities contained in an aqueous solution, such as a nickel or cobalt solution, can be extracted. However, its viscosity is increased to cause a problem on the extracting operation, and therefore the extractant is generally used after dilution. The degree of dilution is not particularly limited and is determined depending on the concentration of the impurities. In general, the concentration of the extractant is preferably in the range of from 1 to 50% by volume.
The temperature on extraction is not particularly limited.
The higher the temperature is, the lower the viscosity of the aqueous solution, such as a nickel chloride solution, and the extractant, to shorten the period of time necessary to separate the aqueous phase and the organic phase after extraction, and therefore the extraction is preferably conducted at a high temperature. Considering evaporation and ignition of the extractant and a diluent to be added to decrease the viscosity of the diluent, the operation is preferably conducted at a temperature of from 20 to 60 C .
According to the step described above, a lead ion can be effectively extracted and removed. In order to remove a lead ion from a nickel chloride solution with economical and effective regeneration of an organic solvent, it is preferred that the step described above is used as the first step, and the following second and third steps are employed.
The second step of the invention is to recover valuable metals, such as cobalt, from the organic solvent, with which a lead ion has been extracted. Metallic ions, such as cobalt, having the relatively similar extracting characteristics as lead are co-extracted to the organic solvent on the extraction of lead. Such valuable metals, such as cobalt, can be put back to the aqueous phase (i.e., the nickel chloride solution) by contacting the acidic solution with the organic solvent.
In other words, the nickel chloride solution as the raw material solution contains valuable metals, such as cobalt, in many cases. Because these metallic ions can be extracted from the nickel chloride solution having a pH value higher than that on the extraction of lead, they can be put back to the aqueous phase ( i. e., the nickel chloride solution) by washing with the acidic solution at a pH value lower than that of the extraction of the lead ion and being controlled to a range of from 0.5 to 3Ø
The reason why the pH is controlled to the range of from 0.5 to 3.0 is that when pH is lower than 0.5, lead also moves from the organic solvent to the aqueous phase, and if pH is higher than 3.0, the washing efficiency is decreased, and it is difficult to completely recover the valuable metals, such as cobalt.
Although the valuable metals, such as cobalt, can be effectively recovered by using a large amount of the acidic solution for washing, there arises a problem on a post-treatment of the recovered solution. The recovered solution is subjected to a neutralizing treatment or is repeatedly treated after mixing with the nickel chlorides solution as the raw material solution containing the impurities, and therefore the amount of the recovered solution is preferably as small as possible.
In the second step, the volume ratio of the organic solvent O to the acidic solution A(O/A) is not particularly limited, but is preferably controlled to a range of from 10/1 to 1/1 because of the reason described above.
According to the step described above, a lead ion can be effectively extracted and removed. In order to remove a lead ion from a nickel chloride solution with economical and effective regeneration of an organic solvent, it is preferred that the step described above is used as the first step, and the following second and third steps are employed.
The second step of the invention is to recover valuable metals, such as cobalt, from the organic solvent, with which a lead ion has been extracted. Metallic ions, such as cobalt, having the relatively similar extracting characteristics as lead are co-extracted to the organic solvent on the extraction of lead. Such valuable metals, such as cobalt, can be put back to the aqueous phase (i.e., the nickel chloride solution) by contacting the acidic solution with the organic solvent.
In other words, the nickel chloride solution as the raw material solution contains valuable metals, such as cobalt, in many cases. Because these metallic ions can be extracted from the nickel chloride solution having a pH value higher than that on the extraction of lead, they can be put back to the aqueous phase ( i. e., the nickel chloride solution) by washing with the acidic solution at a pH value lower than that of the extraction of the lead ion and being controlled to a range of from 0.5 to 3Ø
The reason why the pH is controlled to the range of from 0.5 to 3.0 is that when pH is lower than 0.5, lead also moves from the organic solvent to the aqueous phase, and if pH is higher than 3.0, the washing efficiency is decreased, and it is difficult to completely recover the valuable metals, such as cobalt.
Although the valuable metals, such as cobalt, can be effectively recovered by using a large amount of the acidic solution for washing, there arises a problem on a post-treatment of the recovered solution. The recovered solution is subjected to a neutralizing treatment or is repeatedly treated after mixing with the nickel chlorides solution as the raw material solution containing the impurities, and therefore the amount of the recovered solution is preferably as small as possible.
