NL7905266A - METHOD FOR REMOVING METALS FROM BIMETALLIC SALT COMPLEXES CONTAINING WASTE MATERIALS. - Google Patents

Description

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70 8006

Tenneco Chemicals, lac.

Saddle Brook, New Jersey, United States of America.

Process for the removal of metals from bimetallic salt complexes containing the waste materials.

The invention relates to a method of removing metals from waste materials comprising bimetallic salt complexes of the general formula M-Maromat and / or the general formula M-Ox. aromatics, where MT is a group IB metal ix n ii 1 5 language, MT_ is a group IIII-A metal, X halogen, n is the sum of the valences of MT and, and aromatic is a monocyclic aromatic hydrocarbon or a halogenated aromatic hydrocarbon with 6-12 carbon atoms. More particularly, the invention relates to a process for recovering copper and aluminum from cuproaluminum tetrachloride compiexes containing waste materials.

Bimetallic salt amplexes with the general formula ^ X ^. aromatics are used to isolate such complexing ligands, such as olefins, acetylene, aromatics and carbon monoxide, from gas mixtures. For example, U.S. Pat. No. 3,651,159 discloses a process in which a liquid sorbent consisting of a solution of cuprous aluminum tetrahalide in toluene is used to isolate ethylene, propylene and other complexable ligands from a feed gas stream. The complexed ligands 20 are recovered by ligand exchange with toluene. The resulting solution of cuproaluminum tetrahalide toluene in toluene is recycled. and used to isolate additional amounts of the complexable ligands from the feedstream. US Pat. No. 3,647,3 ^ 3 discloses a process in which a hydrocarbon pyrolysis gas stream is contacted with a cuprc aluminum net chloride solution in toluene to isolate acetylene from the gas stream in the form of a solution of the complex MC = CH.Cu Aid ,, 790 52 66 * 2 - ».

in toluene. Acetylene is stripped from this complex with toluene while the cupro-aluminum tetrachloride-toluene complex is recycled.

In these processes, in which a liquid sorbent 5 containing a bimetallic salt complex is recycled without purification and used for long periods of time, a gradual increase in the amounts of reaction byproducts and other impurities takes place until such an amount of these impurities is present that the efficient operation of the process is disrupted. When e.g. the liquid sorbent is contacted, with a gas feed stream containing an alkene with 2-k carbon atoms, part of the olefin reacts with the aromatic hydrocarbon or the halogenated aromatic hydrocarbon in the sorbent to form alkylated aromatic compounds of which some are polymerized to olefin oligomers. Any water present in the gas stream reacts with the bimetallic salt complex to form the complex. aromatics, which have limited solubility in the liquid sorbent. When the liquid sorbent contains such amounts of these and other contaminants that deposits on the heat exchangers, blockage of pipes and other contamination of the installations occur, it must be purified, e.g. by precipitation precipitating a sludge comprising the sparingly soluble bimetallic salt complexes, which sludge is separated therefrom or the sorbent is replaced by a fresh liquid sorbent.

When a group IB metal halide is reacted with a group IIIA metal halide in the presence of an aromatic hydrocarbon solvent to form the liquid sorbent, usually also a small amount of sludge is formed which contains a major amount of the bimetallic salt complex, which is formed due to the presence of impurities such as M 2 OX and water in the reactants. This sludge, which is only slightly soluble in the liquid sorbent, is removed before the sorbent is used to isolate complexable ligands from 790 5 2 66 * 3 feed gas streams.

Due to their high metal content, the spent liquid sorbent, the sludge separated from the liquid sorbent and the sludge formed during the preparation of the liquid sorbent cannot be discharged into a sewer or drainage basin without causing serious pollution problems. In addition, it is economically desirable to recover the metals, usually copper and aluminum, from these effluent materials.

