JP3386516B2 - Method for preventing the formation of alkali-based double salts with jarosite and ammonium - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to a method for preventing the formation of jarosite and ammonium and alkali-based double salts in the solvent extraction of acidic leaching processes in which useful metals are separated. In this method, the organic leaching solution is neutralized with ammonium or alkali salts in order to improve the extraction yield, prior to the separation of the useful metals. In the pre-extraction step after neutralization, the extraction liquid is contacted with an aqueous solution containing a metal, and in this pre-extraction, ammonium or alkali ions contained in the extraction solution are replaced. Therefore, said ions are removed from the solvent used for the extraction prior to the separation of the useful metals in the main solvent extraction step.

[0002]

BACKGROUND OF THE INVENTION Iron processing is important when metallurgically processing concentrates and ores. In particular, the behavior of iron is particularly important when and where the treatment is based on a combination of leaching and smelting. One of the characteristics of iron is that in the trivalent state, it forms an alkaline double salt and becomes a composition of D [Fe3 (SO4) 2 (OH) 6]. In these so-called jarosite compounds, D can be an alkali metal such as sodium or potassium, or it can be ammonium.

The jarosite compound is formed from an acidic solution containing trivalent iron and ammonium, sodium or potassium. Jarosite is mainly formed within the pH range of 0.5 to 5.0. Higher temperatures promote this formation. Jarosite is easily formed in the range of 60 to 220 ° C. The higher the temperature, the lower the pH forming jarosite.

In the leaching-based zinc processing method,
It is common to utilize jarosite formation when removing iron from zinc-containing solutions. Conversely, the present invention relates to a method of avoiding the formation of jarosite, another double salt of ammonium or alkali. One of these methods
One is a method for producing nickel, cobalt or copper. The feedstock can be an ore, a concentrate, or an intermediate obtained from the smelting of a concentrate or other similar metal-containing material.

The method in question involves processing steps performed at temperatures above room temperature. These steps are performed at 60 ° C and above at 0.5
It is an atmospheric pressure or pressure leaching process that is performed by containing ~ 85% iron. Within the above treatment steps, iron may also be removed from the treatment solution obtained from the leaching step if the method of application is the usual hydrolysis carried out in the temperature range (60-220 ° C.).

In the above case, the formation of jarosite is unavoidable if the method in question requires the addition of ammonium or alkali containing materials. Such materials are, for example, ammonium or sodium, which are necessary for adjusting the pH value. These are necessary in leaching and iron removal to enhance the clarification of the solution, which is done at higher pH values. For example, in the nickel treatment process, the problem is primarily the removal of zinc, copper and cobalt. In such a case, an ammonium double salt such as nickel ammonium sulfate may cause a crystallization problem and be formed.

Previously, the formation of double salts with jarosite
Was not as problematic as it is today . With the growing need for environmental protection, that need is now a limiting factor in this extraction process. When ammonium is used for neutralization, for example in a process of the type shown in FIG. 1, the formation of ammonium jarosite generates nitrogen in the evolved form of NOX. Under the processing conditions used here, the formation of jarosite cannot be prevented in the leaching step and the iron removal step. The unavoidable consequence is that the leaching residue in these cases contains jarosite.

The above jarosite is decomposed, and in that case, energy is consumed in the next processing step, which is smelting. Therefore, the formation of jarosite effectively reduces costs. In a similar manner, iron precipitation consumes energy in the smelting process, while in the smelting process, to a high extent, it binds the iron to the inert slag and at the same time stores the finely divided iron precipitate. Eliminate related problems. Alkali metals, conversely, are traditionally undesirable materials in smelting.

[0009]

In the [0008] present invention, ammonium or sodium, may be used herein to facilitate the solution clarified, ammonium, sodium or potassium, by preventing contact with the solution circulation , Solvent extraction, avoiding the formation of jarosite or ammonium and alkali-based double salts.

[0010]

According to the method of the present invention,
Prior to the separation of the main useful metals by solvent extraction, the organic extraction solution is neutralized with ammonium or an alkali salt, after which the extraction solution is led to pre-extraction and the extraction solution is
Contact with an aqueous solution containing a metal as an exchange ion, the metal in this pre-extraction step replaces the ammonium or alkali metal ion contained in the extraction solution, and an ammonium or alkali-based double salt is formed in the leaching step. And the extraction solution is guided to the main extract in contact with the aqueous solution containing the useful metal, during the solvent extraction process belonging to the acidic leaching process step for selectively separating the useful metal. A method of preventing the formation of jarosite and ammonium and alkali-based double salts in.

