JP3506394B2 - Method and apparatus for desulfurizing clay using sulfur-oxidizing bacteria - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention utilizes bacteria capable of oxidizing sulfur and iron to remove sulfur and iron contained in clay by a batch or continuous desulfurization method to produce various ceramic materials including ceramics. In particular, the present invention relates to a method and an apparatus for appropriately producing good quality clay.

[0002]

2. Description of the Related Art Generally, the quality of ceramic materials is greatly influenced by the composition of the raw clay, so that clay with few impurities must be used in order to produce high quality ceramic materials. I won't.
Typical of such impurities is pyrite (FeS ₂ )
Is. For example, if ceramics are manufactured using clay containing pyrite, when baking the ceramics, a large amount of sulfurous acid gas is generated, which damages the kiln and induces air pollution, which causes the ceramics itself to turn red and generate pores. The commercial value is lost.
The main cause of reddening is sulfur and iron components contained in clay. Therefore, in order to produce good quality ceramics, good quality clay (desulfurization clay) without pyrite is required. Therefore, it is an object of the present invention to effectively present pyrite contained in clay. The present invention also aims at presenting a device for implementing the above method.

[0003]

According to the present invention for solving the above-mentioned problems, the pH is adjusted by using sulfuric acid after slurrying.
Against the clay slurry was adjusted to a range of 1.5 to 2.5,
And inoculating the concentrated separated <br/> sulfur oxides bacteria from cultured in the seed medium culture with enhanced activity, residence time of which 5 to 10 days, in the clay slurry with stirring under air injection pyrite was eluted by biological oxidation, washing the biological oxidation treated clay is mainly characterized in that to obtain a desulfurized clay.

In addition to the above characteristics, the use of 0.1N HCl for washing biologically oxidized clay,
The air injection rate is 1 vvm (1 times the liquid volume per minute), and the concentration of the clay slurry is 40% (w / v) or higher, the carbon dioxide in the supplied air is 5%.
Secondary injection of carbon dioxide to satisfy (v / v) and addition of nutrients required for growth of sulfur-oxidizing bacteria to biologically oxidized clay slurry are secondary It has a feature.

[0005] Further according to the present invention is an apparatus for obtaining a pyrite removal and desulfurization clay contained in the clay, (1) viscosity <br/> soil slurry clay were mixed and stirred with water, slurried and maker, and sieve to remove (2) mass of pyrite and other impurities of the clay slurry maker clay slurry made of a clay slurry having passed through the (3) the sieve, using sulfuric acid pH was adjusted to a range of 1.5 to 2.5, a certain amount of concentrated sulfur oxide bacteria was inoculated was stirred under air injection, pyrite biologically multistage to oxidize and remove A desulfurization bioreactor , (4) a reaction solution / clay separation tank for separating clay and wastewater from the oxidized clay slurry , and (5) a clay separated from the reaction solution / clay separation tank. Wash, with sulfuric acid adhering to the surface of the clay Clay cleaner for removing iron , (6) Filter for filtering washed clay , (7) Injection of calcium hydroxide, reaction liquid / clay separation tank (4) and filter (6) ) wastewater treatment tank for removing the separated sulfuric acid and iron from the washing waste water from and is composed of a limestone separation tank for separating a mixture with limestone from the water which has passed through the (8) the waste water treatment tank, The water that has passed through the limestone separation tank (8) is a clay slurry manufacturing device (1).
It is characterized by utilizing sulfur-oxidizing bacteria, which is characterized in that it can be supplied to and reused in the production of clay slurry.

[0006]

According to the method for desulfurizing clay according to the present invention, a sulfur-oxidizing bacterium that oxidizes reduced forms of sulfur and iron compounds and obtains energy required for growth and proliferation of bacterial cells from the oxidation reaction is used. As a result, pyrite in the solid state contained in the clay is eluted and removed by the oxidizing action, and high-quality clay can be produced.

This will be described in detail. Sulfuric acid at a pH of 1.5 to
A highly activated sulfur-oxidizing bacterium, which had been concentrated and separated by culturing in a clay slurry containing an inoculation medium adjusted to a range of 2.5, was inoculated into a pyrite-containing clay, which was retained for 5 to 10 days,
The pyrite in the clay slurry is eluted by biological oxidation with stirring under the injection of air. The biologically oxidized clay is washed to obtain desulfurized clay.

