Preparation method of activated carbon for low-iron high-sugar food

Abstract

This invention relates to a method for preparing activated carbon specifically for low-iron, high-sugar foods, belonging to the technical field of coal-based activated carbon. The method includes: A. Selecting coking coal with a moisture content ≤1 wt.%, ash content ≤10 wt.%, volatile matter content 16-29 wt.%, and Fe content ≤1.0 wt.%, and blending it with Datong weakly caking coal with a moisture content 1.5-7.7 wt.%, ash content 2.5-8.2 wt.%, volatile matter content 28-35 wt.%, and Fe content ≤1.0 wt.% at a mass ratio of (3-4):1, and pulverizing the coal to... A. Particle size less than 2mm; B. Magnetic separation; C. Pressing and molding; D. Carbonization; E. Activation treatment of the material: saturated steam at 130-150℃ is added from the bottom of the furnace, the furnace temperature is controlled at 750-850℃, activation is performed for 50-60 minutes, then the temperature is raised to 850-950℃, the exhaust port is closed halfway, activation treatment is performed for 2-3 hours, the exhaust port is opened, and activation treatment is continued at 850-950℃ for 10-15 hours; F. The material undergoes secondary magnetic separation, acid washing, water washing, alkali washing, water washing, and drying to obtain low-iron, high-sugar food-grade activated carbon. The activated carbon prepared by this invention has strong decolorizing power, large adsorption capacity, low iron content, and high strength.

Description

Technical Field

[0001] This invention belongs to the technical field of coal-based activated carbon, and relates to a special activated carbon for low-iron, high-sugar foods. Specifically, it relates to a method for preparing the special activated carbon for low-iron, high-sugar foods. The activated carbon prepared by this invention has strong decolorization power, large adsorption capacity, low iron content, and high strength. Background Technology

[0002] The earliest application of activated carbon in liquid-phase decolorization and refining was in the sugar and fermentation industries. Developed countries began using activated carbon on a large scale for sugar decolorization and refining as early as the 1930s. With the improvement of living standards and health awareness among Chinese residents, the relevant national authorities will inevitably place higher demands on sugar processing technology, and activated carbon decolorization will eventually become the main refining method in my country's sugar industry. Typically, the amount of activated carbon consumed in sugar decolorization is about 0.5-1.0% of the sugar content. Since the reform and opening up, my country's grain conversion industries, such as fermentation, have developed rapidly, with a leapfrog increase in the production of starch sugars, citric acid, and monosodium glutamate. Activated carbon is indispensable in the production and refining processes of these products, and their exponential increase will inevitably lead to a corresponding exponential increase in the demand for activated carbon.

[0003] Currently, the iron content of coal-based activated carbon used in food refining and decolorization is required to be less than 300 ppm. However, with the improvement of people's living standards, the requirements for the performance and indicators of activated carbon are also increasing. Producing food-grade activated carbon with ultra-low iron content and high sugar adsorption is an urgent problem to be solved. Summary of the Invention

[0004] In order to solve the above-mentioned technical problems, the present invention provides a method for preparing activated carbon for low-iron, high-sugar foods. The prepared activated carbon has low iron content and high adsorption performance, and can be widely used in food refining, decolorization and other fields.

[0005] The technical solution adopted by this invention to achieve its purpose is as follows:

[0006] A method for preparing activated carbon specifically for low-iron, high-sugar foods includes the following steps:

[0007] A. Select coking coal with a moisture content ≤1wt.%, ash content ≤10wt.%, volatile matter content 16-29wt.%, and Fe content ≤1.0wt.%, and Datong weakly caking coal with a moisture content 1.5-7.7wt.%, ash content 2.5-8.2wt.%, volatile matter content 28-35wt.%, and Fe content ≤1.0wt.%, and blend them at a mass ratio of (3-4):1, and crush them to a particle size of less than 2mm;

[0008] B. Place the pulverized material from step A into a magnetic separator for magnetic separation;

[0009] C. The magnetically separated material is pressed into shape using a dry roller briquetting machine;

[0010] D. Crush the pressed material to a particle size of 4-10mm, and then place it in a carbonization furnace for carbonization treatment;

[0011] E. Place the carbonized material in a Sleip furnace for activation treatment. Add saturated steam at 130-150℃ from the bottom of the furnace, control the furnace temperature at 750-850℃, activate for 50-60 minutes, then raise the temperature to 850-950℃, close the flue gas outlet halfway, activate for 2-3 hours, open the flue gas outlet and continue activation treatment at 850-950℃ for 10-15 hours.

