(a) The authority shall pay out of the proceeds from the sale of any of the bonds all expenses, including fees of agents and attorneys and other charges, which said board of directors may deem necessary or advantageous in connection with the issuance of the bonds. The proceeds of the bonds, other than refunding bonds, remaining after paying the expenses of their issuance shall be turned over to the State Treasurer and shall be carried by him in a special account to the credit of the authority and shall be subject to be drawn on by the authority solely for the purposes of acquiring real estate suitable for the purpose of the authority in Jefferson County, Alabama, including all expenses reasonably necessary in connection with such acquisition, and erecting, constructing and equipping on such real estate exhibition halls, buildings, warehouses, storage facilities, parking areas and other structures and appurtenances of every kind and character used or useful in connection with the purpose for which the authority is created and all reasonable and necessary expenses incidental thereto and to the issuance of said bonds, including payment of principal of those bonds which shall mature during the construction of said facilities and for a period not exceeding six months thereafter and including payment of interest which shall accrue on said bonds during the construction of said facilities and for a period not exceeding six months thereafter.

Any portion of the principal proceeds derived from the sale of the bonds which the board of directors of the authority may determine is not then needed for any of the purposes for which the bonds are authorized to be issued shall, on order of the authority, be invested by the State Treasurer in any securities that are direct general obligations of the United States of America or the principal of and interest on which are unconditionally and irrevocably guaranteed by the United States of America. Any such securities may, at any time and from time to time on order of the authority, be sold or otherwise converted by the State Treasurer into cash. The income derived from any such investments shall be disbursed on order of the authority for any purpose for which it may lawfully expend funds.

Any balance in said account shall, upon completion of the facilities above described and the payment of all costs, be transferred to the reserve fund account of the authority provided for in this article.

(b) The proceeds from the sale of all refunding bonds issued by the authority under this article remaining after paying the expenses of their issuance shall be turned over to the state treasurer and used only for the purpose of refunding the principal of bonds of the authority theretofore issued under this article and then outstanding and paying any premium that may be necessary to be paid in order to redeem or retire the bonds to be refunded.