Several methods have been proposed for separating metals from sludge and spent liquid sorbents including the bimetallic salt complex. In the

U.S. Patent 3-8 ^ 5,188 discloses a process in which the Group IB metal is recovered in the spent liquid sorbent as its halide by contacting the liquid sorbent 15 with anhydrous ammonia and depositing the metal halide that precipitates from the sorbent. to separate. It has also been proposed to burn the waste materials, but since these materials contain about 30% metal salts, this method leaves a significant amount of metal ash to be disposed of without causing environmental problems. These methods are generally not economical and impractical for industrial scale implementation, and may also cause environmental pollution problems.

The invention relates to an improved process for removing metals from waste materials comprising a bimetallic salt complex complex comprising the complex. aromatics, the complex aromatics or a mixture of these complexes as well as an organic component containing an aromatic hydrocarbon, a calcined aromatic hydrocarbon, an alkylated aromatic hydrocarbon, olefin olefins, tar substances or mixtures thereof. These waste materials may consist of spent liquid sorbent used to remove collapsible ligands from feed gas streams, sludge isolated from freshly prepared liquid sorbent. or sludge isolated from spent liquid sorbent. This method which is more efficient and economical to use than the method described in U.S. Patent 790 52 66 i '.

* 3.81 (-5.188 and which avoids the pollution problems associated with the previously proposed methods, provides an environmentally safe procedure for the disposal of bimetallic salt complex-containing waste materials, as well as an effective procedure for the removal of metals from these waste materials .

In the process of the invention, the bimetallic salt complex-containing waste materials from which the metals are to be recovered are hydrolyzed under either acidic or alkaline conditions. The hydrolyzed material is split into an upper organic phase and a lower water phase.

After the isolation of the phases, the organic phase can be distilled to separate the aromatic hydrocarbons therefrom, or it can be burned without causing environmental problems. The group I-B and the group III-A metals are recovered from the water phase 15.

The spent liquid sorbents from which the metals can be recovered by the process of the invention consist of solutions of bimetallic salt complexes in an aromatic hydrocarbon or a halogenated aromatic hydrocarbon containing alkylated aromatic hydrocarbons, alkylated halogenated aromatic hydrocarbons, olefin oligomers, other bimetallic salt complexes and / or may contain tar materials. The bimetallic salt complexes in the liquid sorbents generally have the formula MTMT-fXn. aramate and / or the general formula. Mj.-j. 0X. ar regalia.

fine. is a group I-B metal; i.e. copper, silver or gold. Copper (l) is the preferred metal. a group III-A is metal; i.e., boron, aluminum, gallium, indium or thallium. Boron and aluminum are the preferred materials, aluminum being particularly preferred. X is halogen, i.e., fluorine, chlorine, bromine or iodine; it is preferably chlorine or bromine. The sum of the valences Mj. and Μ, -j. is represented by n. "Aromatic means a monocyclic aromatic hydrocarbon or halogenated aromatic hydrocarbon with 6-12 carbon atoms 790 52 66 *".

5, preferably 6-9 carbon atoms, such as benzene, toluene, ethylbenzene, xylene, nesitylene, chlorobenzene, bromobenzene, iodobenzene, dichlorobenzene, dibrobenzene, chlorotoluene, chlorotoluene, or chlorobylene or to-5 lueen. Examples of these bimetallic salt complexes are the following: CuBF ^ benzene, CuBCl ^ benzene, AgEF ^ mesitylene, AgBCl ^ xylene, AgAICl ^ xylene, AgAlBr ^. Bromobenzene, CuGaCl ^ toluene, Culnl ^. 1,2 -Cl-chlorobenzene, CuTl-1-p-chlorotoluene and the like. The bimetallic salt complex in the waste material is usually CuAlCl 2 benzene, CuAlCl 2 toluene, or CuAlBr 2 benzene. The aromatic hydrocarbon or the calogenated hydrocarbon into which the bimetallic salt complex is discharged is usually (and preferably) the same hydrocarbon used for the preparation of the bimetallic salt complex, although it is not excluded to use another hydrocarbon. The total amount of aromatic hydrocarbon or halogenated aromatic hydrocarbon in the liquid sorbent, i.e. z. the amount in the bimetallic salt complex plus the amount used as the solvent is at least 10 mol # of the amount of the bimetallic salt present. It is preferred that the amount of aromatic hydrocarbon or halogenated aromatic hydrocarbon be 100-150 mol # of the amount of the bimetallic salt. The particularly preferred liquid sorbents have 25 - T5 wt.% CuAlCl 2 benzene in benzene or CuAlCl 2 toluene in toluene.