In the second step, the volume ratio of the organic solvent O to the acidic solution A(O/A) is not particularly limited, but is preferably controlled to a range of from 10/1 to 1/1 because of the reason described above.
The third step of the invention is to remove lead contained in the organic solvent by the stripping, in the form of lead sulfate, by using a sulfuric acid solution, to regenerate the organic solvent.
The problems occurring in the conventional stripping steps are, as described above, that the lead concentration in the strip liquor should be controlled not to exceed the low solubility of the lead compound, and thus a large amount of an acidic solution used for stripping is necessary. Accordingly, even strip liquor exhibiting sufficient stripping performance as an acid concentration should be used in a large amount for the neutralization treatment.
In the invention, therefore, the stripping is conducted by contacting the organic solvent, by which lead has been extracted, with a sulfuric acid solution, to regenerate the organic solution. The stripping step of the invention is to generate lead sulfate through a reaction of lead extracted by the organic solvent and sulfuric acid. Since the solubility of the sulfuric acid is extremely small, the lead contained in the organic solvent can be completely subjected to the stripping by using the sulfuric acid solution, and the lead sulfate thus produced can be easily removed by filtration. Thus, the neutralization treatment of the strip liquor, which has been necessary in the conventional processes, is not necessary, and the separation of the aqueous phase and the organic phase after the strip liquor can be conducted under good conditions.
Since lead is subjected to the stripping by the formation of lead sulfate, most of the proportion of sulfuric acid contained in the strip liquor is not consumed, and therefore the sulfuric acid solution can be again used for stripping after removing lead sulfate and adding and supplying sulfuric acid in an amount corresponding to the lead sulfate produced.
The higher the concentration of the sulfuric acid solution is, the higher the efficiency of the stripping of lead. It is therefore preferred to use a sulfuric acid solution having a concentration of 0. 5N or more (corresponding to about pH 0. 5), and more preferably 1. ON or more (corresponding to about pH 0).
The lead sulfate formed in the method of the invention has good filtering property, and the amount of the organic solvent attached to the filtered lead sulfate can be ignored. For example, in the case where the extractant diluted to 20% by volume is used for extraction of lead, when lead sulfate formed on stripping of sulfuric acid is filtered by suction, the concentration of the extractant in the lead sulfate is as small as 1 to 2%.
In the case where the extractant attached to lead sulfate should be completely recovered, the concentration of the extractant in the lead sulfate can be lowered to 0. 1% or lower by washing the lead sulfate with an organic solvent used for dilution of the extractant.
The problems occurring in the conventional stripping steps are, as described above, that the lead concentration in the strip liquor should be controlled not to exceed the low solubility of the lead compound, and thus a large amount of an acidic solution used for stripping is necessary. Accordingly, even strip liquor exhibiting sufficient stripping performance as an acid concentration should be used in a large amount for the neutralization treatment.
In the invention, therefore, the stripping is conducted by contacting the organic solvent, by which lead has been extracted, with a sulfuric acid solution, to regenerate the organic solution. The stripping step of the invention is to generate lead sulfate through a reaction of lead extracted by the organic solvent and sulfuric acid. Since the solubility of the sulfuric acid is extremely small, the lead contained in the organic solvent can be completely subjected to the stripping by using the sulfuric acid solution, and the lead sulfate thus produced can be easily removed by filtration. Thus, the neutralization treatment of the strip liquor, which has been necessary in the conventional processes, is not necessary, and the separation of the aqueous phase and the organic phase after the strip liquor can be conducted under good conditions.
Since lead is subjected to the stripping by the formation of lead sulfate, most of the proportion of sulfuric acid contained in the strip liquor is not consumed, and therefore the sulfuric acid solution can be again used for stripping after removing lead sulfate and adding and supplying sulfuric acid in an amount corresponding to the lead sulfate produced.
The higher the concentration of the sulfuric acid solution is, the higher the efficiency of the stripping of lead. It is therefore preferred to use a sulfuric acid solution having a concentration of 0. 5N or more (corresponding to about pH 0. 5), and more preferably 1. ON or more (corresponding to about pH 0).
The lead sulfate formed in the method of the invention has good filtering property, and the amount of the organic solvent attached to the filtered lead sulfate can be ignored. For example, in the case where the extractant diluted to 20% by volume is used for extraction of lead, when lead sulfate formed on stripping of sulfuric acid is filtered by suction, the concentration of the extractant in the lead sulfate is as small as 1 to 2%.