[0012] F. The activated material is subjected to secondary magnetic separation, acid washing, water washing, alkali washing, water washing, and drying to obtain low-iron, high-sugar food-grade activated carbon.

[0013] Furthermore, the magnetic field strength for magnetic separation in step B is 600-800 GS.

[0014] Furthermore, before step B magnetic separation, the material is dried at 130-150℃ for 10-15 minutes.

[0015] Further, the carbonization described in step D involves first placing the material in a first carbonization furnace for preliminary carbonization for 20-30 minutes. The inlet temperature of the first carbonization furnace is 100-150℃, the heating rate is 11-12℃ / min, the outlet temperature is 300-350℃, and the rotation speed of the first carbonization furnace is 1-3 r / min. Then, the material is placed in a second carbonization furnace for deep carbonization for 2-3 hours. The inlet temperature of the second carbonization furnace is 400-450℃, the heating rate is 15-16℃ / min, the outlet temperature is 700-800℃, and the rotation speed of the second carbonization furnace is 1-3 r / min.

[0016] Further, the pickling in step F is as follows: the activated material is placed in an acid solution at 60-80℃ and ultrasonically vibrated at 220-240W power for 30-40 minutes.

[0017] Furthermore, the acid solution is obtained by mixing hydrochloric acid with a concentration of 8-11%, sulfuric acid with a concentration of 20-28%, and nitric acid with a concentration of 7-12% in a volume ratio of 2:2:1.

[0018] Furthermore, the water washing in step F involves rinsing at least three times with 3-4 times the volume of deionized water.

[0019] Further, the alkaline washing in step F is as follows: the material is placed in a 10-20% sodium hydroxide solution at 40-50℃ and ultrasonically vibrated at 220-240W power for 15-20 minutes.

[0020] Furthermore, the magnetic field strength of the secondary magnetic separation in step F is 800-1000GS.

[0021] The beneficial effects of this invention are:

[0022] The present invention obtains activated carbon with low iron content, as low as below 70 ppm, through coal preparation and blending, two magnetic separations, carbonization, activation, acid washing, water washing and alkali washing, which significantly reduces the iron content.

[0023] The preparation method of this invention optimizes raw materials and processes, resulting in activated carbon with high iodine adsorption value, high methylene blue adsorption value, high strength, low ash content, low floating rate, and high caramel decolorization rate, making it suitable for refining and decolorizing in the food industry. Detailed Implementation

[0024] The present invention will now be described in detail with reference to specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort should fall within the scope of protection of the present invention. Specific Implementation

[0025] Example 1

[0026] A method for preparing activated carbon specifically for low-iron, high-sugar foods includes the following steps:

[0027] A. Select coking coal with a moisture content of 0.8 wt.%, ash content of 8.5 wt.%, volatile matter content of 20.8 wt.%, and Fe content of 0.8 wt.%, and Datong weakly caking coal with a moisture content of 4.2 wt.%, ash content of 6.7 wt.%, volatile matter content of 30.1 wt.%, and Fe content of 0.8 wt.%, and blend them at a mass ratio of 3:1. Then crush them to a particle size of less than 2 mm.

[0028] B. Dry the pulverized material from step A at 150°C for 10 minutes, and then place it in a magnetic separator with a magnetic field strength of 600GS for magnetic separation;

[0029] C. The magnetically separated material is pressed into shape using a dry roller briquetting machine;

[0030] D. The pressed material is crushed to a particle size of 5mm, and then placed in the first carbonization furnace for preliminary carbonization for 30min. The inlet temperature of the first carbonization furnace is 100℃, the heating rate is 11℃ / min, the outlet temperature is 300℃, and the rotation speed of the first carbonization furnace is 2r / min. Then it is placed in the second carbonization furnace for deep carbonization for 3h. The inlet temperature of the second carbonization furnace is 400℃, the heating rate is 15℃ / min, the outlet temperature is 700℃, and the rotation speed of the second carbonization furnace is 2r / min.

