The Pyhäsalmi Concentrator – 13 Years of Computer Control

Abstract

When the Pyhasalmi concentrator started its production in 1962 the operation was quite conventional: rod and ball milling, quite a number of small flotation machines, the goal of process control was to produce concentrates of constant quality and instrumentation was rather elementary.Later metal grinding was replaced by total autogenous grindin big new type OK-flotation machines were installed, instrumentation was modernized, the X-ray pulp analyzers and the process computer were acquired. During the years process control has been developed towards economic control which means that the goal is no longer to produce concentrates of constant quality but to maximize the net cash flow of the whole mine.The paper describes the main stages of this development work. The control systems of grinding and flotation are also described. The three stage autogenous grinding is controlled to the maximum feedrate by controlling power draw, filling rate and pulp density of the mills. The control systems of both Cu-flotation and Zn-flotation comprise fast stabilizing control and slow adaptive optimizing control. The control is based on the economic recoveris and the process models.The one-line economic supervising system, the benefits of computer control and the structure of the new computer system to be installed at the end of 1983, are briefly described.