Plant substrate and uses thereof

Claim 1

A process for the production of a porous ceramic granulate, for use as a plant substrate, with uniform pore structure, a pore size of less than 1 mm, and an inner surface area of about 180 m 2 /g, comprising mixing 45 to 80 parts by weight of clay, 0 to 50 parts by weight of an addition substance selected from the group consisting of calcite, quartz sand, dolomite, feldspar, fire clay, sepiolite and mixtures thereof, 15 to 30 parts by weight of water, 0.01 to 0.03 parts by weight of a liquefaction agent and 0.001 to 0.01 parts by weight of a surfactant, and foaming these substances in a dispersing installation under an over-pressure of 1.0 to 10 bar, by feeding compressed air at a temperature between room temperature and 95° C. and maintaining the foaming pressure until emergence from a nozzle producing strands from the foamed mixture; if desired, adding agents counteracting the liquefaction agent in order to produce a highly viscous, thixotropic, inherently stable foam suspension; shaping the foamed mixture into clay shaped bodies, and drying the clay shaped bodies at a temperature between room temperature and 200° C.; if desired, comminuting and screening the dried clay shaped bodies; returning the fines to the initial mixture; and finally firing the clay shaped bodies, or the comminuted clay shaped bodies, with selected particle-size range, at a product temperature within the clay shaped body of between 600° and 1500° C.