A method for producing a mixture of powder or granular state material and liquid, comprising: - producing a first mixture by conveying the powder or granular state material through an inlet hopper into an upper mixing space and by feeding the liquid into the upper mixing space, - introducing the first mixture into a lower mixing space through a conducting pipe connecting a bottom part of the upper mixing space and an upper part of a lower mixing space, the lower mixing space having a cylindrical space portion and a conical space portion, and producing a second mixture by causing it to collide into a baffle member, - discharging the second mixture through the conical space portion arranged at a bottom part of the lower mixing space, and by dividing the second mixture - discharging a first mixture portion as a mixture material, - re-circulating a second mixture portion into the upper mixing space, and - conveying a third mixture portion into the upper part of the lower mixing space, wherein the third mixture portion is introduced into the upper part of the lower mixing space in a tangential direction causing a rotational movement of the second mixture in the lower mixing space wherein the ratio of the first mixture portion and the third mixture portion is chosen to a value between 1:1 and 1:5, characterized in that - the ratio of the first mixture portion and the second mixture portion is chosen to a value between 1:1 and 1:4, and - in the lower mixing space the amount of the second mixture is adjusted so that a parabolic surface of the second mixture is - within the cylindrical space portion of the lower mixing space, including the lowest point of the parabolic surface, and is - spaced from the baffle member, and - for level measurement in the lower mixing space, pressure value is taken by means of at least one pressure gauge arranged in the sidewall of the cylindrical space portion, wherein the lowest pressure gauge is located above the conical space portion by a maximum of 150 mm. - producing a first mixture by conveying the powder or granular state material through an inlet hopper into an upper mixing space and by feeding the liquid into the upper mixing space, - introducing the first mixture into a lower mixing space through a conducting pipe connecting a bottom part of the upper mixing space and an upper part of a lower mixing space, the lower mixing space having a cylindrical space portion and a conical space portion, and producing a second mixture by causing it to collide into a baffle member, - discharging the second mixture through the conical space portion arranged at a bottom part of the lower mixing space, and by dividing the second mixture - discharging a first mixture portion as a mixture material, - re-circulating a second mixture portion into the upper mixing space, and - conveying a third mixture portion into the upper part of the lower mixing space, wherein the third mixture portion is introduced into the upper part of the lower mixing space in a tangential direction causing a rotational movement of the second mixture in the lower mixing space wherein the ratio of the first mixture portion and the third mixture portion is chosen to a value between 1:1 and 1:5, characterized in that - discharging a first mixture portion as a mixture material, - re-circulating a second mixture portion into the upper mixing space, and - conveying a third mixture portion into the upper part of the lower mixing space, wherein the third mixture portion is introduced into the upper part of the lower mixing space in a tangential direction causing a rotational movement of the second mixture in the lower mixing space wherein the ratio of the first mixture portion and the third mixture portion is chosen to a value between 1:1 and 1:5, characterized in that - the ratio of the first mixture portion and the second mixture portion is chosen to a value between 1:1 and 1:4, and - in the lower mixing space the amount of the second mixture is adjusted so that a parabolic surface of the second mixture is - within the cylindrical space portion of the lower mixing space, including the lowest point of the parabolic surface, and is - spaced from the baffle member, and - within the cylindrical space portion of the lower mixing space, including the lowest point of the parabolic surface, and is - spaced from the baffle member, and - for level measurement in the lower mixing space, pressure value is taken by means of at least one pressure gauge arranged in the sidewall of the cylindrical space portion, wherein the lowest pressure gauge is located above the conical space portion by a maximum of 150 mm.