A bewildering array of process control instrumentation is currently available for mineral processing plants. For sequencing control, special purpose microprocessors or the process control computer can be used._x000D_
Where continuous control is required, then the choice is between pneumatic controllers, electronic controllers, shared display micro- processor systems and direct digital control._x000D_
The benefits of each system are discussed and the advantages of using direct digital control in mineral processing plants are outlined. The factors which need to be considered when selecting control systems for new plants are listed. Instrumentation systems designed by Fluor Australia are used as case studies to illustrate the selection process. For established plants, conversion to direct digital can be advantageous, and case studies are given. However, replacement of existing systems requires justification based on a productivity improvement which will allow the control equipment to be paid for within a specific time period. Productivity improve- ments maybe assessed in terms of increased