KR20190023459A - Preparation of adsorbent for removal of sulfur compounds using acid mine drainage - Google Patents

Abstract

The present invention relates to a method for manufacturing an adsorbent capable of removing sulfur compounds with high efficiency using acid mine drainage. According to the present invention, the method comprises: a step of generating a mixed sludge of inorganic binder-hydrated iron which can precipitate the mixed sludge of inorganic binder-hydrated iron having a three-dimensional network structure by putting sodium hydroxide (NaOH) or calcium hydroxide (Ca(OH)_2) and an inorganic binder to acid mine drainage and stirring the same; a sludge dehydrating step of dehydrating the mixed sludge of precipitated inorganic binder-hydrated iron; and an absorbent molding step of extrusion-molding the dehydrated inorganic binder-hydrated iron mixture into pellets and drying the same to mold thereof as the absorbent.

Description

[0001] The present invention relates to an adsorbent for removing sulfur compounds from acid mine drainage,

The present invention relates to a method for producing an adsorbent capable of removing sulfur compounds with high efficiency using acid mine drainage.

Acid mine drainage (AMD) is a pollutant that causes continuous pollution of water quality and soil in mine or mine. Many methods for treating such acidic mine drainage have been researched and developed.

Acid mine drainage is formed by oxidation of sulfide minerals such as pyrite (FeS ₂ ) and white iron (FeS) exposed to the atmosphere by reacting with oxygen and water, and it is acidic due to its low pH, and iron, aluminum, manganese And the like.

The treatment methods of acid mine drainage are divided into active treatment and passive treatment. Aggressive treatment methods are methods using pH control, ion exchange and adsorption, coagulation, and filtration using a neutralizing agent. Typical active treatment methods include reverse osmosis, ion exchange, and electrodialysis. The passive treatment method is a method in which power is not administered by using organic materials and limestone, and typical passive treatment methods include successive alkalinity-producing systems (SAPS).

However, in the method of treating acidic mine drainage, the metals contained in the acidic mine drainage are discharged after sedimentation with sludge, and the sludge is treated as waste, so that the waste treatment cost has to be further increased.

Accordingly, the present inventors have developed a technology capable of reducing the amount of sludge discharged while purifying acidic mine drainage by preparing an adsorbent which can be industrially used by using acid mine drainage.

The object of the present invention is to provide a method for producing an adsorbent capable of removing sulfur compounds with high efficiency by using acid mine drainage.

The method for producing an adsorbent for removing sulfur compounds using acidic mine drainage according to the present invention comprises the steps of adding sodium hydroxide (NaOH) or calcium hydroxide (Ca (OH) ₂ ) and inorganic binder to an acidic mine drainage, A mixed sludge-producing step of an inorganic binder-iron hydroxide precipitating a mixed sludge of an inorganic binder-iron hydroxide; A sludge dewatering step of dewatering the mixed sludge of the precipitated inorganic binder-iron hydroxide; And an adsorbent forming step of extruding and sintering the mixed sludge of the inorganic binder-iron hydroxide dehydrated through the sludge dewatering process into a pellet, and drying the same to form an adsorbent.

Preferably, the process for producing an inorganic binder-iron hydroxide mixed sludge is characterized by adding caustic soda (NaOH) or liquid calcium hydroxide (Ca (OH) ₂ ) so that the acid mine drainage is maintained at a pH of 8 to 9.5.

Preferably, the inorganic binder is at least one selected from silica sol, bentonite, clay, mica, kaolin, montmorillonite, and modified silicate.

Preferably, the inorganic binder is mixed 0.1 to 0.5 wt.% (G) based on 13 L of acid mine drainage.

Preferably, the mixed binder-iron hydroxide mixed sludge production process is characterized in that the coagulant is further added at 5-10 ppm so that precipitation of the iron hydroxide rapidly proceeds.

Preferably, the adsorbent molding process is characterized in that after extrusion molding, it is dried at a temperature of 100 ° C to 120 ° C for 3-6 hours.

The adsorbent produced by using the acidic mine drainage of the present invention has an excellent adsorption rate of sulfur compounds including hydrogen sulfide and is effective for recycling acidic mine drainage treated with drainage as an industrial adsorbent.

In addition, there is an advantage in that an adsorbent having a high hydrogen sulfide adsorbing ability can be produced while using NaOH or a cost-effective Ca (OH) ₂ .