The present invention employs ammonium or sodium to facilitate solution clarification, but during the solvent extraction by preventing ammonium, sodium, or potassium from approaching the solution circulation,
It relates to a method of avoiding the formation of jarosite or ammonium and alkali-based double salts. The extraction solution obtained from the circulation of the extraction treatment is neutralized with ammonium or an alkali salt, but when separating useful metals, ammonium or alkali ions are transferred into an aqueous solution , so to speak, in an extraction solution with exchange ions. Replaced; a pre-extraction step is used to prevent the introduction of the iron into the main extraction circuit.

It is essential that at least one of the useful metals to be separated in the solvent extraction step is more strongly extracted than the exchanged ions. If ammonium and alkali ions are removed from the solution, higher temperatures can be used to enhance and enhance leaching, and smelting further recovers one of the metals to be separated, Applied as a further natural treatment step to improve the protection of the environment. The essential novel features of the invention will be apparent from the appended claims.

Utilizing the method of the present invention achieves the technical advantages of certain processing methods. If neutral salts, such as ammonium, sodium, potassium sulphates, do not accumulate in the solution circulation, for example, the solubility of nickel sulphate is increased. This can be utilized to enhance the capacity of the reduction and electrolysis steps involved in the process. It is pointed out that, among other advantages, concentration, filtration and electrolysis are all easier. A high metal content improves the quality of the metal produced. Another particular advantage is that it is not necessary to separately remove the neutral salt from the main processing solution, for example by crystallization.

According to the present invention, in the present method comprising a smelting step, a leaching step of two useful metals, namely two metals called A and B, a recovery step by reduction and / or electrolysis It is further compensated by the characteristic extraction method that is compensated by the conversion. Other metals, C, are also utilized in processing where the metal is not necessarily a useful metal. From the recovery of the useful metal B, for example from the reduction treatment, a C-containing solution is led to a pre-extraction, the C-content of which is continuously increased to the extent that it compensates for the loss. The neutralizing agent used is substance D which is an ammonium, sodium or potassium salt. In the pre-extraction step, the extraction solution neutralized with the neutralizing agent D is mixed and contacted. Typically,
The extraction solution is kerosene-based and comprises, according to its extraction equilibrium, an extract suitable for extracting the metal A in the next extraction separation step, whereby the solution containing A, B and C is , Derived from the iron removal process. Used
The aqueous solution is advantageously a sulfuric acid solution.

In the pre-extraction, the extraction solution containing substance A corresponds to the C and D containing solution from the reduction. An ion exchange reaction was carried out and according to the reaction C was extracted into the extraction solution, at the same time all D exited the extraction solution into the aqueous phase and were exchanged leading to pre-extraction.
This leads to D-salt separation such as crystallization. The extraction solution containing the metal C is useful for the main extraction separation.
A guided, ion exchange is carried out between C and A together with an aqueous solution containing B and B. C is transferred to the aqueous phase, returned through the recovery of B, and returned to the pre-extraction for a new solvent extraction cycle. Thus, C
Acts as a form of exchanged ions, first displacing D from the extraction solution of the pre-extraction, but then water in the extraction separation itself.
Returned in solution . Therefore, C is a processing method, and D
Apart from the small amount with A and A, it is essentially not consumed, which can be compensated by the addition of small amounts before the pre-extraction. The metal A is again removed from the extraction solution by acid extraction and introduced into its own recovery circuit.

The method of the present invention is not bound to any particular metal or extraction solution. The essential point is that the extraction equilibrium promotes the extraction of metal A with respect to metals B and C. It is advantageous, but not necessary, that C be extracted more strongly than B. This helps to selectively extract A with respect to B. The metal is extracted, mainly according to cation exchange, with an extraction liquid which requires the addition of a neutralizing agent to accelerate the extraction reaction. Such extracts are di- (alkyl) -phosphonic acids, monoalkyl esters of alkylphosphonic acids and di- (alkyl) -phosphinic acids and organic carboxylic acids, commonly of the C-10 type. And many other acidic organic extract compounds.

