US20070207076A1

US20070207076A1 - Method of preparing metal-containing wood preserving compositions

Info

Publication number: US20070207076A1
Application number: US11/367,443
Authority: US
Inventors: Joseph Guzzetta; Mark Przybylski; Jun Zhang
Original assignee: Osmose Inc
Current assignee: Osmose Inc
Priority date: 2006-03-06
Filing date: 2006-03-06
Publication date: 2007-09-06

Abstract

The present invention relates to a method for producing metal-containing amine solutions by reacting a metal or metal-containing compound, in particular, copper or a copper-containing compound, with an amine, carbon dioxide and an oxidizing agent. The resulting metal-amine solution can then be used to formulate a variety of metal-based wood preserving products.

Description

TECHNICAL FIELD OF INVENTION

The present invention relates to methods of preparing copper-containing aqueous solutions.

BACKGROUND OF THE INVENTION

Wood preserving compositions are well known for preserving wood and other cellulose-based materials, such as paper, particleboard, textiles, rope, etc., against organisms responsible for the destruction of wood, namely fungus and insects. Many conventional wood preserving compositions comprise copper amine complexes. Copper amine complexes have been used in the past because the copper when in such complexes become soluble in aqueous solutions. The copper in such copper amine complexes is obtained from a variety of copper-containing materials, such as copper scrap, cuprous oxide, copper carbonate, copper hydroxide, a variety of cuprous and cupric salts, and copper-containing ores. The amine in such copper amine complexes is normally obtained from an aqueous solution of ammonia and ammonium salts, such as ammonium carbonate, and ammonium sulfate.
U.S. Pat. No. 4,622,248 describes forming copper amine complexes by dissolving copper oxide in ammonia in the presence of ammonium bicarbonate.
Some of the first experiments with ammonia and copper-containing ore were carried out at Federal Lead Company, Flat River, Mont., in the early 1900's. The ore was leached by percolation with ammonia and ammonium bicarbonate solutions to form various cupric-ammonium compounds. The copper-ammonia solution was separated from the ore and heated with steam to remove both the ammonia and carbon dioxide and precipitate the copper as cupric oxide. The removed ammonia and carbon dioxide may be collected and recycled.
U.S. Pat. No. 5,492,681 disclose processes to produce cupric oxide dissolving copper-containing materials with aqueous ammonia and an ammonium salt in the presence of oxygen to form a cupric amine compound. Upon heating, the cupric amine compounds decompose to cupric oxide, ammonia and water.
Copper amine complexes may also be produced by substituting an amine for ammonia to dissolve the copper-containing material. The reaction rate for forming such metal, in particular, copper amine complexes is not favorable and, therefore, the process is very time consuming, as shown in Table 1, which will be discussed in greater detail below.

SUMMARY OF THE INVENTION

The present invention provides methods for producing metal-containing solutions. In a preferred embodiment, a metal or metal-containing material, amine, carbon dioxide and an oxidizing agent are provided, combined to produce an aqueous solution that promotes the dissolution of the metal. The resulting metal amine solution can then be used to formulate a variety of metal-based wood preserving products. In a preferred embodiment, the metal is copper metal. In another preferred embodiment, the metal-containing material is cuprous oxide.
The present invention provides a method for dissolving copper or a copper-containing material comprising the steps of mixing copper or a copper-containing material, water, amine, carbon dioxide in an amount less than about 5% by weight, and an oxidant such that the aqueous solution contains between about 5 and about 12% dissolved copper within 5 hours. In one embodiment, the carbon dioxide is present in an amount less than about 4%, 3%, or 2%. In another embodiment, the methods of the present invention provide dissolution rates where the aqueous solution contains between 1 and 20%, 2 and 20%, 3 and 20%, 4 and 20% 5 and 20%, 6 and 20%, 7 and 20%, 8 and 20%, 9 and 20%, 10 and 20%, 11 and 20%, 12 and 20%, 13 and 20%, 14 and 20%, 15 and 20%, 16 and 20%, 17 and 20%, or 18 and 20% dissolved copper per hour. In another embodiment, the methods of the present invention provide dissolution rates where the aqueous solution contains about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20% dissolved copper per hour.
The present invention also provides a method for dissolving copper or a copper-containing material comprising the steps of mixing the copper or a copper-containing material, water, amine, carbon dioxide, and an oxidant such that the aqueous solution contains between about 5 and about 12% dissolved copper within 5 hours. In another embodiment, the methods of the present invention provide dissolution rates where the aqueous solution contains between 1 and 20%, 2 and 20%, 3 and 20%, 4 and 20% 5 and 20%, 6 and 20%, 7 and 20%, 8 and 20%, 9 and 20%, 10 and 20%, 11 and 20%, 12 and 20%, 13 and 20%, 14 and 20%, 15 and 20%, 16 and 20%, 17 and 20%, or 18 and 20% dissolved copper per hour. In another embodiment, the methods of the present invention provide dissolution rates where the aqueous solution contains about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20% dissolved copper per hour.
The present invention also provides a method for dissolving copper or a copper-containing material comprising the steps of mixing the copper or a copper-containing material, water, an amine, and carbon dioxide, and introducing an oxidant to the solution at an air at flow rate of between about 0.5 and 100 standard cubic feet per hour (SCFH). In one embodiment, the oxidant is introduced at an air flow rate of between 0.5 and 10, 0.5 and 20, 0.5 and 30, 0.5 and 40, 0.5 and 50, 1 and 5, 1 and 10, 1 and 20, 1 and 30, 1 and 40, 1 and 50, 2 and 10, 2 and 20, 2 and 30, 2 and 40, 2 and 50, 5 and 10, 5 and 20, 5 and 30, 5 and 40, 5 and 50, 10 and 20, 10 and 30, 10 and 40, 10 and 50, 10 and 60, 10 and 70, 10 and 80, 10 and 90, 10 and 100, 20 and 50, 20 and 60, 20 and 70, 20 and 80, 20 and 90, or 20 and 100.
The present invention also provides a method for dissolving copper or a copper-containing material comprising the steps of mixing the copper or a copper-containing material, water, amine, carbon dioxide, an oxidant and an and a quaternary ammonium compound in an amount sufficient to produce a rate at least 1.5-, 2-, 5-, or 10-fold of that rate observed in the absence of the quaternary ammonium compound. In another embodiment, the surfactant is in a concentration sufficient to produce a metal-amine solution at a rate at least 50% greater than that observed in the absence of the surfactant.
The present invention also provides a method for dissolving copper comprising the steps of mixing the copper, water, between about 40 and about 50% monoethanolamine (by weight), carbon dioxide in an amount less than about 5% by weight, an oxidant and a quaternary ammonium compound such that the aqueous solution contains between about 5 and about 12% dissolved copper within 5 hours. In another embodiment, the methods of the present invention provide dissolution rates where the aqueous solution contains between 1 and 20%, 2 and 20%, 3 and 20%, 4 and 20% 5 and 20%, 6 and 20%, 7 and 20%, 8 and 20%, 9 and 20%, 10 and 20%, 11 and 20%, 12 and 20%, 13 and 20%, 14 and 20%, 15 and 20%, 16 and 20%, 17 and 20%, or 18 and 20% dissolved copper per hour. In another embodiment, the methods of the present invention provide dissolution rates where the aqueous solution contains about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20% dissolved copper per hour. In one embodiment, the monoethanolamine is present in an amount between about 45 and 50%, between about 47 and 50% or between about 48 and 50%.
The present invention also provides a method for producing a metal amine solution, comprising the steps of: mixing a water-insoluble metal or metal-containing material, water, an amine, an oxidizing agent and a surfactant in a concentration sufficient to produce a metal-amine solution at a rate at least 1.5-, 2-, 5-, or 10-fold that observed in the absence of the quaternary ammonium compound. In another embodiment, the surfactant is in a concentration sufficient to produce a metal-amine solution at a rate at least 50% greater than that observed in the absence of the surfactant.
The methods of the present invention may be used to dissolve a variety of metal-containing materials and metals, including copper, aluminum, iron, lead, tin, cadmium, nickel, chromium, and zinc. In a preferred embodiment, the metal is copper. In a preferred embodiment, the metal-containing material is a copper-containing material. In a more preferred embodiment, the copper-containing material is cuprous oxide.
The methods of the present invention provide dissolution rates where the aqueous solution contains between about 5 and about 12% dissolved copper within 5 hours. In a more preferred embodiment, the methods of the present invention provide dissolution rates where the aqueous solution contains between about 5 and about 12% dissolved copper within 3 hours. In the most preferred embodiment, the methods of the present invention provide dissolution rates where the aqueous solution contains between about 5 and about 12% dissolved copper within 1 hour. In another embodiment, the methods of the present invention provide dissolution rates where the aqueous solution contains between 1 and 20%, 2 and 20%, 3 and 20%, 4 and 20% 5 and 20%, 6 and 20%, 7 and 20%, 8 and 20%, 9 and 20%, 10 and 20%, 11 and 20%, 12 and 20%, 13 and 20%, 14 and 20%, 15 and 20%, 16 and 20%, 17 and 20%, or 18 and 20% dissolved copper per hour. In another embodiment, the methods of the present invention provide dissolution rates where the aqueous solution contains about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20% dissolved copper per hour.
Each of the methods of the present invention may also employ the use of a surfactant. In one embodiment, the surfactant is a non-ionic surfactant. In another embodiment, the surfactant is an anionic surfactant. In yet another embodiment, the surfactant is a cationic surfactant. Preferably, the cationic surfactant is a quaternary ammonium compound. In a preferred embodiment, the cationic surfactant is a quaternary ammonium compound. In a preferred embodiment, the quaternary ammonium compound has the following structure:

