The introduction of the risk assessment process by the Mine Safety and Health Act directly involved workers in the review of designs and operational activities. Requirements for the issuance of permits, operation and inspection of winding devices are covered in Chapter 16 of the Regulations to the Minerals Act.
Engineering risk assessment
Identify all controls in place For each of the failure modes, all controls in place were identified. Identify any significant potential hazards For each failure mode identified, the effects of the failure were considered for any health and safety implications.
Health & Safety Risk Assessment
The format of the pro-forma used to document engineering risk assessments is shown below. The risk matrix introduced in Section 2.1 Engineering Risk Assessment can be used to estimate the level of risk.
Human error Assessment
Integrated approach to mine studies
While facilitating the subjective risk assessment, the project team discussed the potential human errors and technical limitations that had been identified during the previous investigation and assessment of the installation. As a result, the assessments of risk obtained during each mine survey take into account the control limitation identified at each site.
Discussion with original equipment manufacturers and consultation
These were then used to produce generally applicable recommendations for improvements in areas where it is likely to be practicable to achieve further risk reductions. The results presented below are those most likely to be generally applicable to small windings.
Analysis of accident and incident records
Selection of accident records
It is likely that the causal factors shown in Figure 3.1 also represent the main issues that require further investigation to help reduce the risks arising from small wind farms. The accident figures reflected in Figure 3.2 are likely to contain a greater proportion of small wind accidents and reinforce the need for a specific emphasis to be placed on behavioral safety and those factors affecting human reliability.
Small winders: single fatality accidents
RSJ stop blocks at the bottom of the shaft were not in place at the time of the accident. The main cause of the accident was the deterioration of the strength of the winding rope due to excessive abrasive wear.
Selection of study sites
A shift boss was killed in an incline shaft when the ship he was riding in derailed and he was ejected. A worker was killed when, contrary to procedures and a warning, he drove a small ship down an inclined shaft and was crushed against the hanging wall.
Regulatory aspects
The requirements for winding installations are included in Chapter 16 of the Regulation; The majority of this Chapter concerns winding machines licensed under Regulation 16.2.1, namely those used for man-winding. This would imply the need to comply with Regulation 16.25 (test of new rope) and also to regularly test rope strength.
Generic hazards
- Runaway conveyances
- Unexpected and uncontrolled conveyance movement
- Derailments
- Moving machinery and parts of machinery
- Slipping and falling from heights
- Falling objects
There was a high risk of people being crushed or knocked down by vehicles that were moving out of control. The risk of people being hit by falling objects was identified as a significant potential hazard for all vertical and steep winding systems studied.
Assessment of controls
Winder machinery
A three-winding warning device was also often used; this causes a warning signal to sound when the rising conveyor is three revolutions of the wrapping drum away from the bank. The system is also linked to the roller brakes to prevent unintended movement of the roller, and relies on a series of signals to allow the operator to release the brakes.
Ropes
OEMs noted that retractors are often moved from one installation location to another, and that insufficient research appears to have been done on retractor design as it relates to the proposed duty. On small winding installations in the production areas of the mine there is a tendency for the weekly cable inspections to be carried out by various types of competent persons.
Physical barriers and devices for arresting conveyances and other
Special interlocking safety fall rails (the "vula-vala device") are used at the head of slopes to form an "airlock" and thus prevent vehicles and material cars from entering the shaft except under proper control;. If the rails are not resting on the ground, the force on impact is likely to be sufficient to dislodge the drop rails from their anchor points;.
Conveyances and attachments
In one case, neither the mine's engineering nor operations departments considered this to be within their areas of responsibility. Therefore, they were not routinely inspected. It was noted that the operating staff was generally unaware of the importance of this issue.
Shaft and shaft equipment maintenance
Safe positioning of personnel
Physical barriers and work procedures did not adequately control the risk of such events; and. Written procedures stipulated that workers should not deliver trams or take up a work position in drop station groups due to a high risk of falling or being struck by rolling stock.
