A process for roasting of metal concentrate wherein concentrate particles are fed into a roaster where they are thermally treated at a temperature in the range of 500 and 1200° C. in a fluidized bed to form a calcine. At least parts of the calcine are withdrawn from the roaster together with a gas stream as a solid fraction. Concentrate particles with a diameter at least 50% smaller than the average diameter of the concentrate particles are separated as small particles and/or particles from the gas-solid-fraction are separated in at least one step as small calcine particles and/or particles are gained in another hydrometallurgical step as other particles. Defined particles are pelletized, whereby at least 80% of the pellets feature a diameter of at least 80% of the concentrate particles average diameter. The pellets are fed into the roaster.