CA1112460A - Solvent extraction process - Google Patents
Solvent extraction processInfo
- Publication number
- CA1112460A CA1112460A CA297,819A CA297819A CA1112460A CA 1112460 A CA1112460 A CA 1112460A CA 297819 A CA297819 A CA 297819A CA 1112460 A CA1112460 A CA 1112460A
- Authority
- CA
- Canada
- Prior art keywords
- cobalt
- nickel
- thiocyanate
- solution
- raffinate
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D11/00—Solvent extraction
- B01D11/04—Solvent extraction of solutions which are liquid
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B3/00—Extraction of metal compounds from ores or concentrates by wet processes
- C22B3/20—Treatment or purification of solutions, e.g. obtained by leaching
- C22B3/26—Treatment or purification of solutions, e.g. obtained by leaching by liquid-liquid extraction using organic compounds
- C22B3/28—Amines
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B3/00—Extraction of metal compounds from ores or concentrates by wet processes
- C22B3/20—Treatment or purification of solutions, e.g. obtained by leaching
- C22B3/26—Treatment or purification of solutions, e.g. obtained by leaching by liquid-liquid extraction using organic compounds
- C22B3/33—Cyanic acids, derivatives thereof
-
- 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
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
Abstract
ABSTRACT OF THE DISCLOSURE
Loss of thiocyanate ions used in solvent extraction processes is minimized by adjusting the acid concentrations of aqueous process solutions to repress substantially completely ionization of the thiocyanate and contacting the aqueous process solutions with a liquid organic solvent to incorporate the thiocyanate therein as hydrogen thio-cyanate.
In a specific example, cobalt is separated from a nickel process solution by contacting the process solution with an organic extractant of methyl isobutyl ketone having hydrogen thiocyanate dissolved therein. The cobalt-loaded organic extractant is stripped of its cobalt values by contact with a concentrated sulfuric acid solution, which minimizes losses of thiocyanate to the stripping solution, and produces a sulfuric acid solution containing cobalt, which can be treated to crystallize cobalt sulfate and to regenerate a concentrated sulfuric acid solution that can be recycled to the stripping operation. Concentrated sul-furic acid is added to the nickel-containing raffinate which is then contacted with the stripped organic extractant to scavenge hydrogen thiocyanate from the raffinate. The thiocyanate-free raffinate is treated for nickel and sul-furic acid recovery.
(1)
Loss of thiocyanate ions used in solvent extraction processes is minimized by adjusting the acid concentrations of aqueous process solutions to repress substantially completely ionization of the thiocyanate and contacting the aqueous process solutions with a liquid organic solvent to incorporate the thiocyanate therein as hydrogen thio-cyanate.
In a specific example, cobalt is separated from a nickel process solution by contacting the process solution with an organic extractant of methyl isobutyl ketone having hydrogen thiocyanate dissolved therein. The cobalt-loaded organic extractant is stripped of its cobalt values by contact with a concentrated sulfuric acid solution, which minimizes losses of thiocyanate to the stripping solution, and produces a sulfuric acid solution containing cobalt, which can be treated to crystallize cobalt sulfate and to regenerate a concentrated sulfuric acid solution that can be recycled to the stripping operation. Concentrated sul-furic acid is added to the nickel-containing raffinate which is then contacted with the stripped organic extractant to scavenge hydrogen thiocyanate from the raffinate. The thiocyanate-free raffinate is treated for nickel and sul-furic acid recovery.
(1)
Description
~AC~GROU~'D OF T~E I~ ;TION
__ _ _ The present invention relates to a liquid-liquid extraction ~rocess and, more particularly, to an improved ' method of preventing losses of valuable ions used in liquid organic extraction processes.
~lany processes for utilizing liquid extraction techni-ques in treating process solutions to separate one metal value from another metal value exist. Although such liqùid-liquid extraction processes are highly effective in separa-ting one metal value fro~ another metal value, the loss of expensive reagents to tne raffinate and/or to the stripping solution has made the liquid-liquid extraction techni~ues less attractive economically. Reagent costs associated ~ with the recovery of metal values from both the loaded - 15 extractant and the rafrinate have also made these processes less attractive on a co~mercial basis. Losses of v~lua~le or~anic extractant components and the non-regenerative uses o~her reagents have made liquid extraction processes less com2etitive wlth al,ernative methods for separating ~n and/or recovering metal values from aqueous process solu-~iOI~ S .
.
t2) .. . .
~RIEF SUMMARY OF THE INVENTION
- The present invention relates generally to a process for minimizing losses of thiocyanate ions used in solven~
extraction processes to aqueous process solutions. Mineral acid is added to the aqucous process solution to aepress substantially completely ionization of the thiocyanate and to form hydrogen thiocyanate and the aqueous process solu-tion is contacted with a liquid organic solvent to extract the hydrogen thiocyanate.
In one embodiment, an acidic process solution contain-ing two metal values, one of which is complexible by thio-cyanate ions, is contacted with a liquid organic extractant of hydrogen thiocyanate dissolved in a water-immiscible organic solvent to load the extractant with the complexible metal and to produce a raffinate containing the other metal, the loaded extractant is contacted with a sufficiently con-centrated mineral aci~ to strip the complexible metal there-from without dissolving significant amounts of hydrogen thiocyanate in the mineral acid solution. The complexible metal value is recovered by crystallization which also regenerates a concentrated mineral acid solution for further stripping. The acidity of the raffinate is increased to depress the ionization of any hydrogen thiocyanate dissolved therein, and the raffinate is contacted with the stripped extractant to scavenge the hydrogen thiocyanate. The other metal value is recovered by crystallization which regenerates a concentrated acid solution which is recycled to increase the acidity of further amounts of the raf~inate.
(3) ,;, , ~
More particularly, the invention resides in a process for extracting cobalt from an aqueous process solution contain-ing nickel which comprises extracting cobalt from the aqueous solution by contacting the aqueous solution with an organic extractant of a water-immiscible organic solvent of at least one member selected from the group consisting of ketones, esters and alcohols having hydrogen thiocyanate dissolved therein to produce a nickel-containing raffinate and an organic extractant loaded with cobalt, and contacting the loaded extractant with an aqueous solution of a mineral acid having a concentration of at least about 16 N whereby cobalt is recovered as a salt of the mineral acid and the organic extractant is regenerated with minimal thiocyanate losses.
DESCRIPTION OF THE DRAWING
.
Figure 1 is a flowsheet of a process incorporating the process in accordance with the present invention; and - 3a -~L ~ P r . `J S~ ~J ;-3 ~`igur~ ~ is ~ flowsheet of an alternative embodiment of the pr~sent in~rention.
DET~IL~D ~F~CRIPTION
Th~ process in accordance with the present invention 5 can be employed in any process employing solvent extracti~,n in which thiocyanate complexes are formed to provide the reauisite solubility t~ifferentials. However, the present invention will be described in conjunction with the separa-tion of cobalt from nickel-containing aciQic pr~cess solu-1~ tions by use of liquid organic extractants containing hydrogen thioc~anate. Other examples of metal separation that can be effected by practice of the present invent~on include beryllium from aluminum and hafnium from zirconium.
Nickel process solutions having acid strengths up to a~o~t S normal (N) can be treated by the process in ac~or-dance with the present invention to separate cobalt from the nickel process solution. A typical nonlimiting example of an a~ueous nickel process solution is a leach so~ution having a pH value of about 3.5 and containin~ 40 grams per liter tt~pl) nic~el and between 2 and 20 gpl co~alt.
