Installation for conversion of paper residue into a mineral product, comprising a fluidized bed device with a wind box and a distribution plate above said wind box for an evenly distributed supply of at least combustion air to bed material of the fluidized bed above the distribution plate and to paper residue that is introduced into the fluidized bed device comprising a control system for controlling the amount of bed material above the distribution plate and the size of said bed material particles, which control system is arranged to monitor and maintain a process parameter within a predefined range, which process parameter is related to the amount of combustion air, characterized in that A1. the control system is arranged to control the temperature of the combustion air in the wind box within a range of said process parameter that is selected at a predefined target value of said temperature plus and minus 25° Celsius, preferably plus and minus 15° Celsius, wherein A2. the control system is further embodied such that the target value of the temperature of the combustion air in the wind box expressed in centigrades is defined by the equation Ttarget= -500 * calorific value + 1400, wherein the calorific value expressed in MJ/kg relates to the paper residue including any additional matter that is introduced into the fluidized bed device, and/or B1. the control system is arranged to control the amount of combustion air supplied to the wind box at a predefined target value plus and minus 15% for each square meter area of the distribution plate, wherein B2. the control system is further embodied such that the target value of the amount of the combustion air Qtarget that is supplied to the wind box for each square meter of the distribution plate is defined by the equation Qtarget= 4.35 * organic fraction, wherein the organic fraction relates to the percentage organic material forming part of the paper residue that is introduced into the fluidized bed device, and/or B3. the control system is further embodied such that the target value of the amount of combustion air supplied to the wind box for each square meter area of the distribution plate is set at a level of 1.7 m3/s for each square meter area of the distribution plate. A1. the control system is arranged to control the temperature of the combustion air in the wind box within a range of said process parameter that is selected at a predefined target value of said temperature plus and minus 25° Celsius, preferably plus and minus 15° Celsius, wherein A2. the control system is further embodied such that the target value of the temperature of the combustion air in the wind box expressed in centigrades is defined by the equation Ttarget= -500 * calorific value + 1400, wherein the calorific value expressed in MJ/kg relates to the paper residue including any additional matter that is introduced into the fluidized bed device, B1. the control system is arranged to control the amount of combustion air supplied to the wind box at a predefined target value plus and minus 15% for each square meter area of the distribution plate, wherein B2. the control system is further embodied such that the target value of the amount of the combustion air Qtarget that is supplied to the wind box for each square meter of the distribution plate is defined by the equation Qtarget= 4.35 * organic fraction, wherein the organic fraction relates to the percentage organic material forming part of the paper residue that is introduced into the fluidized bed device, and/or B3. the control system is further embodied such that the target value of the amount of combustion air supplied to the wind box for each square meter area of the distribution plate is set at a level of 1.7 m3/s for each square meter area of the distribution plate.