Preparing potassium fulvic acid based on lignite from different regions of China

China is the world’s biggest coal producer and is rich in coal resources. But lignite is one of the coal resources with a lower utilization rate and added value. How to improve its utilization rate and added value has drawn great interest among researchers. Potassium fulvic acid is successfully extracted from 29 lignites collected from different regions of the country, and treated with alkali and sulfonation. The results show that the yield of potassium fulvic acid from lignite from Xinjiang coal mines is relatively high, while from Yunnan coal mines are relatively low. After the orthogonal experiment, the order of the influencing factors of this experiment is explored as follows: potassium hydroxide>formaldehyde>temperature>sodium sulfite>time. The best process conditions are 13% potassium hydroxide, 70°C, 2 h, 6 % formaldehyde, and 17% sodium sulfite.