Cokalt is extracted from the nickel process solutio~
~,y contacting the process solution with an organic extractan~
of hydrogen thiocyanate dissolved in a water-immiscible v~anic solvent. This extraction can be conducted in any appararus that provides good liquid-liquid contact. For e~anple, the process can be conducted in packed columns, p~rforatod plate columns, or a series of mixer-settlersr ~ate~-im~isci~le organic sol~-ents that can be employed i~lclu~e Xetones~ esters and alcohols. Methyl iso~utyl 3~t keto~e is ad~antageously used as it is hi~hly ef icient in (4) in extrac'illg co~al~ thiocyanate complexes from nickel-containin~ aqueous solutions. Another ad~antageous water-immiscible organic solvent is ethyl acetate.
Although it is advantageol~s to employ an organic S extractant of hydrogen thiocyanate dissolved in a water-im~iscihle organic solvent, cobalt can also be extracted from nickel containing process solutions by adding water-soluble ~hiocyanate compounds, such as calcium thiocyanate, sodium thiocyanate, and potassium thiocyanate to the nickel-1~ ccn~aining process solutions to form cobalt thiocyanate complexes in the aqueous phase and then contacting ~he aqueous phase with a water-immiscible organic solvent to extract the cobalt thiocyanate complexes from the aqueous phase in~o ~he organic solvent. This latter embodiment is effective 1~ b~t large amounts of thiocyanate compounds must be adde~ to the aqueous phase to c~mplex the cobalt values. When hydrogen thiocyanate ~s dissol~ed in the organic solvent comp~ratively small quantities of thiocyanate ions are reauired.
As noted above, it is advantageous to incorporate hydro-gen thiocyanate in the orsanic solvent before contacting the nickel process solution with the organic extractant. Hyd~o-gen thiocyanate is incorporate~ in the organic solvent in amounts between about O gpl and about 70Q gpl, advantageously, in amounts between about 100 gpl and about 450 gpl. Organic extractants containing hydrogen thiocyan~te within the fore~oing ranges are highly e~fective in ~xtracting cobalt from nick~l-containing process solutions while minimizing thiocyanate losses to the raffinate.
'~he extraction process ~rodllces a subs~antially cobal.-3~ free ra~finate ard a cobalt-loaded organic extr~ctant.
( ~ ) T~e raffinat2 is treated for nickel recovery, and the cobalt-load~d or~anic ~x~ractant is stripped of its cobalt values t~ regenera~ the organic extractant. AdvantageQusly, a mine~al ~cid is added to the raffinate to increase the 5 C concentration of this solution to~value of at least abou~ 5 N
al~d then the raffinate is contacted with the organic extractant regenerated in the stripping operation to recover any thio-cyanate ions dissolved in the raffinate.
Alternatively, the ra~finate can be trea-ted with a second organic Pxtr~ctant comprising an amine or a quaternary ammonium cor.pound dissolved in a water-immiscible organic solvent to recover any dissolved thiocyanate values, as aescribed more ul y hereinzfter. -The loaded organic extractant is advantageously scrubbed with a weak acid solution, i.e., an aqueous mineral acid 501u-tion having a normality of less than ~bout 5~ Contact of the loade2 organic extractant with weak mineral acid solutions scrubs any nickel contained in the organic extrac-ant thereby insuring that the cobalt product obtai.led from the organic 2U extrac~ant is substantially nickel ~ree. Aci~ scrubbing of the loade~ organic extraction is ef~cctive in removing suffi-cie~t amounts of nickel so that the final cobalt product has a cobalt to nickel ratio of at least about 2000:1. The scrubb-ng solution can be recycled to the nic~el process ~5 solution to return the nickel values to the nicXel circuit.
The scrubbed, loaded extractant is contacted with an aqueous mineral acid solution having a normality greater than about 16. ~dvanta~eously, the loaded extractant is contacted ~7ith sul,uric acid solutions at concentration between about N and about 21 N. Upon contact wi~h concentrated sul~uric acid7 cob~lt is back e~tracted into the sulfuric acid sol~Lion and ~ile organic extractan-t is rec,en~rated for reuse ~) ~ ~ i in ~he extrclctiorl stage Stripping with concentrated aq~e~us solutions of mineral acids is an advantageous feature of the present invention. Stripping with concentrated mineral aciA solutions minimizes losses of thiocyanate to the stripping solution.
Co~alt contained in the stripping solution is advanta-geou,ly recovered by crystallization. For exam~le, cobalt can be crystallized from the stripping solution by increasing the acid concentration thereof to diminish cobalt solubility 1~ or by the combination of increasing the acid concentration whil_ lowering th~ temperature of the solution to again lower cobalt ~olubility. Crystallization can also be accomplished by heatin~ the stripping solution to vaporize water which increases the acid concentrations to the point that cobalt is precipi~ated.
Cr~stallization by hea.ing has the advantage of also vaporizing any organic solvent which can be recovered and recycled to the proces3. Crystallization of cobalt from the stripping solu-tion regenerates a concentrated mineral acid solution which can be recycled to the stripping operation. Thus, the only mineral acid ~hat has to be added to the system is an amount equivalent to that xemove~ by crystallization.
As noted hereinbefore, the raffinate is treated for nic~el recov~ry. Advantageously, sufficient mineral acid is added to the raffinate to increase its acid concentration ^'S to at leæst about ~.5 N, and advantageously between about 4.5 ~T and 14 N. The raffinate with its aci~ content so adjusted is contarted with the regenerated orqanic extractant Irom, the stripping operation whereby any thiocyanate contain-ed in the -affinate is reccvered in the regenerated or~anic 3~ extractant. The treatment of the raffinate with mineral acid ~nd subs~quen~ coniact with the resenerated organic extractant along with the stripping with _oncent~ated ~ineral acids minimizes 1GSS of the metal complexing constituents.
The raffinate after ~.eing treated for thiocyanate reco~ery is trea.ed for metal value recovery. ~ickel is also advantageously recovered by crystallization. Crystalli-~ation of nickel from the raffinate ~roduces concentrated S mineral acid which can be recycled to condition the raffina~e ~ro~l the extraction stage for scavenging any dissolved thio-cyanate ~alues.
Thiocyanate values dissolved in th~ raffinate can alter-nat vely be recovered by contacting the rafinate with an lC organic extractant of an amine or a quaternary ammonium com-pound dissolved in a water-irnmiscible organic solvent. The ~mine should be water-insoluble and can be a prin~ary, secondary or terLiary amine. The quaternary a~nonium cornpound should ;
also be water insoluble. Although primary and secondary amine3 extract thiocyanate from the raffinate reasonably well, ter- j tiary amines are more effective in scavenging metal complexing constituents contained in the raffinate solutions.
More specifically, among the s-litable amines are includea x-he~tylamines, x-dodecylamines, didodecylamine, ~ri-x-pro-~0 pylamine, trî-x-butylamines, tri(2-ethlyhexyl)amine, ~ri-isooc~ylamine, tertiary amines which are derivatives of styrene oa~ide such ~s di(2-hydroxy-Z-phenylethyl3 ethylamine and ter-tiary amines which are polyglycolamines, such as tripropylene-glycolamine. The use OL X hereinabove as in the term "x-
__ _ _ The present invention relates to a liquid-liquid extraction ~rocess and, more particularly, to an improved ' method of preventing losses of valuable ions used in liquid organic extraction processes.
~lany processes for utilizing liquid extraction techni-ques in treating process solutions to separate one metal value from another metal value exist. Although such liqùid-liquid extraction processes are highly effective in separa-ting one metal value fro~ another metal value, the loss of expensive reagents to tne raffinate and/or to the stripping solution has made the liquid-liquid extraction techni~ues less attractive economically. Reagent costs associated ~ with the recovery of metal values from both the loaded - 15 extractant and the rafrinate have also made these processes less attractive on a co~mercial basis. Losses of v~lua~le or~anic extractant components and the non-regenerative uses o~her reagents have made liquid extraction processes less com2etitive wlth al,ernative methods for separating ~n and/or recovering metal values from aqueous process solu-~iOI~ S .
.
t2) .. . .
