KR101217259B1 - Method for desulfurization of fossil fuels using iron and sulfur oxidising microorganism in iron free 9k medium - Google Patents

Abstract

PURPOSE: A desulfurizing method of fossil fuel using iron and sulfur oxidizing microorganisms in an iron free 9k medium is provided to implement operational processes using microorganisms at low cost. CONSTITUTION: A desulfurizing method of fossil fuel includes the following steps: microorganism strains, which oxidize iron and sulfur, are grown in an iron-based 9K medium; fossil fuel containing iron pyrite is added into an iron free 9K medium, and the microorganism stains are inoculated into the iron free 9K medium to precipitate and remove sulfur; carbon dioxide and oxygen are respectively supplied to the iron-based 9K medium and the iron free 9K medium. The iron free 9K medium includes (NH_4)_2·SO_4, KCl, K_2HPO_4, MgSO_4·7H_2O, and Ca(NO_3)_2·4H_2O dissolved in distilled water. The microorganisms are Acidithiobacillus ferroxidans(ATCC Nos. 23270). [Reference numerals] (AA) Start; (BB) End; (S110) Growing iron and sulfur oxidizing microorganisms in an iron-based 9K medium; (S120) Inoculating microorganism stains, precipitating and removing sulfur by adding fossil fuel containing iron pyrite into an iron free 9K medium

Description

Desulfurization of fossil fuels using iron and sulfated microorganisms in nonferrous 9Ｋ media {METHOD FOR DESULFURIZATION OF FOSSIL FUELS USING IRON AND SULFUR OXIDISING MICROORGANISM IN IRON FREE 9K MEDIUM}

The present invention relates to a method for desulfurizing fossil fuels, and more particularly, to a method for desulfurizing fossil fuels using iron and sulfated microorganisms in a non-ferrous 9K medium.

Coal is one of the alternative energy sources due to the depletion of petroleum energy. However, a problem caused by using coal as an energy source is air pollution due to the generation of sulfur dioxide (SO ₂ ) during combustion. The main technologies used to remove sulfur are those that are processed during or after combustion, and one of the other pretreatment processes is a biological desulfurization method that removes sulfur without losing fuel of coal.

Sulfur in coal is composed of inorganic sulfur and organic sulfur. Depending on the type of coal, the sulfur content is in the range of about 0.5 to 5% by weight and the content of organic sulfur in the total sulfur is about 20 to 50%. Organic sulfur, which is organically bound in coal, is part of the mother rock and is difficult to remove by biological means. Therefore, research on biological desulfurization so far has focused mainly on the removal of pyrite (FeS ₂ ), which is inorganic sulfur. Generally, the bacteria used to remove sulfur weapons TiO bacillus Faroe oxy Tansu (Thiobacillus ferrooxidans), Bacillus Tio Tio oxy Tansu (Thiobacillus thiooxidans), alcohol Polo Booth knows sword Darius (Sulfolobus acidocaldarius ). These bacteria oxidize insoluble pyrite from coal and remove it in aqueous form in the form of water-soluble iron oxide and sulfate.

Most studies on the removal of sulfur from coal using inorganic trophic eosinophils have been carried out using 9K medium containing 9 g / L of iron, but this method is uneconomical and expensive due to the high cost of sulfur removal from coal. Jarosite (Jarosite) is a disadvantage that is precipitated.

Related prior arts are Korean Patent Laid-Open Publication No. 2011-0064581 (published on June 15, 2011), which includes coal as Gordonia amicalis, Gordonia desulfuricans, and Gordonia. Disclosed is a method for desulfurization by microorganisms such as alkanivorans .

It is an object of the present invention to provide a method for desulfurization of fossil fuels that can secure the economics of microbial treatment.

Desulfurization method of the fossil fuel according to an embodiment of the present invention for achieving the above object comprises the steps of (a) growing a microorganism oxidizing iron and sulfur in iron-based 9K medium; And (b) adding a fossil fuel containing pyrite to a non-ferrous 9K medium to inoculate and remove sulfur by inoculating the grown microbial strain, wherein the ferrous and non-ferrous metals are grown during the microbial growth and leaching of sulfur. It is characterized by supplying carbon dioxide and oxygen to each of the 9K medium.