wherein R₁, R₂, R₃, and R₄are independently selected from alkyl or aryl groups and X⁻selected from chloride, bromide, iodide, carbonate, bicarbonate, borate, carboxylate, hydroxide, sulfate, acetate, laurate, or any other anionic group. In a more preferred embodiment, the quaternary ammonium compound is n-alkydimethyl benzyl ammonium chloride, alkyldimethylbenzylammonium chloride, alkyldimethylbenzylammonium carbonate/bicarbonate, dimethyldidecylammonium chloride, didecyl dimethyl ammonium chloride, or dimethyldidecylammonium carbonate/bicarbonate. Most preferably, the quaternary ammonium compound is (C₁₂-C₁₈) dimethylbenzylammonium chloride or Q-5097.
In a preferred embodiment, the surfactant is a low-foaming surfactant. In a more preferred embodiment, the low foaming surfactant is a quaternary ammonium compound. In another embodiment, the low foaming surfactant is Bardac LF, Triton X-100, Triton X-45, an ethoxylated octylphenol, or benzyltrimethylammonium chloride (BTMAC). In another embodiment, the reactions of the present invention may be run with a low-foaming surfactant and a defoaming agent.
In a preferred embodiment, a surfactant is present in an amount between about 0.025 and about 0.250% by weight. Preferably, a surfactant is present in an amount between about 0.050 and 0.250%, 0.100 and 0.250%, 0.125 and 0.250%, 0.150 and 0.250%, 0.175 and 0.250%, and 0.200 and 0.250% by weight. More preferably, a surfactant is present in an amount between about 0.125 and 0.250% by weight. Most preferably, a surfactant is present in an amount between about 0.125 and 0.150% by weight.
Each of the methods of the present invention may also be practiced by introducing the oxidant to the solution at a flow rate of between about 0.5 and about 100 standard cubic feet per hour (SCFH). In one embodiment, the oxidant flow rate is between about 0.5 and 5 SCFH. In another embodiment, the oxidant flow rate is between about 0.5 and about 10 SCFH. In yet another embodiment, the oxidant is introduced at an air flow rate of between 0.5 and 10, 0.5 and 20, 0.5 and 30, 0.5 and 40, 0.5 and 50, 1 and 5, 1 and 10, 1 and 20, 1 and 30, 1 and 40, 1 and 50, 2 and 10, 2 and 20, 2 and 30, 2 and 40, 2 and 50, 5 and 10, 5 and 20, 5 and 30, 5 and 40, 5 and 50, 10 and 20, 10 and 30, 10 and 40, 10 and 50, 10 and 60, 10 and 70, 10 and 80, 10 and 90, 10 and 100, 20 and 50, 20 and 60, 20 and 70, 20 and 80, 20 and 90, or 20 and 100 SCFH.
In the methods of the present invention, the metal or a metal-containing material, water, amine and the oxidant are mixed in a single reaction chamber. In a preferred embodiment, the single reaction chamber is columnar. In another embodiment, the water, amine and the oxidant are mixed in a first reaction chamber and the resulting solution is circulated through copper or a copper-containing material in a second reaction chamber. In one embodiment, carbon dioxide is introduced either in the form of air or as carbon dioxide gas into the solution in the first reaction chamber. Alternatively, carbon dioxide is introduced either in the form of air or as carbon dioxide gas into the solution and copper or copper-containing material in the second reaction chamber. In yet another embodiment, the methods of the present invention may be practiced by adding the carbon dioxide to the solution, either in the first or second reaction chamber, after addition of the copper.
In the methods of the present invention, the amine is selected from the group consisting of any compound that has the following chemical structure:

wherein R1, R2, R3, R4, R5, R6 is independently selected from the group consisting of H,—CH₃,—C₂H₅;—C₂H₄OH

In a preferred embodiment, the amine is monoethanolamine, diethanolamine, ethylamine, diethylamine, dimethylethylamine, dimethylethanolamine, or mixtures thereof. In the most preferred embodiment, the amine is monoethanolamine.
In the methods of the present invention, the solution contains between about 20 and about 60% amine. Preferably, the solution contains between about 30 and about 50% amine. More preferably, the solution contains between about 40 and about 50% amine. In one embodiment, the monoethanolamine is present in an amount between about 45 and 50%, between about 47 and 50% or between about 48 and 50%.
In the methods of the present invention, the oxidizing agent is oxygen, air, ozone, or hydrogen peroxide.
Each of the methods of the present invention may also be practiced by adding a defoaming agent to the solution. In one embodiment, the defoaming agent is a silicon polymer. In another embodiment, the silicon polymer is polyoxylalkylene silicon.
Each of the methods of the present invention may also be practiced by heating the solution to between about 30 and about 100° C. Preferably, the temperature is maintained between about 50° and about 100° C. More preferably, the temperature is maintained between about 50° and about 70° C. Most preferably, the temperature is about 70° C.
Each of the methods of the present invention may also be practiced by adding an acid to the solution. In a preferred embodiment, the acid is carbon dioxide. Preferably, the acid or the carbon dioxide are present in the solution in an amount less than about 5% acid by weight. In one embodiment, the acid is added to the solution prior to addition of the metal or metal-containing material. In another embodiment, the acid is added to the solution after addition of the metal or metal-containing material.
Each of the methods of the present invention may also be practiced by initially adjusting the pH of the solution to between about 9 and 12. Preferably, the pH is initially adjusted to between about 10.5 and about 11.5. In another embodiment, the pH of the solution is maintained between about 10 and 12 by the addition of carbon dioxide. In a preferred embodiment, the pH of the reaction is maintained at about 10.5 and about 11.5. In a more preferred embodiment, the pH of the reaction is maintained about pH 11.
Each of the methods of the present invention may also be practiced by adding an anti-foaming agent, stirring the solution, circulating the solution or conducting the methods of the present invention at pressure greater than 1 atmosphere.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts(a) the effect of a 1% heel on copper metal dissolution rate and (b) the comparative dissolution rates of copper metal and cuprous oxide.
FIG. 2 depicts the effect of a 1% heel on copper metal dissolution rate.
FIG. 3 depicts the effect of a surfactant and antifoam agent on the dissolution rate of cuprous oxide.
FIG. 4 depicts the effect of an air sparge on the dissolution rate of cuprous oxide.
FIG. 5 depicts the effect of an air sparge in the presence of a surfactant on the dissolution rate of cuprous oxide.
FIG. 6 depicts the effect of an air sparge in the presence of a surfactant and antifoam agent on the dissolution rate of cuprous oxide.
FIG. 7 depicts the effect of copper loading on the dissolution rate of copper metal.
FIG. 8 depicts the effect of air flow on the dissolution rate of copper metal.
FIG. 9 depicts the effect of reaction temperature on the dissolution rate of copper metal.
FIG. 10 depicts the effect of liquid flow rate on the dissolution rate of copper metal.
FIG. 11 depicts the effect of heel on the dissolution rate of copper metal.
FIG. 12 depicts the effect of pH on the dissolution rate of copper metal.
FIG. 13 depicts the effect of copper source on the dissolution rate of copper metal.
FIG. 14 depicts the effect of surfactant on the dissolution rate of copper metal.
FIG. 15 depicts the effect of air flow on the dissolution rate of copper metal.
FIG. 16 depicts the effect of pressure on the dissolution rate of copper metal.
FIG. 17 depicts the density profile of a copper-containing solution.

