WO1997004140A1

WO1997004140A1 - Hydrometallurical process for the recovery of copper from oxidized metal materials

Info

Publication number: WO1997004140A1
Application number: PCT/ES1996/000147
Authority: WO
Inventors: Francisco José ALGUACIL PRIEGO; Luis Magne Ortega; Aurora Gomez Coedo; Patricio Navarro Donoso; Mª Teresa DORADO LOPEZ; Jaime Simpson Alvarez
Original assignee: Consejo Superior Investigaciones Cientificas (Csic); Universidad De Santiago De Chile
Priority date: 1995-07-14
Filing date: 1996-07-12
Publication date: 1997-02-06

Abstract

Hydrometallurgical process for the recovery of copper from oxidized metal materials through lixiviation with an aqueous solution which contains ammonium ions (which is provided to the system as ammonium hydroxide, ammonium carbonate and/or ammonium chloride), and which provides for the formation of ammoniated copper complexes (II), and removal of the copper from the fertile solution obtained by solvent extraction (using acid agents for the extraction), the lixiviation solution being regenerated by neutralization of the acid produced in the copper extraction with the ammonium of the metal complex.

Description

Title

HYDROMETALURGICAL PROCEDURE FOR THE RECOVERY OF COPPER OF OXIDATED METAL MATERIALS

Technical sector

The present invention falls within the sectors of chemical technology, material technology and metallurgical technology.

State of the art The nature of the operations of obtaining copper by pyrometallurgical methods results in the obtaining of certain secondary products, which are normally considered as waste, and which as the smelting powders are collected at the exit of the gases from the ovens (reverber, converter or "flash").

These powders are considered metallurgical materials since they are fundamentally constituted by oxidized metallic materials (oxides, sulfates, etc.) in which copper is the major metallic element and as such they tend to benefit and / or recirculate in the same smelting processes. However, the high copper content of these materials (20-30% and in some cases up to 70%) together with the presence of other elements, some considered as valuable others as toxic, makes this situation, storage or recycling at Casting process is not desirable and is already sold in many cases until its penalty for the increasingly restrictive environmental regulations.

Given these characteristics, a possible route for the benefit of these metallurgical wastes consists of a hydrometallurgical treatment thereof. In particular using aqueous solutions containing ammonium as a leaching agent with a high selectivity with respect to the copper present in these metallic materials. The process object of the present invention patent follows this path and consists in subjecting these metallurgical residues to a treatment that includes several essential steps. Although a part of these stages, considered in isolation, are known, when properly joined they constitute a new process, allowing the separation and recovery of the copper contained in these materials. The present invention claims, in a particular way, the use of aqueous ammonium ion solutions, as a leaching medium for copper in these metallic materials, by the ease with which this leaching agent can be regenerated.

Description of the invention

The present invention describes a process for the recovery of copper and possibly other metals of interest, from oxidized metallurgical residues, such as copper smelting powders, by leaching with aqueous solutions of ammonium ion (which is supplied to the system as ammonium hydroxide, ammonium carbonate and / or ammonium chloride), which results in the formation of the corresponding copper ammonia complexes and separation of this metal from the fertile solution obtained by a stage of solvent extraction stage with type extraction agents acid (with or without the ability to form chelate compounds). In this extraction stage the acidity generated in the metal extraction process is neutralized by the ammonia released in the reaction itself and the ammonium ion solution is regenerated. The copper that has passed into the organic phase is re-extracted from it using the sulfuric acid obtained in the electrolysis of the metal.