[0017]

DETAILED DESCRIPTION OF THE INVENTION Described below is a typical process of the present invention for recovering cobalt in the context of producing pure nickel and in-process solution clarification. This processing method is further described in the flow chart of FIG. However, the present invention can also be applied to other metals,
It will be readily apparent from the above description and the examples below.

In this example, metal A is cobalt and metal B is nickel. C is preferably magnesium and D is ammonium. This nickel separation process is preferably arranged in connection with the nickel and copper smelting process. The objects of leaching are nickel sulfide concentrates and / or mats produced during the smelting process. The copper sulphide-containing material formed as a leaching residue is advantageously further processed in a copper smelting process for recovering copper and for recovering possible noble metals.

According to the method of the present invention, the magnesium-containing solution separated by hydrogen reduction is led to pre-extraction, and the extraction solution preliminarily neutralized with ammonium is supplied. This is advantageously due to di- (alkyl) -phosphinic acid, which is dissolved in kerosene. Further, the phosphinic acid is preferably di- (2,4,4-trimethylpentyl) -phosphinic acid, and cobalt and nickel can be separated due to its extraction property.

In the pre-extraction, almost all the magnesium is transferred to the extraction solution and the equilibrium amount of ammonium is returned to the aqueous solution . The aqueous solution then leads to the crystallization of ammonium sulphate. This treatment method ensures that the ammonium, which is advantageous for extraction, does not evolve in the nickel solution circulation. Also, so to speak, crystallization of neutral salts is avoided only in the main process flow.

The extraction solution, in magnesium form, is then directed to an extraction separation step, where it is contacted with an aqueous solution of cobalt-containing nickel. As can be seen from the extraction curve in FIG. 2, cobalt is more strongly extracted than Cyanex 272® magnesium. The extraction solution is a technical, di- (2,4,4-trimethylpentyl) phosphinic acid product . Thus, cobalt replaces magnesium from the extraction solution. The result is a cobalt-cleaned nickel solution and an extraction solution concentrated with respect to cobalt. For recovery of cobalt, the next step is acid treatment of the extraction solution and further treatment of the re-extraction solution described above.

With respect to magnesium, it does not interfere with the nickel recovery in the subsequent electrolysis and / or reduction, but remains in solution and can be reextracted with a preextraction during the next treatment cycle. The method of the present invention using magnesium as the exchange ion for cobalt thus prevents magnesium from accessing the process cycle. However, cobalt extraction is without the use of ammonium to facilitate extraction.
Seriously, the use of magnesium is necessary because it is incomplete.

In the above example, the metal A may be another metal that is removed rather than cobalt. A general requirement is that A be more strongly extracted than magnesium. In the process of the invention it is possible to remove metals such as zinc, manganese, cadmium, copper, iron, vanadium, molybdenum and uranium. Apart from the above group of cobalt or other metals, other metals of the same group or some other metals can be removed simultaneously.

In all of the cases described above, the useful metal B can, on the contrary, be cobalt instead of nickel,
Alternatively, B can be a solution mixture of nickel and cobalt. Therefore, the amount of each of the extraction solutions in ammonium and magnesium form used was smaller,
Thereby, the pH value of the extraction separation is precisely adjusted by the amount of extraction solution in magnesium form. Thus, the extractive separation is successful at a pH at which the metal to be extracted can undergo ion exchange with a cobalt-free extraction solution. In a manner similar to nickel, cobalt can be electrolyzed or reduced from magnesium-containing solutions.

The method according to the invention can be applied in a corresponding manner for clarifying a large number of solutions containing metals B and C. This is technically efficient and economical when B and C represent metals that can be separated by known methods.
The metal A to be removed in the extraction separation is more strongly extracted than the metals B and C, i.e. at a lower pH. B can be extracted more strongly than C. To obtain the desired extraction separation, the degree of extraction solution in which C is extracted is
The pH of the extracted separation is adjusted to be suitable for the metal separation described above.

Next, some examples of other metal solutions that can be treated by the method of the present invention will be given. When processing raw materials containing zinc, copper and cobalt, it is difficult to combine the use of ammonium leaching with ammonium as a neutralizing agent due to the limited solubility of the double salts containing ammonium and cobalt. . In the example in question, zinc represents metal A. On the other hand, the metal B can be copper, and each C can also be copper. The decisive factor is the comparative ratio of metal to other treatments. As noted above, A represents other metals that are more strongly extracted than B and C, such as iron and indium.

