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Coal Inspectorate | Alert | No.410 V 1 | 03 June 2022

Use of liquid nitrogen in the mining industry

What happened?

On Tuesday 17th May, a worker received serious cryogenic burns after immersing their hands in a container of liquid nitrogen whilst trying to shrink a brass bush for inserting into an excavator boom arm. Whilst this incident did not occur on a mine site, this type of work may be conducted on mine sites, and in many cases may be done by contractors. Regardless of who conducts the work, the Mine Safety and Health Management System must manage the risks associated with the safe use and handling of liquid nitrogen or similar substances, if it is used at the mine.

How did it happen?

Work Health and Safety Queensland inspectors reported that the worker was not wearing the correct personal protective equipment for the task. Further details related to the incident are not available at this time

Key issues

Liquid Nitrogen

Liquid nitrogen is one of the cryogenic liquids commonly used in the mining industry. As “cryogenic” means related to very low temperature, it is an extremely cold material. Liquid nitrogen has a boiling point of negative – 195.8 degrees centigrade and can expand to a very large volume of gas.

The vapor of liquid nitrogen can rapidly freeze skin tissue and eye fluid, resulting in cold burns, frostbite, and permanent hand and eye damage, even by brief exposure.

Liquid nitrogen expands 695 times in volume when it vaporises and has no warning properties such as odour or colour. Hence, if sufficient liquid nitrogen is vaporised to reduce the oxygen percentage to below 19.5%, there is a risk of oxygen deficiency which may cause unconsciousness. Death may result if oxygen deficiency is extreme. To prevent asphyxiation hazards, handlers must make sure that the work area is well ventilated.

Without adequate venting or pressure-relief devices on the containers, enormous pressures can build upon evaporation. Users must make sure that liquid nitrogen is never contained in a closed system. Use a pressure relief vessel or a venting lid to protect against pressure build-up.

Handling Safety Practices

Eye / Face Protection

Skin Protection

  • Suitably rated, loose-fitting thermal insulated or leather gloves, aprons, long sleeve shirts, and trousers without cuffs should be worn while handling liquid nitrogen. Safety shoes are also recommended while handling containers. Gloves should be loose-fitting, so they are able to be quickly removed if liquid nitrogen is spilled on them. Insulated gloves are not made to permit the hands to be put into liquid nitrogen. They typically only provide short-term protection from accidental contact with the liquid.

Recommendations

Site Senior Executives (SSEs) must:

Identify if liquid nitrogen or other cryogenic substances are used or likely to be used on the mine site. Consideration should be given to the use of alternative engineering solutions.

Where liquid nitrogen or other cryogenic substances are to be used on site:

Supervisors must:

Coal mine workers must:

Investigations are ongoing and further information may be published as it becomes available. The information in this publication is what is known at the time of writing.

We issue Safety Notices to draw attention to the occurrence of a serious incident, raise awareness of risks, and prompt assessment of your existing controls.

Authorised by Peter Newman - Chief Inspector – Coal

Contact: Anthony Logan, Senior Inspector of Mines , +61 7 3199 8013

Issued by Resources Safety & Health Queensland

Safety: This information is issued to promote safety through experience. It is not to be taken as a statement of law and must not be construed to waive or modify any legal obligation.
Placement: Place this announcement on noticeboards and ensure all relevant people in your organisation receive a copy.

All information on this page (Use of liquid nitrogen in the mining industry - https://www.rshq.qld.gov.au/safety-notices/mines/use-of-liquid-nitrogen-in-the-mining-industry) is correct as of time of printing (8 July 2022 2:33 am).