The hydrometallurgical treatment consists of a set of stages that together form a closed circuit. With the first block, solubilization of the copper contained in the metallurgical residue is achieved, in the form of ammoniacal complexes. In the second block the treatment of the fertile solution is carried out, recovering the copper dissolved and the leaching solution regenerated, so the circuit is closed

DETAILED DESCRIPTION OF THE INVENTION In the present invention, not only the leaching effect of the ammonium compounds is used, but also the property of the ammonium cation to dissociate and give the protons necessary for the leaching of the oxidized copper species, especially the oxides, producing at the same time ammonia, which complexes copper:

NH / - NH ₃ + ht [1]

This fact causes that when leaching the metallic material or metallurgical residue to benefit, reactions such as:

CuS0 ₄ + 2NH / → Cu (NHf ₂ + SO ² ^ + 2hT [2]

CuO + 2NH / → Cu (NHf ₂ + H ₂ 0 [3]

In reactions [2] and [3] and to simplify the stoichiometry adjustment, the corresponding reaction has been written as if only the diamine copper complex was formed, when in practice the complexes of general formula Cu (NH _{3) can be formed} ) _n ² \ where n can take the value from 1 to 6 (although in practice it is very difficult to form a complex with n greater than 4).

Once the solubilization of copper from the metallic material is achieved and after conventional filtration treatments, etc., and a specific one that will be discussed below, the copper is separated from the fertile solution by solvent extraction. At this stage, acid-type reactive extraction agents are used as extraction agents.

(that form or not chelate type compounds), presenting in this case the particularity that this operation does not require the addition of a neutralizing agent external to the system, since this operation is carried out by the ammonia attached to the metal.

In the conventional extraction method, the copper extraction reaction would be:

CUj ^* + 2HR _org = CuR _20rg + 2H _ac + [4]

In the method proposed in this invention patent the reaction would be:

CU (NHf _2ac + 2HR _org -CuR _2org + 2NH _3ac + 2H _a / [5]

While with the conventional procedure it becomes necessary to add a neutralizer that supplies the OH- ions necessary to neutralize the protons produced in the reaction, in this process the neutralizer is the ammonia of the copper ammonia complex itself, formed according to the reactions [2] and [3]. The leaching agent is regenerated in the extraction reaction [S] so that it can be used again. In reactions [4] and [5], HR represents the acid extraction agent, also in reaction [S] and to facilitate adjustment thereof the reaction has been written as if the predominant copper ammonia complex was the

Cu (NH ₃ ) _Σ 2+

'3/2

An additional advantage obtained with this process is that due to the neutral-alkaline pH of the solution, iron and other series of metals contained in the starting material remain in the insoluole residue. The sulfate ion that does not adversely affect any of the stages of leaching or solvent extraction can be eliminated at some stage of the process to avoid its possible accumulation, this elimination is easily achieved through the use of calcium oxide or hydroxide:

Cu ² + SO / ^' + 2NH ₄ 0H + Ca (OH) ₂ → CaSO / 2H ₂ 0 + Cu (NHJ ₂ ²⁺ + 20hT [6]

The process object of the present invention is described below, referring to the single figure, which is a simplified flow chart thereof.

The leaching stage (stage I) of the metallurgical waste (S 1) can be carried out in a single stage at temperatures between 15 and 100 ° C, preferably 25 ° C, atmospheric pressure or a pressure lower than S atmospheres, preferably atmospheric pressure, and with a residence time between half an hour and four hours, preferably one hour. Leaching is carried out with an aqueous solution of ammonium ion (DI) (which is supplied to the system as ammonium hydroxide, ammonium carbonate and / or ammonium chloride) and preferably containing a concentration of the attack reagent between 1 and 260 grams thereof per 1000 cm ³ of solution.

The pulp ratio or the concentration of the leaching agent in the attack solution must be adequate to ensure the formation of at least the diaminopropy (II) complex and thus not have an ammonia deficit to neutralize the protons produced in the process of metal extraction (equation [5]). On the other hand, this situation can also be avoided if sulfates are precipitated before the extraction operation, since this precipitation produces ammonia as shown in the reaction [6].

As a result of this leaching operation a solution is obtained

(D2), which essentially contains copper, and a residue (Rl). After a solid-liquid separation, the charged leaching solution passes into a series of stages where copper is recovered and at the same time the attack solution is regenerated, which remains in a position to be used in another leaching operation.

By carrying out leaching with aqueous solutions of ammonium ion, due to their nature, very pure solutions are obtained. This purity refers to elements such as iron, whose solubilization is not desirable since its presence can complicate the subsequent treatment of the leaching solution. Given the important presence of this and other elements in the metallurgical materials to be treated, this characteristic of the process has a great advantage.

