Method for recovering valuable metals from spent catalysts

Abstract

To provide a method enabling recovery of valuable metal from a waste catalyst without generation of gas such as SOx or wastewater.SOLUTION: According to one embodiment of the present invention, a valuable metal recovery method comprises a leaching step in which a first inorganic compound containing VO3 is leached from a waste catalyst at a temperature lower than 100°C and under atmospheric pressure.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to a method for recovering valuable metals from spent catalysts. [Background technology]

[0002] A catalyst is a substance that activates any reaction system without reacting itself, thereby accelerating the overall reaction. It is an essential substance in the processing steps of oil refining and petrochemicals. While the amount of catalyst used in oil refining and petrochemical processes is relatively small compared to the amount of FEED (Feed-Induced Energy) used, the amount of catalyst used is gradually increasing due to the growing number of oil refining and petrochemical plants.

[0003] In particular, oil refineries and petrochemical plants use a variety of catalysts containing valuable metals such as molybdenum, vanadium, nickel, and aluminum. However, the performance of each catalyst containing these valuable metals gradually deteriorates over time, and they are replaced when they reach the end of their lifespan. Conventionally, spent catalysts that have reached the end of their lifespan have been entirely landfilled without any special treatment method, leading to soil contamination problems due to the leaching of heavy metals into groundwater. This has resulted in the problem that high-value-added valuable metals that could be used as raw materials for advanced industries are not reused but are simply discarded.

[0004] In response to the aforementioned problems, various methods have been proposed to recover valuable metals such as molybdenum and vanadium, which are precious metals, from spent catalysts that have reached the end of their lifespan in oil refining and petrochemical processes, in order to minimize soil contamination and recycle high-value-added metals that are currently dependent on imports.

[0005] However, in particular, when recovering valuable metals from desulfurization waste catalysts, conventional processes involve roasting at high temperatures and / or high pressures, leading to problems such as environmental pollution due to the generation of gases such as sulfur dioxide and excessive energy costs. Furthermore, the complex processes and the need for separate facilities resulted in economic losses.

[0006] Furthermore, the high-temperature and high-pressure processes result in nickel and aluminum being disposed of as industrial waste rather than being recovered and reused, leading to environmental pollution and significant economic losses. [Overview of the project] [Problems that the invention aims to solve]

[0007] One objective is to provide a method for recovering valuable metals from spent catalysts without generating gases such as SOx or wastewater.

[0008] One objective is to provide a method for recovering valuable metals from waste catalysts that does not require high-temperature and / or high-pressure processes for removing sulfur and other substances from waste catalysts or for leaching metal compounds.

[0009] One objective is to provide a method for recovering valuable metals from spent catalysts that can recover not only vanadium, but also molybdenum, aluminum, and nickel with high recovery rates. [Means for solving the problem]

[0010] A method for recovering valuable metals according to one aspect of the present invention comprises a spent catalyst preparation step for preparing spent catalysts, and a method for recovering VO3 from the spent catalyst prepared in the spent catalyst preparation step under conditions of a temperature of less than 100°C and atmospheric pressure. - The process includes a leaching step in which a first inorganic compound containing is leached out.

[0011] In one embodiment, the leaching step may include stirring the prepared waste catalyst in a leaching solution containing sodium hydroxide under conditions of a temperature of less than 100°C and atmospheric pressure.

[0012] In one embodiment, the leaching solution containing sodium hydroxide may be an aqueous solution of sodium hydroxide with a concentration of 3% to 20%.

[0013] In one embodiment, the leaching step may include a step of injecting oxygen or air.

[0014] As one aspect, it is preferable not to include a step of heat-treating the waste catalyst at a temperature of 100°C or higher after the step of preparing the waste catalyst and before the leaching step.

[0015] As one aspect, a precipitation step may be further included in which a salt is added to the first inorganic compound leached in the leaching step to precipitate a second inorganic compound containing VO3 -

[0016] As one aspect, the salt added in the precipitation step may be ammonium chloride.

[0017] As one aspect, a step of oxidizing the second inorganic compound precipitated in the precipitation step, adding hydrochloric acid to the generated ammonia to produce ammonium chloride, and then recycling the produced ammonium chloride may be further included.

