Ўзбекистон республикаси фанлар академияси навоий бўлими ташкил этилганининг 5 йиллигига бағишланган “фан, таълим ва ишлаб чиқаришнинг

 

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МЕЖДУНАРОДНАЯ НАУЧНО-ПРАКТИЧЕСКАЯ КОНФЕРЕНЦИЯ 
«ИНТЕГРАЦИЯ НАУКИ, ОБРАЗОВАНИЯ И ПРОИЗВОДСТВА – ЗАЛОГ ПРОГРЕССА И 
ПРОЦВЕТАНИЯ», ТОМ I, ГОРОД НАВОИ, РЕСПУБЛИКА УЗБЕКИСТАН, 2022 
- 103 -
Key words: refractory gold ores, pyrite, arsenopyrite, dissolution, oxidation, 
ferric iron, oxygen, catalysts, redox potential. 
Ключевые слова: упорные золотосодержащие руды, пирит, 
арсенопирит, растворение, окисление, трехвалентное железо, кислород, 
катализаторы, окислительно-восстановительный потенциал.
Gold bearing ores are becoming more complex and low grade, facilitating to 
the development of innovations in mineral processing. Gold can be extracted 
from minerals through physical, thermal, biological, or chemical pretreatment 
processes [1]. Currently most value of gold metal processed from sulphide ores 
and pyrite (FeS
2
) is a ubiquitous form of sulphide minerals on the Earth’s surface. 
Precious metals such as gold, silver and other valuable metals’ association within 
this mineral is by far the most important reason for processing pyrite. Pyrite 
oxidation is essential economically. Frequently this mineral is the main mineral 
in an ore body and in order to release enclosed metals pyrite must be oxidized. 
Initially, in the pre-treatment of refractory gold ores, the oxidation of mineral 
must be carried out before it is subjected to the next gold leaching process 
(cyanide leaching).
The processing methods of pyrite and reaction mechanisms have been 
studied through several investigations. In terms of environment and resource 
saving a bacterial oxidation (bioleaching) process suits most. The bioleaching of 
this mineral has been postulated via an indirect mechanism involving the 
bacteria. Ferric iron leaches the pyrite, which is reduced to ferrous iron. Bacteria 
within process by maintaining a high redox potential, plays a role as oxidizer the 
ferrous iron to ferric iron.
Chemical ferric leach 
+
−
+
+
+
+
=
+
+
H
SO
Fe
Fe
O
H
FeS
16
2
15
14
8
2
4
2
3
2
2
Bacterial oxidation of ferrous iron regenerating ferric iron 
O
H
Fe
H
O
Fe
2
3
2
2
2
4
4
4
+
→
+
+
+
+
+
The existence of an indirect mechanism implies that the bacterial and 
chemical subprocesses can be characterized separately. The bacterial oxidation of 
ferrous iron has been found to be a function of the ferric/ferrous ratio [2]. Only 
through ferric leaching this ratio also could be obtained at the beginning of the 
process, but the redox potentials were much lower than those encountered in 
bioleaching. Setting redox potential within solution could lead to effective 
oxidation process [3]. Investigations alternative source to maintain enough redox 
potential would be the subject of this thesis. 

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