A method for recovering rhodium from waste catalyst produced in a carbonyl synthesis acetic acid process

Abstract

The present invention provides a method for recovering rhodium from waste catalysts produced in the carbonyl synthesis of acetic acid process, comprising the following steps: S1: Pretreatment of the waste catalyst: 1) Dissolution of the viscous waste catalyst: Dissolving the viscous waste catalyst with alcohol to obtain dissolved waste catalyst; 2) Pretreatment of the viscous waste catalyst before entering the furnace: Mixing the dissolved waste catalyst with a protective agent to obtain a mixture of the waste catalyst and the protective agent; S2: Staged calcination: Staged calcination of the waste catalyst and protective agent mixture; S3: Activation of the calcined material: Activating elemental rhodium and rhodium oxide with zinc powder to increase the activity of the insoluble rhodium metal and allow it to be leached out of aqua regia, with the leachate then entering a separation and purification process. The present invention is characterized by effectively reducing rhodium calcination losses, preventing excessive combustion and tank overflow, and improving rhodium recovery rates.

Description

Technical Field

[0001] The invention belongs to the technical field of hazardous waste disposal and relates to a method for recovering rhodium from waste catalysts generated in a carbonyl synthesis acetic acid process. Background Art

[0002] Acetic anhydride is an important organic chemical raw material, primarily used in cellulose acetate, cigarette filters, film, textile fibers, and celluloid plastics. It can also be used as a pharmaceutical and dye intermediate, and has important applications in fragrances. The carbonyl synthesis of acetic anhydride from methyl acetate offers low energy consumption and low cost, making it suitable for large-scale production and the predominantly used industrial production process. Among the catalysts used in the carbonyl synthesis of acetic anhydride, the iodine-promoted rhodium-based complex catalytic system is relatively well-researched and is currently the most widely used industrial catalyst for the carbonyl synthesis of acetic acid and acetic anhydride. The carbonyl metal rhodium is a rhodium-containing compound such as rhodium iodide or rhodium chloride, the halogen compound is primarily methyl iodide, and the lithium is lithium iodide or lithium acetate. The precious metal rhodium is expensive and has significant recycling value.

[0003] The carbonylation process produces a high-molecular-weight residue (commonly known as tar). Tar contains hundreds of compounds that can reduce catalyst activity and even deactivate the catalyst envelope. Deactivated catalyst appears black and viscous, with a strong acetic odor. Spent rhodium catalyst, largely composed of tar, easily expands during calcination, overflowing the calcination vessel and producing a large amount of smoke, which can easily lead to rhodium loss during calcination.

[0004] "Technical Progress in Recovery of Rhodium from Carbonyl Synthesis of Acetic Acid to Produce Rhodium Triiodide" introduces a method for recovering rhodium from waste discharged from an acetic acid synthesis unit produced using a rhodium-based catalyst and converting it into rhodium triiodide that can be used in the unit. The description is rather general, only introducing conventional treatment and separation and purification methods for rhodium, without providing a detailed description of the process.

[0005] "Recovery of Rhodium from Spent Rhodium Catalyst for Low-Pressure Oxosynthesis of Propylene and Purification of Rhodium Trichloride" uses a molecular distillation apparatus to concentrate the spent rhodium catalyst solution from low-pressure propylene oxosynthesis, separating solvents such as butyraldehyde and its polymers, and triphenylphosphine, resulting in a high-concentration rhodium slag with a rhodium content of 7% to 10%. The resulting rhodium slag is treated with mixed acid to carbonize the organic matter to produce rhodium acid. The rhodium acid is then neutralized, acidified with hydrochloric acid, ion-exchanged, evaporated, crystallized, and dried to directly produce high-purity hydrated rhodium trichloride. While molecular distillation can further increase the rhodium content in the organic rhodium solution, the resulting organic product still requires proper disposal. Furthermore, the rhodium slag is digested with sulfuric acid and nitric acid, which makes it difficult to digest the high-boiling-point organic matter and poses a safety hazard, as it can easily overflow the reaction vessel.

