MT 79-1984 English PDFUS$279.00 · In stock
Delivery: <= 3 days. True-PDF full-copy in English will be manually translated and delivered via email. MT 79-1984: Determination Method for Dust Concentration and Dispersity Status: Obsolete
Basic dataStandard ID: MT 79-1984 (MT79-1984)Description (Translated English): Determination Method for Dust Concentration and Dispersity Sector / Industry: Coal Industry Standard Classification of Chinese Standard: C70 Word Count Estimation: 7,741 Date of Issue: 10/16/1984 Date of Implementation: 7/1/1985 Older Standard (superseded by this standard): MT 79-1984 Summary: This standard applies to the determination of workplace dust concentration in coal mines Inoue. MT79:---This is a DRAFT version for illustration, not a final translation. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.) will be manually/carefully translated upon your order.Determination Method for Dust Concentration and Dispersity Ministry of Coal Industry Standards MT 79-84 Method for determination of dust concentration and dispersion Published on October 16, 1984 1985-07-01 implemented Published by the Ministry of Coal Industry of the People's Republic of China ContentsDust concentration measurement method 1 Instruments, equipment and materials 12 Selection and arrangement of measuring points in wells3 Filter Sampling Measurement Step 3 4 Calculation of filter membrane sampling results 3 5 Quick Dust Detector Step 4 Method for determination of dust dispersion 1 Instruments, equipment and materials 4 2 Dust specimen preparation method 4 3 Determination step 5 4 Calculation of measurement results 5 Appendix A Method of Degreasing the Filter Membrane 6 Appendix B Dust Measurement Site Record Form 7 MT 79-84 Method for determination of dust concentration and dispersion Dust concentration measurement method This standard is applicable to the determination of dust concentration in coal mine shafts. 1 Instruments, equipment and materials 1.1 Analytical balance. Sensitivity 0.1 mg. 1.2 Desiccator. glass container with a diameter of 160 ~.200 mm, with color-changing silica gel inside. 1.3 Dust sampler. use the filter unit sampler qualified by the focal point designated by the Ministry of Coal, which has an explosion-proof certificate, and the rapid measurement Dust meter. 1.4 Gas flowmeter. The division value is 1 liter, and the flow rate range of the flowmeter used on the filter sampler is 15 ~ 40 liters/minute. 1.5 Filter membrane. The synthetic fiber filter membrane is used, and the retention rate of the filter membrane should be ≥95% when tested with dust with a median diameter of 0.5 microns. Stability of film weight. The weight change due to temperature changes in the atmosphere should be ≤0.1%. 1.6 Sampling head. the inner diameter of the top cover is 35 mm. 1.7 Filter clamp. The inner diameter of the clamp ring is 31 mm. 1.8 Empty box barometer. The minimum graduation of the dial is 0.5 mmHg. 1.9 Wet and dry thermometer. -26 ~ 51 ℃. 1.10 wind meter. 0.3 ~ 5m/s. 1.11 Stopwatch. ordinary stopwatch for on-site dust measurement. 1.12 Tweezers and brushes.2 Selection and arrangement of measuring points in the up and down wells2.1 The dust content in the air at each production operation site in the underground is measured once every tenth, and the surface operation site is measured once a month to evaluate the operation site Labor hygiene conditions. When new mines, new levels, new working faces are put into production, process changes or new mining technologies, new dust protection methods are put into use, the Evaluate the occurrence of dust within 5 days after work. 2.2 The general principle for selecting a dust measurement position is to arrange the measurement points in the breathing zone where the dust is spread more evenly on the return air side of the dust source. 2.3 Respiratory zone refers to the area where the working place is about 1.5 meters high from the floor of the roadway and close to the breathing of the operator. In the case, the height of the breathing zone should be changed according to the actual situation. 