Coal Preparation » General
This report provides detailed information on coal flotation with oscillatory air supply at pilot scale.
At the start of the project, the effectiveness of three different devices (named A, B and C) for converting steady airflow to oscillatory airflow was evaluated. It was found that devices A and B could reliably generate the oscillatory airflow with the desired oscillation frequency. In contrast, device C could not be used to generate oscillatory airflow reliably owing to the difficulty of operation.
pilot-scale coal flotation tests were conducted using a 17-cm diameter column with two different spargers: one made from a perforated plate and the other made from a porous plate. The oscillatory airflow was generated by installing device A in the air intake line. Improvement of flotation yield was achievable with oscillatory air supply for both spargers tested, but the sparger made from the perforated plate gave much greater improvement than the other sparger. Further testing for maintenance requirements found that the sparger made of the perforated plate also outperformed the other sparger.
The key technical barrier for future site trials has been identified to be the scaling up of the device for generating oscillatory airflow at large air flowrates. Despite its effectiveness at pilot scale, Device A cannot be used at large air flowrates. Device B is promising and after further development it can be tested in a full-scale flotation operation.
The air sparging system comprising Device B and the perforated plate sparger has the advantages of ease of installation, low operation cost, and low maintenance requirement.