Method for leaching gold from waste heterogeneous gold-based catalyst and co-producing carbonyl compound

Abstract

The invention discloses a method for leaching gold and co-producing carbonyl compounds from a waste heterogeneous gold-based catalyst, which specifically comprises the following steps: adding the waste gold-based catalyst into a reaction kettle, adding amine or alcohol compounds, copper salt and iodized salt, reacting for 2-24 hours at the room temperature of 100 DEG C in a carbon monoxide / air atmosphere, filtering, washing, and drying to obtain the carbonyl compounds. The leaching of gold in the waste multiphase gold-based catalyst is realized, and corresponding useful carbonyl compounds such as urea, carbamate and carbonic ester are generated. According to the method for leaching the gold and co-producing the carbonyl compound from the waste heterogeneous gold-based catalyst, provided by the invention, highly toxic cyanide, strong acid or strong oxidant is not used. By means of the method, the gold leaching rate of 98% or above can be achieved at most, useful carbonyl compounds can be generated through the carbonylation reaction of used amine and alcohol, and two purposes are achieved at a time.

Description

Technical Field

[0001] The invention relates to a method for leaching gold from a waste multiphase gold-based catalyst and co-producing a carbonyl compound, belonging to the technical fields of metallurgical chemistry and organic synthetic chemistry. Background Art

[0002] Gold is a precious metal resource. Due to its unique properties, it was used not only as currency but also as jewelry in the early days. With the development of scientific metals, it is increasingly used in modern electronics, medicine and chemical catalysis. As a non-renewable resource, the demand for gold is increasing. The demand and consumption are growing year by year, and the growth trend is becoming more and more obvious. Therefore, it is of great significance to recover gold from secondary resources.

[0003] Currently, more than 90% of gold recovery in the mining industry and secondary resource recovery is based on the cyanidation method, which relies on the use of chemical reagents and highly toxic cyanide salts as leaching agents (see references: Dong Shu. Analysis of Chinese Patents on Gold Extraction Technology [J]. Science and Technology Wind, 2018, (29): 86; Wu Weihuang. Research Status and Progress of Gold Ore Treatment Methods [J]. Gold, 2023, 44 (01): 42-48.). However, the use of cyanide poses huge challenges in terms of environment, health and safety. Therefore, alternative new recovery methods are crucial to replace the cyanidation process to comply with new regulations and safety issues. In recent years, non-cyanide gold leaching technologies such as thiourea method, thiosulfate method and halogenation method (including chlorination method, bromination method and iodination method) have received widespread attention (see reference: Lu Shunli. Research Status of Non-cyanidation Gold Extraction Technology [J]. Yunnan Metallurgy, 2011,40 (03): 32-36+41). Gold in spent heterogeneous gold-based catalysts can be considered an attractive gold source, and it is estimated that the gold content in spent heterogeneous gold-based catalysts (usually >0.1 wt.%) is hundreds to thousands times that of natural gold ore or waste electronic equipment.

[0004] Carbonyl compounds refer to a class of organic compounds containing carbonyl groups. Depending on the environment, carbonyl compounds can refer to: aldehydes, ketones, carboxylic acids and carboxylic acid derivatives (including anhydrides, acyl halides, amides, esters, etc.). Carbonyl compounds can be prepared by catalytic carbonylation reactions. For example, products such as urea and carbamates can be obtained by carbonylation of amines or alcohols. Urea and carbamates can be used as many useful drugs or pesticides, and can also be used as precursors for the preparation of isocyanates by non-phosgene methods. Carbonates are widely used in many fields such as the synthesis of polycarbonates, solvents, and fine chemicals.

[0005] However, there is no report on a method for efficiently leaching gold from waste heterogeneous gold-based catalysts and co-producing carbonyl compounds. Therefore, the present invention provides a method for leaching gold from waste heterogeneous gold-based catalysts and co-producing carbonyl compounds. Summary of the invention

[0006] The present invention aims to provide a method for leaching gold from waste heterogeneous gold-based catalysts and co-producing carbonyl compounds, which can achieve a higher gold leaching rate and also produce useful carbonyl compounds during the leaching process.

[0007] To achieve the above object, the present invention adopts the following technical solutions: A method for leaching gold from waste heterogeneous gold-based catalysts and co-producing carbonyl compounds is provided, which comprises adding the waste heterogeneous gold-based catalysts together with copper salts, iodine salts and at least one of amine or alcohol compounds into a reaction kettle, and reacting them at room temperature to 100° C. for 2 to 24 hours in a carbon monoxide / air atmosphere, thereby achieving leaching recovery of gold and generation of carbonyl compounds.