In this method, the oxidation reaction of pyrite by sulfur-oxidizing bacteria is most active when the pH of the clay slurry is adjusted to 1.5 to 2.5 with sulfuric acid. Although the residence time of the biological oxidation reaction of the clay slurry varies depending on the concentration of the clay slurry, about 5 days to 10 days is suitable, and the aeration rate of air is 1 vvm (1 volume of liquid per minute is 1 vvm).
Double the air permeability). Clay slurry concentration is 40% (w /
v) In the above cases, in order to enhance the activity of bacteria,
It is more appropriate to inject carbon dioxide from the outside in order to adjust the carbon dioxide concentration in the supplied air to 5% (v / v). While many types of slurry reactors are possible for the biological oxidation reaction of clay, a multi-stage slurry bioreactor is suitable because clay residence time in the reactor must be long. When using a multi-stage reactor, the newly injected clay is the first reactor and is inoculated by mixing with clay particles in the reactor where bacteria are already attached.
Further, it is preferable to add a small amount of nutrient salt in order to supply the nutrients necessary for the growth of the bacterial cells. The addition may be at the time of slurry production or inoculation of sulfur-oxidizing bacteria. Particularly in the case of the batch system, it is more appropriate to add the nutrient salt during the production of the slurry, and in the case of the continuous system, the method of directly adding the nutrient salt to the reactor is more suitable.

It is appropriate to use 0.1N- HCl for cleaning the biologically oxidized clay, and the cleaning can easily remove sulfur and iron adhering to the surface of the clay.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The desulfurization apparatus of the present invention having such a structure will be described in more detail with reference to the drawings. The apparatus shown in FIG. 1 is a stirrer type clay slurry manufacturing device 1, a sieve 2, a bioreactor 3, a reaction liquid / clay separation tank 4, a clay washing device 5, a filter device 6,
It is composed of a wastewater treatment tank 7 and a limestone separation tank 8. According to this continuous desulfurization equipment for clay, clay is produced in clay slurry, removal process of lumpy pyrite in clay slurry, biological process of biological removal of pyrite using sulfur-oxidizing bacteria, and separation process of clay and reaction liquid. Desulfurization is carried out through a washing process of clay and a wastewater treatment process.

More specifically, clay is continuously slurried by mixing it with water in a clay slurry maker 1, and after removing the mass of pyrite and other impurities by a sluice, the clay is mixed with the nutrient salts of bacteria to form a living organism. Injected into the reactor 3. After inoculating a certain amount of concentrated sulfur-oxidizing bacteria, the pyrite remaining in the clay slurry was removed by the oxidizing action of the bacteria while being stirred under air injection, and the pyrite was removed in the bioreactor. The slurry is separated into clay and waste water in the reaction liquid / clay separation tank 4. The clay separated in the reaction solution / clay separation tank is washed with dilute hydrochloric acid (0.1N- HCl ) in the clay cleaner 5 to remove the sulfur and iron adhering to the surface of the clay, and then passed through the filter 6. Becomes desulfurized clay. The biological reaction wastewater separated in the reaction liquid / clay separation tank and the cleaning wastewater separated in the filter are treated with calcium hydroxide in the wastewater treatment tank 7 to remove sulfur and iron in the wastewater, and a limestone separation tank After the limestone is separated from the limestone, the limestone is supplied to the clay slurry producing device 1 and reused for producing the slurry.

Although many kinds of slurry reactors are possible in the bioreactor 3, a multistage slurry bioreactor is used because the residence time of clay in the reactor must be long in the case of clay microbiological desulfurization. Is suitable and the pH of the slurry is adjusted to 1.5-2.5 using sulfuric acid in a bioreactor to give an aeration rate of 1 vvm. With a high concentration clay slurry of 40% (w / v) or more, carbon dioxide in the air supplied to enhance the activity of bacteria is 5% (v / v).
It is preferable to inject carbon dioxide in order to achieve v). Since most of the sulfur-oxidizing bacteria are attached to the clay particles, the newly injected clay is inoculated in the first reactor of the multi-stage reactor by mixing with the existing clay particles to which the bacteria are attached.

Next, an example of this study will be described. Example 1 Cell culture and concentrated sulfur-oxidizing bacteria (Thiobacillus fe
rrooxidans) in a growth medium ((NH ₄ ) ₂ SO ₄
3.0, K ₂ HPO ₄ 0.5, KCI 0.1, MgSO ₄
・ 7H ₂ O 0.5, Ca (NO ₃ ) ₂ 0.01, FeSO ₄
After culturing with 7H ₂ O 45 g / 1, pH 2.5) for 76 hours, the cells were concentrated by centrifugation. The concentrated cells were cultured in a pyrite medium for 14 days for further activation. The activated cells were centrifuged to separate pyrite and the culture solution. The cells thus obtained were used for desulfurization of clay.

Desulfurization of clay by a batch process using sulfur-oxidizing bacteria and salt ((NH ₄ ) ₂ SO ₄ 3.
_{0, K 2 HPO 4 0.5,} KCI0.1, MgSO 4 · 7
H ₂ O 0.5, Ca (NO ₃ ) ₂ 0.01 g / 1) was mixed with water, and the activated bacterial cells obtained above were inoculated into a clay slurry to give a biological reaction of 500 mg / liter. The desulfurization reaction was performed in a vessel. At that time, the inoculum of bacterial cells was 10 ⁹ cells
/ Ml, clay concentration is 30% (30 per liter of water
0 g of clay) and the pH was adjusted to 2.0 with sulfuric acid. As a result of the experiment, 90% or more of the pyrite contained in the initial clay was removed in 7 days. The removal rate of pyrite at that time was 1.714 mg FeS ₂ ^{−1 −1} · d ⁻¹ (1 day, 1,714 mg FeS ₂ per liter of reaction solution).

