RESUMO
Se llevaron a cabo procesos de biodesulfurización de dos carbones colombianos ricos en azufre ("Mina Vieja" y "Vampiro"), en reactores de lecho empacado a nivel de erlenmeyer, utilizando un consorcio de Acidithiobacillus ferrooxidans (ATCC 23270) y Acidithiobacillus thiooxidans (ATCC 15494), evaluando la adición de cisteína a la solución lixiviante. Los ensayos fueron monitoreados por medidas de hierro en solución, pH y potencial redox. Adicionalmente, se hicieron análisis mineralógicos por difracción de rayos X (DRX) antes y después de los experimentos. Los ensayos sin adición de cisteína alcanzaron una oxidación de pirita de 45.3% y 57.9% para "Mina Vieja" y "Vampiro" respectivamente. Cuando se adicionó cisteína, la oxidación aumentó en 14.9% para "Mina Vieja" y 6.4% para "Vampiro". Por otra parte, todos los ensayos evidenciaron remoción de caolinita, debido a su interacción con el ácido sulfúrico del medio. Con base en los resultados obtenidos, los componentes del carbón influenciaron tanto crecimiento bacteriano como la eficiencia de la cisteína sobre el grado de pirita oxidada.
Biodesulphurization processes of a two sulphur-rich coals from Colombia ("Mina Vieja" y "Vampiro") were carried out at packed-bed reactors at erlenmeyer level, using a consortium of Acidithiobacillus ferrooxidans (ATCC 23270) and Acidithiobacillus thiooxidans (ATCC 15494). Cysteine addition were evaluated. The assays were monitored by measurements of iron content, pH, and redox potential. X-ray diffraction (XRD) were used to establish the mineralogy before and after the process. The assays without cysteine respectively reached a pyrite oxidation of 45.3% ("Mina Vieja") and 57.9% ("Vampiro") after 38 days. Cysteine addition improved pyrite oxidation by 14.9% ("Mina Vieja") and 6.4% ("Vampiro"). On the other hand, all the assays removed kaolinite by interaction with sulphuric acid of the media. In base to the results, coal compounds influence bacterial growth and affects the efficiency of cysteine over pyrite oxidation.
RESUMO
The mining industry is looking forward for bacterial consortia for economic extraction of copper from low-grade ores. The main objective was to determine an optimal bacterial consortium from several bacterial strains to obtain copper from the leach of chalcopyrite. The major native bacterial species involved in the bioleaching of sulphide ore (Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans, Leptospirillum ferrooxidans and Leptospirillum ferriphilum) were isolated and the assays were performed with individual bacteria and in combination with At. thiooxidans. In conclusion, it was found that the consortium integrated by At. ferrooxidans and At. thiooxidans removed 70% of copper in 35 days from the selected ore, showing significant differences with the other consortia, which removed only 35% of copper in 35 days. To validate the assays was done an escalation in columns, where the bacterial consortium achieved a higher percentage of copper extraction regarding to control.