Mine monitoring or control (Part 1) – What is the objective?

Ray Ballantyne

07 Dec 2023 · 2000 words, 8 min read

A discussion regarding mine control rooms

Introduction

A mine is a process and, particularly in underground operations, can be a complex process.

The term ‘mine control’ has become widely used for situations where a mine has a staffed control room. Mine control room capabilities vary considerably but are typically supported by a range of forms of technology.

If we accept that mining is a process then let us look at how we can control that process.

The National Institute of Standards and Technology [NIST] Handbook describes 'process control' as:

the active changing of the process based on the results of process monitoring. Once the process monitoring tools have detected an out-of-control situation, the person responsible for the process makes a change to bring the process back into control.

This definition clearly implies that ‘process control’ has a dependence upon ‘process monitoring’. Therefore to achieve 'mine control’ there is a prerequisite that ‘mine monitoring’ be in place.

A number of mining companies (e.g. this job ad from South32) describe the discipline as:

Mine Monitoring and Control (MMC)

thus acknowledging that monitoring is essential to achieve control.

An anecdote from a reasonably large gold/copper mine

On this particular shift the Processing Plant Control desk was staffed by a plant operator, ‘Stewie’, as part of their regular practice of continuously rotating each plant operator through turns in the control centre.

The plant was well instrumented with SCADA/DCS systems and video, and could be fully controlled from the control centre.

An incident occurred whereby the rake in the tailings thickener tank started tearing itself to pieces. Stewie observed this happening and radioed the Supervisor. The Supervisor did not respond.

The rake continued to destroy itself.

I asked Stewie what his action would be and his only response was that he had already called the Supervisor.

I questioned him further about taking action and he wasn’t prepared to do anything without direction from his supervisor even though he had full capability to shut down the thickener.

The rake continued to destruct.

Even though Stewie was located in the control centre and was manning the plant control desk he was not doing ‘control’.

How do we do monitoring?

There is a nirvana situation where all monitoring is carried out automatically using electronic technology and data is digitally transmitted to a central repository in real time.

Most of the products that purport to do monitoring are very focused upon the use of technology. These range from handheld devices for manual entry, vehicle mounted tablets, location technology and interfaces to onboard condition monitoring capabilities including payload.

Unfortunately, in most underground mines blasting occurs regularly, generally in confined spaces. This makes the use of technology, particularly communications infrastructure, extremely difficult to implement and sustain. Timeliness of data is compromised being limited to whenever the recording device or vehicle is within communication range. In the case of many implementations of handheld devices at underground sites, data only reaches a server at end of shift when operators return, with their devices, to the surface.

Over the last 30+ years the use of voice radio systems in underground mines has developed and is now quite commonplace. Most sites will keep voice communications up toward active mining faces but are limited by the offset required to avoid blast damage. Resourcing with radio technicians is another major constraint.

Regardless of the level of automated data capture and digital transmission there is almost inevitably a component that requires human voice radio where an underground operator makes voice radio calls to the mine control room and vice versa.

The analogy of air traffic control is frequently used in relation to mine control. Pilots fly planes but work in conjunction with controllers located in a control tower. The controllers have access to a much wider (big picture) range of information than each of the individual pilots and can make decisions on a different basis. Controllers inform and direct the pilots who still fly their planes.

Many control rooms for underground mines operate largely on the basis of voice radio calls to transmit the monitoring information, which is then manually entered to a computer system.

Information communicated by voice radio to a mine control room can include:

location of personnel (this is commonly achieved by associating personnel with equipment)
location of mobile equipment
activity of equipment and personnel at a location (including stoppages and interruptions)
measures of work completed by equipment and/or personnel at a location
location (heading) status changes and environmental measurement
maintenance events relating to mobile equipment.

Consider a simple example:

An underground jumbo has a hydraulic failure.
The Jumbo operator moves to the nearest radio coverage and calls mine control to report the failure.
Mine control acknowledge the call and enter the stoppage into the computer system. Depending on the system and digital communications coverage, the stoppage may be displayed in relevant locations or on supervisor’s tablets.
The jumbo operator then calls either the operations or maintenance supervisor, possibly both, to report the failure and await assistance.

In this case the mine control role is monitoring only.

In cases where digital communications coverage throughout the mine is widespread much of this information monitoring can occur automatically or by the use of field devices (e.g. tablets) located either in equipment or handheld.

Such automatic monitoring does occur, particularly with fixed plant equipment, e.g. fans, underground crushers, hoists, seismic alarms, lightning detection, video, etc.

A number of the automatic monitoring systems trigger alarms to which control room personnel are expected to respond. There are other media by which information reaches a control room, e.g.

email
phone
paper plans
conversations with visitor to mine control
video
other computer systems such as maintenance management, mine planning, scheduling.

Mine control in its 'monitoring’ role becomes a hub of operational information.

Unfortunately many so called 'mine control’ installations, particularly those that are heavily dependent upon voice communication, stop at monitoring and reduce the role of the mine controller to that of a tally clerk.

