MODELING THE NEW LKAB KIRUNA CONCENTRATOR WITH USIM PAC(C)

LKAB has started the construction of a new concentrator at Kiruna, wit h a capacity of 5 Mtpy. The flowsheet of the new grinding circuit is t echnically innovative and critical because it entirely relies on ore b reakage properties. It includes primary fully autogenous closed circui t grinding and secondary pebble milling. A critical size class of the magnetite ore is extracted from the autogenous mill and used as pebble s. In 1992, LKAB decided to adapt and use a simulator of the new conce ntrator. USIM PAC(C) was selected as the support software package, and a modelling team was set up, including both specialists of process mo delling and simulation and specialists of the process itself. Specific model development included development of a phenomenological populati on balance pebble mill model, and adaptation of an existing Control In ternational autogenous mill model. Model parameters were derived from extensive large scale pilot plant tests, and specific laboratory tests were performed to determine pebble mill breakage and selection functi ons for various types of pebbles and of ores. The simulator was used b y the project team for comparing alternative flowsheets (one or two li nes, various refinements), for predicting the influence of changes in throughput and plant feed grade, and for evaluating several options fo r equipment sizes. Additionally, the simulator helped understanding th e process in depth and the way the unit operations interact in this pa rticular case.