2.4 For the selection and arrangement of the measuring points on the up and down wells, see the table below. Dust detection point layout of production process Mining Working face 1.Gently inclined and inclined coal seam shearer falling coal shearer return air side 10 ~ 15 meters 2. Shearer driver operates the working place of the shearer driver 3.Working place of driver of hydraulic support driver 4.Pneumatic coal fall, manual coal fall and artificial coal fall One person works at 3 ~ 5 meters on its return side; multiple people work at the end One person returns to the wind side 3 ~ 5 meters. MT 79-84 (Continued) Dust detection point layout of production process Mining Working face 5.Drilling and drilling location on the working surface 3 ~ 5 meters on the return side 6.Electric coal drill drilling workers 3 ~ 5 meters from the wind return side 7. Back to the column to put the working range of the scraper conveyor operator 8.Three to five meters from the air return side of the coal-falling working face of the thin coal seam planer 9.Pulverizer driver's work place 10. Multi-process simultaneous operation of the working face 10 ~ 15 meters from the end of the working face in the return air lane 11. Work face firing After firing, the workers have entered the working surface and started to work. location. Digging Working face 1. Return air side 4 ~ 5 meters behind the heading machine operating unit 2. Driving machine driver's working place 3. Mechanical loading On the side of the roadway where the air duct is not installed, the return of 4 to 5 meters from the rock loader Merry. 4. Artificial Rock Loading On the side of the roadway where the air duct is not installed, the return air is 4 to 5 meters away from the mine car. In flow 5. The center of the roadway is 4 to 5 meters from the drilling site of the air drill and electric coal drill. 6.Drilling and rock loading machine work at the same time 7. The coupons are within the scope of operator activities 8. Withdrawable ventilation The dust spreads between the dust generation point on the working surface and the dust collector hood. Within the breathing zone of a uniform area 9. Cutting contact is within the scope of operator's activities 10. The brush is 4 to 5 meters away from the wind return side of the operation site. 11.The ceiling is 4 to 5 meters from the return air side of the operation site. 12.The bottom is 4 to 5 meters from the return air side of the operation site. 13. Work face firing After firing, the workers have entered the working surface and started to work. location. Anchor shot 1. The working location of the eye-punching workers is 5 ~ 10 meters 2. Anchor workers 5 to 10 meters from the wind return side 3.The location of the sprayer workers is 5 ~ 10 meters on the return air side. 4.Agitating and loading workers 5 to 10 meters from the return air side 5.The loading and unloading workers' working place is 5 ~ 10 meters from the return air side. Reprint point 1.The operation of scraper conveyor is 5 ~ 10 meters away from the return side of the transfer point of the two conveyors 2.Belt conveyor operation is 5 to 10 meters away from the return air side of the transfer point of the two conveyors 3.Coal (rock) point and 5 to 10 meters from the return air side of the dust source in the tank 4. Cage driver and coal worker working place of driver and coal worker 5.Working place of manual material handling staff MT 79-84 (Continued) Dust detection point layout of production process Downhole Other places 1. 3 ~ 5 meters from the wind return side of the geological groove operator 2. Maintenance workers 3 to 5 meters from the wind return side 3.Material warehouse, power distribution room, pump room, machine repair room, etc. Surface mine 1.Drilling hole drilling rig 3 ~ 5m downwind side 2. Rig driver operates the rig driver's room 3. Electric shovel operation Electric shovel operation site 4 ~ 5 meters downwind side 4. Shovel driver operates shovels driver's room Ground work Business premises Within the scope of activities of operators in surface coal bunkers, coal preparation plants, building materials plants, machine repair plants and gunpowder manufacturing plants Wait for production3 filter sampling and measurement steps3.1 Sampling filter with synthetic fiber filter.When the dust concentration at the sampling site is less than 100 mg/m3, use a plane with a diameter of 40 mm Filter, the maximum weight gain should not exceed 20 mg, when the dust concentration is greater than 100 mg/m3, use a funnel-shaped filter with a diameter of 75 mm. 3.2 The balance used in the dust measurement shall be checked once a year according to the regulations of the metrology department. 3.3 Take the tweezers on both sides of the filter membrane for sampling, place the filter membrane on the balance and weigh and record the initial weight. Membrane clips (there must be no wrinkles and no gaps between the filter membrane and the membrane clips), put them into the numbered filter box for later use. 3.4 When sampling, remove the prepared filter clip and fix it on the sampler. The dust-receiving surface of the sampler must face the wind. 3.5 For continuous dust production operations, sampling should be performed 5 minutes after production has reached normal conditions.Intermittent dust production operations should be performed by workers. When sampling. 