Alderon says Williams will continue to serve as a consultant to the mining company, which is moving ahead with its Kami mine development in western Labrador.
The $1.3-billion Kami project received federal environmental approval Tuesday.
Williams was named as a special adviser to Alderon's chairman in January 2012 and appointed two months later to the board of directors.
Alderon says Williams was an influential member of the board and played an instrumental role in the company's growth over the past two years.
He was elected premier in 2003 and stepped down from that role in 2010.
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