In the desulfurization method of the fossil fuel according to the present invention, sulfuric acid is added to the 9K medium by removing sulfur from the pyrite fuel containing pyrite using an inorganic nutritional acidophilic microorganism which oxidizes both iron and sulfur in the nonferrous 9K inorganic salt medium. By reducing the cost of ferrous metals, it is possible to improve the economics of microbial processes.

1 is a process flowchart showing a desulfurization method of coal according to an embodiment of the present invention.
2 is a graph showing the redox potential of coal samples according to leaching time.
3 is a graph showing the residual iron concentration in the coal samples with leaching time.
4 is a graph showing sulfate ion concentrations in coal samples according to leaching time.
5 is a graph showing the number of strains in non-ferrous 9K medium containing coal according to leaching time.
6 is a graph showing the pyrite oxidation rate of each coal sample according to the microbial leaching experiment.
7 is a graph showing the sulfur removal rate of the coal sample according to the microbial leaching experiment.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention, and how to accomplish them, will become apparent with reference to the embodiments and drawings described in detail below.

However, it is to be understood that the present invention is not limited to the disclosed embodiments, but may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. It is intended that the disclosure of the present invention be limited only by the terms of the appended claims.

Hereinafter, a method for desulfurizing coal according to an embodiment of the present invention will be described in detail.

1 is a process flowchart showing a desulfurization method of coal according to an embodiment of the present invention.

Referring to Figure 1, the coal desulfurization method according to an embodiment of the present invention shown in the iron-based 9K medium of the growth step of iron and sulfated microorganisms (S110) and non-ferrous 9K medium after the addition of pyrite containing coal Inoculating the microbial strain, leaching, removing the step (S120).

Growth step of the iron and sulfated microorganism (S110) is carried out in the reactor after introducing the iron-based 9K medium, and the iron and sulfated microorganism strain in the reactor.

More specifically, in the growth step (S110) of the iron and sulfated microorganisms, the strain used for the biological desulfurization of coal is an inorganic nutritional eosinophilic microorganism that oxidizes both iron and sulfur, for example Esididithiocillus ferrooxydans ( Acidithiobacillus ferroxidans ; ATCC Nos. 23270) can be used.

These acidicthiobacillus ferroxidans ( oxidithiobacillus ferroxidans ) are fermented iron (Fe ²⁺ ) and reduced inorganic sulfur compounds to oxidize energy to obtain energy, carbon dioxide (CO ₂ ) as an inorganic nutritional bacteria using carbon as a carbon source , Can be grown in iron containing 9K inorganic salt medium at a temperature of 25 ℃ to 35 ℃, pH 1.5 ± 0.5 conditions. At this time, if the culture temperature and pH out of the above conditions, the activity and growth of the strain is insufficient, or iron ions may be precipitated as a salt.

These Acidithiobacillus ferroxidans can be actively grown and survived under low pH conditions using energy free of oxidation of iron and sulfur in the presence of air containing carbon dioxide and oxygen.

The growth of microorganisms was carried out in an iron-based 9K medium with an acid leaching solution supplemented with ferrous sulfate hydrate (FeSO ₄ · 7H ₂ O) and potassium tetrathionate (K ₂ S ₄ O ₆ ) as sources of iron and sulfur, respectively. This can be done in a batch bioreactor. Microorganism growth may be accompanied by agitation of 300 rpm to 400 rpm. If the stirring speed is less than 300 rpm, growth may be insufficient, whereas if it exceeds 400 rpm, a problem arises that hinders the growth of microorganisms and lowers the medium temperature.

The pH of the iron-based 9K medium is preferably adjusted to 1.5 ± 0.5 while adding sulfuric acid (H ₂ SO ₄ ) or calcium hydroxide (Ca (OH) ₂ ) to maintain the optimum growth conditions of the microorganism.

In addition, the iron and sulfated microorganism growth step (S110) may be supplied with air containing a sufficient amount of oxygen (O ₂ ) and carbon dioxide (CO ₂ ) in the iron-based 9K medium through aeration into the air. In this case, the microorganism may use carbon dioxide (CO ₂ ) as a carbon source.

In the microbial inoculation and leaching step (S120), while maintaining the pH of the non-ferrous 9K medium to 1.5 ± 0.5, the addition of coal containing pyrite to the non-ferrous 9K medium inoculated with the microbial strain grown to inoculate pyrite Sulfur is leached and removed through oxidation of the iron and sulfur of the microorganisms.

