Guangxi Senhe High Technology Co.,Ltd.
Dedicated to Eco-friendly Gold Extraction
Heap leaching
1、Project name：Mexico Yekola gold mine
Project background: Yekola gold mine is a large open-pit deposit with heap leaching process. 9600 tons of solid sodium cyanide is needed yearly for this mine. It is difficult to get approval for purchasing sodium cyanide,as it is a highly toxic chemical and regulated strictly by government.Transportation,management and use of sodium cyanide is very inconvenient, which greatly increases the enterprise operating costs.And the environmental protection policy around the world is more and more severe. All these factors make the enterprise very difficult to use sodium cyanide.
2、Heap leaching flow chart by GDA
3、Heap leaching production data Comparison between GDA and cyanide
| ITEMS |
Cyanide in heap leaching test | GDA in heap leaching test | ||||
| Ore volume（Mt） | 1000.00 | 1000.00 | 1000.00 | 1000.00 | 1000.00 | 1000.00 |
| Gold average grade（×10-6） | 0.75 | 1.00 | 1.30 | 0.75 | 1.00 | 1.30 |
| Particle size | ＜5cm | ＜5cm | ＜5cm | ＜5cm | ＜5cm | ＜5cm |
| Total gold（g） | 750.00 | 1000.00 | 1300.00 | 750.00 | 1000.00 | 1300.00 |
| Lime consumption（Kg） | 8500.00 | 8500.00 | 8500.00 | 8000.00 | 8000.00 | 8000.00 |
| Pregnant solution PH | 10~11 | 10~11 | 10~11 | 11~12 | 11~12 | 11~12 |
| Reagent consumption（Kg） | 65.00 |
75.00 |
83.00 |
55.00 |
65.00 |
72.00 |
| Heap leaching period（day） | 25 |
25 |
25 |
22 |
22 |
22 |
| Gold grade in tailings（×10-6） | 0.110 |
0.105 |
0.114 |
0.097 |
0.090 |
0.096 |
| Leaching rate（×10-2） | 86.7 |
89.5 |
91.2 |
87.1 |
91.0 |
92.6 |
| Gold recovery volume（g） | 611.10 |
850.79 | 1115.79 | 627.38 | 873.87 | 1166.03 |
| Recovery rate（×10-2） | 81.48 |
85.08 |
85.83 |
83.65 |
87.39 |
89.01 |
4、Heap leaching production data Comparison between GDA and cyanide
| Heap leaching | GDA | Cyanide | Result comparision |
| Dosage（Kg） | 55~72 |
65~83 |
GDA consumes less |
| Period（Day） | 22 |
25 |
GDA reacts faster |
| Gold average grade in tailings（×10-6） |
0.097~0.095 |
0.100~0.114 |
GDA obtains higher leaching rate |
| Leaching rate（×10-2） | 87.1~92.7 |
86.7~91.2 |
|
| Recovery rate（×10-2） | 83.65~89.01 |
81.48~85.83 |
GDA obtains higher recovery rate |
| Reagent nature | Ordinary chemical | Highly toxic chemical | GDA has no limitation on transportation/storage/use |
5、Index Comparison of waste water
| Heap leaching | PH | Suspended solids (SS) |
Chemical Oxygen Demand |
As | Hg | HCN |
| GDA(mg/L) | 8.28 | 147 | 13.81 | 1.676µg/L | 0.001 | 0.034 |
| NaCN(mg/L) | 8.24 | 219 | 21.64 | 1.702µg/L | 0.002 | 3.671 |
| PMSF | Sulphide | Cu | Pb | Cn | Cd | Fe |
| 0.2650 | 0.005L | 0.05L | 0.2 L | 0.05 L | 0.05 L | 0.03 L |
| 0.2650 | 0.005L | 0.05L | 0.2 L | 0.05 L | 0.05 L | 0.03 L |
* While test results lower than detection limit, write down the LOD and add“L“
6、Index Comparison of waste residue
| Heap leaching | Total mercury |
HCN | As | Cr6 | +Total chrome | Cu |
| GDA(mg/L) | 0.05 | 0.15 | 0.3 | 0.86 | 2.08 | 0.06 |
| NaCN(mg/L) | 0.08 | 3.25 | 0.3 | 1.23 | 5.11 | 0.08 |
| Cn | Cd | Pb |
| 0.10 | 0.02 | 0.057 |
| 0.45 | 0.065 | 0.065 |
GDA shows obvious advantage on environmental protection when compare the index of waste water and residue with cyanide. While using GDA, the waste water can be discharged without special treatment and it has well satisfied discharge standard.