I don't see slavery being abolished in the CSA, just contained to certain industries; mostly agriculture--though only certain crops--manual labor, and service. Poor whites are going to raise hell if the planters try to expand "nigger work" into the industrial and/or commercial sectors.
White workers at the Tredegar Iron Company went on strike for this very reason in 1847. The strike failed and Tredegar replaced the strikers with even more slave workers.
Here's an example; let's say that there are two steelworks outside of Birmingham, one manned by whites, the other manned by slaves being rented to the owner. We could very well see white unions try to exert pressure on the slave-drivers to toss out the blacks so the industry isn't "spoiled" and that factory work stays "respectable" by keeping it whites-only.
That's far more likely to get the owner of the "white" steel mill to fire his workers and replace them with slaves who can't form unions or go on strike.
Good points, but I have heard the case of ending CSA slavery argued many times and some state that it may not end until the 1920s if only for economic reasons b/c it was during that time that mass produced farm equitment was capable of replacing manual labor in OTL.
Mechanical cotton pickers only became capable of replacing manual labor in the 1950s, not the 1920s. And as Wolfpaw points out, slaves were also a status symbol.