[0031] E. Place the carbonized material in a Sleip furnace for activation treatment. Add saturated steam at 130°C from the bottom of the furnace, control the furnace temperature at 800°C, activate for 50 minutes, then raise the temperature to 910°C, close the flue gas outlet halfway, activate for 3 hours, and then open the flue gas outlet to continue activation treatment at 910°C for 15 hours.

[0032] F. The activated material is placed in a magnetic separator with a magnetic field strength of 800GS for secondary magnetic separation. Then, the material is placed in an acid solution at 75℃ and ultrasonically vibrated at 240W for 30 minutes. The acid solution is prepared by mixing 10% hydrochloric acid, 28% sulfuric acid and 11% nitric acid in a volume ratio of 2:2:1. The material is then rinsed 5 times with 4 times the volume of deionized water. The material is then placed in a 20% sodium hydroxide solution at 50℃ and ultrasonically vibrated at 240W for 20 minutes. It is then rinsed 5 times with 4 times the volume of deionized water and dried to obtain activated carbon for low-iron and high-sugar food.

[0033] The obtained activated carbon was tested according to the standard GB / T 7702.3-2008 Test Method for Coal-based Granular Activated Carbon, and the strength was found to be 96%.

[0034] The obtained activated carbon was tested according to the standard GB / T 7702.6-2008 Test Method for Methylene Blue Adsorption Value of Coal-based Granular Activated Carbon, and the methylene blue adsorption value was found to be 234.7 mg / g.

[0035] The obtained activated carbon was tested according to the standard GB / T 7702.7-2008 Test Method for Iodine Adsorption Value of Coal-based Granular Activated Carbon, and the iodine adsorption value was found to be 1165 mg / g.

[0036] The obtained activated carbon was tested according to the standard GB / T 7702.15-2008 Test Method for Determination of Ash Content of Coal-based Granular Activated Carbon, and the ash content was found to be 1.4%.

[0037] The obtained activated carbon was tested according to the standard GB / T 7702.17-2008 Test Method for Flotation Rate of Coal-based Granular Activated Carbon, and the flotation rate was found to be 1.2%.

[0038] The obtained activated carbon was tested according to the standard GB / T 7702.18-2008 Test Method for Coal-based Granular Activated Carbon - Determination of Caramel Decolorization Rate. The caramel decolorization rate of Method A was found to be 100%.

[0039] The Fe content was determined according to the MT / T1068-2008 standard, and the Fe content was found to be 61 ppm.

[0040] Example 2

[0041] A method for preparing activated carbon specifically for low-iron, high-sugar foods includes the following steps:

[0042] A. Select coking coal with a moisture content of 0.75 wt.%, ash content of 7.9 wt.%, volatile matter content of 23.9 wt.%, and Fe content of 0.85 wt.%, and Datong weakly caking coal with a moisture content of 4.6 wt.%, ash content of 7.4 wt.%, volatile matter content of 31.3 wt.%, and Fe content of 0.75 wt.%, and blend them at a mass ratio of 4:1. Then crush them to a particle size of less than 2 mm.

[0043] B. Dry the pulverized material from step A at 130°C for 15 minutes, and then place it in a magnetic separator with a magnetic field strength of 700GS for magnetic separation;

[0044] C. The magnetically separated material is pressed into shape using a dry roller briquetting machine;

[0045] D. The pressed material is crushed to a particle size of 4mm, and then placed in the first carbonization furnace for preliminary carbonization for 20min. The inlet temperature of the first carbonization furnace is 150℃, the heating rate is 12℃ / min, the outlet temperature is 350℃, and the rotation speed of the first carbonization furnace is 1r / min. Then it is placed in the second carbonization furnace for deep carbonization for 2h. The inlet temperature of the second carbonization furnace is 450℃, the heating rate is 16℃ / min, the outlet temperature is 800℃, and the rotation speed of the second carbonization furnace is 1r / min.

[0046] E. Place the carbonized material in a Sleip furnace for activation treatment. Add saturated steam at 150°C from the bottom of the furnace, control the furnace temperature at 750°C, activate for 60 minutes, then raise the temperature to 850°C, close the flue gas outlet halfway, activate for 2.5 hours, and then open the flue gas outlet to continue activation treatment at 850°C for 12 hours.