[0018] As one aspect, a step of recovering vanadium oxide by oxidizing the second inorganic compound precipitated in the precipitation step may be further included.

[0019] As one aspect, a step of recovering any one or more selected from nickel, nickel compounds, aluminum, aluminum compounds, molybdenum, and molybdenum compounds may be further included.

Advantages of the Invention

[0020] As one effect, the method for recovering valuable metals according to one aspect of the present invention does not generate gases such as SOx and wastewater such as leaching solutions, so environmental pollution and economic costs can be significantly reduced.

[0021] As one effect, the method for recovering valuable metals according to one aspect of the present invention does not require a high-temperature and / or high-pressure step for removing sulfur or the like from the waste catalyst or leaching metal compounds, so the energy cost can be significantly reduced.

[0022] ​As an effect, the method for recovering valuable metals according to one aspect of the present invention can recover not only vanadium but also molybdenum, aluminum, and nickel at high recovery rates.

Brief Description of the Drawings

[0023] [Figure 1] It is a diagram showing a process according to one aspect of the present invention.

Modes for Carrying Out the Invention

[0024] Expressions such as "including" used in this specification should be understood as open-ended terms that encompass the possibility of including other components.

[0025] "Preferred" and "preferably" used in this specification are used for embodiments of the present invention that have certain advantages under certain conditions. However, such descriptions are not intended to exclude other embodiments from the technical scope of the present invention.

[0026] The singular forms used in this specification can be intended to include plural forms as well, unless otherwise indicated in the context.

[0027] In this specification, terms such as "first" and "second" are not used in a limiting sense but for the purpose of distinguishing one component from another.

[0028] The numerical ranges used in this specification include the lower limit value and the upper limit value, all values within that range, increments logically derived in the form and width of the defined range, all values doubly limited, and all possible combinations of the upper and lower limits of numerically defined ranges that are limited in different forms.

[0029] Unless otherwise specifically defined in this specification, values outside the numerical ranges that may occur due to experimental errors or rounding of values are also included in the defined numerical ranges.

[0030] On the other hand, each of the technical features described later relates to one embodiment for obtaining the effect intended by the present invention described above. That is, a method for recovering valuable metals according to one embodiment of the present invention can produce the above-mentioned effect by including the technical features according to the embodiment described later.

[0031] This invention relates to a method for recovering valuable metals from spent catalysts.

[0032] In the oil refining and petrochemical industries, catalysts are used to smoothly remove sulfur and other substances from crude oil. Typically, catalysts have a lifespan of 3 to 5 months and are replaced periodically, but this can generate waste catalyst.

[0033] The aforementioned waste catalyst may contain vanadium, as well as one or more valuable metals selected from molybdenum, cobalt, aluminum, and nickel.

[0034] In this specification, the recovery of valuable metals means not only the recovery of the valuable metals themselves, but also the recovery of them as a marketable compound containing the valuable metals.

[0035] In this invention, compounds containing the valuable metal and / or valuable metals can be extracted and recovered using a simple, economical, and environmentally friendly method.

[0036] Examples of compounds containing the aforementioned valuable metals include (NH4)VO3 or vanadium pentoxide (V2O5). These compounds, or the vanadium contained therein, can be used as raw materials for alloy steels, aerospace, automotive, and electronic materials, and as raw materials for next-generation REDOX batteries.

[0037] One example of a compound containing valuable metals is molybdenum trioxide (MoO3). This compound, or the molybdenum contained therein, can be used as a raw material for special alloy steels, for military applications, or for industrial machinery.

[0038] Nickel oxide (NiO) is an example of a compound containing valuable metals. This compound, or the nickel contained therein, can be used as a raw material for the positive electrode material of batteries or as a raw material for stainless steel heat-resistant steel, etc.

[0039] Examples of compounds containing valuable metals include aluminum oxide (Al2O3) or aluminum hydroxide (Al(OH)3). These compounds, or the aluminum contained therein, can be used as raw materials for packaging (cans, foil) and building materials.

[0040] An example of a compound containing a valuable metal is a cobalt-containing oxide. This compound, or the cobalt contained therein, can be used as a raw material for the positive electrode material of a secondary battery, among other things.

[0041] First, the waste catalyst preparation process described above is carried out to prepare the waste catalyst.

