This paper presents the results of a physicochemical analysis of potassium nitrate, sodium nitrate, and humic acids obtained from mother liquors obtained from local coals. These analyses demonstrate that sodium hydroxide solution should be used to increase the extraction rate of humic acids in the extract, while potassium hydroxide solution is used to produce an effective plant growth stimulator containing valuable nutrients. The article also presents the results of analyses to determine the functional groups in the original and oxidized coals and in humic acids. The results showed that the total amount in the oxidized coal is 10.77 mg-eq/g, which is 5.26 units higher than in the original coal. The article also notes that after filtration, the resulting mass is separated into liquid and solid components. A study of the main composition of the filtrate and wash water revealed the presence of humic acids, confirming the possibility of using the wash water as a mother liquor in the production of organomineral fertilizers and other useful products. The study established all the optimal conditions and parameters for coal oxidation to produce humic acids, organomineral fertilizers, and other useful products.
Arabov et al. (Thu,) studied this question.