DETAILED DESCRIPTION OF INVENTION

The present invention provides a method for the production of a copper amine solution is provided that efficiently produces the solution at an expedited rate. For purposes of this application, the copper amine solution is obtained from dissolving either copper or a copper-containing compound that is normally insoluble in water.
Any copper-containing material can be used in this process that provides copper amine of the desired purity. In one embodiment, pure metallic copper is used. Impure forms of copper, such as #1 and #2 scrap copper metal, and cuprous oxide can also be used. #1 Scrap copper metal typically contains approximately 99% copper, and #2 scrap metal typically contains approximately 97% copper, but this can vary somewhat among suppliers. #1 Scrap metal is often recycled copper wire that has been stripped of its insulation, and chopped into particles. Scrap metal can include any number of inorganic impurities, including but not limited to aluminum, iron, lead, tin, cadmium, nickel, chromium, and zinc. Scrap metal also sometimes includes organic impurities such as cutting grease. The preferred copper source for this process is cuprous oxide. The use of cuprous oxide is preferred because it greatly enhances the reaction rate of the copper with amine. In addition, cuprous oxide has a large surface area and has a higher oxidation state than copper metal. The use of cuprous oxide as the copper source increases the reaction rate by several fold over that of copper metal, in the form of chopped copper wire, as illustrated in FIG. 1.
Copper metal and copper compounds are normally insoluble in water but can be solubilized in the presence of an amine containing compound with an oxidizing agent (the solution used in Table 1). Although the preferred amine containing compound is monoethanolamine, other amines that can also be used are diethanolamine, ethylamine, diethylamine, dimethylethylamine, dimethylethanolamine, and include any amine that has the following chemical structure:

wherein R₁, R₂, R₃, R₄, R₅, R₆are independently H—, methyl, ethyl, or hydroxy ethyl.
Carbon dioxide may be added prior to or after the addition of the copper metal or copper compound to the composition to adjust the pH of the mixture to about 11.0. However the preferred addition order is prior to the addition of the copper source. The process can be run without the addition of carbon dioxide; however, the dissolution rate of the copper source is reduced significantly.
Any source of oxygen can be used to oxidize copper in this process, as demonstrated in Table I and Charts 1 and 2, pure oxygen, however, is preferred. Air, ozone, and hydrogen peroxide are also suitable sources of oxygen for use in this process providing standard safety precautions are taken for using oxidizing agents in the presence of organic compounds.

TABLE I

Effect of Oxidant Source on Copper Metal Dissolution

Elapsed Time (hours) Temperature (° C.) % Copper in Solution

Oxygen Sparge; 1% Heel

0.00 60 1.23

0.50 68 1.65

1.00 68 2.38

2.25 70 4.57

3.25 70 7.24

4.00 65 8.04

5.25 68 8.36

Air Sparge; 1% Heel

0.00 23 0.90

1.00 65 1.61

2.00 75 2.68

3.00 75 5.04

4.00 75 6.46

5.00 75 7.43

6.00 70 7.94
Process operating pressures can vary from 0 to 100 PSI with the preferred pressure being between 40 to 55 PSI. Operating temperatures can vary from 25° C. to 95° C. with the preferred range being 60° C. to 75° C.
The leach rate of the metals, however, can be enhanced dramatically by the addition into the solution of a small amount of a quaternary ammonium compound such as diethyl dimethyl ammonium chloride, alkyl dimethyl benzyl ammonium chloride, and further enhanced by the further combination with a surfactant compound such as a defoamer, emulsifying agent, foaming agent, and/or silicone polymers. The surfactant compound can be a non-ionic, a cationic or an anionic surfactant. Preferably, the surfactant is a cationic compound. The results of this combination of compounds created a synergistic effect that is illustrated in Table II.

TABLE II

Effect of Surfactant and Antifoam on Copper Metal Dissolution

Elapsed Time (hours) Temperature (° C.) % Copper in Solution

Air Sparge; No Surfactant; No Antifoam

0.00 55 0.00

0.25 65 3.66

0.50 70 5.70

1.00 65 6.06

1.50 65 7.55

2.00 65 8.30

3.25 68 8.95

5.50 68 9.75

Air Sparge; Cationic Surfactant; No Antifoam

0.00 30 0.00

0.50 65 2.52

0.75 72 3.21

1.00 90 4.47

1.25 86 6.99

1.50 82 8.40

1.75 75 8.70

2.25 73 9.12

2.75 71 9.38

Air Sparge; Cationic Surfactant; Antifoam

0.00 60 0.00

0.25 70 4.53

0.50 75 5.79

0.75 74 7.37

1.00 72 8.11

1.25 70 8.90

1.50 69 9.78
A variety of quaternary ammonium compounds can be used in this application. Preferably, the quaternary ammonium compound has the following structure:

where R₁, R₂, R₃, and R₄are independently selected from alkyl or aryl groups and X⁻ selected from chloride, bromide, iodide, carbonate, bicarbonate, borate, carboxylate, hydroxide, sulfate, acetate, laurate, or any other anionic group.
Preferred quaternary ammonium compounds include alkyldimethylbenzylammonium chloride, alkyldimethylbenzylammonium carbonate/bicarbonate, dimethyldidecylammonium chloride, and dimethyldidecylammonium carbonate/bicarbonate. In a most preferred embodiment, the quaternary ammonium compound is (C₁₂-C₁₈) dimethylbenzylammonium chloride.
Preferred aqueous amine solutions of the present invention comprise a quaternary ammonium compound, such as n-alkyldimethyl benzyl ammonium chloride and didecyl dimethyl ammonium chloride, in combination with a defoamer, such as fluoroalkyl phosphate esters, amine oxides and silicone-containing compounds, such as silicone polymers. The preferred defoamers include perfluoroalkylethyl phosphate ester, lauryl dimethyl amine oxide, and dimethicone. Concentrations of the quaternary ammonium compound vary from 0.01-10% with 0.25%-1.0% being the preferred range. Concentrations of silicon polymer can vary from 0.1%-10% with the preferred range being 0.1%-1.0%.
The resulting copper amine solution can be mixed with a variety of biocides such as fungicides and insecticides to produce a formulation suitable for the preservation of wood and other cellulose-base materials. Typical biocides that can be used for this formulation are fungicides such as azoles, quaternary ammonium compounds, and various other conventional insecticides.
Another embodiment of the present invention is a method for preserving and/or waterproofing a wood substrate by contacting a wood substrate with the composition of the present invention. The composition may be applied by any wood treating method known to one of ordinary skill in the art including, but not limited to, brushing, dipping, soaking, vacuum impregnation (e.g. double vacuum technique), and pressure treatment using various cycles.
Modifications and variations of the present invention for a process for the production of aqueous copper amine solutions will be obvious to those skilled in the art from the foregoing detailed description of the invention. Such modifications and variations are intended to come within the scope of the appended claims.

