MT/T 746-1997Technical condition for compound fertilizer of humic acids from coal (English PDF)

4.1 Appearance

Visual identification.

4.2 Determination of Humic Acid Yield

4.2.1 Method summary

Extract the humic acid from the sample with sodium pyrophosphate lye, precipitate the humic acid with excess inorganic acid, weigh the precipitate, and add to correct.

4.2.2 Reagents

4.2.2.1 Hydrochloric acid (GB

622). 5% (V/V) solution.

4.2.2.2 Sodium pyrophosphate alkaline extraction solution. Weigh 15g of chemically pure sodium pyrophosphate (Na4P2O7 · 10H2O) (HG3-1288) and 7g of chemically pure sodium hydroxide (GB 629) dissolved in 1L of distilled water and kept tightly closed.

4.2.3 Equipment

4.2.3.1 Analytical balance. Sensitivity 0.0001g.

4.2.3.2 Constant temperature water bath.

4.2.3.3 Constant temperature drying oven. The temperature can be controlled at 110 °C ± 5 °C.

4.2.3.4 Centrifuge. The minimum speed is.2000r/min, and the volume of the centrifuge cup is greater than 150mL.

4.2.3.5 Muffle furnace.

4.2.3.6 Quantitative filter paper (blue ribbon).

4.2.3.7 Weighing bottle with ground stopper. 50mm in diameter and 30mm in height.

4.2.4 Measurement steps

4.2.4.1 Extraction

Weigh about 1g of the analytical sample with a particle size of less than 0.2mm (accurate to 0.0002g), put it in a 250mL Erlenmeyer flask A, and add sodium pyrophosphate alkaline extraction solution 100 mL, shake well, cover a small funnel at the mouth of the conical flask, put it in a water bath at 100 °C ± 1 °C (when the temperature is not reached, adjust with an appropriate amount of glycerin), heat and extract 2 h (shake every 0.5h), take it out, cool to room temperature, transfer it all into a centrifuge cup, and centrifuge at.2000r/min for 30min, Decant the solution into another 500mL Erlenmeyer flask B, wash the insolubles twice with.200mL of water, and centrifuge after each wash.

Collect all the washing liquid into Erlenmeyer flask B.

4.2.4.2 Precipitation

Transfer the conical flask B solution to a 500mL volumetric flask, add water to the mark, shake well, take.200mL of the solution into a beaker, and add 20mL of hydrochloric acid (4.2.2.1) Humic acid was allowed to settle, the suspension was centrifuged, and the supernatant was decanted.

4.2.4.3 Weighing

Dry the quantitative filter paper and weighing bottle in a drying box at 105 °C ~ 110 °C to constant weight in advance, and filter the humus obtained by 4.2.4.2 with filter paper.

For acid precipitation, move the filter paper with precipitation to a weighing bottle, dry it in a drying box at 105 °C ~ 110 °C for 2h, take it out, and cool it in a dryer to Weigh at room temperature (about 20min). Repeat drying, cooling and weighing until the difference between two consecutive weighings is less than 0.001g, and calculate the humic acid precipitation Mass of the sediment (m1).

4.2.4.4 Burn

Put the humic acid precipitate together with filter paper into a porcelain crucible of known quality, first ash at low temperature (200 °C ~ 250 °C), and then at 600 Burn in a muffle furnace at °C ± 25 °C for 1h ~ 2h, take out the crucible, cool it in the air for 5min, then put it in a desiccator to cool to room temperature and weigh.

Repeat the burning, cooling and weighing until the difference between two consecutive weighings is less than 0.001g, and calculate the mass (m2) of the burning residue.

4.2.5 Expression of results

6.1 Packaging

Products are packed in woven bags lined with polyethylene film bags.

6.2 Signs

The following signs should be noted on the product packaging. product name, trademark, humic acid yield, nitrogen, phosphorus, and potassium content (special fertilizers only indicate nitrogen Total amount of phosphorus and potassium; if products made from chloride-based fertilizers should indicate chlorine content), net weight, this standard number, production license number, production plant Name, factory address.

6.3 Transportation

The product should be protected from moisture, sun and rupture during transportation.

6.4 Storage

The product should be stored in a cool and dry place.