How can we treat "an angry employee in addition to owning an aggressive mood permanently"?

Anger henders reason which is usually have a negative impact on the business. If you really want to kepp such an employee send him/her on an anger control traininag programs.

Identify his / her strengths, align that with the job description / role and ignite that for returns. 

Igniting the strengths will use the aggression constructively and results / returns will suppress the anger and convert it into pleasure of self achievement and job satisfaction.

I would suggest putting them to a anger management course after you have given them an opportunity to change their attitude and a verbal warning.

To contain any angry employee first thing to do is to figure out the reason behind the anger, Asking what is the problem and how to be helpful seem to cool things off. Getting to the root of the issue and resolving it on the spot should do and it will give employees satisfaction that the company/management cares. Of course this scenario is in case the matter was work related.

Anger is a force that can move an organization forward to improve, or, it can be a force that destroys the organization's ability to fulfil it's purpose on an everyday level. Managers play a critical role in determining which of these results will come about.

Angry employees have big EGO and when its hurted they get angry, we have a staff if someones points out her mistakes she lashes out in anger.

to such employees things need to be handled with care as if we fuel anger more it will be process which will continue and effect eveyone's work.

if we can tackle anger by keeping them busy, being friendly and understanding their issues they can be tamed and will loose anger ...hopefully