Iron, which is usually the most important impurity, when attacked immediately passes to the solid residue. If it is present as iron (II), it dissolves very partially to form the Fe (NH3) n2 + ammoniacal complexes, although they also tend to decompose to form insoluble iron (III) compounds and pass to the solid residue.

The treatment of the leaching solution for the separation and recovery of copper, removal of impurities and regeneration of the attack ammonia solution, is carried out in a series of successive stages, in which conventional techniques such as extraction with solvents The order and use of these stages is not essential and can be varied both as to adapt to the nature, composition and laws of the material to be treated. The present invention process is characterized in that it uses ammonia in some of these stages, facilitating the separation of copper and other impurities by neutralizing the acid that is generated in any of these stages. In the flow chart given in the single figure, stages II, III, IV and V represent one of the possible sequences of separation and recovery of copper, removal of impurities and regeneration of the attack solution. This sequence corresponds to one of the preferred variants for the type of starting material considered in this illustrated description of the process. The solution obtained in the leaching stage is treated to remove the sulfates thereof, recover the copper, remove other possible impurities and regenerate the leaching solution.

The sulfate removal stage (stage II) is done by precipitating as

CaSCy2H ₂ 0 (S6) by the addition of calcium oxide (II), calcium hydroxide (II) or other precipitating agent (D3) of this anion. This stage also compensates for the possible ammonia deficit that may exist in the process and regenerate the leaching solution. From this stage an aqueous solution (D4) would be obtained which would be carried out to a solvent extraction operation.

The solution (D4) resulting from the previous stage (stage II) is treated in a solvent extraction circuit using acid-like extraction agents. In the extraction reaction an acid concentration equivalent to that of the extracted metal is generated, the neutralization of this acid by the ammonia of the metal complex completely displaces the extraction equilibrium, which favors the reaction.

The copper extraction stage (stage III) can be carried out preferably using acidic extraction agents such as oximes (for example the commercial products LIX 860, Acorga PT5050 and MOC-45), oxines (for example the commercial product Kelex 100 ), B-diketones (for example the commercial product LIX

54), alkylphosphoric acids (for example the commercial product DP-8R), alkylphosphonic acids (such as the commercial product PC-88A), alkylphosphinic acids (for example the commercial product Cyanex 272), mono and dithioalkyl phosphic acids (such as commercial products Cyanex 302 and Cyanex 301), etc. LIX is a registered trademark of Henkel Corp., Acorga is a registered trademark of ICI, MOC is a registered trademark of Allied Signal, Kelex is a registered trademark of Sherex,

Cyanex is a registered trademark of American Cyanamid, and DP-8R and PC-88A are registered trade products of Daihachi Chemical. The extraction of copper with these extraction agents is carried out at a temperature between 15 and 45 ° C, a residence time between 5 and 20 minutes and dissolving the extraction agent in an aliphatic and / or aromatic organic diluent, for example the n-dean. The organic phase charged with copper would pass to the re-extraction stage (stage IV) where the copper would be recovered using an acid solution, preferably return electrolyte, although another re-extraction technique could be used. In the flow chart of the single figure, the regenerated organic phase corresponds to (D7), the organic phase charged with copper to (D6), the acid re-extraction solution to (D8) and the charged aqueous solution that goes to recovery of the metal by electrolysis to (D9).

The refining (D5) obtained from the extraction operation, practically free of copper, would be taken to a stage (stage V) where the impurities would be removed and / or other metals of interest would be recovered and the leaching solution (DI) would be regenerated. The number of these stages and their sequence is not essential and would be adapted to the composition of the solution.

Example π ° l

It was based on a metallurgical residue (copper smelting powder) that had the composition, in terms of the most representative metal elements, shown in Table 1.

TABLE 1

10 grams of this material was leached with 1000 cm ³ of an ammonium hydroxide solution (244 g / l NH3). The pulp formed was stirred in a reactor at 25 ° C and atmospheric pressure for two hours. A residue and a solution whose composition is shown in Table 2 were filtered off.

