Mechanism and Fine Coal Beneficiation of a Pulsating Airflow Classifier

ABSTRACT

Traditional air classifiers produce binary splits based on the terminal velocity rather than the density of the feed. In this study, a pulsating air with a sine-like shape wave was introduced into a vertical column air classifier to achieve the density dominant separation on −6+3 mm fine coal. A lab-scale separation device was used to investigate the effects of pulsating characteristics (amplitude and frequency) and particles volumetric concentration on pulsating airflow separation in a batch process. The optimum operating conditions of 34.1 cm pulsation amplitude, 2.45 Hz frequency and 500 g feed amount achieved 48.08% separation efficiency, 68.22% combustible matter recovery and produced a clean coal with 17.98% ash (from a feed containing 42.02% ash), 47.73% yield and Ep value of 0.17. The results showed that the pulsating air classifier has a potential for fine coal dry beneficiation. The motion of particles in a pulsating airflow field under a hindered settling condition has been presented.

KEYWORDS:

• Dry beneficiation
• fine coal
• inertia force
• pulsating air classifier

Funding

This research was supported by the National Natural Science Foundation of China (Nos. 51404267, 51574234, 51674257) and the Fundamental Research Funds for the Central Universities (2014QNB15).

Additional information

Funding

This research was supported by the National Natural Science Foundation of China (Nos. 51404267, 51574234, 51674257) and the Fundamental Research Funds for the Central Universities (2014QNB15).