3.6 Determine the sampling duration according to the expected value of the dust concentration at the production site at the time of sampling and the minimum value of dust on the filter membrane. But one It should generally be no less than 10 minutes, and the weight gain of the dust on the filter membrane should not be less than 1 mg.The sampling duration can be calculated according to formula (1). t = W × 1000 CQ Where. t --- sampling duration, minute; W --- the weight gain of dust, mg; C --- estimated dust concentration on the working surface, mg/m3; Q --- flow rate during sampling, l/min. 3.7 The sampling flow rate should be 15 ~ 40 liters/minute, generally 25 liters/minute is available. The flow should be kept constant during the sampling process (flow meter Should be corrected every six months). 3.8 When sampling, record according to the table in Appendix B 3.9 After sampling, take out the fixed ring of the membrane, put the dust-receiving side up, and quickly put it into the sampling box, and bring it back to the laboratory for weighing and analysis. 3.10 If the filter membrane before and after sampling is contaminated or dust is lost, it should be discarded and resampling required. 3.11 Before sampling, the filter membrane should be placed in a desiccator to avoid moisture. After sampling, the filter should be dried in a desiccator for 2 hours before weighing. After that, it is dried and weighed every 30 minutes, and the operation is repeated until the weight of the two adjacent samples does not exceed 0.1 mg. 3.12 Filter membrane degreasing. When there is oil mist in the air at the sampling site (rock lane driving). The filter membrane should be used with NY-120 solvent oil (or NY-90 Solvent oil) immerse the eluted oil and weigh again (see Appendix A).4 Calculation of filter membrane sampling resultsThe dust concentration is calculated according to formula (2). MT 79-84 C = W2-W1 Qt × 1000 In the formula. C --- dust concentration in the air, mg/m3; W2 --- filter weight after sampling, mg; W1 --- filter weight before sampling, mg; t --- sampling duration, minutes; Q --- Sampling flow, l/min.5 Quick dust detector measurement steps5.1 When using a fast dust detector, check the voltage of the battery inside the instrument. When the battery voltage is lower than the used voltage, it should be performed as required Charging. 5.2 The sampling flow rate and sampling time of the instrument should be corrected and adjusted according to the instrument's instructions. 5.3 The sampling start time is the same as specified in Article 3.5. 5.4 When measuring dust, the air inlet of the instrument must face the wind. 5.5 When measuring dust, continuously measure data of not less than three at each measuring point. Take its average value. Method for determination of dust dispersion This standard is applicable to the determination of dust dispersion in coal mine shafts. 1 Instruments, equipment and materials 1.1 Biological microscope. The magnification is 600 ~ 675 times. 1.2 Objective micrometer. The division value is 0.01 mm. 1.3 Eyepiece micrometer. Ruler eyepiece micrometer graduation value is 0.1 mm; mesh eyepiece micrometer graduation value is 0.2 mm. 1.4 Butyl acetate. HGB 3289-60 analytical grade. 1.5 Magnetic crucible. 25 ml. 1.6 Glass slide. 75 × 25 (mm). 1.7 Cover slip. 25 × 25 (mm). 1.8 Glass straws. 5 ml volume. 1.9 Blood cell classification counter. The counting range is 0 ~ 9999. The above equipment must be cleaned before use to avoid dust pollution.2 Preparation method of dust specimen2.1 The samples required to determine the degree of dust dispersion were sampled using the filter sampling method. 2.2 Specific operations 2.2.1 Place the collected dust filter in a magnetic crucible or small beaker. 2.2.2 Add 1 ~ 2 ml of butyl acetate to the magnetic crucible with a glass pipette. Stir thoroughly with a glass rod to dissolve the filter and suspend Even. 2.2.3 Use a glass dropper to pick up the suspension that has been dissolved and suspended uniformly, and add a drop to the dried glass slide. Flatten the glass slide Shake several times to disperse the droplets. Then slide the slide with another glass slide. After one minute, a layer of dust appears on the glass slide film. 2.2.4 Attach a label indicating the specimen number and sampling date. 2.2.5 Keep specimens in glass dishes to avoid contamination by external dust. And prepare for microscopy, if you find that there are too many dust particles, you can add Butyl acetate was diluted and the specimens were prepared again. MT 79-84 Each of the above operations should try to avoid contamination by external dust.3 Measurement steps3.1 Calibration of eyepiece micrometer. Use the objective micrometer to calibrate the length of each scale of the eyepiece micrometer, and observe the objective micrometer and The number of divisions between the two lines where the two scales of the eyepiece micrometer coincide, and the actual length represented by each division of the eyepiece micrometer is calculated. 