Abstract: A hot melt composition including 100 parts by weight of a styrene thermoplastic elastomer having an intrinsic viscosity [&eegr;] of not less than 1 dl/g and 200 to 3000 parts by weight of a liquid softener selected from process oil, liquid rubber and a modified substance thereof, wherein: (a) the composition has a softening point measured by ring and ball softening pint method of from 120 to 230° C.; (b) the composition generates no crack when not less than 75% of a compressive strain is applied under an atmosphere of a temperature of −30 to 40° C.; and (c) the composition does not flow when it is allowed to stand in a load-free state under an atmosphere of a temperature of 100° C. for 24 hours.

Abstract: Proposed is an improvement in a multi-stage solvent extraction process of a metal value such as rare earth elements from an acidic feed solution containing the metal value in the form of a water-soluble salt by bringing the aqueous solution into contact with a water-immiscible organic extractant solution containing an extractant compound which releases an acid when combined with the metal ions.