Gail,
PRONI has this document and accompanying information in it’s e-catalogue: (D4576 dated 1866 – 1984)
“Papers of the Blackstaff Spinning and Weaving Mill, Springfield Road, Belfast containing accounts, minutes, articles of association and shareholder information. Also in the collection are various documents relating to The Lurgan Weaving Company, Co Armagh, Doagh Flax Spinning Company, Co Antrim and J & W Charley and Co Ltd of Dunmurry, Co Antrim.
The linen trade played a pivotal role in the social and economic development of Belfast. The manufacture of linen was the catalyst that allowed it to grow from a town into the region's major city. Demand for linen products soared after 1865 due to the effects of the cotton embargo's placed upon the Confederate states during the American Civil War.
Cotton and linen spinning mills and weaving factories were established in North and West Belfast with Blackstaff, Conway Mill, Oldpark, Whitehouse, Greencastle, Mossley etc giving employment to large numbers of people.
In 1863 there was 23 Linen Manufactures listed in the Belfast Street Directories, by 1870, there was 150. Something in the region of 21,000 workers were employed in the Linen trade at its peak. . By the end of the 19th century Belfast was the linen capital of the world”.
A link on this site gives a little information about the mill:
http://www.belfastforum.co.uk/index.php?topic=13260.0
You could try Ballyclare Historical Society to see if they have any old photos (their website mentions having a collection of film, video and sound tapes).:
http://www.ballyclarehistoricalsociety.co.uk