3.2 Specimen determination. Place the specimen on the microscope stage and fix it with a tablet, so that the graduation line of the eyepiece micrometer is tangent to one end of the dust particles, Observe that the dust particles occupy the grid of the eyepiece micrometer, and measure the size of the dust particles. During the microscopy, you should measure them one by one without order, and move the sample Under the condition that the direction is not changed, the long diameter is met with the long diameter and the short diameter is met with the short diameter. 3.3 Counting of specimens. When measuring the degree of dust dispersion, each specimen needs to measure more than.200 grains. When counting, use a blood cell classification counter to arrange them in bins. If a dust of 2 microns or less is detected, press the first gear once. A dust > 2 ~ 5 microns, that is, once in the second stage, And so on.4 Calculation of measurement resultsWhen measuring the degree of dust dispersion, statistics are made according to four levels. ≤ 2 microns, > 2 to 5 microns, > 5 to 10 microns, and > 10 microns. The grid is as follows. Dust particle size (micron) ≤2 > 2 ~ 5 > 5 ~ 10 > 10 Remarks Number of particles (grain) percentage(%) MT 79-84Appendix AFilter membrane degreasing method A.1 Principle. Use NY-120 solvent oil (or NY-90 solvent oil) to dissolve the motor oil attached to the sampling filter to eliminate sampling The oil quality of the filter is increased. A.2 Distillation of NY-120 Solvent Oil A.2.1 Items and equipment required. NY-120 solvent oil, condenser tube (spherical or serpentine with a length greater than 400 mm), 1000 ml distillation flask, 200 ℃ thermometer, 500ml reagent bottle, adjustable electric furnace (300 ~ 1500 ℃), universal cross clamp, titration stand, 260mm aluminum pan, diameter 8mm hose, paraffin, cup holder, adjustable control clip. A.2.2 Distillation method. Put NY-120 solvent oil in a distillation flask. Install a.200 ° C thermometer and place the distillation flask with paraffin. In the aluminum pan, the condensing tube was connected, and the power was finally connected to make the solvent oil boil. At this time, the solvent oil was distilled out. Collect with cleaning reagent bottles Set spare. Distillation is stopped when the temperature of the solvent oil boiling exceeds 120 ° C (the distillation process can be omitted when NY-90 solvent oil is used). A.3 Filter membrane degreasing A.3.1 Equipment required. Three weighing bottles (50 mm in diameter); one elbow hemostatic pliers, one electroplated steel tweezers, two glass plates, one stopwatch. A.3.2 Operation method A.3.2.1 Take three weighing bottles and number them, and pour in distilled NY-120 solvent oil or NY-90 solvent oil. A.3.2.2 Use tweezers and hemostatic forceps to fold the filter with oil in half three times, and then use the elbow hemostatic forceps to clamp the folded filter edge Tighten, shake in the weighing bottle with solvent oil No. 1 and No. 2 for 2 minutes each. A.3.2.3 Put the degreasing filter on a clean glass plate, and use tweezers to open the filter and let the degreasing agent evaporate for 30 minutes and weigh. A.3.2.4 Perform the second deoiling of the first deoiled filter membrane in the No. 3 bottle according to the method described above. If the weighing result is decreasing, it should be Perform degreasing and weighing. Until it does not decrease. The dust and oil concentration on the filter membrane are calculated as follows. Concentration of oily dust (mg/m3) = Filter weight after sampling-Filter weight before sampling (mg) Flow (l/min) × time (min) × 1000 Dust concentration (mg/m3) = Filter weight after degreasing-filter weight before sampling (mg) Flow (l/min) × time (min) × 1000 Oil concentration (mg/m3) = oily dust concentration-dust concentration MT 79-84Appendix BDust measurement site record form Dust measurement date. Instrument model. Dust measurement location and operation team Dust type and operation process Filter number Sampling time (minutes) Flowmeter reading (L/min) Dust concentration (mg/m3) Dust prevention measures Additional information. This standard is proposed by the Technology Development Department of the Ministry of Coal Industry. This standard was drafted by the Chongqing Research Institute of Coal Science Research Institute. The main drafter of this standard is Zhang Wenxin. 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