1 is a process diagram of a method for producing an adsorbent for removing sulfur compounds using acid mine drainage according to the present invention.
2 is a graph of adsorption capacity (breakthrough curve) of hydrogen sulfide discharged from an adsorption tower using an adsorbent according to the present invention.

Hereinafter, the present invention will be described in detail.

The method for producing an adsorbent for removing sulfur compounds using acidic mine drainage according to the present invention comprises a step of storing an acidic mine drainage (S10), a step (S20) of producing an inorganic binder-iron hydroxide mixed sludge, a sludge dewatering step (S30) (S40).

The acidic mine drainage storage process (S10) receives and stores acidic mine drainage using a storage tank. In the reservoir, solid foreign matter contained in the acid mine drainage is separated and settled.

Inorganic binder-mixed sludge formation step (S20) of the iron hydroxide is received by a sludge tank supplying the acid mine drainage are stored in the storage bath of caustic soda (NaOH) or liquid calcium hydroxide (Ca (OH) ₂₎ and stirred added, the inorganic binder To produce a mixed sludge of inorganic binder-iron hydroxide.

NaOH or Ca (OH) ₂ precipitates iron hydroxide such as FeO (OH), Fe ₂ O ₃ , Fe (OH) ₃ and the like, which are present in acid mine drainage. At this time, NaOH or Ca (OH) ₂ is preferably added so that the pH of the sludge reaction tank is maintained at 8 to 9.5. If the pH is less than 8, unreacted iron compounds may exist in the acid mine drainage, and if the pH is more than 9.5, there is a problem that a large amount of chemicals are required to neutralize the effluent discharged from the sludge reactor.

On the other hand, a flocculant for changing the surface charge of the iron hydroxide fine particles may be added so that the initially coagulated iron hydroxide rapidly coagulates and precipitates easily. Such flocculant is preferably a 2-propenoic acid sodium 2-propenamide polymer (SODIUM 2-PROPENOATE 2-PROPENAMIDE POLYMER), and the flocculant is added at 5-10 ppm. If it is less than 5 ppm, the precipitation time of the iron hydroxide becomes long. If it exceeds 10 ppm, the iron hydroxide can be precipitated quickly, but the adsorption rate of the sulfur compound is low and the economical cost due to the use of the expensive coagulant is increased.

In addition, the inorganic binder reacts with precipitated iron hydroxide to form a three-dimensional network structure, and forms a mixed sludge of an inorganic binder-iron hydroxide having a high specific surface area. The inorganic binder is preferably an inorganic binder containing Si- or Al-. In particular, at least one selected from silica sol, bentonite, clay, mica, kaolin, montmorillonite, and modified silicate is used. The inorganic binder may be used in an amount of 0.1 to 0.5 wt.% (G) based on 13 L of acid mine drainage. At this time, if the content of the inorganic binder is less than 0.1 weight (g), there may be a problem that the three-dimensional network structure of the resulting inorganic binder-iron hydroxide mixed sludge is difficult to maintain, and it is difficult to maintain a constant shape after molding. If the amount is more than 0.5 weight (g), there is a problem that the content of the inorganic binder in the mixed sludge of the inorganic binder-iron hydroxide is unnecessarily high.

In the sludge dewatering process (S30), the dewatering device dehydrates the mixed sludge of the inorganic binder-iron hydroxide precipitated in the sludge reaction tank to have a water content of 70-80%. At this time, it is preferable to use a filter press as the dewatering device. At this time, when the water content of the mixed sludge of the inorganic binder-iron hydroxide exceeds 80%, there is a problem that it is difficult to form pellets with a high water content.

In the adsorbent forming step (S40), the mixed sludge of the inorganic binder-iron hydroxide dehydrated through the sludge dewatering process is extruded into a pellet-shaped adsorbent into a molding die of a predetermined shape, and the mixture is extruded at a temperature of 100 ° C to 120 ° C for 3-6 hours Dry. At this time, there is a problem that the strength of the pellets is lowered at a temperature lower than 100 ° C, and there is a problem that the pellets may be cracked when the temperature is higher than 120 ° C.

The adsorbent prepared from acidic mine drainage through such a process can be used as an adsorbent having a high hydrogen sulfide adsorbing ability.

