Wyniki wyszukiwania - BazTech

1

Simultaneous optimization of flotation column performance using genetic evolutionary algorithm

Nakhaei F., Irannajad M., Yousefikhoshbakht M.

Physicochemical Problems of Mineral Processing

|

2016

|

Vol. 52, iss. 2

874--893

EN

Column flotation is a multivariable process. Its optimization guarantees the metallurgical yield of the process, expressed by the grade and recovery of the concentrate. The present work aimed at applying genetic algorithms (GAs) to optimize a pilot column flotation process which is characterized by being difficult to be optimized via conventional methods. A non-linear mathematical model was used to describe the dynamic behavior of the multivariable process. The solution of the optimization problem using conventional algorithms does not always lead to convergence because of the high dimensionality and non-linearity of the model. In order to deal with this process, the use of a genetic evolutionary algorithm is justified. In this way, GA was coupled with the multivariate non-linear regression (MNLR) of the column flotation metallurgical performance as a fitting function in order to optimize the column flotation process. Then, this kind of intelligent approach was verified by using mineral processing approaches such as Halbich’s upgrading curve. The aim of the optimization through GAs was searching for the process inputs that maximize the productivity of copper in the Sarcheshmeh pilot plant. In this case, the simulation optimization problem was defined as finding the best values for the froth height, chemical reagent dosage, wash water, air flow rate, air holdup, and Cu grade in rougher and column feed streams. The results indicated that GA was a robust and powerful search method to find the best values of the flotation column model parameters that lead to more reliable simulation predictions at a reasonable time. Based on the grade–recovery Halbich upgrading curve, the MNLR model coupled with GA can be used for determination of the flotation optimum conditions.

2

Application of D-optimal design for optimizing copper-molybdenum sulphides flotation

Nakhaei F., Irannajad M., Sam A., Jamalzadeh A.

Physicochemical Problems of Mineral Processing

|

2016

|

Vol. 52, iss. 1

252--267

EN

Froth flotation is widely used for concentration of base metal sulphide minerals in complex ores. One of the major challenges faced by flotation of these ores is selection of the type of flotation reagents. In this study, the D-optimal experimental design method was applied to determine the optimum conditions for flotation of copper and molybdenum in the rougher flotation circuit of the Sungun copper concentrator plant. The investigated parameters included types and dosages of collectors and frothers, diesel dosage and feed size distribution. The main effects on copper and molybdenum recoveries and grades were evaluated. Results of optimization showed that the highest possible grade and recovery were obtained for Z11 as a primary collector (20 g/Mg), R407 as a first promoter collector (20 g/Mg), X231 as a second promoter collector (7 g/Mg), A65 (15 g/Mg) and Pine oil as frothers (5 g/Mg), 20 g/Mg of diesel dosage, and d80 of feed size was equal to 80 μm. The analysis of variance showed that the primary promoter collector was the most significant parameter affecting the recovery of Cu, while diesel dosage and d80 were the most significant parameters influencing the Mo recovery.

3

Investigation of effective parameters for molybdenite recovery from porphyry copper ores in industrial flotation circuit

Nakhaei F., Irannajad M.

Physicochemical Problems of Mineral Processing

|

2014

|

Vol. 50, iss. 2

477--491

EN

The Sarcheshmeh copper mine is a significant copper and molybdenum producer. Sampling of the Sarcheshmeh flotation circuit (in a six-month period) showed that a large share of waste of molybdenite took place in rougher cells. Since the rougher cells tailing is transferred to tailing thickener, the main focus of this paper was on this section. In the current study, the factors which influence the recovery of molybdenite and copper were investigated. Molybdenite recovery in the bulk flotation circuit was consistently lower than that of the copper sulphides as well as being far more variable. This paper describes the methodically use of size by size recovery data, quantitative mineralogy, and liberation degree analysis to identify the factors contributing to molybdenite recovery relative to copper in industrial rougher circuit. The results showed that the size by size recovery for both metals in the ultrafine and coarse fractions recovery was reduced. On the other hand, the highest recovery occurred in the intermediate sizes from 27 μm to 55 μm. Molybdenum recovery in the fine and ultrafine and coarse fractions drops off to a greater extent than the recovery of copper. The investigations of degree liberation showed that the recovery of copper sulphides is more dependent on the liberation state of valuable minerals while for molybdenite some other factor splay a significant role.

4

Prediction of on-line froth depth measurement errors in industrial flotation columns: a promising tool for automatic control

Nakhaei F., Irannajad M.

Physicochemical Problems of Mineral Processing

|

2013

|

Vol. 49, iss. 2

757--768

EN

The pulp-froth interface position is important from a metallurgical point of view because it determines the relative importance of the cleaning and the collection zones. The pulp-froth interface position is measured based on variations of specific gravity, temperature or conductivity between the two zones to locate the pulp froth interface position. In this study, the pressure measurements are used to calculate the values of the froth layer height. These two meters are installed in the upper part of the column at 1.4 m and 2.4 m respectively, from the top of the column. Methods using pressure gauges are commonly used in industrial operations Even though their accuracy is limited (due to assumptions of uniformity of the pulp and froth density), and they always have some error. In the Sarcheshmeh copper industrial plant (Iran), a float was installed near the column with 2.5 m height that was calibrated to 5 cm intervals in order to determine the more exact forth height and compare it with the recorded froth height in control room. In this paper, an algorithm based on Kalman Filter is presented to predict on-line froth height errors using two pressure gauges. This research is based on the industrial real data collection for evaluating the performance of the presented algorithm. The quality of the obtained results was very satisfied. The RMS errors of prediction froth height errors was less than 0.025 m.

5

Comparison between neural networks and multiple regression methods in metallurgical performance modeling of flotation column

Nakhaei F., Irannajad M.

Physicochemical Problems of Mineral Processing

|

2013

|

Vol. 49, iss. 1

255--266

EN

Artificial neural networks are relatively new computational tools which their inherent ability to learn and recognize highly non-linear and complex relationships makes them ideally suited in solving a wide range of complex real-world problems. In this research, different techniques (Linear regression, Non-linear regression, Back propagation neural network, Radial Basis Function for the estimation of Cu grade and recovery values in flotation column concentrate are studied. Modeling is performed based on 90 datasets at different operating conditions at Sarcheshmeh pilot plant, a copper concentrator in Iran, which include chemical reagents dosage, froth height, air and wash water flow rates, gas holdup and Cu grade in the rougher feed and flotation column feed, column tail and final concentrate streams. The results of models were also expressed and analyzed by intuitive graphics. The results indicated that a four-layer BP network gave the most accurate metallurgical performance prediction and all of the neural network models outperformed non-linear regression in the estimation process for the same set of data.