[0047] F. The activated material is placed in a magnetic separator with a magnetic field strength of 900GS for secondary magnetic separation. Then, the material is placed in an acid solution at 60℃ and ultrasonically vibrated at 220W for 40 minutes. The acid solution is prepared by mixing 11% hydrochloric acid, 20% sulfuric acid and 12% nitric acid in a volume ratio of 2:2:1. The material is then rinsed 6 times with 3 times the volume of deionized water. The material is then placed in a 10% sodium hydroxide solution at 40℃ and ultrasonically vibrated at 220W for 15 minutes. It is then rinsed 6 times with 3 times the volume of deionized water and dried to obtain low-iron, high-sugar food-grade activated carbon.

[0048] The obtained activated carbon was tested according to the standard GB / T 7702.3-2008 Test Method for Coal-based Granular Activated Carbon, and the strength was found to be 96%.

[0049] The obtained activated carbon was tested according to the standard GB / T 7702.6-2008 Test Method for Methylene Blue Adsorption Value of Coal-based Granular Activated Carbon, and the methylene blue adsorption value was found to be 241.2 mg / g.

[0050] The obtained activated carbon was tested according to the standard GB / T 7702.7-2008 Test Method for Iodine Adsorption Value of Coal-based Granular Activated Carbon, and the iodine adsorption value was found to be 1127 mg / g.

[0051] The obtained activated carbon was tested according to the standard GB / T 7702.15-2008 Test Method for Ash Content of Coal-based Granular Activated Carbon, and the ash content was found to be 1.3%.

[0052] The obtained activated carbon was tested according to the standard GB / T 7702.17-2008 Test Method for Flotation Rate of Coal-based Granular Activated Carbon, and the flotation rate was found to be 1.1%.

[0053] The obtained activated carbon was tested according to the standard GB / T 7702.18-2008 Test Method for Coal-based Granular Activated Carbon - Determination of Caramel Decolorization Rate. The caramel decolorization rate of Method A was found to be 100%.

[0054] The Fe content was determined according to the MT / T1068-2008 standard, and the Fe content was found to be 68 ppm.

[0055] Example 3

[0056] A method for preparing activated carbon specifically for low-iron, high-sugar foods includes the following steps:

[0057] A. Select coking coal with a moisture content of 0.77 wt.%, ash content of 9.2 wt.%, volatile matter content of 20.7 wt.%, and Fe content of 0.88 wt.%, and Datong weakly caking coal with a moisture content of 4.6 wt.%, ash content of 5.6 wt.%, volatile matter content of 29.5 wt.%, and Fe content of 0.62 wt.%, and blend them at a mass ratio of 4:1. Crush the coal to a particle size of less than 2 mm.

[0058] B. Dry the pulverized material from step A at 140℃ for 12 minutes, and then place it in a magnetic separator with a magnetic field strength of 800GS for magnetic separation;

[0059] C. The magnetically separated material is pressed into shape using a dry roller briquetting machine;

[0060] D. The pressed material is crushed to a particle size of 8mm, and then placed in the first carbonization furnace for preliminary carbonization for 25min. The inlet temperature of the first carbonization furnace is 130℃, the heating rate is 11℃ / min, the outlet temperature is 320℃, and the rotation speed of the first carbonization furnace is 3r / min. Then it is placed in the second carbonization furnace for deep carbonization for 2.5h. The inlet temperature of the second carbonization furnace is 430℃, the heating rate is 15℃ / min, the outlet temperature is 750℃, and the rotation speed of the second carbonization furnace is 3r / min.

[0061] E. Place the carbonized material in a Sleip furnace for activation treatment. Add saturated steam at 140°C from the bottom of the furnace, control the furnace temperature at 850°C, activate for 55 minutes, then raise the temperature to 950°C, close the flue gas outlet halfway, activate for 2 hours, and then open the flue gas outlet to continue activation treatment at 950°C for 10 hours.

