KR100388631B1 - Manufacturing Method of Pelletizied Adsorbent for Waste Water Treatment Using Highly Unburned Carbon Fly Ash - Google Patents

Abstract

The present invention relates to a method for producing a molded adsorbent for wastewater treatment using high carbon coal ash which is disposed in large quantities in a thermal power plant.

The manufacturing method of the molded adsorbent for wastewater treatment using high carbon coal ash

60 to 70 wt% of raw material, 15 to 20 wt% of coal tar pitch, 2 to 3 wt% of pitch solvent, 2 to 3 wt% of binder additive, 4 to 6 wt% of catalyst, 8 to 12 wt% of water Wow;

Mixing at 50 to 60 ° C. after the step;

Compressing and molding after the step to produce pellets;

After the step, the pellet was put in the kiln and injected with nitrogen at 20 ml / min for carbonization at a temperature of 550 to 650 ° C. for 30 to 90 minutes;

Stopping the nitrogen supply after the step and activating by supplying steam preheated to 200 ° C. with 1 g-steam / hr · g-coal;

After the activation step is characterized in that it comprises the step of slowly cooling while supplying nitrogen at 20ml / min to stop the supply of water vapor.

On the other hand, the raw material is a high carbon coal ash or a mixture of 50 to 100 wt% of anthracite coal based on 100 wt% of high carbon coal ash and high carbon coal ash.

Description

Manufacturing Method of Pelletizied Adsorbent for Waste Water Treatment Using Highly Unburned Carbon Fly Ash}

The present invention relates to a method for producing a molded adsorbent for wastewater treatment using high carbon coal ash which is disposed in large quantities in a thermal power plant.

Domestic coal-fired power plants use domestic anthracite coal and bituminous coal imported from abroad as fuel.In this case, coal is pulverized (passed 70-80% with 200mesh sieve) and injected into the combustion furnace with air at high temperature. Most of the fine ash remaining after burning at 1,500 ± 200 ° C is discharged with the combustion gases. Such a material is called coal ash, and the coal used in Korea is not only anthracite coal but also bituminous coal imported from various varieties from abroad.

Most of the coal ash recycled in Korea is used as a raw material for concrete admixture and cement, and it can be seen that its utilization range is wide because it recycles the inorganic components that make up most of the coal ash. In order to recycle coal ash, unburned carbon powder which has a great influence on the strength of concrete must be removed. A physical method of classification is used to separate unburned carbon powder from coal ash. At this time, after classifying, coal ash having low unburned carbon (low carbon coal ash) is recycled, but coal ash having a high amount of unburned carbon (high carbon coal ash) has a problem of re-disposal. Therefore, if the high-carbon coal ash is efficiently reused, it will not only solve the problem of securing a place by re-disposal but also obtain the effect of pursuing high value-added interest rate by commercializing waste. However, the carbon component is SiO, which is the main component of coal ash.₂, Al₂O₃Inorganic materials such as and other organic components have different properties, so there is a lot of difficulties in using high carbon coal ash.

The present invention aims to produce a molded adsorbent that can be used for a long time while maximizing the use of unburned carbon components contained in a large amount of high carbon coal ash. To this end, it is intended to prepare an adsorbent having improved adsorptive capacity by adding a coal tar pitch, which is a caking agent, to a fine carbon coal ash made of fine powder, and preparing the pellets to undergo carbonization and activation. Such a method is contained in the high carbon coal ash to activate the unburned carbon to improve the adsorption capacity, and at the same time to produce a molded adsorbent, such as granulated activated carbon, to be made available for a long time by continuous adsorption / regeneration. In addition, the adsorbent prepared in the present invention can be utilized for removing biologically active carriers, sewage, AOS, heavy metals.

1 is a manufacturing method of the adsorbent according to the present invention,

2 is a manufactured pellet,

3 is a scanning micrograph (10,000 magnification) of a Type I adsorbent,

4 is a test result of living sewage removal using an adsorbent,

5 is a test result of AOS surfactant removal using an adsorbent,

6 is a heavy metal removal experiment using an adsorbent,

7 is a nitrification apparatus,

FIG. 8 shows the results of ammonia nitrogen removal using Type I, activated carbon, and glass dictates as biological carriers. FIG.

