Article 32 of the Brazilian flag law says, "Flags in a bad state of repair
should be delivered to any military unit to be incinerated on Flag Day [19
November] according to the special ceremonial procedure." The Armed Forces
Regulation on Honors, Salutes, Signs of Respect, and
Military Ceremonial, 8 August 2000, sets out this ceremonial procedure in article 162:
The flags to be incinerated are deposited on a pyre or in a metal
receptacle located near the flag pole where the Flag Day flag-hoisting
ceremony is to take place [a special ceremonial raising of the flag at noon
before the assembled troops], and soaked with alcohol.
The commander directs the reading of the Order of the Day, setting out the
significance of the day and of the ceremonies.
After the reading, a party consisting of the oldest member of the unit and
the best turned-out set fire to the flags.
The flags having been incinerated, the ceremony proceeds with the singing
of the "Hymn to the Flag." In the navy, the singing is preceded by a 21-gun
salute.
The ashes are placed in an urn and buried at an appropriate location on
the military post or cast into the sea in the case of a ship.
Apparently, state military police units (which are sort a like a
gendarmerie, but under state rather than federal authority) also conduct
this ceremony.