It was in March last year that the lifts were tested positively.
Igor Son has previously been convicted of doping and was suspended for seven months for a misdemeanor in 2015.
According to the Kazakhstan Weightlifting Federation, Son will not lose his Olympic medal after his positive doping test was left in an out-of-competition test and six months after competing internationally.
Kazakh weightlifting has had major problems with doping and was stripped of Olympic medals in 2008, 2012 and 2016.