In municipalities of more than 500,000 population the provisions of Division 10 of this Article 8 shall apply to and govern the purchase of supplies.
The provisions of this Section are subject to any contrary provisions contained in "An Act concerning the use of Illinois mined coal in certain plants and institutions", filed July 13, 1937, as heretofore and hereafter amended.
65 ILCS 5/8-9-2