We are a sand foundry casting magnesium for the aerospace industry. However, we have recently had a number of small fires from sparks generated from the rare metal nugget inclusions which are larger than expected. Can anyone advise as to how we can fettle/ cut off with this inclusion? we currently fettle dry, however any small spark is creating a fire. This is not an area of my expertise, and this is a new casting to us. Any advice would be great, so i can write my risk assessment and look at other controls to put in place. Many Thanks

More information description required.

Is this activity done manually? 

Is there an possibility of doing the operation in an enclosure with an inert gas blanket of nitrogen or at least reduced oxygen content below combustion support levels?

Can the castings etc be subject to some form of NDT - x-ray etc to identify the inclusions in the metal?

How 'bad' are the fires? Do they have credible potential to get out of hand etc - in which case some form of rapid fire suppression might be needed - if the issue is buring metal, fire solutions may be unconventional as metal based fires can be difficult to deal with - Class D fires. Dry powder is possibly the required method.

As ever without more detailed/specific information only general opinion can be given.