METHOD OF PREPARING HUMIC SUBSTANCES Russian patent published in 2001 - IPC

FIELD: coal-processing industry and agriculture. SUBSTANCE: brown coal with moisture content of at least 20% crushed to particle size of less than 2 mm is mixed with solid alkali at ratio per 1 kg of dry ash-free weight of coal and 14.2-15.3 moles of NaON or 15.9-16.1 moles of KOH, mixture is kept at room temperature for 0.9-1 h till complete dissolution of alkali in moisture of coal, then dried and heat treated at 130-150 C for 4-7 h, and humic substances are subsequently extracted with water at 95-100 C. EFFECT: increased yield of humates to 83-86.9% of dry ash-free weight of coal. 2 ex, 3 tbl