[0008] The waste multiphase gold-based catalyst is a multiphase gold-based catalyst that uses metal oxide as a carrier to load elemental gold; specifically, it is one of the used Au / ZnO catalyst, Au / Ga2O3 catalyst, Au / Al2O3 catalyst, Au / TiO2 catalyst, Au / CeO2 catalyst or Au / SiO2 catalyst.

[0009] The copper salt is at least one of cupric chloride, cuprous chloride, cupric bromide, cuprous bromide, cuprous iodide, cupric nitrate, copper sulfate or copper acetate, and the usage amount is 1% to 20% of the molar content of gold.

[0010] The iodized salt is at least one of sodium iodide, potassium iodide, lithium iodide, and quaternary ammonium iodide, and the usage amount is 5% to 20% of the gold molar content.

[0011] The structural formula of the amine compound is: , wherein R1 and R2 are respectively one of hydrogen, substituted or unsubstituted alkyl, aromatic or non-aromatic cyclic compounds containing or not containing heteroatoms, and the usage amount is 50 to 2000 times the molar content of gold.

[0012] The alcohol compound is one of methanol, ethanol, isopropanol, tert-butanol, butanol, isobutanol or sec-butanol, and the usage amount is 50 to 2000 times the gold molar content.

[0013] The volume ratio of the carbon monoxide / air atmosphere is 4:1 to 10:1, and the pressure is 0.5 MPa to 4 MPa.

[0014] The reaction mechanism of the present invention is as follows: first, the divalent copper iodide complex coordinates with amine and CO to produce a copper amide intermediate, and the amine or alcohol attacks the copper amide intermediate, and further nucleophilic elimination occurs to produce urea or carbamate and hydroiodic acid (HI). Hydroiodic acid generates iodine (I2) in an oxidizing atmosphere, and iodine and iodide ions coordinate to generate [I3] with strong oxidizing properties. - Ion, [I3] - It is possible to convert the gold on the gold catalyst into [AuI2] - After that, [AuI2] - , copper salts, and iodide ions form a synergistic catalytic system, which efficiently catalyzes the oxidative carbonylation of amines to form urea or carbamate and generate more HI, thereby achieving efficient gold leaching.

[0015] Compared with the prior art, the method provided by the present invention for leaching gold from waste heterogeneous gold-based catalysts and co-producing carbonyl compounds does not use highly toxic cyanide, strong acid or strong oxidant; the copper salt and iodine salt used can be recycled in the subsequent separation process; amines or alcohols with wide sources and low prices can generate useful chemicals such as urea, carbamate and carbonate (dimethyl carbonate) with added value. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is the main component of gold in the leaching solution obtained in Example 1 of the present invention.

[0017] Figure 2 This is a comparison chart of gold-based catalysts loaded with different metal oxides before and after leaching in the examples of the present invention. DETAILED DESCRIPTION

[0018] The present invention is further explained below with reference to specific embodiments.

[0019] Example 1 100 mg of used Au / ZnO catalyst (gold content of 0.79% wt.), cuprous iodide (4 mg), potassium iodide (16 mg), morpholine (1 mmol) and toluene (5 mL) were loaded into a 10 mL glass tube. The glass tube was placed in a batch reactor at room temperature and filled with 0.4 MPa air and 1.6 MPa CO in sequence (note: the lower and upper explosion limits of CO at RT and atmospheric pressure are 12.5% ​​and 74.2%, respectively, which is outside the explosion limit). Then, the reactor was stirred at 60 °C for 10 h. After that, the pressure was carefully released. The concentration of gold in the liquid phase was determined by inductively coupled plasma emission spectrometry (ICP, Agilent 720ES). The conversion of amine was analyzed by gas chromatography (Agilent 6820). The results showed that the concentration of Au in the leachate reached 41 mg / mL, the gold leaching rate was 51.2%, the conversion of morpholine reached 98%, and the selectivity of dimorpholine ketone (urea) was greater than 99%. High-resolution mass spectrometry analysis showed that the gold in the leaching solution was mainly in the form of [AuI2] - exists in the form of Figure 1 ).

[0020] The reaction formula is as follows: .

