DE2615287C2 - Process for the processing of complex non-ferrous metal-containing solutions by solvent extraction and recovery of the valuable carriers contained therein - Google Patents

Description

The invention relates to a multi-stage process for processing non-ferrous metals, in particular copper and zinc-containing solutions of any origin, composition and concentration ratio of the individual non-ferrous metals by solvent extraction, whereby the main components, especially copper and zinc, can be obtained in the form of highly pure end products.

The inventive method is based on Use of a liquid cation exchanger, which is different from the non-ferrous metal cations Has bond strength, as well as the fact that at least one of the invention to be used Solutions is ammoniacal

It is known that in recent times hydrometallurgical processes have been compared to purely pyrometallurgical processes are becoming increasingly important. The reasons for this are once in the need for reduction environmental pollution and, on the other hand, the need to smelt ever poorer ores. aside from that more and more metallurgical intermediate products

te and return materials to NE metal production be included.

Hydrometallurgical processes are often carried out in combination with pyrometallurgical digestion process by this one solvent (lauryl> confining) level out downstream, and the thus obtained complex, often impure, nonferrous metallha ^t! Ge solution in a series of cementation and / or processing processes on the valuable carriers contained therein. The already classic way of processing lye ι ο chlorinated roasted gravel burns is an example of this procedure. A similar combination of processes is the roasting of sulphidic ore concentrates. The roasted product obtained is a non-ferrous metal sulphate mixture, which is also leached with acid. As above, the valuable metals are obtained from the solution by cementation and / or precipitation. As a result of the low selectivity of these separation operations, the non-ferrous metal products obtained, e.g. B. cement copper, zinc hydroxide, cobalt hydroxide, etc., which are still impure and usually require subsequent cleaning. This can consist of fire refining, pressure dechlorination, electro refining or a reprecipitation process.

The basic metallurgical operations listed above have been varied in many ways. It was proposed to pretreat the lye mechanically (z. B. DT-OS 20 42 609) or under To unlock pressure (e.g. DT-AS 19 47 535; Erzi etall X [1957], p. 158 ff .; Journal of Metals [1959], pp. 836 ff.). The use of mineral acids other than sulfuric acid, e.g. B. nitric acid (DT-AS 11 89 720), was? " suggested as well as that of ferric chloride (e.g. DT-OS 20 30 503) or acidic copper sulfate solutions (e.g. DT-OS 22 07 382) as a leaching agent. Summarizing representations of the developments in the Non-ferrous metallurgy are e.g. in E / MJ (1972), p. 173 ff, E / MJ (1975), p. 133 ff, the theoretical fundamentals der Leachung in "Metallwissenschaft und Technik" (1970), p. 1074 ff. given. All procedure is in common that the resulting solutions are acidic and always have certain concentrations of dissolved iron contain, which is very disadvantageous for further processing on valuable metals.

Since cheap ammonia has become available, there has been an effort to prevent iron from going into solution also prevent this solvent from being used. One makes of the property of ammonia Use, practically almost all valuable metals (except gold), but not worthless accompanying metals, in particular iron, manganese, lead, to dissolve in the form of cationic amine complexes. Also the whole pace remains undissolved in contrast to acidic dissolution, in which z. B. silica for colloidal Tends to dissolve and then leads to filtration difficulties.

The ammoniacal ore leaching is described in "Austral Inst, of Mining and Metallurgy", Adelaide (197I) ₁ p. 1 ff .; DT-OS 21 56 940; Canad. Mining (1974), p. 62 ff .; DT-OS 23 62 693 and in Inst, of Mining (1974), pp. C 14 ff. With the addition of air or oxygen, non-ammoniacal solution and non-ferrous metals and alloys can also be dissolved in good yield in a good yield: US 29 12 305, DT-OS 23 40 399 et al. The further processing of these solutions will then be discussed in connection with the improvement of the hydrometallic treatment of the acidic solutions.

