Copying partition is straightforward. Made using gparted.
Create bootable USB stick (Startup disk creator in Linux mint), boot from it. Assume we have following partitions:
boot /sdb1 (don't really know how it works) root /sdb2 home /sdb3
sudo mount /dev/sda2 /mnt ## if you have boot partition: # sudo mount /dev/sda1 /mnt/boot sudo grub-install --root-directory=/mnt /dev/sda