[0062] F. The activated material is placed in a magnetic separator with a magnetic field strength of 1000GS for secondary magnetic separation. Then, the material is placed in an acid solution at 80℃ and ultrasonically vibrated at 240W for 30 minutes. The acid solution is prepared by mixing 8% hydrochloric acid, 24% sulfuric acid and 7% nitric acid in a volume ratio of 2:2:1. The material is then rinsed 5 times with 4 times the volume of deionized water. The material is then placed in a 15% sodium hydroxide solution at 50℃ and ultrasonically vibrated at 240W for 20 minutes. It is then rinsed 5 times with 4 times the volume of deionized water and dried to obtain activated carbon for low-iron and high-sugar food.

[0063] The obtained activated carbon was tested according to the standard GB / T 7702.3-2008 Test Method for Coal-based Granular Activated Carbon, and the strength was found to be 96%.

[0064] The obtained activated carbon was tested according to the standard GB / T 7702.6-2008 Test Method for Methylene Blue Adsorption Value of Coal-based Granular Activated Carbon, and the methylene blue adsorption value was found to be 228.3 mg / g.

[0065] The obtained activated carbon was tested according to the standard GB / T 7702.7-2008 Test Method for Iodine Adsorption Value of Coal-based Granular Activated Carbon, and the iodine adsorption value was found to be 1171 mg / g.

[0066] The obtained activated carbon was tested according to the standard GB / T 7702.15-2008 Test Method for Determination of Ash Content of Coal-based Granular Activated Carbon, and the ash content was found to be 1.0%.

[0067] The obtained activated carbon was tested according to the standard GB / T 7702.17-2008 Test Method for Flotation Rate of Coal-based Granular Activated Carbon, and the flotation rate was found to be 1.0%.

[0068] The obtained activated carbon was tested according to the standard GB / T 7702.18-2008 Test Method for Coal-based Granular Activated Carbon - Determination of Caramel Decolorization Rate. The caramel decolorization rate of Method A was found to be 100%.

[0069] The Fe content was determined according to the MT / T1068-2008 standard, and the Fe content was found to be 54 ppm.

[0070] Comparative Example 1

[0071] The difference from Example 1 is the activation treatment in step E, which is as follows: the carbonized material is placed in a Sleip furnace for activation treatment. First, it is activated at 800°C for 1 hour in a water vapor atmosphere, and then activated at 800°C for 10 hours in a mixed atmosphere consisting of 20% volume water vapor and 80% volume flue gas.

[0072] The obtained activated carbon was tested according to the standard GB / T 7702.3-2008 Test Method for Coal-based Granular Activated Carbon, and the strength was found to be 96%.

[0073] The obtained activated carbon was tested according to the standard GB / T 7702.6-2008 Test Method for Methylene Blue Adsorption Value of Coal-based Granular Activated Carbon, and the methylene blue adsorption value was found to be 182.6 mg / g.

[0074] The obtained activated carbon was tested according to the standard GB / T 7702.7-2008 Test Method for Iodine Adsorption Value of Coal-based Granular Activated Carbon, and the iodine adsorption value was found to be 895 mg / g.

[0075] The obtained activated carbon was tested according to the standard GB / T 7702.15-2008 Test Method for Ash Content of Coal-based Granular Activated Carbon, and the ash content was found to be 2.5%.

[0076] The obtained activated carbon was tested according to the standard GB / T 7702.17-2008 Test Method for Flotation Rate of Coal-based Granular Activated Carbon, and the flotation rate was found to be 2.3%.

[0077] The obtained activated carbon was tested according to the standard GB / T 7702.18-2008 Test Method for Coal-based Granular Activated Carbon - Determination of Caramel Decolorization Rate. The caramel decolorization rate of Method A was found to be 98%.

[0078] The Fe content was determined according to the MT / T1068-2008 standard, and the Fe content was found to be 138 ppm.

[0079] Comparative Example 2

[0080] The difference from Example 1 is the refining process in step F, which is as follows: the activated material is placed in a magnetic separator with a magnetic field strength of 1000GS for secondary magnetic separation, then the material is placed in a 24% sulfuric acid solution at 80°C for 36 hours, then rinsed 5 times with 4 times the volume of deionized water, then placed in a 15% sodium hydroxide solution at 50°C for 10 hours, then rinsed 5 times with 4 times the volume of deionized water, and dried to obtain activated carbon.

