Evaluation of a coal biodesulfurization process (semi-continuous mode) on the pilot plant level

Abstract

The biodesulfurization process of coal from the municipality of Puerto Libertador (Córdoba, Colombia) with high-sulfur content (Spyritic = 1.03%, Sorganic = 0.9%, Ssulfates = 0.1%) was carried out in a 4,000 L stirred tank reactor. A mixed culture of A. ferrooxidans and A. thiooxidans was used. The process was configured in a discharge-charge system at room temperature with the pH controlled at 1.8±0.1, 4 mg/L of dissolved oxygen, and a coal particle size -3/4” (dp‹19.05 mm). Two residence times (D2: 8 days and D1: 4 days) were evaluated. The best results showed 59.22% of pyritic sulfur oxidation with a residence time of 4 days. These results show good expectations for a process which can be applied without having to grind the coal to a fine size. On the other hand, liquid effluents, produced during the biodesulfurization process, were neutralized to a pH of between 7.5–8.5, by adding lime. The neutralization reached removals of 100% total iron, 69.81% sulfates, and 66.09% total solids.