KR101360292B1 - Recovery of valuable metals from spent catalyst using moderate thermophilic bacteria - Google Patents

Abstract

The present invention relates to a method for collecting valuable metals from a waste catalyst using a thermophilic bacteria and more specifically, a method for collecting valuable metals from a waste catalyst using a thermophilic bacteria comprising the steps of: cleaning a waste catalyst caused in a petroleum refining process; cultivating and growing a thermophilic bacteria for oxidizing iron and sulfur on a medium; and collecting valuable metals by putting the cleaned waste catalyst and a non-ferrous 9K medium in a bioreactor and inoculating the thermophilic bacteria to bioleach the waste catalyst. [Reference numerals] (AA) START; (BB) END; (S10) Step of cleaning a waste catalyst; (S20) Step of cultivating and growing a thermophilic bacteria for oxidizing iron and sulfur; (S30) Step of collecting valuable metals by putting the cleaned waste catalyst and a non-ferrous 9K medium in a bioreactor and inoculating the thermophilic bacteria to bioleach the waste catalyst

Description

Recovery of valuable metals from spent catalyst using moderate thermophilic bacteria}

The present invention relates to a valuable metal recovery method from the waste catalyst using a thermophilic strain.

Desulfurization waste catalysts, a byproduct of oil refineries, contain toxic components that are harmful to the human body. Therefore, attention has been focused on technology development for environmentally friendly treatment and recovery of these harmful components. Since these hazardous wastes contain heavy metals such as Mo, V, Al, Ni, Fe, it is very important to recover valuable metals before landfilling. By recovering valuable metals, we can avoid contamination problems when landfilling and recover valuable metals by applying valuable metal extraction technology using various solubilization processes to minimize landfill space. Most of the valuable metals in the desulfurization waste catalyst are recovered by the wet smelting process using acid and alkali. These processes generally result in the dissolution of gangue minerals, and valuable metal recovery and impurity treatment techniques complicate the overall process and increase processing costs. In addition, the dry smelting process has the disadvantage that excessive energy consumption, the generation of air pollution due to the emission of toxic gas (SO ₂ ) and expensive equipment is required. Recently, bioleaching technology using microbial strains has been actively utilized to recover and treat the valuable metals in an environmentally friendly manner.

Prior literatures related to this patent include a method of desulfurization of fossil fuels using iron and sulfated microorganisms in a non-ferrous 9K medium disclosed in Korean Patent Publication No. 10-1217259 (2012.12.31.).

Therefore, the present invention is bioleaching the waste catalyst generated in the petroleum refining process using thermophilic strains to the nickel (Al), aluminum (Al), iron (Fe), vanadium (V) and molybdenum It is to provide a method for recovering (Mo). In addition, it is to provide a biological leaching process that can reduce the reaction time in the valuable metal leaching reaction and reduce the cost of the pulverization treatment of the waste catalyst.

The problems to be solved by the present invention are not limited to the above-mentioned problem (s), and another problem (s) not mentioned can be understood by those skilled in the art from the following description.

In order to solve the above problems, the present invention comprises the steps of washing the desulfurization waste catalyst generated in the petroleum refining process; Incubating and growing a thermophilic strain oxidizing iron and sulfur in the medium; And injecting the washed waste catalyst and the non-ferrous 9K medium into a bioreactor and inoculating the thermophilic strain to recover the valuable metal by biological leaching, thereby recovering the valuable metal from the waste catalyst using the thermophilic strain. do.

In addition, the valuable metal recovery method from the waste catalyst using the thermophilic strain according to the present invention may further comprise the step of filtering the leaching solution after the biological leaching, the leaching residue is washed with dilute sulfuric acid, the pH of the dilute sulfuric acid Is characterized in that 1.5.

The thermophilic strain is characterized in that it is cultured while supplying iron (Fe ²⁺ ) and potassium tetrathionate (potassium tetrathionate) at pH 1.5, the thermophilic strain is sulfobacillus thermosulfidooxidan (Sulfobacillus thermosulfidooxidan), It is characterized in that at least one member selected from the group consisting of Ecidithiobacillus caldus, Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans.

PH of the medium is characterized in that 1.5-1.8.

The solids concentration in the bioreactor during the biological leaching is characterized in that 5-15% (w / v).

The pH of the biological leaching is 1.5 to 1.8, characterized in that the pH is adjusted to 2.0M sulfuric acid (H ₂ SO ₄ ).

