"The “phenomenal” world, said Kant, is not real: reality, as perceived by man’s mind, is a distortion. The distorting mechanism is man’s conceptual faculty: man’s basic concepts (such as time, space, existence) are not derived from experience or reality, but come from an automatic system of filters in his consciousness (labeled “categories” and “forms of perception”) which impose their own design on his perception of the external world and make him incapable of perceiving it in any manner other than the one in which he does perceive it. This proves, said Kant, that man’s concepts are only a delusion, but a collective delusion which no one has the power to escape. Thus reason and science are “limited,” said Kant; they are valid only so long as they deal with this world, with a permanent, pre-determined collective delusion (and thus the criterion of reason’s validity was switched from the objective to the collective), but they are impotent to deal with the fundamental, metaphysical issues of existence, which belong to the “noumenal” world. The “noumenal” world is unknowable; it is the world of “real” reality, “superior” truth and “things in themselves” or “things as they are”—which means: things as they are not perceived by man."
This excerpt contains many misrepresentations of Kant's breakdown of the human mind, as Kant wrote in "The Critique of Pure Reason". Kant argued that the human mind, specifically, the phenomena, must process concepts and precepts via The Concepts of The Understanding(12 of them) in the construct of Space and Time. The notions of Space and Time, are not things outside of us, but they are part of our intuition. When objects are presented outside of us, in them of themselves, humans process these objects and they gain knowledge and understanding from their experiences. Those experiences are defined by Concepts, things that exist prior to our understanding of them via our senses, and our precepts, things that come from our experiences via our senses.
No where does Kant in his writings state that these concepts, as they are processed in our mind via Space and Time, are not "real". He argues that they are "real", as they are called phenomena. Phenomena are "tangible" objects in Space and Time, via our senses, pushed through the concepts of the understanding, which allows our minds to gain knowledge.
The noumenal world is not a "separate" world per se. These are concepts that can not be placed in the phenomena world, things that are filtered via Space and Time. Yes, they are "things as they are", but they are much more abstract concepts: e.g Freedom, Soul, God, and the like. Can these concepts be processed via Space and Time, and projected into our minds? Answer: No.
In short, this is one example of Rand's mis representation of Kant's positions.