An old dog is never too old to learn something new. NOTE: This clarification was made in the 2021 edition of NFPA 499.
In NFPA 499, the definition of a Class II, Div 1 HAZLOC is as follows: (emphasis by me)
5.1.3.1 Class II, Division 1
A Class II, Division 1 location is a location:
(1) In which combustible dust is in the air under normal operating conditions in quantities sufficient to produce explosive or ignitible mixtures, or
(2) Where mechanical failure or abnormal operation of machinery or equipment might cause such explosive or ignitible mixtures to be produced, and might also provide a source of ignition through simultaneous failure of electrical equipment, through operation of protection devices, or from other causes, or
(3) In which Group E combustible dusts may be present in quantities sufficient to be hazardous in normal or abnormal operating conditions.
This essentially states that there are no division 2 locations when dealing with Metal Dusts (Group E).
In the 2017 edition of NFPA 499, this is how this was worded:
5.1.3.1 Class II, Division 1. A Class II, Division 1 location is a location
(1) In which combustible dust is in the air under normal operating conditions in quantities sufficient to produce explosive or ignitible mixtures, or
(2) Where mechanical failure or abnormal operation of machinery or equipment might cause such explosive or ignitible mixtures to be produced, and might also provide a source of ignition through simultaneous failure of electrical equipment, through operation of protection devices, or from other causes, or
(3) In which Group E combustible dusts may be present in quantities sufficient to be hazardous.
[70:500.5(C)(1)]