JPS5814860B2 - Thermal disproportionation method for copper salt solutions - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a process for the thermal disproportionation of a homogeneous solution containing a cuprous salt, water, a volatile organic nitrile, and an acid corresponding to the salt.

Details of the organic nitrile and cuprous salt will be described later.

The conventional method for extracting and refining copper is A. Written by Butts 'Co
pper the Metal its Alloys
and Compounds, New York, Reinhold Publishing Co., 1954.

The most common method is pyrometallurgy, in which crushed ore is flotated, then melted in an oxidizing atmosphere to form blister copper or anode copper, and finally passed through an acidic solution of cupric sulfate to form anode copper. This is a method of electrolytic refining to produce cathode copper.

Disadvantages of this process include sulfur dioxide pollution, high capital and operating costs, and loss of valuable material in the form of fumes and slag.

Another method is hydrometallurgy, ie leaching copper oxide or copper sulfide, optionally in the presence of ferric sulfate F, to give a solution of cupric sulfate.

Copper itself can be dissolved in hot sulfuric acid under oxidizing conditions, resulting in a cupric sulfate solution.

In these methods, the copper must then be removed by swiping a cupric sulfate solution by electrowinning or cementation.

More recent methods include treating the ore with oxidizing or reducing roasting agents, TORCO' separation, bacterial leaching, and leaching with ferric chloride or ammonia solutions.

However, all of these methods require the final step if one wishes to obtain copper of sufficient purity for many commercial processes.
In step T', it is necessary to perform electrolytic refining or electrowinning through an acidic aqueous solution of cupric sulfate.

In electrolytic refining, a typical tank house cycle is 11-1.
It is a slow method requiring 4 days.

A large number of tank house personnel are required, and there are various problems such as handling of anode materials, treatment of slime, short circuits and handling of cathode materials, treatment of slime, consideration of short circuits and the quality of cathode materials.

Electrowinning is also a slow process and has significant power consumption, but has lower costs associated with anode material handling when compared to electrorefining.

One main object of this invention is to provide a cuprous salt selected from cuprous sulfate, cuprous bisulfate, cuprous sulfite, cuprous bisulfite, and cuprous nitrate, and an acid corresponding to the salt. A homogeneous cupric salt solution containing nitrile or its azeotrope and precipitates the copper by distilling a homogeneous cupric salt solution containing nitrile or its azeotrope in a distillation tank. A method for the thermal disproportionation of a cupric salt solution is provided, characterized in that the copper is separated from the resulting acidic solution of the cupric salt.

Various other objects, advantages, and terminology will become apparent from the detailed description and discussion of the preferred embodiments below.

Some preferred aspects of the present invention will be described with reference to the accompanying drawings, but it goes without saying that the drawings are merely diagrammatic and do not limit the invention.

In the figure, FIG. 1 explains the design of the cupric extraction system.

FIG. 2 illustrates the design of continuous copper powder refining.

Copper can be recovered from an aqueous solution of the thermally disproportionated cupric salt of Cut by a reduction method other than electrowinning.

The process using solid reducing agents such as iron, nickel and zinc is known as the cementation process.

Methods using reducing agents such as sulfur dioxide, hydrogen and carbon monoxide are known as precipitation methods.

The cementation method has the disadvantage that the resulting "copper powder" is extremely fine, easily oxidized, and contaminated by solid reducing agents and other veneers that are simultaneously reduced.

The process is also inefficient because the reducing agent becomes coated with copper and no longer comes into contact with the cupric salt solution.

The precipitation method is usually carried out from an ammoniacal solution,
Requires high temperature and pressure.

Hydrogen is the preferred reducing agent; sulfur dioxide provides incomplete reduction even at high temperatures and pressures.

Currently, cement copper has to be refined by pyrometallurgy, and copper loss is a problem.

Thermal disproportionation of Cu+ from an acidic solution of the cupric salt in a mixture of volatile organic nitrite and water
- Precipitating the copper by removing the rill thermally, e.g. by distillation.

The solution is free of solids prior to harvesting, and if necessary, any dissolved impurities are removed prior to the harvesting step.

In this way pure copper can be obtained. The quality of the copper powder can be controlled from 1 to 1 depending on the additive Seed-1 and the precipitation conditions.

This powder is a more desirable product than the "copper powder" obtained by cementation methods.

This method is applicable to solutions of cuprous salts.

By controlling the pH, precipitation of Fe2+ salts and SOz- salts as well as Cu20 and CuOH can be prevented.

The concentration of acid affects the nature of the precipitated copper, and high acidity (above the H2S045 volume factor) tends to produce particles that are difficult to break apart.

The organic nitrile is removed in whole or in part from the cuprous salt solution, usually by efficient distillation, preferably under reduced pressure.

If it is carried out under reduced pressure, the boiling point can be lowered, and therefore 2) IJ
This minimizes the hydrolysis of the molecule.

Distillation is preferably carried out in the absence of significant amounts of oxygen, and the use of a reducing or non-oxidizing atmosphere can improve copper recovery.

2l- Extent and manner of agitation during IJl removal; 2l. The rate of copper removal and the presence of additives and seeds all affect the nature of the copper that is precipitated.

A solution containing glue and other additives such as sodium alkylaryl sulfonate and ammonium lignin sulfonate is added to the solution while stirring well.
It is preferable to remove the material gradually.

2) Riru usually occurs as an azeotrope with water.

When the ratio of 2-IJ to cuprous ions becomes less than 2-3 moles per mole of cuprous ions, the cuprous ions become disproportionated and become copper and cupric salts.

2Cu"-+Cu+Cu"+Continue removing 2l-IJ until the desired amount of copper powder is obtained.

This copper is removed by a conventional solid-liquid separation method (for example, centrifugation), washed, and dried.

This part of the method handles the copper powder and uses conventional techniques (see the Butts book) to separate the powder from the liquid and prevent its oxidation.

[Preferably, valuable 21.ril is recovered by distillation and washing from wet copper-1.

A preferred cleaning method uses a 21-lylu water distillate with added acid and returns it to the circuit.

