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Outline
During the acid in-situ leaching of uranium, sulfuric acid readily reacts with calcite to form calcium sulfate precipitate and release CO2, which causes pore blockage and permeability reduction in the ore-bearing layer, thereby hindering the efficient and green extraction of uranium resources. To reveal the reaction characteristics and blockage mechanism of calcite in acid in-situ leaching, single-factor immersion experiments were conducted under varying acidity, particle size, and solid mass to liquid volume ratios. The variations of pH, saturation index (SI), and concentrations of Ca2+ and during the reaction were analyzed, dissolution kinetics were examined based on the shrinking core model, and the microscopic morphology and phase composition of minerals before and after the reaction were investigated by SEM-EDS and XRD. The results show that the reaction between calcium carbonate and sulfuric acid exhibits distinct stages. In the system, pH generally increases, Ca2+ concentration initially rises and then declines before stabilizing, while
concentration continuously decreases and then stabilizes. Increased acidity and reduced particle size both enhance the early-stage reaction intensity and prompt the system to reach CaSO4 supersaturation earlier, thereby intensifying precipitate formation and blockage effects.A higher solid mass to liquid volume ratio increases the risk of supersaturation in the system. Kinetic fitting indicates that the reaction process better conforms to the internal diffusion control model. Microscopic characterization reveals that a flaky calcium sulfate precipitate layer forms on the mineral surface after the reaction, corroborating the above chemical analysis results. The findings provide a theoretical basis for blockage risk identification and process optimization in acid in-situ leaching of uranium.
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| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |
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