EXAMPLES

The following Examples serve to further illustrate the present invention and are not to be construed as limiting its scope in any way.

Example 1

Preparation of Copper Amine Solution from Cuprous Oxide

A copper amine solution was prepared by combining 530 grams water, 319 grams 99% MEA, 30 grams carbon dioxide, 5 grams N-alkyldimethyl benzyl ammonium chloride, 1 gram fluoroalkyl phosphate ester, and 116 grams cuprous oxide. The mixture was agitated and air was introduced at a rate of 2 SCFH until the concentration of dissolved copper in the solution reached 9.3%. The cuprous oxide mixture was maintained at a temperature of 25° C. throughout the course of the reaction.

Example 2

Preparation of a Copper Amine Solution from Cuprous Oxide

A solution of copper amine applicable for wood preservation was prepared by charging a reactor with 162 grams monoethanolamine and 270 grams water. The pH of the resulting solution was then adjusted to pH 10.95 with carbon dioxide. An initial charge of 2.5 grams alkyldimethyl benzylammonium chloride was added, followed immediately by the addition of 0.05 grams of a fluoro phosphate ester. After mixing, 61 grams cuprous oxide were added to the reactor. The reactor was sealed and pressurized to 65 PSI with air. The reactor was heated to 40° C. and continuously stirred. After the dissolved copper in the solution reached 9.2%, the solution was removed from the reactor and filtered. An additional charge of alkyl ammonium chloride was added to the solution.

Example 3

Preparation of a Copper Amine Solution from Cuprous Oxide

519 grams water were added to a glass reactor at room temperature. A charge equal to 315 grams of ethylamine was then added to the reactor, followed by a charge of 35 grams carbon dioxide. A 0.1 gram charge of a silicone compound was added to the reactor. The solution was mixed and 2.5 grams didecyl dimethyl ammonium chloride were added to the reactor. An oxygen sparge was introduced followed by the addition of 116 grams cuprous oxide. The oxygen sparge was continued and the solution heated to 60° C. The dissolved copper content was allowed to reach 9.4%, at which time the solution was cooled and sparging terminated. The material was filtered and further processed into a wood and cellulose preservative by the addition of cyproconazole and boric acid at levels suitable for the intended application.

Example 4

Preparation of a Copper Amine Solution from Cuprous Oxide

The reactor was charged with 320 grams diethanolamine, 529 grams water, and 6 grams of an N-polymer. The pH of the resulting mixture was adjusted from about pH 13.5 to pH 1.0 by the addition of 20 grams carbon dioxide. 120 grams cuprous oxide were then added to the reactor which was sealed and pressurized to 65 PSI by the injection of oxygen. The temperature of the reactor was maintained at 40° C. and the oxygen injection continued until the dissolved copper content of the solution reached 9.3%.

Example 5

Preparation of a Copper Amine Solution from Cuprous Oxide

The reactor was charged with 322 grams MEA, 530 grams water, 4.8 grams alkyldimethyl benzylammonium chloride and 1.1 grams of a silicone compound. 120 grams cuprous oxide was then added to the reactor. The solution was sparged with air and the temperature maintained at 70° C. until the dissolved copper content of the solution reached 9.3%. Upon dissolution of all the cuprous oxide, carbon dioxide was then sparged into the mixture to reduce the pH from 12.5 to 10. The resulting solution was then mixed with 90 grams alkyldimethyl benzylammonium chloride to form a composition, which is suitable for the preservation of wood and other cellulose materials.

Example 6

Preparation of a Copper Amine Solution from Cuprous Oxide

A copper amine solution was prepared by adding 190 grams monoethanolamine, 320 grams water, 3.1 grams didethyldimethylammonium chloride and 0.8 grams of a silicone compound to the reactor. The composition was agitated until thoroughly mixed and then carbon dioxide sparged into the solution until the pH was reduced from pH 13.7 to pH 11. Once the pH stabilized was at pH 11, 73 grams cuprous oxide were added to the solution and then agitated to form a uniform slurry of cuprous oxide. The reactor was then pressurized to 20 PSI by the injection of oxygen into the slurry. The temperature of the reaction was maintained at 40° C. until the dissolved copper content of the solution reached 9.2%. The solution was filtered to remove any undissolved solids and the resulting solution was then mixed with 2.1 grams cyproconazole and 49.9 grams boric acid to form a product suitable for the preservation of wood and other cellulose-based products.

Example 7

Preparation of a Copper Amine Solution from Copper Metal

A glass kettle reactor was charged with 542 grams water and 323 grams MEA. After allowing the solution to mix for a period of 4 minutes, 33 grams carbon dioxide was sparged into the solution. Following carbon dioxide addition, 5 grams of a quaternary ammonium compound were added along with 0.1 grams of an amine oxide. After two additional minutes of mixing, 97 grams copper metal shot were added to the reactor. The reactor was continuously mixed and heat applied to maintain the temperature at 67° C. A continuous stream of air was sparged into the solution. The dissolved copper content in solution was allowed to reach 9.5%, after which the solution was filtered. The filtered solution was further charged with additional reagents to produce a wood preservative formulation.

Example 8

Preparation of Copper Amine Solution from Copper Metal

A composition containing copper amine was prepared by the addition 317 grams water, 192 grams MEA, 3 grams diethyldimethylammonium chloride, 0.9 grams of an amine oxide, 19 grams carbon dioxide, and 68 grams finely chopped copper wire. The reactor was sealed and oxygen sparged into the reactor at a rate of 4 SCFH. The reactor pressure was maintained at 55 PSI and the temperature maintained at 70° C. until the copper concentration reached 9.2%. The solution was then filtered to remove any undissolved solids and the solution was mixed with 0.09 grams cyproconazole to produce a concentrate suitable for the preservation of wood and other cellulose based materials.

Example 9

Effects of Several Variable on the Preparation of a Copper Amine Solution from Copper Metal

The effect of several variables on the rate of copper metal dissolution, including temperature, air flow, pH, column loading and the amount of surfactant, have been studied. These experiments were conducted in the laboratory using a column constructed of a section of 2″ Sch. 80 PVC pipe. This pipe was flanged and capped at both ends so it could be dismantled easily. A stainless steel screen was placed at the bottom flange to support the copper packing. Heavy “chops” of copper wire were the primary source of copper during the testing. The bottom of the column was tapped twice for liquid and air inlets. The top of the column was also tapped twice for liquid and vapor outlets. A 2-liter glass flask was used to hold the liquid and was heated by an electric heating mantle. Liquid was pumped from the flask to the bottom of the column out the top and back to the flask. The second top outlet was several inches higher than the liquid return and was used to return excess air and foam to the flask if necessary.

