The state of roof bolting

By Ntsako Khosa

Roof bolting is of paramount importance to preserve both human lives and the reputation of the mining company. We look at the current state of roof bolting in underground mines.

Continued efforts are being made to make mining safer. Efforts were increased after over 600 deaths were reported in 1994. In 2015, the South African mining industry experienced the lowest rate of deaths at 77. Mineral Resources Minister Mosebenzi Zwane said the improvement is encouraging and the industry is moving in the right direction towards its “Zero Harm” objectives. 

 

Mining accidents and fatalities

Many reasons are to blame for deaths that occur in mines, and the incorrect application of roof bolts is one of them. “Since January 2016, various failures regarding the correct application of roof bolts have been found at South African mines, mainly in gold and platinum mines. In some of these instances, these failures led to accidents that caused deaths of (and injuries to) mineworkers. In all of these instances it led to the issuing of work stoppage instructions, issued by the inspectors of the DMR by virtue of section 54 of the Mine Health and Safety Act,” says Paul Mardon, head of occupational health and safety at trade union Solidarity. According to Mardon, insufficient support, poor supervision and fall of ground (FOG) are linked to insufficient roof bolting and have contributed to accidents and/or section 54 instructions in the national mining industry in the past year. Insufficient support contributed 31%, poor supervision 19%, and FOG 23%.

Accidents and fatalities cause mines to lose millions in revenue because work stoppages take place, resulting in the closure of the entire mine for a week or a month. A report by the Chamber of Mines of South Africa estimates that the application of safety stoppages — known as section 54s in terms of the Mine Health and Safety Act 1996 (MHSA) — cost the industry R4.84-billion in lost revenue in 2015.

Mardon says, “Incorrect or insufficient roof bolting is part of the bigger problem in South African mines due to insufficient support. In this regard, some of the most common failures to adhering to standards and inefficiencies have been found.”

 

Preventative measures

The mining industry often states that FOGs are inevitable due to the unpredictability of seismic events. “Although seismic events are extremely difficult to forecast and prevent, there are things that could be done to prevent, or at least reduce and mitigate them,” says Mardon. Preventative measures aren’t unknown as some of them are applied; these include netting, bolting and safety procedures. However, Mardon explains that these measures are not always applied correctly, “Incorrect application of measures are due to various reasons, such as complacency, production pressures, fatigue, as well as lack of concentration due to personal or other distractions.”

Mardon suggests that the reasons for not adhering to and applying necessary measures need to be addressed through the following: regular on-the-job-training and discussions to motivate workers to adhere to these measures; regular, effective and sincere visible felt leadership (VFL) interactions with members, where the correct and consistent adherence to these measures are addressed and encouraged; the correct emphasis of leadership on all levels — especially the supervisory level — on the correct and consistent adherence to these measures; leading by example — not telling workers to adhere to these measure while reprimanding them for time spent on the measures and focussing on production requirements; and supervisors must conduct regular PTOs (planned task observations). The Chamber of Mines has a MOSH (Mining Occupational Safety and Health) programme whereby leading practices are identified inter alia with regard to bolting and netting. As it is a voluntarily process, it is unfortunate that not all mines make use of these leading practices.

The application of good fatigue management of workers to prevent distracting them from adherence to these measures, ensuring constant supervision over workers by reliable supervisors, and introducing programmes to ensure that employees’ behaviour, conduct and attitude towards safety in mines are addressed effectively, will go a long way in addressing the issues.

The mining industry has come together to design machinery that make the installation of roof bolts efficient and safe. The latest technology or up to date machinery shouldn’t be the focus of enhancing safety in the mines. Personnel need to play an active role in ensuring the continuous safety of all. Zero Harm can be achieved when staff and the machines have a mutual relationship.


Various failures regarding the correct application of roof bolts have been found at South African mines, mainly in gold and platinum mines.


 

 

Inefficiencies in roof bolting have included the following:

  • Roof bolt supports and roof bolts protruding more than the allowed distance.
  • Protruding roof bolts were not replaced, especially after blasting occurred.
  • Bad hanging-walls were marked but not treated.
  • Roof bolts were not adequately replaced.
  • Additional support was not installed or, where installed, installations were found not to be up to standard, for example, it was not properly grouted.
  • Roof bolt support was measured 3.1m from the face after a blast instead of 2.5m as per the standard of the mine concerned.
  • Support, including roof bolts, was missing or not installed where needed.
  • Distance between support sticks was measured to be more than 1.5m in the access ways, and the stope and support sticks were not installed on solid ground.
  • Missing roof bolts on slips.
  • Brows were not adequately supported as per the standard or as per the recommendations of the rock engineer.
  • Bolts were measured 3.0m from the sidewall against a standard of 1.0m and a protruding bolt at 0.4m was not replaced.
  • Safety nets were not installed throughout the entire length of the panels.
  • Rock drill operators (RDO) were drilling under an unsupported roof, as the mechanical props measured 1.55 meters from the face.
  • Cut and damaged roof bolts were not replaced.
  • Some employees blatantly ignored direct instructions from their supervisors to stop drilling until support was installed as per the standard.

Source: Solidarity

 

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