~RIEF SUMMARY OF THE INVENTION
- The present invention relates generally to a process for minimizing losses of thiocyanate ions used in solven~
extraction processes to aqueous process solutions. Mineral acid is added to the aqucous process solution to aepress substantially completely ionization of the thiocyanate and to form hydrogen thiocyanate and the aqueous process solu-tion is contacted with a liquid organic solvent to extract the hydrogen thiocyanate.
In one embodiment, an acidic process solution contain-ing two metal values, one of which is complexible by thio-cyanate ions, is contacted with a liquid organic extractant of hydrogen thiocyanate dissolved in a water-immiscible organic solvent to load the extractant with the complexible metal and to produce a raffinate containing the other metal, the loaded extractant is contacted with a sufficiently con-centrated mineral aci~ to strip the complexible metal there-from without dissolving significant amounts of hydrogen thiocyanate in the mineral acid solution. The complexible metal value is recovered by crystallization which also regenerates a concentrated mineral acid solution for further stripping. The acidity of the raffinate is increased to depress the ionization of any hydrogen thiocyanate dissolved therein, and the raffinate is contacted with the stripped extractant to scavenge the hydrogen thiocyanate. The other metal value is recovered by crystallization which regenerates a concentrated acid solution which is recycled to increase the acidity of further amounts of the raf~inate.
(3) ,;, , ~
More particularly, the invention resides in a process for extracting cobalt from an aqueous process solution contain-ing nickel which comprises extracting cobalt from the aqueous solution by contacting the aqueous solution with an organic extractant of a water-immiscible organic solvent of at least one member selected from the group consisting of ketones, esters and alcohols having hydrogen thiocyanate dissolved therein to produce a nickel-containing raffinate and an organic extractant loaded with cobalt, and contacting the loaded extractant with an aqueous solution of a mineral acid having a concentration of at least about 16 N whereby cobalt is recovered as a salt of the mineral acid and the organic extractant is regenerated with minimal thiocyanate losses.
DESCRIPTION OF THE DRAWING
.
Figure 1 is a flowsheet of a process incorporating the process in accordance with the present invention; and - 3a -~L ~ P r . `J S~ ~J ;-3 ~`igur~ ~ is ~ flowsheet of an alternative embodiment of the pr~sent in~rention.
DET~IL~D ~F~CRIPTION
Th~ process in accordance with the present invention 5 can be employed in any process employing solvent extracti~,n in which thiocyanate complexes are formed to provide the reauisite solubility t~ifferentials. However, the present invention will be described in conjunction with the separa-tion of cobalt from nickel-containing aciQic pr~cess solu-1~ tions by use of liquid organic extractants containing hydrogen thioc~anate. Other examples of metal separation that can be effected by practice of the present invent~on include beryllium from aluminum and hafnium from zirconium.
Nickel process solutions having acid strengths up to a~o~t S normal (N) can be treated by the process in ac~or-dance with the present invention to separate cobalt from the nickel process solution. A typical nonlimiting example of an a~ueous nickel process solution is a leach so~ution having a pH value of about 3.5 and containin~ 40 grams per liter tt~pl) nic~el and between 2 and 20 gpl co~alt.
Cokalt is extracted from the nickel process solutio~
~,y contacting the process solution with an organic extractan~
of hydrogen thiocyanate dissolved in a water-immiscible v~anic solvent. This extraction can be conducted in any appararus that provides good liquid-liquid contact. For e~anple, the process can be conducted in packed columns, p~rforatod plate columns, or a series of mixer-settlersr ~ate~-im~isci~le organic sol~-ents that can be employed i~lclu~e Xetones~ esters and alcohols. Methyl iso~utyl 3~t keto~e is ad~antageously used as it is hi~hly ef icient in (4) in extrac'illg co~al~ thiocyanate complexes from nickel-containin~ aqueous solutions. Another ad~antageous water-immiscible organic solvent is ethyl acetate.
Although it is advantageol~s to employ an organic S extractant of hydrogen thiocyanate dissolved in a water-im~iscihle organic solvent, cobalt can also be extracted from nickel containing process solutions by adding water-soluble ~hiocyanate compounds, such as calcium thiocyanate, sodium thiocyanate, and potassium thiocyanate to the nickel-1~ ccn~aining process solutions to form cobalt thiocyanate complexes in the aqueous phase and then contacting ~he aqueous phase with a water-immiscible organic solvent to extract the cobalt thiocyanate complexes from the aqueous phase in~o ~he organic solvent. This latter embodiment is effective 1~ b~t large amounts of thiocyanate compounds must be adde~ to the aqueous phase to c~mplex the cobalt values. When hydrogen thiocyanate ~s dissol~ed in the organic solvent comp~ratively small quantities of thiocyanate ions are reauired.
As noted above, it is advantageous to incorporate hydro-gen thiocyanate in the orsanic solvent before contacting the nickel process solution with the organic extractant. Hyd~o-gen thiocyanate is incorporate~ in the organic solvent in amounts between about O gpl and about 70Q gpl, advantageously, in amounts between about 100 gpl and about 450 gpl. Organic extractants containing hydrogen thiocyan~te within the fore~oing ranges are highly e~fective in ~xtracting cobalt from nick~l-containing process solutions while minimizing thiocyanate losses to the raffinate.
'~he extraction process ~rodllces a subs~antially cobal.-3~ free ra~finate ard a cobalt-loaded organic extr~ctant.
( ~ ) T~e raffinat2 is treated for nickel recovery, and the cobalt-load~d or~anic ~x~ractant is stripped of its cobalt values t~ regenera~ the organic extractant. AdvantageQusly, a mine~al ~cid is added to the raffinate to increase the 5 C concentration of this solution to~value of at least abou~ 5 N
al~d then the raffinate is contacted with the organic extractant regenerated in the stripping operation to recover any thio-cyanate ions dissolved in the raffinate.
Alternatively, the ra~finate can be trea-ted with a second organic Pxtr~ctant comprising an amine or a quaternary ammonium cor.pound dissolved in a water-immiscible organic solvent to recover any dissolved thiocyanate values, as aescribed more ul y hereinzfter. -The loaded organic extractant is advantageously scrubbed with a weak acid solution, i.e., an aqueous mineral acid 501u-tion having a normality of less than ~bout 5~ Contact of the loade2 organic extractant with weak mineral acid solutions scrubs any nickel contained in the organic extrac-ant thereby insuring that the cobalt product obtai.led from the organic 2U extrac~ant is substantially nickel ~ree. Aci~ scrubbing of the loade~ organic extraction is ef~cctive in removing suffi-cie~t amounts of nickel so that the final cobalt product has a cobalt to nickel ratio of at least about 2000:1. The scrubb-ng solution can be recycled to the nic~el process ~5 solution to return the nickel values to the nicXel circuit.
The scrubbed, loaded extractant is contacted with an aqueous mineral acid solution having a normality greater than about 16. ~dvanta~eously, the loaded extractant is contacted ~7ith sul,uric acid solutions at concentration between about N and about 21 N. Upon contact wi~h concentrated sul~uric acid7 cob~lt is back e~tracted into the sulfuric acid sol~Lion and ~ile organic extractan-t is rec,en~rated for reuse ~) ~ ~ i in ~he extrclctiorl stage Stripping with concentrated aq~e~us solutions of mineral acids is an advantageous feature of the present invention. Stripping with concentrated mineral aciA solutions minimizes losses of thiocyanate to the stripping solution.
Co~alt contained in the stripping solution is advanta-geou,ly recovered by crystallization. For exam~le, cobalt can be crystallized from the stripping solution by increasing the acid concentration thereof to diminish cobalt solubility 1~ or by the combination of increasing the acid concentration whil_ lowering th~ temperature of the solution to again lower cobalt ~olubility. Crystallization can also be accomplished by heatin~ the stripping solution to vaporize water which increases the acid concentrations to the point that cobalt is precipi~ated.
