The application of combined lignite cleaning processes, bacterial leaching and flotation, for reducing higher ash and sulfur contents

ABSTRACT

In this study, biological and physicochemical processes were combined to decrease the ash and sulfur contents of finely ground coal. Firstly, biodesulphurization experiments of lignites with high ash and sulfur contents were carried out with air-supply fiberglass bioreactor using Acidithiobacillus ferrooxidans. At the end of the 12-hour bacterial desulfurization experiments; ash content, sulfur content, calorific value, sulfur emission value, recovery of calorific value, and combustible recovery values were 33.88%, 3.97%, 3982 kcal/kg, 0.24% 91.22%, and 89.74%, respectively. Afterward, in the second stage experiments, flotation method was used to beneficiation Can/Canakkale lignites by physicochemical methods. In flotation experiments, the effects of collector (Fuel oil; 0–900 g/t) and frother (MIBC; 0–300 g/t) dosages on flotation were investigated. Optimum collector and frother dosages were determined as 750 g/t and 250 g/t in flotation experiments, respectively. In flotation experiments under optimum conditions ash content, sulfur content, calorific value, sulfur emission value, recovery of calorific value and combustible recovery values were 16.38%, 0.75%, 5166 kcal/kg, 0.03% 98.60%, and 96.11%, respectively. As a result of all experiments, ash and sulfur removal efficiencies were carried out 65.12% and 86.93% in Can/Canakkale lignites, respectively.

KEYWORDS:

• Lignite
• clean coal technology
• biodesulfurization
• flotation
• acidithiobacillus ferrooxidans

Acknowledgments

The author sincerely thanks the managements of Turkish Coal Enterprises, Directorate of Çan Lignites Enterprise in Çanakkale for their help in providing the necessary samples and author also gratefully General Directorate of Mineral Research and Exploration for providing all laboratory facilities.