TABLE 2

50 cm ³ of the solution obtained were taken and taken to a thermostated reactor at 20 ° C, to which 50 cm ³ of an organic solution of

LIX 860 at 10% v / v in n-dean. This mixture was stirred for ten minutes, then allowing the two phases to separate. Table 3 shows the compositions of the aqueous and organic phases obtained.

TABLE 3

40 cm ³ of the organic phase charged with copper were taken to a thermostated reactor at 20 ° C and 40 cm ³ of an aqueous solution containing 190 g / l sulfuric acid was added. The mixture was stirred for five minutes, allowing the phases to separate. The composition of these phases is shown in Table 4.

TABLE 4

Example 2

It was split from the metallurgical residue whose composition is shown in Table 1. 10 grams thereof were leached with 1000 cm ³ of an aqueous solution containing 65 g / l of ammonium carbonate. The pulp formed was stirred in a reactor at 20 ° C and atmospheric pressure for one hour. From this operation a residue and a solution were obtained whose composition is shown in Table 5.

TABLE 5

From this solution, 40 cm ³ were taken and taken to a thermostated reactor at 20 ° C, contacting 40 cm ³ of an organic phase of LIX 54 at 10% v / v in kerosene. The mixture was stirred for ten minutes, leaving then the phases were separated. As a result of this operation, a refining was obtained containing, among other metallic elements, 0.02 g / l of copper and pH of 8.6 and an organic phase loaded with 1.96 g / l of this metal.

30 cm ³ of the organic phase charged with copper were taken to a thermostated reactor at 20 ° C and 30 cm ³ of an aqueous solution containing 170 g / l sulfuric acid was added, the mixture was stirred for ten minutes, allowing to separate the phases As a result of this operation, an aqueous phase with 1.96 g / l of copper and an organic phase free of this metal were obtained.

Example No. 3

10 grams of the starting metal material and whose composition is shown in Table 1, were leached in a reactor at 45 ° C with 1000 cm ³ of an ammonium chloride solution, containing 260 g / l of this salt, for four hours . Once this operation was completed, the pulp was filtered, obtaining a residue and a solution whose composition is shown in Table 6.

TABLE 6

40 cm ³ of this aqueous solution were taken to a thermostated reactor at 45 ° C and contacted with 40 cm ³ of an organic solution of Cyanex 302 at 5% v / v in n-decane- The operating time was eight minutes. Once the phases were separated, a refining was obtained whose composition is shown in Table 7 and an organic phase containing 2.12 g / l of copper. TABLE 7

Claims

1. HYDROMETALURGICAL PROCEDURE FOR THE RECOVERY OF COPPER OF OXIDATED METAL MATERIALS, characterized by the leaching of these with aqueous solutions of ammonium ion (supplied to the system as ammonium hydroxide, ammonium carbonate and / or ammonium chloride), which allows the corresponding copper ammonia complexes (II). Copper is separated and recovered from the solution by conventional procedures, essentially solvent extraction (with acid-like extraction agents), the acid produced in the copper extraction is neutralized with ammonia, and the leaching solution is regenerated at the same time .

2. The method according to claim 1, characterized in that the material to be treated can be a mixture of oxidized copper species (oxides, sulfates), even if they are impurified by other metallic or non-metallic elements and / or non-oxidized chemical species (sulphides ).

3. Method according to claims 1 and 2, characterized in that the leaching is carried out between 15 and 100 ° C, a pressure of less than 5 atmospheres and using an aqueous solution of ammonium ion as a leaching agent, the concentration of the ammonia attack agent being included in the same between 1 and 260 g / l.

Method according to claims 1, 2, and 3, characterized in that the separation and recovery of copper from the leaching solution is carried out by solvent extraction (using acid-type extraction agents).

5. Method according to claims 1, 2, 3 and 4 characterized in that in the treatment of the solution obtained in the leaching for separation and Recovery of dissolved copper is used ammonia to neutralize the acid that is generated in the separation of this metal.

Method according to claims 1, 2, 3, 4, and 5, characterized in that it allows the inclusion of additional and / or intermediate stages, aimed at the recovery of copper, the recovery of other metallic species present in the material of starting and regeneration of the leaching solution.