[0006] Patent CN101757956 uses a dual-solvent extraction method, using methyl iodide (hereinafter referred to as the organic phase) and an aqueous hydrogen iodide solution (hereinafter referred to as the aqueous phase) as solvents to extract the catalyst-tar solution. This includes pretreatment and extraction of the catalyst-tar solution. The pretreatment involves evaporating and concentrating the catalyst-tar solution to remove low-boiling components such as methyl iodide, acetone, and methyl acetate. Acetic acid, acetic anhydride, and the like are also partially evaporated. After evaporation and concentration, the germanium content of the catalyst-tar solution (hereinafter referred to as the target phase) increases from 1.5 to 2.5 [kJ / kg] / min to 1.5 [kJ / kg] / min. The target phase is then transferred to a conversion tank. The organic phase is then added and stirred to obtain a target phase mixture for further extraction. After extraction, rhodium and most of the iodine enter the aqueous phase, while tar and a small amount of iodine enter the organic phase. The organic phase is then sent to a distillation tower to recover the methyl iodide and iodine. The tar solution flowing out of the kettle still needs to be incinerated.

[0007] The study "Research on Pretreatment Process for Recovering Waste Rhodium Catalysts" studied the addition of a certain amount of Ca(OH)2 to the waste rhodium catalysts produced by the 1,2-decyl alcohol industry, incineration under a set temperature program, and dissolution of the obtained rhodium-enriched material with hydrochloric acid to obtain a rhodium-containing solution. The liquid phase recovery rate of rhodium can reach 96.5%. However, due to the addition of Ca(OH)2, a large amount of calcium is present in the roasting product, which is difficult to remove simply and causes impurities to affect the subsequent separation and purification.

[0008] Patent CN1176232C discloses a method for recovering rhodium from spent rhodium catalysts in carbonyl synthesis reactions. The method uses an alkali metal or alkaline earth metal carbonate as an additive, incinerates the residue at a constant temperature of 700°C for 4 hours, and then adds sodium / potassium bisulfate to the incineration residue for a melting reaction to generate a soluble rhodium salt. This salt is dissolved with hydrochloric acid and then electrolyzed to obtain rhodium powder. The rhodium recovery rate is over 98%. This process is indeed feasible, but the sodium / potassium bisulfate melting process is inefficient and unsuitable for large-scale production.

[0009] "Method for Recovering Metal Rhodium from Waste Rhodium Catalyst Residues" mentions that the residual rhodium catalyst for carbonyl synthesis of butyl octanol is incinerated in sections through temperature control to obtain rhodium ash. The rhodium recovery rate reaches 80%~99%. Due to the large variations in the composition and content of the catalyst residue, the roasting loss of rhodium is difficult to control by simply controlling the temperature during combustion, and the roasting takes a long time.

[0010] "Extracting Rhodium Powder from Waste Rhodium Catalysts" The waste rhodium catalysts from the butanol and octanol industry were mixed with Ca(OH)2 and incinerated. The incineration temperature was kept constant at 700~800℃ for 5 hours. The rhodium ash was then refined and purified to obtain rhodium powder with a purity of 99.5%. The rhodium recovery rate was greater than 95%. However, due to the addition of Ca(OH)2, a large amount of calcium existed in the roasting product, which was difficult to remove simply and caused impurities to affect the subsequent separation and purification.

[0011] Patent CN102923796 discloses a method for recovering rhodium from waste rhodium catalysts in carbonyl synthesis to prepare hydrated rhodium chloride. Silica solid is added as an adsorbent to the waste rhodium catalyst in the carbonyl synthesis reaction, and the mixture is subjected to temperature-controlled dry distillation and roasting. The roasting residue is dissolved with hydrochloric acid and ozone, and then impurities are removed by ion exchange. The mixture is concentrated and dried to obtain hydrated rhodium trichloride. The rhodium recovery rate is over 99%. The product after dry distillation has a reduced rhodium content due to the addition of silica. At the same time, the dry distillation product should contain a large amount of carbon deposits and still requires secondary roasting. The wet direct dissolution of rhodium residue is difficult to carry out. Systems such as aqua regia, hydrochloric acid and sodium chlorate, and hydrochloric acid and chlorine are all difficult to directly leach rhodium. Similarly, direct dissolution with hydrochloric acid and ozone has a similar effect, and the carbon in the residual residue still has excellent adsorption for the rhodium that enters the solution after leaching.