With the development of ion exchangers, initially in solid form, hydrometallurgy received the Ability to avoid many of the previous disadvantages of conventional cutting operations. So Ion exchangers cause a much sharper separation of the non-ferrous metals and thus lead to purer ones End products. In addition, a number of complex solid / liquid separation operations (separation of Cementates and felled sludge) of the classic process steps. In contrast, the soon became apparent economic disadvantage of solid exchangers that require an extractant for a complete reaction cycle the metal to be recovered (usually a mineral acid) and a regenerant for the resin (e.g. a lye) and their lifespan is limited, especially in concentrated solutions were therefore only used for very valuable metals, e.g. B. Precious metals, lanthanides, uranium, used and came for non-ferrous heavy metals not considered

The development of liquid extractants also opened up for the extraction of these common metals economically interesting opportunities. A distinction is made between the liquid extractants in three main types of increasing bond strength and selectivity:

a) Non-polar solvents that have purely physical Extract distribution equilibria of neutral molecules,

b) Ion exchangers in the narrower sense, which are either cationic (type organophosphoric acids) or exchange anionic (type aliphatic amines, quaternary ammonium compounds) and

c) chelating agents of the 1,2-diketone type, hydroxyoxime and hydroxyquinolines.

The latter are characterized by their combined ion and coordination bond particularly high selectivity. In the meantime, the properties and application of the exchangers according to b) and c) described in various ways (see ISEC Conference, Lyon 1974, p. 2817 ff .; technical communications Krupp works, 32, p. 29 ff .; Hydrometallurgy 1 (1975/76), p. 6 ff .; Neue Hütte 20 (1975), p. 181 ff .; Anal. Chim. Acta 48 (1969), pp. 107 ff; Chem.-Ing.-Techn., 45 (1973), p. 154 ff .; ISEC conference, Lyon 1974, p. 2837 and p. 699 ff.). The first commercial plant for copper extraction on the basis of ion exchange was put into operation in 1969 in Bluebird, Miami, Ariz., USA (see e.g. E / MJ [1975], p. 101 ff.).

It is also possible, by taking suitable measures, to separate different metals in the organic phase or during re-extraction from the same (elution). Here you turn preferably different ion exchangers one after the other, which the different metal ions different bind tightly (see e.g. US 38 67 506; DT-OS 23 20 880; ISEC Conference, Lyon 1974, p. 829 ff. and p. 669 ff.). These methods are preferred for separating cobalt and nickel. One Another possibility is that the metal-laden, organic phase with a finely ground one Brings complex ore into contact, with more strongly bound metals dissolved out of the solid and for this, more weakly bound ones are released from the organic phase (see e.g. DT-OS 24 27 132; Russ.-Pat. 3 52 955).

Possibilities for separating non-ferrous metals have also been shown in ammoniacal solutions. So US 28 05 918 describes the possibility of a complex, zinc and copper containing, ammonia-

tables Ammonkarbonatlösung preferably zinc excrete by reacting ammonia and carbon dioxide so far overcooked, as long as a substantially copper-free zinc carbonate precipitates. Complete purity of the precipitated zinc product or complete> extraction of the zinc is not possible in this way. According to DT-OS 24 34 949, a specific separation of the cobalt from other amine-forming cations, z. B. nickel, achieved in the ammoniacal phase by contacting the complex amine solution with a chelating ion exchanger and eluting all ions except cobalt with a fresh, metal-free, concentrated NHj / Co2 solution from the loaded organic phase. In a Canadian publication, CIM Bulletin, Extraction Metallurgy Div., Is

_j "" ui; "ni; .a.

ivi 3i ~ nnt.um.ll

Extraction and separation of copper, nickel, zinc and cobalt from ammoniacal solution described. the Separation makes use of the fact that the so-called non-ferrous metals in the chelating exchanger are bound differently and thus by setting defined pH values with sulfuric acid can be eluted separately in stages. The method requires a correspondingly large number of elution stages and also leads - since the 2s Elution pH values are very close to one another - to mixed metal phases that are recirculated or separately need to be worked up.