In the case where the extractant attached to lead sulfate should be completely recovered, the concentration of the extractant in the lead sulfate can be lowered to 0. 1% or lower by washing the lead sulfate with an organic solvent used for dilution of the extractant.
Examples of the invention will be described below.
By using a chloride solution containing 163 g/L of nickel, 0.041 g/L. of lead, 2.87 g/L of cobalt and 0.011 g/L of zinc as a raw material nickel chloride solution, countercurrent extraction with two-stage extraction and two-stage washing was conducted. At this time, thiophosphinic acid, wherein the alkyl group was C8H17, was used as an extractant after diluting with an aromatic organic solvent (Cleansol G, trade name, by Nippon Oil Company, Limited) to a concentration of 20% by volume.
The ratio of the organic solvent (0) to the aqueous phase (A) (O/A) on extraction was 1, and the pH was adjusted to 2.5 with a sodium hydroxide solution of 100 g/L.
The washing of the organic solvent was conducted at a ratio O/A of 2/1, and the pH was adjusted to pH 1.5 with hydrochloric acid of a concentration of 3N. The washing liquid was withdrawn to the outside of the system without putting back to the original solution, and was subjected to a test.
On practical operation, it is put back to the original solution to recover Co, or in alternative is subjected to a recovering treatment of Co outside the system.
By using a chloride solution containing 163 g/L of nickel, 0.041 g/L. of lead, 2.87 g/L of cobalt and 0.011 g/L of zinc as a raw material nickel chloride solution, countercurrent extraction with two-stage extraction and two-stage washing was conducted. At this time, thiophosphinic acid, wherein the alkyl group was C8H17, was used as an extractant after diluting with an aromatic organic solvent (Cleansol G, trade name, by Nippon Oil Company, Limited) to a concentration of 20% by volume.
The ratio of the organic solvent (0) to the aqueous phase (A) (O/A) on extraction was 1, and the pH was adjusted to 2.5 with a sodium hydroxide solution of 100 g/L.
The washing of the organic solvent was conducted at a ratio O/A of 2/1, and the pH was adjusted to pH 1.5 with hydrochloric acid of a concentration of 3N. The washing liquid was withdrawn to the outside of the system without putting back to the original solution, and was subjected to a test.
On practical operation, it is put back to the original solution to recover Co, or in alternative is subjected to a recovering treatment of Co outside the system.
Table 1 Liquid Pb 1L Co (g/L) Zn /L
Nickel chloride solution as raw material 0.041 2.87 0.011 Nickel chloride solution after extraction < 0.001 0.62 < 0.001 Organic solvent after washing 0.041 0.041 0.011 It was understood from Table 1 that not only lead but also zinc were completely extracted. The co-extraction amount of cobalt into the organic solvent could be suppressed to an extremely low level.
By using a chloride solution containing 154 g/L of nickel, 0.034 g/L of lead, 2.54 g/L of cobalt and 0.011 g/L of zinc as a raw material nickel chloride solution, countercurrent extraction with two-stage extraction was conducted. At this time, as similar to Example 1, thiophosphinic acid, wherein the alkyl group was CeHl7, was used as an extractant after diluting to a concentration of 20% by volume.
The ratio of the organic solvent (0) to the aqueous phase (A) (O/A) on extraction was 1/10, and the pH was adjusted to 3.0 with a sodium hydroxide solution of 200 g/L.
Table 2 Liquid Pb (g/L) Co (g/L) Zn (g/L) Nickel chloride solution as raw material 0.034 2.54 0.011 Nickel chloride solution after extraction < 0.001 2.04 < 0.001 Organic solvent after washing 0.33 3.18 0.11 It was understood from Table 2 that lead could be extracted even when the ratio of organic solvent to the aqueous phase (O/A) was 1/10 to make the amount of organic solvent extremely small with respect to the aqueous phase, and accordingly the amount of cobalt co-extracted could be decreased by limiting the amount of the organic solvent used.
In Example 2, the extraction ratio of cobalt was suppressed to 12.5%, and by using a small amount of the organic solvent, recovering of cobalt could be easy on washing of the organic phase with diluted hydrochloric acid as a post-treatment.
