Dense phase pneumatic conveying experiment of rice husk powder and blendings of rice husk and coal was carried out at the pressure of up to 4.0 MPa in an experimental facility. Effects of operation conditions and mixing ratios of rice husk and coal on conveying behaviours were investigated. Results indicated that superficial gas velocity increased as total conveying differential pressure and supplemental gas flow rate increased, respectively. Solid loading ratio increased with increasing total conveying differential pressure, but decreased with increasing supplemental gas flow rate. Under the same operation conditions, superficial gas velocity decreased with the increasing in content of coal in blendings, while solid loading ratio increased gradually. The flow stability analysis results indicated that conveyings of blendings were more stable than that of pure rice husk, the flow stability was improved by adding coal. Characteristics of pressure drops in horizontal pipe, vertical pipe, horizontal bend and vertical bend were presented. Empirical correlations of additional pressure drop coefficients and pressure drops of vertical pipe, horizontal pipe, vertical bend and horizontal bend were proposed. (C) 2012 Elsevier B.V. All rights reserved.