Cr~stallization by hea.ing has the advantage of also vaporizing any organic solvent which can be recovered and recycled to the proces3. Crystallization of cobalt from the stripping solu-tion regenerates a concentrated mineral acid solution which can be recycled to the stripping operation. Thus, the only mineral acid ~hat has to be added to the system is an amount equivalent to that xemove~ by crystallization.
As noted hereinbefore, the raffinate is treated for nic~el recov~ry. Advantageously, sufficient mineral acid is added to the raffinate to increase its acid concentration ^'S to at leæst about ~.5 N, and advantageously between about 4.5 ~T and 14 N. The raffinate with its aci~ content so adjusted is contarted with the regenerated orqanic extractant Irom, the stripping operation whereby any thiocyanate contain-ed in the -affinate is reccvered in the regenerated or~anic 3~ extractant. The treatment of the raffinate with mineral acid ~nd subs~quen~ coniact with the resenerated organic extractant along with the stripping with _oncent~ated ~ineral acids minimizes 1GSS of the metal complexing constituents.
The raffinate after ~.eing treated for thiocyanate reco~ery is trea.ed for metal value recovery. ~ickel is also advantageously recovered by crystallization. Crystalli-~ation of nickel from the raffinate ~roduces concentrated S mineral acid which can be recycled to condition the raffina~e ~ro~l the extraction stage for scavenging any dissolved thio-cyanate ~alues.
Thiocyanate values dissolved in th~ raffinate can alter-nat vely be recovered by contacting the rafinate with an lC organic extractant of an amine or a quaternary ammonium com-pound dissolved in a water-irnmiscible organic solvent. The ~mine should be water-insoluble and can be a prin~ary, secondary or terLiary amine. The quaternary a~nonium cornpound should ;
also be water insoluble. Although primary and secondary amine3 extract thiocyanate from the raffinate reasonably well, ter- j tiary amines are more effective in scavenging metal complexing constituents contained in the raffinate solutions.
More specifically, among the s-litable amines are includea x-he~tylamines, x-dodecylamines, didodecylamine, ~ri-x-pro-~0 pylamine, trî-x-butylamines, tri(2-ethlyhexyl)amine, ~ri-isooc~ylamine, tertiary amines which are derivatives of styrene oa~ide such ~s di(2-hydroxy-Z-phenylethyl3 ethylamine and ter-tiary amines which are polyglycolamines, such as tripropylene-glycolamine. The use OL X hereinabove as in the term "x-
2~ he~tylamines'i is intended to refer to any structural isorners, as l-n-heptvlarnine, 2-n-heptylamine, etc.
Examples of quaterI-ary ammonium compounds that are use-rul in scaven-~ing thiocyar;ate from the raffinate includ~
c~.ialk~l di methyl ammonium chloride in which the two al~
3i~ gr~ups eac~ ha~re a ca~bon chaill lenq~h va-iriny from e;ght to eiyhto--n and a~eraqing about tt~elve and monomethyl trial~yl quatern~ry ammonium chloride in t`'hich each al~yl chaitl e?~ch ;. . ` ' 1 contains bfef~ween eight and ten carbon atoms. The ff~mines or f quaternary a~lonium compounds are f-issolved in a water-im~is~
cible organic solvent. Examples o_ such solvents include - 3 ~ r foJ6~f~e me~hyl isobutyl ketone, benzene, ko'uenc, xylene, water-S immiscible alcohols, mixtures of sucn alcohols with ketones ` or xylene and esthers. The amines or qua.ernary ammonium ~ - . - i compounds are present in the organic solve~t in amounts suffi-cient to insure scavenging of the m-tal complexing constituent from ~he raffinate. In most instances, efficient scavenging ~10 is realized if the organic extractfffnt contains a~fout 20%, by weight, of the amine or the quaternary ammonium compound.
; The organic extractant loaded -ff~ith thiocyanate i8 then ! treated ~or the recovery thereof. The loaded extractant is -ad~antageously treated with a base, such as soda ash or ammonium ~15 hydroxide,-to produce an aqueous thiocyana.e solution. The ~
aqueous thiocyanate solution is reoycled to the stripping~cir cui~ where the aqueous thiocyanate solution and the loaded extrac~ant are contacted whereby thiocyanate in the aqueous phase is transfer~ed to the organic ~hase.~ Advantageously, ~;
~0 the aqueous thiocyanate solution is recycled to the scrub stag2, Y ~ when such a scrubfbfing operation is e.. ployed, and thiocyanate in - the aqueous phase is transferred to ~he organic phaseff. ~ -Referring now to Figure 1 there is disclosed one embo~iment of the present invention. Cobalt confained in nickel process f~S solution 1 is extracted by contacting process solution 1 with an f~ ~ organic extractant which contains b~'ween~about 100 gpl and about 450 gpl hydrogen thiocyanate cissolved in methyl isobutyl f ketone in co~alt extraction stage 2. The produffcts from this ~ f xtraction operation include nic~el-containir.g raffinate 15 and cobalt-loaded extractant 5. The cobalf~-loaded extractant 5 .
(9) ... . . . . ~ . . ....
is scrub~ed o. its nickel content by an a~ueous solution or 5 N sulf~ric acic7, stream 7. The aqueous scrubbed sol.ution
Examples of quaterI-ary ammonium compounds that are use-rul in scaven-~ing thiocyar;ate from the raffinate includ~
c~.ialk~l di methyl ammonium chloride in which the two al~
3i~ gr~ups eac~ ha~re a ca~bon chaill lenq~h va-iriny from e;ght to eiyhto--n and a~eraqing about tt~elve and monomethyl trial~yl quatern~ry ammonium chloride in t`'hich each al~yl chaitl e?~ch ;. . ` ' 1 contains bfef~ween eight and ten carbon atoms. The ff~mines or f quaternary a~lonium compounds are f-issolved in a water-im~is~
cible organic solvent. Examples o_ such solvents include - 3 ~ r foJ6~f~e me~hyl isobutyl ketone, benzene, ko'uenc, xylene, water-S immiscible alcohols, mixtures of sucn alcohols with ketones ` or xylene and esthers. The amines or qua.ernary ammonium ~ - . - i compounds are present in the organic solve~t in amounts suffi-cient to insure scavenging of the m-tal complexing constituent from ~he raffinate. In most instances, efficient scavenging ~10 is realized if the organic extractfffnt contains a~fout 20%, by weight, of the amine or the quaternary ammonium compound.
; The organic extractant loaded -ff~ith thiocyanate i8 then ! treated ~or the recovery thereof. The loaded extractant is -ad~antageously treated with a base, such as soda ash or ammonium ~15 hydroxide,-to produce an aqueous thiocyana.e solution. The ~
aqueous thiocyanate solution is reoycled to the stripping~cir cui~ where the aqueous thiocyanate solution and the loaded extrac~ant are contacted whereby thiocyanate in the aqueous phase is transfer~ed to the organic ~hase.~ Advantageously, ~;
~0 the aqueous thiocyanate solution is recycled to the scrub stag2, Y ~ when such a scrubfbfing operation is e.. ployed, and thiocyanate in - the aqueous phase is transferred to ~he organic phaseff. ~ -Referring now to Figure 1 there is disclosed one embo~iment of the present invention. Cobalt confained in nickel process f~S solution 1 is extracted by contacting process solution 1 with an f~ ~ organic extractant which contains b~'ween~about 100 gpl and about 450 gpl hydrogen thiocyanate cissolved in methyl isobutyl f ketone in co~alt extraction stage 2. The produffcts from this ~ f xtraction operation include nic~el-containir.g raffinate 15 and cobalt-loaded extractant 5. The cobalf~-loaded extractant 5 .
