Impact of Sub Optimal Operation

The objective of this project was the 'Quantification the effects of sub-optimal operation' in a coal preparation plant. This was achieved by the analysis of particular operational issues and how they can affect the recovery of saleable coal.

Previous work in this area was piecemeal and focussed on particular issues. This has resulted in there being considerable variation in the approaches which makes comparative consideration difficult. It was decided that the conceptual framework and the outcomes from 'The Intelligent Plant' project would be employed to assist in conducting this project.

The starting position was the development of a language to describe the situation:

· Process element - unit operation in the plant;

· Measurement and symptoms - values, output from models;

· Health issues - unwanted operational situation;

· Root faults and actions - underlying problem and possible solution.

In this context, the health issues are also sub-optimal operation conditions.

While the entry mechanism into 'The Intelligent Plant' diagnostic system was via the symptoms/measurements, this project required the inversion of the system to allow entry via a health issue. The selection of a health issue, that is a sub-optimal event, allows symptoms to be identified. This required some commentary on discussing the difference. The level of the impact required the use of a model (termed 'Linkage Map') in this report. From this, comments on the potential root faults and actions can be made. It needs to be noted that the system was reviewed and updated.

The outcomes are:

· A template methodology to allow this type of analysis to be conducted on a particular coal preparation plant and mine site; and

· A number of case studies illustrating the use of the methodology and the outcomes from its application.

A total of 19 case studies were considered in this project. These were selected with consultation with the ACARP Coal Preparation Sub-Committee.

The analysis methodology used in all of the case studies can be summarised as:

· Development of a Linkage Map between the relevant variables via an appropriate model;

· Clear definition of the Sub-Optimal Operation (Health Issue);

· Identification of associated Symptoms and Measurements; and then

· Identification of the Root Faults and what Actions that potentially can be applied.

In all the cases, it was found that this methodology was capable of providing a summary of the situations on a consistent basis.

That is, the objective of the project has been achieved, hence it is recommended that a second stage project is supported.

The objective would be to modify the existing 'Intelligent Plant Diagnostic' System to allow access not only from a Symptom/Measurement entity, but also via a Health Issue (Sub-Optimal Operation) entity. Since the current System is now eight years old, it is also considered that the EXCEL worksheet is updated.

The outcome of the current project will allow an experienced metallurgist/process engineer to describe a sub-optimal operation in a consistent manner and permit estimates of the costs of the situation given a particular feed washability to the plant. The approach to overcome the situation can also be identified and a cost/benefit analysis constructed.

It needs to be recognised that some of Root Faults are due to undisciplined mining practices.