[0012] CN106319202 discloses a method for recovering rhodium from waste rhodium oxo synthesis catalysts to prepare rhodium chloride hydrate. A certain amount of carbon is added to the waste rhodium oxo synthesis catalyst, which is then placed in a high-temperature furnace. Under aerobic conditions, the catalyst is incinerated according to a specific temperature control program. The program is then held constant for a certain period of time to ensure that the material is substantially carbonized. The catalyst is then subjected to oxygen-free high-temperature roasting. After high-temperature roasting, the catalyst is isolated from air and cooled to room temperature to obtain active rhodium ash. Concentrated hydrochloric acid is added, and hydrogen peroxide is added dropwise with stirring to dissolve the active rhodium. The resulting crude rhodium chloride acid solution is filtered to remove ionic impurities such as Fe, Ni, and Ca using an ion exchange method well known in the art. The resulting solution is then concentrated and dried to obtain rhodium chloride hydrate. The resulting filter residue is then filtered to form a carbon residue, which is returned for future use. Following aerobic carbonization and oxygen-free high-temperature roasting, carbon acts as a reducing agent to reduce the rhodium. However, in oxygen-free high-temperature roasting, the amount of carbon residue after carbonization is difficult to precisely match the amount of rhodium. Too little carbon results in incomplete reduction, while too much carbon can adsorb any rhodium that enters the solution during leaching, significantly affecting the leaching rate.

[0013] In the prior art: 1) the carbonylation process produces high-molecular residues (commonly known as tar), which have high viscosity and are difficult to mix with additives added to prevent rhodium loss during roasting; 2) at the same time, if directly roasted, high-boiling-point organic matter does not ignite and burn below 350-400°C, but instead evaporates in large quantities, expanding in volume and easily overflowing the roasting vessel. When the temperature exceeds the limit, it directly ignites an open flame and produces a large amount of black smoke, resulting in significant rhodium loss during roasting.

[0014] In summary, in order to address the technical deficiencies of existing methods for recovering rhodium from spent catalysts produced by the carbonyl synthesis of acetic acid process, the present invention has designed a method for recovering rhodium from spent catalysts produced by the carbonyl synthesis of acetic acid process, which can effectively reduce rhodium roasting losses, avoid excessive combustion and overflow, and improve rhodium recovery. Summary of the Invention

[0015] The present invention aims to solve the problems existing in the prior art and provides a method for recovering rhodium from waste catalysts produced in a carbonyl synthesis acetic acid process, which can effectively reduce rhodium roasting losses, avoid overflowing from violent combustion, and improve rhodium recovery.

[0016] The purpose of the present invention can be achieved through the following technical solutions:

[0017] A method for recovering rhodium from waste catalysts produced in a carbonyl synthesis of acetic acid process.

[0018] The following steps are included:

[0019] S1 Spent catalyst pre-treatment

[0020] 1) Dissolution of viscous spent catalyst

[0021] dissolving the viscous waste catalyst with alcohol to obtain dissolved waste catalyst;

[0022] 2) Treatment of viscous spent catalyst before entering the furnace

[0023] mixing the dissolved spent catalyst with a protective agent to obtain a spent catalyst and protective agent mixture;

[0024] S2 staged roasting process

[0025] The spent catalyst and protective agent mixture is subjected to staged calcination;

[0026] S3 Activation of calcined materials

[0027] Elemental rhodium and rhodium oxide are activated by zinc powder, which increases the activity of the insoluble metal rhodium and allows it to be leached by aqua regia. The leaching liquid enters the separation and purification process.

[0028] As a further improvement of this solution, the S2 segmented roasting process specifically includes the following steps:

[0029] 1) Spontaneous combustion

[0030] After dissolving and stirring in the previous step, the viscous waste material is converted into a solid wet material. After the material is placed in a container, it is directly ignited. After ignition, as time goes by, the carbon mixed in the material begins to burn, and further carbonizes and burns the high-boiling point material. Only white smoke appears during the combustion process. The flue gas enters the treatment system, and the bag dust collector obtains a small amount of dust <1% of the material. Analysis shows that the rhodium content is <10g / t, and the roasting loss is <1‰;