(9) ... . . . . ~ . . ....
is scrub~ed o. its nickel content by an a~ueous solution or 5 N sulf~ric acic7, stream 7. The aqueous scrubbed sol.ution
3 CGntainii~g nic~el is recycled to cobalt extraction stage 2 or is al,ernatively combined wi.th the feed solution 1. The S scrubbed cobalt-loadecl organic extractant 8 is then stripped of its cobalt content in stripping stage 9 by contact with concentrated sulfuric acid. The su~furic acid solution con-.
taining cobalt is treated by crystallizing cobalt in c~balt crystallization stage 11 and the acid generated in stage 11 lC is returned ~o the cobalt strippi.ng stage 9. Stripping of cobalt from the scrubbed cobalt loaded organic extrac~ant 8 ;~
regenerates the organic ex-~ractant 14. Nickel-containing raffinate 15 i.~ conditicned by the addition of sulfuric acid and is then contacted with regenerated organic extractant 14 in thiocyan~t~ scavenging stage 16 .to recover,any thiocyanate ~ontained in nickel-containing raffinate 15. The thus recon-stitute~ organic extractant 4 is recycled cobalt extraction , stage 2. Nickel-containing raffinate lg from which thiocya-nate has been removed is treated to ~rystallize nickel in niclcel crystallization stage 20 and to regenerate 65% sulfuric ~cid- which is recycled to thiocyanate scavenging stage 16.
From the description of this embodiment it is apparent t~.at both acid consumption and thiocyanate losses to the aqueous p~ases are ~.inimized.
1~he use of a second organic extractant comprising an ~nine or quaternary ammonium compound is dissolved in a water- I
imm,iscible orsanic sol~ent is disclosed in Figure 2. ~ic'.~el- ` -and cobalt-containing p~ocess solution 1 is ~ed to cobalt extraction stage 2 ~7here the soll~tion is contacted with an :iC orsanic extractant c,~omprisins h~drocJen thiocyanate dissolvPd i.~ me~hyl i~obuty.~ ketone. The cobalt-loaded organic extract-ant S is trans~err~d to the nickel scrubbing stage 6 where the organic e~tractant is contacted with a 3 ~T sulfuric acid solu- , tion 7. The nickel-containing scrubbing solution ~rom stage 6 '.
is recycled cobalt extraction stage 2. The scrubbed cobalt-loaded organic extractant is stripped of its cobalt content in strip?ins stage 9 by the addition of 55~ suluric acid in stream ~ The resulting cobalt sulfate solution 10 is trea'ed ;.n cobalt crystallization stage 11 to crystallize cobalt as cobalt sulfate 12. Suluric acid resulting from stage 11 is combined wi.h fresh 55~ suluric acid and recycled to cobalt stripping s.a~e 9. Nickel-containing raf~inate 16 from co~alt extr~ction st'-age 2 is treated with an organic extractant of a terti~ry amine dissolved in kerosene to sca~enge any thiocyanate dissolved in ra~.inate 16. Thiocyanate-loaded organic extractant 21 is t~eated with a 1~% ammonium hydroxide solution to regenerate the thiocyanate scavenging organic extractant 18 and to producQ
an ~queous thiocyanate solution 24 which is recycled to ~ nickel scrubbing stage 6. After any thiocyanate is scavenged from the raff~nate 15 nickel is reoovered from the sul~ate solution by conventional tec~n.iques.
. For the purpose of giving those skilled in the art a better understanding o the present invention the following illustrative examples are given:
':~ EXAMEL
A nickel process solution containing 46.9 gpl nick~l and
taining cobalt is treated by crystallizing cobalt in c~balt crystallization stage 11 and the acid generated in stage 11 lC is returned ~o the cobalt strippi.ng stage 9. Stripping of cobalt from the scrubbed cobalt loaded organic extrac~ant 8 ;~
regenerates the organic ex-~ractant 14. Nickel-containing raffinate 15 i.~ conditicned by the addition of sulfuric acid and is then contacted with regenerated organic extractant 14 in thiocyan~t~ scavenging stage 16 .to recover,any thiocyanate ~ontained in nickel-containing raffinate 15. The thus recon-stitute~ organic extractant 4 is recycled cobalt extraction , stage 2. Nickel-containing raffinate lg from which thiocya-nate has been removed is treated to ~rystallize nickel in niclcel crystallization stage 20 and to regenerate 65% sulfuric ~cid- which is recycled to thiocyanate scavenging stage 16.
From the description of this embodiment it is apparent t~.at both acid consumption and thiocyanate losses to the aqueous p~ases are ~.inimized.
1~he use of a second organic extractant comprising an ~nine or quaternary ammonium compound is dissolved in a water- I
imm,iscible orsanic sol~ent is disclosed in Figure 2. ~ic'.~el- ` -and cobalt-containing p~ocess solution 1 is ~ed to cobalt extraction stage 2 ~7here the soll~tion is contacted with an :iC orsanic extractant c,~omprisins h~drocJen thiocyanate dissolvPd i.~ me~hyl i~obuty.~ ketone. The cobalt-loaded organic extract-ant S is trans~err~d to the nickel scrubbing stage 6 where the organic e~tractant is contacted with a 3 ~T sulfuric acid solu- , tion 7. The nickel-containing scrubbing solution ~rom stage 6 '.
is recycled cobalt extraction stage 2. The scrubbed cobalt-loaded organic extractant is stripped of its cobalt content in strip?ins stage 9 by the addition of 55~ suluric acid in stream ~ The resulting cobalt sulfate solution 10 is trea'ed ;.n cobalt crystallization stage 11 to crystallize cobalt as cobalt sulfate 12. Suluric acid resulting from stage 11 is combined wi.h fresh 55~ suluric acid and recycled to cobalt stripping s.a~e 9. Nickel-containing raf~inate 16 from co~alt extr~ction st'-age 2 is treated with an organic extractant of a terti~ry amine dissolved in kerosene to sca~enge any thiocyanate dissolved in ra~.inate 16. Thiocyanate-loaded organic extractant 21 is t~eated with a 1~% ammonium hydroxide solution to regenerate the thiocyanate scavenging organic extractant 18 and to producQ
an ~queous thiocyanate solution 24 which is recycled to ~ nickel scrubbing stage 6. After any thiocyanate is scavenged from the raff~nate 15 nickel is reoovered from the sul~ate solution by conventional tec~n.iques.
. For the purpose of giving those skilled in the art a better understanding o the present invention the following illustrative examples are given:
':~ EXAMEL
A nickel process solution containing 46.9 gpl nick~l and
4.01 g~l cobalt (i.e, a nickel to cokalt ratio of ahout 10:1) was concurrently contacted with an organic e~tractant comprising ~e~hyl .iso~u-t~l ketone in which 150 grams per liter o thiocya-nz~e were dissolved. The volumetric ratio of organic extrac~ant .... . . ..
. .
t~ ~he aqueous ~hase was about 1.4:1. The cobalt content of the nickel-containing solution was lowered to 0.003 gpl. The cobalt-loaded orga~ic extractant containing 3.82 gpl cobalt and 0.2 gpl nic~el was fed to a nickel scrubbing operation in which the loaded extractant was contacted with 5 N sulfuric a~id in a volumetric ratio of organic ~o aqueous of about 10 The nickel scrubbing operation produced a scrubbing solution containing 1.38 gpl nickel and 15.2 grams per liter cobalt, whlch was recycled to the cobalt extraction stage, and a scrubbed orga~ic extractant which contained less than 0.003 gpl nickel and 2.58 gpl cobal~.
T~e organic extractant scr-lbbed of its nickel content was then treated with an aqueous solution of 55.5~ sulfuric acid at a vclumetric ratio of organic to aqueous of about 6:1, The 1~ stripping operation produced a cobalt sulfate solution h~ving co~a~t to nickel ratio greater than 2800:1 and containing a~ou 0~5% gpl thiocyanate~ Cobalt was recovered from the cobalt sulfate solution by crystallization which produce~ a co~centrated sulfuric acid solution containing 3.4 gpl cohalt ~'~ an~ 0.~7 gpl nickel. The concentrated sulfuric acid solution d~ri~ed from the cobalt crystallization stage was recycled to the cobalt stripping operation.