The conditions of various reactions (Runs 1-10) are detailed in Table III.

TABLE III


Reaction Conditions for Runs 1-10

			Surfactant	Antifoam	Added
Run	T	MEA	(Q-5097)	(ppm)	CO₂	Heel	Copper	Air F	Const.

No.	(° C.)	(%)	(%)	Initial	Final	(g)	(%)	(%)	(SCFH)	pH

1	50	40	0.25	94	94	—	0	8.2	0-2	No
2	50	40	0.25	94	220	—	<0.05	8.0	2	No
3	70	40	0.25	100	163	—	<0.05	7.1	2	No
4	50	40	0.25	98	485	—	<0.05	8.7	4-5	No
5	50	40	0.25	112	215	16.0	<0.05	8.0	2	No
6	50	55	0.25	100	325	—	<0.05	6.9	2	No
7	50	40	0.125	161	248	—	<0.05	5.8	2	No
8	50	40	0.125	100	149	22.0	<0.05	8.0	2	Yes
9	50	40	0	98	98	27.0	<0.05	6.7	2	No
10	50	40	0.125	84	77	121.5	<0.05	5.6	2	No

Dissolution experiments run under the conditions of Runs 1-10 demonstrate that sparging air directly into the column produced faster rates than sparging into the flask. Elevated temperature and airflow both increased copper metal dissolution rates. High airflow, however, produced undesirable foaming. Initial pH adjustment to pH 11.0, using carbon dioxide, increased dissolution rates. Continuous adjustment of pH to 11.0 produced high densities of the copper-amine solutions, where the solutions contained about 10% dissolved copper. The addition of a surfactant (alkyl (C₁₂-C₁₈) dimethylbenzylammonium chloride (also referred to as QBAC-L, Q-5097, which was supplied as a 50% active solution by Lonza) produced dissolution rates that were faster than those observed when no surfactant was used. Increasing the amount of surfactant from 0.125% to 0.250%, however, had no impact on the dissolution rate of copper metal.

The rates of copper-metal dissolution, using the reaction conditions of Runs 1-10 are summarized in Table IV.

TABLE IV


Dissolution of Copper Metal in Runs 1-10

		Dissolved Copper
	Run	Concentration (%)

	No.	1 hr	5 hr	24 hr

1	0.06	1.88	—
2	0.21	2.59	8.52
3	0.35	4.45	10.12
4	0.15	2.96	—
5	2.52	8.36	11.16
6	0.56	4.10	9.12
7	0.14	2.51	8.49
8	3.23	9.87	>12
9	0.55	7.44	11.13
10	0.72	8.61	>12

The reactor in each of exemplified Runs was filled to 90% capacity with an aqueous MEA solution containing a surfactant (active) and antifoam (active). The antifoam used was Foamtrol WP-155, supplied by Ultra Additives, which was diluted to a 10% active solution prior to use. The pH of this solution was then measured and adjusted down to pH 11 by sparging carbon dioxide through the solution. The solution was then heated to 50° C. prior to initiating the reaction. The airflow was set at 2 SCFH and the liquid flow rate was 600 ml/min at the beginning of each Run. To conform to AWPA Standards, an MEA:copper oxide ratio of 2.75±0.25 was targeted. Accordingly, the final copper amine solution would contain about 10% copper. A typical material balance is shown below in Table V.

TABLE V

Reaction Components

Component Initial Charge (g) Additions (g)

Water 1080.0

MEA 720.0

Quat (50% active) 4.5

Antifoam (10% active) 1.8

CO₂ 27.0 18.0

Copper 208.0

O₂ 52.4

Total 1833.3 2111.7

Example 10

Effect of Adding a Low-Foam Quaternary Ammonium Compound on Dissolution of Copper Metal in an Aqueous Amine Solution

Run 11 used Bardac LF as the surfactant. This is a low foam 50% active Q-5097 supplied by Lonza (dioctyldimethylammonium chloride). Using this quaternary ammonium compound and an airflow of 2 SCFH, no foaming was evident until nearly 24 hours, when some foam was seen emerging out the top vent. Even after 28 hours, no foam accumulation was seen in the flask. Surprisingly, this run was slower than Run 9 which contained no quaternary ammonium compound. On further inspection, it was discovered that the copper level was quite low in comparison to other runs. Most of the earlier runs had a copper level that was 7-8 times the required amount, while this run had just over 4 times that amount.
Run 11 was repeated as Run 12, but using higher copper levels. The results were comparable to Run 5, which used Q-5097 as the surfactant. Foaming was not seen during the first 6 hours, but occurred thereafter. No accumulation of foam was observed in the reactor, however. Because the addition of more copper to the system had a positive effect on the rate, the copper column was replenished to a level 7-8× the required amount following each run after Run 12. A new phenomenon that occurred during these two runs was a large accumulation of solid residue on the walls of the glass reactor above the operating liquid surface. ICP analysis showed that these were over 77% copper with small amounts (˜200 ppm) of iron and aluminum.
For Run 17, the liquid return was changed so that it returned sub-surface in the reactor. This was done in an attempt to minimize the amount of solids seen on the walls following several of the runs. The largest amounts of solid deposition were seen in Runs 11 and 12 using Bardac LF, which was again used as the surfactant in Run 17. The concentration profile in this run was very similar to Run 12; the only difference being the amount of copper in the column (7.3× vs. 8.0×). The foaming level was also similar in that foaming was seen in the vapor return, with very little accumulation in the reactor. The change in liquid return did not effect solid deposition, as solids again coated the reactor walls following the reaction. Following Run 17, the liquid return was relocated to return above the liquid surface.

Example 11

Effect of Air-Flow Rate on Dissolution of Copper Metal in an Aqueous Amine Solution

A few of the previous runs had shown that early in the reaction, when the rate was maximized, nearly all of the available oxygen was being consumed. At this scale, using an air flow of 2 SCFH, the copper dissolution rate was about 3.3%/hour at full oxygen consumption. To investigate this further, Run 13 used an air flow rate of 4 SCFH. Because foaming was expected at this airflow rate, conditions similar to Run 10 were used, including an initial pH of 9.5, because very little foaming had been observed during Run 10. Run 13 started relatively slow, but the rate increased rapidly after 1-2 hours, reaching 10% dissolved copper in about 4.5 hours. The maximum dissolution rate during the run was 4.4%/hour, demonstrating that higher reaction rates could be achieved with higher airflows. Throughout the run, foam flowed from the top vent of the column back to the reactor. Accumulation in the reactor was minor, though, never reaching more than 1-2 inches.

Example 12

In Run 14, the reaction was completed in less than 4 hours. This reaction was run at 70° C., with 4 SCFH airflow and continuous pH adjustment. This run reached 10% copper in 3.25 hours. The dissolution rate was within the first hour was measured at 6.6%/hour. This corresponds to nearly complete oxygen consumption. The foam levels in this run were similar to Run 13. Substantial amounts of foam were returned by the overhead vent, but the accumulation was only 1-2 inches.

Example 13

Effect of Liquid Flow Rate on Dissolution of Copper Metal in an Aqueous Amine Solution

The effect of liquid flow rate was studied in Runs 15 and 16. For Run 15, the liquid flow rate was 200 ml/min, while Run 16 had a liquid flow rate of 1075 ml/min. All previous runs had been performed at flow rates of 600 ml/min. The results indicate a slight dependence on liquid flow rate.

