Study on Harmless Disposal and Mechanism of Cyanide Tailings of a Gold Mine by Oxidation Roasting

doi:10.12068/j.issn.1005-3026.2024.02.014

Abstract

Abstract:

In view of the high complex cyanide ratio in cyanide tailings of a gold mine， the process of oxidation roasting was adopted to treat cyanide tailings. The results showed that the total cyanogen content in cyanidation tailings could be reduced below the detection limit 0.04 mg/kg when the samples were roasted at 550 °C for 30 min， at 20% O₂ volume fraction and a total gas of 600 mL/min， at the same time， the sulfur retention rate reached 82.22%. Thermogravimetric analysis of the corresponding ferricyanide complex K₄Fe（CN）₆ showed that K₄Fe（CN）₆ is first oxidized to KCNO， and then oxidized to K₂CO₃. Both stages are accompanied by gaseous compounds such as CO₂， CO， NO₂ and NO， and the first stage also involves sub-reactions. The process can not only effectively decompose cyanide， especially complex cyanide in the cyanide tailings， but also avoid the easy oxidation of sulfur element in the tailings， greatly reducing the cost of subsequent flue gas desulfurization， and has broad application prospects.

Key words: cyanide tailings, roasting, complex cyanide, oxidative decomposition, harmless disposal

CLC Number:

TF 532

Yan SONG, Bing ZHAO, Yan-jun LI, Ling-bo ZHAO. Study on Harmless Disposal and Mechanism of Cyanide Tailings of a Gold Mine by Oxidation Roasting[J]. Journal of Northeastern University(Natural Science), 2024, 45(2): 262-269.

Figures/Tables 15

Table 1 Mass fraction of main elements in cyanide tailings sample of a gold mine in Inner Mongolia

SiO₂	Al₂O₃	CaO	Fe	MgO	K	Na	含水	烧失量	C	S	Pb	As
55.42	13.08	6.65	5.17	3.60	2.16	1.795	3.88	4.67	1.30	1.18	0.001	<0.01

Fig. 1 XRD analysis results of cyanide tailings sample

Table 2 Sulfur phase analysis of cyanide tailings sample

硫物相	硫化物中硫	硫酸盐中硫	自然硫	总硫
质量分数/%	0.98	0.19	0.01	1.18
分布率/%	83.05	16.10	0.85	100.00

Fig. 2 Schematic diagram of the roasting system of the horizontal tubular roaster

Fig. 3 Effect of O2 volume fraction on oxidative decomposition of cyanide

Fig. 4 Effect of O2 volume fraction on sulfur retention rate

Fig. 5 Effect of gas flow on oxidative decomposition of cyanide

Fig. 6 Effect of gas flow on sulfur retention rate

Fig. 7 Effects of calcination temperature on oxidative decomposition of cyanide and sulfur retention rate

Fig. 8 Effects of calcination time on cyanide release under different calcination temperatures

Fig. 9 Effects of calcination time on sulfur retention rate under different calcination temperatures

Fig. 10 XRD analysis results of oxidized samples

Table 3 Chemical phase analysis of sulfur element in samples

硫物相	硫化物	硫酸盐	自然硫	总硫
质量分数/%	0.13	0.83	0.01	0.97
分布率/%	13.48	85.39	1.13	100

Fig. 11 TG?DTG?DSC thermogravimetric analysis results of ferric ferrocyanide

Fig. 12 Results of MS mass spectrometry analysis of ferric ferricyanide

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