The nickel-containing raffinate from the cobalt extraction sra~e containing 36.5 gpl nickel and 0.009 gpl cobalt was treat-~5 ed in a scavenging stage to reco~er thiocyanate dissolved there-in. The nic~el-containing raffinate was conditioned for thio-cyanate recovery by the addition of 65~ sulfuric acid at a volu~2tric ratio of raffinate to aqueous sulfuric acid solution o about 1.6:1. The acid conditioned raffinate ~a~ then contact~
~0 with the re~enerated organic extractant fro~ t~Le cob~lt s~ripping tl2) ~, . . . . .. . . . . . . .. . . . . . .. .. .. . .. . .. ..... . . . ..
o~eration to recover any thiocyanal:e dissolved in the raffina.e an~ the organic e~tractant containing the recovered thiocyanate is recycled to the cobalt extraction stage.
The nickel-containing raffinate from which the thiocyanate was recovered was then treated fo~ nickel recovery by crystalli-zation. Crystallization of nickel sul~ate from the raffinate ~roduces a 65~ sulfuric acid solution, about 10~ of which was bled off and the remainder recycled to condition the raffi~ate for thiocyanate recovery. The nickel product of the crystalli-lC zation process had a nickel to cobalt ratio of 7700~ . the nickel to cobalt ratio in the product was improved 770 tim~s over t~at in the ~eed material.
~he closed cycles of the cobalt stripping and cobalt crystal-lization operation and the thiocyanate sca~enging and nic~el crystallization cooperate to minimize thiocyanate losses as ~-ell as acid consumption thereby rendering the overall process econo-mically at:~ractive.
XAMPLE II
A nickel process solution containing 63.4 ~pl nickel and 1.62 spl cobalt (a nickel to cobalt`ratio of about 40~ Jas fed to a co~al~ extraction stage where cobalt was extracted witn an organic extractant of 150 gpl thiocyanate dissolved in m2'hyl isoblltyl ketone in a volumetric ra~io of organic-to aqueo~s of about 4:1. The nickel raffinate contained 48.2 gpl nickel, 0.003 gpl cobalt and about 45 gpl nickel, 0.003 gpl cobalt and 45 gpl thiocyanate which raffinate was conveyed to the thiocyanate scavenging operation. The cobalt-load2d extractani contained 0.02 gpl nickel and 0.309 gpl cobalt ~hich was treate~ for cobalt recovery.
~ .
(13) ..... ..
The cobalt-loaded orqanic extractant was initially scrubbed ~i~h 3 N ~ulfuric ~cid at an organic to aqueous ~olumetric ra'io of about 16~1. The aqueous scrub~ing solution containing l.64 t gpl r.ickel and 0.76 gpl cobalt was recycled to the cobalt ex- '~
traction stage.
The scrubbed cobalt-loaded organic extractant was stripped of its cobalt content by contact with an ~queous solution of 55%
sul~uric acid at a volumetric ratio of organic extractant to aqueous phase of about 11:1. In the cobalt stripping-operation, fresh thiocyanate was added to the aqueous phase which was then transferr~d to the organic extractant in order to make up for any thiocyanate ~osses in a circuit.
The cobalt-containing aqueous phase from the stripping ope~a~
tion was treated to crystallize cobalt a~ cobalt sulfate and to generate a 55% fiulfuric acid solution. The regenerated acid together with fresh make up sulfuric acid was recycled to the ~ -cobalt stripping operation. -, The nickel-containing raffinate was initially treated to recover the thiocyanate ions dissolved therein. Thiocyanate ~0 dissolved in the raffinate was recovered by contacting the raff~nate with an organic extractant of a tertiaxy amine dis-solved in kerosene at an organic to aqueous volumetric ratio of about 3:1. This thiocy~nate recovery operation lowered the thiocyanate content of the raffinate solution to 0.05 gpl and provided a nickel-containing solution having a nickel to cobalt ratio o about 11,0~0:1 (i.e. the nickel to cobalt ratio in the product solution was 790 t mes that of the feed solution).
The organic extractant containing the thiocyanate recovered fro~. the rafrinat2 was treated with a 10~ ammonium hydroxide solution at a volumetric ratio of organic to ammonium hydroxide (14) .... .. . . .. . . .. . ..... . . . .. . .... . . .... .. ....
soi~;~ion o a~out 24:1 to prGduce an aqueous thiocyanate solution contai~inS 243 gpl. thiocyanate, 2.66 gpl nickel and 0.016 gpl co~alt which aqueous thiocyanate solution was recycled to the nic~el scrubbing stage whereby substantially all the thiocyanate
. .
t~ ~he aqueous ~hase was about 1.4:1. The cobalt content of the nickel-containing solution was lowered to 0.003 gpl. The cobalt-loaded orga~ic extractant containing 3.82 gpl cobalt and 0.2 gpl nic~el was fed to a nickel scrubbing operation in which the loaded extractant was contacted with 5 N sulfuric a~id in a volumetric ratio of organic ~o aqueous of about 10 The nickel scrubbing operation produced a scrubbing solution containing 1.38 gpl nickel and 15.2 grams per liter cobalt, whlch was recycled to the cobalt extraction stage, and a scrubbed orga~ic extractant which contained less than 0.003 gpl nickel and 2.58 gpl cobal~.
T~e organic extractant scr-lbbed of its nickel content was then treated with an aqueous solution of 55.5~ sulfuric acid at a vclumetric ratio of organic to aqueous of about 6:1, The 1~ stripping operation produced a cobalt sulfate solution h~ving co~a~t to nickel ratio greater than 2800:1 and containing a~ou 0~5% gpl thiocyanate~ Cobalt was recovered from the cobalt sulfate solution by crystallization which produce~ a co~centrated sulfuric acid solution containing 3.4 gpl cohalt ~'~ an~ 0.~7 gpl nickel. The concentrated sulfuric acid solution d~ri~ed from the cobalt crystallization stage was recycled to the cobalt stripping operation.
The nickel-containing raffinate from the cobalt extraction sra~e containing 36.5 gpl nickel and 0.009 gpl cobalt was treat-~5 ed in a scavenging stage to reco~er thiocyanate dissolved there-in. The nic~el-containing raffinate was conditioned for thio-cyanate recovery by the addition of 65~ sulfuric acid at a volu~2tric ratio of raffinate to aqueous sulfuric acid solution o about 1.6:1. The acid conditioned raffinate ~a~ then contact~
~0 with the re~enerated organic extractant fro~ t~Le cob~lt s~ripping tl2) ~, . . . . .. . . . . . . .. . . . . . .. .. .. . .. . .. ..... . . . ..
o~eration to recover any thiocyanal:e dissolved in the raffina.e an~ the organic e~tractant containing the recovered thiocyanate is recycled to the cobalt extraction stage.
The nickel-containing raffinate from which the thiocyanate was recovered was then treated fo~ nickel recovery by crystalli-zation. Crystallization of nickel sul~ate from the raffinate ~roduces a 65~ sulfuric acid solution, about 10~ of which was bled off and the remainder recycled to condition the raffi~ate for thiocyanate recovery. The nickel product of the crystalli-lC zation process had a nickel to cobalt ratio of 7700~ . the nickel to cobalt ratio in the product was improved 770 tim~s over t~at in the ~eed material.
~he closed cycles of the cobalt stripping and cobalt crystal-lization operation and the thiocyanate sca~enging and nic~el crystallization cooperate to minimize thiocyanate losses as ~-ell as acid consumption thereby rendering the overall process econo-mically at:~ractive.