An extraction operation was conducted by using an organic solvent of thiophosphinic acid, wherein the alkyl group was CeH171 after diluting to a concentration of 20% by volume prepared in the same manner as in Example 1, so that the organic solvent contained 5.93 g/L of lead. It was shaken with sulfuric acid solutions having different concentrations, respectively, for minutes, to conduct stripping. The ratio of organic phase to the aqueous phase (O/A) was 1/1.
Table 3 Initial strip solution Stripping ratio of Pb Pb concentration in H SO concentration) stdp liquor 0.1 N 65 0.005 0.5N 92 0.004 1.ON 98 0.004 3.ON 99 0.004 It was understood from Table 3 that lead could be effectively removed by stripping by using sulfuric acid having a concentration of 0.5N or higher. Because the lead that had been subjected to the stripping was in the form of lead sulfate, the concentration of lead in the strip liquor was low.
Therefore, it can be used as an initial strip solution by adding and supplying sulfuric acid in an amount corresponding to the lead sulfate produced.
When the sulfuric acid solutions having different concentrations were used as in Table 3, the separation between the aqueous phase and the organic phase after the stripping was good, and they were completely separated to two phases within 2 minutes after completion of the stripping.
By using a chloride solution containing 154 g/L of nickel, 0.034 g/L of lead, 2.54 g/L of cobalt and 0.011 g/L of zinc as a raw material nickel chloride solution, countercurrent extraction with two-stage extraction was conducted. At this time, as similar to Example 1, thiophosphinic acid, wherein the alkyl group was CeHI7, was used as an extractant after diluting to a concentration of 20% by volume.
The ratio of the organic solvent (O) to the aqueous phase (A) (O/A) on extraction was 1/10, and the pH was adjusted to 3.5 by adding nickel carbonate powder.
The organic solvent containing lead, zinc and a part of nickel and cobalt contained in the raw material nickel chloride solution obtained through the extraction step was subjected to countercurrent two-stage washing with adjusting the pH of the aqueous phase to 1.0 with hydrochloric acid having a concentration of 3N under the condition of O/A of 5/1.
The washing liquid was withdrawn to the outside of the system without putting back to the original solution, and was subjected to a test.
On practical operation, it is put back to the original solution to recover Co, or in alternative is subjected to a recovering treatment of Co outside the system.
The organic solvent after washing was subjected to stripping with a sulfuric acid solution having a concentration of 3N at O/A of 1/1. In order to remove lead sulfate thus produced, both the aqueous phase and the organic solvent were filtrated.
0.43 g of lead sulfate was recovered filtration per 1 L
of the organic solvent after washing. The compositions of the liquids in the preceding steps are shown in Table 4.
Table 4 Species of liquid Concentration /L
Step Ni Pb Zn Co Nickel chloride solution as raw material 154 0.034 0.011 2.54 Extraction Nickel chloride solution after extraction 153 < 0.001 < 0.001 1.60 Organic solvent after extraction 0.59 0.35 0.11 4.87 Washing Organic solvent after washing 0.009 0.34 0.11 0.003 Stri in Organic solvent after strip in < 0.001 0.045 < 0.001 < 0,001 pp g Strip solution 0.009 0.004 0.11 0.003 It was understood from Table 4 that lead could be effectively removed from a concentrated raw material nickel chloride solution, and an organic solvent with small amounts of various impurities could be regenerated.
According to the invention described in the foregoing, a method for removal of a lead ion can be provided in that a lead ion is effectively removed from an aqueous solution, such as a nickel chloride solution, containing a lead ion to a low concentration, and an organic solvent can be regenerated in an economical and effective manner.
Nickel chloride solution as raw material 0.041 2.87 0.011 Nickel chloride solution after extraction < 0.001 0.62 < 0.001 Organic solvent after washing 0.041 0.041 0.011 It was understood from Table 1 that not only lead but also zinc were completely extracted. The co-extraction amount of cobalt into the organic solvent could be suppressed to an extremely low level.
By using a chloride solution containing 154 g/L of nickel, 0.034 g/L of lead, 2.54 g/L of cobalt and 0.011 g/L of zinc as a raw material nickel chloride solution, countercurrent extraction with two-stage extraction was conducted. At this time, as similar to Example 1, thiophosphinic acid, wherein the alkyl group was CeHl7, was used as an extractant after diluting to a concentration of 20% by volume.