The waste materials from which the metals can be removed by this method generally comprise a major amount of the bimetallic saline complex, which is usually CuAlCl 2 AlOCl-toluene, and minor amounts of an aromatic hydrocarbon, such as benzene or toluene.

They may also contain other bimetallic salt complexes, such as M JC ,. aromatics, which are usually CuALCl 2 toluene or CuAlCl 2 benzene, organic reaction by-products and tar substances. They preferably consist of (1) a liquid sorbent which is a solution of cuprous aluminum tetrachloride in benzene or toluene, used in a process for the removal of carbon monoxide, ethylene or other complex 7905266 *,

a

eerbarexible ligands from a feed gas stream, until it contains such an amount of impurities as alkylated aromatics, olefin oligomers, tar substances, CuCl 2 AlOCl and other sorbent-insoluble bimetallic salt complexes, thereby rendering effective operation of the ligand tolerance method impossible and the liquid sorbent in the system must be replaced, (2) a sludge comprising bimetallic salt amplitudes formed by the reaction of cuproaluminum tetrachloride with small amounts of water, hydrogen sulfide, amines or alcohols present as impurities in the feed gas stream 10, and isolated from the cold liquid sorbent, or (3) a sludge formed during the preparation of the liquid sorbent and comprising a major amount of CuAlCl 2 .A 10 Cl and minor amounts of Cu 2 Cl 2 and either benzene or toluene.

If the waste material contains a high concentration of tar, alkylated aromatic hydrocarbons and / or olefin oligomers, it can be diluted with half to double volume of an aromatic hydrocarbon to improve its handling and pumpability before applying the process of the invention is being treated. It is preferably diluted with an equal volume of toluene.

In one embodiment of the invention, the waste material is contacted with water and sufficient alkali metal hydroxide, usually sodium hydroxide, to form a hydrolysis mixture. has a pH in the range of 5 - 7> preferably either 6 - 7 or higher than 11, and in which almost all of the copper present is converted to copper oxide and all of the aluminum into aluminum hydroxide. On complete hydrolysis, the hydrolysis mixture splits into an upper organic phase containing a predominant amount of toluene or benzene and a. lower aqueous phase, which is a suspension of copper oxide and aluminum hydroxide. After separation of the organic phase, the suspension can be discharged into a waste disposal basin or well without any problem. If it is desired to convert the copper to a compound which is less soluble than copper oxide, the slurry may be treated with sodium hydrosulfide prior to disposal. Optionally, the separated slurry or metal compounds 790 52 66 τ * 'can be fed to a metal-reprocessing facility and thus retained. The separated organic phase can be burned or distilled to separate toluene and benzene.

In a preferred embodiment of the invention, the waste material from which the metals are to be removed is contacted with water and sufficient sodium hydroxide to form a hydrolysis mixture with a µl of at least 11.

After removal of the organic layer from the hydrolysis mixture, precipitated copper hydroxide is removed from the water phase by filtration. The recovered copper hydroxide can be used as a land filler or converted to copper metal. The filtrate contains soluble sodium aluminate which can be converted to aluminum hydroxide, which can be used as a flocculating agent in a settling basin.

