DE2338324A1 - PROCESS FOR RECOVERY OF COPPER - Google Patents

Description

Patent attorneys

Dr. Dieter F. Morf

Dr. Hans-A. Brauns June 27, 1973

S w.u.iJne.1 ~,.-.— Äiauerstr. 28 Docket 41

THE SHERWIN-WILLIAMS COMPANY 101 Prospect Avenue N.W., Cleveland, Ohio 44ll5, V.St.A.

Process for recovering copper

In Chem. Ber., 90, Volume 6, (1957) pages 841 to 862, it is suggested to anthranilic acid esters by diazotizing the esters and adding an acetic acid solution containing CuCl ₂ , dissolved S (X) and a large excess of HCl in transfer the corresponding sulfonyl chloride. It has been found that in practicing this technology it is advantageous to separate the sulfonyl chloride by extracting it with an organic solvent such as trichlorobenzene. After such a separation, the copper chloride remains dissolved in the aqueous phase, which is a by-product stream. Because of its toxic nature, copper must be removed from this by-product stream for environmental reasons. However, it has been found that precipitating a filterable copper precipitate from this stream is difficult. For example, if only a stoichiometric amount of sodium hydroxide is this aqueous

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By-product stream is added, a slimy one forms Precipitation, which at best can only be filtered with extreme difficulty.

The present invention is based on the discovery of a way of producing an easily filterable copper precipitate in the above-identified aqueous by-product stream. The aqueous phase, which contains copper and other metallizations, is separated from the organic solvent phase. The copper cations in the aqueous phase are precipitated as copper carbonate. The term "copper carbonate" as used here relates to copper (I), copper (II) and mixed copper (I) -copper (II) precipitates which are formed by reaction between copper cations and parbonate anions; It goes without saying that the precipitates can be basic carbonates or mixed salt carbonates which ^{contain Cl ", SCL s} or other anions (cf., for example, Kirk and Othmer, Encyclopedia of Chemical Technology, 2nd Edition, Volume 6, (1965)) , Inter-science Publisher, pages 260 and 2-0). The aqueous phase containing the filled copper carbonate is heated in order to convert the copper carbonate into an easily filterable state. The copper is obtained by separating the precipitate from the aqueous phase.

It is therefore an object of the present invention to provide a method for recovering copper in an aqueous by-product stream to be translated.

Another object of the present invention is to provide a process for recovering copper in an aqueous by-product stream resulting from the conversion certain diazonium chlorides into the corresponding sulfonyl chlorides originates.

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Docket 41

Summary;

Disclosed is a method for recovering copper. The process is applicable to the recovery of copper ions which are dissolved in an aqueous by-product stream which additionally contains other metal ions. In a special embodiment, the process for the recovery of copper comprises the following steps: the Jüipferkationen are precipitated in the aqueous phase as a copper carbonate, which is probably not a simple carbonate salt; the aqueous phase and the precipitated copper carbonate are heated to a temperature of about 90 ° C. for a sufficient time to convert the precipitate into an easily filterable state; and the precipitate is separated from the aqueous phase.

The method according to the invention is applicable to both discontinuous and continuous modes of operation. Example 1 illustrates one embodiment of the batch process.

example 1

The conversion of methyl anthranilate to methyl anthranilate diazonium chloride and the subsequent conversion of the diazonium chloride reaction product to o-carbomethoxyphenylbenzenesulfonyl chloride was briefly outlined after the above with reference to the treatise in the Chemical Reports Chemistry performed. Trichlorobenzene was added to the reaction mixture that contained the o-carbomethoxyphenylbenzenesulfonyl chloride, was added and Clg gas was bubbled through. By chlorination of the reaction mixture, the copper (I) ions were converted into copper (II) ions * The aqueous by-product phase, which contained dissolved copper (II) ions, was then separated from the organic trichlorobenzene phase and afterwards Working method neutralized.

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A solution of Na ^ CO was prepared by adding a 1200 g portion of ^ 2 ⁰ O * ^to ^ ^{000 ml of} distilled water. The solution was heated and stirred until all of the M ^ CCL was dissolved. The solids were then removed by filtration and the solution was kept at a temperature of 35 ° to 40 ° C.

The pH of a 25 ml portion of the aqueous byproduct solution was prepared by adding a 25 ml portion of the Na ₂ ⁰ O * - solution adjusted to about 9 ». 5 A greenish, colored copper carbonate precipitate formed. The newly brewed by-product solution, which contained copper carbonate, was heated to the boil for about 15 minutes. After boiling, the by-product solution had a pH of about 8.8 and contained a gray-black precipitate of copper oxide, which could be easily filtered. Both the copper carbonate and copper oxide precipitates contain some minor impurities; the impurities appear to be minor amounts of oxides and copper hydroxide.

