A new integrated online process control model, Metso Outotec Process Advisor, has been started up in Rio Tinto Kennecott Flash Smelting Furnace in Salt Lake City, USA. The Flash Smelting Furnace is one of the two flash furnaces, the other being the Flash Converting Furnace.
Metso Outotec Process Advisor helps Rio Tinto’s Kennecott mine stabilize their process and optimize their results
The model is linked to both laboratory assays and DCS and the operator checks the new assays and accepts or rejects them.
Process advisor features
The Outotec Process Advisor is an expert level process control system, which can be integrated with any automation system and laboratory system through multiple ways of integration, such as OPC, Historian or direct SQL connections.
The Process Advisor model contains of an integrated feedforward and feedback model. The feedforward model calculates the amount of coolant and silica to be mixed with the concentrate assay at the wet feed mixture bins. The feedback model takes into account slag and matte assays as well as temperature to adjust the error terms (biases) of the model.
The software contains tables for feed mixture, matte/blister/metal and slag assays and melt temperatures. These are normally directly linked to the laboratory LIMS system and automation system, but they can also be manually entered in the Process Advisor.
The Process Advisor also contains filtering out of incorrect or unrealistic values. A traffic light visualization system is used for assay values and for prompting the operator when a new assay or temperature has been received. Automatic acceptance can also be used if the traffic light color for the received assay or temperature is green.
The feed mixture assays are taken every 1,5 h from each of the outlet of the feed mixture bins. There are 2 bins for concentrate mixture, 1 bin for coolant and 1 bin for silica. Since there is no blending plant, the feedforward assays are very important to be able to handle blend changes, which can be quite drastic. The feedforward estimate for the matte grade is shown on the Calculation page to indicate to the operator if there is a need to make an additional corrective calculation during an active blend change. Otherwise the corrective calculation is performed every time there is a feedback from the process, such as a new assay or temperature.
Example of Process Advisor Operation Screens
The commissioning took place in the beginning of 2020 in co-operation with metallurgists and operators. The model was first used on day and evening shifts and slowly was introduced in full-live operation.
Outotec would sincerely like to thank Rio Tinto Kennecott Smelter and all the operating personnel involved for the opportunity and the co-operation in this very inspiring project together with the client.
Offline blend planner models working in parallel with the Process Advisor online models have been provided. These models can be used to estimate influence of different blends on the process before taking them into use. By utilizing the error terms (biases) from the online model in place, the calculation result is very accurate, compared to traditionally used theoretical heat and material balance models.
Slag flux target has been optimized to include a more accurate fluxing target than just targeting a constant SiO2% or Fe:SiO2 ratio. The fluxing target equation can include multiple slag components known to affect the slag liquidus temperature, such as slag MgO% and Al2O3%.
This article is part of our Smelting Newsletter Issue 1/2020. Visit the issue front page for all articles and greetings from Jyrki Makkonen, Vice President of Smelting business line.