A sand lift tool for use in a subterranean well can include an outer housing, an inner production tube positioned in the outer housing, and a dart received in the inner production tube. An annulus is positioned between the outer housing and the inner production tube. The dart can reciprocate in the inner production tube in response to variations in fluid flow between the annulus and an interior of the inner production tube. Another sand lift tool can include an outer housing, an inner production tube, and a sand collection annulus between the outer housing and the inner production tube. A flow area for fluid flow between the annulus and an interior of the inner production tube increases in response to an increase in a flow rate of the fluid flow.