Production of humic acids from lignites and subbituminous coals by alkaline-air oxidation
The alkaline oxidation of four Spanish coals by air was studied using a two-level factorial design with four variables: temperature, time, alkali concentration and coal-to-alkali ratio. The main aim was to increase the humic acid content of these coals. The best results were obtained at the highest...
| Autores: | , , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión aceptada para publicación |
| Fecha de publicación: | 1990 |
| País: | España |
| Institución: | Consejo Superior de Investigaciones Científicas (CSIC) |
| Repositorio: | DIGITAL.CSIC. Repositorio Institucional del CSIC |
| OAI Identifier: | oai:digital.csic.es:10261/167900 |
| Acceso en línea: | http://hdl.handle.net/10261/167900 |
| Access Level: | acceso abierto |
| Palabra clave: | Lignite Subbituminous coal Oxidation |
| Sumario: | The alkaline oxidation of four Spanish coals by air was studied using a two-level factorial design with four variables: temperature, time, alkali concentration and coal-to-alkali ratio. The main aim was to increase the humic acid content of these coals. The best results were obtained at the highest temperature, longest time and lowest alkali concentration and coal-to-alkali ratio. Lower rank coals yielded the highest humic acid concentrations after oxidation, while the subbituminous coals were only slightly affected by treatment under the test conditions. A detailed study of the elemental composition of the coal and the generation of oxygen-containing functional groups is reported. The evolution of sulphur forms during the process is also described. |
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