Example 14

Effect of Heel on Dissolution of Copper Metal in an Aqueous Amine Solution

Generally, the column is flushed 3 times with water prior to the next run. For Run 18, the reactor and column were not cleaned prior to start-up. Run 18 started with a 0.43% heel. This was done for two reasons: 1) to see the effect on the rate by essentially starting with a “heel” and also to see if the solids deposited on the walls of the reactor during Run 17 would dissolve. The presence of the heel did have a positive effect on the rate as the system reached 10% copper in under 6 hours. The observed rate was near maximal from the start of the reaction and remained high for the first 2 hours. Throughout the run, foam was again seen in the vapor outlet with very little accumulation in the reactor. During the carbon dioxide addition, it appeared as if about 15-20% of the material on the reactor walls dissolved. Following the reaction, the amount of solids on the walls was about the same as the previous run, so there was no additional accumulation.

Example 15

Effect of Quaternary Ammonium Compounds and Maintaining Constant pH on Dissolution of Copper Metal in an Aqueous Amine Solution

Run 19 was run with no surfactant. pH was monitored and continuously adjusted to about pH 11. The profile of this run was well short of Run 8 which was operated under identical conditions, except with the addition of 0.125% quaternary ammonium compound. This demonstrates that although constant pH is a large factor in the rate, some surfactant is still necessary to maximize the rate. Without surfactant, Run 19 exhibited no foaming. After running overnight, there was again a film on the walls which was not present after 7 hours.
Run 20 was run with a reduced amount of surfactant to improve the dissolution rate (compared to Run 19) while maintaining the foam level at a minimum. To enhance the dissolution rate, “heel” was again present. The pH was also adjusted throughout the run. Run 20 started at a moderate rate, but did not reach its maximum rate until about 2 hours. Although the overall reaction was fast, reaching 10% Copper in 5 hours, it appears that more surfactant may be necessary to maximize the initial rate.

Example 16

Effect of Copper Metal Source on Dissolution Rates in an Aqueous Amine Solution

Unlike “chops” which are somewhat homogeneous in size, shredded copper comes in all shapes and sizes, from very fine wire (˜ 1/32″) to large tubing (˜1″) and all sizes in between. Pieces can be straight, bent, flattened or bundled, depending on the copper source and how each particular piece went through the shredder. For the next few runs, a comparison was made between the dissolution rates observed between shredded copper and copper chops.
Shredded copper was used for Run 22. Since the shredded copper is inconsistent in shape and size, it does not pack the column as well as the chops. In packing the entire column, only 2.1 times the required amount of copper was charged. This is much less than the 7-8× copper loading that may be achieved using copper chops. Run 22 was run at 50° C., 2 SCFH airflow and a single pH adjustment prior to the start of the run. Run 22 started very slowly, but had a good rate in the 3-5 hour range, eventually reaching 10% copper after about 15 hours. After several hours, foam was seen in the vapor outlet, but there was no accumulation in the reactor.
For Run 23, the column was emptied of the shredded copper and charged with an identical amount (2.1×) of copper chops. Run 23 was run using the same conditions as Run 22. This run was much slower and did not reach 10% copper until 22 hours. This is most likely due to differences in surface area. Even though there were large pieces of tubing in the shredded copper, the overall surface area may have been greater because of the bundles of fine wire. Foaming was about the same as in Run 22. Samples of the final solutions and of the solids from each of these runs were submitted for metals analysis.
Run 24 was run with 1.6 times the required amount of shredded copper. Run 24 was run at an airflow of 4 SCFH while continuously adjusting the pH with carbon dioxide. The results of this run were similar to that of Run 22 (shredded copper), except that it had a slower start and ran 1-1½ hours behind. More foam was generated in the vapor outlet due to the higher airflow, but there was still very little accumulation in the reactor. No solids were seen on the walls of the reactor at shutdown (6 hours, 5.6% Copper).

Example 17

Effect of Surfactant on Dissolution Rates in an Aqueous Amine Solution

Due to the foaming caused by the presence of Q-5097, other potentially low-foaming surfactants and their effect on the dissolution rate were examined. Operating conditions for several of these runs are listed in Table VI (Q-5097 runs (Run 5 and 27) are included for comparison). Each reaction was run at 50° C. and at an air flow of 2 SCFH.

TABLE VI


Effect of Surfactant Type on Copper Metal Dissolution Rates

			Copper
Run	Copper		Concentration (%)

No.	Loading	Surfactant	1 h	5 h	24 h

17	7.3	0.125% Bardac LF	3.5	9.6	>12
21	6.9	0.125% Triton X-100	1.0	8.2	—
25	7.2	0.125% BTMAC	1.6	7.8	11.3
26	7.2	0.125% Triton X-45	2.5	8.0	11.2
27	7.2	0.125% Q-5097	3.4	9.3	—
5	8.0	0.25% Q-5097	2.5	8.4	11.2
9	6.7	None	0.6	7.4	11.1

Run 17, using Bardac LF, was found to produce results similar to Q-5097 (Run 5). Run 21 used Triton X-100 (Union Carbide/Dow), a common nonionic surfactant, as the surfactant. Triton X-100 is an ethoxylated octylphenol, which is much different than the quaternary ammonium structures of Q-5097 and Bardac LF. Run 25 used benzyltrimethylammonium chloride (BTMAC), which is a quaternary ammonium compound with a structure similar to Q-5097, except the C₁₂-C₁₈group is replaced by a third methyl group. Run 26 used Triton X-45 (Union Carbide/Dow), another nonionic surfactant with fewer ethylene oxide units in its structure than Triton X-100. Run 27 used Q-5097 under identical operating conditions as the previous runs. In the results shown above, the fastest rates were observed under the conditions of Run 27, using Q-5097. Run 27 outperformed Run 5, which used 0.250% Q-5097.
Each surfactant produced a rate enhancement compared to reactions run with no surfactant. None of the surfactants, however, showed the rate-enhancing ability that was seen with Q-5097. The primary reason for investigating a variety of surfactants was not rate enhancement but foam control. Reactions run with Q-5097 produced several inches of foam and required addition of antifoam. Run 17 (Bardac LF) generated foam in the vapor outlet, but there was no accumulation of foam in the reactor. The other surfactants produced no foam. Run 26 (Triton X-45) was run without anti-foam and still generated no foam. All of these runs left some amount of brown residue on the walls of the reactor.

Example 18

Effect of Carbon Dioxide on Dissolution Rates in an Aqueous Amine Solution

The initial pH of the aqueous MEA solutions varied widely from about pH 12.2 to pH 13.0. Runs at the lower values (12.2-12.6) generally required 15-30 grams carbon dioxide to reach a pH of 11, while runs at the higher values (12.9-13.0) required 40-50 grams carbon dioxide to reach pH 11. Examination of the carbon dioxide concentration profiles for these runs revealed a correlation between the initial copper dissolution rates and the mount of carbon dioxide initially in the reaction. Specifically, the runs exhibiting the fastest initial dissolution rates have the least carbon dioxide added (15-30 g). Runs containing relatively lower amounts of carbon dioxide, however, slowed more quickly, whereas runs containing relatively greater amounts of carbon dioxide (i.e. slower initial rates) reached total conversion (10% Copper) more quickly. Based on this observation and the observed rate enhancements achieved from maintaining the pH of the reactions constant, the copper dissolution rate may be optimized by initially adding 25-30 g carbon dioxide (˜1.5% by weight of the MEA/water charge) followed by continuous adjustment of the pH as the run progresses.

Example 19

Effect of Various Surfactants on Dissolution Rates in an Aqueous Amine Solution

The effect of low initial carbon dioxide loads (˜1.5% by weight of the MEA/water charge) followed by continuous pH adjustment with carbon dioxide was examined using low-foaming surfactants. Conditions for these runs (Runs 28-31) are listed in Table VII. The conditions for

Runs

8 and 14 are listed for comparison. For each run, the pH was adjusted with carbon dioxide by adding 25-30g carbon dioxide initially and then adjusting the pH as necessary throughout the run.