The ratio of the organic solvent (0) to the aqueous phase (A) (O/A) on extraction was 1/10, and the pH was adjusted to 3.0 with a sodium hydroxide solution of 200 g/L.
Table 2 Liquid Pb (g/L) Co (g/L) Zn (g/L) Nickel chloride solution as raw material 0.034 2.54 0.011 Nickel chloride solution after extraction < 0.001 2.04 < 0.001 Organic solvent after washing 0.33 3.18 0.11 It was understood from Table 2 that lead could be extracted even when the ratio of organic solvent to the aqueous phase (O/A) was 1/10 to make the amount of organic solvent extremely small with respect to the aqueous phase, and accordingly the amount of cobalt co-extracted could be decreased by limiting the amount of the organic solvent used.
In Example 2, the extraction ratio of cobalt was suppressed to 12.5%, and by using a small amount of the organic solvent, recovering of cobalt could be easy on washing of the organic phase with diluted hydrochloric acid as a post-treatment.
An extraction operation was conducted by using an organic solvent of thiophosphinic acid, wherein the alkyl group was CeH171 after diluting to a concentration of 20% by volume prepared in the same manner as in Example 1, so that the organic solvent contained 5.93 g/L of lead. It was shaken with sulfuric acid solutions having different concentrations, respectively, for minutes, to conduct stripping. The ratio of organic phase to the aqueous phase (O/A) was 1/1.
Table 3 Initial strip solution Stripping ratio of Pb Pb concentration in H SO concentration) stdp liquor 0.1 N 65 0.005 0.5N 92 0.004 1.ON 98 0.004 3.ON 99 0.004 It was understood from Table 3 that lead could be effectively removed by stripping by using sulfuric acid having a concentration of 0.5N or higher. Because the lead that had been subjected to the stripping was in the form of lead sulfate, the concentration of lead in the strip liquor was low.
Therefore, it can be used as an initial strip solution by adding and supplying sulfuric acid in an amount corresponding to the lead sulfate produced.
When the sulfuric acid solutions having different concentrations were used as in Table 3, the separation between the aqueous phase and the organic phase after the stripping was good, and they were completely separated to two phases within 2 minutes after completion of the stripping.
By using a chloride solution containing 154 g/L of nickel, 0.034 g/L of lead, 2.54 g/L of cobalt and 0.011 g/L of zinc as a raw material nickel chloride solution, countercurrent extraction with two-stage extraction was conducted. At this time, as similar to Example 1, thiophosphinic acid, wherein the alkyl group was CeHI7, was used as an extractant after diluting to a concentration of 20% by volume.
The ratio of the organic solvent (O) to the aqueous phase (A) (O/A) on extraction was 1/10, and the pH was adjusted to 3.5 by adding nickel carbonate powder.
The organic solvent containing lead, zinc and a part of nickel and cobalt contained in the raw material nickel chloride solution obtained through the extraction step was subjected to countercurrent two-stage washing with adjusting the pH of the aqueous phase to 1.0 with hydrochloric acid having a concentration of 3N under the condition of O/A of 5/1.
The washing liquid was withdrawn to the outside of the system without putting back to the original solution, and was subjected to a test.
On practical operation, it is put back to the original solution to recover Co, or in alternative is subjected to a recovering treatment of Co outside the system.
The organic solvent after washing was subjected to stripping with a sulfuric acid solution having a concentration of 3N at O/A of 1/1. In order to remove lead sulfate thus produced, both the aqueous phase and the organic solvent were filtrated.
0.43 g of lead sulfate was recovered filtration per 1 L
of the organic solvent after washing. The compositions of the liquids in the preceding steps are shown in Table 4.
Table 4 Species of liquid Concentration /L
Step Ni Pb Zn Co Nickel chloride solution as raw material 154 0.034 0.011 2.54 Extraction Nickel chloride solution after extraction 153 < 0.001 < 0.001 1.60 Organic solvent after extraction 0.59 0.35 0.11 4.87 Washing Organic solvent after washing 0.009 0.34 0.11 0.003 Stri in Organic solvent after strip in < 0.001 0.045 < 0.001 < 0,001 pp g Strip solution 0.009 0.004 0.11 0.003 It was understood from Table 4 that lead could be effectively removed from a concentrated raw material nickel chloride solution, and an organic solvent with small amounts of various impurities could be regenerated.