[0031] 2) Rinse the primary roasting residue with hot water to remove sodium

[0032] The weight of the residual material after spontaneous combustion roasting is about 30%-50% of the total weight of the ingredients, which contains a large amount of sodium salt components and carbon deposits. The sodium salt is washed away by hot water rinsing, and rinsed 4 to 6 times with a solid-liquid ratio of 1:1 to 3 each time. The water content of the residual material is 60-80%, which is about 5-15% of the weight of the ingredients;

[0033] 3) High temperature roasting

[0034] The material after spontaneous combustion is subjected to secondary high-temperature roasting to remove residual carbon deposits. The secondary roasting temperature is controlled at 650-850℃, and the weight of the material after roasting is 1-5% of the original weight.

[0035] As a further improvement of this solution, in S1, the viscous waste catalyst is dissolved by adding the viscous material into alcohol in small amounts and multiple times.

[0036] As a further improvement of this solution, in S1, the mass fraction of the viscous waste catalyst is a, and the mass fraction of the alcohol is b, satisfying the quantitative relationship: b:a=0.8:1~1.2:1.

[0037] As a further improvement of this solution, in S2, the protective agent is a mixture of carbon and carbonate;

[0038] As a further improvement of this solution, in S2, the carbon in the protective agent is any one or more of activated carbon, charcoal, and sawdust.

[0039] As a further improvement of this solution, in S2, the carbonate in the protective agent is any one or more of sodium salt and potassium salt.

[0040] As a further improvement of this solution, in S2, in the protective agent, the mass fraction of carbon is c, and the mass fraction of carbonate is d, satisfying the quantitative relationship: c:d=1:0.1~0.5:0.1~0.5.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] 1) In S1 1), the dissolution operation of the viscous waste catalyst requires adding the material (viscous waste catalyst) to the alcohol in batches for dissolution, and adding a small amount of material into the alcohol each time. After the small amount of material is dissolved, continue to add the material;

[0043] 2) In S1 2), the addition of the protective agent makes:

[0044] Ⅰ The carbon in the protective agent can absorb and dissolve the alcohol solution in the high-organic waste catalyst, which helps the combustion in the next step. The alcohol and the material are fully mixed and dissolved in the previous step, so that the material can be directly ignited;

[0045] Ⅱ Furthermore, materials such as sawdust can absorb the catalyst and act as a carrier to disperse it, thus preventing a large amount of catalyst from accumulating and expanding at high temperatures.

[0046] Ⅲ It is common practice to use hydroxides or carbonates of alkali metals or alkaline earth metals as protective agents during the roasting process of precious metal waste. However, calcium salts are difficult to dissolve after roasting, so sodium salts or potassium salts are used. However, sodium hydroxide or potassium hydroxide is prone to hardening during roasting, and the high alkalinity is also difficult to remove by water washing;

[0047] Ⅳ During the spontaneous combustion process, the alcohol burns and ignites the wood chips, making the entire spontaneous combustion process continuous and stable without the occurrence of open flame, high temperature and intense combustion;

[0048] 3) During the self-roasting process, the material contains alcohol and can be ignited directly. At the beginning, the alcohol burns with an open flame. After the alcohol burns, the sawdust is ignited, and some organic matter is also carbonized and ignited, appearing a dark red color similar to that of coal combustion. During the whole process, the material is properly turned over to allow sufficient contact with the air. The combustion process can be understood as: alcohol combustion - self-ignition of sawdust + carbonization of catalyst - combustion of carbonized matter). Due to the presence of sodium carbonate, the material will become sticky and agglomerated after a certain stage of roasting, wrapping the roasted product.

[0049] 4) During the water washing process of the primary roasting residue, the presence of the sodium carbonate protective agent causes the roasting product to agglomerate, encapsulating a portion of the carbonized unburned material. The sodium salt is removed by hot water washing. Because a very small amount of rhodium reacts with the sodium carbonate during the roasting process, it enters the solution during the hot water washing process, with a content of 3-10g / t. To further reduce dissolution losses, the reducing agent hydrazine hydrate is added in conjunction with the water washing (at a dosage of 0.5-1% of the solution volume), and the rhodium entering the solution is reduced to <1g / t. Furthermore, the purpose of the secondary roasting is to burn off the residual carbon deposits from the roasting process.

