Due to the increasing scarcity of resources of gold, low-grade gold more and more attention at home and abroad, in order to properly take advantage of this part of the gold resources, a lot of research units proposed the use of "heap leaching" precious metal recovery process low-grade gold deposit in the following for low grade of oxidized gold-containing arsenic "heap leaching" production selected column leaching test process.
First, the nature of minerals
(1) Mineral composition
The test sample is taken from a point Guangdong gold, on the sample generally higher degree of oxidation, the ore loose texture, the main bulk metallic minerals, ores are: Brown iron pyrite, arsenopyrite and the like, non- Metal minerals are mainly: quartz , clay minerals, etc. The main mineral composition of ore is shown in Table 1.
Table 1 Main mineral composition %
Mineral name | Limonite | Pyrite | Arsenopyrite | quartz | Clay minerals | Bauxite | total |
content | 5 | 1 | 0.5 | 42 | 46 | 3 | 97.5 |
The multi-element analysis of ore is shown in Table 2.
Table 2 Multi-element analysis of ore%
element | Au g/t | Ag g/t | C | S | As | TFe | FeO |
content | 3.38 | 27.8 | 0.17 | 0.16 | 0.434 | 4.76 | 0.76 |
element | Fe 2 O 3 | Cu | Pb | Sb | SiO 2 | CuO | AlO 3 |
content | 5.96 | 0.016 | 0.042 | 0.13 | 62.30 | 0.23 | 18.06 |
(2) The state of occurrence of gold
Most of the gold in the ore exists in the form of invisible gold. After the water sample is sieved by water, it is repeatedly washed and washed. In the <0.075mm concentrate, it is repeatedly searched by microscope, and gold has not been found yet. Purification, limonite, pyrite, two main metal minerals for single mineral analysis, gold in the metal minerals accounted for about 30%.
Second, indoor column immersion research test
Due to the low gold grade of the ore, it is only 3.38g/t, and it is a weathered mine with a high degree of oxidation. According to this feature, the ore is more suitable for “stacking†to recover the gold. This test was carried out to provide a design basis for "heap leaching" production.
Test mainly in the ore particle size, # 1 reagent concentration, concentration of NaCN ore were studied.
(1) Granularity of ore
In this test, we used three grades on the ore particle size: 25mm grade, 20mm grade and 15mm grade, and divided the ore into 4 parts, 25mm grade 1 set as A 1 , 20mm grade 2 set as B 1 and B 2 , 15mm grade 1 is set to C 1 , and the column used for the column immersion test is 4 plastic tubes with a diameter of 100mm and a height of 4000mm.
Four ores of A 1 , B 1 , B 2 , and C 1 were respectively placed in four columns, and the column packing weights are shown in Table 3.
Table 3 ore packing weight kg
Serial number | A 1 | B 1 | B 2 | C 1 |
weight | 43.0 | 430. | 42.0 | 41.5 |
(2) Pretreatment conditions
The Effect of the pretreatment agent for various conventional cyanidation of gold effect, we believe that the effect of pretreatment reagent # 1 ore best. Therefore, in the pretreatment, we use 1 # reagent as a pretreatment agent. In terms of concentration, we used 1% 1 # reagent and 2% 1 # reagent to test, and pretreated A 1 , B 1 , C 1 with 2% 1 # reagent, B 2 1% of the 1 # reagent was pretreated, and the spray intensity of the 1 # reagent was 0.8L/(h·m 2 ).
(three) NaCN concentration
The NaCN concentration was 1.0 g/L; the spray strength was 0.8 L/(h·m 2 ). The test conditions used for each column are shown in Table 4.
Table 4 Test conditions of each column
Serial number | Test conditions |
A 1 | Particle size 25mm # 1 2% of the Pretreatment 1.0g/L NaCN Cyanide spray strength 0.8L / (h · m 2 ) |
B 1 | Particle size 20mm # 1 2% of the Pretreatment 1.0g/L NaCN Cyanide spray strength 0.8L / (h · m 2 ) |
B 2 | Particle size 20mm 1% of the pretreatment reagent # 1 1.0g/L NaCN Cyanide spray strength 0.8L / (h · m 2 ) |
C 1 | Particle size 15mm # 1 2% of the Pretreatment 1.0g/L NaCN Cyanide spray strength 0.8L / (h · m 2 ) |
(four) spraying operation process
Column Leaching spraying in two stages: Reagent # 1 spray, spray of NaCN, # 1 spray reagent 15h day continuous spray interval 9h oxidation, continuously 15d.