In a further development of the hydrometallurgical processes described above, a process for working up complex, non-ferrous metal-containing, in particular Zn and Cu-containing solutions, has now been found which does not have the above-mentioned deficiencies. The solutions can also contain other non-ferrous metals in any combination and any concentration. They come from the dissolution of non-ferrous metal-containing, predominantly Cu and Zn-containing ores, metallurgical intermediate products, e.g. B. roasted material, and return materials from the non-ferrous metal production and are referred to in the process scheme as "input materials" (1), which are partly an ammoniacal dissolution (2a), partly an acidic dissolution (2b) .

The method is based on a combination of solvent extraction processes in common units, e.g. B. mixer-settler units and / or exchange columns, as well as the use of a new type of liquid, chelating cation exchanger (solvent I), which has a capacity that is substantially different from zero for all amine-forming non-ferrous metal cations and different bond strengths for the individual cations having. Such exchangers are currently still under development, but will soon also be available in commercial quantities . The method according to the invention is characterized by an almost unlimited flexibility with regard to the starting materials and a number of other advantages, which will be discussed further below.

The process according to the invention is characterized in that , in a multistage process, an aqueous, ammoniacal, ammonium salt-containing, preferably amine-carbonate-containing solution, the amine-forming cations, e.g. B. copper, zinc, cadmium, nickel, cobalt 11. a, as well as anions such as chloride, sulfate, arsenate, etc., in any concentrations and concentration ratios, bring in excess with a liquid cation exchanger (solvent I) in contacti [extraction ( 3) \ whereby the amine-forming cations are converted into the organic phase according to their different bond strengths, while the non-amine-forming cations, ζ. Β Alkali metals, calcium, magnesium, iron, aluminum, etc., as well as all anions remain in the aqueous phase (claim la).

It is further characterized in that the loaded organic phase with a second, acidic aqueous solution which also contains the ions mentioned in a) in any concentrations and concentration ratios contains, and their pH value between that of the beginning precipitation of the contained therein Cations as oxy salts as the upper limit and that of the beginning Meiaüeluierung from the organic Phase as the lower limit, i.e. H. preferably between pH 1 and 3, brings [Cu / Zn exchange (4)], taking into account the proportions between the second, acidic, aqueous solution and the organic Phase so selected that by the amount of copper present in the aqueous solution, which from Cation exchanger is most firmly fixed, all less firmly fixed cations are eluted and into the aqueous phase are transferred (claim 1 b).

Ice is further characterized in that the copper-bearing organic phase is treated with acid, e.g. B. the sulfuric acid back electrolyte from a copper reduction electrolysis, eluted exhaustively [copper elution, solvent I (5) J where the ion exchanger is regenerated, and the high-purity copper sulfate solution obtained in this way is returned to the copper reducing electrolysis (6) supplies, wherein the copper is obtained in the form of Kaihoden (claim 1 c).

Finally, it is characterized in that the ion exchanger is returned to the process stage [extraction (3)], the H ⁴ ions of the exchanger and the OH ions of the ammoniacal solution inevitably forming water in a stoichiometric ratio and the exchanger again is loaded with amine-forming cations of the aqueous ammoniacal, ammonium salt-containing solution in accordance with the first process step (claim Id).

In a further embodiment of the process according to the invention, the aqueous solution running off from the second process step (claim 1 b) is brought along a second, only for copper specific cation exchanger (Solvens II) in contact, whereby the all residual copper is extracted from the running aqueous solution [Cu residual extraction, solvent II

The elution of the copper from the two cation exchangers is expediently carried out with the sulfuric acid back electrolyte of the copper electrolysis in such a way that the more strongly binding, copper-specific second exchanger (solvent II) is first eluted with the strongly acidic back electrolyte [Cu-Elution, Solvens II ( 8)] and then this solution, which now has a higher copper content and is less acidic, is used to elute the copper from the first cation exchanger (solvent I) while obtaining a high copper content, weakly acidic copper electrolyte

The amount of water that runs off after the extraction with the second copper-specific cation exchanger The solution contains all of the zinc from the two preceding solutions, but only traces of copper. she

also contains the anions of the acidic solution, d. i. preferably sulfate and chloride ions, as well as the all other non-ferrous metals that may be present in the starting materials, e.g. B. cadmium, nickel, cobalt. You can of these by known methods, for. B. by zinc dust cementation or a so-called sulphidating cementation with Zn "+ S" can be exempted. From the purified solution can be known in Way, possibly after adding sodium chloride, pure Glauber's salt crystallize out and finally the κ Obtain zinc through precipitation as hydroxide, carbonate or sulfide.