In another embodiment of the invention, the waste material is contacted with water containing sufficient hydrogen chloride to convert virtually all the copper and aluminum in the bi-metallic salt complexes into their water-soluble chlorides. In most cases, 5-50 parts by volume of 2-20% 2C aqueous chlorine water or acid are used per volume part of the waste material. Particularly good results have been obtained when using k - 10 parts by volume of 5 - 15% aqueous chlorine, which is acidic material per volume part of the waste material. To achieve complete conversion of the metals to their chlorides, the pH of the hydrolysis mixture should be in the range of 1.3 - 2.3 and preferably 2.0. On complete hydrolysis, the hydrolysis mixture splits into an upper organic phase, which contains a predominant amount of benzene or toluene, and a lower water phase, which contains copper and aluminum cororides. The organic phase which is separated from the water phase by e.g. can be distilled to recover toluene or benzene, or burned. A reducing agent, such as a metal such as aluminum, iron or magnesium, is added to the acidic aqueous phase in an amount that is stoichiometrically equivalent to the amount of copper in the solution, whereby practically all the copper will be precipitated from the solution. The reduction 790 5 2 66 8 - i '.

'A

Preferred agent is aluminum because of its low equivalent weight. Only 9 kg of aluminum is required to produce 63.5 kg of copper, while 18 kg of iron or 12 kg of magnesium are required to achieve the same result. Furthermore, aluminum is inexpensive, while when using it no other metals from the metal recovery method are introduced into the reaction products.

The precipitated copper recovered from the aqueous solution by decanting or filtering is very pure and can be sent to a copper reprocessor. The filtrate containing aluminum chloride and hydrochloric acid can be discarded without contamination problems. However, it is often preferred that the aluminum be recovered by adding a sufficient amount of alkali metal hydroxide thereto to bring the pH to 5-7, thereby precipitating the aluminum hydroxide. Preferably, a 10-20% aqueous solution of sodium hydroxide is used to bring the filtrate to a pH of 5-5.5. When the free-flowing suspension formed in this way settles, a clear liquid top layer, which is an aqueous solution of an alkali chloride, usually sodium chloride, can be separated from the precipitated aluminum hydroxide and discarded. The aluminum hydroxide recovered can e.g. as a flocculant in water treatments.

The invention will now be further illustrated with the following examples. In these examples, all parts are in volume unless otherwise indicated.

Example. I

A. A liquid sorbent containing 28.6 mole% cupronium aluminum tetrachloride and 71.1 mole # toluene was prepared by adding 1.2 moles cuprous chloride to 1 mole anhydrous aluminum chloride in toluene. The resulting solution was filtered to remove unreacted cuprous chloride and insoluble impurities.

B. A gas mixture obtained by pyrolysis of natural gas had the following composition: hydrogen 5 & 0 mm 35 carbon monoxide 280 mm acetylene 75 mm 790 5 2 66 9> * *.

methane 60 ma carbon dioxide 25 ma

The pyrolysis gas evaporated at ambient temperature and a pressure of about 1.3 bar (absolute) fed to an absorption column 5 in which it was contacted with an amount of liquid sorbent of Example 1A containing at least enough cuproaluminum tetrachloride to react with all of the acetylene and carbon monoxide present in the feed gas. The acetylene and carbon monoxide and the gas mixture reacted with the liquid sorbent as it passed through the column to form a solution containing the acetylene-cupro-aluminum tetrachloride complex and the carbon monoxide-cuprc-aluminum tetrachloride complex. This solution was fed to a stripping column in which it was contacted with benzene vapor at 80 ° C. The mixture of benzene vapor and carbon monoxide exiting the cc was cooled to 25 ° C to separate the carbon monoxide from the benzene. The sorhent solution which then contained cuprous aluminum tetrachloride and the acetylene-cuprous aluminum tetrachloride crosplex was fed to a stripping column in which it was contacted with benzene vapor at 35 ° C. The vapor leaving column 20 was cooled to condense the benzene and separate it from the acetylene. The stripped sorbent was returned to the absorption column in which it was reacted with additional amounts of carbon monoxide and acetylene in the gas stream.

0. Having used the liquid sorbent for several months in the process described in Example 13, it was found to contain impurities which impeded the removal of carbon monoxide and acetylene from the feed gas stream. Replace the sorbent with fresh liquid sorbent.