Other metal groups, such as zinc, manganese and copper, can be separated in a corresponding manner. In this case, A is zinc and / or iron. Manganese is B or C, and C can be copper.

The method of the present invention is not limited to the di- (alkyl) -phosphinic acid extract, but the sharpness of the separation allows
It is advantageous if cobalt is separated from nickel. In addition to this, with alkylphosphonic acids and monoalkyl esters of di- (alkyl) -phosphonic acids, the metals are extracted in the following order: UO22 +> Fe3 +> Zn2 +>
Mn2 +> Cu2 +> Cd2 +> Co2 +> Mg2 +> Ni2 +. Calcium does not behave consistently, but behaves according to the extract in question. In order to apply the method of the present invention, it has to be taken into consideration that the metals are divided into categories A, B, C according to their extraction behavior.

Carboxylic acids, generally C-10 acids, form the group of extracts used in the extraction. When the metals are arranged in groups according to the present invention, the following extraction order must be considered. Fe3 +> UO22 +> Sn2 +> Hg2 +> Cu2 +> Zn2 +> Pb
2+> Cd2 +> N2 +> Co2 +> Fe2 +> Mn2 +> Ca2 +> Mg2 +.

Other extracts working on the ion exchange basis can also be used for the metal separation according to the method of the invention. The most important of these are keratin-formers, such as oximes, which require neutralization. Neutralization is usually applied when the metal to be extracted has a high content in the leaching solution.

[0031]

As described above, ammonium or sodium is used to promote solution clarification, but solvent extraction is prevented by preventing ammonium, sodium or potassium from approaching the solution circulation. In order to avoid the formation of jarosite or ammonium and alkali-based double salts.

[Brief description of drawings]

FIG. 1 shows a flow sheet of a preferred embodiment of the present invention.

FIG. 2 is a graph showing the extraction of metals as a function of pH value with a fixed extract according to the invention.

Continuation of front page (56) Reference JP-A-3-10029 (JP, A) JP-A-51-103020 (JP, A) JP-A-57-73142 (JP, A) JP-A-62-27529 (JP , A) JP 53-141176 (JP, A) JP 49-55504 (JP, A) JP 55-18546 (JP, A) JP 55-65336 (JP, A) US Pat. (US, A) International publication 91/16465 (WO, A1) (58) Fields investigated (Int.Cl. ⁷ , DB name) C22B 1/00-61/00

Claims (5)

(57) [Claims] 1. An organic extraction solution of (1) di- (2,4,4-trimethylpentyl) phosphinic acid is added with ammonium,
Neutralizing with at least one of sodium base or potassium base; (2) leading the neutralized organic extraction solution to a pre-extraction step, where the organic extraction solution is contacted with an aqueous solution containing magnesium exchange ions The magnesium exchange ions replace ammonium or sodium or potassium in the organic extraction solution, and the aqueous solution contains ammonium or sodium or potassium; (3) Crystallize the aqueous solution containing ammonium or sodium or potassium And recover the ammonium or sodium or potassium salt; (4) contact the organic extraction solution, which is free of ammonium or sodium or potassium ions and contains magnesium, with an aqueous solution containing nickel and cobalt. And selectively extracting cobalt into the organic extraction solution, leaving nickel in the aqueous solution; (5) recovering cobalt from the organic extraction solution; and (6) recovering nickel from the aqueous solution. A method for preventing the formation of jarosite or ammonium or an alkali metal double salt in the leaching and solvent extraction of nickel and cobalt, characterized in that. 2. The extraction with the organic extraction solution comprises 60-
The method for preventing the formation of jarosite or ammonium or an alkali metal double salt in leaching and solvent extraction of nickel and cobalt according to claim 1, which is carried out at a temperature of 220 ° C. 3. Nickel is recovered by hydrogen reduction or electrolytic treatment. Prevention of formation of jarosite or ammonium or an alkali metal double salt in leaching and solvent extraction of nickel and cobalt according to claim 1 or 2. Method. 4. Prevention of formation of jarosite or ammonium or alkali metal double salts in the leaching and solvent extraction of nickel and cobalt according to claim 1 or 2, wherein nickel and exchanged ions are recovered by hydrogen reduction. Method. 5. The method for preventing the formation of jarosite or ammonium or an alkali metal double salt in the leaching of nickel and cobalt and the solvent extraction according to claim 1 or 2, wherein nickel is recovered by hydrogen reduction.