[0081] The obtained activated carbon was tested according to the standard GB / T 7702.3-2008 Test Method for Coal-based Granular Activated Carbon, and the strength was found to be 96%.

[0082] The obtained activated carbon was tested according to the standard GB / T 7702.6-2008 Test Method for Methylene Blue Adsorption Value of Coal-based Granular Activated Carbon, and the methylene blue adsorption value was found to be 196.2 mg / g.

[0083] The obtained activated carbon was tested according to the standard GB / T 7702.7-2008 Test Method for Iodine Adsorption Value of Coal-based Granular Activated Carbon, and the iodine adsorption value was found to be 983 mg / g.

[0084] The obtained activated carbon was tested according to the standard GB / T 7702.15-2008 Test Method for Determination of Ash Content of Coal-based Granular Activated Carbon, and the ash content was found to be 1.8%.

[0085] The obtained activated carbon was tested according to the standard GB / T 7702.17-2008 Test Method for Flotation Rate of Coal-based Granular Activated Carbon, and the flotation rate was found to be 1.4%.

[0086] The obtained activated carbon was tested according to the standard GB / T 7702.18-2008 Test Method for Determination of Caramel Decolorization Rate of Coal-based Granular Activated Carbon. The caramel decolorization rate of Method A was found to be 99%.

[0087] The Fe content was determined according to the MT / T1068-2008 standard, and the Fe content was found to be 194 ppm.

[0088] Comparative Example 3

[0089] The difference from Example 1 is the refining process in step F, which is as follows: the activated material is placed in a magnetic separator with a magnetic field strength of 1000GS for secondary magnetic separation, and then the material is placed in an acid solution at 80°C for 36 hours. The acid solution is obtained by mixing 8% hydrochloric acid, 24% sulfuric acid and 7% nitric acid in a volume ratio of 2:2:1. The material is then rinsed 5 times with 4 times the volume of deionized water. The material is then placed in a 15% sodium hydroxide solution at 50°C for 10 hours, and then rinsed 5 times with 4 times the volume of deionized water. After drying, activated carbon is obtained.

[0090] The obtained activated carbon was tested according to the standard GB / T 7702.3-2008 Test Method for Coal-based Granular Activated Carbon, and the strength was found to be 96%.

[0091] The obtained activated carbon was tested according to the standard GB / T 7702.6-2008 Test Method for Methylene Blue Adsorption Value of Coal-based Granular Activated Carbon, and the methylene blue adsorption value was found to be 202.7 mg / g.

[0092] The obtained activated carbon was tested according to the standard GB / T 7702.7-2008 Test Method for Iodine Adsorption Value of Coal-based Granular Activated Carbon, and the iodine adsorption value was found to be 1051 mg / g.

[0093] The obtained activated carbon was tested according to the standard GB / T 7702.15-2008 Test Method for Ash Content of Coal-based Granular Activated Carbon, and the ash content was found to be 1.7%.

[0094] The obtained activated carbon was tested according to the standard GB / T 7702.17-2008 Test Method for Flotation Rate of Coal-based Granular Activated Carbon, and the flotation rate was found to be 1.4%.

[0095] The obtained activated carbon was tested according to the standard GB / T 7702.18-2008 Test Method for Determination of Caramel Decolorization Rate of Coal-based Granular Activated Carbon. The caramel decolorization rate of Method A was found to be 99%.

[0096] The Fe content was determined according to the MT / T1068-2008 standard, and the Fe content was found to be 156 ppm.

[0097] Comparative Example 4

[0098] The difference from Example 1 is the carbonization treatment in step D, which is as follows: under oxygen-free conditions, the temperature is raised to 300°C at a heating rate of 3°C / min for 30 min for pre-carbonization, and then further carbonized at 600°C for 3 h.

[0099] The obtained activated carbon was tested according to the standard GB / T 7702.3-2008 Test Method for Coal-based Granular Activated Carbon, and the strength was found to be 96%.

[0100] The obtained activated carbon was tested according to the standard GB / T 7702.6-2008 Test Method for Methylene Blue Adsorption Value of Coal-based Granular Activated Carbon, and the methylene blue adsorption value was found to be 172.9 mg / g.