[0042] The prepared waste catalyst may be a waste catalyst used for desulfurization.

[0043] In one embodiment, during the preparation step for the spent catalyst, the spent catalyst may be pulverized alone or together with an aqueous solution containing sodium hydroxide. The size of the pulverized spent catalyst may be 100 μm or less, and the pulverizer used for pulverization may be any commonly used pulverizer such as a ball mill.

[0044] Next, the waste catalyst prepared in the waste catalyst preparation step is subjected to VO3 at temperatures below 100°C, 98°C or below (or less), 95°C or below (or less), more preferably 92°C or below (or less), 50°C or above (or greater), 60°C or above (or greater), 70°C or above (or greater), 80°C or above (or greater), more preferably 85°C or above (or greater). - A leaching process is performed to extract a first inorganic compound containing the specified substance.

[0045] Furthermore, the leaching process is carried out under normal pressure conditions.

[0046] Here, "atmospheric pressure conditions" refers to the pressure under normal circumstances when no vacuum or pressurizing equipment such as vacuum pumps is being used. For example, this corresponds to approximately 760 mmHg, which is typical atmospheric pressure.

[0047] This invention has the advantage that, since the reaction takes place at a temperature below the boiling point of water, the reactor pressure automatically becomes less than 1 atmosphere, eliminating the need for a pressure-resistant reactor and allowing the use of an inexpensive reactor made of plastic material.

[0048] In one embodiment, the leaching step may include stirring the prepared waste catalyst in a leaching solution containing sodium hydroxide under conditions of a temperature of less than 100°C and atmospheric pressure.

[0049] In a more specific embodiment, a wet smelting process can be carried out while stirring a leachate containing sodium hydroxide, for example, an aqueous sodium hydroxide solution, with waste catalyst.

[0050] As a more preferred example, the mass ratio of the leaching solution containing added sodium hydroxide to the mass of the waste catalyst may be 1 to 40, 5 to 30, or 10 to 20.

[0051] One aspect of the present invention involves leaching the sodium hydroxide aqueous solution under the aforementioned temperature and pressure conditions, thereby preventing the discharge of sulfuric acid gas, or recovering and reusing the sodium hydroxide aqueous solution as is, thereby preventing the generation of wastewater.

[0052] As a more preferred example, the leaching solution containing sodium hydroxide may be an aqueous sodium hydroxide solution with concentrations of 3% or more, 4% or more, 5% or more, 20% or less, 15% or less, 10% or less, or 7% or less. The present invention makes it possible to recover valuable metals in high yield under low temperature and atmospheric pressure conditions by adjusting the aqueous sodium hydroxide solution to the above concentrations and using it as a leaching solution.

[0053] In one embodiment, the leaching step may further include a step of injecting oxygen or air while leaching as a leaching solution containing sodium hydroxide under conditions of a temperature of less than 100°C and atmospheric pressure.

[0054] As an intermediate product of the leaching process, vanadium in a trivalent oxidation state may be formed. For example, the intermediate product of the leaching process is NaVO2.

[0055] In one embodiment, VO3 leached in the leaching process - The first inorganic compound containing it is sodium vanadate (Meta),NaVO3.

[0056] Next, the leaching step involves the VO3 leached in the leaching step. - The process may further include a filtration step of filtering out the first inorganic compound containing the first inorganic compound. The filtration step is not particularly limited, as long as it is performed by a usable method.

[0057] In one embodiment, the filtration step may separate the solid phase containing nickel, aluminum, cobalt, etc. from the liquid phase in which vanadium, molybdenum, etc. are dissolved.

[0058] In one embodiment, nickel, aluminum, cobalt, etc., present in the solid solution as the solid phase during the filtration step may be extracted in a separate form.

[0059] Next, the VO3 leached in the leaching process - A salt is added to the first inorganic compound containing VO3 - A precipitation step may be further performed to precipitate a second inorganic compound containing the salt. In this case, it may be preferable to add an acidic substance such as hydrochloric acid before adding the salt to adjust the pH of the solution to 7.

[0060] As an example, the salt added in the precipitation process is ammonium chloride.