In addition, the biological leaching reaction temperature is characterized in that 45 ± 5 ℃.

In the valuable metal recovery method from the waste catalyst using the thermophilic strain according to the present invention, the valuable metal is nickel (Ni), aluminum (Al), molybdenum (Mo), vanadium (V) and iron (Fe), Nickel (Ni) is characterized in that the leaching of 65-94%, molybdenum (Mo) 19-51% and vanadium (V) 47-90%.

According to the present invention, by using the thermophilic strain to biologically leaching the waste catalyst to increase the concentration of the solid solution to secure economic efficiency, it is possible to leach valuable metals regardless of the particle size of the waste catalyst to further crush the waste catalyst into fine particles No process is required, which saves money.

In addition, the leaching rate of nickel (Ni) and vanadium (V) can be increased in a short time by biological leaching using thermophilic strains, and iron (Fe), molybdenum (Mo) and aluminum (Al) can also be recovered. have.

1 is a flow chart showing a valuable metal recovery method from the waste catalyst using the thermophilic strain according to the present invention.
Figure 2 is an X-ray diffraction analysis (XRD) results of the desulfurized waste catalyst pulverized after washing with acetone.
3 is a graph showing changes in pH and sulfuric acid cumulative amount according to waste catalyst particle size and reaction time in a biological leaching process according to the present invention.
Figure 4 is a graph showing the redox potential change according to the particle size and reaction time of the waste catalyst during the biological leaching reaction according to the present invention.
5 is a graph showing the leaching rate of Ni, Al, Mo, V and Fe according to the reaction time in the biological leaching reaction according to the present invention.
Figure 6 is a graph showing the leaching rate of Ni, Mo and V according to the particle size and reaction time of the waste catalyst in the biological leaching reaction according to the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention and the manner of achieving it will become apparent with reference to the embodiments described in detail below with reference to the accompanying drawings.

The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. To fully disclose the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims.

In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail.

The present invention comprises the steps of washing the waste catalyst generated in the petroleum refining process;

Culturing and growing a thermophilic strain oxidizing iron and sulfur in the medium; And

It provides a valuable metal recovery method from the waste catalyst using the thermophilic strain to recover the valuable metals by injecting the washed waste catalyst and non-ferrous 9K medium in a bioreactor and inoculating the thermophilic strains biologically leached. do.

1 is a flow chart showing a valuable metal recovery method from the waste catalyst using the thermophilic strain according to the present invention. Hereinafter, the present invention will be described in detail with reference to Fig.

The valuable metal recovery method from the waste catalyst using the thermophilic strain according to the present invention includes a step (S10) of washing the waste catalyst generated in the petroleum refining process with acetone.

Catalysts are widely used in the refining industry to purify various petroleum feedstocks or to improve process efficiency. Catalytic materials, especially catalysts used in petroleum refining, usually contain chemicals such as metals, metal oxides and metal sulfides. Specifically, since the desulfurized waste catalyst disposed of from the petroleum refining industry contains valuable metals such as Al, V, Mo, Co, Ni and Fe, thermophilic strains are used in the present invention to recover them in a short time.

In the petroleum refining desulfurization catalyst according to the present invention, it is preferable to wash and remove the oil component with acetone by using a Soxhlet device because it has a large amount of oil and is not purified. .

The valuable metal recovery method from the waste catalyst using the thermophilic strain according to the present invention includes the step of culturing and growing a thermophilic strain oxidizing iron and sulfur in a medium (S20).

The microorganisms can be cultured by mixing iron and sulfur oxide microorganisms, and can be grown in 9K medium to which iron (Fe ²⁺ ) and potassium tetrathionate are added at pH 1.5. At this time, the bioreactor was stirred at 250 rpm at 45 ° C. while continuously supplying oxygen at a flow rate of 1 lpm. The microorganisms are grown until all of the Fe ²⁺ in the medium is oxidized to Fe ³⁺ . If the pH in the medium is less than 1.5, there is a problem that the growth of the thermophilic strain is inhibited, if the pH exceeds 1.8 there is a problem that Fe ³⁺ precipitates or the growth rate of the microorganism strain is lowered.

The thermophilic strains include Sulfobacillus thermosulfidooxidan, Acidithiobacillus caldus, Acidithiobacillus ferrooxidans, and Acidithiobacillus thiooxydan. It may be one or more selected from the group consisting of.

Valuable metal recovery method from the waste catalyst using the thermophilic strain according to the present invention is to put the washed desulfurized waste catalyst and non-ferrous 9K medium into the bioreactor and inoculate the thermophilic strain to recover the valuable metal by biological leaching Step S30 is included.