D. The spent liquid sorbent, which had a species-3G equivalent weight of 1.22, was added in portions to 2.0 g of a 15% rs aqueous sodium hydroxide solution. During the addition, the hydrolysis mixture was stirred effectively and its pH measured and monitored. After adding 100 ml of consumed liquid sorbent over a period of 5 hours, the hydrolysis mixture, the pH of which was pH 6 and the temperature had risen to 30 ° C, formed an upper 790 5 2 66 V *. - '* ----- * -' "10 phase consisting largely of toluene and a lower water phase containing about 75 ml of precipitated copper oxide. After adding 110 ml of consumed liquid sorbent, the water phase was, which had a pH of 6.8 had a suspension with a paint-like consistency After separation of the organic phase, the suspension was discharged into the waste disposal basin.

The organic phase was distilled and the recovered toluene returned to step I A._

Example II

To 127 kg of a sludge comprising CuAlCl 2 .AlOCl, CuAlCl 2 .to luene, toluene, alkylated toluene and tar substances, Λ 2k kg of a 50% aqueous sodium hydroxide solution was added, followed by 214 kg of water while stirring. the hydrolysis mixture. The hydrolysis mixture which had a pH of 6 split into an upper organic phase and a lower water phase, which consisted of a suspension of paint-like consistency containing copper oxides and aluminum hydroxide. The organic phase was separated and distilled to recover toluene. To the suspension, k2 kg of a 20% 1 s aqueous sodium hydrosulfide solution was added to convert the copper oxides into copper sulfide. The resulting black suspension was pumped to a waste disposal basin.

Example III

A. A liquid sorbent prepared according to the method described in Example 1A was used in the method described in Example 1B to remove carbon monoxide from a gas stream. After several months of operation in the process, the liquid sorbent containing impurities interfering with the removal of carbon monoxide and acetylene from the feed gas stream was replaced with fresh liquid sorbent.

B. Twenty-five parts of the spent liquid sorbent, which had a specific gravity of 1.22, were added to a mixture of 15 parts of concentrated hydrochloric acid and 150 parts of water at room temperature. The reaction mixture, which had a pH of 2, split into an upper phase containing 25 parts of toluene and a lower clear acidic aqueous phase. The phases were separated 79052 66 i *.

11 the pine and the toluene phase are used to prepare fresh liquid sorbent. 2 wt. parts of aluminum powder were added to the acidic evaporation phase. The copper that precipitated was collected and dried at 110 ° C. 5 parts of copper are obtained. The filtrate containing Uppm copper was diluted with vessel to 200 parts and then neutralized to a pH of 5 by adding 20 parts of a 15% sodium hydroxide solution to form a free-flowing suspension. After settling the suspension for one hour, the clear liquid top layer, which consisted of an aqueous sodium chloride ride solution, was separated from the precipitated aluminum hydroxide.

Example I7

Twenty-five parts of a sludge containing CuAlCl ^. A10C1,

CuAlCl 4 toluene, toluene, alkylated toluene and tar substances were diluted with 25 parts of toluene. The resulting solution was slowly added to a mixture of 10 parts of concentrated hydrochloric acid and 100 parts of water. The reaction mixture immediately split into two phases. The upper phase, which are organic compounds. contained, separated and burned. 1 acid. part aluminum powder in two portions. 30 minutes after the addition of the aluminum, the precipitated copper is separated from the aqueous solution. The filtrate contained kppm copper.

Hr added sufficient 20% sodium hydroxide aqueous solution to the filtrate to adjust its pH to 5.5. The precipitated aluminum hydroxide was allowed to settle, after which it was collected. The clear liquid oven layer was removed.

Similarly, this method can be used to recover metals from the other bimetallic salt complex-containing waste materials described herein.