[0021] Example 2 100 mg of used Au / Ga2O3 catalyst (0.79% wt.), cuprous iodide (4 mg), potassium iodide (16 mg), morpholine (1 mmol), and toluene (5 mL) were loaded into a 10 mL glass tube. The glass tube was placed in a batch reactor at room temperature and filled with 0.4 MPa air and 1.6 MPa CO in sequence (Note: the lower and upper explosion limits of CO at RT and atmospheric pressure are 12.5% ​​and 74.2%, respectively, which is outside the explosion limit). Then, the reactor was stirred at 60 °C for 10 h. After that, the pressure was carefully released. The concentration of gold in the liquid phase was determined by inductively coupled plasma emission spectrometry (ICP, Agilent 720ES). The conversion of amines was analyzed by gas chromatography (Agilent6820). The results showed that the Au leaching rate reached 92%, the conversion of morpholine reached 98%, and the selectivity of dimorpholine ketone (urea) was greater than 99% ( Figure 2 ).

[0022] Example 3 100 mg of used Au / Al2O3 catalyst (0.79% wt.), cuprous iodide (4 mg), potassium iodide (16 mg), morpholine (1 mmol), and toluene (5 mL) were loaded into a 10 mL glass tube. The glass tube was placed in a batch reactor at room temperature and filled with 0.4 MPa of air and 1.6 MPa of CO in sequence (Note: the lower and upper explosion limits of CO at RT and atmospheric pressure are 12.5% ​​and 74.2%, respectively, which is outside the explosion limit). Then, the reactor was stirred at 60 °C for 10 h. After that, the pressure was carefully released. The concentration of gold in the liquid phase was determined by inductively coupled plasma emission spectrometry (ICP, Agilent 720ES). The conversion of amines was analyzed by gas chromatography (Agilent6820). The results showed that the Au leaching rate reached 92%, the conversion of morpholine reached 97%, and the selectivity of dimorpholine ketone (urea) was greater than 99% ( Figure 2 ).

[0023] Example 4 100 mg of used Au / TiO2 catalyst (0.79% wt.), cuprous iodide (4 mg), potassium iodide (16 mg), morpholine (1 mmol) and toluene (5 mL) were loaded into a 10 mL glass tube. The glass tube was placed in a batch reactor at room temperature and filled with 0.4 MPa air and 1.6 MPa CO in sequence (Note: the lower and upper explosion limits of CO at RT and atmospheric pressure are 12.5% ​​and 74.2%, respectively, which are outside the explosion limit). Then, the reactor was stirred at 60 °C for 10 h. After that, the pressure was carefully released. The concentration of gold in the liquid phase was determined by inductively coupled plasma emission spectrometry (ICP, Agilent 720ES). The conversion of amines was analyzed by gas chromatography (Agilent6820). The results showed that in two leaching experiments, the overall leaching rate of Au reached 89%, the conversion rate of morpholine reached 97%, and the selectivity of dimorpholine ketone (urea) was greater than 99% ( Figure 2 ).

[0024] Example 5 100 mg of used Au / CeO2 catalyst (0.79% wt.), cuprous iodide (4 mg), potassium iodide (16 mg), morpholine (1 mmol) and toluene (5 mL) were loaded into a 10 mL glass tube. The glass tube was placed in a batch reactor at room temperature and filled with 0.4 MPa air and 1.6 MPa CO in sequence (Note: the lower and upper explosion limits of CO at RT and atmospheric pressure are 12.5% ​​and 74.2%, respectively, which is outside the explosion limit). Then, the reactor was stirred at 60 °C for 10 h. After that, the pressure was carefully released. The concentration of gold in the liquid phase was determined by inductively coupled plasma emission spectrometry (ICP, Agilent 720ES). The conversion of amine was analyzed by gas chromatography (Agilent6820). The results showed that in two leaching experiments, the overall leaching rate of Au reached 82%, the conversion rate of morpholine reached 97%, and the selectivity of dimorpholine ketone (urea) was greater than 99% ( Figure 2 ).

[0025] Example 6 100 mg of used Au / SiO2 catalyst (0.79% wt.), cuprous iodide (4 mg), potassium iodide (16 mg), morpholine (1 mmol), and toluene (5 mL) were loaded into a 10 mL glass tube. The glass tube was placed in a batch reactor at room temperature and filled with 0.4 MPa of air and 1.6 MPa of CO in sequence (Note: the lower and upper explosion limits of CO at RT and atmospheric pressure are 12.5% ​​and 74.2%, respectively, which is outside the explosion limit). Then, the reactor was stirred at 60 °C for 10 h. After that, the pressure was carefully released. The concentration of gold in the liquid phase was determined by inductively coupled plasma emission spectrometry (ICP, Agilent 720ES). The conversion of amines was analyzed by gas chromatography (Agilent6820). The results showed that the Au leaching rate reached 98%, the conversion of morpholine reached 99%, and the selectivity of dimorpholine ketone (urea) was greater than 99% ( Figure 2 ).

