The introduction of coarse-grained heterogeneous solids, to be conveyed hydraulically, into hydraulic conveying systems is carried out in such a way that the solid is alternately filled in the low-pressure range into vessels filled with water and then conveyed in the high-pressure range from these into the pipe. To enable this process to be carried out without blockages, it is provided that, when the solid is filled into the vessel, a solid/water ratio of about 1:1 is set which, during discharge, is increased preferably to 1:3 by controlled addition of pressurised water. In the equipment required for carrying out the process, a proportioning device (12), associated with the solids feed, with flow and time control is provided above the vessels (1, 2) alternately connected to the pressurised water line (4) and the conveying line (3) or to the solids feed (5) and the excess water line (6), and a pressurised water line (20, 21) is introduced in the region of the upper rim (18) and of the bottom (22). <IMAGE>
