Method and screw spindle pump for delivering a gas/liquid mixture

A screw spindle pump for delivering a fluid which is a gas/liquid mixture, wherein the screw spindle pump has a housing which forms at least one fluid inlet and one fluid outlet and in which at least one drive spindle and at least one running spindle, coupled in terms of rotation to the latter, of the screw spindle pump are accommodated, which spindles, in each rotation position of the drive spindle, delimit together with the housing multiple pump chambers, wherein the screw spindle pump has a drive which is configured to rotate the drive spindle in a drive direction, whereby a respective one of the pump chambers that is initially open toward the respective fluid inlet is closed off, the resulting closed-off pump chamber is moved axially toward the fluid outlet and, there, upon attainment of an opening rotation angle, is opened toward the fluid outlet, wherein the screw profiles of the respective drive spindle and running spindle are selected in such a way that the mean value of the number of pump chambers per drive spindle and running spindle that are closed off both with respect to the fluid inlet and with respect to the fluid outlet is at most 1.5 over a rotation angle of the drive spindle of 360°, wherein the drive or a control device controlling the drive may be configured in such a way that, in at least one operating state of the screw spindle pump, the drive spindle is operated at least at a minimum rotational speed at which the pressure in the respective pump chamber prior to and/or upon attainment of the opening rotation angle is increased in relation to the suction pressure of the screw spindle pump, which prevails in the region of the respective fluid inlet, by at most 20% or by at most 10% of a difference in pressure between the suction pressure and the pressure in the region of the fluid outlet.