[0050] 5) During the fragmentation and activation process, the fragmentation activation dissolution method is used to treat the insoluble precious metal rhodium, which has a high dissolution rate. Platinum group metals are alloyed with a fragmentation agent, and the alloy is acid-leached to remove the active metals. The remaining insoluble platinum group metals are converted into a highly dispersed, highly active, and easily soluble powder. Leaching is then performed using aqua regia or aqueous chlorination, producing a highly concentrated precious metal solution for recycling and purification. Common fragmentation agents include zinc, tin, aluminum, and lead (CN102796864). Lead is more toxic than the other metals, and the acid-soluble products of aluminum and tin are less soluble than zinc, requiring dilution for filtration. Therefore, zinc is further selected as a fragmentation agent. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 This is a process flow diagram of a method for recovering rhodium from waste catalysts produced in the carbonyl synthesis of acetic acid process of the present invention; DETAILED DESCRIPTION

[0052] The technical solution of the present invention is further described below in conjunction with the embodiments and drawings.

[0053] like Figure 1 As shown, Figure 1 A process flow diagram of a method for recovering rhodium from spent catalyst produced in a carbonyl synthesis of acetic acid process; Example

[0054] Take 500g of raw material, put it into a 5L evaporating dish, and place it in a muffle furnace for heating and calcining. The heating rate of the muffle furnace is 50℃ / h. When the temperature rises to 100℃, the viscous material has liquefied and bubbled, and white smoke is generated. When the temperature rises to 150-200℃, the liquefied material expands, and a large amount of white smoke continues to be generated. As the temperature continues to rise, the material expands and overflows the vessel. No open flame is generated during the process. Example

[0055] Take 500g of raw material, put it into a 5L evaporating dish, and put 5% of the weight of the material into broken porcelain pieces, put it into a muffle furnace for heating and roasting, the muffle furnace heating rate is 50℃ / h, and there is no obvious expansion before the temperature rises to 10-150℃, but after rising to 350-380℃, the material expands but does not overflow the vessel. When the temperature rises to 380-400℃, the material suddenly ignites and burns violently, with a large amount of black smoke generated. The temperature rises to 550℃ on its own. After the muffle furnace is closed to allow the spontaneous combustion to end, the inside and outside of the furnace and the vessel have been blackened and a large amount of carbon produced by incomplete combustion fills the furnace and floats. At the same time, the material in the vessel is not completely roasted. Reopen the muffle furnace, after heating to 400℃, the carbon deposit combustion can be clearly observed. After heating to 700℃ and roasting for 4h, the burn loss is 99.39%. The roasted product is brown and loose. Sample analysis shows that the roasting Rh loss is 14.39%. Example

[0056] Take 500g of raw material, add 500mL of alcohol to dissolve it, mix it and ignite it, producing a lot of white smoke. The open flame will go out by itself after burning for about 10-15min, and there is no dark red spontaneous combustion phenomenon after carbonization. Put it into the muffle furnace for heating and burning. The heating rate of the muffle furnace is 50℃ / h. White smoke appears during the process. When the temperature is raised to 450℃, open flame and a lot of black smoke appear. The temperature rises to 550℃ by itself. After the muffle furnace is closed and the spontaneous combustion ends, the inside and outside of the furnace and the vessel have been blackened and a large amount of carbon produced by incomplete combustion is floating in the furnace. At the same time, the material in the vessel is not completely roasted. Reopen the muffle furnace, heat it to 400℃, and the carbon deposit combustion can be clearly observed. After heating to 700℃ and keeping warm for 4h, the burn loss is 99.56%. The roasted product is brown and loose. Sample analysis shows that the roasting Rh loss is 12.58%. Example

[0057] Take 500g of raw material, add 500mL of alcohol to dissolve it, and add 150g of sawdust, mix well, and ignite it to produce a large amount of white smoke. The open flame goes out after burning for 10-15 minutes, but a dark red dark flame appears on the entire surface. Keep turning it over to keep the dark flame burning. After about 30 minutes, there is no dark red burning phenomenon. Put it into a muffle furnace and heat it for secondary roasting until the temperature reaches 700℃. No open flame is produced, only white smoke. Open the furnace door and turn the material over until the white smoke disappears. It takes about 1-2 hours. After roasting, the material is brown and loose, with a burn loss of 99.27%. Samples were sent for analysis, and the Rh loss during roasting was 2.33%. Example