Method for producing a molded adsorbent for wastewater treatment using the high carbon coal ash of the present invention for achieving the above object

60 to 70 wt% of raw material, 15 to 20 wt% of coal tar with softening point of 85 ° C or more as caking agent, 2 to 3 wt% of heavy oil as pitch solvent, 2 to 3 wt% of starch or molasses as binder additive, CaCO as catalyst Grinding 4 to 6 wt% of metal carbonate, such as ₃ or K ₂ CO _3, and 8 to 12 wt% of water;

Mixing for 30 to 60 minutes at 50 to 60 ° C. after the step;

Compressing and molding after the step to produce pellets;

After the step, the pellet was put in a kiln and injected with nitrogen at 10 to 30 ml / min to carbonize at a temperature of 550 to 650 ° C. for 30 to 90 minutes;

Stopping the nitrogen supply after the step and supplying water vapor preheated to 150 to 220 ° C. with 1 g-steam / hr · g-coal to activate at 750 to 950 ° C. for 1 to 3 hours;

After the activation step it is characterized in that it comprises the step of slowly cooling while supplying nitrogen at 10 to 30ml / min after stopping the supply of steam (see Figure 1).

On the other hand, the raw material is a high carbon coal ash or a mixture for increasing the strength of the adsorbent, using a mixture of 50-100 wt% of anthracite coal based on 100 wt% of high carbon coal ash with high carbon coal ash.

As for the role of the material used in addition to the raw material, the pitch solvent is used to increase the adhesion between the coal ash and the coal tar pitch, and the binder additive controls the roughness of the surface of the adsorbent and is assembled during assembly. The catalyst is used to facilitate the activation of the adsorbent in the manufacture of the adsorbent to promote the generation of active pores, and the water to facilitate the mixing of the adsorbent when mixing to assist in the formation of appropriate pellets.

Referring to the manufacturing method of the molded adsorbent for wastewater treatment using the high carbon coal ash of the present invention in more detail as follows.

In order to add domestic anthracite to high-carbon coal ash, it was pulverized in a mill such as a ball mill for 4 hours and passed through a 200mesh sieve more than 95%. Coal tar pitch as a binder for coal ash, anthracite powder, heavy oil as pitch solvent, starch or molasses as binder additive, metal carbonate such as CaCO ₃ or K ₂ CO ₃ as catalyst, After addition, it mixes at 50-60 degreeC.

The mixed samples were compressed and molded at a pressure of 3 to 8 atm using a pelletizer to prepare cylindrical pellets having a size of 6 mm × Ø 3 mm.

The prepared pellet is injected into a rotary kiln and the kiln is rotated for uniform reaction of the injected raw material.

In order to prevent oxidation in the reactor, nitrogen was injected into the kiln at 10 to 30 ml / min and carbonized at 550 to 650 ° C. for 30 to 90 minutes.

After the carbonization process, the nitrogen supply was stopped and the steam preheated to 150 ~ 220 ℃ was supplied to 1g-steam / hr · g-coal to activate optimum reactor hole and activated at 750 ~ 950 ℃ for 1 ~ 3 hours. Maintained.

After the activation, the supply of water vapor is stopped and slowly cooled while injecting nitrogen at 10 to 30 ml / min to finally prepare the adsorbent.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the scope of the present invention is not limited by the following examples.

Example 1

The coal ash used in the experiment is a high-carbon coal ash with a lot of unburned carbon powder separated by classification that is produced in Seocheon thermal power plant and has the properties shown in Table 1. The composition and physical properties of high carbon coal ash may vary depending on the location of coal production and the combustion conditions of the thermal power plant.

Table 1. Industrial Analysis and Composition of High Carbon Fly Ash

Industrial analysis (wt%) Ingredient Mineral (wt%) Heavy metals (mg / g) moisture Volatility Ash Fixed carbon SiO ₂ Al ₂ O ₃ Fe ₂ O ₃ CaO MgO Cr V Cu Pb Zn - - 92.7 7.3 53.12 26.29 7.71 3.94 1.23 71 136 59 44 78

Example 2

60 to 70 wt% of the high carbon coal ash sample of Example 1, 15 to 20 wt% of coal tar pitch having a softening point of 85 ° C. or more as a binder, 2 to 3 wt% of heavy oil as a pitch solvent, and 2 to 3 starch or molasses as a binder additive. wt%, 4 to 6 wt% of metal carbonate K ₂ CO ₃ as catalyst and 8 to 12 wt% of water were used as raw materials for the adsorbent.

