Sources and succession of microorganisms in industrial coal flotation system

The water system in a coal preparation plant harbors a variety of microorganisms, which may pose a great effect on coal recovery, however, usually be neglected. In this study, high-throughput sequencing and the growth of indigenous microorganisms in coal slurry containing organic reagents were conducted to trace the sources and succession of the microorganisms in a running plant, and the reason for microbial community succession was deeply explained. The microbiological analysis results found that the microorganisms in the coal slurry are assigned to 34 phyla and 98 genera, all source from the coal seam. Proteobacteria, Acidobacteria, Actinobacteria, and Crenachaeota are the dominant microorganisms at the phylum level, and the abundance of Proteobacteria, Bacteroidetes, and Nitrospirae in the flotation feeding decrease, and the abundance of GAL15 increase compared to the raw coal and mine water samples. Environmental factors are important reasons for microbial community succession. Organic reagents such as collectors and frothers commonly used in coal flotation processes can change the growth environment of microorganisms. The strain QX4, isolated from raw coal and identified as Bacillus sp. can accelerate growth in coal slurry containing organic reagents. Compared with raw coal, the content of chemical oxygen demand (COD) and dissolved oxygen (DO) in the flotation feeding increase by 340 mg/l and 5 mg/l respectively, which inhibit the metabolism of Nitrospirae, Bacteroides, Proteobacteria, and Actinobacteria, while improving the metabolism of GAL15, and change the microbial community and promote the microbial succession in the coal flotation system. Therefore, indigenous microorganisms from coal seam can grow and succeed in the coal flotation system, which has a potential effect on coal flotation efficiency.