Non-ferrous 9K medium used in the leaching reactions of the present invention in 3L distilled water _{(NH 4) 2 · SO 4} 9.0g, KCl 0.3g, K 2 HPO 4 1.5g, MgSO 4 · 7H 2 O 1.5g and Ca (NO ₃ ) ₂ · 4H ₂ O 0.03g, considering the margin of _{error, (NH 4) 2 · SO} 4 9.0 ± 2g, KCl 0.3 ± 0.1g, K 2 HPO 4 1.5 ± 0.4g, MgSO 4 · 7H 2 O 1.5 ± 0.4 g and Ca (NO ₃ ) ₂ .4H ₂ O 0.03 ± 0.01 g.

When using a nonferrous 9K medium having such a composition, ferrous sulfate added compared to using a conventional 9K medium ( ferrous sulfate ; FeSO ₄ ) can reduce the cost and improve the economics of the microbial process.

On the other hand, the pH of the non-ferrous 9K medium is preferably adjusted to 1.5 ± 0.5 while adding sulfuric acid (H ₂ SO ₄ ) or calcium hydroxide (Ca (OH) ₂ ).

Since the microbial strain oxidizes pyrite in coal in a batch bioreactor, in the microbial inoculation and leaching step (S120), pyrite is leached from coal containing substantially pyrite to remove sulfur.

The microbial strain then oxidizes the pyrite from coal without affecting organic sulfur in the pyrite containing pyrite in the batch bioreactor.

Anthracite, lignite, bituminous coal, sub-bituminous coal and the like may be used as coal containing pyrite.

In the microbial inoculation and leaching step (S120), Fe ³⁺ ions present in the microbial inoculum are used as an oxidizing agent to oxidize FeS ₂ to release Fe ²⁺ in the leaching solution. ].

_{^{FeS 2 + 6Fe 3 + + 3H}} 2 O → 7Fe 2 + + S 2 O 3 2 - + 6H + ---- [ scheme 1]

Subsequently, Fe ²⁺ ions released from the oxidation of FeS ₂ by Fe ³⁺ ions react with oxygen to be oxidized to Fe ³⁺ ions, and the reaction scheme may be represented by the following [Scheme 2].

Fe ^{2 +} + 1 / 4O ₂ + H ⁺ → Fe ^{3 +} + 1 / 2H ₂ O ---- [Scheme 2]

By microbial inoculum FeS ₂ oxide Fe ^{2 +} ions and released with S ^₂ O _{3 2} ^- ions in the CD thio Bacillus Perot oxy thiooxidans of sulfur by a biological or chemical oxidation potential by the Fe ³⁺ ion mediation SO ₄ ^It is oxidized to ^2- ions, and the reaction scheme can be represented by the following [Scheme 3].

_{^{S 2 O 3 2 - + 8Fe}} 3 + + 5H 2 O → 2SO 4 2 - + 8Fe 2 + + 10H + ---- [ Scheme 3]

Thus, iron and sulfated microorganisms are oxidized to insoluble pyrite from coal containing pyrite and transformed into water-soluble SO ₄ ^{2 −} form to remove sulfur in aqueous solution.

Leaching with iron and sulfated microorganisms is a ferrous sulfate for sulfur removal because Fe ^{2 +} ions are generated during leaching. sulfate ; Since no additional FeSO ₄ ) needs to be added to the process, cost savings can further increase the economics of the bioprocess.

In addition, the microbial inoculation and leaching step (S120) supplies a gas containing a sufficient amount of oxygen (O ₂ ) and carbon dioxide (CO ₂ ), that is, air, which can be supplied through aeration into the air. At this time, the air supplied in the leaching step induces additional oxidation of Fe ²⁺ ions as shown in [Equation 2] to supply carbon dioxide, which is an oxygen and carbon source, so that the amount of pyrite remaining in coal containing pyrite is minimized. .

The present invention will be described in more detail with reference to the following experimental examples. However, the experimental example is for illustrating the present invention and is not limited only to these.

Experimental Example

Microbial Growth Medium Preparation

0.6048 g / L of K ₂ S ₄ O ₆ and 22.4 g / L of FeSO ₄ · 7H ₂ O were added to the 9K medium. The pH of the medium was adjusted to 1.50 with 2M H ₂ SO ₄ . This solution is used only for the growth of microorganisms.