Studies show that better results are obtained when 00 is the N _a solution to the aqueous byproduct solution rather than going the other way around. The addition of the aqueous by-product solution to the Na 1 CO 2 solution can cause the formation of a soluble complex during the heating step that converts copper carbonate to copper oxide.

Example 2

To mimic the by-product solution described in Example 1, a "synthetic" aqueous acidic solution was used manufactured. A typical synthetic approach using the aqueous acidic by-product stream described in Example 1 was, comes very close, was made as follows,

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Docket 41_,

A flask was exposed to a 9352 ml portion of water and a 2540 ml portion of HGl (concentration: 37.5% by weight). An 187 g portion of GuGl ₂ , a 1161 g portion of NaCl and a 604 ml portion of BUSO ^, (concentration: 96% by weight) were added to the flask. The mixture in the flask was then chlorinated by _{bubbling Gl 2} -GaS through the flask. A total of 85 g of Gl _{2 were} added. The synthetic, acidic by-product solution contained 6.8098 g of copper ions per liter of solution.

The "synthetic" solution was treated as described in Example 1 to produce a copper carbonate precipitate and convert the copper carbonate precipitate into copper oxide. The copper oxide precipitate came off easily filter.

Comparative procedure A

For comparison purposes, but not in accordance with the procedure of present invention, has been using the effect of neutralizing the aqueous acidic by-product solution a caustic potash solution determined.

The aqueous acidic by-product solution prepared as described in Example 1 was prepared according to the following Neutralized procedure: A 375 ml portion of the by-product solution was placed in an ice bath and the ρΉ value was by adding a 70 ml portion of 50 wt.% NaOH, which was added over about 2 minutes, adjusted to about 10.8; the temperature of the reaction mixture rose to about 72 ° C. Green solids that formed were difficult to filter. The filtration of approximately 530 ml using a Buchner filter over 2 hours. The solids looked more like a slimy precipitate than a solid precipitate. Of the "Precipitate" was dried overnight and analyzed.

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The analysis showed that 42.1% by weight of copper was present. It was "determines that the" precipitate "is predominantly copper hydroxide which contained oxide impurities.

A study was carried out to more carefully examine the relationship between the pH of an excess ion By-product solution and the formation of a copper hydroxide precipitate to describe.

An acidic solution containing copper ions was prepared, by dissolving CuC ^ in an aqueous HCl mixture became. The solution containing copper ions was washed with a 0.49N NaOH solution titrated, and the pH was plotted against the amount of NaOH added as a curve. At a pH of about 3 a pale, cloudy solution formed. The pH gradually rose from about 1/2 to about 1 1/2 Add the first 8 ml of NaOH solution and then rapidly to about 3 1/2 with the addition of the next 2 ml of NaOH. The next 33 ml NaOH caused the pH to rise slowly to about 4.5, while the next 5 ^ l caused a rapid increase to about 11 3/4.

A two-step, batch procedure was performed to determine if removal of copper ions from an acidic by-product solution by adding both NaoCO and NeOH are possible.

Example 3

An acidic by-product solution which, as described in Example 1, was prepared, was neutralized according to the following procedure: The pH of a 25 ml portion the acidic by-product solution was adjusted to about 3/4 by adding an 18.3 ml portion of 4.78N NaOH. Of the pH was kept at such a level that the solution adapts to the limit of the formation of a copper hydride

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Docket 4-1

Precipitation was found, as shown by the pH curve discussed above, which had been obtained by plotting the pH against the amount of NaOH added. A 6.2 ml portion of a 7.2N NapCO ₅₅ solution was added to the mixture to raise the pH from about 5 to about 9.7. A pale blue slurry formed. When the slurry was heated to boiling, an easily filterable, brown-black precipitate formed.

A 1-stage, discontinuous procedure was tested in order to investigate the neutralization of an acidic by-product stream with a mixture of NaOH and Na ₂ CO.

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An acidic by-product solution, which had been prepared as described in Example 2, was neutralized according to the following procedure: A solution of a mixture of NaOH and NapCO was prepared by adding a 1855 ml portion of 4.785N NaOH and a 620 ml Portion of 7.2 ⁰ ^ n-Na ₂ ⁰ O ₅ were mixed together. The mixed base solution was then used to titrate a 25 ml portion of the "synthetic" acidic solution described in Example 2. After a total of 16.05 ml of base solution had been added to the "synthetic" acidic solution, the formation of a precipitate was observed. The pH was about 2.3 · Total 17 ^"2 * · used nil base solution to the" synthetic "solution to pH to titrate 9j7. The reaction mixture was then heated and was observed to turn black upon reaching a temperature of 80 ° C. The reaction mixture was cured at this temperature for 5 minutes; it was easy to filter.