As emphasized at the outset, the method according to the invention is not subject to any restrictions with regard to the Composition of the raw materials for the two lye syrups. The application of an arrsrricrsiaküschen The medium in the first extraction circuit only causes a metal extraction without a pH shift and thus a complete absorption of the non-ferrous metals by the organic phase. It is straightforward possible to obtain both solutions from one and the same Zn- and Cu-containing starting material. It is only to note that at the point of Cu = ^ = Zn exchange in the (first) organic phase about just as much zinc - coming from the ammoniacal solution - is offered as copper from the acidic solution is to be extracted. Both are exchanged in a stoichiometric ratio of 1: 1. Is the If the amount of zinc is much smaller, there is a risk of Cu »breakthrough« into the draining, aqueous zinc salt solution. If it is larger, zinc is carried over into the copper electrolyte as an impurity. This condition is easy to meet, as it is always possible, e.g. B. with zinc deficiency part of the zinc end product in the ammoniacal dissolution, with a copper deficiency part of the copper electrolyte in the acidic solution traced back. For economic reasons it is expedient, preferably for ammoniacal leaching Zinc-rich, low-copper and, in acidic leaching, preferably copper-rich, low-zinc non-ferrous metals To use raw materials.

The method according to the invention offers a number of convincing advantages. The high flexibility in the choice of starting materials has already been pointed out. Second, the process does not require any stoichiometrically proportional auxiliary or operating materials, since all chemicals (organic phases, ammonia, carbon dioxide) are conducted in closed cycles, ie only serve as a means of transport. A suitable precipitant, e.g. B. lime or soda required. Thirdly, thanks to the closed loops, the process is environmentally friendly. Finally, fourthly, the method can be largely automated or process computer-controlled, since all stages are inevitably connected in series and, again with the exception of zinc precipitation, all run in the liquid phase. In this way, the personnel expenditure can be reduced to a minimum.

It must then be emphasized again that the inventive method to the Availability of a liquid cation exchanger which has the following special properties having:

a) Strict selectivity between accepted cations and rejected anions,

b) a loading capacity for all amine-forming cations in the ammoniacal medium, which is given by the molecular structure or the type of bond (chelate bond) and is essentially different from zero,

c) a defined, sufficiently different bond strength (B) for the individual cations, whereby in each case flc _u > Bz _n must be,

d) no loading capacity or binding strength for cations whose normal potential is less noble than that is from zinc.

The copper-specific cation exchanger required in the second organic cycle has been around since available in commercial quantities for a long time.

The following examples, taken from a pilot plant, are intended to illustrate the process according to the invention explain without restricting it to this.

example 1
Copper-zinc exchange

a) From the ammoniacal dissolution (2a) (of the flow diagram) of a zinc-rich mixture of recycling materials, a solution of the following composition was available:

Zn Cu Cd Pb Fe As SiO:

37.5 5.76 0.15 0.01 0.45 0.45 <0.1 g / l

This solution was fed to a fully automatic, continuously operating small pilot plant (bench-scale scale), consisting of a total of 16 mixer-Scttlcr units connected in series. In the four-stage extraction (3), all of the copper and cadmium, by far the largest amount of zinc and part of the lead were absorbed by solvent I. The other substances were not extracted and ran back into the dissolution stage (2a) with the ammoniacal solution. The organic phase to be fed to the copper-zinc exchange stage (4) had the following composition:

Cu
2.61

CD
0.13

Pb

n. b. g / l

The solvent I contained a 15% concentration of the actual active ingredient, dissolved in an aromatic mixture.

b) From the sulphurizing roasting of a mixed flotation concentrate with subsequent leaching (2b) and caustic cleaning, a sulfuric acid solution of the following composition was available:

Cu
61.0

CD
nb

Fe
0.14

Mn
0.02

SiCb
0.18 g / l

In a two-step copper-zinc exchange stage (4), organic (O) stock solution and aqueous / acid (A) merged The O. A volume ratio was 10: 1.85 l / h and was by repeated recirculation of the aqueous phase to the O .: Λ ratio = 1: 1 necessary for optimal settling behavior (i.e. minimal training) The solutions draining from the first copper-zinc exchange stage have the following composition:

Organic phase aqueous phase pH 2.90 (10 l / h) (1.85 l / h)

Zn
Cu

0.40
13.84

100.7
0.32 g / l

In a second stage, the organic phase was subjected to post-purification with a small amount of copper-repelling electrolyte in a volume ratio of O: A ι o = 10: 0.17 l / h.

Composition of the incoming and outgoing solutions:

Organic phase
(10! / H)

Aqueous phase
(0.17 l / h)

Incoming solutions

Zn 0.40

Cu 13.84

0.58
79.0 g / l

10

Organic phase
(10 l / h)

Aqueous phase
(0.17 l / h)

Expiring solutions

Zn
Cu

0.01
14.25

23.5
56.7 g / l

The organic phase was fed to the copper elution (5), the aqueous phase to the incoming acidic feed solution (2b). «.

Example 2
Electrolyte recovery

The organic phase of a chelating, cation-specific liquid exchanger contained after Passing through a multi-stage extraction and exchange process according to Example 1, the following contents:

Cu
14.25

Zn
0.01

Fe
0.004

Pb Co Ni Mn S1O2

<0.001 <0.001 <0.001 zero 0.015 g / l

This phase was brought into contact in a two-stage copper elution (5) with the back electrolyte ("weak electrolyte") of a reduction electrolysis (6) operated ^{at 300 Amp / m 2} in a phase ratio of O: A = 10: 2.59 l / h. The back electrolyte contained 20.3 g / l Cu ²⁺ and 92.5 g / l free acid (f. S. behaves as sulfuric acid).

After the elution (5), the two solutions running off had the following composition.

Organic aqueous phase phase

(10 l / h)

(2.59 l / h = strong electrolyte)

Cu + Zn 0.01

free acid -

75.3
7.7 g / l

The organic phase was returned to the extraction (3) of the ammoniacal solution. The one in the Reduction electrolysis (6) fed in the strong electrolyte had the following composition:

Cu F. S. Zn Fe Pb Mn Co Ni Al Mg Ca S1O2 Cl

75.3 7.7 0.038 0.012 0.002 zero 0.001 0.001 0.012 0.001 0.02 0.04 0.029 g / 1

B e i s ρ i e 1 3

Second exchange circuit (ultra-fine cleaning)

The running from a multi-stage solvent extraction process according to Examples 1 and 2, aqueous In addition to the main component zinc, phase also contained small amounts of from the leading solutions native copper. According to Example 1b, this concentration was 032 g / l Cu in addition to 100.7 g / l Zn in one pH value of 230. To remove this residual copper the aqueous phase was brought into contact with a second solvent II. This solvent II is highly copper-specific, So, in contrast to the solvent I described in Examples 1 and 2, does not take any significant concentrations of other cations, especially no zinc.

The copper-specific exchanger is used in the form of a 20% solution in kerosene

The aqueous solution running off from the copper-zinc exchange (4) was brought into contact with such an organic phase in the phase ratio O: A = 1: 3.7 l / h three-stage copper residual extraction stage (7) the following composition:

Organic phase Residual copper extraction (7) Watery phase (Wh) below 0.001
0.6 (3.7 l / h) Intake Residual copper extraction (7) Zn
Cu
pH 0.005
1.75 100.7
0.32
2 ^ 0 g / l sequence Zn
Cu
pH 100.7
0.005
2.00 g / i

The practically copper-free zinc sulphate solution was further processed for sulphate, e.g. B. in the form of Sodium sulfate, and zinc the organic phase of the copper elution (8) with the strongly acidic back electrolyte fed to the copper reduction electrolysis. That regenerated into the H + form during elution (8) Extracting agent runs back into the copper residual extraction stage (7).