XAMPLE II
A nickel process solution containing 63.4 ~pl nickel and 1.62 spl cobalt (a nickel to cobalt`ratio of about 40~ Jas fed to a co~al~ extraction stage where cobalt was extracted witn an organic extractant of 150 gpl thiocyanate dissolved in m2'hyl isoblltyl ketone in a volumetric ra~io of organic-to aqueo~s of about 4:1. The nickel raffinate contained 48.2 gpl nickel, 0.003 gpl cobalt and about 45 gpl nickel, 0.003 gpl cobalt and 45 gpl thiocyanate which raffinate was conveyed to the thiocyanate scavenging operation. The cobalt-load2d extractani contained 0.02 gpl nickel and 0.309 gpl cobalt ~hich was treate~ for cobalt recovery.
~ .
(13) ..... ..
The cobalt-loaded orqanic extractant was initially scrubbed ~i~h 3 N ~ulfuric ~cid at an organic to aqueous ~olumetric ra'io of about 16~1. The aqueous scrub~ing solution containing l.64 t gpl r.ickel and 0.76 gpl cobalt was recycled to the cobalt ex- '~
traction stage.
The scrubbed cobalt-loaded organic extractant was stripped of its cobalt content by contact with an ~queous solution of 55%
sul~uric acid at a volumetric ratio of organic extractant to aqueous phase of about 11:1. In the cobalt stripping-operation, fresh thiocyanate was added to the aqueous phase which was then transferr~d to the organic extractant in order to make up for any thiocyanate ~osses in a circuit.
The cobalt-containing aqueous phase from the stripping ope~a~
tion was treated to crystallize cobalt a~ cobalt sulfate and to generate a 55% fiulfuric acid solution. The regenerated acid together with fresh make up sulfuric acid was recycled to the ~ -cobalt stripping operation. -, The nickel-containing raffinate was initially treated to recover the thiocyanate ions dissolved therein. Thiocyanate ~0 dissolved in the raffinate was recovered by contacting the raff~nate with an organic extractant of a tertiaxy amine dis-solved in kerosene at an organic to aqueous volumetric ratio of about 3:1. This thiocy~nate recovery operation lowered the thiocyanate content of the raffinate solution to 0.05 gpl and provided a nickel-containing solution having a nickel to cobalt ratio o about 11,0~0:1 (i.e. the nickel to cobalt ratio in the product solution was 790 t mes that of the feed solution).
The organic extractant containing the thiocyanate recovered fro~. the rafrinat2 was treated with a 10~ ammonium hydroxide solution at a volumetric ratio of organic to ammonium hydroxide (14) .... .. . . .. . . .. . ..... . . . .. . .... . . .... .. ....
soi~;~ion o a~out 24:1 to prGduce an aqueous thiocyanate solution contai~inS 243 gpl. thiocyanate, 2.66 gpl nickel and 0.016 gpl co~alt which aqueous thiocyanate solution was recycled to the nic~el scrubbing stage whereby substantially all the thiocyanate
5 recovered ~rom the raffinate was returned to the process.
Again this example demonstrates tha' the use of concentrated sulfuric acid to strip the cobalt from the cobalt-loaded organic extract2nt together with the use of a second organic extractant to recover thiocyanate in the raffinate minimizes losses of expen- ;
1~ sive thiocyanate to the system and the use of sulfuric acid.
Although the present invention has been described in con-j~nction with advantageous embodiments, it is to be understood that modifications and variations may be resorted to without ~.eparting from the principles and scope of the invention, a~
15 tho~e skilled in the art will readily understand Such modi~
cations and variations are considered to be within the purview and SCOp2 of the invention and the appended claims.
(15)
Again this example demonstrates tha' the use of concentrated sulfuric acid to strip the cobalt from the cobalt-loaded organic extract2nt together with the use of a second organic extractant to recover thiocyanate in the raffinate minimizes losses of expen- ;
1~ sive thiocyanate to the system and the use of sulfuric acid.
Although the present invention has been described in con-j~nction with advantageous embodiments, it is to be understood that modifications and variations may be resorted to without ~.eparting from the principles and scope of the invention, a~
15 tho~e skilled in the art will readily understand Such modi~
cations and variations are considered to be within the purview and SCOp2 of the invention and the appended claims.
(15)
Claims (11)
1. A process for extracting cobalt from an aqueous process solution containing nickel which comprises extracting cobalt from the aqueous solution by contacting the aqueous solution with an organic extractant of a water-immiscible organic solvent of at least one member selected from the group consisting of ketones, esters and alcohols having hydrogen thiocyanate dissolved therein to produce a nickel-containing raffinate and an organic extractant loaded with cobalt, and contacting the loaded extractant with an aqueous solution of a mineral acid having a concentration of at least about 16 N whereby cobalt is recovered as a salt of the mineral acid and the organic extractant is regenerated with minimal thiocyanate losses.
2. The process as described in claim 1 wherein cobalt is recovered from the mineral acid solution by crystallization and concentrated mineral acid regenerated during crystalliza-tion is recycled to recover further amounts of cobalt from the loaded extractant.
3. The process as described in claim 1 wherein the cobalt-loaded organic extractant is scrubbed with a mineral acid solu-tion to scrub nickel values that were co-extracted with the cobalt values and the resulting nickel-containing scrub solu-tion is recycled to the cobalt extraction stage.
4. The process as described in claim 3 wherein the mineral acid is sulfuric acid.
5. The process as described in claim 4 wherein the organic solvent is methyl isobutyl ketone.
6. The process as described in claim 3 wherein a mineral acid is added to the nickel-containing raffinate and then the raffinate is contacted with the regenerated organic extractant whereby thiocyanate contained in the raffinate is recovered by the organic extractant.
7. me process as described in claim 6 wherein after the raffinate is contacted with the regenerated organic extractant nickel is recovered from the raffinate by crystallization which pro-duces a concentrated mineral acid solution that is recycled to adjust the acid content of the raffinate before it is contacted with the regenerated organic extractant.
8. The process as described in claim 2 wherein cobalt is crystallized as cobalt sulfate by heating to vaporize water which increases the solution concentration to the point of crystallization and which vaporizes any of the water immiscible solvent dissolved therein which can be recovered for reuse.
9. The process as described in claim 3 wherein the nickel-containing raffinate is contacted with a second organic extract-ant comprising at least one water-immiscible member selected from the group consisting of amines or quaternary ammonium compounds dissolved in a water-immiscible organic solvent to extract thiocyanate from the raffinate into the second organic extractant, the second extractant containing the thiocyanate is treated with an aqueous solution of a base to regenerate the second extractant and to produce an aqueous thiocyanate solution and the aqueous thiocyanate solution is recycled to the cobalt recovery stage whereby thiocyanate in the aqueous phase is transferred to the organic extractant as it is being regenerated.
