GB 4632-1997 Method for determination of maximum intrinsic moisture in coal
Some standard content:
GB4632-1997 "Method for determination of maximum intrinsic moisture" and GB483-87 "General provisions for coal analysis test methods" This standard is revised according to the international standard IS01018-1975% hard coal - General provisions for analysis test methods, and is equivalent to S1018 atmospheric pressure method in technical content. According to the provisions of GR/T 1.1-93 and GB 483-87, this standard retains the main technical contents of GB 4632-84, modifies the relevant terms and symbols, and adds the preface to make the revised standard more reasonable. This standard replaces GB4632-84 from the date of entry into force. This standard is proposed by the Ministry of Coal Industry of the People's Republic of China. This standard is promoted by the National Coal Standardization Technical Committee. The drafting units of this standard are Beijing Coal Chemistry Research Institute of China Coal Research Institute, Dongmei Gongke Coalfield Geological Bureau Chemical Plant, Inner Mongolia Coalfield Geological Research Institute. The main drafters of this standard are Ma Zunmei and Zhang Yingxin. This standard is entrusted to Beijing Coal Chemistry Research Institute of China Coal Research Institute for interpretation. 1 Scope
National Standard of the People's Republic of China
Method for determination of maximum intrinsic moisture of coal
Determination of moisture-holding capncity of coal GB4632—1997
Generation GB 4632—84
This standard specifies the method, instrument, determination steps and result expression for the determination of maximum intrinsic moisture of coal under normal pressure. The standard is applicable to lignite, bituminous coal and anthracite. 2 Referenced Standards
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard is published, the versions shown are valid. All standards will be revised, and the parties using this standard should explore the possibility of using the latest version of the following standards. GB/T212—1996 Industrial analysis method of coal GB 474--1996 Preparation method of coal sample
GB475—1996 Method for sampling commercial coal
Method for sampling coal seam
GB 482—1995
3 Key points of the method
After the coal sample reaches saturated water absorption, most of the external moisture is removed with constant humidity paper, and the coagulation equilibrium is reached at a temperature of 30℃, a relative density of 96% and normal pressure. Then dry at 105-110℃. The maximum internal moisture is expressed as the percentage of its mass loss. 4 Reagents
4.1 Potassium sulfate crystals and saturated solutions: Mix 10 g of chemically pure potassium sulfate (HG 3-920) with 3 mL of water. 4.2 Nitrogen: purity 99.9%, oxygen content less than 100μL/L. 4.3 Desiccant: anhydrous silica gel or other desiccant. 5 Instruments and Equipment
5.1 Nitrogen-filled atmospheric pressure method maximum intrinsic moisture tester (humidifier, Figure 1); the temperature must be maintained at (30 ± 0.1) °C and can operate continuously for more than 3 days and nights.
Approved by the State Administration of Technical Supervision on April 17, 1997 and implemented on October 1, 1997
GB 4632 -1997
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1 Water tank shell, 2--humidifier wall, made of copper plate; 3--double cover, can pump in circulating water, 4--screw slurry, angle 15°~21, 5-potassium sulfate crystal and saturated penetration liquid, 6-weighing bottle; 7-plug-shaped gas circulator, made of brass: 8-media screw clamp: 9-leather pad; 10-heater, 11-temperature controller, composed of mercury contact thermometer, transistor condenser and electromagnetic reading; 12-temperature, graduated in 1/1CC; 13 weighing bottle positioning pin; 14-foam material; 15 measuring bottle bracket 16, 17-nitrogen inlet and outlet
Figure 1 Maximum intrinsic moisture tester G by nitrogen filling normal pressure method 4632--1997
5.2 Oscillator: Preset rate 240/min. Amplitude 40mm. 5.3 Nitrogen-filled drying oven. bzxZ.net
Choose one of the following two:
5.3.1 Small space drying oven: The box body is solid, with a small free space, nitrogen inlet and outlet, and equipped with automatic temperature control device, which can maintain the temperature within the range of 105~～110℃.
5.3.2 Ordinary drying oven (see Figure 2): The temperature can be controlled at 105～110℃, and a metal box with a size of 200mm×100mm×60mm is installed in the constant temperature zone. There is a tray in the box that can accommodate 6 weighing bottles. One end of the box is provided with a nitrogen inlet, which is connected to the nitrogen cylinder by a silicone tube. The inlet is covered with several layers of copper mesh to disperse the gas; the other end is provided with a small door to allow the tray to enter and exit freely and can be used as a nitrogen outlet. 1-Oven: 2-Metal box; 3-Drying tower 4-Nitrogen cylinder; 5-Silicone tube: 5-Copper mesh with a pore size of 0.25mm: 7-Metal tray; 8-Nitrogen gas outlet 19-Sample class; 10-Nitrogen person Figure 2 Nitrogen-filled drying oven
5. 4 Balance: Sensitivity 0. 1 mg.
5.5 Water bath: can maintain temperature (30+1)℃. 5.6 Vacuum pump: suction volume 1L/s
5.7 Suction filter bottle: 31..
5.8 Buchner funnel: diameter 100mm.
5.9 Conical flask: 250mL.
GB 4632—1997
5. 10 Standard sieve: one sieve with a pore size of 0.60 mm and one sieve with a pore size of 0.45 mm 5. 11 Constant cancer paper; cut the qualitative filter paper into about 10 mm×10 mm. When using, spray some water on the paper to make its moisture content about 13%~15%.
