What is a mobile processing unit (MPU)?

What is a mobile processing unit (MPU)?

Mobile processing units (MPUs) are purpose-built vehicles that are used in mining operations to manufacture or blend Class 1 bulk explosives at the location of blasting.

The MPU delivers the explosive directly into the blast hole via a pump or auger. Apart from minor residues, the vehicle is not intended to transport the manufactured product.

The Dangerous Goods Safety (Explosives) Regulations 2007 defines a MPU as follows:

“A mobile processing unit (or MPU) means a vehicle or a moveable piece of equipment (also called a mobile mixing unit or MMU) designed to transport the constituents of a bulk ammonium nitrate-based explosive to the place where the explosive will be manufactured and used”.

Ammonium nitrate (AN) emulsions, suspensions and gels (UN 3375 mixtures) are transferred at the mine into MPUs for blending with various sensitisers to convert the UN 3375 mixture into Class 1 explosives.  Most commonly the mixture is converted in the blast hole.

MPUs are not permitted to transport Class 1 explosives on public roads.

Explosives manufacture (MPU) licence

An explosives manufacture (MPU) licence is required by the prime contractor who transports a constituent of an ammonium nitrate-based explosive in an MPU on a road or a mine.

Information on the safe transport of explosives on roads and at mines is available from:

Transport of explosives on roads and at mines - guidance note - 165 Kb

This guidance note assists in identifying the regulatory requirements for the transport of explosives in Western Australia on both public roads and mine sites.

Transport of explosives in underground mines - information sheet - 53 Kb

This document sets out the critical issues to consider and how they should be approached. Further information on explosives transport on mines is available in Resources Safety’s Transport of explosives on roads and at mines - guidance note.

Legislative requirements

A road vehicle that operates under an explosives manufacture (MPU) licence is not required to be separately licensed to transport dangerous goods.

Vehicles must comply with the Australian Explosives Industry and Safety Group (AEISG) code of practice for mobile processing units regarding their design, construction, operation, safety equipment and placarding.

The Mobile processing units code of practice is available from the Australian Explosives Industry and Safety Group (AEISG).