The copper removed from the circuit is washed with acidified hot water and then with hot water in a non-oxidizing atmosphere.

If an oxidized aqueous solution of a cupric salt containing volatile
The thermal disproportionation method can be modified if the cuprous ion contains ions that are more easily reduced to metals than to copper, such as Ag.

The reaction that initially occurs as the nitrite is removed, for example with silver, is preferably carried out in more than one step.

This is because the first solid that precipitates contains a high proportion of substances that are easily reduced.

An alternative method for removing reducible specsies, especially in the case of solutions containing significant amounts of silver salts, is to cement the reducible specsies with excess copper prior to thermal disproportionation to form a colorless solution. Make it.

This thermal disproportionation method produces up to 50%
% of copper can typically be recovered, with the remaining 50% being cupric salts.

A highly desirable addition to the basic invention is to circulate the 21-lyl-free cupric salt solution as well as the distilled azeotrope containing nitrile and the wash solution, and then to -31776 or any other suitable method to regenerate the cupric salt from the cupric salt.

This is known as cuprous extraction, copper powder refining or cuprous leaching, depending on the reclamation method.

Copper extraction A preferred form thereof is shown in FIG.

In Figure 1, 1 is a distiller for disproportionating the cuprous salt solution, 2 is a reaction tank for reducing the cupric salt solution, 3 is a system for taking out copper powder, washing and drying it, and 4 is a volatilization system. Sex II I-I
5 is a storage tank for distilled 21-ril and its azeotrope, 6 is a system for dividing the distillate into approximately two equal parts, 7 is solid-liquid separation 8 is a system in which a reducing agent is added to the reaction tank, 9 is a system in which 21-lyl and its azeotrope is added to the reaction tank, and 10 is a system in which a small amount of 21-lyl is removed from the solution by distillation. A solution containing a cupric salt solution of 11 is a volatile organic di-IJ
12 and 12 respectively represent an acidic aqueous solution of a cuprous salt containing 1 and 1 and optionally additives and copper seeds, and 12 the solution from which the copper was removed, including the oxidized reducing agent.

An example is a cupric salt solution 1 in a solvent that displaces 21~lyl, prepared by thermal disproportionation of a cupric salt solution 11.
0 is recombined with the NitoIJ-water azeotropic fraction and the washing liquid (9
), the cupric salt is reduced by adding a suitable reducing agent such as iron or S02.

Cu2+-1-Red→Cu±-70x- (Red in the formula
(represents the reducing agent and OX represents its oxidized form) The reduced cuprous salt solution is filtered if necessary. The cycle consisting of removal of 21-ril, precipitation of copper, and reduction of cupric salt is repeated until the desired recovery of copper is achieved.

Ideally, the total mass balance could be expressed as Cu2++2Red-+Cu-1-20x-, but this would require an infinite number of cycles.

Therefore, selection is made and the small amount of copper remaining in solution must be recovered by other methods, such as cupric cementation with iron.

The "feed" to the thermal disproportionation that will later carry out the cuprous extraction process is provided by adding a sufficient amount of the appropriate two I-1 to a solution of cupric sulfate.
This is then used in the same process used later in the cuprous extraction process.
- Of course, it may be reduced with an appropriate reducing agent such as iron or S02.

Care is usually taken to avoid loss of valuable, volatile, toxic, and ignitable nitrile.

For example, the reaction may be carried out in a closed container or with a condenser attached.

This method is most suitable for sealed systems that exclude as much oxygen as possible.

Recovery and utilization of the oxidized form of the reducing agent, traces of undistilled nitrile, and traces of copper remaining in the spent solution form an economically desirable part of the process.

If SO is the reducing agent, the resulting acid can be used to leached the copper to produce a cupric sulfate solution, which can be reduced as described above to form a solution of cuprous sulfate or cuprous sulfite. Thus, a continuous "cuprous extraction method" can be achieved.

copper powder smelting This principle is illustrated in the preferred continuum method of FIG.

In Figure 2, 1 is a reaction tank for converting copper and cupric salts into cuprous salts, 2 is a reaction tank for removing insoluble impurities (slime), and 3 is a reaction tank for converting copper and cupric salts into cuprous salts.
4 is a system for adding copper-containing particulate matter to the reaction tank; 4 is a system for removing solids from a solution of cuprous salt; 5 is a distiller for disproportioning the cuprous salt solution; 6 is a nitrile or volatile component. Removal of the distillate containing its azeotrope, 7 the condensed nitrile or azeotrope thereof, 8 a system for dividing the liquid into two parts, 9 removal of the copper powder and its washing with the condensate, 10
11 is a system for further washing and drying copper powder, 11 is a solid-liquid separation system,
12 is a solution containing a cupric salt in a solution from which dil-lyl has been expelled; 13 is an acidic aqueous solution of a cuprous salt containing a volatile organic nitrile and optionally an additive; 14 is a solution 1
2 represents a system for purifying and adjusting its composition, and 15 represents a system for removing dissolved impurities.

The usual method for refining copper powder (see Butts, supra) involves a pyrometallurgical process followed by cupric electrolytic refining of the copper anode (for low-quality powders with a copper content of less than 98%).
Alternatively, the anode is melt-formed and then subjected to cupric electrolytic refining.

However, these methods have significant copper losses, are slow methods, and require considerable handling of the copper.

Also, in the case of "copper powder" and TORCO concentrates, complete melting and refining operations are required to produce pure copper.

The copper powder refining method of the present invention avoids the high capital investment of pyrometallurgy and also avoids the slow cupric electrolytic refining process.

This method produces purer copper from any finely divided copper-containing material more cheaply and quickly than any currently known method.

The invested capital is also relatively low compared to pyrometallurgy.

Although the process is based on thermal disproportionation, the preferred operation involves a solution of the appropriate cupric salt in a mixture with water containing a sufficient amount of the appropriate volatile organic nitrile acid. This is reduced using impure copper as a reducing agent.

