The use of known model information in the design of an active disturbance rejection controller reduces the magnitude of the “total disturbance” and consequently improves the control performance.

Based on Takagi–Sugeno (T-S) fuzzy modeling, Choe Hak Jin, a researcher at the Faculty of Metallic Engineering, proposed a new method for incorporating the known nonlinear dynamics of the plant into a linear active disturbance rejection controller (LADRC),

In order to evaluate the effectiveness of the proposed method, he performed simulations of a cart inverted pendulum.

The simulation results show that the estimation burden of the extended state observer is reduced and the control performance is improved in the proposed method than in the conventional model-assisted LADRC that can incorporate only linear model information, and that the proposed cascade control scheme has good disturbance rejection, transient response and robustness at the same time.

If further information is needed, please refer to his paper “A cascade control scheme with T-S fuzzy model-assisted linear active disturbance rejection controller for position tracking of cart inverted pendulum” in “International Journal of Dynamics and Control” (SCI).

The viscosity of slag is a very important factor in understanding the rate of metal-slag chemical reactions and the mass transfer taking place in the pyrometallurgy process. It is also vital for ensuring stable operation of metallurgical furnaces. Therefore, accurate prediction of the viscosity of slag is of great importance not only for the operation stability and productivity in the pyrometallurgy process but also for high yield.

Up to now, many researchers have carried out various viscometric experiments of slag, and many models have been developed to estimate its viscosity. However, the previously developed slag viscosity prediction models are mostly for solid-free slag.

Since most metallurgical slag necessarily contains MgO, it is very important to develop a model for predicting the viscosity of CaO–SiO₂–Al₂O₃–MgO system slag.

Ro Tae Song, a researcher at the Faculty of Metallic Engineering, has proposed a viscosity prediction model of CaO–SiO₂–Al₂O₃–MgO system slag using the multi-gene genetic programming (MGGP).

The proposed viscosity model is a simple algebraic equation with varying basicity, Al₂O₃ content, MgO content and temperature of slag. Furthermore, the average relative error between experimental data and the calculated values using the model is 25.10%, which is comparatively small.

For more information, please refer to his paper “Viscosity Prediction of CaO–SiO₂–Al₂O₃–MgO System Slag Using MGGP” in “Transactions of the indian institute of metals” (SCI).

Now cyanidation is the main method for producing gold from gold ore/concentrate.

It is well-known that gold in ore/concentrate is dissolved in the form of gold-cyanide complex by the action of cyanide and oxygen. During cyanidation, copper in the ore/concentrate readily reacts with cyanide to form stable cyanide complexes and under ordinary cyanidation conditions Cu(CN)₃^2- is the dominant species in leach solution. Thus, the recovery of copper as well as cyanide from gold-plant wastewater will offer economic benefit.

AVR (acidification-volatilization-regeneration) technology, SART (sulfidization-acidification-recycling-thickening) process, electrowinning, membrane technologies, etc. have been developed to recover cyanide and/or copper, but each of these technologies has advantages and limitations and there is no universal method. Among these, AVR process has been used in industry owing to its simple principle and high effectiveness and robustness.

Kim Yong Il, a researcher at the Faculty of Metallic Engineering, evaluated sulfuric acid baking-leaching process to recover copper from precipitate containing Cu of 44.53 wt %, Fe of 5.56 wt % and S of 16.81 wt %, which comes from cyanidation wastewater treatment process by AVR (acidification-volatilization-regeneration) technology in a gold plant.

The experimental results showed that by acid baking under following conditions of 250℃, 60 min and the ratio of H₂SO₄ to copper precipitate 2.4:1, ~98.5 wt % copper was released to the leach solution, and that the leachate containing Cu and Fe can be sent to the conventional SX-EW process to produce electrolytic copper.

You can find the details in his paper “Acid Baking-Leaching Process for Treatment of Copper Precipitate from AVR Process” in “Russian Journal of Non-Ferrous Metals” (SCI).