Our investigations deal with the injection of solid products through a venturi injector into a pneumatic conveying installation. The principle of such a system and our experimental apparatus are described, Results reported here concern a large range of powder concentrations in the air-solid flow, and especially injections at high solid flow rate that have so far been poorly studied, Flow behaviours through the different singularities of the injection system are described, The influence of the particle characteristics, and especially their shape, was shown to be important. The energetic cost of product aeration and particle acceleration was estimated by calculating the pressure loss coefficient through the venturi injector and the necessary power, We finally propose a method to calculate the mixing flow parameters in the injection region using coefficients deduced from our experimental results.