The NaCN spray is sprayed continuously for 12 hours every day for 12 days at intervals of 12 hours. Pretreatment reagent # 1, A 1 column, B 1 column, spray column C 1 to 15d, pH value of 11.5 to 12, and B 2 is sprayed onto the column 20d, pH value of 11.5 to 12, this phenomenon It is because the A 1 column, the B 1 column, and the C 1 column are pretreated with 2% 1 # reagent, while the B 2 column is pretreated with 1% 1 # reagent, and the high concentration 1 # reagent has better effect on the ore treatment. Column # 1 B 2 reagent consumption 5.12g / t, A 1 column, B 1 column # 1 average consumption of reagents 6.12kg / t C 1 column.
During the NaCN cyanide spray process, the columns were sprayed to 14d, and the gold content of the spray liquid was reduced to less than 1mg, and the individual reached 0.00mg/L. NaCN was also not consumed, reaching the equilibrium point. The spraying process was taken every two days. Once again, the cyanidation results are shown in Table 5.
Table 5 Column leaching cyanide results
Serial number 0 | Cyanide out Au Metal amount mg | Au in the tailings Metal amount mg | Cyanide rate% |
A 1 B 1 B 2 C 1 | 141.98 143.12 117.88 159.92 | 16.34 16.77 22.68 15.36 | 89.68 89.51 83.86 91.24 |
The results show that pretreatment reagent # 1 - flow of the mine and then cyanide was more appropriate.
Due to the pretreatment of 1 # reagent, the cyanidation effect of the gold oxide ore was greatly improved, the cyanidation rate was greatly improved, and the cyanidation time was only 14 days.
The above results were analyzed: B 2 was pretreated with 1% of 1 # reagent, and its cyanidation rate was also slightly lower (83.86%), while A 1 , B 1 and C 1 were pretreated with 2% of 1 # reagent, cyanide. The relative rates are also relatively high: 89.68%, 89.51%, and 91.24%.
From the aspect of particle size analysis: A 1 is 25mm, B 1 is 20mm, C 1 is 15mm, C 1 cyanidation rate is up to 91.24%, but only a little more than a percent higher than A 1 , B 1 , so The particle size has little effect on the cyanidation rate.
The consumption of NaCN to 14d is basically not consumed, and the NaCN consumption is shown in Table 6.
Table 6 NaCN consumption of each column
Serial number | Mine weight kg | Add the amount of NaCN g | The amount of remaining NaCN g | NaCN consumption kg/t |
A 1 B 1 B 2 C 1 | 43 43 42 41.5 | 16.8 16.8 16.8 16.8 | 7.49 7.85 8.75 7.50 | 0.174 0.182 0.208 0.181 |
It can be seen from the table that B 2 has a poor pretreatment effect with 1% of 1 # reagent, and the NaCN consumption is correspondingly increased to 0.208 kg/t, and the cyanidation rate is also slightly lower.
(5) Activated carbon adsorption
Stirring adsorption was used for 24 h. The adsorption results of activated carbon are shown in Table 7.
Table 7 Activated carbon adsorption results
Stock volume ml | Raw liquid Au content mg ​​/ L | Raw liquid Au total mg | Remaining volume ml | Residual liquid Au content mg/L |
500 | 12.08 | 6.04 | 518 | 0.28 |
Activated carbon adsorption rate:
Third, the conclusion
(1) The fine-grained gold deposit is difficult to cyanide, but the results of this test prove that the high-oxidation fine-grained gold deposit can be used in this process to obtain a high 83% to 91.24%. index.
(2) This sample is pretreated with 1 # reagent - cyanide process is appropriate, and in 1 # reagent, NaCN consumption can be reduced to a lower level, the ore contains a certain amount of arsenide is not conducive to cyanidation, but It has little effect on cyanide leaching.
Therefore, the production of heap leaching of low-grade oxide gold mine that arsenic, we recommend pre-treatment reagent # 1 - cyanide process, help make full use of gold resources, its economic and social benefits will be considerable.
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