This disclosure will describe a novel finding and make the claim for the first time on a group of old compounds and formulated new compounds. These compounds have superconducting property at high temperatures, i.e., 151 K or higher. Several compounds were prepared, though not well-purified, at around middle of 1900s. Their chemical, structural, electric and magnetic properties were studied and reported but their superconducting property has not been known and has never been exploited because the idea of type-II superconductivity was not proposed at that time. The experiments to further verify their high temperature superconductivity require the utilization of sophisticated facilities on synthesizing highly pure compounds and the deregulation from government security authorities on purchasing the starting materials.

The present invention relates to use of an amino-containing neutral phosphine extractant of Formula I in extraction and separation of thorium, and a process of extracting and separating thorium using the amino-containing neutral phosphine extractant of Formula I, ##STR00001##
wherein, R.sub.1 and R.sub.2 are each independently selected from the group consisting of C.sub.1-C.sub.12 alkyl, R.sub.3 and R.sub.4 are each independently selected from the group consisting of C.sub.1-16 alkyl and hydrogen, and n is an integer of 1 to 8.

The present invention relates to use of an amino-containing neutral phosphine extractant of Formula I in extraction and separation of thorium, and a process of extracting and separating thorium using the amino-containing neutral phosphine extractant of Formula I, ##STR00001##
wherein, R.sub.1 and R.sub.2 are each independently selected from the group consisting of C.sub.1-C.sub.12 alkyl, R.sub.3 and R.sub.4 are each independently selected from the group consisting of C.sub.1-16 alkyl and hydrogen, and n is an integer of 1 to 8.

The present disclosure relates to processes for recovering rare earth elements from an aluminum-bearing material. The processes can comprise leaching the aluminum-bearing material with an acid so as to obtain a leachate comprising at least one aluminum ion, at least one iron ion, at least one rare earth element, and a solid, and separating the leachate from the solid. The processes can also comprise substantially selectively removing at least one of the at least one aluminum ion and the at least one iron ion from the leachate and optionally obtaining a precipitate. The processes can also comprise substantially selectively removing the at least one rare earth element from the leachate and/or the precipitate.

The present disclosure relates to processes for recovering rare earth elements from an aluminum-bearing material. The processes can comprise leaching the aluminum-bearing material with an acid so as to obtain a leachate comprising at least one aluminum ion, at least one iron ion, at least one rare earth element, and a solid, and separating the leachate from the solid. The processes can also comprise substantially selectively removing at least one of the at least one aluminum ion and the at least one iron ion from the leachate and optionally obtaining a precipitate. The processes can also comprise substantially selectively removing the at least one rare earth element from the leachate and/or the precipitate.