[0026] Example 7 100 mg of used Au / SiO2 catalyst (0.79% wt.), copper chloride (2.8 mg), potassium iodide (16 mg), morpholine (1 mmol) and toluene (5 mL) were loaded into a 10 mL glass tube. The glass tube was placed in a batch reactor at room temperature and filled with 0.4 MPa air and 1.6 MPa CO in sequence (Note: the lower and upper explosion limits of CO at RT and atmospheric pressure are 12.5% ​​and 74.2%, respectively, which is outside the explosion limit). Then, the reactor was stirred at 60 °C for 10 h. After that, the pressure was carefully released. The concentration of gold in the liquid phase was determined by inductively coupled plasma emission spectrometry (ICP, Agilent 720ES). The conversion of amine was analyzed by gas chromatography (Agilent6820). The results showed that the Au leaching rate reached 97%, the conversion of morpholine reached 99%, and the selectivity of dimorpholine ketone (urea) was greater than 99%.

[0027] Example 8 100 mg of used Au / SiO2 catalyst (0.79% wt.), copper bromide (4.5 mg), potassium iodide (16 mg), morpholine (1 mmol) and toluene (5 mL) were loaded into a 10 mL glass tube. The glass tube was placed in a batch reactor at room temperature and filled with 0.4 MPa air and 1.6 MPa CO in sequence (Note: the lower and upper explosion limits of CO at RT and atmospheric pressure are 12.5% ​​and 74.2%, respectively, which is outside the explosion limit). Then, the reactor was stirred at 60 °C for 10 h. After that, the pressure was carefully released. The concentration of gold in the liquid phase was determined by inductively coupled plasma emission spectrometry (ICP, Agilent 720ES). The conversion of amine was analyzed by gas chromatography (Agilent6820). The results showed that the Au leaching rate reached 98%, the conversion of morpholine reached 99%, and the selectivity of dimorpholine ketone (urea) was greater than 99%.

[0028] Example 9 100 mg of used Au / SiO2 catalyst (0.79% wt.), copper bromide (4.5 mg), sodium iodide (16 mg), morpholine (1 mmol) and toluene (5 mL) were loaded into a 10 mL glass tube. The glass tube was placed in a batch reactor at room temperature and filled with 0.4 MPa air and 1.6 MPa CO in sequence (Note: the lower and upper explosion limits of CO at RT and atmospheric pressure are 12.5% ​​and 74.2%, respectively, which is outside the explosion limit). Then, the reactor was stirred at 60 °C for 10 h. After that, the pressure was carefully released. The concentration of gold in the liquid phase was determined by inductively coupled plasma emission spectrometry (ICP, Agilent 720ES). The conversion of amine was analyzed by gas chromatography (Agilent6820). The results showed that the Au leaching rate reached 98%, the conversion of morpholine reached 99%, and the selectivity of dimorpholine ketone (urea) was greater than 99%.

[0029] Example 10 100 mg of used Au / ZnO catalyst (0.79% wt.), cuprous iodide (4 mg), potassium iodide (16 mg), morpholine (1 mmol) and methanol (5 mL) were loaded into a 10 mL glass tube. The glass tube was placed in a batch reactor at room temperature and filled with 0.4 MPa air and 1.6 MPa CO in sequence (Note: the lower and upper explosion limits of CO at RT and atmospheric pressure are 12.5% ​​and 74.2%, respectively, which is outside the explosion limit). Then, the reactor was stirred at 60 °C for 10 h. After that, the pressure was carefully released. The concentration of gold in the liquid phase was determined by inductively coupled plasma emission spectrometry (ICP, Agilent 720ES). The conversion of amine was analyzed by gas chromatography (Agilent6820). The results showed that the concentration of Au in the leachate reached 57 mg / mL, the gold leaching rate was 72%, the conversion of morpholine reached 97%, and the selectivity of carbamate was greater than 99%.

[0030] The reaction formula is as follows: .

[0031] Embodiment 11 100 mg of used Au / ZnO catalyst (0.79% wt.), cuprous iodide (4 mg), potassium iodide (16 mg), morpholine (1 mmol) and isopropanol (5 mL) were loaded into a 10 mL glass tube. The glass tube was placed in a batch reactor at room temperature and filled with 0.4 MPa air and 1.6 MPa CO in sequence (Note: the lower and upper explosion limits of CO at RT and atmospheric pressure are 12.5% ​​and 74.2%, respectively, which is outside the explosion limit). Then, the reactor was stirred at 60 °C for 10 h. After that, the pressure was carefully released. The concentration of gold in the liquid phase was determined by inductively coupled plasma emission spectrometry (ICP, Agilent 720ES). The conversion of amine was analyzed by gas chromatography (Agilent6820). The results showed that the concentration of Au in the leaching solution reached 60 mg / mL, the gold leaching rate was 76%, the conversion of morpholine reached 93%, and the selectivity of carbamate was greater than 86%.