The resulting cuprous solution is then transferred to distiller 5 and subjected to distillation to remove 2 l-IJL (6) and precipitate copper (9).
), and regenerate the cupric salt.

The cupric salt solution 12 and distillate 7 are combined and returned to reactor 1, where the reduction with copper(3) is repeated.

Ideally, therefore, the concentration of copper in the electrolyte remains unchanged;
The granular blister copper 3 becomes a purer granular copper 10.

Thermal disproportionation to distill off the nitrile and precipitate the copper from the cuprous solution has already been described, and the method for carrying out Reaction 1 will be described in detail below.

The process is preferably continuous, with copper leaching and copper precipitation being carried out several times in a reaction vessel and a settling vessel, respectively.

A conventional system for removing solids from the electrolyte is provided between the reaction vessel and the settling vessel.

A suitable material containing finely divided copper metal is prepared by a conventional solid-liquid leaching operation (see Butts, supra) in a container isolated from the atmosphere to form the appropriate cupric salt (preferably cupric sulfate). Stir the solution effectively.

The cupric salt solution is mediated by water and a sufficient amount of a suitable organic nitrile, preferably ace[-21.lyl, and is maintained acidic during the process with a suitable acid.

Although leaching is faster at higher temperatures, leaching temperatures of 40-65°C are preferred, although not absolute.

Copper and other oxidizable basic substances (e.g.
Iron, tin, copper oxide, arsenic, nickel and some bismuth) are melted into a cuprous solution and dissolved impurities.

Other impurities such as gold, limestone, alumina, carbonaceous materials, lead and significant amounts of antimony and silver do not dissolve but form "slime".

These are separated at appropriate intervals.

The cuprous solution is separated from the solids, for example by filtration, standing, or centrifugation, and the organic diluent is separated from the cuprous solution.

Separation of the volatile metals continues as described above until the desired amount of copper is separated and recovered.

The resulting cupric salt, after being combined with the nitrile-water distillate, is recycled to the leach tank and used to dissolve copper from the copper-containing material and produce a cupric solution.

Preferably, the method is carried out continuously.

21. The electrolyte that expelled Lil is the usual method (deleted Butts
(see his book) from time to time to maintain dissolved impurities, such as OX+, at acceptable levels consistent with the desired purity of the precipitated copper.

Of course, the copper powder refining may be carried out by a batch method using a Cu salt storage tank.

The cupric solution is removed and ultimately reduced with copper, using a distillate or other nitrile source.

Appropriate heat exchangers are desirable since, in principle, there is little energy consumption.

Since both the cuprous solution and the wet copper powder are oxidized to some extent by oxygen, oxygen should be excluded from the process as much as possible.

A reducing or non-oxidizing atmosphere (eg N2) is preferred.

Care should be taken to prevent loss of volatile, toxic and flammable liquid, and the process should be carried out in a closed system.

The solution is not particularly corrosive other than that in the leach tank.

The leaching tank must be resistant to the oxidizing power of Cu2 in the presence of nitrile.

Lead, glass and PVC are suitable materials, but stainless steel is not inert for long periods of time.

Cuprous leachingThis is very similar to copper powder refining, but in a preferred method, Cu2 mo is extracted from cuprous sulfide from a mixture of a cupric salt solution and a nitrile azeotrope obtained by thermal disproportionation. Alternatively, the cuprous salt is regenerated by reacting it with a substance containing cuprous ions and sulfide ions, or with cupric sulfide or a substance containing cupric ions and sulfide ions, respectively, in a leaching tank.

The resulting cuprous salt solution is filtered to remove sulfur, purified, and thermally disproportionated.

The net result is that copper sulfide is converted to copper and sulfur via cupric ions.

Since there is an equilibrium in these reactions, it is desirable to constantly remove the cuprous salt and sulfur and replace it with fresh cupric sulfate solution.

This cuprous leaching method has the advantage that unlike copper sulfide smelting, no sulfur dioxide is emitted, so there is no air pollution, and the cuprous salt solution obtained by immersion can be easily converted into copper. .

In principle, there is no consumption of chemicals. This method is simpler than the ferric sulfate leaching method, which is followed by electrowinning in aqueous solution.

Chalcopyrite is not effectively leached by this method, but if preheated with sulfur to above about 400'C,
Becomes leachable copper sulfide.

Preferably, a scheme similar to that shown in Figure 2 is applied to the continuous cuprous leaching process.

Suitable and Preferred Materials for Thermal Disproportionation The following expressions have been used in this specification and will be explained.

Suitable organic compounds such as acetonitrile, 2-hydroxycyanoethane and acrylonitrile are suitable organic compounds, which are suitable for their volatility, stability and homogeneity of composition. This is a preferable condition.

Although the expressions "organonitrile,""acrylonitrile," and "propionitrile" are used in this specification, many organic nitriles, including acrylonitrile and propionitrile, are miscible with water in all proportions. This is after recognizing that this is not the case.

Although the method of this invention requires a homogeneous solution, when homogeneity is required, the terms organic dichloromethane, propionitrile, and acrylonitrile may be used interchangeably with homogeneity. It is to be understood that this includes mixtures with sufficient solubilizing agents such as ethanol.

The terms "organonitriles" and "volatile organic nitriles" also encompass mixtures of organic ditriles and volatile organic nitriles, respectively.

Whether a nitrile other than acrylonitrile, 2-hydroxycyanoethane, or acrylonitrile with a solubilizing agent is suitable for the purposes of this invention can be determined by the following test.

Terms such as "organic nitrile" and "volatile organic nitrile" used in this specification refer to those of RON, acetonitrile, acrylonitrile, etc. that have passed the following tests. Refers to propioni 1 helium.

Nitrile general test 1~ 1. 5-x (molecular weight) g of the test nitrile was added to 513 g of sulfuric acid. Stir with 65.9 ml of water.

The solution in the stoppered container must remain homogeneous for at least 1 hour at 50°C.

la. If the solution is not homogeneous, add up to 30 ml of ethanol.

Keep the solution in a container with a stopper homogeneous at 50℃ for at least 1 hour.
It has to be.

