A mineral material processing plant includes a frame; a crusher; a centrifugal conveyor; and a first conveyor; and the centrifugal conveyor includes a first idler drum and a second idler drum and a main conveyor belt surrounding the idler drums, a pivot and a folding head which is pivotable around the pivot; and the folding head includes a movable frame to which the second idler drum is bearing-mounted, to connect the centrifugal conveyor in material transport connection with the first conveyor and away from said material transport connection. A pivot point of the pivot is located in a region inside the circumference of the main conveyor belt. A method for operating a processing plant is also disclosed.