There is nothing in OHS legislation that covers the dismissal (or 'sacking') of an employee. Warnings and dismissals are covered under the Fair Work Act and these are also usually covered in the award or Enterprise Bargaining Agreement.
The OHS Act places a clear duty on employees (section 25), but this is very much dependent on the employer having complied with his/her duties (section 21) - most importantly to provide such information, training and supervision.
If someone breaches their duties under the Act then, depending on the severity, WorkSafe may prosecute. It's not often that workers are prosecuted, mainly because often there's a breach on the employer side.
However, if an employee were to intentionally not comply with an OHS requirement, then the employer can take the matter up through the agreed or legislated (industrial) procedures - that is, a series of warnings (with a final written warning) which can then lead to dismissal if the matter is not remediated by the employee. Employees have a duty under employment law to follow any legal and reasonable request of the employer. So it's the same situation as, for example, an employee who is always late - he/she can't/shouldn't be dismissed immediately, but must be given the chance to remedy the problem. If this doesn't happen, then the employer has the right, after having followed the correct procedure, to dismiss him/her.
The exception is when an employee does something very serious, and it's intentional: basically this is gross misconduct (eg fighting, stealing, sabotage). If the gross misconduct is related to an ohs matter, then the same rules apply - the worker can be dismissed immediately (but like any other dismissal, the employee has the right to take the matter up as an 'unfair' dismissal if he/she believes there was any unfairness).
In cases where there may be such a situation, then WorkSafe may, in fact, also prosecute - but it would most likely be under a different section of the Act - Section 32, which places a duty (on ANYONE) to not 'grossly endanger' the health or safety of anyone at the workplace.