According to the invention described in the foregoing, a method for removal of a lead ion can be provided in that a lead ion is effectively removed from an aqueous solution, such as a nickel chloride solution, containing a lead ion to a low concentration, and an organic solvent can be regenerated in an economical and effective manner.
Claims (6)
1. A method for removal of a lead ion from a nickel chloride solution comprising:
(a) a first step of contacting, at least once, a nickel chloride solution containing a lead ion with an organic solvent having a thiophosphinic acid structure, to extract and remove said lead ion;
(b) a second step of contacting said organic solvent subjected to extraction of said lead ion with an acidic solution having a pH value lower than that on said extraction and removal of said lead ion and in a range of from 0.5 to 3.0, to put back a valuable metal having been extracted along with said lead ion to said nickel chloride solution; and (c) a third step of subjecting said lead ion contained in said extractant to stripping as lead sulfate by using a sulfuric acid solution, and separating said lead sulfate to regenerate said extractant.
(a) a first step of contacting, at least once, a nickel chloride solution containing a lead ion with an organic solvent having a thiophosphinic acid structure, to extract and remove said lead ion;
(b) a second step of contacting said organic solvent subjected to extraction of said lead ion with an acidic solution having a pH value lower than that on said extraction and removal of said lead ion and in a range of from 0.5 to 3.0, to put back a valuable metal having been extracted along with said lead ion to said nickel chloride solution; and (c) a third step of subjecting said lead ion contained in said extractant to stripping as lead sulfate by using a sulfuric acid solution, and separating said lead sulfate to regenerate said extractant.
2. A method for removal of a lead ion from a nickel chloride solution as claimed in claim 1, wherein said nickel chloride solution in said first step has a pH value of from 1 to 5.
3. A method for removal of a lead ion from a nickel chloride solution as claimed in claim 1, wherein said extractant used in said extraction of said lead ion in said first step is in a range of from 1 to 50% by volume.
4. A method for removal of a lead ion from a nickel chloride solution as claimed in claim 1 or 3, wherein a temperature of said nickel chloride solution and said extractant in said first step is from 20 to 60°C.
5. A method for removal of a lead ion from a nickel chloride solution as claimed in any one of claims 1 to 4, wherein a volume ratio of said organic solvent O to said acidic solution A(O/A) in said second step is controlled to a range of from 10/1 to 1/1.
6. A method for removal of a lead ion from a nickel chloride solution as claimed in any one of claims 1 to 5, wherein said sulfuric acid solution used in said stripping in said third step has a concentration of 0.5N or more.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10-94117 | 1998-03-23 | ||
| JP9411798A JPH11267634A (en) | 1998-03-23 | 1998-03-23 | Method of removing lead ion |
| JP10-199687 | 1998-06-30 | ||
| JP19968798 | 1998-06-30 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2265068A1 CA2265068A1 (en) | 1999-09-23 |
| CA2265068C true CA2265068C (en) | 2008-10-21 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002265068A Expired - Fee Related CA2265068C (en) | 1998-03-23 | 1999-03-09 | Method for removal of lead ion |
Country Status (3)
| Country | Link |
|---|---|
| AU (1) | AU738180B2 (en) |
| CA (1) | CA2265068C (en) |
| RU (1) | RU2169601C2 (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| RU2501868C2 (en) * | 2012-03-30 | 2013-12-20 | Лидия Алексеевна Воропанова | Extraction of lead ions from aqueous solution by vegetable oils |
| RU2600041C1 (en) * | 2015-06-25 | 2016-10-20 | Федеральное государственное бюджетное учреждение науки Институт химии и технологии редких элементов и минерального сырья им. И.В. Тананаева Кольского научного центра Российской академии наук (ИХТРЭМС КНЦ РАН) | Method of extracting lead from nickel-containing chloride solution |
-
1999
- 1999-03-09 CA CA002265068A patent/CA2265068C/en not_active Expired - Fee Related
- 1999-03-22 RU RU99105844/12A patent/RU2169601C2/en not_active IP Right Cessation
- 1999-03-23 AU AU21345/99A patent/AU738180B2/en not_active Ceased
Also Published As
| Publication number | Publication date |
|---|---|
| AU738180B2 (en) | 2001-09-13 |
| AU2134599A (en) | 1999-10-07 |
| CA2265068A1 (en) | 1999-09-23 |
| RU2169601C2 (en) | 2001-06-27 |
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