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Gold containing pyrite cinder industrial test and transferred to industrial production, achieve better technical and economic benefits Qianxi County chemical plant in Hebei Province in 1982 by the daily processing capacity of 25t scale.
First, physical properties
The acid-making raw material of Qianxi County Chemical Plant is basically the cyanide tailings of Jinchangyu Gold Mine. The slag after desulfurization by boiling in a boiling furnace is a raw material for cyanidation leaching of gold. Most of the metal minerals in the slag are oxidized minerals. The gold in the cyanidation tailings is very fine, mostly below 0.01mm, and is extremely fine particulate gold, mostly wrapped in gold. It is also difficult to dissociate the gold monomer by a single grinding method. Only after calcination and hydration can most of them be leached by cyanidation.
Second, the gold extraction process
The industrial production process is to burn the slag after desulfurization by boiling roasting in the acid making process. After the hydrazine, grinding, dense dehydration and alkali treatment, the gold is recovered by the conventional gold cyanide- zinc wire replacement method.
(1) The process flow is shown in Figure 1.
Figure 1 Flow chart for recovery of gold from pyrite
(2) Process conditions
The calcination temperature is 840 ~ 890 ° C; grinding classification; overflow concentration is 6%; graded overflow fineness is -360 mesh accounted for 83%; discharge fineness is -360 mesh accounted for 74%; Ф6000 thickener feed concentration It is 7.5% to 8%; the fineness of the infusion raw material is -360 mesh, 80%; the concentration of Ф6000 dense dehydration is 55% to 60%; the concentration of Ф7000 washing I concentration is 55% to 60%; The concentration is 33%; the alkalinity of the leaching pulp, pH=10.5-11.
Ф2000 stirring leaching tank: impeller line speed 7.121m / s; aeration volume 0.1 ~ 0.2m 3 / (m 3 · min); NaCN concentration 0.025% ~ 0.03%; CaO concentration 0.025% ~ 0.03%; leaching time 8.5 h.
Replacement time, 79min.
The amount of sodium cyanide: 946 g / t.
The amount of lime used was 6.77 kg/t (pH = 10.5).
Lead acetate dosage: 300g/t.
Bleaching powder dosage: 5kg / t.
(III) The results of the analysis of the gold mud obtained by the test are shown in Table 1.
Table 1 Analysis results of gold mud and zinc wire head elements
Golden mud
element
Au
Ag
Cu
Pb
Zn
S
SiO 2
Al 2 O 3
CaO
MgO
Fe
content/%
0.3775
0.162
0.042
46.86
11.56
3.83
2.18
0.96
14.15
0.39
2.25
Zinc wire head
element
Au
Ag
Cu
Pb
Zn
content/%
0.456
0.0127
0.824
6.57
83.91
Note: The zinc wire has been treated.
The gold content of the cyanide gold mud obtained in the test is about 0.4%.
(4) Test indicators
Leaching rate: 77.00% Washing rate: 98.02%
Replacement rate: 99.83% Total cyanide yield: 75.35%
Smelting recovery rate: 95% total gold recovery rate: 71.58%
Every two gold costs 281.08 yuan. Calculated according to the treatment of slag 25t / d, the annual recovery of gold 703.72 two, the annual profit of 150,000 yuan.
Third, the process characteristics of slag gold extraction
The gold-containing slag cyanide gold extraction process has its own characteristics in addition to the conventional cyanide gold extraction process.
(1) The roasting acid-making raw material for the slag-removing gold in the Qianxi County Chemical Plant is precisely the cyanide-treated iron sulfide, which has a gold grade of about 4g/t, of which the gold is densely wrapped by pyrite and veins, only through The roasting causes cracks, pores, and looseness of the minerals, and the gold can be dissociated. Roasting is mainly caused by temperature. 600～700°C is the best temperature for gold extraction, but it is the temperature of SO 3 which is unfavorable for acid production. 850～900°C is the best temperature for acid production, but the process of leaching gold is unfavorable. It is the purpose of achieving by-product gold without affecting the acid production.
(2) The discharge of the slag has two types: dry discharge and water discharge. The process adopts rapid cooling of the slag, especially the red hot slag is directly discharged into the cold water, and the sudden cooling will increase the cyanide gold extraction index.
(3) From the industrial test, the indicators are relatively stable, with low investment and quick effect. Therefore, it can be promoted and applied in chemical plants with similar raw materials, which is of practical significance for making full use of national resources and accelerating the development of gold production.
In February 1985, the Rushan Chemical Plant of Shandong Province used the Changchun Gold Research Institute to treat gold-containing sulfuric acid slag by cyanidation, and the process was identified. Leaching rate of 67.97%, washing rate of 97.30%, the replacement rate of 98.87%, 97.60% metallurgical recovery of gold total recovery of 63.82%; gold annually about 100 kg; white silver 134kg; annual profit of 67 million yuan.