1.gold ore and gold

Gold Mine

Gold mines refer to gold ore, where gold ore is obtained through mining operations, and gold ore refers to mineral aggregates with a certain gold content that can be used by industry. Gold, from which it is selected, is a rare, precious and stable metal that has always been a symbol of wealth and status.

gold-mine

Gold mining is the process of extracting ore (metal-rich rock) from the earth's crust. Like other minerals, the formation of these deposits involves a lot of geological action. Modern gold mining is mostly carried out in areas with a high concentration of gold-bearing ores (ore bodies). Today, 60 to 70 percent of the world's gold production comes from surface mines, while the rest comes from underground mines.

However, as a precious metal, gold has become an important part of the foreign exchange reserves of various countries in the world, and it is also one of the important strategic materials.

gold

The main use of gold

Gold is rare, special and precious, and has been regarded as the first of the five elements since ancient times. Among metals, it has the title of "King of Metals" and enjoys an unparalleled reputation for other metals. Due to the excellent characteristics of gold, gold has played the functions of currency in history, such as value scale, means of circulation, means of storage, means of payment and world currency. Since the development of capitalism, gold has become synonymous with financial reserves and currency. With the development of society, the monetary function of gold is declining, and its application in industry and high-tech fields is gradually expanding.

There are three main types of gold used today:

① It is used as an international reserve. At present, gold still occupies a very important position in the financial reserves of many countries, including major Western countries;

② Used as jewelry decoration, gorgeous gold jewelry has always been a symbol of a person's social status and wealth;

③ Application in industry and science and technology, electronic technology, communication technology, aerospace technology, chemical technology, medical technology are all inseparable from gold.

 

2.How does gold ore extract gold?

The gold mining process is usually determined by the physical, chemical and mineralogical properties of the gold ore and gangue. For example, gold ore with a large difference in specific gravity and a coarse dissemination particle size is generally treated by gravity separation; the wettability of the mineral surface is different. Large, disseminated and fine-grained gold ore is generally treated by flotation.

For some complex refractory gold ores, in order to maximize the recovery rate of gold and recover other useful components, it is undoubtedly technically necessary and economically reasonable to choose a multi-process combined process.

gold mining process

Two common gold ore beneficiation methods

① Quartz vein type gold ore

The beneficiation process of quartz vein type gold ore is mainly cyanidation method and flotation method. The determination of the process mainly depends on the particle size of gold and the symbiotic relationship with other minerals. When the surface of the ore is contaminated or there is free gold in a thin film, jig gravity separation can be used to recover a part of the gold to reduce the grade of tailings and reduce the cyanidation leaching time.

When the flotation of the ore is good, the flotation of gold ore containing quartz can produce tailings that are similar to those treated by cyanidation. In most cases, the cyanidation method is commonly used in quartz vein-type gold ore, and the main considerations are the ore grinding fineness, the cyanide concentration in the pulp, and the leaching time. At the same time, in order to reduce the amount of cyanation work, the process of re-cyanation of flotation concentrate can be used.

Quartz vein type gold ore

② Sulfide gold-bearing ores

Most of the gold-bearing sulfide ores can be treated by flotation method, and some can also be treated by cyanidation method, or combined method, or amalgamation, gravity separation or combined process.

The choice of flotation or cyanidation process depends on the recovery rate of gold and the comprehensive utilization of associated minerals. It is more difficult to dissolve and difficult to recover by flotation. When the surface of the gold particles is clean and there are no harmful components to amalgamation in the ore, the amalgamation method is more effective than the gravity separation method. In production practice, the commonly used beneficiation process of gold-bearing sulfide ore is: flotation first, and the flotation concentrate can be directly cyanated, or regrind and then cyanided, or treated by gravity separation and amalgamation.

Sulfide gold-bearing ores

Gold ore beneficiation process

The gold ore beneficiation process is mainly divided into several stages: crushing and screening - grinding and classification - sorting - tailings treatment.

① Crushing and screening stage

Gold ore grinding and classification equipment

Usually gold ore has low content, fine particle size and complex composition. The commonly used crushing and screening process in the industry is mainly a three-stage closed-circuit process, that is, through coarse crushing, medium crushing, fine crushing and screening to crush minerals to a suitable particle size . The common three-stage-one closed-circuit process is as follows:

equipmentClassificationProduct granularity(mm)
Jaw crusher (coarse crushing, fine crushing)Simple swing jaw crusher, complex swing jaw crusher160~320
Gyratory crusher (coarse crushing)Center discharge gyratory crusher, hydraulic gyratory crusher75~320
Cone crusher (medium and fine crushing)Spring cone crusher, hydraulic cone crusher22~75
screening machineCircular vibrating screen, linear vibrating screen0~12

② The grinding stage

Rock gold ore grinding operation usually adopts one stage or two stages of grid ball mill + overflow ball mill, and the second stage grinding operation and spiral classifier or hydrocyclone form a closed loop to ensure the fineness of grinding. In view of the shortcomings of traditional mills such as rapid wear and high energy consumption, we have carried out a series of transformations on ball mills, such as adopting new wear-resistant rubber linings, changing rolling bearings to sliding bearings, and increasing the size of the mill. , while improving the operation rate of the mill, it also prolongs the service life of the equipment, creating economic benefits for the enterprise. 

grinding stage

③ Mineral processing stage

rock-gold-and-placer-gold

Gold beneficiation stage is divided into two types, one is placer gold beneficiation and the other is rock gold beneficiation. The gold concentrate content of placer gold ore is high, and most of them exist in the form of sand particles. Therefore, during the separation, the gravity separation process is often used. After the pretreatment, desliming and washing, the gravity separation method can directly obtain coarse gold ore particles ;

placer gold beneficiation

Rock gold ore mainly selects the appropriate gold selection process according to the ore composition and composition. The commonly used gold selection processes are mainly cyanide gold selection process, flotation gold selection process, and gravity gold selection process. 

rock gold beneficiation

④ Tailings treatment stage

At present, the commonly used tailings treatment methods mainly include tailings reselection, tailings dewatering (tailings dry discharge) and tailings filling goaf.

1. Gold tailings re-selection process

Although the content of useful components in gold tailings is relatively low, the use of advanced technology and reasonable process for tailings re-selection can also recover the useful components in tailings to a large extent, so that resources can be fully recycled and used to reduce final The output of tailings can alleviate the pressure of tailings on the environment.

2. Gold tailings dry discharge process

In the gold ore beneficiation stage, the pulp often contains a large amount of water. Too high water content in the tailings can easily lead to tailings dam failure. Therefore, in the beneficiation plant, the concentration and dehydration of tailings is also one of the important links, and dry tailings are often used system.

Tailings

3. Gold tailings fill goaf

Gold tailings fill goaf is to use tailings waste, after treatment, to refill the goaf area, which can protect the landform and reduce the cost of tailings dam. At present, the main methods of tailings filling goaf are full tailings cement filling technology and high water consolidation full tailings filling technology.

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