The solid solution concentration in the bioreactor during the biological leaching is preferably 5-15% (w / v). If the high liquid concentration is less than 5%, the leaching rate of valuable metals is high, but the content of valuable metals is low, so there is no economic feasibility of the entire process, and if it exceeds 15%, the microbial strain is killed or the leaching rate of valuable metals is reduced. There is a problem.

After the washed desulfurized waste catalyst is added and the biological leaching reaction proceeds, the pH of the medium rises at the beginning of the reaction, in which case 2.0M sulfuric acid (H ₂ SO ₄ ) is added to control the range of 1.5-1.8.

In addition, the biological leaching reaction temperature is preferably 45 ± 5 ℃. Since the strain used in the present invention is moderate thermophilic, the reaction temperature is most actively grown and active at 37-50 ° C. If the temperature exceeds 50 ℃, the activity of the strain is reduced or die.

Valuable metal recovery method from the waste catalyst using the thermophilic strain according to the present invention may further comprise the step of filtering the leaching solution after the biological leaching, the leaching residue is washed with dilute sulfuric acid. The pH of the diluted sulfuric acid is preferably 1.5.

Valuable metal recovery method from the waste catalyst using the thermophilic strain according to the present invention can recover the valuable metals of nickel (Ni), aluminum (Al), molybdenum (Mo), vanadium (V) and iron (Fe). have. In addition, it may vary according to the particle size of the spent catalyst, but after 75 hours of chemical leaching reaction, nickel (Ni) is 65-94%, molybdenum (Mo) is 19-51%, vanadium (V) is 47-90 Can be leached in%.

Example 1: Valuable metal recovery from waste catalyst using thermophilic strain

Spent catalyst

Bulk-sized catalyst was obtained from an oil refining company located in South Korea. The spent catalyst was coated with an organic substance, so it was washed with acetone using a Soxhlet apparatus to remove oil components. The washed waste catalyst was dried in an oven and ground using a mortar and sieved into three size portions (45-106 μm, 106-212 μm and greater than 212 μm). Table 1 below shows chemical compositions of waste catalysts classified by particle size analyzed by inductively coupled plasma atomic emission spectroscopy (ICP-AES). Figure 2 shows the results of X-ray diffraction analysis (XRD) of the desulfurized spent catalyst after washing with acetone. X-ray spectroscopic analysis (XRD) shows iron aluminum silicate, nickel vanadium oxide, vanadium oxide, molybdenum oxide, aluminum vanadium oxide oxide), iron molybdenum oxide, and nickel sulfide hydrate phase were identified.

Growth conditions of microorganisms

To cultivate thermophilic iron and sulfur oxidizing microorganisms, they were grown in 9K medium fed 4.5 g / l of iron (Fe ²⁺ ) and 2 M of potassium tetrathionate at pH 1.5, and cultured at 1 lpm. The batch reactor was stirred at 250 rpm at 45 ° C. while continuously supplying oxygen at a flow rate. The microorganisms were grown until Fe ²⁺ was completely oxidized to Fe ³⁺ , and after oxidation was completed, an active strain rich in iron was used for biological leaching.

Biological leaching

Leaching was carried out in a 2.5 L bioreactor containing 900 ml of non-ferrous 9K inorganic salt medium and a solids concentration of 10% (w / v). 100 ml of active strain (1 × 10 ⁷ cells / ml) was added to the reactor to inoculate. Desulfurization spent catalysts were used in three different sizes, 45-106 μm, 106-212 μm and greater than 212 μm. In addition, using a mechanical stirrer was stirred at 250 rpm, the reaction temperature was kept constant at 45 ℃ using a hot plate. If necessary, 2M of H ₂ SO ₄ was added to control the pH of the leaching solution to 1.5. Air was continuously injected into the reactor at a flow rate of 1 lpm for mixing of the leach solution.

During the biological leaching reaction, the solution was taken at regular intervals, and Ni, Al, Mo, Fe, and V were analyzed by inductively coupled plasma atomic emission spectroscopy (ICP-AES). After biological leaching, the vacuum filtered leaching residue was washed several times with dilute sulfuric acid at pH 1.5 and dried at 50 ° C. until there was no change in weight.

Analysis of Elemental Changes of Spent Catalysts and Spent Catalysts after Biological Leaching

Table 1 below shows the change in the metal and sulfur content of the leaching residue after biological leaching using the waste catalyst pulverized after washing with acetone and the thermophilic strain according to the present invention.