<Experimental Example>

About 13 L of acidic mine drainage discharged from Yeongdong coal mine was added NaOH-containing components as shown in Table 1, and maintained at pH 9 (about 8.69 g) for 1 hour to precipitate a mixed sludge of inorganic binder-iron hydroxide . Thereafter, the mixed sludge of the inorganic binder-iron hydroxide was dewatered to a water content of 80% or less with a filter press. The mixed sludge of dehydrated mineral binder and iron hydroxide was extruded into pellets and dried at 110 ° C for 5 hours to prepare each adsorbent. In addition, as a comparative example, Ca (OH) ₂ was added to the acidic mine drainage without adding an inorganic binder, and the resulting sludge was maintained at about pH 9 for 1 hour.

ingredient Content (g)
Example 1 NaOH (20%) 8.69 g Inorganic binder (silica sol) 0.4 g

Example 2 NaOH 8.65 g Inorganic binder (silica sol) 0.41 g Coagulant (2-propenoate sodium 2-propenamide polymer) 0.15 g Comparative Example Ca (OH) ₂ (33%) 24.5 g

2.141 g of the adsorbent of Examples 1 and 2 and the comparative example were placed in a dry adsorption tower and a gas containing hydrogen sulfide was passed under the same conditions as in Table 2 to confirm whether or not hydrogen sulfide was contained in the gas discharged from the adsorption tower. Respectively. The adsorption amount of hydrogen sulfide adsorbed on the adsorbent was analyzed and shown in Table 3, and the adsorption capacity was confirmed.

Item Item The bed volume (Bed Volunw, l) 3.88 ㅧ 10 ^-3 H ₂ S concentration (ppm) 10,300 Flow rate (cc / min) 80 Space Velocity (hr ^-1 ) 1,230 Space Velocity, sec 2.93 Break through point 5%

As can be seen from the graph of FIG. 2, the hydrogen sulfide contained in the gas flowing into the adsorption tower was found to adsorb almost all of the hydrogen sulfide until the adsorption time of about 250 to 350 minutes elapsed, and the removal rate of hydrogen sulfide (H ₂ S) was 99.9% or more .

In addition, as shown in Table 3, it was confirmed that the adsorption performance of hydrogen sulfide adsorbed on the adsorbent had an excellent adsorption performance of 20.5 and 23.9 weight ratio by weight.

absorbent Adsorption capacity (g / g) Adsorption (wt%) Example 1 0.239 23.9 Example 2 0.205 20.5 Comparative Example 0.073 7.3

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. Various modifications and variations are possible within the scope of the appended claims.

Claims (7)

An acidic mine drainage storing process for receiving and storing the acidic mine drainage;
An inorganic binder for precipitating mixed sludge of an inorganic binder-iron hydroxide in a three-dimensional network structure by adding caustic soda (NaOH) or liquid caustic soda (Ca (OH) ₂ ) and an inorganic binder to an acid mine drainage and stirring the mixed sludge; A production process;
A sludge dewatering step of dewatering the mixed sludge of the precipitated inorganic binder-iron hydroxide;
A process for producing an adsorbent for removing sulfur compounds using acidic mine drainage, comprising the step of extruding and drying a mixed sludge of an inorganic binder-iron hydroxide dehydrated through a sludge dewatering process into a pellet, and drying the same to form an adsorbent. The process according to claim 1, wherein the mineral binder-iron hydroxide mixed sludge production process is characterized in that caustic soda (NaOH) or liquid calcium hydroxide (Ca (OH) ₂ ) is added so that the acid mine drainage is maintained at a pH of 8 to 9.5 A method for preparing an adsorbent for removing sulfur compounds using drainage. The method of claim 1, wherein the inorganic binder is at least one selected from the group consisting of silica sol, bentonite, clay, mica, kaolin, montmorillonite, and modified silicate. The method of claim 1, wherein the inorganic binder is mixed in an amount of 0.1 to 0.5 weight (g) based on 13 L of acid mine drainage. The method for producing an adsorbent for removing sulfur compounds according to claim 1, wherein the inorganic binder-iron hydroxide mixed sludge is further added with a flocculant to rapidly precipitate iron hydroxide. [7] The method of claim 5, wherein the flocculant is added at 5-10 ppm with respect to the acid mine drainage. The method of claim 1, wherein the adsorbent forming process comprises drying the mixture at a temperature of 100 ° C to 120 ° C for 3 to 6 hours after extrusion molding.

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