Is the Mind [essentially] bound to ignorance "not-knowing" or free?

What do you mean by "bound to ignorance"?

If here by 'being bound' you mean a default state to which it will inevitably revert to, a default state of being ignorant, then that is one thing. If you mean that the starting configuration is the default which can be non-reversably modified, that is another thing.

I don't know which of the two is closer to the meaning of your question.

When i started out in my profession i sucked at it, there was ignorance which was more or less replaced by acquired knowledge and this replacing resulted in profits.

I think it is all-around evident that mind is one thing and ignorance is another thing.

If they were bound as in conjoined then overcoming ignorance would not be possible.

Your using the word "essentially" reminded me of Tibetan doctrine -- for example What is the Mind? By His Holiness the Dalai Lama.

I highlighted bits which I think address your question.

Buddhist literature, both sutra and tantra, contains extensive discussions on mind and its nature. Tantra, in particular, discusses the various levels of subtlety of mind and consciousness. The sutras do not talk much about the relationship between the various states of mind and their corresponding physiological states. Tantric literature, on the other hand, is replete with references to the various subtleties of the levels of consciousness and their relationship to such physiological states as the vital energy centers within the body, the energy channels, the energies that flow within these and so on. The tantras also explain how, by manipulating the various physiological factors through specific meditative yogic practices, one can effect various states of consciousness.

According to tantra, the ultimate nature of mind is essentially pure. This pristine nature is technically called "clear light." The various afflictive emotions such as desire, hatred and jealousy are products of conditioning. They are not intrinsic qualities of the mind because the mind can be cleansed of them. When this clear light nature of mind is veiled or inhibited from expressing its true essence by the conditioning of the afflictive emotions and thoughts, the person is said to be caught in the cycle of existence, samsara. But when, by applying appropriate meditative techniques and practices, the individual is able to fully experience this clear light nature of mind free from the influence and conditioning of the afflictive states, he or she is on the way to true liberation and full enlightenment.

Hence, from the Buddhist point of view, both bondage and true freedom depend on the varying states of this clear light mind, and the resultant state that meditators try to attain through the application of various meditative techniques is one in which this ultimate nature of mind fully manifests all its positive potential, enlightenment, or Buddhahood. An understanding of the clear light mind therefore becomes crucial in the context of spiritual endeavor.

In general, the mind can be defined as an entity that has the nature of mere experience, that is, "clarity and knowing." It is the knowing nature, or agency, that is called mind, and this is non-material. But within the category of mind there are also gross levels, such as our sensory perceptions, which cannot function or even come into being without depending on physical organs like our senses. And within the category of the sixth consciousness, the mental consciousness, there are various divisions, or types of mental consciousness that are heavily dependent upon the physiological basis, our brain, for their arising. These types of mind cannot be understood in isolation from their physiological bases.

Now a crucial question arises: [etc.]

That says that afflictive emotions are states of mind but are not intrinsic qualities of the mind.

I think in other words that means that the mind is not "essentially bound" to them.

Also it says explicitly that meditation etc. are "of use" -- i.e. to cleanse the mind of conditioned afflictions.

It also mentions that the nature of the mind is "knowing" -- not "ignorance".

Speaking of "afflictive emotions", "ignorance" is considered to be one of the afflictive emotions -- both in Tibetan Buddhism, and according to the Pali and so on.

If it is free, the meditation and other means enjoined for the sake of liberation are of no use.

I'm not sure I understand the question, to me it sounds like a specious argument i.e. a bit like saying, "Is the body essentially sick, or essentially healthy? In either case medicine and other requisites are useless, because they're either ineffective (impossible) or unnecessary." -- which reminds me of the Brahmana Sutta (SN 51.15) again.

Don't get infatuated with the word "essence" and "essential". Some people talk about "the essence of the mind" and try to make the mind the ultimate reality. What matters is that the mind is the chief of sukha or dukkha -- bad births and good births -- like in the Dhammapada:

1. Mind precedes all mental states. Mind is their chief; they are all mind-wrought. If with an impure mind a person speaks or acts suffering follows him like the wheel that follows the foot of the ox.
2. Mind precedes all mental states. Mind is their chief; they are all mind-wrought. If with a pure mind a person speaks or acts happiness follows him like his never-departing shadow.

And you still have to "do" the non-bright and non-dark karma, to get fully enlightened.

All this means is that you do have to work on your mind, on your actions through speech, body and thoughts -- to get a good births and/or be fully enlightened -- (not doing rituals or clinging to sensual objects).

Is the Mind [essentially] bound to ignorance "not-knowing" or free? If it is bound, then its essential nature of "non-knowing" cannot depart, and, therefore, liberation is not [possible, or] if the essential nature departed, the mind would cease to be a Mind, i,e. it can no longer not-know.

There's no issue here since the premise was wrong to begin with. Yes, to unenlightened beings, the mind is pretty much bound to ignorance, but it has nothing to do with the "essential nature" of things here. The only inherent/essential nature of conditioned phenomena is the Three Marks: Anicca, Dukkha, and Anatta. And since it's exactly because of Anicca, even Ignorance and Dukkha are not permanent, hence there's always the possibility for total final liberation to take place, if one so chooses.