[0061] At this time, more preferably, the ammonium chloride is added in a molar amount of 2 to 4 times, or 2.5 to 3.5 times, the number of moles of vanadium leached in the leaching step.

[0062] As an example, the precipitated VO3 - The second inorganic compound containing is ammonium metavanadate ((NH4)VO3).

[0063] As an example, the precipitation step is represented by the following reaction formula 1.

[0064] <Reaction formula 1> NaVO3 + NH4Cl → (NH4)VO3↓ + NaCl

[0065] In one aspect, the precipitation step may further include a filtration step of filtering the precipitated second inorganic compound. The filtration step is not particularly limited as long as it is a usable method.

[0066] Next, it may further include a step of recovering vanadium oxide by oxidizing the second inorganic compound precipitated in the precipitation step.

[0067] As an example, the vanadium oxide may be vanadium(V) oxide (V2O5). As long as the vanadium oxide can be recovered from the second inorganic compound containing the precipitated VO3 - The method is not particularly limited.

[0068] In one aspect, it is not necessary to include a step of heat-treating the waste catalyst at a temperature of 100°C or higher after the step of preparing the waste catalyst and before the leaching step.

[0069] The present invention does not require a separate pretreatment step including a process of removing and oxidizing oil or sulfur contained in the waste catalyst.

[0070] Conventional processes involve a roasting step to remove oil or sulfur. This requires separate equipment for the roasting step. However, the present invention does not involve a roasting step of the spent catalyst at a temperature of 100°C or higher to remove sulfur or other substances after the preparation step and before the leaching step. Therefore, separate equipment is not required, and gas emissions such as SOx are almost negligible, making it environmentally friendly.

[0071] Furthermore, as described above, the present invention provides VO3 under conditions of a temperature of less than 100°C and atmospheric pressure. - Since a first inorganic compound containing is leached out, the leaching process does not include a step of heat-treating the waste catalyst at a temperature of 100°C or higher.

[0072] In a more specific embodiment, it is not necessary to include a step of heat-treating the waste catalyst at 100°C or higher, 200°C or higher, 300°C or higher, 400°C or higher, 500°C or higher, 600°C or higher, 700°C or higher, or 800°C or higher before or during the preparation step of the waste catalyst and before the leaching step.

[0073] In a more preferred embodiment, the process may further include a step of oxidizing the second inorganic compound precipitated in the above-described precipitation step, adding hydrochloric acid to the resulting ammonia to produce ammonium chloride, and then reusing the produced ammonium chloride.

[0074] In one embodiment, the present invention may further include a step of recovering one or more selected from nickel, nickel compounds, aluminum, aluminum compounds, molybdenum, and molybdenum compounds.

[0075] The step of recovering the nickel compound and / or nickel is the VO3 - A leaching step in which a first inorganic compound containing the above is leached may be followed by a separate separation step, which can be carried out by known methods. For example, nickel or nickel compounds can be extracted from the Ni / Al2O3 residue formed in the leaching step.

[0076] The step of recovering the molybdenum compound and / or molybdenum is the VO3 - The leaching step, which involves leaching out the first inorganic compound containing the above, may be followed by a separate separation step, which can be carried out by known methods.

[0077] In a more preferred embodiment, the VO3 - After the precipitation step, in which a second inorganic compound containing the above is precipitated, a step may be performed in which molybdic acid (H2MoO4) reagent is added to the extract solution from which vanadium has been recovered in an amount of 3 to 7 times, or 4 to 6 times, the number of moles relative to the number of moles of molybdenum.

[0078] Next, after adding the molybdic acid (H2MoO4) reagent, the temperature is raised to 70°C to 90°C, and the pH is adjusted to 2.5 to 3.5 while adding the acid, thereby allowing the molybdenum to be recovered.

[0079] The step of recovering the aluminum compound and / or aluminum is the VO3 - The leaching step, which involves leaching out the first inorganic compound containing the above, may be followed by a separate separation step, which can be carried out by known methods.

[0080] This invention allows for the recovery of nickel and / or aluminum without performing a roasting process of the spent catalyst and without performing a leaching process under conditions of a temperature below 100°C and atmospheric pressure.

[0081] The following describes embodiments of the present invention in more detail. [Examples]

[0082] Vanadium / molybdenum leaching process

[0083] 30g of pellet-type desulfurization waste catalyst containing the components shown in Table 1 below, generated at a South Korean oil refining company, was crushed using a ball mill.