For reasons of expediency and economy, a continuous process takes place over a discontinuous one Working method preferred.

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Example 5

A first 150 ml Bec3aer and a second 200 ml beaker were connected by an overflow tube. The 200 ml beaker was then connected to a collection bottle. The first beaker had separate feed lines for charging 7.29N Na2 ^Co z ^and a 4N acidic by-product solution. The 200 ml beaker was equipped with a stirrer and a heating mantle.

In operation, vacuum was applied to keep a flow out of the to cause the first cup through the tube into the second cup. The level in the second cup was regulated so that that there was an average residence time of 3 hours after which the neutralized slurry was removed from the second cup flowed into the collection bottle.

A 93.7 ml portion of 7.29N Na ₂ CO., Solution and a 156.25 ml portion of the acidic by-product solution were mixed together (pH 8.7) · A 4-5 ml portion of the resulting Slurry was added to the first beaker and the remaining slurry was added to the second beaker. The slurry in the second beaker was heated to and held at about 90 ° C, after which 2.083 ml portions of Na ₂ CO * and 3 * 4-7 M portions of the acidic by-product solution were added to the first beaker every 5 minutes . The pH of the mixture in the first beaker was maintained at about 8.4 to 8.7. After about 3 hours, the slurry from the second beaker was cooled and drawn into the collection bottle. The gray-black reaction mixture in the collecting bottle, which contained copper oxide, could be easily filtered.

It can be understood that the aqueous by-product stream identified above is inherently highly acidic. Copper-

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Carbonate has minimal solubility at a pH of around 9 and is soluble in aqueous acids. As a result of this it is discussed in relation to the precipitation of the copper cations standing by-product bromine as copper carbonate necessary to neutralize the acid and for a final pH of about 9, for example from 8 to 10 and preferably from

8 1/2 to 9 1/2 to worry. This essentially means a double titration, namely (1) the acid and (2) the des Vaccine salt. Although the copper cations act as carbonate mere addition of a suitable carbonate salt, such as sodium carbonate, can be precipitated to the by-product stream, one preferably uses a combination of a base, such as sodium oxide or hydroxide, and a carbonate salt to precipitate the copper carbonate. For example sodium carbonate has a molecular weight of about 106 while sodium hydroxide has a molecular weight of 40. Because finally pH obtained after precipitation of the copper carbonate about

9 is the equivalent weight of the sodium carbonate its molecular weight because of sodium bicarbonate when titrated to a pH of about 9 its Final shape is. Accordingly, 1 kg of sodium hydroxide is equivalent to more than 2 1/2 kg of sodium carbonate. It was found, that copper hydroxide from a by-product stream of the in question The coming species begins to precipitate when its pH value exceeds about 3 * 5. In light of the above Discussion it is understandable that a preferred method for precipitating a copper carbonate from an acidic, aqueous By-product stream according to the present invention therein consists in adding a combination of sodium oxide or hydroxide and sodium carbonate to the same. This can be sequential done in either a batch or a continuous reaction by initially with sodium oxide or hydroxide to a pH value not exceeding about 3 »5 and then with sodium carbonate up to one pH value of about 9 is titrated, or it can also be done in a single step by adding to the titration.

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act, both sodium hydroxide or oxide and sodium carbonate be added in suitable proportions. The two-stage titration is used for a continuous Operation preferred because the process is based on pH determinations can be checked without the need to determine the proportions from time to time, in which sodium oxide or hydroxide and sodium carbonate are required.

In practice it is used for the production of copper carbonate for reasons of availability and economy Sodium carbonate the preferred reactant. It goes without saying that equivalent results using potassium carbonate or even lithium corbonate, rubidium carbonate or cesium carbonate can be achieved, but the cost is prohibitive would be.

When choosing a base to neutralize the excess There is more acidity in the by-product stream Margin if, as is preferred, sodium carbonate is not used for this purpose. For example, was an excess of calcium carbonate was added to the "synthetic", aqueous, acidic solution described in Example 2. It has been found that the highest pH value is achieved by the reaction between the solution and the calcium carbonate could be achieved, was about 7. However, when the reaction product is heated to about 80 ° C and treated with sodium carbonate until the pH was titrated to about 9, a black, easily filterable copper precipitate quickly formed with no apparent contamination from reprecipitated calcium carbonate. Potassium oxide or hydroxide can also used to neutralize excess acid, as well as lithium, rubidium and cesium oxide and hydroxide, however, with the aforementioned economic disadvantages. Calcium and magnesium oxide and hydroxide can also neutralize the acidity level in the by-product stream

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will; Ammonium cations should, however, be avoided because copper is present instead of the insoluble copper carbonate of ammonium cations forms a soluble complex ".

