Simply said : no.
Elaborate answer : Well, maybe for a short time but without too much incidences.
Even with slave bantu-speakers in southern Al-Andalus proposed by Thande, it's likely they will be arabized quite quickly.
Arabisation, as using arab not only for "administrative" purposes but as well for cultural, religious, private, familial spheres was mandatory for rising socially.
The bantu is, on other hand, maybe going to influence more southern spanish/southern andalusian arab dialects (depending on who's the ultimate winner). But seeing how little the berber influenced these OTL (while they represented the main islamic minority in Al-Andalus during all its "life" and while they had their own holdings during or after caliphate), I seriously doubt it.
Actually, we had a rapport made after the capture by Alphonse III of the Balearic Islands on their population : 42% African blacks (apparently mainly from Gao region), 32% Arabo-Berbers, 23% Metis. Depsite an abudent toponimy with many berbers and african origins, it have little legacy.
In fact, the process of arabization is likely to be accelerated if ties severed between Bantu linguistic regions and Al-Andalus. Without these, the slaves will likely being integrated even more into arabic culture, while they would be already deeply immegred within (few odds to have andalusian elites talking bantu to their slaves to make them comfortable).
To resume, I think it's improbable to have bantu-speaking slaves at a worth of mention importance (it's simply cheaper, easier and quicker to just take slaves from Christian merchants, from West African trade partners, Nile river...).
But let's admit an andalusian power does in west African coast what Arabs did in East up to Zanzibar. (Again, unlikely because more expansive while Christian push regularly in northern borders).
These black populations would be likely integrated as the OTL ones did. Maybe at the exception of a black rebellion in Al-Andalus they could hope some autonomy but :
-It would be upon arabized elites most likely for recognition
-Southern Iberia being the economic and politic core of Al-Andalus, little chance to have a strong andalusian power to allow this
-Now special answer for Thande, cause it's interesting depsite some quircks-
Easy. Muslim Spain defeats the Reconquista and continues according to all the clichés
You're calling
this easy? Really?
Seriously, that's hard to do after the fall of the Caliphate. Maybe a POD before that then? You'll have still to prevent invasions from Northern Africa.
When managed to do that, you'll have to conquer or submit *Morroco while preventing Christian invasions in te north (Les Croisades Franques d'Espagne, are a good book to see the constant effort from them to push back the borders when they can).
Finally, with sucess not that easy to reach, you'll have the issue I wanted to point : arabisation (especially with a strong, surviving caliphate) of slaves.
However West Africa eventually manages to rebel with help from Europeans who by this time have decided to go anti-slavery
Isn't there a bit of contradiction with a surviving strong Al-Andalus? It would mean no fleet able to reach this far in Africa (or even in Africa short) and we know the relative efficiency of double-front alliances at this time (Crusader States and Mongols by exemple).
For anti-slavery, I think you'll agree it would be a bit of deus ex machina, especially regarding the relative indifference of Christian world OTL before slaves in Arabo-Islamic world. In fact, with a strong Al-Andalus, western christian are propably still the main trader of slaves for Andalusians as they were up to 1100.
The Almoravids or whoever don't want to lose the source of cheap labour so they start some slave colonies in southern and eastern Africa too, possibly with help from Oman (or taking over Oman)
Wouldn't be easier and cheaper, rather then taking eastern Africa trade control, to use their own : Ghana, Mali, western Africa, as they did OTL for gold and slaves? Of course, it would mean no-bantu slaves, or at least, not in worth of mention importance.