[0084] [Table 1]

[0085] The pulverized raw material was placed in a 1L glass reactor, 360g of a 6% sodium hydroxide (NaOH) solution was added, and the mixture was stirred at a speed of 250 rpm to raise the reactor temperature to 90°C. The metal was then extracted by supplying air to the leaching solution at a rate of 300 cc / min using a gas bubbler.

[0086] The metal content in the extraction solution was analyzed using ICP (inductively coupled plasma), and the extraction rates of vanadium and molybdenum were calculated using the following formula 1.

[0087] JPEG0007853337000002.jpg19170

[0088] Table 2 below shows the analysis results of the extraction rate of each metal based on reaction time.

[0089] [Table 2]

[0090] Vanadium precipitation and recovery process

[0091] 200 g of the aforementioned extract solution containing vanadium and molybdenum was placed in a 500 ml reactor, stirred at room temperature at 200 rpm, and 5% hydrochloric acid was added to adjust the pH of the solution to 7.

[0092] Ammonium chloride (NH4Cl) powder was added to a pH-adjusted solution to allow vanadium to precipitate as ammonium vanadate (NH4VO3). The amount of ammonium chloride powder added was quantified to be three times the number of moles of vanadium contained in the solution.

[0093] The recovery rate of vanadium into ammonium vanadate (NH4VO3) was calculated using formula 2 below.

[0094] JPEG0007853337000004.jpg18170

[0095] Table 3 below shows the results of the analysis of vanadium recovery rates based on reaction time after the addition of ammonium chloride.

[0096] [Table 3]

[0097] Molybdenum precipitation and recovery process

[0098] After recovering vanadium in the vanadium precipitation step, 200 g of the remaining extract solution was placed in a 500 ml glass reactor, and while stirring at 200 rpm, five times (5 equivalents) of molybdic acid (H2MoO4) reagent relative to the molybdenum content (moles) in the extract solution was added.

[0099] The temperature of the extraction solution was raised to 80°C, and 5% hydrochloric acid was added until the pH of the solution reached 3. After the pH of the solution reached 3, the extraction solution was analyzed over time, and the molybdenum recovery rate was calculated using the same method as the vanadium recovery rate calculation formula.

[0100] Table 4 below shows the results of the analysis of molybdenum recovery rates based on reaction time.

[0101] [Table 4]

Claims

1. From a desulfurization waste catalyst, under conditions of a temperature of less than 100°C and atmospheric pressure, VO ３ － The process includes a leaching step of leaching a first inorganic compound containing, The aforementioned leaching process is, A step of stirring the waste catalyst in a leaching solution containing sodium hydroxide under conditions of a temperature below 100°C and atmospheric pressure, and The process includes the step of injecting oxygen or air. Methods for recovering valuable metals.

2. The method for recovering valuable metals according to claim 1, wherein the leaching solution containing sodium hydroxide is an aqueous sodium hydroxide solution with a concentration of 3% to 20%.

3. A method for recovering valuable metals according to claim 1, wherein the step of heat-treating the waste catalyst at a temperature of 100°C or higher prior to the leaching step.

4. After the leaching step, a salt is added to the first inorganic compound leached in the leaching step, and VO ３ － A method for recovering valuable metals according to claim 1, further comprising a precipitation step of precipitating a second inorganic compound containing the above.

5. The method for recovering valuable metals according to claim 4, wherein the salt added in the precipitation step is ammonium chloride.

6. A method for recovering valuable metals according to claim 5, further comprising the steps of oxidizing the second inorganic compound precipitated in the precipitation step, adding hydrochloric acid to the formed ammonia to produce ammonium chloride, and then reusing the produced ammonium chloride.

7. A method for recovering a valuable metal according to claim 4, further comprising a vanadium oxide recovery step, in which the second inorganic compound precipitated in the precipitation step is oxidized to recover vanadium oxide after the precipitation step.

8. The method for recovering valuable metals according to claim 4, further comprising a step of recovering one or more selected from nickel, nickel compounds, aluminum, aluminum compounds, molybdenum, and molybdenum compounds after the precipitation step.

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