MOSCOW (Reuters) -Polymetal is considering disposing of its Russian assets in a shift to focus on its operations in Kazakhstan, the gold and silver producer said on Tuesday, sending its London-listed shares up 35%. London-listed, Russia-focused Polymetal has not been directly targeted by Western sanctions imposed on Moscow after Russia sent troops into Ukraine in February. But in common with other Russian commodity producers, it has suffered an impact as Western banks and shippers have reduced dealing with Russian companies even if they are not legally bound by sanctions law. The potential dea…