10×104t heap heap leaching practice in Saerbulak Gold Mine

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Xinjiang SAERBULAKE gold mine 10 × 10 4 t heap leach test is 1988--1992 National science and technology research projects focus on gold from the mine low-grade gold heap leach technology research and advisory center to take charge. It was completed in the indoor column immersion test and 2.4×100t on-site heap leaching test. It was completed in April-December 1990. The ore was immersed in the original ore grade of 3.62 years old. The ore was 110174t, and the gold leaching rate reached 90.61%. The total recovery rate was 90.61%. 87.75%, the production of gold reached 350kg, the output value was 21.84 million yuan, the profit and tax was 1,17,577,000 yuan, which realized the construction of the project in the same year. The experiment was completed in the same year, the results were produced, the gold was produced, the loan was repaid in the same year, the profit was obtained, and the advanced technology and economy were adopted. Significantly with social benefits. In 1991, the mine produced ore 12×10 4 t and produced 375 kg of gold. In 1992, it completed 16×10 4 t of annual heap leaching ore and produced 406 kg of gold.
The Saerbulak gold mine in Fuyun County, Xinjiang is located 38km west of the county seat and about 650km away from Urumqi. The mining area is a hilly terrain, located in a remote desert, and has a continental climate. Perennial drought and windy, annual rainfall of 150mm, annual evaporation of 1734mm, the highest temperature of 39 ° C, the lowest temperature of -49 ° C, frost-free period of 140d, five to six months a year for the freezing period.
The mine has proven surface oxidized ore reserves of 80×10 4 t, grade 2.5~4g/t, and mine thickness of 6~10m. The ore body is shallowly buried and suitable for open pit mining. The main minerals in the ore are quartz , feldspar , kaolinite, weathered feldspar, calcite , mica and volcanic glass, accounting for about 96% of the total. Secondary minerals are brown iron pyrite, arsenopyrite and arsenopyrite like weathering, about 2.8% of the total. In the oxidized ore, the gold carrier mineral pyrite is oxidized to limonite, and the poisonous sand is weathered into scorodite, leaving only a small amount of pyrite and arsenopyrite. The upper ore is mainly oxidized ore, with gold inlaid grain size, crack development, ore weathering and crushing, low degree of muddy, less harmful impurities affecting cyanidation, favorable for cyanide solution penetration and leaching, suitable for cyanide heap leaching Gold. The results of chemical analysis of ore are shown in the table.

Raw ore chemical analysis results

project

Au*

Ag*

S

Cu

Pb

Zn

As

Al 2 O 3

Content /%

3.42

0.075

0.021

0.08

0.004

0.043

1.22

15.53

project

Fe 2 O 3

TiO 2

K 2 O

Na 2 O

SiO 2

CaO

MgO

P 2 O 5

Content /%

6.57

0.82

1.55

5.25

58.59

3.57

1.08

0.107

project

MnO

CO 2

H 2 O

Sb*

Se*

Pt*

Pd*

　

Content /%

0.12

2.04

2.47

19.2

0.31

0.07

0.003

Note: * Its content is × 10 -6 .

Through 12 indoor column leaching tests on 8 different particle sizes, it was found that all kinds of ore with different particle sizes have better leaching results. The average grade is 2.55-3.43g/t, the leaching rate is 83.6%-90.3%, which is close to the whole mud cyanidation index (91.1%), which is very suitable for gold extraction by heap leaching. The on-site heap leaching particle size is -40mm, which can be granulated. The ore affects the content of harmful impurities in cyanide leaching, the consumption of sodium cyanide is not high, and the color of gold is high (95.12%-96.66%). In the crushing operation, lime is added as a protective base to raise the pH to shorten the heap leaching cycle. [next]
The principle of gold withdrawal in the entire mine includes open pit mining, crushing, pile-up... until electrolytic smelting, refining the balance (see Figure 1)

Mechanized piles are fully used according to local equipment conditions. The open-pit mining ore is crushed by a 250mm×400mm tiger mouth and transported to the yard with a 500mm wide multi-segment belt conveyor. The mobile belt conveyor with adjustable height is used, and the crawler bulldozer is used to parallel the 1m layer. The law piles up and the amount of ore piled up in the day reaches 1000-2000t. The built piles have a good structure, and the permeability of each part of the pile is uniform. There is no “artificial pool”, and the spray can be guaranteed for more than 7-8h every day. See Figure 2 for the process of crushing and building.

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The liquid distribution method is the key to increasing the leaching rate in the heap leaching operation. If the cloth liquid is not uniform, it will cause dry spots and dead spots in the ore heap. The gold in the ore will not be leached, which will reduce the leaching rate. The method of the mine cloth is mainly drip, which is the first time in China, and only the spray cloth is used in one pile area. The two types of pipelines, nozzles and drip-emitting tubes are all made of plastic parts, and control devices are installed to flexibly adjust the pressure, direction and strength of the leachate according to temperature and wind direction. Two different methods of cloth liquid have achieved the desired effect, which lays a good foundation for the final high leaching rate, in which the leaching effect drip is better than the spray.
In the production practice, the sodium cyanide concentration is controlled to be low during the spraying process. At the beginning of the leaching, the mass fraction is 0.1% sodium cyanide, the leaching is reduced to 0.05%, and the leaching is maintained at 0.02%. The average concentration of time is controlled at around 0.03%. According to the specific conditions of the mine in different leaching stages, the dynamic control spray intensity range is 8-15L/(m 2 ·h). The spraying time is in accordance with the spraying for 1h, stopping for 2h, the wind is stopped, and the principle of wind stopping and spraying is mastered. The final average consumption of sodium cyanide dropped to 181g/t, reaching the international advanced level, reducing costs and improving environmental conditions. At the same time, it also inhibits the dissolution of impurities in the ore, and reduces the content of impurities in the rich liquid. The qualified gold color is more than 982 。.

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