[0032] The reaction formula is as follows: .

[0033] Example 12 100 mg of used Au / ZnO catalyst (0.79% wt.), cuprous iodide (4 mg), potassium iodide (16 mg), morpholine (1 mmol) and tert-butyl alcohol (5 mL) were loaded into a 10 mL glass tube. The glass tube was placed in a batch reactor at room temperature and filled with 0.4 MPa air and 1.6 MPa CO in sequence (Note: the lower and upper explosion limits of CO at RT and atmospheric pressure are 12.5% ​​and 74.2%, respectively, which is outside the explosion limit). Then, the reactor was stirred at 60 °C for 10 h. After that, the pressure was carefully released. The concentration of gold in the liquid phase was determined by inductively coupled plasma emission spectrometry (ICP, Agilent 720ES). The conversion of amine was analyzed by gas chromatography (Agilent6820). The results showed that the concentration of Au in the leachate reached 23.5 mg / mL, the gold leaching rate was 30%, the conversion of morpholine reached 60%, and the selectivity of carbamate was greater than 72%.

[0034] The reaction formula is as follows: .

[0035] In summary, the method provided by the present invention for leaching gold from waste heterogeneous gold-based catalysts and co-producing carbonyl compounds does not use highly toxic cyanide, strong acid or strong oxidant; the copper salt and iodine salt used can be recycled in the subsequent separation process; and useful chemicals such as urea, carbamate and carbonate (dimethyl carbonate) with added value can be generated by utilizing amines or alcohols which are widely available and inexpensive.

Claims

1. A method for leaching gold from waste heterogeneous gold-based catalysts and co-producing carbonyl compounds, characterized in that: The method comprises adding the waste multiphase gold-based catalyst together with copper salt, iodine salt and at least one of amine or alcohol compounds into a reaction kettle, and reacting them at room temperature to 100°C for 2 to 24 hours in a carbon monoxide / air atmosphere to achieve gold leaching recovery and the generation of carbonyl compounds.

2. A method for leaching gold from waste heterogeneous gold-based catalysts and co-producing carbonyl compounds as claimed in claim 1, characterized in that: The waste multiphase gold-based catalyst is a multiphase gold-based catalyst that uses metal oxide as a carrier to load elemental gold.

3. A method for leaching gold from waste heterogeneous gold-based catalysts and co-producing carbonyl compounds as claimed in claim 2, characterized in that: The waste multiphase gold-based catalyst is one of the used Au / ZnO catalyst, Au / Ga2O3 catalyst, Au / Al2O3 catalyst, Au / TiO2 catalyst, Au / CeO2 catalyst or Au / SiO2 catalyst.

4. A method for leaching gold from waste heterogeneous gold-based catalysts and co-producing carbonyl compounds as claimed in claim 1, characterized in that: The copper salt is at least one of cupric chloride, cuprous chloride, cupric bromide, cuprous bromide, cuprous iodide, cupric nitrate, copper sulfate or copper acetate, and the usage amount is 1% to 20% of the molar content of gold.

5. A method for leaching gold from waste heterogeneous gold-based catalysts and co-producing carbonyl compounds as claimed in claim 1, characterized in that: The iodized salt is at least one of sodium iodide, potassium iodide, lithium iodide, and quaternary ammonium iodide, and the usage amount is 5% to 20% of the gold molar content.

6. A method for leaching gold from waste heterogeneous gold-based catalysts and co-producing carbonyl compounds as claimed in claim 1, characterized in that: The structural formula of the amine compound is: , wherein R1 and R2 are respectively one of hydrogen, substituted or unsubstituted alkyl, aromatic or non-aromatic cyclic compounds containing or not containing heteroatoms, and the usage amount is 50 to 2000 times the molar content of gold.

7. A method for leaching gold from waste heterogeneous gold-based catalysts and co-producing carbonyl compounds as claimed in claim 1, characterized in that: The alcohol compound is one of methanol, ethanol, isopropanol, tert-butanol, butanol, isobutanol or sec-butanol, and the usage amount is 50 to 2000 times the gold molar content.

8. A method for leaching gold from waste heterogeneous gold-based catalysts and co-producing carbonyl compounds as claimed in claim 1, characterized in that: The volume ratio of carbon monoxide to air in the carbon monoxide / air atmosphere is 4:1 ~10:1, and the gas pressure is 0.5MPa ~ 4MPa.

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