Preparation of Non-Ferrous 9K Medium (Leaching Solution)

As a medium for pyrite leaching, a non-ferrous 9K inorganic salt medium containing no iron was used. Non-ferrous 9K medium was (NH ₄ ) ₂ SO ₄ 9.0g, KCl 0.3g, K ₂ HPO ₄ 1.5g; 1.5 g of MgSO ₄ · 7H ₂ O and 0.03 g of Ca (NO ₃ ) ₂ · 4H ₂ O were prepared in 3 L of water, and the pH of the medium was adjusted to 1.5 using 2M H ₂ SO ₄ .

Strain

As a strain used for microbiological desulfurization of coal, acidithiobacillus ferroxidans (ATCC Nos. 23270) among inorganic trophic acidophilic microorganisms were used.

Strains for microbial leaching experiments were collected from acid mine drainage areas near the Mine Achievement Mine in Korea, and iron-based 9K medium containing 22.4 g / L of FeSO ₄ · 7H ₂ O and 2 mM K ₂ S ₄ O ₆ at pH 1.5 and 35 Grown in shake flasks.

After several passages, a sufficient amount of microorganism was secured and 16s rDNA sequencing was performed. To this end, a total of 10 sets of biomass samples were analyzed with 99% identity and identified as Acidithiobacillus ferroxidans (ATCC Nos. 23270). Ecidithiobacillus ferrooxydans is widely known as a strain that oxidizes both iron and sulfur.

Then, in order to secure the strains required for the microbial leaching experiments, the iron system reinforced with 22.4 g / L FeSO ₄ · 7H ₂ O as the iron source and 0.6048 g / L (2 mM) K ₂ S ₄ O ₆ as the sulfur source in a shake flask Incubation in a 100 ml working volume in 9K medium was transferred to a batch incubator of 1 L working volume. The pH of the batch incubator was maintained at 1.40-1.50 and the redox potential was maintained at 690 mV. Leaching residues and leaching liquors were analyzed by Inductively Coupled Plasma-Atomic Emission Spectrometer (ICP-AES). PH, redox potential, residual iron concentration, residual sulfate ion concentration, and number of microbial strains were monitored for microbial growth, and these results are shown in FIGS. 2 to 7 and Table 3.

The initial redox potential was 380 mV, but reached 690 mV after 5-10 days under this experimental condition. The redox potential of the microbial suspension was maintained at 690 mV for 3 days.

The number of strains of the fully activated microorganism was 2.8 × 10 ⁸ cells / mL in a batch culture reactor.

Coal Sample Preparation

As coal samples, Chinese lignite collected from Neimenggu Meng Tai, lignite collected from Sumatra Lahat, Indonesia and Korean anthracite collected from Hwasun were used. The average particle size of all coal samples was- It was 100 micrometers. The chemical composition and properties of three different coal samples are shown in Table 1 below.

Table 1 Chemical Analysis of Coal Samples

Microbial leaching experiment

Microbial leaching experiments for three different coal samples were run with 1 L of working volume in a glass reactor equipped with a 2.5 L baffle. The condenser was attached to the sealed lid of the bioreactor to minimize water vaporization from the reactor. A hot plate heater was placed at the bottom of the reactor to maintain the internal temperature of the bioreactor at 35 ° C.

The propeller stirrer was fixed at a height of 1.5 cm on the substrate of the reactor driven by a mechanical stirrer at a rotational speed of 320 rpm for homogeneous mixing of the raw materials. The baffles inherent in the walls of the bioreactor help to avoid the formation of vortices. Air containing O ₂ (20.9%) and CO ₂ (0.033%) is blown into the bioreactor at a rate of 1 L / min under the propeller stirrer to maintain 5 mg / L dissolved oxygen (DO) levels in the bioleaching pulp. .

Leaching experiments were carried out in nonferrous 9K inorganic salt medium (Silvermann and Lundgren, 1959) with 10% by weight coal samples and 10% by volume inoculum. The pH and redox potential of the microbial leaching pulp were regularly measured. The pH of the microbial leaching pulp was maintained at 1.5 by adding acid (2M H ₂ SO ₄ ) or base (Ca (OH) ₂ ) as the pH level rose or fell at 1.5. Microbial leaching experiments continued until there was no further change in pH and redox potential. Fe ^{2 +} ion concentration, SO ₄ ^{2 -} a sample of the pulp daily 1.5ml were collected from the bioreactor during the leaching process to the ion concentration and the viable microorganism strain floating be measured.

