How To Get Gold From Gold Ore? 4 Gold Ore Extraction Methods
What is gold ore?
Gold ore is also known as gold deposit, in which the main mineral is natural gold, with pyrite, arsenopyrite, white iron ore, arsenopyrite, etc. for the most part. Gangue ore mainly includes quartz, chalcedony, sericite, organic carbon, etc., of which gold wrapped in pyrite accounts for about 73%, gold wrapped in arsenopyrite accounts for more than 15%, and gold wrapped in gangue mineral accounts for more than 11%. Today, it is closely related to arsenic, and is mainly contained in arsenopyrite, arsenopyrite, etc.
Main gold ore types
The common seen gold ore are placer gold ore and rock gold ore.
Placer gold ore
The placer gold ores are essentially formed by the long-term water erosion and downstream wind erosion of some large gold deposits. The processing of placer gold ore is mainly gravity concentration and enrichment.
Rock gold ore
Generally, rock gold ores can be divided into quartz vein type, altered rock type in fracture zone, vein disseminated type and quartz calcite type from the perspective of mineral processing.
Quartz vein type gold deposit
The quartz vein type gold ore is mainly pyrite, and the gold ore mainly exists between the gangue and pyrite or other metallic ores. Most quartz vein type gold ores belong to easy dressing gold deposits, and high recovery can be obtained by heavy flotation or single flotation.
Altered rock type gold ore in fracture zone
The gangue of the altered gold ore in the fracture zone is mainly quartz and sericite, the metal mineral is mainly pyrite, and gold is associated with sulfide ore. This type of ore deposit is usually easy to concentrate, and high recovery can be obtained through single flotation. If the weathering is serious, the tailings can be recycled for the second time through all slime cyanidation.
Vein disseminated gold ore
Vein disseminated gold ores are relatively complex, and the most obvious feature is the disseminated output of gold minerals. It is difficult to obtain a better recovery index of this mineral through a single flotation process.
Quartz calcite type gold ore
The gangue minerals of quartz calcite gold ore are quartz and calcite. Because of the good distribution of gold and the great influence of metal minerals on the mineral selection process, it is difficult to obtain good mineral selection indicators through a single process.
If gold is to be extracted (separated), it needs to be crushed and finely ground first, and then separated from other gangue minerals by various beneficiation methods (including gravity separation, flotation, etc.). The process is as follows:
Gold ore crushing and grinding process
Generally, before the gold ore enters the beneficiation process, it is necessary to crush and grind the material to fully separate the ore. First, the gold ore is sent to the crusher for crushing to a certain particle size. This process needs to go through one or two or more stages of crushing process. In the middle, the particle size is separated by the screening machine. Qualified gold ore is directly sent to the ball mill to continue grinding. Unqualified minerals are screened and returned to the crusher by the belt conveyor for further crushing.
In the grinding stage, similar to crushing, need to go through one or two or more stages. This link needs to be graded by hydro-cyclone or grader equipment. Qualified grinding gold ore directly enter the dressing stage, while non-qualified materials need to be graded back to continue grinding.
Why do we need crushing and grinding before beneficiation?
There are two main reasons:
First, coarse crushing and grinding of large gold ores;
Second, in order to ensure the stability of beneficiation indexes, high concentrate grade and tailing grade, it is necessary to separate minerals from gangue minerals.
In the beneficiation process of gold ore, the instability of indicators, the sidedness of concentrate, the high grade of tailings and the large medium mineral rate are often due to the insufficient degree of dissociation. Gold ore crushing is to prepare raw materials for grinding, and grinding is the continuation of ore crushing. Grinding of ball mill equipment is the final process to achieve full dissociation. Therefore, gold ore crushing and grinding are indispensable and important links before beneficiation.
Gold ore crushing is to prepare raw materials for grinding, and grinding is the continuation of ore crushing. Grinding of ball mill equipment is the final process to achieve full dissociation.
According to the survey, most gold concentrators in China use jaw crusher for coarse crushing, standard cone crusher for medium crushing, and short head cone crusher for fine crushing. Most medium and small gold concentrators use two-stage closed circuit ore crushing, while large gold concentrators use three-stage closed circuit ore crushing process.
Gold ore beneficiation process
In the beneficiation process, due to the different types and properties of gold ores, different beneficiation methods are adopted, but new processes of gold extraction by gravity concentration, flotation and heap leaching are generally adopted.
4 gold extraction methods
1. Flotation method
The flotation method can enrich gold to a large extent in the sulfide mineral concentrate, which is convenient for discarding tailings as soon as possible and reducing the cost of the beneficiation stage.
The flotation method is often used to treat polymetallic ores, which can realize the efficient comprehensive utilization of mineral resources and the comprehensive utilization of polymetallic ores. The disadvantage is that the recovery rate of oxidized ore is low, and it is difficult to collect coarse gold particles.
The main equipment of the flotation method is the flotation machine. In addition, it is also equipped with ball mill, dryer, spiral classifier and other equipment. The equipment plays an irreplaceable important function and role, and is responsible for gold ore concentration, grinding, drying, grading and other work.
2. Gravity concentration method
Due to the large proportion of gold, gravity separation is another common method for recovering gold, and it is also often used in combination with other mineral processing methods to treat various gold ores. The placer gold ore is basically treated by gravity concentration method.
In the gravity concentration plant of gold ore, the commonly used gravity concentration equipment is jigger, spiral chutes, etc.
3. Cyanide method
Cyanide leaching is one of the main methods to recover gold. It has the advantages of high recovery rate, fast speed, and strong adaptability to gold ore, and can produce gold locally, so it has been widely used. Cyanide leaching of gold can be divided into tank leaching (stirring leaching) and heap leaching (percolation leaching).
However, if there are reducing substances (sulfides) in the gold ore, the chlorine consumption will be too large. In addition, the acidic chlorine containing solution has strong corrosivity, so there are high requirements for the equipment.
4. Heap leaching method
The low-grade ore containing gold is stacked on the anti-seepage mat, and low concentration alkaline cyanide solution is sprayed on the ore pile to dissolve the gold. The gold containing solution is leached out from the ore pile, and then the gold is recovered by activated carbon adsorption or zinc powder replacement precipitation.
Heap leaching method has the advantages of short process, low cost, easy operation and quick effect, so it has been widely used in gold separation industry. Due to the low leaching rate of some granulated columns of coarse ore samples, the cost of leaching rate of all granulated columns of fine ore samples is high.
Gold ore resources are very precious. In order to separate vein gold ore more reasonably, it is recommended to conduct beneficiation test first, comprehensively analyze the ore properties, and obtain a scientific beneficiation test report, so as to judge which vein gold ore beneficiation technology should be used, and determine the beneficiation plan after comprehensively considering the actual situation, investment and other factors of the gold ore concentrator, so as to achieve an ideal rate of return on investment.
And for the gold ore processing equipment, customers should choose reliable manufacturers, such as Zenith. As a professional manufacturer, Zenith has over 30 years’ experience, and their beneficiation equipment has been sold to over 170 countries and regions all over the world. And the engineers will recommend machines for you according to your specific requirements.