It should be noted that mine control should be limited to information that is related to mine operations information. Too often clerical and administrative tasks are assigned to the controllers.

Implementing the control process

In developing our vision of mine monitoring and control let us revisit the NIST definition of 'process control’.

The previous section is a discussion of how monitoring can occur to support control. The NIST definition also identifies the place of the person responsible to carry out changes that deliver control of the process.

Quoting further from NIST:

Two types of intervention are possible – one is based on engineering judgment and the other is automated:

1. Out-of-control Action Plans (OCAPS) detail the action to be taken once an out-of-control situation is detected. A specific flowchart, that leads the process engineer through the corrective procedure, may be provided for each unique process.
2. Advanced Process Control Loops are automated changes to the process that are programmed to correct for the size of the out-of-control measurement.

Item 1 (OCAPS) refers to human intervention where Item 2 is in regard to automated system decision making. A common example for Item 2 is in open pit dispatch systems. This is where the dispatch algorithm is constantly reassessing the optimal assignment for each truck and providing instructions to the operator, or in the case of autonomy, directly to the truck itself.

For this discussion the focus is upon Item 1, OCAPS, where there is human intervention which can be at multiple levels including:

Control room operator (controller)
Operations supervisor
Engineer/geologist
Maintenance supervisor
Safety/emergency teams.

Here is a template for how a controller reacts to information arriving at the control room:

Information is received by the control room, (by any media).
Does this information need to be recorded, (or is it already in digital form)?
- Record if appropriate.

Who needs to know this information?
- Notify relevant stakeholders.

Assess – what is the impact of this information for:
- Safety?
- Continuing operations?
- Shift plan?

Do we need to take any immediate short term action?
What are our options?
Initiate and coordinate action.

A degree of capability is required by mine control personnel to be able to enact the template:

Skills to use systems to record information.
Assess the relevance of information for a range of stakeholders.
Communicate effectively to both engage and cooperate with stakeholders.
Interpret the impact of the information at multiple levels.
Knowledge of both the mine and procedures to initiate immediate action.
Understand the mining process sufficiently to plan, initiate and coordinate action.
Have sound decision-making capability.
Ability and authority to give instructions and directions.

Now revisit the earlier example in a context of monitoring and control:

An underground jumbo has a hydraulic failure.
The jumbo operator moves to the nearest radio coverage and calls mine control reporting the failure.
Mine control acknowledge the call and enter the stoppage into the computer system. Depending on the system and digital communications coverage, the stoppage may be displayed in relevant locations or on supervisor’s tablets.
Mine control then calls either the operations or maintenance supervisor, possibly both, to report the failure.
Mine control assess impact of this stoppage:
- Safety – no immediate concerns.
- Continuing operations – Will delay completion of drilling heading with flow on to charge up and possibly delay firing beyond proposed end of shift firing window.
- Shift plan – charging and firing delayed
Mine control liaise with a range of stakeholders: supervisors, planners, engineers, grade control, etc to plan any immediate action to be taken in this ‘out-of-control’ situation. E.g:
- Prioritise use of maintenance personnel.
- Re-assign charge up crew to another heading as next job.
- Update plan for next shift to accommodate heading not being fired.
Mine control coordinate implementation of changed plan.

In the paper ‘Mine Control – Why do we do it, and how do we Achieve Sustainable Success?’ (Ballantyne, 2010) this author discusses various staffing models for mine control room personnel. The highest ranked success factor is the calibre of control room personnel.

The question arises as to whether mine control personnel are expected to carry out: monitoring, control, or both monitoring and control.

Another anecdote

An underground gold mine in Western Australia.

In this instance the control room was staffed by a leading hand fitter/mechanic. ‘Rob’ had over 10 years working in equipment maintenance underground.

A radio call to mine control came from a jumbo operator regarding a blown hose. Rob knew the equipment well and was able to liaise with the jumbo operator and establish which hose had blown.

Rob then checked with the site warehouse and established that there were no such hoses on site.

Knowing the procurement process, Rob was able to order the hose from the supplier in Kalgoorlie and have it dispatched by courier in less time than it would have taken for the jumbo operator to reach the surface.

What Rob did constitutes ‘control’. He had the knowledge and authority to take action to address an ‘out of control’ situation.

There have been cases where the monitoring and control roles have been explicitly separated. E.g. A large Australian caving operation during development circa 2010. In this instance, there were two data capture clerks collecting data by voice radio calls and entering it to a computer system. An operations foreman, operations planner and maintenance foreman were also located in the control room on all shifts using live displays of the data for real time decision making.

In smaller mines it is common for there to only be one person in mine control covering both monitoring and a degree of control. Often in these cases the formal description of the ‘mine control’ role is largely just monitoring but, depending upon the calibre of the personnel, a degree of implicit ‘control’ develops.

This is Part 1 of a 2-part article. Read Part 2 here.