After the leaching experiment was completed, the microbial leaching pulp was filtered and separated into solid and liquid. To avoid precipitation of metal ions, the solution was washed with a dilute sulfuric acid solution of pH 1.5 instead of ordinary deionized water. The total volume of the leachate containing wash water was measured and used for the calculation of the elemental composition in the leach liquor, the results are shown in Table 2. The washed leach residue was dried in a hot air oven at 50 ° C. until no weight change was observed and then the dried leach residue was ground with a mortar.

2 is a graph showing the redox potential of coal samples according to leaching time.

As shown in Figure 2, microbial leaching experiments using Chinese lignite, Indonesian lignite and Korean anthracite can be seen that both have a 2-3 days of incubation period and 20 days after the incubation period and subsequent stop phase. In addition, it can be seen that the redox potential decreases with time during the incubation period.

This reduction in redox potential is due to the change in the Fe ³⁺ / Fe ²⁺ ratio in solution. Fe ³⁺ ions oxidize FeS ₂ to release Fe ²⁺ in solution, reducing the Fe ³⁺ / Fe ²⁺ ratio, resulting in a reduction in redox potential at experiments 0-3 (see Scheme 1).

^{_{FeS 2 + 6Fe 3 + + 3H}} 2 O → 7Fe 2 + + S 2 O 3 2 - + 6H + ---- [ scheme 1]

After 3 days after the coal, regardless of the result of the type of observing the oxidation-reduction potential change was confirmed that the oxidation-reduction potential increases, which is due to Fe ^{+ 2} ion is oxidized to Fe ^{+ 3} [see scheme 2].

Fe ^{2 +} + 1 / 4O ₂ + H ⁺ → Fe ^{3 +} + 1 / 2H ₂ O ---- [Scheme 2]

In addition to Fe ^{3 +} ions because of the chain of cyclic process oxidizes FeS _2, FeS ₂ is also of a Fe ^{2 +} S ₂ O ₃ solution with ion oxide ^2- emit ions [see Scheme 1]. S ₂ O ₃ ^2- is oxidized to SO ₄ ^2- ions by biological or chemical Fe ³⁺ ion mediation by the sulfur oxidation potential of Esididithiocillus ferrooxydans (see Scheme 3).

_{^{S 2 O 3 2 - + 8Fe}} 3 + + 5H 2 O → 2SO 4 2 - + 8Fe 2 + + 10H + ---- [ Scheme 3]

FeS ₂ oxidation with sulfur oxidation is an acid production process, while oxidation of Fe ²⁺ ions is an acid consumption process. Part of the acid required for Fe ²⁺ oxidation was supplied by the acid produced by FeS ₂ , but when the pH was 1.5 or more, 2M H ₂ SO ₄ was added to adjust the pH. When the pH was less than 1.45, a small amount of calcium hydroxide (Ca (OH) ₂ ) was added to the microbial leaching pulp and adjusted to 1.5. The amount of H ₂ SO ₄ / Ca (OH) ₂ required to adjust the pH of 1 ton of coal to 1.5 was calculated [see Table 2].

[Table 2] Summary of microbial leaching test results

As shown in Table 2, the acid requirements for Chinese lignite and Korean anthracite were 70 kg / ton and 75 kg / ton, respectively, while Indonesia lignite consumed 94 kg / ton. In the case of Korean anthracite coal, the required amount of Ca (OH) ₂ was negligibly small at 2 kg / ton, and the Ca (OH) ₂ demand in lignite in Indonesia and China was 10 kg / ton and 20, respectively. It was very high at kg / ton. For all coal samples, the amount of clean coal (coal) generated after the desulfurization reaction of microorganisms was 906 kg / ton, 856 kg / ton, 896 kg / ton in China lignite, Indonesia lignite and Korea anthracite, respectively, 9% per ton coal, Mass loss of 14% and 10% occurs.

3 is a graph showing the residual iron concentration in the coal samples with leaching time.

As shown in FIG. 3, iron and iron concentrations of lignite in China and Indonesia show a similar tendency, whereas Korean anthracite has a high residual Fe ²⁺ concentration and a relatively fast iron oxidation rate. The reason why the redox potential is high in the above-described Korean anthracite coal experiment of FIG. 2 is that the concentration of iron separated from the anthracite coal of Korea is higher than that of Indonesia and China lignite.

