User blog comment:Gon10/Kuchiki Byakuya´s Bankai/@comment-10961564-20130620172314/@comment-11051098-20130623125526

You can see that his Zanpakutô apparently disintegrated as he walked away from Ichigo after asking him to protect Soul Society. The question is if it disintegrated because Byakuya was on the edge of death, or because it might have been severely damaged.