If these procedures do not yield a homogeneous solution, the nitrile is unsuitable.

Add 204 g of CuSQ4,5H to the homogeneous solution prepared as in 2.1 or 1a and mix this with copper powder (
Stir at 50℃ for 1 hour with 2g (minus 100 mesh).

If the solution is homogeneous except for the undissolved copper powder,
And if it is colorless, becomes an extremely pale pale blue color, or if the nitrile itself has color, it shows coloration due to it,
Assume that the nitrile passes this test.

3. Nitrile solutions that pass Test 2 are flushed with nitrogen, capped and warmed to 50°C for 24 hours.

If the solution is homogeneous and is colorless or extremely pale blue, or exhibits the color of the nitrile itself, and has an IX10'll as measured by atomic absorption.
If it contains more than IIIn copper, the nitrite passes this test.

Special tests for nitriles The suitability of nitriles for thermal disproportionation (such as in extraction processes or copper powder smelting processes) is determined by their volatility.

4. Solutions that pass Test 3 are slowly distilled using an efficient distillation column.

The distillation is in some cases a distillation of a water-nitrile azeotrope, and in other cases, for example in the case of propionyl-1-lyl, a distillation of an ethanol-nitrile azeotrope.

For example, if a nitrile with a coefficient of 75 or above can be distilled below 90°C, as measured by VPC of the distillate, then
The nitrile is qualified as suitable for thermal disproportionation if some copper precipitates upon complete removal of the nitrile.

Two l-IJs that pass tests 1-3 but fail the distillation test below 90°C in test 4 are deemed unsuitable for thermal disproportionation.

Test 4 21.ril which distills below 90°C is defined as volatile, but as such is suitable for thermal disproportionation methods.

We tested dicyanomethane, acetone cyanohydrin, hydroxycyanomethane, and phenylcyanomethane, but
These nitriles were found to be unsuitable.

Generally speaking, a suitable organic nitrile is one that maintains a stable homogeneous solution of cuprous sulfate when mixed with water and sulfuric acid in the appropriate ratios of each component for a particular process ( It is an organic nitrile (containing an inert solubilizing agent).

Commercially, the 21-helyl must not degrade to an economically unacceptable extent under conditions of thermal disproportionation.

As already mentioned, the term suitable or appropriate organic nitrile encompasses mixtures of nitriles, for example acetonitrile containing some acrylonitrile is a by-product of the production of acrylonitrile and is an economically advantageous mixture. It is.

However, since AkuIJ-nitrile is only partially miscible with water, it is necessary to reduce its proportion or to incorporate appropriate solubilizers (for example methanol) into the composition.

Preferred organic nitriles include volatile acetonitrile and, to a lesser extent, volatile propionitrile (combined with methanol or ethanol as a solubilizer) and acrylonitrile (combined with a solubilizer).

Volatile and stable acetonyl-1-lyle is highly preferred for processes involving thermal disproportionation, such as cuprous extraction processes and copper powder smelting processes.

This is because there is a distillation step and the boiling point of the water-acetonitrile azeotrope is 80°C or lower.

Inert solubilizers These are substances for producing a homogeneous solution containing cuprous salt, acid, water and a sufficient amount of the appropriate organic nitrile in proportions suitable for the process of this invention.

The term solubilizer as used herein, of course, refers to an inert solubilizer.

These can be used when the appropriate organic nitrite is only partially miscible with water (e.g. a certain proportion of propionite IJ).
It is used for acrylonitrile and acrylonyl (1).

The solubilizing agent can then be tested as in Test 1a-4 above, replacing the ethanol in Test 1a above.

Preferred solubilizers are ethanol and methanol.

As already mentioned, "appropriate (or appropriate) Nito IJ"
The term "volatile organic nitrinol" or "volatile organic nitrino-1" is to be understood to mean the combination of 21-lyl and a solubilizing agent, if the nature of the material requires it.

Given a sufficient volume of a suitable cuprous nitrile salt solution, the nitriles determined to be suitable by the method outlined above are present in a sufficient proportion to stabilize cuprous ions in water. However, because nitriles are expensive, it is desirable not to exceed the amount necessary for satisfactory performance of a particular process.

In the absence of an oxidizing agent such as oxygen, stable solutions of certain cuprous salts can be made in water containing the appropriate acid and 2-3 moles of organic nitrile per mole of cuprous ion. I understand.

Since oxidation is rapid in solutions with low nitrile content (see Table 2), under normal operating conditions, where complete exclusion of air is difficult, if a stable solution is required, the appropriate 2 l- Preferably, 5 to 6 moles of IJ are used.

In the case of thermal disproportionation methods, there is little benefit in using more than 6 moles of volatile nitrite per mole of Cu+.

This is because the nitrile must be distilled off.

For some methods used to produce cupric salt solutions, a higher proportion of 21 helices may be required to push the appropriate equilibrium far to the right.

The composition of such cuprous salt solutions is preferably adjusted before thermal disproportionation, for example by addition of water, acid or by rapid distillation of the nitrile.

In this specification, when reference is made to the use of IJ, it should be understood that the amount used satisfies the above requirements, unless otherwise specified.

Another limitation on the amount of nitrate is that it must form a homogeneous composition.

Additives Mention is here made of a number of additives known to improve the quality of copper cathodes (see Butts supra) and to alter the properties of copper powder precipitated from cupric solution, for example by hydrogen.

Additives other than thiourea, long chain alkylaryl or alkyl sulfonate, ammonium lignosulfonate, sodium thiosulfate and glue have not yet been fully tested as part of this invention;
Note that additives are also desirable in disproportionation.

In this specification, ammonium ligninsulfonate is included in alwylsulfonate.

Such additives also appear to alter the physical properties of the copper grains (discrete grains are highly desirable) that are precipitated by thermal disproportionation.

In particular we use copper seeds, 0.1% sodium alkyl arylsulfonate (AVITONE), sodium thiosulfate and ammonium likuninsulfonate (ORZA
N) has been found to produce improved crystalline precipitates from thermal disproportionation of cuprous salt solutions.