It is understandable that the ideal ecological solution to any given pollution problem is not only consists in the polluting substance in question - in the case of the present. Invention of copper - from wastewater, before discarding it, but also in recycling the polluting substance. It was found that the easily filterable copper oxide precipitate, which is formed as described in Example 1, not only easily separated from the aqueous by-product stream, but also after separation, for example in hydrochloric acid, can be easily dissolved. the The resulting copper chloride solution can then be used in the practice of the method briefly described above can be reused to make more sulfonyl chloride.

As indicated above, in the chlorination step described in Example 1, copper (I) ions are in the by-product stream converted into copper (II) ions. It has been found that such a conversion is not necessary if only a separation of copper from the by-product stream is desired. For example, example 1 can be omitted with the Chlorination step can be repeated, and an easily filterable copper oxide precipitate can be produced represents a mixed copper (I) -copper (II) oxide. However, the resulting precipitate was found to be at best is sparingly soluble in hydrochloric acid. Accordingly When practicing the process according to the invention, preference is given to the copper ions in the aqueous Convert the by-product stream into the copper (II) state, to precipitate a copper carbonate in which the copper cations are are in the copper (II) state, and the low

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beat, as discussed earlier, into an easily filterable one Convert form in which the Zupferkationen in the copper (II) state are present.

The above examples illustrate the practical implementation of the recovery process of the present invention of copper from aqueous, acidic by-product streams, In addition to copper, the main metal cations are sodium and calcium. As stated above, lets the separation of copper from these cations can be easily accomplished and a copper precipitate can be produced that is easily convertible into a reusable form. The same applies to by-product streams, which contain other alkaline cations or other alkaline earth cations. Where it is desired, copper for recover reuse from a by-product stream, which contains metal cations which are precipitated together with the copper according to the process of the invention, the combined precipitate can be separated from the by-product stream and copper can be recovered therefrom by the combined precipitate with an aqueous ammonia-ammonium carbonate solution is leached at elevated temperature (see US Pat. No. 3,647,423).

The heating step according to the invention for converting the copper carbonate into an easily filterable precipitate is carried out, as can be understood, in a short period of time, for example in a few minutes at temperatures between about 90 ° C and the boiling point, although prolonged heating is not harmful will. The conversion can also take place at lower temperatures, but at which longer times are necessary be accomplished. In general, the use of temperatures below about 70 ° C has not been found to be practical proven.

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It has been found that the method according to the invention is carried out in such a practical manner under laboratory conditions it can be that 99 »9 wt.% copper from aqueous, acidic By-product streams are recovered, and that under

Conditions such as those found in factories, a copper recovery of over 95% by weight can be achieved.

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Claims (7)

Docket 41 27. j _u ii Claims Process for recovering copper from an aqueous acidic by-product stream that also contains other metal cations contains dissolved as copper, characterized in that the copper cations are contained in said stream precipitates as copper carbonate, the said stream and that precipitated copper carbonate is heated to a sufficiently high temperature long enough to release the copper carbonate to convert into an easily filterable precipitate, and the precipitate is separated from said stream. 2. The method according to claim 1, characterized in that said aqueous stream is first added by adding partially neutralized by NaOH to a pH value not exceeding about 3.5 and then the copper carbonate through Addition of sodium carbonate to the partially neutralized aqueous stream precipitates. 3 · The method according to claim 2, characterized in that the partially neutralized, aqueous stream, before adding sodium carbonate to it, to a temperature heated to at least 70 ° C. 4. The method according to claim 2, characterized in that the addition of sodium carbonate is regulated so that for a final pH of 8 to 10 is ensured. 5. The method according to claim 4, characterized in that the addition of sodium carbonate is regulated so that a final pH of 8 1/2 to 9 1/2 is ensured will. 6. The method according to claim 1, characterized in that the aqueous by-product stream organic pollutants - 14 409807/0855 Contains substances and one has the copper cations in the by-product stream first oxidized to the copper (II) state and then a reduction of the copper (II) cations prevented. 7. The method according to claim 2, characterized in that the first partial neutralization is carried out by a stream of sodium hydroxide solution is poured into a stream of the aqueous, acidic by-product lets the resulting mixed stream flow into a collecting vessel, which is made by additions of sodium carbonate is kept at a pH of about 8 1/2 to 9 1/2, and that the contents of the Collecting vessel at a temperature of at least about Holds 80 ° C. - 15 - 409807/0855