[0058] Take 500g of raw material, add 500mL of alcohol to dissolve it, and add 300g of sawdust, mix well, and ignite. The phenomenon is the same as in Example 4. After about 30min without dark red burning phenomenon, put it into a muffle furnace and heat it for secondary roasting until the temperature reaches 700℃. No open flame is generated, only white smoke is generated. Open the furnace door and turn the material over until the white smoke disappears. It takes about 1-2h. After roasting, the material is brown and loose, with a burn loss of 99.14%. Sample analysis shows that the Rh loss during roasting is 2.17%. Example

[0059] Take 500g of raw material, add 500mL of alcohol to dissolve it, and add 500g of sawdust, mix well, ignite, and produce a lot of white smoke. The open flame goes out after burning for 10-15 minutes, but a dark red dark flame appears on the entire surface. Keep turning it over to keep the dark flame burning. After the end, it can be clearly observed that some sawdust has not been carbonized and burned. Put it into a muffle furnace and heat it for a second roasting until the temperature reaches 700℃. No open flame is produced, only white smoke. Open the furnace door and turn the material over until the white smoke disappears. It takes about 2.5h. After roasting, the material is brown and loose, with a burn loss of 98.93%. Samples were sent for analysis, and the Rh loss during roasting was 1.62%. Example

[0060] Take 500g of raw material, add 500mL of alcohol to dissolve it, and add 150g of sawdust and 150g of sodium carbonate. After mixing, ignite it to produce a large amount of white smoke. The open flame goes out after burning for 10-15 minutes, but a dark red dark flame appears on the entire surface. Keep turning it to keep the dark flame burning. During the combustion process, the material begins to agglomerate into particles. After about 30 minutes, there is no dark red burning phenomenon. Put it into a muffle furnace and heat it for secondary roasting until the temperature reaches 700℃. No open flame is produced, only white smoke. Open the furnace door and turn the material until the white smoke disappears. It takes about 2 hours. After roasting, the material is gray small particles with a burn loss of 46.21% (calculated based on 500g of raw material). Hydrazine hydrate is added to hot water as a protective agent to wash the sodium salt in the roasting product. It is roasted twice in a muffle furnace with a total burn loss of 98.79% (calculated based on 500g of raw material). Sample analysis shows that the Rh loss during roasting is 0.11%. Example

[0061] Take 500g of raw material, add 500mL of alcohol to dissolve it, and add 300g of sawdust and 300g of sodium carbonate. After mixing, ignite it to produce a large amount of white smoke. The open flame goes out after burning for 10-15 minutes, but a dark red dark flame appears on the entire surface. Keep turning it to keep the dark flame burning. During the combustion process, the material begins to agglomerate into particles. After about 30 minutes, there is no dark red burning phenomenon. Put it into a muffle furnace and heat it for secondary roasting until the temperature reaches 700℃. No open flame is produced, only white smoke is produced. Open the furnace door and turn the material until the white smoke disappears. It takes about 2 hours. After roasting, the material is gray small particles with a burn loss of 33.64% (calculated based on 500g of raw material). Hydrazine hydrate is added to hot water as a protective agent to wash the sodium salt in the roasting product. It is roasted twice in a muffle furnace with a total burn loss of 97.59% (calculated based on 500g of raw material). Sample analysis shows that the Rh loss during roasting is 0.13%.

[0062] The method for recovering rhodium from waste catalysts produced by the carbonyl synthesis of acetic acid process of the present invention has the following advantages: 1) alcohol is used as a solvent for the waste catalyst, and after dissolution, a protective agent such as sodium carbonate or potassium carbonate and a suitable amount of carbon are added as protective agents to reduce rhodium roasting losses and avoid problems such as violent combustion and overflowing the tank; 2) alcohol is used as an ignition agent during spontaneous combustion roasting to ignite carbon in the mixture, causing spontaneous combustion and carbonization of the waste catalyst. The combustion process is smooth, and the organic components in the waste catalyst are mainly volatilized and carbonized; 3) the spontaneous combustion roasting product is washed with water to remove a large amount of sodium salt or potassium salt, and after a second high-temperature roasting to remove carbon deposits, the remaining roasting product is 1-5% of the weight of the original waste, greatly increasing the rhodium content. A soluble rhodium material can be obtained through a fragmentation and activation technology, and then enters a dissolution and separation purification process.