10. A process for extracting cobalt from an aqueous process solution containing nickel which comprises:
extracting cobalt from the aqueous solution by contacting the aqueous solution with an organic extractant of methyl isobutyl ketone having thiocyanate dissolved therein to produce a nickel-containing raffinate and an organic extractant loaded with cobalt; separating the loaded organic extractant from the nickel-containing raffinate;
scrubbing the cobalt-loaded extractant with a less than about 5 N sulfuric acid solution to extract any nickel coextracted with the cobalt to produce a scrubbed cobalt-loaded extrac-tant and a scrubbing solution containing nickel; recycling the scrubbing solution containing nickel to the cobalt extrac-tion stage; stripping cobalt from the scrubbed cobalt-loaded extractant by containing the extractant with a between about 16 N and about 21 N sulfuric acid solution to regenerate the organic extractant and to produce a cobalt-containing aqueous solution; recovering cobalt from the cobalt containing aqueous solution by crystallizing cobalt sulfate and regenerating a concentrated sulfuric acid solution which is recycled to the cobalt stripping stage; adjusting the acid concentration of the nickel-containing raffinate to between about 4.5 N and about 14 N by adding concentrated sulfuric acid thereto;
contacting the nickel-containing raffinate having the adjusted acid concentration with the regenerated organic extractant to recover thiocyanate contained in the nickel-containing raffinate; recycling the organic extractant con-taining thiocyanate recovered from the nickel-containing raffinate to the cobalt extraction stage; recovering nickel as nickel sulfate from the nickel containing raffinate from which thiocyanate has been recovered by crystallization which produces a concentrated sulfuric acid solution; and recycling the concentrated sulfuric acid solution from the nickel crystallization stage to the nickel-containing raffinate emanating from the cobalt extraction stage to adjust the acid concentration for thiocyanate recovery.
extracting cobalt from the aqueous solution by contacting the aqueous solution with an organic extractant of methyl isobutyl ketone having thiocyanate dissolved therein to produce a nickel-containing raffinate and an organic extractant loaded with cobalt; separating the loaded organic extractant from the nickel-containing raffinate;
scrubbing the cobalt-loaded extractant with a less than about 5 N sulfuric acid solution to extract any nickel coextracted with the cobalt to produce a scrubbed cobalt-loaded extrac-tant and a scrubbing solution containing nickel; recycling the scrubbing solution containing nickel to the cobalt extrac-tion stage; stripping cobalt from the scrubbed cobalt-loaded extractant by containing the extractant with a between about 16 N and about 21 N sulfuric acid solution to regenerate the organic extractant and to produce a cobalt-containing aqueous solution; recovering cobalt from the cobalt containing aqueous solution by crystallizing cobalt sulfate and regenerating a concentrated sulfuric acid solution which is recycled to the cobalt stripping stage; adjusting the acid concentration of the nickel-containing raffinate to between about 4.5 N and about 14 N by adding concentrated sulfuric acid thereto;
contacting the nickel-containing raffinate having the adjusted acid concentration with the regenerated organic extractant to recover thiocyanate contained in the nickel-containing raffinate; recycling the organic extractant con-taining thiocyanate recovered from the nickel-containing raffinate to the cobalt extraction stage; recovering nickel as nickel sulfate from the nickel containing raffinate from which thiocyanate has been recovered by crystallization which produces a concentrated sulfuric acid solution; and recycling the concentrated sulfuric acid solution from the nickel crystallization stage to the nickel-containing raffinate emanating from the cobalt extraction stage to adjust the acid concentration for thiocyanate recovery.
11. A process for extracting cobalt from an aqueous process solution containing nickel which comprises: extract-ing cobalt from the aqueous solution by contacting the aqueous solution with an organic extractant of methyl isobutyl ketone having thiocyanate dissolved therein to produce a nickel-con-taining raffinate and an organic extractant loaded with cobalt;
separating the loaded organic extractant from the nickel-con-taining raffinate; scrubbing the cobalt loaded extractant with a less than about 5 N sulfuric acid solution to extract any nickel coextracted with the cobalt to produce a scrubbed cobalt loaded extractant and a scrubbing solution containing nickel;
recycling the scrubbing solution containing nickel to the cobalt extraction stage; stripping cobalt from the scrubbed cobalt-loaded extractant by contacting the extractant with a between about 16 N and about 21 N sulfuric acid solution to regenerate the organic extractant and to produce a cobalt-containing aqueous solution by crystallizing cobalt sulfate and regenerating a concentrated sulfuric acid solution which is recycled to the cobalt stripping stage; contacting the nickel-containing raffinate with a second organic extractant comprising at least one water-immiscible member selected from the group consisting of amines or quaternary ammonium compounds dissolved in a water-immiscible organic solvent to extract thiocyanate from the raffinate and to produce an aqueous solu-tion from which nickel can be recovered; treating the second organic extractant containing the thiocyanate with an aqueous solution of a base to recover an aqueous thiocyanate solution and to regenerate the second organic extractant; recycling the regenerated second organic extractant to the nickel-containing raffinate emanating from the cobalt extraction stage to recover further amounts of thiocyanate; and recycling the aqueous thiocyanate solution to the scrubbing stage where thiocyanate in the aqueous solution is transferred to the cobalt-loaded organic extractant.
separating the loaded organic extractant from the nickel-con-taining raffinate; scrubbing the cobalt loaded extractant with a less than about 5 N sulfuric acid solution to extract any nickel coextracted with the cobalt to produce a scrubbed cobalt loaded extractant and a scrubbing solution containing nickel;
recycling the scrubbing solution containing nickel to the cobalt extraction stage; stripping cobalt from the scrubbed cobalt-loaded extractant by contacting the extractant with a between about 16 N and about 21 N sulfuric acid solution to regenerate the organic extractant and to produce a cobalt-containing aqueous solution by crystallizing cobalt sulfate and regenerating a concentrated sulfuric acid solution which is recycled to the cobalt stripping stage; contacting the nickel-containing raffinate with a second organic extractant comprising at least one water-immiscible member selected from the group consisting of amines or quaternary ammonium compounds dissolved in a water-immiscible organic solvent to extract thiocyanate from the raffinate and to produce an aqueous solu-tion from which nickel can be recovered; treating the second organic extractant containing the thiocyanate with an aqueous solution of a base to recover an aqueous thiocyanate solution and to regenerate the second organic extractant; recycling the regenerated second organic extractant to the nickel-containing raffinate emanating from the cobalt extraction stage to recover further amounts of thiocyanate; and recycling the aqueous thiocyanate solution to the scrubbing stage where thiocyanate in the aqueous solution is transferred to the cobalt-loaded organic extractant.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US77254677A | 1977-02-28 | 1977-02-28 | |
| US772,546 | 1977-02-28 |
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| Publication Number | Publication Date |
|---|---|
| CA1112460A true CA1112460A (en) | 1981-11-17 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA297,819A Expired CA1112460A (en) | 1977-02-28 | 1978-02-27 | Solvent extraction process |
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| FR (1) | FR2381548A1 (en) |
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| CN113174485A (en) * | 2021-04-29 | 2021-07-27 | 金川集团镍盐有限公司 | Method for deeply removing calcium and manganese in cobalt sulfate solution |
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| CN111302320A (en) * | 2020-02-01 | 2020-06-19 | 复旦大学 | Nano chemical material and its general synthetic method |
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|---|---|---|---|---|
| US2938769A (en) * | 1952-07-31 | 1960-05-31 | Lyle G Overholser | Separation of hafnium from zirconium |
| FR1168497A (en) * | 1957-01-25 | 1958-12-09 | Pechiney | Method of separating zirconium from hafnium |
| US3069231A (en) * | 1960-12-29 | 1962-12-18 | Union Carbide Corp | Method of separating nickel and cobalt compounds and producing salts therefrom |
| FR1343264A (en) * | 1962-12-28 | 1963-11-15 | Beryloy Ltd | Extraction of beryllium using thiocyanate |
| FR2096865B1 (en) * | 1970-07-08 | 1974-05-24 | Nickel Le | |
| JPS5412403B2 (en) * | 1972-02-04 | 1979-05-23 | ||
| CA1021574A (en) * | 1974-03-18 | 1977-11-29 | Jose A. Blanco | Metal extraction process |
| US4008308A (en) * | 1975-12-18 | 1977-02-15 | Union Carbide Corporation | Separation of cobalt from nickel thiocyanates with isophorone |
-
1978
- 1978-02-27 CA CA297,819A patent/CA1112460A/en not_active Expired
- 1978-02-28 FR FR7805754A patent/FR2381548A1/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113174485A (en) * | 2021-04-29 | 2021-07-27 | 金川集团镍盐有限公司 | Method for deeply removing calcium and manganese in cobalt sulfate solution |
Also Published As
| Publication number | Publication date |
|---|---|
| FR2381548A1 (en) | 1978-09-22 |
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