TABLE VII


Effect of Surfactant Type on Copper Metal Dissolution Rates

Run	Temp	Air Flow	Copper	Initial
No.	(° C.)	(SCFH)	Loading	CO₂(g)	Surfactant

28	50	8	7.3	27	0.125% Triton X-100
29	70	8	7.3	26	0.125% Triton X-100
30	70	8	7.3	26	0.125% Bardac LF
31	70	8	7.3	26	0.125% Triton X-100*
8	50	2	8.0	22	0.125% Q-5097
14	70	4	7.4	19	0.125% Q-5097

*incremental addition

Bardac LF was used as the surfactant in Run 30. This run reached 7% copper in the first hour and 10% copper in 2.67 hours. As the reaction progressed, foaming occurred out the vapor outlet; however, the foam level in the reactor was insignificant after 3 hours and was only 1-2 inches after 5 hours. It is expected that one or two additions of antifoam during the run would cause the foam to subside completely.
The rates observed for Runs 28 and 29, which used Triton X-100 as a surfactant, were nearly identical even though there was a 20° C. temperature differential. Because Run 14 and Run 30 exhibited more rapid dissolution rates than Runs 28 and 29, it was suspected that Triton X-100 may have degraded during the reaction. Run 31 was conducted to test this suspicion. In Run 31, 0.05% Triton X-100 was added initially with hourly additions of 0.025% for the first three hours. No rate enhancement was observed and the results of Run 31 were nearly identical to Runs 28 and 29. From these results, it appears that Triton X-100 is either breaking down or does not have the rate-enhancing abilities observed for the other quaternary ammonium surfactants.
Another item to note is that for Runs 28-31, each run began at its maximum rate, ranging from 5.1% to 9.2% dissolved copper per hour. These rates were determined by noting the change in concentration between the first two samples, generally taken at 5 min and 30 min. In all previous runs, the maximum rate was reached at later time points. Thus, it appears that an initial addition of 1.5% carbon dioxide by weight (based on MEA/water) may indeed help to maximize the initial rate.

Example 20

Solid Deposits Produced During Dissolution Reactions

In many of the runs conducted during this study, a thin solid residue was deposited on the wall of the reactor during the reaction. As mentioned previously, this residue was analyzed as primarily copper, with trace amounts of other metals such as aluminum and iron.
The solids appeared in the reactor once foam control was established. As the reaction progresses towards completion, the reaction mixture becomes more viscous and the material which splashes will coat the reactor walls for a short period of time before falling back into the bulk fluid. Because that part of the reactor wall is still jacketed, it is suspected that water and MEA are vaporizing, leaving copper behind. In an agitated vessel, this effect should not occur.
Several times, the residue on the walls was not cleaned prior to beginning the next run. When this was done, some of the material would generally dissolve into the MEA/water mixture during carbon dioxide addition, while the rest would dissolve while the mixture was heating.

Example 21

Effect of Increased Atmospheric Pressure on Dissolution Rates in an Aqueous Amine Solution

To examine the effect of increased atmospheric pressure on copper dissolution rates, an agitated, stainless-steel pressure reactor was employed, using copper powder (Acutech) as the copper source. Two runs were conducted—one at atmospheric pressure and one at 30 psig. The runs were conducted with a 500 ml charge at 70° C., using a 40% MEA/water solution with 0.125% active Q-5097, 100 ppm active WP-55 antifoam and 10.3% copper powder. The results are shown in FIG. 16 and indicate that increased atmospheric pressure increases copper dissolution rates. Foam was a significant issue during both runs as anti-foam was added several times during each run. Although foam levels could not be seen inside the reactor, they were visible once the foam reached the vent. Note that the inconsistencies near 7 hours, in the profiles of FIG. 16, are due to shutdown of the reactor overnight.

Example 22

Density Determinations of Reaction Solutions

The concentration of dissolved copper during a run was measured continuously, in-line. Samples of several reaction solutions were taken and measured for density and for copper content. Densities were measured at room temperature (22° C.) using a lb./gal. cup and copper concentrations were measured by X-Ray Fluorescence. The results are plotted in FIG. 18. There is a significant change in the density as the reaction progresses, approximately 1.02 g/ml at start-up and 1.17 g/ml at 10% copper.

Example 23

Effect of Adding Air and Carbon Dioxide Gas Simultaneously to The Reaction Column

An experiment was conducted in a modified reactor to measure the copper dissolution rate of scrap copper of a reaction using a 48% MEA solution (by weight), using a total amount of carbon dioxide in an amount less than 5% by weight, in a reaction where carbon dioxide and air are introduced simultaneously to initiate the reaction and continued until the weight ratio of MEA to copper was 3.36:1. The PVC reactor was modified by adding a new bottom section containing three inlets (1 liquid, 1 air, and 1 carbon dioxide gas inlet) to allow for the addition of both gases (with separate flow control). The vapor outlet at the top of the column was connected to its liquid return line. This allowed any overflow caused by foaming to return to the reaction.

The copper dissolution process was run at a temperature of 70° C. The surfactant used was Bardac LF, and the antifoam used was a 10% solution of Foamtrol WP-55. Fresh scrap copper (#1 chops) was loaded into the column in an amount 7.3 times the theoretical amount of copper necessary. Carbon dioxide was added at a flow rate of 5.5 SCFH. Air was added at a flow rate of 8.0 SCFH. The reaction achieved an 11.61% copper concentration in 3.50 hours. The results are shown in Table VIII. The copper dissolution rate achieved a maximum rate of 8.8% copper/hour, 1.08 hours into the reaction. The amount of carbon dioxide added to the reaction was about 4.7%.

TABLE VIII


Process Parameters and Rate of Copper Dissolution

				Dissolution
	Elapsed	Elapsed Air		Rate
Sample	CO₂Time	Time	% Copper	(% Copper/	% CO₂
No.	(hours)	(hours)	Dissolved	hour)	Analyzed

1	0.00	0.00	0.00	—	—
2	0.18	0.18	0.12	0.67	—
3	0.35	0.35	0.36	1.36	4.72
4	—	0.50	0.79	2.88	—
5	—	1.08	5.84	8.79	—
6	—	1.54	7.97	4.59	—
7	—	2.15	9.99	3.31	—
8	—	2.51	10.61	1.74	—
9	—	3.06	11.35	1.35	—
10	—	3.50	11.61	0.74	—

Claims

1. A method for dissolving copper or a copper-containing material comprising the steps of mixing copper or a copper-containing material, water, amine, carbon dioxide in an amount less than about 5% by weight, and an oxidant such that the aqueous solution contains between about 5 and about 12% dissolved copper within 5 hours.

2. The method of claim 1, wherein the aqueous solution contains between about 5 and 12% dissolved copper within 3 hours.

3. The method of claim 1, wherein the aqueous solution contains between about 5 and about 12% dissolved copper within 1 hour.

4. The method of claim 1, wherein the aqueous solution further comprises a surfactant.

5. The method of claim 4, wherein the surfactant is (C₁₂-C₁₈) dimethylbenzylammonium chloride.

6. A method for dissolving copper or a copper-containing material comprising the steps of mixing the copper or a copper-containing material, water, amine, carbon dioxide, and an oxidant such that the aqueous solution contains between about 5 and about 12% dissolved copper within 5 hours.

7. The method of claim 6, wherein the aqueous solution contains between about 5 and 12% dissolved copper within 3 hours.

8. The method of claim 6, wherein the aqueous solution contains between about 5 and 12% dissolved copper within 1 hour.

9. A method for dissolving copper or a copper-containing material comprising the steps of mixing the copper or a copper-containing material, water, an amine, and carbon dioxide, and introducing an oxidant to the solution at an air at flow rate of between about 0.5 and 100 standard cubic feet per hour (SCFH).

