DGUV Information 209-090e - Activities relating to Magnesium

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Abschnitt 1.1 - 1.1 Chips

Magnesium chips are produced during metal cutting with geometrically defined cutting edges including their dust fragments.

Particles of a mean diameter of > 500 µm are referred to as chips. These particles are not considered to be explosive when whirled up.

Magnesium flash consists of fine magnesium plates generated during die casting.

Chips are produced during dry processing of magnesium workpieces. They may ignite at high temperatures or due to friction heat.

During metal-cutting machining with water-miscible metalworking fluids (wet processing), hydrogen generation may lead to oxyhydrogen gas. In the presence of an ignition source (e. g. sparks), a hazard of explosion arises. Water-miscible metalworking fluids easily react with magnesium due to their "alkaline (basic)" properties (frequently pH value ~ 9), thereby forming hydrogen.

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Figure 2
Residues from dry processing (magnesium dusts and chips)

Chips that are wetted with water-miscible metalworking fluids also tend to self-ignite. This may result in a fire or, in the worst case, in an explosion.

During metal-cutting machining with nonwater-miscible metalworking fluids (neat cutting oils), high temperatures at the machining point may cause an oil fire. The hazard is particularly high if an insufficient quantity of MWF is supplied.

A strong atomization of the metalworking fluid may result in a flashover and a subsequent fire due to oil mist formation.

As a result of the oil fire, the magnesium chips or residues may be in danger to be ignited.