Coal Dust Consolidation Using Calcium Carbonate Precipitation Induced by Treatment with Mixed Cultures of Urease-Producing Bacteria

Abstract

To promote the application of microbially induced mineralization technology in the field of coal dust suppression, two urease-producing bacteria were co-cultured, with the aim to define the influence of different culture conditions on the growth and urease activity of the bacteria. According to the results, when S. pasteurii and B. cereus CS1 were inoculated in succession at a volume ratio of 1:1 and an interval of 14 h, the mixed bacteria achieved optimal growth and had the highest urease activity; when the initial pH value of culture medium was 9 and the urea and Ca2+ concentrations in the substrate were uniformly 0.1 mol/L, the growth and urease activity of the mixed bacterial culture reached their peaks. SEM-EDS and XRD results indicated that, regardless of the specific urease-producing bacteria used (single urease-producing bacteria or the mixed urease-producing bacteria), their mineralization products were uniformly vaterite-type and calcite-type calcium carbonate; FTIR and thermogravimetric analysis also confirmed their mineralization products as calcium carbonate. By spraying the bacterial inoculants with a corresponding calcium source and urea on pulverized coal, it was found that the bacteria successfully survived and caused pulverized coal to be consolidated. In particular, the mixed bacterial inoculant manifested a stronger consolidation effect, with a wind erosion–induced mass loss of less than 20 g/(m2•h). We provide experimental support for the field of microbial coal dust suppression.