Preferably, the additives are used in a proportion of 10 to 10,000 ppm.

Reduction of cupric sulfate in the presence of suitable reducing agents water, sulfuric acid and organic nitrile produces cuprous sulfate or IIc uH S 0
4 solutions are produced.

In principle, agents known to reduce cupric ions to copper in water can also reduce cupric sulfate to cuprous sulfate, and often even to copper, in acidic water-nitrile mixtures. Probably.

However, solubility, side reactions, etc. may prevent effective formation of a suitable cuprous salt solution.

The following are recognized as suitable reducing agents; in this specification, unless otherwise specified, the term reducing agent shall refer to them.

This is because they are present in sufficient amounts to stabilize cuprous ions (i.e., 2.0% nitrile per mole of cuprous ions).
This is because cupric sulfate is reduced to a cuprous solution in an acidic aqueous solution containing 5 moles or more of acetonitrile.

i.e. iron, nickel, cobalt, copper, cadmium,
Zinc, tin, sodium bisulfite, sulfur dioxide and sulfite.

As already mentioned, cuprous sulfide, cupric sulfide, nickel sulfide and silver also contain relatively high proportions of organic di-I-IJ
is a suitable reducing agent.

The ratio of the reducing agent used is such that the reduction reaction of Cu2+→Cu+ is satisfied (for example, 1/2 mole of iron reduces 1 mole of cupric sulfate to cuprous sulfate).

Copper salt, cupric salt, cuprous sulfate, Cu HS 0 4,
Certain suitable cuprous salts and suitable acids.
Deal with bisulfites and nitrates.

The acid is sulfuric acid, sulfurous acid or nitric acid.

In this specification, it is described as a solution containing cuprous sulfate, CuHSO, cuprous bisulfite, etc., but the cuprous salts are not isolated as solids from the solution, nor are the salts identified. .

Therefore, these terms in this specification may lack some precision.

However, it is certain that the solution contains cupric ions and that the disproportionation gives copper.The solutions prepared as described in this specification are designated as above. Based on the method of preparation of these solutions, I believe that they are solutions of salts such as those mentioned above.

The term "cuprous sulfate" refers to bisulfate and CuHSO4
and. Represents sulfate.

In the presence of SO2, other salts such as CuHS03 would also have been present, for example during copper disulphate reduction.

CuHSO4 appears to be a more soluble species than CU2S04.

Similarly, reactions as represented by equations may not proceed exactly as those equations specify.

Cuprous sulfate solutions containing sulfuric acid are suitable salts and acids for all thermal disproportionations.

Cuprous nitrate and small amounts of nitric acid are suitable for certain aspects of thermal disproportionation at low acidity.

When nitric acid exceeds 0.3N, it dissolves a portion of the produced copper powder and oxidizes cuprous ions.

Nitrates tend to be more soluble than sulfates (Table 3)
Therefore, solutions with acid concentrations lower than 0.3N are advantageous for thermal disproportionation.

Similarly, in the preparation of cuprous nitrate solutions, it is undesirable to use cupric nitrate containing more than 0.3 N of nitric acid, and in fact becomes impracticable at high nitric acid contents.

Cuprous sulfite is not significantly soluble in a 2 l-IJ-water mixture, and cuprous bisulfite, CuHS03, mixed with CuHS04 in a sulfurous solution has a high heat resistance in the method described above. Suitable for general disproportionation process.

"Copper sulfite" and "cupric bisulfite" are excluded from the copper salts described in this specification.

In order to obtain a solution of cuprous bisulfite, the pH must be carefully controlled.

Anions that form water-insoluble cuprous salts and complex with cuprous ions, such as Cl-, CN-, S, B
Since r- do not form cuprous salt solutions of sufficient concentration for satisfactory disproportionation, these salts are excluded from the term "cuprous salt solutions" herein.

As a rule, the most soluble cuprous salts and "inert"
Although anionic acids are suitable, cuprous sulfate solutions in sulfuric acid are highly preferred for disproportionation.

The acid concentration must not be so high as to cause uneconomical loss of nitrile by hydrolysis, but must be high enough to control impurities.

Suitable Copper-Containing Materials The following are examples of materials that have been found suitable for copper powder refining.

All were used as at least =16 mesh material.

Cuprous powder or cement copper (see Butts); atomized r'#A (blister)
J copper, scrap copper, and anode copper (each divided, for example, by atomizing with vapor of molten copper, see Butts); tinned copper ingots (tinned
coppernuggets), shavings (shav)
Copper alloys (for example, most brasses) containing copper with a coefficient of 65 or higher, such as ings); copper metal in slag mass; concentrates from the TORCX) process; copper-lead from lead smelting; Dross and materials containing copper, silver and gold, such as anode slime, copper precipitated by aqueous surface reduction from solutions of copper salts, are considered suitable but were not tested.

Other substances such as copper oxides and copper sulfides are discussed, as well as minerals, ores, glues, etc. that contain these substances.

A suitable and preferred composition thermal disproportionation relies on providing a homogeneous solution of the appropriate cuprous salt in an acidic aqueous solution containing organic di-lyl.

A suitable general composition for use in disproportionation is cuprous sulfate with an analysis of about 2-5% Cu+ in sulfuric acid-containing water and about 15% Cu+.
~20 volumes of volatile acetonitrile plus additives and seeds.

The particular composition is limited by factors such as the solubility of the cuprous and cupric salts at the appropriate stage of the process.

The above condensation product is based on the relationship between the ratio of nitrile required for solvation of cuprous ions (at least 2 to 3 moles per 1 mole of Cu), the miscibility of nitrile, and the appropriateness of the anion accompanying the cuprous cation. copper properties, the need to maintain the solution at an appropriate pH, and the desired purity and physical properties of the copper in the composition.

Taking these factors into consideration, the following compositions are preferred.

