Employee injured from slurry tank failure at paste plant

Background

A 200,000 litre filter tank failed at a newly commissioned paste plant. The tank was being filled with thickened tailings (slurry) for the first time.

The wall in the tank’s lower section ruptured and a section of the tank wall came away, causing significant damage to the structural components of the surrounding building.

Employees in the immediate vicinity were impacted by the slurry mass which was released. One employee suffered an eye injury from contact with the slurry.

In the image above:

1. Damaged structure:
   • displaced wall cladding
   • deformed I-beam
2. Filter tank
3. Former tank wall location (prior to failure)
4. Remnant slurry
5. Displaced tank wall

Recommended ways to control risks

To reduce the risk of plant failure, mine operators should ensure:

• suitably competent persons are engaged to design and manufacture storage tanks and confirmation is provided prior to tank commissioning that tanks are designed to withstand loading from slurry, with sufficient safety factors included
• engineering designs are independently reviewed, to ensure all potential loads and risks have been considered and addressed
• contractor management systems are robust and consider the risks associated with the construction and commissioning of plant and associated infrastructure
• safe systems of work are developed and implemented for the commissioning of tanks, including personnel exclusion zones and safe methods of inspecting vessels during commissioning testing (with water, and later with slurry)
• checks and inspections are carried out during the commissioning process to ensure components and manufacturing/assembly of the tank is in accordance with design specifications.

Legal duties

Under the Occupational Health and Safety Regulations 2017 (OHS Regulations), mine operators must:

• identify all mining hazards at their mine and assess associated risks, so far as is reasonably practicable
• implement risk controls that eliminate or reduce risks, so far as is reasonably practicable
• establish and implement a safety management system for the mine, which provides a comprehensive and integrated management system for all identified risks.

Employers and self-employed persons have specific duties to control risks associated with plant.

• Employers must provide or maintain plant or systems of work that are, so far as is reasonably practicable, safe and without risks to health.
• Employers and self-employed persons with management or control of plant must:
• identify all hazards, so far as is reasonably practicable, associated with the installation, erection, commissioning, decommissioning, dismantling and use of plant
• eliminate or reduce risks associated with plant, so far as is reasonably practicable, according to the hierarchy of control set out in Part 3.5 of the OHS Regulations
• ensure plant is inspected to the extent necessary to ensure any risks associated with the use of the plant are monitored.

Find more information

• Australian Standard 4100: Steel structures
• AS/NZS 5131: Structural steelwork - Fabrication and erection
• AS/NZS 1252.1:2016 High-strength steel fastener assemblies for structural engineering—Bolts, nuts and washers Part 1: Technical requirements