Table 2 shows the optimum mixing ratio of the mixture used to promote molding and activation. The mixed sample was compressed and molded under a condition of 3 to 8 atm using a pelletizer, and the cylindrical pellets thus formed were shown in FIG. 2.

Table 2. Properties and Mixing Ratios of Raw Materials Used in Adsorbents

Raw material name Industrial analysis (wt%) Packing density (g / ml) Compounding ratio (wt%) moisture Volatility Ash Fixed carbon High carbon coal ash - - 92.7 7.3 0.795 63.9 Kooltar Pitch - 99.90 0.10 - 0.672 17.9 Pitch Solvent 0.55 60.75 38.70 - 0.803 1.9 Binder additive 0.03 28.33 76.64 - 0.572 1.6 Catalyst - 99.0 - - 1.126 5.1 water 100.0 - - - 1.000 9.6

Example 3

In order to improve the strength and adsorption performance of the high carbon coal ash of Example 1, high carbon coal ash and Jangseong coal, which is domestic anthracite coal (water 3.8wt%, volatile matter 9.9wt%, ash 36.1wt%, fixed carbon 50.2wt%) To prepare a pellet was mixed, the compounding ratio and industrial analysis results are shown in Table 3.

Except the raw materials in Table 3, the additives were mixed in the same ratio as in Example 2. In this case, the type I pellets prepared by mixing only 63.9 wt% of high carbon coal ash were prepared in the form of pellets prepared by mixing 50:50 ratio of type I, high carbon coal ash and Jangjae charcoal. wt%: 31.95 wt%), and a pellet containing a mixture of high-carbon coal ash and long charcoal at a ratio of 75:25 was designated as Type III (high carbon coal ash: long carbon charcoal = 48 wt%: 15.9 wt%). The prepared pellets were carbonized for 30 to 90 minutes at 550 to 650 ° C and activated for 1 to 3 hours at 750 to 950 ° C to prepare a final adsorbent.

Table 3. Industrial Analysis of Pellets by Blending High Carbon Fly Ash and Chang Char

Raw material name Compounding cost Volatilization (wt%) Ash (wt%) Fixed Carbon (wt%) ¹⁾ (wt%) ²⁾ (wt%) of raw material mixture Type Ⅰ FA ³⁾ (63.9) FA (100) 19.37 64.31 16.32 Type II FA: JA ³⁾ (31.95: 31.95) FA: JA (50:50) 21.43 47.36 31.32 Type Ⅲ FA: JA (48: 15.9) FA: JA (75:25) 16.45 55.05 28.50

1) Total compounding ratio of raw materials for pellet assembly

2) Mixing ratio based on coal ash and Jangseong coal among raw materials

3) FA: high carbon coal ash, JA: Jangseongtan

In order to use as adsorbent for water treatment that can be used for a long time, the iodine value, which is an indicator of strength and adsorption performance of the adsorbent prepared as the most important item when the adsorbent / regeneration is continuously maintained, that is, strength is the most important item Shown in In the case of Type I using only high carbon coal ash in Table 4, the strength is 89.3%. In the quality standard of granular activated carbon according to KS M1421, when the primary activated carbon is 90% or more, it can be used as a substitute for the activated activated carbon. In the case of Type II using 31.95wt% of total carbon except for additives, the strength increased to 95.3% and the adsorption value of iodine was 257.7mg / g. Also, in the case of Type III using 15.9wt% of carbon. The strength increased to 96.3% and iodine adsorption to 287.6 mg / g. This shows that the strength and iodine value can be increased by increasing the mixing ratio of the charcoal.

On the other hand, the iodine adsorption value was measured by the adsorption capacity of the adsorbent was set to the activated carbon test method (KS M 1802).

Table 4. Variation of Adsorbent Strength and Iodine Adsorption Rate According to Changes in Enteric Carbon Mixture

Type Wall Charcoal Mixing Ratio carbonization Activation Temperature (℃) Hours (hr) Temperature (℃) Hours (hr) burglar(%) Iodine adsorption value (mg / g) Type Ⅰ 0% 600 2 850 One 89.3 106.9 Type Ⅲ 25% 600 2 850 2 95.3 257.7 Type II 50% 600 2 850 2 96.3 287.6

Example 4

The photograph of the surface of the Type I adsorbent of the adsorbent prepared in Example 3 by scanning electron microscope is shown in FIG. 3. 3 shows that the large pores are formed on the surface of the adsorbent, which increases the contact area with contaminants during water treatment, thereby increasing the adsorption capacity, and in particular, can provide a breeding space for microorganisms when used as a bioactive carrier.