Thermal Disproportionation Cuprous Extraction and Copper Powder Refining With the removal of the volatile nitriles, the solution is prepared with cupric sulfate in the desired proportions matching the solubility of the starting materials; water; sufficient sulfuric acid (preferably 1 to 2% by volume) to maintain acidic conditions throughout the period, and a suitable volatility of 2.5 to 10 moles (preferably 4 to 6 moles) for each mole of cupric ion present. 10 to 10 organic dichloromethane,
Preferably it contains 0 00 ppm of additives and copper seeds.

For copper powder smelting, cupric sulfate in 1 to 4 volumes of sulfuric acid, water, and 7 to 20 moles of volatile ditole per mole of cupric ion are used, with additives. ,
It may be more advantageous to start with 25 g of freshly prepared cupric sulfide of 3-60 mesh in a reaction vessel with 110
g of C u S 04 ・5 H2 0, 1100 ml
of acetonitrile, 1000 ml of water and 1]. Om
The mixture was stirred for 1 hour at reflux with a composition consisting of 1 ml of sulfuric acid.

The blue hue rapidly decreased in intensity and agglomerated sulfur was seen to form.

When the solution was separated, 5 g of a gray material remained.

The material contained 0.15 g of copper and was soluble in carbon disulfide, which was evaporated off to yield yellow sulfur.

The P solution contained 44 g of copper.

This amount conforms to the quantitative relationship shown in Reaction Formula 5.

A thermal disproportionation reaction yielded 9 g of copper powder contaminated with a small amount of cuprous sulfide.

The following examples are intended to illustrate the invention.

Example 1 5g of CuS04H 5H20 is placed in a closed container. 5
It was reduced by stirring for 20 minutes in water saturated with ml of acetonitrile and 35 ml of isomeric sodium bisulfite.

A light green solution of the cuprous salt formed.

This was acidified with 2 ml of sulfuric acid to cause a thermal disproportionation reaction.

The residue was washed with IN sulfuric acid to obtain 0.5 g of metallic copper (80% yield).

Example 2 10 m9 of CuSO4.5H20 were reduced by shaking under atmospheric pressure for 2 hours with a mixture of 15 ml of ace1.nitrile and 50 ml of water saturated with SO.

As the C u S 0 4 reacted and dissolved, additional S 0 2 was bubbled into the solution.

The solution was thermally disproportionated and the solid was washed with sulfuric acid to a concentration of 0.5
Yield: 40% to obtain 5 g of copper).

10 Repeat experiment (2) in the presence of v/v H2804.

The yield decreased to 0.05-0.9g (4-8oI)).

Experiments were conducted under 6 atm and 100°C, saturated with SO2 (
2) was repeated.

(The solution is saturated at room temperature, sealed, and heated to 100°C.

) The copper yield improved to 1.0 g (80%).

Experiment (2) in the presence of 10% v/v H2SO4
repeated.

The copper yield decreased by well over 20%. Example 3 A solution containing cupric sulfate in 100 ml of water was treated with ammonia to obtain a dark blue solution.

50 ml of acetonitrile was added to saturate with solution S02.

As more SO2 was added, the solution turned from blue to green to yellow and the pH decreased.

Thermal disproportionation of the yellow solution yielded some copper powder.

Example 4 Example for the above reaction and thermal disproportionation of the resulting solution (a) 25 rd acetonyl l-1), 2 m
5 parts by weight of C in a mixture of 1 sulfuric acid and 73 ml water.
A cupric sulfate solution containing u2+ at 50°C was vibrated with 0.5 g of powdered metal (approximately -60 mesh) in a sealed reaction vessel under a nitrogen atmosphere to dissolve the metal and form a clear solution. I continued to vibrate until I got it.

The results are shown in Table 1. Table 1 Reduction of cupric sulfate to cuprous sulfate and complete dissolution of metal by the above reaction Metal time min b (Cu+)0%Fea
80 89 N i 6 0 10 0
Cd 60 60Zna
40 66 a) Hydrogen was also generated.

b) This is the time required for complete dissolution.

c) For Cu+ the values found after complete dissolution of the metal are shown.

It is expressed as a percentage based on the theoretical amount of Cu+ calculated from the quantitative relationship shown in Reaction Formula 8.

(b) An iron nail weighing 0.92.9 mm was placed in a closed container with a cupric sulfate solution containing 2 parts by weight of Cu2+ in a mixture of 30 ml acetonitrile, 5 ml sulfuric acid and 70 rd water. Shake at room temperature.

The nail completely dissolved within 24 hours.

The solution was colorless.

No copper powder was detected in the reaction vessel.

When the solution is filtered and thermally disproportionated, 0.005%
0.92.9 of copper containing iron was obtained.

A secondary experiment was carried out using 30 ml of water to replace the entire amount of acetonyl 1.Lyl and a solution containing only 1 part by weight of Cu2+. A copper-coated nail was obtained in the solution.

Copper-coated iron nails also contained a significant amount of iron in their core.

And the solution was still blue after 5 days.

Thus, water-based cementation was extremely ineffective.

(c) Kotspur Refineries Pty. Copper Refineries
Pty. Ltd. ) in water provided by
200 ml of tankhouse electrolyte containing 2+ and 10% v/v sulfuric acid was treated with 50 ml of acetonitrile and 4 g of iron powder.

A small amount of hydrogen was generated while the iron was coated with copper.

After 2 hours, the blue color of cupric ions disappeared and a light green solution of cupric sulfate and ferrous sulfate was formed.

When this was filtered and thermally disproportionated, 41 g of copper powder containing 30 grams of iron was obtained.

The solubility of metal sulfates in the lil-water mixture is of course based on the solubility of these metal sulfates, but the sulfates of nickel, iron, cadmium, and cobal 1 were all acidified. Very well soluble in acetonyl-IJ-water mixture.

Thermal Disproportionation of Cuprous Salt Solutions A cuprous sulfate solution was made in a reaction vessel in 500 ml of a sulfuric acid acidic mixture of water and acetonitrile, using a composition within a well-preferred range.

Each solution was centrifuged to remove all suspended solids and added with approximately 0.1 weight part of gelatin or Avitone (a sodium alkylaryl sulfonate) or ORZA.
N (a type of ammonium liquinine sulfonate) was added.