Particle size
(탆) Cleaned Waste Catalyst (%) Leaching residue (%) S Fe Ni Al Mo V S Fe Ni Al Mo V 45-106 4.3 0.7 3.0 16.1 2.1 9.7 2.8 0.8 0.1 15.5 3.5 15.2 106-212 4.7 0.8 2.8 17.7 2.1 10.4 2.5 0.5 0.1 14.6 3.3 14.7 Over 212 5.3 0.6 3.0 16.6 1.9 13.5 2.4 0.8 0.1 10.7 3.2 23.4

Changes in pH and Cumulative Addition of Sulfuric Acid During Biological Leaching

Biological leaching was performed in non-ferrous 9K medium at initial pH 1.5. The addition of the spent catalyst to the medium increases the pH at the beginning of the reaction, because acid is consumed by the oxides present in the spent catalyst (see Equation 1 below).

[Equation 1]

MeO + H ₂ SO ₄ → MeSO ₄ + H ₂ O

In this case, 2M H ₂ SO ₄ was added to control the pH of the medium at 1.5 to 1.8.

3 is a graph showing changes in pH and sulfuric acid cumulative amount according to waste catalyst particle size and reaction time in a biological leaching process according to the present invention. It can be seen that the pH value is in the range of 1.5 to 1.8 except for the initial reaction. The cumulative addition of 2M H ₂ SO ₄ increases up to 50 hours, but since then, the trend has been lowered as the biological leaching reaction takes place.

Effect of Redox Potential on Biological Leaching Reaction

Figure 4 is a graph showing the redox potential change according to the particle size and reaction time of the waste catalyst during the biological leaching reaction according to the present invention. The redox potential of the leaching solution before the biological leaching reaction was 580 mV, but when the desulfurization waste catalyst was added, the redox potential rapidly decreased, and the particle size exceeded 46-106 ㎛, 106-212 ㎛, and 212 ㎛ for 1.5 hours. The redox potentials of the leaching solution added with the spent catalyst were 447 mV, 430 mV and 501 mV. This is because Fe ³⁺ is reduced to Fe ²⁺ by the waste catalyst in the leaching solution, after which Fe ²⁺ is oxidized to Fe ³⁺ by the microbial strain, thereby increasing the redox potential again. The redox potentials in the 2.5 hour reaction were 494 mV, 522 mV and 539 mV, and as the leaching reaction proceeded, the increase was continued until the 23 hour reaction. The redox potential of the leachate was 591-592 mV, regardless of the particle size of the spent catalyst during 23 hours reaction, indicating that only Fe ³⁺ was present.

In addition, the redox potential is closely correlated with the particle size of the desulfurized waste catalyst, that is, the specific surface area. As shown in FIG. 4, the redox potential of the 46-106 μm waste catalyst having a small particle size, that is, a large specific surface area, was the lowest, which increased the reaction area at which Fe ³⁺ was reduced to Fe ²⁺ . This is because the Fe ³⁺ / Fe ²⁺ ratio decreases.

Leaching Rate Analysis

5 is a graph showing the leaching rate of Ni, Al, Mo, V and Fe according to the reaction time in the biological leaching reaction according to the present invention. At this time, the metal dissolved in the solution was analyzed by ICP-AES. During the leaching reaction for 25 hours, V 90%, Ni 95%, Mo 51%, Fe 62%, Al 15% were recovered, and the Al leaching rate was the lowest compared to other metals. V showed the highest leaching rate at reaction time of 25 hours, Ni and Fe at reaction time of 50 hours, and Mo at reaction time of 75 hours. The reaction time to reach the highest leaching rate for each metal was V (25 hours) <Ni (50 hours) = Fe (50 hours) <Mo (75 hours). For Al, the leaching rate continued as the leaching reaction time increased. It was increased to 58% leaching in 200 hours reaction.

It can also be seen that the leaching behavior of each metal differs depending on the reaction time. V, Mo, and Fe showed a maximum leaching rate of 90%, 60% and 64% for 25, 75 and 50 hours, and then gradually decreased as the reaction time increased. On the other hand, unlike other metals, the leaching rate did not decrease even if the reaction time was longer, and Al increased continuously.

Figure 6 is a graph showing the leaching rate of Ni, Mo and V according to the particle size and reaction time of the waste catalyst in the biological leaching reaction according to the present invention.