79052 66

Claims (8)

A method of recovering metal nit waste materials comprising a bimetallic salt complex component selected from complexes of the formula aromatics, complexes of the formula M ^ Ji ^ X ^ M ^ OX. Aromatic and mixtures thereof, wherein a group XB metal, a group III-A metal, X halogen, n the sum of the valences of and k ^. and aromatics represent a monocyclic aromatic hydrocarbon or a halogenated aromatic hydrocarbon with 6-12 carbon atoms, and an organic component selected from monocyclic aromatic hydrocarbons with 6-12 carbon atoms, halogenated aromatic hydrocarbons with 6-12 carbon atoms, alkylated aromatic hydrocarbons, olefin oligomers, tar substances and mixtures thereof, characterized in that a) the waste material is hydrolyzed under either acidic or alkaline conditions; O) the hydrolysis mixture is separated into an upper organic phase and a lower water phase; c) separating the organic phase from the water phase; and d) the metals are recovered from the water phase. 2. Process for the recovery of copper and aluminum from scrap mat eral ales comprising a b-metallic salt complex component selected from CuAlGI-1-aromatic "CuAlCl 2 -ALQX" aromatic and mixtures thereof, wherein the aromatic is a monocyclic aromatic hydrocarbon or a halogenated aromatic hydrocarbon of 6-12 carbon atoms, as well as an organic component selected from monocyclic aromatic hydrocarbons of 6-12 carbon atoms, monocyclic halogenated aromatic hydrocarbons of 6-12 carbon atoms, alkylated aromatic hydrocarbons, olefin oligamers, tar 3Q and mixtures thereof, with characterized in that a) the waste material is contacted with water and either hydrochloric acid or sodium hydroxide to form a hydrolysis agent; b) the hydrolysis mixture is separated into an upper organic phase and a lower water phase; c) the organic phase is separated from the aqueous solution, and d) copper and aluminum are recovered from the water phase. 3. Process according to claim 2, characterized in that a) the waste material is contacted with water and sufficient sodium hydroxide to form a hydrolysis mixture with a pE greater than 5; b) the hydrolysis mixture is separated into an upper organic phase and a lower water phase, which consists of a suspension of compounds selected from copper and aluminum oxides and hydroxides; and c) the organic phase of. the water phase is separated. k. Process according to claim 3, characterized in that the hydrolysis mixture formed in step a) 'has a pH of. 5 - T has. The process according to claim 3, characterized in that the hydrolysis mixture formed in step a] has a pH of at least 11. 6. Process according to claim 3, characterized in that the aqueous phase separated in step c} is contacted with sodium hydrosulfide to convert the copper oxide in the suspension to copper sulfide. A method according to claim 2, characterized in that a) the waste material is contacted with a sufficient amount of hydrofluoric hydrochloric acid to form a hydrolysis mixture with a pE of 1.8 - 2.3; b} the hydrolysis mixture is separated into an upper organic phase and a lower aqueous phase, consisting of an aqueous solution of cupric chloride and aluminum trichloride; c) separating the organic phase from the aqueous solution; 790 5 2 66 i. s * lij. d) an amount of aluminum is added to the aqueous solution which is stoichiometrically equivalent to the amount of cuprous chloride in the solution whereby copper is precipitated; E) the precipitated copper is removed from the aqueous aluminum trichloride solution; f) sufficient 10-20% aqueous sodium hydroxide solution is added to the aqueous aluminum trichloride solution to bring the pH into the range of 5-7 thereby precipitating aluminum hydroxide from the aqueous sodium chloride solution and g) alum inium hydroxide is separated from the aqueous sodium chloride solution. 8. Method according to claim 7, characterized in that in step a) the waste material is brought into contact with 2 - 50 vol. parts of 2 - 20% aqueous chlorine, there is dust acid per volume. part of the waste material. 9. Process according to claim 2, characterized in that the waste material is diluted with half to double volume 20 of an aromatic hydrocarbon before it is hydrolyzed. 10. Process according to claim 2, characterized in that the hemetallic salt complex component of the waste material is selected from CuAlCl 2 toluene, CuAlCl 2 benzene, CuAlCl 2 AlOCl toluene, CuAlCl 2 AlQCl 2 benzene and mixtures thereof. 25 790 5 2 66