10. The method of claim 9, wherein the air flow rate is between about 0.5 and 5 SCFH.

11. The method of claim 9, wherein the aqueous solution contains between about 5 and 12% dissolved copper within 5 hours.

12. The method of claim 11, wherein the aqueous solution contains between about 5 and 12% dissolved copper within 3 hours.

13. The method of claim 12, wherein the aqueous solution contains between about 5 and 12% dissolved copper within 1 hour.

14. A method for dissolving copper or a copper-containing material comprising the steps of mixing the copper or a copper-containing material, water, amine, carbon dioxide, an oxidant and an and a quaternary ammonium change to surfactant then cationic surfactant compound in an amount sufficient to produce a rate at least twice that observed in the absence of the quaternary ammonium compound.

15. The method of claim 14, wherein the solution contains between about 5 and about 12% dissolved copper within 5 hours.

16. The method of claim 14, wherein the aqueous solution contains between about 5 and 12% dissolved copper within 3 hours.

17. The method of claim 14, wherein the aqueous solution contains between about 5 and 12% dissolved copper within 1 hour.

18. The method of claim 14, wherein the quaternary ammonium compound is present in an amount between 0.125 and 0.250% by weight.

19. The method of claim 1, wherein the copper or a copper-containing material, water, amine and the oxidant are mixed in a single reaction chamber.

20. The method of claim 19, wherein the single reaction chamber is columnar.

21. The method of claim 1, wherein the water, amine and the oxidant are mixed in one reaction chamber and the resulting solution is circulated through copper or a copper-containing material in a second reaction chamber.

22. A method for dissolving copper comprising the steps of mixing the copper, water, between about 40 and about 50% monoethanolamine, carbon dioxide in an amount less than about 5% by weight, an oxidant and a quaternary ammonium compound such that the aqueous solution contains between about 5 and about 12% dissolved copper within 5 hours.

23. The method of claim 22, wherein the water, amine and the oxidant are mixed in one reaction chamber and the resulting solution is circulated through copper or a copper-containing material in a second reaction chamber.

24. The method of claim 22, wherein the wherein the carbon dioxide is added to the solution after addition of the copper.

25. A method for producing a metal amine solution, comprising the steps of: mixing a water-insoluble metal or metal-containing material, water, an amine, an oxidizing agent and a surfactant in a concentration sufficient to produce a metal-amine solution at a rate at least 1.5-fold that observed in the absence of the surfactant.

26. The method of claim 25, wherein the surfactant is in a concentration sufficient to produce a metal-amine solution at a rate at least 2-fold that observed in the absence of the surfactant.

27. The method of claim 25, wherein the surfactant is in a concentration sufficient to produce a metal-amine solution at a rate at least 5-fold that observed in the absence of the surfactant.

28. The method of claim 25, wherein the surfactant is in a concentration sufficient to produce a metal-amine solution at a rate at least 10-fold that observed in the absence of the surfactant.

29. The method of claim 25, wherein the surfactant is in a concentration sufficient to produce a metal-amine solution at a rate at least 50% greater than that observed in the absence of the surfactant.

30. The method of claim 25, wherein the metal-containing material is a copper-containing material.

31. The method of claim 30, wherein the copper-containing material is cuprous oxide.

32. The method of claim 25, wherein the metal is a copper.

33. The method of claim 25, wherein the amine is selected from the group consisting of any compound that has the following chemical structure:

wherein R1, R2, R3, R4, R5, R6 is independently selected from the group consisting of H,-CH₃,—C₂H₅; —C₂H₄OH

34. The method of claim 33, wherein the amine is monoethanolamine, diethanolamine, ethylamine, diethylamine, dimethylethylamine, dimethylethanolamine, or mixtures thereof.

35. The method of claim 34, wherein the amine is monoethanolamine.

36. The method of claim 25, wherein the surfactant is non-ionic.

37. The method of claim 25, wherein the surfactant is anionic.

38. The method of claim 25, wherein the surfactant is cationic.

39. The method of claim 38, wherein the cationic surfactant is a quaternary ammonium compound.

40. The method of claim 39, wherein the quaternary ammonium compound has the following structure:

wherein R₁, R₂, R₃, and R4 are independently selected from alkyl or aryl groups and X⁻selected from chloride, bromide, iodide, carbonate, bicarbonate, borate, carboxylate, hydroxide, sulfate, acetate, laurate, or any other anionic group.

41. The method of claim 39, wherein the quaternary ammonium compound is n− alkydimethyl benzyl ammonium chloride, alkyldimethylbenzylammonium chloride, alkyldimethylbenzylammonium carbonate/bicarbonate, dimethyldidecylammonium chloride, didecyl dimethyl ammonium chloride, or dimethyldidecylammonium carbonate/bicarbonate.

42. The method of claim 39, wherein the quaternary ammonium compound is (C₁₂-C₁₈) dimethylbenzylammonium chloride.

43. The method of claim 25 further comprising a defoaming agent.

44. The method of claim 43, wherein the defoaming agent is a silicon polymer.

45. The method of claim 44, wherein the silicon polymer is polyoxylalkylene silicon.

46. The method of claim 25, wherein the surfactant is a low-foaming surfactant.

47. The method of claim 39, wherein the quaternary ammonium compound is low foaming.

48. The method of claim 25, wherein the oxidizing agent is oxygen, air, ozone, or hydrogen peroxide.

49. The method of claim 25, further comprising the step of heating the solution to between 30 and 100° C.

50. The method of claim 25, wherein temperature is maintained between about 50° and 100° C.

51. The method of claim 25, wherein temperature is maintained between about 50° and 70° C.

52. The method of claim 25, wherein the solution contains between about 20 and about 60% amine.

53. The method of claim 52, wherein the solution contains between about 30 and about 50% amine.

54. The method of claim 52, wherein the solution contains between about 40 and about 50% amine.

55. The method of claim 25, wherein the oxidant is introduced to the aqueous solution at a flow rate of between about 0.5 and 10 SCFH.

56. The method of claim 25, wherein the oxidant is introduced to the aqueous solution at a flow rate of between about 0.5 and 5 SCFH.

57. The method of claim 25, further comprising the step of adding an acid to the solution.

58. The method of claim 57, wherein the acid is carbon dioxide.

59. The method of claim 57, wherein the acid is added to the solution prior to addition of the metal or metal-containing material.

60. The method of claim 57, wherein the acid is added to the solution after addition of the metal or metal-containing material.

61. The method of claim 57, wherein the solution comprises less than about 5% acid by weight.

62. The method of claim 25, wherein the pH of the aqueous solution is initially between about 9.5 and 11.5.

63. The method of claim 62, wherein the pH of the aqueous solution is initially between about 10.5 and 11.5.

64. The method of claim, 25, wherein the pH of the aqueous solution is maintained between about 10 and 12 .

65. The method of claim 64, wherein the acid is carbon dioxide.

66. The method of claim 25, wherein the aqueous solution further comprises an anti-foaming agent.

67. The method of claim 25, further comprising the step of stirring the solution.

68. The method of claim 25, further comprising the step of circulating the solution.

69. The method of claim 25, wherein the solution contains between about 5 and about 12% dissolved copper within 5 hours.

70. The method of claim 25, wherein the aqueous solution contains between about 5 and 12% dissolved copper within 3 hours.

71. The method of claim 25, wherein the aqueous solution contains between about 5 and about 12% dissolved copper within 1 hour.

72. The method of claim 25, wherein the method is conducted at pressure greater than 1 atmosphere.