Example 2 An experiment was conducted under the same conditions as in Example 1 except that the concentration of clay was 60% (600 g of clay per liter of water) and the other conditions were the same as in Example 1. As a result, 90% of pyrite in the initial clay was removed in 12 days, and the maximum desulfurization rate at that time was 1.
It was 485 mg / FeS ₂ ^{−1 −1} · d ⁻¹ .

Example 3 Desulfurization of clay by a continuous process using sulfur-oxidizing bacteria The clay was continuously subjected to biodesulfurization treatment using the apparatus shown in FIG. The inoculated cells were the activated sulfur-oxidizing bacteria prepared according to Example 1, the clay concentration was 30% in the multi-stage slurry bioreactor, and the reaction residence time of the clay slurry was 5 days. The pH was adjusted to 1.5 to 2.5 with sulfuric acid, and the aeration amount was 1 vvm.
As a result, 95% of the pyrite contained in the clay was removed.

[0017]

According to the desulfurization method and the continuous desulfurization apparatus as described above, most of the pyrite can be removed, and the activity of the fungus body is not lowered even if it is continuously operated for several months or more, and it is as high as 90 to 98%. Desulfurization efficiency is maintained and good quality clay can be produced.

[Brief description of drawings]

FIG. 1 is a schematic view of a continuous desulfurization apparatus for clay by microbial desulfurization.

[Explanation of symbols]

1 Clay slurry maker 2 Fluui 3 Multi-stage desulfurization bioreactor 4 Reaction liquid / clay separation tank 5 clay washer 6 filter 7 Wastewater treatment tank 8 Limestone separation tank

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor, Zhao, Shu, 595-13, Mizusawa-dong, Guri-si, Gyeonggi-do, Republic of Korea (72) Inventor, Tadahiro Mori, 5-9-1, Kohokudai, Abiko-shi, Chiba (56) References Flat 4-254462 (JP, A) JP-A 5-254975 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C04B 33/10 C04B 33/04 C04B 33/02 C04B 35 / 00-35/22 B28C 1/00-9/04 C12S 13/00 C02F 11/00-11/20

Claims (6)

(57) [Claims] 1. The pH is adjusted with sulfuric acid after slurrying.
Against the clay slurry was adjusted to a range of 1.5 to 2.5,
And inoculating the concentrated separated <br/> sulfur oxides bacteria from cultured in the seed medium culture with enhanced activity, residence time of which 5 to 10 days, in the clay slurry with stirring under air injection pyrite was eluted by biological oxidation, washing the biological oxidation treated clays, desulfurization process of the clay using sulfur-oxidizing bacteria, characterized in that to obtain a desulfurized clay. 2. The method for desulfurizing a clay using sulfur-oxidizing bacteria according to claim 1, wherein 0.1N- HCl is used for washing the biologically oxidized clay. 3. The air injection according to claim 1, wherein the air injection is 1 vvm.
A method for desulfurizing clay using sulfur-oxidizing bacteria, which has an aeration rate of (1 times the liquid volume per minute). 4. The carbon dioxide according to claim 1, wherein carbon dioxide is separately supplied from the outside so that carbon dioxide in the supplied air satisfies 5% (v / v) when the concentration of the clay slurry is 40% (w / v) or more. A method for desulfurizing clay using sulfur-oxidizing bacteria, characterized by injecting. 5. The method for desulfurizing clay using sulfur bacteria according to claim 1, wherein nutrient salts necessary for the growth of sulfur-oxidizing bacteria are added to the clay slurry subjected to biological oxidation treatment. 6. A device for obtaining the pyrite removal and desulfurization clay contained in the clay, and (1) clay were mixed and stirred with water, viscosity <br/> soil slurry maker a slurry, ( 2) a sieve to remove lumps of pyrite and other impurities of the clay slurry maker clay slurry made of a clay slurry having passed through the (3) the sieve, the pH with sulfuric acid 1.5 adjusted to the range of 2.5, a certain amount of inoculated with concentrated sulfur oxide bacteria was stirred at injection of air, and multi-stage desulfurization bioreactor for biological oxidation removal of pyrite , (4) from the acid-treated clay slurry, wash the reaction solution / clay separation vessel for separating the clay and the waste water, the clay is separated from (5) the reaction solution / clay separation tank, the surface of the clay Viscosity for removing sulfuric acid and iron adhering to And washer (6) and filter for filtering the washed clay, (7) calcium hydroxide was injected, the reaction solution / clay separation tank (4) and washing waste liquid separated from the filter (6) wastewater treatment tank for removing sulfuric acid and iron from and, (8) from the water which has passed through the waste water treatment tank limestone separation tank for separating limestone and mixtures are composed, limestone separation tank (8) The clay desulfurization apparatus using sulfur-oxidizing bacteria, wherein the water that has passed through is supplied to a clay slurry manufacturing device (1) and can be reused in the clay slurry manufacturing.