The solution was transferred to a settling vessel and slowly distilled under a gentle stream of nitrogen through an efficient column of a distillation apparatus equipped with a magnetic stirrer.

The solution was strongly colored an ultramarine blue color and was approximately o.o. when the first traces of copper powder were deposited in the solution during stirring. I weight of good quality copper powder was added as seeds (nuclei).

Distillation was continued gradually until all the nitrile-water azeotrope was removed.

The solid copper was separated from the blue solution by decantation and the copper powder was washed thoroughly, first with the acidified azeotrope described above and then with hot water.

The first wash and the above distillate were saved.

The copper powder was quickly dried.

Very little oxidation was observed. Yields were >90% in all cases based on effective cuprous ion disproportionation and subsequent distillation above the azeotropic point until all nitrile had been removed.

Although the above was a general operation, it has been modified in various ways.

The next data is the related data.

The >90% yields noted above resulted from virtually complete ace-1121-lyl removal (i.e., distillation above the azeotropic point).

Effect of pressure At 100°C in 10% H2S04, rapid acetate
It is advantageous to minimize hydrolysis of the nitrile and therefore distillation at 50-60°C under reduced pressure may be preferred.

Table 2 shows some relevant data.

Table 2 Distillation of cupric sulfate solution in acetonitrile-hydro-acidic mixture (Cu" 5 parts by weight, 20% M e C N, 5 parts H2S
04 and water) 5 Pressure ±10rnyn Azeotropic mixture boiling point 3715
74°C 43061°C 365 56°C 260 51°C a) The azeotrope composition is 85-90% v/v ace1
~ Nitrile water.

b) This solution precipitates copper with a yield of >90%.

Effect of precipitation Copper powder has enough acetonyl 1-lyle removed to form acetonyl-1
- No precipitation occurred until the ratio of IJ+ to Cu+ was reduced to 2.5:1.

Therefore, an excess of 1 heliyl acetonate over this ratio can be removed quite rapidly without significantly affecting the thermal disproportionation.

Once the ratio of acetonitrile to cuprous ions is approx.
．． Copper recovery is eliminated when the ratio decreases to 5:1.
The relationship was almost a -order function with respect to the volume of IJ.

In summary, a saturated solution of Cu2SO in 25 volumes of acetate, 0.5 volumes of sulfuric acid, and water has approximately so% V/V of the acetonitrile present distilled out as its azeotrope. At one time it gave away 70% of the copper present.

As more acetonitrile is removed at higher temperatures, more copper is precipitated, but in many thermal disproportionation applications the undisproportioned cuprous ions are recycled and Since high temperatures must be avoided for hydrolysis, it was preferred to remove to the point that no more azeotrope was removed.

Effect of Acids Sulfuric acid was preferred for thermal disproportionation because acids such as nitric acid oxidize copper and cuprous ions when present in amounts greater than 0.2 moles.

The amount of acid chosen will depend on the impurities in the cuprous solution.

Therefore, copper containing less arsenic, iron, antimony, and bismuth has less H2S041 than a solution with a volumetric coefficient of
It was obtained when thermal disproportionation was carried out with a solution of 2SO42 volume or higher.

Copper arsenate is formed when the acidity of a solution containing copper and arsenic decreases.3 Generally, solutions containing 1 to 2 volumes of sulfuric acid are thermally disproportionated, but this is influenced by impurities. be done.

Effect of distillation An efficient column was a requirement.

With only one partial condenser, the distillate quickly rose to 90°C.

The distillate is therefore Cu2S02. CH3CN,H2
When the S04,H20 composition was thermally disproportionated, it contained a low proportion of ace1121-lyl.

Copper grade The produced copper sometimes formed into plate-like shapes at the gas-liquid interface, but was usually a coarse "sand-like" powder.

It was easy to clean and did not seem to oxidize very easily.

An improved fine discontinuous powder was obtained by the presence of copper seeds (nuclei) immediately before disproportionation.

Other additives (approximately 0.1% by weight) had a distinct effect on powder quality.

Thus 1,000 urea, manganese sulfate and ferrous sulfate give a flocculent precipitate, sodium thiosulfate gives a coarse powder, rare gelatin, ORZAN (ammonium lignin sulfonate) and AVITONE (alkylaryl sulfonate) Soda), a commercially available copper smelting additive, provided a high purity discontinuous powder of excellent grade.

Copper Purity AR copper sulfate was used to prepare a cuprous solution in an acetate 1.2 l-IJ-water mixture.

Various other salts were included in the solution.

The solution was thermally disproportionated in a conventional manner to obtain a much purer copper powder than the copper-containing raw material.

Cuprous sulfate solution (Cu 1,3 parts by weight, H2SO4 1,5 parts by volume, acetonyl l-IJ 30 parts by volume, and water 68 parts)
．． 5% by volume) was added to contaminate the sample.

The solution was filtered and thermally disproportionated using conventional methods.

The precipitated copper was analyzed and the results shown in Table 3 were obtained.

Silver in the cuprous solution was removed by precipitation with copper prior to disproportionation.

The tin, apparently dissolved as a stannous salt, was oxidized to insoluble stannic during the disproportionation, as evidenced by the precipitation of a tin-containing white solid along with the copper.

This contaminated copper was subjected to secondary dissolution and thermal disproportionation according to Reaction 1 to give significantly tin-free copper.

A tin-containing white solid formed when the solution containing the stannous salt was refluxed with cupric sulfate.

This solid was filtered and then disproportionated to yield substantially tin-free copper.

Table 3 Additive ppmdC to Cu+, . ppm”.

FeS04600,000 120NiSO4
600,000 140SbO
” 6.000 36023 AgNO3a 60,000a 8PbN
03 60,000b 12a) The solution was treated with copper powder to precipitate silver before thermal disproportionation.

b) Lead sulfate was distributed door to door.

C) By analysis of copper after thermal disproportionation.

d) Amount (parts) of metal additive per million parts of copper detected in the solution by addition of salt.

e) detected in copper produced by thermal disproportionation,
Amount of metal additive (parts) per million parts of copper.

