Backflow cascade novel process for producing lithium-7 isotope

A method for producing lithium-7 isotope which comprises the following steps:

• (1) continuously and countercurrently running an aqueous phase and an organic phase;
• wherein the organic phase sequentially passes through an upper backflow section, an extraction section, an enrichment section, and a lower backflow section circularly,
• and
• wherein the aqueous phase sequentially flows through the lower backflow section, the enrichment section, the extraction section and the upper backflow section, and then flows out;
• (2) adding a lower backflow phase-conversion liquid into the lower backflow section;
• adding an upper backflow phase-conversion liquid into the upper backflow section;
• and
• adding a reverse extraction liquid into the product acquiring section;
• (3) adding a feed liquid comprising lithium-7 into the enrichment section, said feed liquid being extracted by the extraction section and the upper backflow section, and enriched in the enrichment section, wherein the organic phase from the enrichment section is separated into two parts:
• (a) one part flowing into the product acquiring section for reverse extraction, thus obtaining an enriched product comprising the lithium-7 isotope;
• and
• (b) the other part flowing into the lower backflow section.