Extraction of humic acid from coal mine tailings and piles

The long-term use of chemical fertilizers has some negative effects. However, extracting fertilizers from lignite mine waste and waste heaps has many advantages. These include the efficient use of resources, mitigation of environmental contamination, improvement of agricultural yields, economic development, and the betterment of food security. This study focused on the isolation of humic acid and the comprehensive evaluation of its chemical and physical properties. Results indicated that the optimal pH for humic acid formation was 7.5, or slightly alkaline. The composition contains essential mineral nutrients required for plant growth, including nitrogen (0.32%), phosphorus (0.50%), potassium (0.18%), calcium (53.4%), and magnesium (25.8%). The biologically active component, humic acid, exhibited high efficacy, meeting the standard requirement with an active substance content of 35%. The yield and quality of wheat increased significantly to 2190 kg/ha due to humic acid, which shows its effectiveness. Hence, using coal mine tailings and piles for humic acid production diminishes environmental pollution and augments soil fertility and crop yields.