Test Example 1 Removal Performance for Wastewater

The removal performance of the sewage water was tested using the adsorbent prepared in Example 3. The sewage wastewater was collected from the first sedimentation tank supernatant of the sewage terminal treatment plant to treat domestic sewage and used as a pretreatment. The initial COD _Mn concentration was 19.6 mg / l and the results of the removal experiments are shown in FIG. 4.

The removal rate was 75.53%, 72.70%, 76.79% for Calgon (Cal), Norit, and Kuraray (Ku), which were commercially available activated carbon. High-carbon coal ash has a removal rate of 5.7%, while carbonized and activated Type I and Type II have high removal rates of 65.2% and 67.14%. If the removal rate of activated carbon is 100%, Type I and Type II are 87.7% and 90.3%, showing almost the same adsorption capacity compared to activated carbon. These results are due to the increase in pore development of the carbon component, which is an organic substance in the coal ash, and the removal efficiency due to the surface activation of Si, Al, and Fe oxides, which are the main components of the coal ash.

COD (Chemical Oxygen Demand) removal rate experiment was pulverized adsorbent to 200 mesh or more, dried at 110 ℃ for 2 hours, and added to a certain amount of adsorbent in 100ml waste water and stirred until reaching equilibrium time equilibrium time When reached, the adsorbent was filtered and the COD _Mn of the filtrate was measured.

Test Example 2 Removal Performance for Surfactant

The removal performance for the surfactant was tested using the adsorbent prepared in Example 3. Surfactants, which are currently a problem in wastewater flowing into rivers, are used in the cleaning, emulsifying and deinking industry, and the dispersion and foaming of the surfactants make water treatment difficult. As the surfactant, AOS (Alpha-Olefin-Sulfonate), an anionic surfactant that has been widely used these days, was selected. The removal experiment was performed by making artificial wastewater of COD _Mn 100 mg / L with the AOS surfactant, and the results are shown in FIG. 5. The removal rate was 89.9%, 87.3% and 88.7% for Calgon, Norit and Kuraray, which were commercially available activated carbons. High-carbon coal ash has a removal rate of 56.3%, while carbonized and activated Type I and Type II have high removal rates of 79.7% and 83.8%. If the removal rate of activated carbon is 100%, high-carbon coal ash, Type I and Type II, shows high removal rate of 63.5%, 89.9% and 94.6%.

Test Example 3 Removal Performance for Heavy Metals

The removal performance of heavy metals (lead, manganese, chromium) was tested using the adsorbent prepared in Example 3, and the results are shown in FIG. Type I and Type II show superior removal to Pb and Cr. However, high-carbon coal ash and commercially available activated carbon show low removal rates.

Heavy metal removal test method is to pulverize adsorbent more than 200mesh, dry at 110 ℃ for 2 hours, add 1g adsorbent to 100ml waste water, shake in 60 ℃ water bath for 60 hours The adsorbents were separated by using. The concentration of the heavy metals was finally measured using an inductively coupled plasma (ICP) apparatus.

Test Example 4 Ammonia Nitrogen Removal Performance as Bioactive Carrier

Activated charcoal and glass dictation were used as comparative performance evaluation adsorbents in order to investigate the possibility of activity as a bioactive carrier of the Type I adsorbent prepared in Example 3, and a diagram of a biological test apparatus is shown in FIG. 7. In FIG. 7 the column was made of a double acrylic tube. The inside of the double tube was filled with an adsorbent in the reactor, and water having a constant temperature circulated outside the double tube to maintain the temperature of the reactor. The column internal reaction tank 1 is 1.3 L of 80 mm in diameter and 260 mm in length. The reactor was formed by placing sieves (ø 3 mm) at intervals of 40 mm, and each layer was filled with 20 mm of an adsorbent. The circulating water outside the double tube was kept at a temperature of 31.2 ± 0.1 ° C. using a constant temperature circulation tank. Two thermocouples 3 were installed to measure the temperature of the water flowing into the reactor and the water flowing out of the reactor. A bubble generator 4 was placed at the bottom of the reactor to supply oxygen for nitrification. A water tank (5) having an effective volume of 2.4 liters was installed so that the water passed through the reaction tank was mixed with the simulated wastewater in the water tank to be introduced again into the reactor at a constant rate of 30 ml / min through the pump. The simulated wastewater was introduced into the tank at 3.5 ml / min. The stirrer 7 was attached to completely mix the water passed through the reactor into the tank and the simulated waste water. In addition, a bubble generator was installed at the bottom of the tank to supply sufficient dissolved oxygen. The simulated wastewater was stored in a storage tank (6) with an effective volume of 60 L and stored at low temperature below 10 ° C. to prevent alteration and algae growth.

