GB/T 4757-2025Methods for the batch-flotation testing of fine coal (English PDF)

4.1 Coal samples taken from coal cores

According to Chapter 5 of GB/T 30049-2013, the particle size of the screened product should be less than 0.5 mm (or the particle size to be introduced into the flotation process).

The coal powder (degree) should be no less than 1 kg in weight.

4.2 Coal samples taken from coal seams or production coal samples

After sieving tests according to GB/T 477, the particles with a size less than 0.5 mm (or the particle size specified in the process flow) in both the natural and crushed grades were selected.

Coal powder of flotation particle size (at least 10 kg) shall be added and mixed in with the raw coal according to its proportion, and its mass shall not be less than 10 kg.

4.3 The feed material is sourced from the flotation process at the coal preparation plant.

Sampling was performed according to the sampling method specified in Chapter 6 of GB/T 475-2008, using flotation feed without any added flotation agents, followed by filtration and drying.

Finally, the total mass shall not be less than 10 kg.

4.4 Analytical Testing and Storage

4.4.1 The following items shall be performed in accordance with the relevant provisions of GB/T 211, GB/T 212, GB/T 213 and GB/T 214 (additions may be made as needed). Analysis of (plus).

— Moisture (Mad);

— Ash Content (Ad);

— Total sulfur (St,d).

4.4.2 Conduct small sieve tests according to GB/T 477.

4.4.3 After the test coal samples are dried to an air-dry state, they should be stored in a sealed container in a dry place, and the storage time should not exceed [a certain period of time]. 10 months.

5.1 Test Equipment

Flotation machine. 1.5L volume, structural requirements as specified in Appendix A.

5.2 Test Equipment

The experimental equipment is shown in Table 1. Table 1 Test Equipment Serial Number Name Unit Quantity Specification 1 Timing device stage 1; Measurement range. 0 min ~ 10 min; Accuracy. 1 s 2 microsyringes, 0.5 mL capacity, 0.02 mL graduation.

6.1 Calculation of the mass of the test coal sample

The mass of the test coal sample is calculated according to formula (1). m= Vxrho 100-Madx 100 (1) In the formula.

m --- Mass of the coal sample used in the experiment, in grams (g);

V --- Volume of the flotation tank, in liters (L);

rho --- Pulp mass concentration, in grams per liter (g/L);

Mad --- Air-dried moisture content of the coal sample used in the experiment (%)

6.2 Calculation of Flotation Agent Dosage

When necessary, the amount of flotation agent can be converted according to formula (2) (based on dry coal slime). V= mxq rhox106 (2) In the formula.

V --- The volume of flotation reagent added, in milliliters (mL);

m --- Mass of coal sample used in the experiment, in grams (g);

q --- Unit consumption of reagent (based on dry coal slime), in grams per ton (g/t);

rho --- density of flotation reagent, in grams per cubic centimeter (g/cm3).

7.1 Test Conditions

7.1.1 Water quality. Distilled water or ion-exchanged water, or tap water may be used.

7.1.2 Slurry temperature. (20±10)°C.

7.1.3 Slurry mass concentration. (80±1) g/L.

7.1.4 Collector and its unit consumption. n-dodecane, (1000±1) g/t (based on dry coal slime).

7.1.5 Foaming agent and its unit consumption. 4-methyl-2-pentanol, (100±1) g/t (based on dry coal slime).

7.1.6 Flotation machine impeller speed. 1800 r/min.

7.1.7 Flotation machine impeller diameter. 60mm.

7.1.8 Unit air volume of flotation machine. 0.25 m3/(m2-min).

7.2 Test Procedure

7.2.1 Add water to the flotation cell to the second mark, start and adjust the flotation machine until the impeller speed and unit air volume reach the specified values, then stop the machine and turn off the valve.

Close the air inlet valve and drain all the water from the flotation cell.

7.2.2 Add water to the flotation cell to the first mark. After starting the flotation machine, add the weighed coal sample (accurate to 0.1g) to the cell and stir until the coal...

After the sample is completely wetted, add water to bring the slurry level to the second mark.

7.2.3 After stirring for 2 minutes, add the collector below the surface of the slurry. After another 1 minute, add the foaming agent below the surface of the slurry.

7.2.4 After stirring for 10 seconds, open the air inlet valve and begin skimming the foam (manual or mechanical skimming). This should be done in accordance with changes in the foam layer thickness.

Collect concentrate foam in the widened trough (do not scrape out the slurry), control the water replenishment rate, and keep the slurry level constant throughout the foam scraping process. In the later stages of foam scraping, Use a wash bottle to wash the particles from the flotation cell wall into the slurry.

7.2.5 After skimming for 3 minutes, stop skimming, close the air inlet valve and the stirring motor, and place the tailings into the basin. The tailings will settle at the bottom of the flotation cell.

Particles should be washed into the tailings basin. Particles adhering to the scraper, flotation cell lip, and cell wall should be collected into the clean coal product.

7.2.6 Add clean water to the flotation cell and start the flotation machine to stir and clean until the flotation cell is clean, then put it into a container for holding tailings.

7.2.7 After dehydrating each product separately, place them in a forced-air drying oven at a temperature not exceeding 75°C for drying. After cooling to an air-dry state, then...

Weigh and determine the ash content; if necessary, determine the sulfur content.

7.2.8 The original test records can be found in Table B.1 of Appendix B.