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Effects of lead nitrate and pre-aeration on the deportment of base/precious metals in cyanide leaching of a pyritic refractory gold concentrate

Deveci Hacı, Yazıcı Ersin Yener, Celep Oktay, Mercimek Murat, Demirel Cumhur, Çakmak Serkan, Cingöz Melih Baki, Kavlu Ömer Hami, Kömürcü Hüseyin

Physicochemical Problems of Mineral Processing

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2023

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Vol. 59, iss. 5

art. no. 166259

EN

This study was undertaken to improve gold and silver extraction from a pyritic gold flotation concentrate, which assayed 11 g/t Au, 42 g/t Ag, 0.21% Cu, 3.57% Zn, and 31% Fe. Direct cyanide leaching of the concentrate at 1.5 g/L NaCN yielded a low gold extraction (37%), confirming its refractory nature. Effects of lead nitrate (200-500 g/t Pb(NO3)2) and pre-aeration (24 h) before cyanide leaching at 1.5-3.5 g/L NaCN were investigated. Earlier studies have focused on the impact of these parameters on gold leaching. Besides gold, this study demonstrated the behaviour of silver and base metals (copper and zinc) from the pyritic gold concentrate. Adding lead nitrate had a negligible effect on gold extraction whilst improving silver extraction. Dissolution of copper was substantially suppressed by adding lead nitrate, i.e., from 23% (no Pb(NO3)2) to 4% (500 g/t Pb(NO3)2) over 24 h. Zinc dissolution was negligible (≤0.01%). Pre-aeration of the concentrate improved the gold and silver extractions by 4-14% and 23-44% at the subsequent cyanide leaching (1.5-3.5 g/L NaCN). However, it did not affect the leaching of copper. Only negligible leaching of zinc (≤0.6%) occurred during cyanide leaching. Pre-aeration also reduced cyanide consumption in subsequent cyanide leaching (1.5 g/L NaCN), i.e., from 2.83 kg/t to 2.03 kg/t NaCN per solids. These results suggested that lead nitrate can improve silver extraction while suppressing copper dissolution, which would be advantageous in the leaching-adsorption circuit (CIP), mitigating the dissolved copper-associated problems. Pre-aeration can also be suitable for improved gold/silver extractions and reduced reagent consumption.

2

Comparing cyclohexyl hydroxamic acid and benzohydroxamic acid in cassiterite flotation under lead nitrate activation

Yang Hao, Ou Leming

Physicochemical Problems of Mineral Processing

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2023

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Vol. 59, iss. 6

art. no. 174673

EN

This paper investigates the flotation behavior of Cyclohexyl hydroxamic acid (CHA) and benzhydroxamic acid (BHA) on cassiterite under lead nitrate activation conditions and elucidates the adsorption mechanism of CHA on the cassiterite surface. Microflotation experiments were performed to compare the capturing efficiency of CHA and BHA at pH values ranging from 4 to 12. Results showed that CHA exhibited superior capability in capturing cassiterite compared to BHA. The recovery of cassiterite in the hydroxamic acid-based flotation system correlated positively with the adsorption of hydroxamic acid on the cassiterite surface. Adsorption experiments revealed an increase in adsorption quantity with an increase in hydroxamic acid dosage, with CHA exhibiting significantly higher adsorption amount than BHA on the cassiterite surface. To analyze the adsorption mechanism of CHA on the cassiterite surface, both infrared spectroscopy and X-ray photoelectron spectroscopy (XPS) analysis were conducted, both before and after lead nitrate activation. IR spectra and XPS results indicated that lead ion activation enhanced the adsorption of CHA on the cassiterite surface, resulting in an increased number of active sites for CHA interaction. Additionally, chemisorption of CHA occurred on the cassiterite surface.

3

The influence of pre-aeration on cyanide leaching of a non-refractory sulphide gold and silver ore

Aydin B., Basturkcu H., Gul A.