In the performance test, high carbon coal ash adsorbent (Type I), activated carbon (AC) and glass dictation (GB) having the properties shown in Table 5 were used as biocarriers. As a test method, the nitrate was circulated in the reaction tank for 3 days while the bacteria were attached to the adsorbent, and then the removal rate was measured while continuously injecting 100 ppm of ammonia nitrogen, which is a simulated wastewater. The results of the experiment for 9 days are shown in FIG. 8. When the removal rate of activated carbon was 100%, Type I was 83.7% and glass dictation was 37.4%. Therefore, the adsorbent prepared by the high carbon coal circuit is slightly lower in removal efficiency than activated carbon, but the manufacturing cost is low, and thus it is highly applicable to the bioactive carrier.

Ammonia nitrogen represents the amount of ammonia (NH ₃ ) present in the form of ions (NH ₄ ⁺ ) in water as the amount of nitrogen. The ammonia nitrogen removal experiment was performed in the same manner as the heavy metal removal experiment. In order to analyze the ammonia concentration, a measuring device of HACH DR / 4000 was used. The concentration of ammonia nitrogen was measured using the Nessler method, where the absorption wavelength of ammonia nitrogen was 425 nm.

Table 5. Physical Properties of Adsorbents Filled in Reactors

Type I adsorber Coal-based activated carbon glass marble Media diameter 4 mm 4 mm 4 mm Media way 6 to 7 mm 6 to 7 mm - Iodine adsorption amount (I ₂ ) 106 mg / g 1,012 mg / g - Surface Area (B.E.T.) 56.5 ㎡ / g 989.5 ㎡ / g - Average Pore 27 Å 12 Å - Hardness 85% 96% - Filling wheat road 0.77 g / ml 0.53 g / ml 1.45 g / ml Filling volume 400 ml 400 ml 400 ml Fill amount 309 g 213 g 580 g

As can be seen through the above examples and experimental examples, the present invention, along with the coal tar pitch using unburned carbon components contained in a large amount of high carbon coal ash as a caking agent, by producing an adsorbent improved performance through the activation process sewage water As it shows excellent removal performance against heavy metals, AOS and heavy metals, it is highly likely to be used as an alternative adsorbent for activated carbon that is currently used universally. In addition, it has excellent bioadhesive properties and can be used as an active carrier for ammonia nitrogen removal which causes eutrophication in wastewater. Above all, the high-carbon coal ash, which is currently being recycled, can be used to improve the resource utilization rate and to produce the adsorbent at a low price.

Claims (5)

60 to 70 wt% of raw material, 15 to 20 wt% of coal tar pitch having a softening point of 85 ° C. or higher, 2 to 3 wt% of pitch solvent, 2 to 3 wt% of binder additive, 4 to 6 wt% of catalyst, 8 to 12 wt of water Grinding%; Mixing for 30 to 60 minutes at 50 to 60 ° C. after the step; Compressing and molding after the step to produce pellets; After the step, the pellet was put in a kiln and injected with nitrogen at 10 to 30 ml / min to carbonize at a temperature of 550 to 650 ° C. for 30 to 90 minutes; Stopping the nitrogen supply after the step and activating by supplying steam preheated to 150 to 220 ° C. with 1 g-steam / hr · g-coal; Method of producing a molded adsorbent for wastewater treatment using high carbon coal ash, characterized in that the step of stopping the supply of steam after the activation step and injecting nitrogen at 10 to 30ml / min slowly The method of claim 1, wherein the raw material is a high-carbon coal ash, or a mixture of 50-100 wt% anthracite coal with high carbon coal ash based on 100 wt% of high carbon coal ash. Manufacturing method of adsorbent The method of claim 1, wherein the pitch solvent is a heavy oil. The method of claim 1, wherein the binder additive is starch or molasses. The method of claim 1, wherein the catalyst is CaCO ₃ or K ₂ CO ₃ .