PURPOSE: To capture and recover effectively liquid or solid fine particles of an alkali metal such as Na, K and its compounds from a fluid carrying them by using columns packed with particulate materials of metal and/or ceramic etc.

CONSTITUTION: More than one columns 1AW1D packed with particulate materials being used, a fluid PF carrying liquid or solid particles of an alkali metal and its compounds is introduced through an inlet 4 of the column 1A, which is kept at a temperature below m.p. of the alkali metal to be captured, to have the fine particles captured on surfaces of the particulate materials. Next, a packed column, e.g., the column 1B, wherein the captured material reaches a maximum, is heated up sequentially to a temperature above m.p. of the alkali metal to have the liquid alkali metal LA discharged through an outlet 6. Then, a solution LF, such as water, which is able to dissolve the alkali metal compounds, is injected through an inlet 7 to the packed column 1C to take out remaining metal compounds. Finally, the packed column 1D is dried by introducing a drying fluid DF.