Abstract: A pneumatic pumping device for pumping liquids such as landfill leachates and polluted liquids or thick matter includes a tubular body (1) forming a pump body and defining a cylindrical main chamber (2) in the upstream and downstream ends of which respectively emerge an inlet (3) and outlet (4) for the liquid to be pumped. The pneumatic device further includes a sleeve valve (7) arranged in front of the inlet to control the passage of the liquid to be pumped through the orifice, elements (8) for controlling the opening and closure of the sleeve valve with a compressed gas, a delivery pipe (9) passing through the outlet and extending inside the tubular body over the major part of the length thereof, and elements for supplying the main chamber with compressed gas.