As shown in FIG. 3, the concentration of Fe ²⁺ ions was the highest on the third day of the experiment regardless of the type of coal. The Fe release from Korea anthracite ²⁺ ion concentration is higher than in Experiment 3, the primary 0.86g / L with the Fe ²⁺ concentration of Indonesian and Chinese brown coal 0.62g / L, 0.53g / L. Fe ²⁺ ions are oxidized to Fe ³⁺ ions by esididithiocillus ferrooxydans after 3 days, and decrease with time. The oxidation rate of iron calculated in FIG. 3 is relatively high in 0.0052 g Fe ²⁺ / L / h in Korean anthracite coal and relatively low in 0.0022 and 0.0016 g Fe ²⁺ / L / h in Indonesia and China lignite, respectively. The difference in iron oxidation rate according to the type of coal is affected by the microbial activity and the physical properties of the coal itself.

4 is a graph showing sulfate ion concentrations in coal samples according to leaching time.

Referring to FIG. 4, sulfur oxidation from S ₂ O ₃ ^2- ions to SO ₄ ^2- ions by Fe ³⁺ mediated chemical oxidation or Escidithiobacillus ferrooxydans tends to increase with reaction time. have.

As described above, Ca (OH) ₂ added for pH adjustment can be precipitated as gypsum (CaSO ₄ ) in combination with SO ₄ ^{2 −} ions. The maximum SO ₄ ^{2 -} ion concentrations of leached pulp during the microbial oxidation process were 16.2, 15.7 and 18.6 g / L in Chinese lignite, Indonesian lignite and Korean anthracite, respectively. Sulfuric acid added to adjust the pH to 1.5 greatly influences the total SO ₄ ^2- ion concentration, and SO ₄ ^2- ions formed due to pyrite oxidation also affect.

5 is a graph showing the number of strains in non-ferrous 9K medium containing coal according to leaching time.

Referring to FIG. 5, since the third leaching experiment, the number of strains of 10 ⁸ cells / mL or more was maintained regardless of coal samples, indicating stable activity. In particular, about twice as many microbial strains were observed in China compared to the number of strains in non-ferrous 9K medium containing Indonesia and domestic coal.

An important fact that can be seen in the above experimental example is that a good level of microbial strains is maintained during the leaching experiment so that the microbial leaching reaction takes place actively.

Based on the total amount of Fe and S contained in the leaching residue and solution, the pyrite oxidation rate was calculated in consideration of the amount of Fe added during the experiment.

iron pyrites Oxidation rate  And sulfur removal rate methods

Pyrite oxidation was calculated based on the analysis of the feed and leaching residue according to the following [Equation 1].

[Equation 1]

(Where Fe (r) is the iron content in the leach residue and Fe (f) is the iron content in the feed including the iron content isolated from the coal sample.)

In addition, the sulfur removal rate (%) was calculated according to the following [Equation 2].

&Quot; (2) "

(Where S (r) is the total sulfur content in the residue and S (f) is the total sulfur content in the feed that combines the H ₂ SO ₄ additive and the sulfur content separated from the coal feedstock).

[Table 3] Chemical analysis of microbial leaching residue and leaching solution

6 is a graph showing the pyrite oxidation rate of each coal sample according to the microbial leaching experiment.

As shown in FIG. 6, pyrite oxidation of Korean anthracite coal was 79.4%, while Indonesia and China lignite were 37.3% and 44.2%, respectively.

However, the reason for the relatively low pyrite oxidation in Indonesia and China lignite is presumably due to insufficient separation of pyrite minerals from Indonesia and China lignite. The bulk separation of pyrite minerals largely depends on the crushability of the coal and the crushability of the coal is determined from their Hardgrove Grindability Index (HGI). The HGI index of Korea's anthracite coal is 106.5, and Chinese and Indonesian lignite are 48.4 and 63.9, respectively.

It can be predicted that coals with low values of the HGI index are more difficult to grind, and higher values are more easily comminuted and consequently the simpler separation of pyrite minerals from lignite compared to anthracite. However, pyrite oxidation in Korean anthracite seems to be particularly promising when operating batch processes, and pyrite oxidation is further improved when operating on two to three stages of continuous microbial oxidation processes normally performed at full scale operation. Can be.

