The invention discloses a preparation method of
humic acid, and aims to solve the problems of
high energy consumption, low extraction rate, and loss of a part of
biological activity in the traditional method. The method comprises the following steps: A, preparing an extractant, namely a mixture of
sodium carbonate,
sodium hydroxide and
sodium tripolyphosphate; B, adding a co-extraction
solvent, wherein the co-extraction agent is a mixture of
potassium hydrogen phthalate,
ethanol and
glycerol; C, adding raw materials, namely slowly adding
leonardite raw materials under agitation; D, separating, namely carrying out gravitational
settling on a
humic acid liquor in a
settling pond for 30-40 minutes to carry out
solid-liquid separation; E, aging, namely aging the separated
humic acid liquor into the tank to age for 10-12 hours, so as to adjust the pH to 5.8-7. The preparation method has the advantages that 1, the energy sources are saved, the efficiency is improved, the extraction time is shortened to 1-1.5 hours, and only 8.6kg of standard
coal and 0.74kw.h of power are required in production of each
ton of humic acid liquor according with the standard in actual running; 2, no three wastes are discharged in production.