1 BIaU drawings

Claims (5)

Patent claims: 1. Process for the processing of complex, non-ferrous metal-containing, in particular those containing Zn and Cu, using solutions by solvent extraction known units, e.g. B. mixer-settler units and / or exchanger columns, as well as under Use of liquid chelating cation exchangers, at least one of which is ι ο The loading capacity for zinc is significantly different from zero, and there is also a different bond strength for all amine-forming cations, on the other hand has no loading capacity for anions, and extraction of the non-ferrous metals dissolved therein, characterized in that one in a multi-stage process a) an aqueous ammoniacal, ammonium salt-containing, preferably ammonium carbonate-containing solution containing amine-forming cations, e.g. B. Copper, zinc, cadmium, nickel, cobalt and others, as well as anions, e.g. B. chloride, sulfate, arsenate i.a., in any concentrations and concentration ratios contains, with a liquid cation exchanger of the type described above Kind in excess brings into contact, with the amine-forming cations after Depending on their different bond strengths, transferred into the organic phase while the non-amine-forming cations, e.g. B. alkali metals, calcium, magnesium, Iron, aluminum, etc., as well as all anions remain in the aqueous phase, b) the loaded organic phase with a second, acidic, aqueous solution, also üie the ions mentioned in a) in any concentrations and concentration ratios contains, and its pH value between that of the beginning precipitation of the cations contained therein as oxy salts as the upper Limit and that of the beginning metal elution from the organic phase as the lower Limit, d. H. preferably between pH 1 and 3, is brought into contact, wherein the Quantities between the second, acidic, aqueous solution and the organic one Phase so selected that by the amount of copper present in the aqueous solution, which is most firmly fixed by the cation exchanger, all less firmly fixed Cations are eluted and transferred into the aqueous phase, c) the copper-bearing organic phase with acid, z. B. the sulfuric acid back electrolyte from a copper reduction electrolysis, exhaustive eluted, the ion exchanger being regenerated, and the thus obtained high-purity copper sulfite solution again from copper reduction electrolysis supplies, whereby the ho copper is obtained in the form of cathodes, and finally d) returns the ion exchanger to process stage a) again, with the H + ions of the exchanger and the OH - ions of the (> s ammoniacal solution is inevitably formed in a stoichiometric ratio of water and the exchanger again with amine-forming cations of the aqueous ammoniacal, Monon salt-containing solution according to process step a) is loaded. 2. The method according to claim J, characterized in that that the draining from process step b) aqueous solution with a second Brings cation exchanger, which, in contrast to the former, is copper-specific, into contact, whereby all of the residual copper is extracted from the draining aqueous solution. 3. Process according to Claims 1 and 2, characterized in that the elution of the Copper with the sulfuric acid back electrolyte of the copper reduction electrolysis in the way assumes that you first the stronger binding exchanger according to claim 2 with the strong acidic back electrolyte eluted and then this now more strongly Cu-containing, less acidic Solution of the copper regulation according to claim Ic) to complete the copper elution with recovery of a high copper content, weakly acidic copper electrolyte with the according to claim Ib) brings accumulating Cu-containing organic phase into contact. 4. The method according to claims 1 and 2, characterized in that from the Exchanger process after process step Ib) running, aqueous solution in a known manner processed on the remaining non-ferrous metals contained therein, z. B. by zinc dust cementation of Cadmium, nickel, cobalt or by sulphiding cementation of these metals with Zn + S ° subsequent crystallization of Glauber's salt after sufficient addition of rock salt for Removal of the sulfate ions and subsequent precipitation of the zinc as hydroxide, carbonate or Sulfide. 5. Process according to claims 1-4, characterized in that one is used for the starting solutions of the process according to the invention in ammoniacal leaching, preferably zinc-rich, low-copper and in acid leaching, preferably copper-rich, low-zinc non-ferrous metal-containing raw materials begins.