Effect of cuprous salts Thermal disproportionation of C 11 2 804 or C u H SO 4 was common and proceeded as described above.

It was prepared under the conditions of reaction 1 by treating 4 g of copper powder with 10.9 cupric nitrate in 150 ml of 30% V/V acetonyl-IJ-water.

A cuprous nitrate solution containing 0.75% nitric acid was thermally disproportionated to yield 2.9.9 copper.

Dissolution of some of the copper powder in reaction 1 with nitric acid resulted in a yield of 110%.

500 ml of a solution of cuprous bisulfite (cupric ion analysis value 2 to 4) in a 25 acetonitrile-water mixture containing sulfurous acid prepared by reaction 12 was heated to a thermal disequilibrium until 200 ml was distilled off. It became.

A small amount of Cu2SO3 precipitated with copper, but 1NH2
This was disproportionated to steel and cupric sulfate by washing with SO4.

The copper yield was >85% based on cupric disproportionation.

Effect of nitrile 20% acetonitrile containing acrylonitrile by volume 2
A composition of cupric sulfate containing 5 parts, water, 2% sulfuric acid, and 1,4 parts Cu (by weight) was thermally disproportionated.

The copper yield was >90φ based on thermal disproportionation of Cu+.

In other experiments, 10 g of finely ground copper residue (-1oo mesh)
of CuSO4.5H20 in 500 ml of a solution containing 30% acrylonitrile, 35% ethanol, 35% water and 5% H2SO4 (each in volume %).
It was stirred with 35 g.

The solution, which lost its color after 1 hour, was filtered and thermally disproportionated at 69-71°C until the acrylonitrile was removed.

9g of copper contains 30ppII1 of lead, 14pvm of silver, and selenium
30 ppm, and nickel (IIll)In was precipitated.

The blister copper contained ten times this level of impurities before this treatment.

Effect of oxygen Acidity 25 Acetonitrile - Cu 2 S in water
The o410 gravimetric solution (initial) was blown with air during thermal disproportionation.

The copper yield decreased to 30% due to the disproportionation of Cu.

Effect of cupric sulfate Highly concentrated solutions of acetic acid (e.g. 50% by volume) and cuprous sulfate (e.g. Cu + 14% by weight) are often combined with copper after thermal disproportionation and cooling. Precipitate copper.

In such cases, the solids were washed with hot water to remove cupric sulfate.

A solution of about 10% by weight Cu2SO4, 20-25% acetonitrile, water and 1-2% by volume H2SO4 500
The copper powder refining and cuprous extraction experiments from ml are summarized below.

The general operation of thermal disproportionation of a copper powder refining stable solution is carried out in a precipitation vessel, and the solution after removal of the acetonitrile-water azeotrope is then transferred to a reaction vessel by a pump and heated for 50 minutes under nitrogen. ~6
Mix with the azeotrope while maintaining a sealed system at 0°C.

The acidity was checked and a small amount of H280 was added to bring the concentration back to 0.5N.

This solution was mixed with finely ground blister copper (-16~
+100 mesh) with an excess amount (31).

The resulting cuprous sulfate solution was filtered from the reaction vessel.

Approximately 1 g of glue was added and the thermal disproportionation was repeated in the precipitation vessel containing the previous copper powder.

This cycle was repeated three times without any significant change in the yield or purity of the resulting copper powder.

The equipment used uses a screw pump to move the solution from the reaction vessel to the precipitation vessel.

They were arranged using the method shown in Figure 2. A general procedure for cuprous extraction and thermal disproportionation was carried out with solutions of known concentrations of Cu.

The solution was transferred from the precipitation vessel to the reaction vessel after removal of the acetonitrile-water azeotrope and recombined with 1/2 of the azeotrope while maintaining the sealed system under nitrogen.

This solution was treated in a reaction vessel under the conditions of the reaction (Example 4) with about 7 g of iron powder (ie 0.25 moles per mole of Cu+ in the initial solution).

The resulting solution of ferrous sulfate and ferrous sulfate was filtered, acid was added to maintain an acid >IN, and thermally disproportionated in a precipitation vessel containing the initial precipitate.

This cycle is repeated using the same reaction vessel and the same thermal disproportionation precipitation vessel, this time using 3.59 iron powder (i.e. 0.1.3 moles per mole of C 11 + in the initial solution). Ta.

Approximately 80% of the available copper was recovered in this manner.

[Brief explanation of drawings]

The attached figures are all diagrams, but Figure 1 is for explaining a system suitable for the copper extraction method, and Figure 2 is a flow diagram for explaining a system suitable for the continuous copper powder refining method. It is a sheet.

Claims (1)

[Claims] 1. A cuprous salt selected from cuprous sulfate, cuprous bisulfate, cuprous bisulfite, and cuprous nitrate, an acid corresponding to the salt, and a volatile organic dihydride. A homogeneous cupric salt solution containing 1.1 chloride and more than 50 volumes of water is distilled in a distillation tank to distill off the nitrile or its azeotrope and to precipitate the copper, and the resulting A process for the thermal disproportionation of cuprous salt solutions, characterized in that the copper is separated from an acidic solution of cupric salts. 2. In the thermal disproportionation method according to claim 1, the cupric salt solution produced by the thermal disproportionation is diluted with 2 l-
combining the IJ-containing distillate, treating it with a reducing agent to form a cuprous salt solution, subjecting the cuprous salt solution to a thermal disproportionation reaction, and repeating these steps. Features: Cuprous extraction method for extracting copper from cuprous salt solution. 3. In the method for thermal disproportionation of cuprous salts (excluding cuprous bisulfite) according to claim 1, the cupric salt solution produced by thermal disproportionation is converted into a distillate. and treated with a copper-containing substance in a reduction tank to reduce the cupric salt solution and oxidize the copper to make both into a cuprous salt solution,
A process for refining copper powder, characterized in that the first blunt salt solution is separated from the solids and returned to the distillation tank for further thermal disproportionation reactions, and these are repeated.