Physicochemical Problems of Mineral Processing

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2015

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Vol. 51, iss. 2

647--660

EN

The leaching behaviour of a sulphide gold-silver ore was investigated in terms of a relationship between gold and silver extractions and cyanide consumption. Ninity five Au % and 88.0% Ag extractions were obtained under the determined conditions of 24 h leaching duration, -74 μm particle size, 40% solids ratio, 4 g/dm3 NaCN concentration, and 450 rpm stirring speed with NaCN consumption of 3.35 g/dm3. Since the NaCN consumption was higher than in industrial applications, Pb(NO3)2 and H2O2 additions and aeration using an air pump were tested during leaching in order to decrease the consumption. While Pb(NO3)2 addition with aeration caused a decrease in the metal extractions, the individual or combined additions of H2O2 and aeration could not provide a reduction in the cyanide consumption. Therefore, the effect of the pre-aeration followed by cyanidation was tested. Eventually, applying 4 h of pre-aeration before a shorter leaching duration of 12 h provided 92.0% Au and 90.5% Ag extractions with a reduced NaCN consumption of 2.44 g/dm3.

4

Influence of lead nitrate on cyanide leaching of gold and silver from turkish gold ores

Sayiner B.

Physicochemical Problems of Mineral Processing

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2014

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Vol. 50, iss. 2

507--514

EN

Effect of lead nitrate addition on cyanidation of Havran, Ovacık, Mastra LCu (low copper) and Mastra HCu (high copper) gold ores was investigated by laboratory tests at the Ovacik Gold Mine Metallurgy Laboratory. Leach tests were performed at optimum NaCN additions and pH values while different lead nitrate additions were applied. Ovacik cyanidation plant leaching time, 24 hours for the constant 100 Mg/h ore feed rate was applied as optimal for all lead nitrate tests. Results showed the increase in gold and silver recoveries between 0.4-1.2% for gold and 3.9-11.6% for silver at the end of 24 hours leaching by the addition of lead nitrate as 0.1-0.5 kg/Mg. NaCN consumption decreased or did not change except for the Ovacik ore. In the case of the Ovacik ore it slightly increased.

5

Effect of lead(II) ions on the intensity and extent of infection of Galleria mellonella L. caterpillars by the entomopathogenic nematode Heterorhabditis megidis (Poinar, Jackson and Klein 1987)

Matuska J., Kamionek M.

Chemia i Inżynieria Ekologiczna

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2006

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Vol. 13, nr 6

553-557

EN

The degree of environmental contamination by heavy metals is closely associated with life functions of entomopathogenic nematodes which are presently used as one of biological means of plant pest control. The paper presents results of a study on the effect of lead(II) ions on the development of Heterorhabditis megidis population. Water solutions of lead nitrate in concentrations of 40, 100, 500, 1000 and 5000 ppm Pb2+ were used. Test insects were infected by surviving larvae. The mortality of invasive nematode larvae after 5 days long contact with lead ions, the mortality of test insects that contacted lead treated nematodes and the extensity and intensity of invasion were determined. Biological activity of Heterorhabditis megidis was observed to decrease with the increased concentration of lead ions.

PL

Stopień skażenia środowiska metalami ciężkimi ma ścisły związek z funkcjami życiowymi nicieni entomopatogenicznych, które obecnie są wykorzystywane jako jeden z biologicznych środków ochrony roślin przed szkodnikami. W pracy przedstawiono wyniki badań nad wpływem jonów ołowiu(II) na rozwój populacji Heterorhabditis megidis. Zastosowano wodne roztwory azotanu ołowiu w stężeniach: 40, 100, 500, 1000 i 5000 ppm Pb2+. Larwami, które przeżyły, porażano owady testowe. W doświadczeniu oznaczono śmiertelność larw inwazyjnych nicieni po 5 dniach kontaktu z jonami ołowiu, śmiertelność owadów testowych poddanych kontaktowi z nicieniami traktowanymi jonami ołowiu, ekstensywność i intensywność inwazji. Zaobserwowano, że wraz ze wzrostem stężenia jonów ołowiu, obniża się biologiczna aktywność Heterorhabditis megidis.