Abstract: An apparatus for determining properties of a dust mixture flowing through a cross-sectional area of a coal dust line is provided. It has at least one sensor, which has at least one transmitting device for coupling electromagnetic and/or acoustic radiation into the dust mixture and at least one receiving device for generating a measuring signal on the basis of radiation reflected in the dust mixture or radiation transmitted by the dust mixture. Also provided is an evaluation device, which determines the property of the dust mixture on the basis of the measuring signal. The at least one transmitting device and the at least one receiving device or a measuring head are rotatably arranged at least approximately in the middle of the cross-sectional area.