Analysis and Prediction of the Thiourea Gold Leaching Process Using Grey Relational Analysis and Artificial Neural Networks

Rui Xu,Xiaolong Nan,Yongbin Yang,Feiyu Meng,Bin Xu,Qian Li,Xuling Chen,Tao Jiang

doi:10.3390/min10090811

Abstract

The thiourea (TU) leaching of gold from refractory ores can be considered an alternative to cyanidation. However, the high reagent consumption causes an increase in cost, which seriously limits its use. In order to effectively reduce the TU consumption, it is necessary to analyze the influencing parameters of gold recovery and TU consumption and apply them to the prediction of the TU leaching process. This paper investigated six potential influencing parameters and used grey relational analysis (GRA) to analyze the relational degree between each parameter and gold recovery and TU consumption. Then, the artificial neural network (ANN) model was established to simultaneously predict the gold recovery and TU consumption in the TU gold leaching process. The results of the GRA indicated that the leaching time, initial pH, temperature, TU dosage, stirring speed, and ferric iron concentration were all well related to the gold recovery and TU consumption. Therefore, the incorporation of these parameters can significantly improve the ANN model validation. The predictive results noted that the prediction accuracy of gold recovery varied from 94.46% to 98.06%, and the TU consumption varied from 95.15% to 99.20%. Thus, the predicted values corresponded closely to the experimental results, which suggested that the ANN model can accurately reflect the relationship between the operational conditions and the gold recovery and TU consumption. This prediction method can be used as an auxiliary decision-making tool in the TU gold leaching process, and it has broad engineering application prospects in engineering.

Highlights

Cyanidation has remained a dominant technology in the gold industry for more than a century because of its simplicity and economy
The relational degree of temperature was the highest, followed by the leaching time, but stirring speed had a little influence on the TU consumption
77.6% of gold was extracted at a leaching time of 4.0 h, with an initial pH of 1.5, temperature of 35 ◦ C, TU concentration of 6.0 g/L, stirring speed of 400 r/min, and ferric iron concentration of 9.33 g/L using 8.1 kg/t of TU

Summary

Introduction

Cyanidation has remained a dominant technology in the gold industry for more than a century because of its simplicity and economy. There are some disadvantages, such as its high toxicity and slow kinetics. Gold occurs as submicroscopic particles in carbonaceous minerals; sulfides; and minerals containing arsenic, copper, and manganese, which can cause a high cyanide consumption and low gold recovery using the cyanide leaching method [1]. It is necessary to research non-cyanide leaching reagents for gold for the depletion of ores which are open to cyanidation and to improve the environmental requirements. Of the non-cyanide reagents, TU and thiosulfate have gained significant research interest over the last few decades [5,6,7]

Methods

Results

Conclusion