Coal Preparation

Commissioned Study on Process Control and Instrumentation in Coal Preparation

Coal Preparation » Process Control

Published: July 93Project Number: C3043

Get ReportAuthor: Chris J Clarkson, M Gunn, D Wiseman, Chric Wood | JK Tech

The JKTech study group surveyed personnel from coal preparation plants, equipment suppliers, consultants and coal industry policy makers. The survey found that the industry requirement for process control techniques was varied. and related to the level of sophistication, style of operation and resource/market relationships. A number of areas emerged in which further process control development can be both directly and indirectly used to achieve increased profitability for a large number of operations.  Reacting to market pressure, the industry is implementing TOM to reduce product variability. Improved process control may allow this to be achieved without undue yield loss or increases in handling costs.

The priority issues emerging from the survey are:

  • Plant feed control - blending, analysis for feed forward control of separation processes, minimisation of feed biases between parallel lines.
  • Dense medium process control - cut point control in parallel circuits, particularly at low density, requires further work
  • Flotation circuit stabilisation and control of product ash.
  • Thickener control.
  • Ash determination on line - reliable and accurate sensors, calibration practice, sampling and analysis procedures.
  • Product stockpile control and blending control.

Where basic PID control loops have been installed and maintained, the industry reports a qualitative benefit. This primarily derives from achieving stable inputs to separation processes and stable internal components of the process. Many operations appear to perform well at this level, with process cut points selected on the basis of resource and market information and requirements. Those operators with digital supervisory systems regarded them well, particularly when the resources were available for system maintenance.

The study revealed that on line washability monitoring was perceived by some in industry as a potential solution to supervisory process control (le. manipulation of the process cut points). The industry also regarded the various ash gauge devices as poor performers.

The separation process with most potential for yield gain through improved process control is froth flotation.

The problems of scarce, inaccurate and noisy measurements, variable feeds and unbalanced process lines, require further study of alternative control techniques. Those developed and used by the petrochemicals industries are not necessarily the best techniques for the coal preparation environment.

The technology and skills exist to achieve basic stable process control, and success is a function of dollars spent on effective design, maintenance and training. A range of problem areas, such as technical staff turnover, management support, operator skills and supplier support affect each operation differently in its endeavours to achieve improved operating efficiency.

The operators with relatively mature systems perceive significant potential for development of advanced control systems. There is a general acknowledgment of a severe lack of information regarding:

  • resource characteristics and mining schedule control in real time,
  • process efficiency in real time and the actual process cutpoints. Better  information will be necessary for higher level control development.

The problem of limited information and the potential for advanced control must be addressed in conjunction with the control philosophy debate. The philosophy determines which information is required for control purposes.

While the validity of the 'equal incremental ash' approach is generally accepted, there is ongoing debate in the industry about how best to implement this philosophy, and about the most appropriate place to undertake blending.

The study has also identified process continuity and availability as a critical issue. Development of the information acquisition/management capability of modern process control systems can assist in minimising process on-off events, which translates into increased yield and product quality. Maintenance based on equipment condition monitoring via data management from the process control system will benefit both plant availability and process continuity.

In summary, the study recommends support for:

  • Consolidation of instrumentation and stabilising control approaches by demonstration in selected plants or alternatively by documentation of current best practice.
  • Development of effective feed splitting and distribution systems.
  • Development of a management system for information which embraces
  • coordination of resource data, plant performance characteristics and product quality and tonnage targets.
  • Equipment condition monitoring and planned maintenance
  • ash monitor performance and calibration.
  • A study of the potential for advanced control techniques to allow use of the quality of data realistically obtainable from the current generation of instruments.
  • An investigation into the performance of on-line ash measurement devices and their associated support systems.
  • A study of the relative costs of plant engineering approaches versus process control implementation to enable definition of an optimum approach to plant performance improvement (eg. feed blending versus schedule and process control).
  • Preparation and maintenance of a technology transfer resource to give operators access to successful case studies and methodologies of process control implementation.

The study has identified several strategies by which the industry can effectively assimilate, apply and sustain process control techniques appropriate to the needs and constraints of coal preparation.

The strategies can be summarised as follows:

  • Demonstration
  • Education and technology transfer
  • Integration of process knowledge, engineering practice, operating practice and the market imperative with well tried process control equipment and techniques.


