Fire in a deposit of metallic waste

The event occurred at a centre handling metal waste. A fire broke out in a container for aluminium alloy shavings, while handling it with a grapple excavator. The fire spread throughout the entire building.
An operator intervened with a fire extinguisher while the excavator operator, assisted by two others, removed the machine from the building. The 61 employees were evacuated.
A plume of dense smoke, visible for several kilometers, rose from the building. Ten residents were confined within the path of the smoke.

metallic cotnainer, crane

BACKGROUND INFORMATION ON THE ACTIVITIES
The company was specialised in recycling of ferrous and non-ferrous materials. On the site effected by the fire, metallic batches were sorted, consolidation and packaged for further processing/recycling.
7075 aluminium alloy (AA7075) is an aluminium alloy with zinc as the primary alloying element and composition:
zinc: 6–6.1% ,
magnesium: 2.1–2.5% ,
copper: 1.2–1.6%
[https://en.wikipedia.org/wiki/7075_aluminium_alloy].

Material damage = €2 million
Business interruption losses = €400,000.

The fire was fought by means of water and cement. The smoke triggered a request of home-confinement to few neighbouring houses.
EMERGENCY ACTIONS SEQUENCE
9:30 The fire started.
At 9:34 - Fire department was called and the shut-off valves were closed. While awaiting the arrival of emergency services, site personnel sprayed the fire with a fire hose reel and a fire hose.
10:00 - The firefighters deployed two fire hoses, one of which was mounted on an aerial ladder. 10:45 - Cement, already on site due to ongoing construction work, was used to smother the fire. A new supply had to be requested from a local provider.
12:45 - The fire was brought under control around.
From 12:45 p.m. to 16:00 - The waste was removed from the building and then sprayed with foam to ensure complete extinguishment. Atmospheric readings were taken by emergency services, and the results showed no significant impact.
16:30 - The operation concluded. The firefighting water (approximately 5 m³) was contained on site. It was analysed to determine its discharge point. The waste removed from the building was secured, and the exterior surfaces were cleaned.

Unwanted hydrogen production from oxidation of metallic waste is a well-documented occurrence. It can come to incidents, due to a combination of factors such as high humidity, long storage periods and, above all, storage in confined spaces, what enable the formation of an explosive hydrogen-air mixture.
ARIA source reports that the operator took measures aiming at improving the efficiency of the emergency actions. Nothing is said on possible preventive measures, which could be reduce the probability of formation of the explosive mixture, such as an adequate room ventilation and explosive gas detection.

Following this incident, the operator:
(1) relocated the fire hose reels.
(2) Added a 15-tonne cement stockpile to the site.
(3) Install another emergency exit within the building.