When were slaves freed at Tannehill Iron works in Alabama?

....The industrial center at Tannehill kept up a fierce momentum. Trees on the hillsides were felled to be made into charcoal that fed the huge blast furnaces. Roupes Creek and a mighty steam engine powered the blowing machines to heat the fires that melted ore to be formed into "pigs" of iron which, in turn, formed the tools of war for the Confederacy. At the height of production Tannehill could turn out 22 tons of iron a day. The iron was cast into ordnance, skillets, pots and ovens for the Southern armyAt the height of production Tannehill could turn out 22 tons of iron a day. The iron was cast into ordnance, skillets, pots and ovens for the Southern army. On March 31, 1865, it all ended in fire and destruction. Three companies of the Eighth Iowa Cavalry swept through the area as a part of Union General James H. Wilson's raid on Alabama war industry sites. Smoke rose from the charred remains of the ironworks and cabins that housed 500 workers. At day's end the furnaces were no longer operational, and the foundry, tannery, gristmill, and tax-in-kind warehouse were in ruins. Source: http://www.tannehill.org/tsphist.html