Health and safety, productivity and environment initiatives.


Open Cut

Safety, productivity and the right to operate are priorities for open cut mine research.

Recently Completed Projects

C19024Establishing Ecologically Sustainable Mine Water Release Criteria In Seasonally Flowing Streams

Extreme rainfall conditions in the Fitzroy Catchment over an approxi...

C25030Coal Mine Open Pit Final Void Closure And Relinquishment - Addressing Uncertainty In Coal Mine Environmental Planning

This report addresses uncertainties faced by coal mine operators whe...

C27046Estimation Of True Deformation Vector From Slope Radar Monitoring

Slope deformation radar monitors are now widely used in open cut coa...

Open Cut

Coal Preparation

Maximising throughput and yield while minimising costs and emissions.

Recently Completed Projects

C27004Improving Coal Flotation With Oscillatory Air Supply

This report provides detailed information on coal flotation with os...

C25018Improving Solids Recovery And Moisture Reduction In Ultrafine Coal Dewatering

This report provides detailed information on fine coal dewatering in...

C27028Lab Froth Flotation Testing Guide With Coal Quality

Correct outcomes from laboratory froth flotation testing in coal bor...

Coal Preparation

Technical Market Support

Market acceptance and emphasising the advantages of Australian coals.

Recently Completed Projects

C26039Nanoporosity In Cokes: Their Origin, Control And Influence On CO2 Reactivity

This project using the outcomes of previous project C24060, examine...

C28063A Comprehensive Technical Review Of High-Efficiency Low-Emission (HELE) Pulverised Coal Combustion Technologies For Power Generation

Research and development has been undertaken worldwide to realise co...

C28064Carbon Structure Transformation During Coking Of Australian Coking Coals: Better Understanding The Coke Formation

Carbon structures of coke that are formed during the plastic layer a...

Technical Market Support

Mine Site Greenhouse Gas Mitigation

Mitigating greenhouse gas emissions from the production of coal.

Recently Completed Projects

C28076Selective Absorption Of Methane By Ionic Liquids (SAMIL) - Phase 2 Demonstration In A Packed Bed Reactor

An alternative approach to high temperature oxidation of ventilation...

C26004CFD Modelling Of Reverse Thermal Oxidisers For VAM Abatement - CFD Modelling Of Fixed-Bed RTO Devices

The project is part of a larger multi‐phase program of study a...

C27058Technological Assessment Of A Recycle Reactor For VAM Abatement

Underground coal mining emits high volumes of methane, diluted in ve...

Mine Site Greenhouse Gas Mitigation

Low Emission Coal Use

Step-change technologies aimed at reducing greenhouse gas emissions.

Recently Completed Projects

C17060BGasification Of Australian Coals

Four Australian coals were trialled in the Siemens 5 MWth pilot scale ga...

C17060AOxyfuel Technology For Carbon Capture And Storage Critical Clean Coal Technology - Interim Support

The status of oxy-fuel technology for first-generation plant is indicate...

C18007Review Of Underground Coal Gasification

This report consists of a broad review of underground coal gasification,...

Low Emission Coal Use

Mining And The Community

The relationship between mines and the local community.

Recently Completed Projects

C16027Assessing Housing And Labour Market Impacts Of Mining Developments In Bowen Basin Communities

The focus of this ACARP-funded project has been to identify a number...

C22029Understanding And Managing Cumulative Impacts Of Coal Mining And Other Land Uses In Regions With Diversified Economies

The coal industry operates in the context of competing land-uses that sh...

C23016Approval And Planning Assessment Of Black Coal Mines In NSW And Qld: A Review Of Economic Assessment Techniques

This reports on issues surrounding economic assessment and analysis ...

Mining And The Community


National Energy Research,Development & Demonstration Council (NERDDC) reports - pre 1992.

Recently Completed Projects

1609-C1609Self Heating of Spoil Piles from Open Cut Coal Mines

Self Heating of Spoil Piles from Open Cut Coal Mines

1301-C1301Stress Control Methods for Optimised Development...

Stress Control Methods for Optimised Development and Extraction Operations

0033-C1356Commissioned Report: Australian Thermal Coals...

Commissioned Report: Australian Thermal Coals - An Industry Handbook