5.12 Wet box: a wooden box with a volume of about 250mm×250mm×150mm with a lid. The four sides of the box are lined with two layers of straw board paper or qualitative filter paper. When using, wet it with water, and the bottom of the box is covered with three layers of wet dot-lin paper. 5.13 Weighing bottle: a bottle with a diameter of about 50mm, a height of about 30mm, and a tight ground cover. 6 Coal sampling
According to GB482 and GB475, the collected coal samples should be placed in a closed thimble and sent to the laboratory in time. According to GB474, the coal sample should be crushed to a particle size of less than 0.2 mm. The crushing should be carried out by using a double-roll mill, a ball mill or a crusher that does not generate heat or excessive powder during the crushing process. If the coal sample is too wet, it can be spread out in a thin layer indoors to dry, but not baked or exposed to the sun. 7 Determination steps
7.1 Preparation of instruments
Place a mixture of potassium sulfate product and its saturated solution (4.1) with a thickness of 15mm~20mm at the bottom of the humidifier (5.1), and inject enough water into the water tank, then install it according to Figure 1, and start the instrument to maintain the temperature in the humidifier at (30±0.1)℃: 7.2 Pretreatment of coal sample
Take about 20g of coal sample into a dry conical bottle (5.9), and inject 100ml of water. Oscillate the bottle on an oscillator (5.2) for 30min, and then soak it in a water bath (5.5) at (30±1)℃ for 3h, shaking it several times during the process. Take out the bottle, pour the coal sample into a Buchner funnel (5.8) covered with filter paper, and filter it with a vacuum pump (5.6) until the coal sample just emerges from the water surface. Continue to rinse with water twice in the same way, about 25 ml each time. Then use a sample shovel to gently mix the coal sample, take out about 4 coal samples (the rest are wrapped with filter paper and soaked with water, and stored in a sealed container for later use), wrap them with double-layer filter paper, and put them on the upper sieve in the humidity box (5.12) with force by hand. Put two sieves in the box, the upper pore size is 0.60mm, and the lower pore size is 0.45mm. Put some constant humidity paper (5.11) on each sieve. Then mix the coal sample with the constant humidity paper, and let the coal mass fall on the lower sieve, and repeat the same operation until the coal sample falls on the dotted paper at the bottom of the box. Take out 1g to 2g of coal zinc, put it into a weighing bottle (5.13) of known mass, flatten it, and put it in a humidifier. 7.3 Humidity adjustment
Place the weighing bottle on the weighing bottle bracket in the humidifier, and position the weighing bottle with the fixing pin (just below the bell mouth of the gas circulator), and open the weighing bottle cover. Cover the humidifier and make it airtight, start the propeller, and pass nitrogen at a flow rate of 11./min for 10min, and then close the nitrogen inlet. Record the start time of humidity adjustment, and wait until the coal sample reaches humidity equilibrium. Open the humidifier cover, immediately cover the weighing bottle, take it out, wipe the weighing bottle, let it stand at room temperature for 5min, and then weigh it (accurate to 0.2ng). 7.4 Determination of moisture
7.4.1 Use a small space nitrogen-filled drying oven:
Determine the moisture content of the coal sample after constant humidity in accordance with Section 2.1.4 of GB212. 7.4.2. Use a common dry explosion box: Install the metal box in the constant temperature zone of 105~~110℃ in the coal box according to Figure 2, and pass nitrogen into the box at a flow rate of 350mL/min, then half-open the weighing bottle cap and place it on the tray in the box, so that the coal sample is dried in the nitrogen flow for 1.5h~2h. Take out the weighing bottle and cover it tightly, cool it at room temperature for 5min, then move it into the dryer and place it for 15min, weigh it (accurate to 0.2mg), and then carry out the inspection drying test with the same procedure, 30min each time, until the difference between the two adjacent masses does not exceed 1mg, or the mass begins to increase. In the latter case, the mass before the mass increase is used as the basis for calculation. 1) Weigh once every 24h of constant coagulation, and weigh once every 6h of constant humidity, until the difference between the two adjacent masses does not exceed 0.3% of the sample weight, that is, humidity balance is achieved. In order to facilitate the test, the same type of coal should be tested in the same batch. The equilibrium time for bituminous coal and anthracite generally takes 24 hours, and for tar coal 24~48 hours. 8.1 The maximum intrinsic moisture of the measured coal sample is: GB4632-1997
mz= m= × 100
Wherein: MHC——the maximum intrinsic moisture of the coal sample.%,-the mass of the weighing bottle and its cover·&
m2—the mass basis of the coal sample, weighing bottle and its cover after humidity equilibrium·8;m.——the mass of the coal sample, weighing bottle and its cover after drying.g. 8.2 The average value of the results of two repeated measurements (take the decimal place) is used as the reported value. 9. Method precision
The repeatability and reproducibility of the maximum intrinsic moisture determination are shown in the following table. Maximum intrinsic moisture, %
Repeatability limit
Reproducibility critical value
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