Leaching reactions of Ni, Mo, and V occurred rapidly at the beginning of the reaction irrespective of the size of the spent catalyst particles, and at 1.5 hours, 65-72% of Ni, 9-11% of Mo, and 47-64% of V were leached. The leaching rate of Ni was continuously increased as the reaction time increased, and 77-82% of the reaction for 7.5 hours and 86-94% of the reaction for 23 hours were leached. As the reaction time was increased, the leaching rate continuously increased, and the leaching rate was 19-22% for 7.5 hours and 45-51% for 23 hours. The leaching of V also occurred rapidly at the beginning of the reaction, and the leaching rate continuously increased with the reaction time.

In addition, it can be seen that the effect of the waste catalyst particles during the leaching reaction of Ni, Mo and V is not large, and therefore, it is not necessary to grind the waste catalyst into fine particles of less than 212 μm during leaching. In the method of recovering the valuable metal from the waste catalyst using the thermophilic strain according to the present invention, the leaching reaction proceeds abruptly at the beginning of the reaction, thereby ensuring economic feasibility according to the shortening of the reaction time. The spent catalyst can also be leached by biological means, thus reducing the cost of grinding.

Although specific embodiments of the valuable metal recovery method from the waste catalyst using the thermophilic strain according to the present invention have been described so far, it is obvious that various embodiments can be modified without departing from the scope of the present invention.

Therefore, the scope of the present invention should not be limited to the above-described embodiments, but should be determined by the scope of the appended claims and equivalents thereof.

It is to be understood that the foregoing embodiments are illustrative and not restrictive in all respects and that the scope of the present invention is indicated by the appended claims rather than the foregoing description, It is intended that all changes and modifications derived from the equivalent concept be included within the scope of the present invention.

Claims (12)

Washing the waste catalyst generated in the petroleum refining process with acetone using a Soxhlet apparatus and removing oil components contained in the waste catalyst;
Culturing and growing a thermophilic strain oxidizing iron and sulfur in the medium; And
Injecting the washed waste catalyst and non-ferrous 9K medium into a bioreactor and inoculating the thermophilic strain to recover the valuable metals by biologically leaching the valuable metals recovery method.
The method of claim 1,
The leaching solution is filtered after the biological leaching, and the leaching residue is further recovering valuable metals from the waste catalyst using a thermophilic strain, characterized in that it further comprises the step of washing with sulfuric acid.
3. The method of claim 2,
The pH of the sulfuric acid is a valuable metal recovery method from the waste catalyst using a thermophilic strain, characterized in that 1.5.
The method of claim 1,
The thermophilic strain is recovered from the waste catalyst using a thermophilic strain, characterized in that cultured while supplying iron (Fe ²⁺ ) and potassium tetrathionate (potassium tetrathionate) at pH 1.5.
The method of claim 1,
PH of the medium is 1.5-1.8 recovery of valuable metals from the waste catalyst using a thermophilic strain, characterized in that.
The method of claim 1,
The thermophilic strains include Sulfobacillus thermosulfidooxidan, Acidithiobacillus caldus, Acidithiobacillus ferrooxidans, and ACidithiobacillus thiooxydan. The valuable metal recovery method from the waste catalyst using a thermophilic strain, characterized in that at least one member selected from the group consisting of.
The method of claim 1,
The solid-liquid concentration in the bioreactor during the biological leaching is 5-15% (w / v) recovery method of valuable metals from the waste catalyst using a thermophilic strain.
The method of claim 1,
PH of the biological leaching method for recovering valuable metals from the waste catalyst using a thermophilic strain, characterized in that 1.5 to 1.8.
9. The method of claim 8,
Said pH is 2.0M sulfuric acid (H ₂ SO ₄ ) characterized in that the recovery of valuable metals from the waste catalyst using a thermophilic strain, characterized in that.
The method of claim 1,
When the biological leaching reaction temperature is 45 ± 5 ℃ valuable metal recovery method from the waste catalyst using a thermophilic strain, characterized in that.
The method of claim 1,
The valuable metal is nickel (Ni), aluminum (Al), molybdenum (Mo), vanadium (V) and iron (Fe) recovery method of valuable metals from the waste catalyst using a thermophilic strain, characterized in that.
12. The method of claim 11,
The recovery of valuable metals from the spent catalyst using a thermophilic strain characterized in that the nickel (Ni) is 65-94%, molybdenum (Mo) is 19-51% and vanadium (V) is leached to 47-90% Way.

Images