[0063] The embodiments described herein are merely preferred embodiments of the present invention, but the scope of the present invention is not limited thereto. Any modification, supplement, or replacement of the embodiments described herein by those skilled in the art shall fall within the scope of the present invention.

Claims

1. A method for recovering rhodium from waste catalysts produced in a carbonyl synthesis of acetic acid process, characterized in that: The following steps are included: S1 Spent catalyst pre-treatment 1) Dissolution of viscous spent catalyst dissolving the viscous waste catalyst with alcohol to obtain dissolved waste catalyst; 2) Treatment of viscous spent catalyst before entering the furnace mixing the dissolved spent catalyst with a protective agent to obtain a spent catalyst and protective agent mixture; The protective agent is a mixture of carbon and carbonate; S2 staged roasting process The spent catalyst and protective agent mixture is subjected to staged calcination; S3 Activation of calcined materials Elemental rhodium and rhodium oxide are activated by zinc powder, which increases the activity of the insoluble metal rhodium and allows it to be leached out by aqua regia. The leaching liquid enters the separation and purification process. S2 staged roasting process, specifically including the following steps: 1) Spontaneous combustion After dissolving and stirring, the viscous waste material is converted into a solid wet material. After the material is placed in a container, it is directly ignited. As time passes after ignition, the carbon mixed in the material begins to burn, and further carbonizes and burns the high-boiling point material. Only white smoke appears during the combustion process, and the flue gas enters the treatment system. The bag dust collector obtains dust removal amount <1% of the material. Analysis shows that the rhodium content is <10g / t, and the roasting loss is <1‰; 2) Rinse the primary roasting residue with hot water to remove sodium The residual weight of the material after spontaneous combustion roasting is 30%-50% of the weight of the ingredients, which contains a large amount of sodium salt components and carbon deposits. The sodium salt is washed away by hot water rinsing. Rinse 4 to 6 times with a solid-liquid ratio of 1:1 to 3 each time. The residual material contains 60-80% water, which is 5-15% of the weight of the ingredients. 3) High temperature roasting The material after spontaneous combustion is subjected to secondary high-temperature roasting to remove residual carbon deposits. The secondary roasting temperature is controlled at 650-850℃, and the weight of the material after roasting is 1-5% of the original weight.

2. The method for recovering rhodium from waste catalyst produced by the carbonyl synthesis of acetic acid process according to claim 1, characterized in that: In S1, the viscous waste catalyst is dissolved by adding the viscous material into alcohol in small amounts and multiple times.

3. The method for recovering rhodium from waste catalyst produced by the carbonyl synthesis of acetic acid process according to claim 1, characterized in that: In S1, the mass fraction of the viscous waste catalyst is a, and the mass fraction of the alcohol is b, which satisfies the quantitative relationship: b:a=0.8:1~1.2:

1.

4. The method for recovering rhodium from waste catalyst produced by the carbonyl synthesis of acetic acid process according to claim 1, characterized in that: In S2, the carbon in the protective agent is any one or more of activated carbon, charcoal, and sawdust.

5. The method for recovering rhodium from waste catalyst produced by the carbonyl synthesis of acetic acid process according to claim 1, characterized in that: In the protective agent, the carbonate is any one or more of sodium salt and potassium salt.

6. The method for recovering rhodium from waste catalyst produced by the carbonyl synthesis of acetic acid process according to claim 1, characterized in that: In the protective agent, the mass fraction of carbon is c, and the mass fraction of carbonate is d, satisfying the quantitative relationship of c:d=0.1~0.5:0.1~0.

5.

7. The method for recovering rhodium from waste catalyst produced by the carbonyl synthesis of acetic acid process according to claim 1, characterized in that: In S3, material: zinc powder = 1:4~6.

8. The method for recovering rhodium from waste catalyst produced by the carbonyl synthesis of acetic acid process according to claim 1 or 7, characterized in that: In S3, the activation temperature is 700~900℃ and the activation time is 4~6h.

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