Provided are a burner such as a concentrate burner, a calcine burner, or a matte burner, or a burner using a mixture of these for feeding reaction gas and fine solids into a reaction shaft of a suspension smelting furnace, and a fine solids feeding apparatus for a burner such as a concentrate burner, a calcine burner, or a matte burner, or a burner using a mixture of these. The fine solids feeding apparatus comprises gas outlets in a fine solids discharge channel upstream of a downstream outlet end of the fine solids discharge channel. The gas outlets comprise spiral path guiding members configured to facilitate gas to flow from the gas outlets in a spiral flow path around a center axis A of the fine solids discharge channel.