Falling from heights
The actions involved in regularly carrying out this activity put people at risk of falling into the shaft; Failure to adequately barricaded or cover the shaft increased the risk of people descending the ladders stepping into the shafts.
Operator reliability
None of the ammeters examined were marked, coded or provided with additional warning lights to indicate when critical values had been reached. For example, at one mine there had been a long-term shortage of the correct forms and the driver had been issued with a kit for a scratch game which did not contain a number of critical checks that should have been carried out on the winder he was. in operation.
Falling objects
As well as being at risk of falling from the means of transport, these people were also at risk of being hit by something falling down the shaft. While the main purpose of bank doors is to prevent the uncontrolled entry of vehicles into the shaft, they can also play an important role in preventing both people and objects from falling down the shaft.
Design of shaft and station layouts
Handling of material cars
There appear to be several general factors that affect the quality of design, maintenance and operation of small coils. Studies showed that installation, operation and maintenance standards tended to be higher in larger mines where there was a culture of licensed winding operation.
Application of regulations to small winding plants
Use of risk assessment
However, the potential level of health and safety risks found to be associated with small wind turbine operations is such that they should now be treated as a priority. This report also identifies the significant potential hazards associated with small winding systems (for both vertical and inclined applications) along with the typical control measures that were in place to reduce the risk of these hazards occurring.
Operating procedures
Training
Inspections, testing and examinations
The design of retrofit features to facilitate this, and the relevant procedures, should be considered. Many of the shortcomings identified in the study, and reported in the previous chapter, should be identified through this.
Signalling systems
These problems are caused by either failure to properly inspect and identify deficiencies, or failure to take corrective action on deficiencies once identified.
Winder design and application
Design of incline shaft layouts
Small winder risk assessments should be used as an integral part of the training process to help define training needs and standards and to ensure trainees are informed of the hazards and risks they face. The relevant sections of SABS 0293 should be used as the basis for the certification of persons responsible for carrying out visual rope examinations.
Further research and development
The regulations relating to the small winding plant need to be urgently revised to clarify the confusion that currently prevails. A safety standard for the design, installation, operation, maintenance, inspection and testing of small coils, together with their peripheral activities, should be developed to act as a technical guide and as a reference source for current best practices.
Contracted project outputs
A report containing an analysis of accidents and incidents and identifying critical problem areas in the design, maintenance and safe operation of small winders at mines together with recommendations for improvement. The analysis of past accidents and incidents, together with risk assessments of current practices, will highlight the need to review current mining practices and establish more efficient practices, thus providing a solid basis for improved operation and maintenance of small winders.
Overview of potential human error audit
If the information is inadequate or confusing, the reliability of the decision is likely to suffer. For each task element, it should be noted what feedback is required to let the operator know that he has successfully completed an action.
Summary of comments from the user workshop
Ropes • noted that small winders on the diamond mines use crosby clamps and do not splice the rope. Operations • For unauthorized retractors, a procedure should be put in place to get people back off the shaft if power is lost during the shaft survey.
Summary of OEM discussions
34;winch" as opposed to "reeler" is probably only justified on rigs where all winding operations are performed in full view of the driver. Specifications queries often lack proper specifications. This avoids the need for a "freewheel" or " driving through the brakes" for speed control.
Summary of engineering assessment findings
The design of the brake system of links and pins does not allow for lubrication of the pins. The pins show signs of wear from heavy use. structural change requires repair and maintenance bolt-on brake column poorly repaired maintenance of engineering standards inspection of connections and pins pins cannot be easily removed for inspection. especially lower jaw pins) NDT is not used on some rigs. The design of the station excavation at some of the lower stations of the shaft would drive a runaway car into the station.
Mine risk assessments
Coupling problems and damage to motors can be caused by non-standardized coupling designs due to breakage of. 6 monthly dynamic test by specialists annual NDT of critical components due to rope breakage daily inspection.
Checklist of potential control limitations
Load control maximum loads and number of material cars that can be transported at one time are not defined and. Bank doors can be left open especially on shafts with steep slopes. Warning people of risky situations.