[0101] The obtained activated carbon was tested according to the standard GB / T 7702.7-2008 Test Method for Iodine Adsorption Value of Coal-based Granular Activated Carbon, and the iodine adsorption value was found to be 887 mg / g.

[0102] The obtained activated carbon was tested according to the standard GB / T 7702.15-2008 Test Method for Ash Content of Coal-based Granular Activated Carbon, and the ash content was found to be 2.4%.

[0103] The obtained activated carbon was tested according to the standard GB / T 7702.17-2008 Test Method for Flotation Rate of Coal-based Granular Activated Carbon, and the flotation rate was found to be 1.6%.

[0104] The obtained activated carbon was tested according to the standard GB / T 7702.18-2008 Test Method for Determination of Caramel Decolorization Rate of Coal-based Granular Activated Carbon. The caramel decolorization rate of Method A was found to be 99%.

[0105] The Fe content was determined according to the MT / T1068-2008 standard, and the Fe content was found to be 144 ppm.

Claims

1. A method for preparing activated carbon for low-iron, high-sugar foods, characterized in that, Includes the following steps: A. Select coking coal with a moisture content ≤1wt.%, ash content ≤10wt.%, volatile matter content 16-29wt.%, and Fe content ≤1.0wt.%, and Datong weakly caking coal with a moisture content 1.5-7.7wt.%, ash content 2.5-8.2wt.%, volatile matter content 28-35wt.%, and Fe content ≤1.0wt.%, and blend them at a mass ratio of (3-4):1, and crush them to a particle size of less than 2mm; B. Place the pulverized material from step A into a magnetic separator for magnetic separation; C. The magnetically separated material is pressed into shape using a dry roller briquetting machine; D. Crush the pressed material to a particle size of 4-10mm, and then place it in a carbonization furnace for carbonization treatment; E. Place the carbonized material in a Sleip furnace for activation treatment. Add saturated steam at 130-150℃ from the bottom of the furnace, control the furnace temperature at 750-850℃, activate for 50-60 minutes, then raise the temperature to 850-950℃, close the flue gas outlet halfway, activate for 2-3 hours, open the flue gas outlet and continue activation treatment at 850-950℃ for 10-15 hours. F. The activated material is subjected to secondary magnetic separation, acid washing, water washing, alkali washing, water washing, and drying to obtain low-iron, high-sugar food-grade activated carbon; Pickling is performed by placing the activated material in an acid solution at 60-80°C and ultrasonically vibrating it at 220-240W for 30-40 minutes. The acid solution is prepared by mixing hydrochloric acid (8-11%), sulfuric acid (20-28%), and nitric acid (7-12%) in a volume ratio of 2:2:

1. Alkaline washing involves placing the material in a 10-20% sodium hydroxide solution at 40-50℃ and ultrasonically vibrating it at 220-240W for 15-20 minutes.

2. The method for preparing activated carbon for low-iron, high-sugar foods according to claim 1, characterized in that, The magnetic field strength for magnetic separation in step B is 600-800 GS.

3. The method for preparing activated carbon for low-iron, high-sugar foods according to claim 1, characterized in that, Before magnetic separation in step B, the material is dried at 130-150℃ for 10-15 minutes.

4. The method for preparing activated carbon for low-iron, high-sugar foods according to claim 1, characterized in that, The carbonization described in step D involves first placing the material in a first carbonization furnace for preliminary carbonization for 20-30 minutes. The inlet temperature of the first carbonization furnace is 100-150℃, the heating rate is 11-12℃ / min, the outlet temperature is 300-350℃, and the rotation speed of the first carbonization furnace is 1-3 r / min. Then, the material is placed in a second carbonization furnace for deep carbonization for 2-3 hours. The inlet temperature of the second carbonization furnace is 400-450℃, the heating rate is 15-16℃ / min, the outlet temperature is 700-800℃, and the rotation speed of the second carbonization furnace is 1-3 r / min.

5. The method for preparing activated carbon for low-iron, high-sugar foods according to claim 1, characterized in that, The water washing in step F involves rinsing with 3-4 times the volume of deionized water at least 3 times.

6. The method for preparing activated carbon for low-iron, high-sugar foods according to claim 1, characterized in that, The magnetic field strength for the secondary magnetic separation in step F is 800-1000GS.