7 is a graph showing the sulfur removal rate of the coal sample according to the microbial leaching experiment.

As shown in FIG. 7, pyrite removal from Chinese lignite, Indonesia lignite and Korean anthracite was found to be 92%, 96% and 98%, respectively.

In summary, pyrite removal is as high as 90% or higher regardless of coal samples. Sulfur removal was highest in anthracite in Korea, followed by lignite in Indonesia and China. The pyrite removal rate shows high efficiency even in a batch microbial leaching system as in the present embodiment, and further improved desulfurization efficiency can be expected when the two to three step continuous microbial oxidation process is performed.

On the other hand, in the embodiment of the present invention described for the convenience of the description of the coal containing pyrite, but not limited to only the material containing pyrite, but partially refined or roughly refined solid, wood-derived feedstock and It can also be used for fossil fuels such as kneaded solids.

Although the embodiments and experimental examples of the present invention have been described above with reference to the accompanying drawings, the present invention is not limited to the above examples and experimental examples, but may be modified in various forms, and in the technical field to which the present invention pertains. Those skilled in the art will understand that the present invention can be implemented in other specific forms without changing the technical spirit or essential features of the present invention. Therefore, it is to be understood that the embodiments and the experimental examples described above are exemplary in all respects and not restrictive.

Claims (12)

(a) growing a microbial strain that oxidizes both iron and sulfur in an iron-based 9K medium; And
(b) inoculating and removing sulfur by inoculating the microbial strain grown on the iron-based 9K medium after adding fossil fuel containing pyrite to the non-ferrous 9K medium;
The desulfurization method of the fossil fuel, characterized in that the supply of carbon dioxide and oxygen to each of the iron-based and non-ferrous 9K medium during the growth of the microbial strain and leaching reaction of the microbial strain and sulfur.
The method of claim 1,
The non-ferrous 9K medium is
In 3L distilled water _{(NH 4) 2 · SO 4} 9.0 ± 2g, KCl 0.3 ± 0.1g, K 2 HPO 4 1.5 ± 0.4g, MgSO 4 · 7H 2 O 1.5 ± 0.4g and _{Ca (NO 3) 2 · 4H} 2 A method for desulfurizing fossil fuels, having a composition in which O is dissolved in 0.03 ± 0.01 g.
The method of claim 1,
The microorganism is
A method for desulfurizing fossil fuels, characterized in that it is Acidithiobacillus ferroxidans (ATCC Nos. 23270).
The method of claim 3,
The step (b)
Desulfurization method of fossil fuel, characterized in that carried out under pH 1.5 ± 0.5 conditions.
5. The method of claim 4,
PH of the non-ferrous 9K medium is
Sulfuric acid (H ₂ SO ₄ ) or calcium hydroxide (Ca (OH) ₂ ) is added to the non-ferrous 9K medium is controlled by the desulfurization of the fossil fuel.
The method of claim 3,
The step (a)
Desulfurization method of fossil fuel, characterized in that carried out under pH 1.5 ± 0.5 conditions.
The method according to claim 6,
PH of the iron-based 9K medium is
Sulfuric acid (H ₂ SO ₄ ) or calcium hydroxide (Ca (OH) ₂ ) is added to the iron-based 9K medium to control the desulfurization of the fossil fuel.
The method of claim 3,
The step (a)
Desulfurization method of fossil fuel, characterized in that carried out at a temperature of 25 ℃ to 35 ℃.
The method of claim 1,
The step (a)
Introducing an iron-based 9K medium and a microbial strain oxidizing iron and sulfur into the reactor,
The desulfurization method of the fossil fuel comprising the step of growing the microbial strain in the iron-based 9K medium introduced into the reactor.
The method of claim 1,
The iron-based 9K medium
A method for desulfurizing fossil fuels, further comprising ferrous sulfate hydrate (FeSO ₄ .7H ₂ O) and potassium tetrathionate (K ₂ S ₄ O ₆ ) as sources of iron and sulfur, respectively.
The method of claim 1,
The fossil fuel is
A method for desulfurizing fossil fuels, which is pyrite-containing coal.
The method of claim 1,
The carbon dioxide and oxygen
A method for desulfurizing fossil fuels, which is supplied through aeration into the air.

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