The amalgamation method can be divided into two processes: internal mixed mercury and external mixed mercury. The internal amalgamation is a method of amalgamation in which the ore is ground and amalgamated in the grinding equipment . Commonly used internal amalgamation equipments include rolling mills, skimming machines, amalgamation cylinders, and special small ball mills and rod mills. Externally mixed mercury is a mercury-mixing method for amalgamation outside the grinding equipment. The commonly used external amalgamation equipment is mainly a mercury-mixing board and a mercury-mixing machine with different structures.
When gold ore containing copper, lead, zinc minimal mineral content, ore powder containing no mercury sulfide, gold and disseminated in a coarse grain size upon primary mercury amalgamation method selected from gold, commonly used intermixing Mercury method gold selection. The external amalgamation method is only used as an auxiliary means to recover some of the fine-grained gold and mercury paste overflowing from the internal amalgamation equipment such as the radon. Gold deposits often use the internal stick mercury method to separate gold particles from other heavy minerals. The internal amalgamation method is also used to treat re-selected coarse concentrates and other gold-containing intermediates, and the internal amalgamation equipment grinds and mixes mercury to recover gold particles.
When gold has a fine grain size and flotation method or cyanidation method as the main gold selection method, gold is generally selected by external amalgamation method, and is installed in the ball mill grinding cycle, classifier overflow or concentrator overflow. Amalgam plate to recover monomeric natural gold particles.
1. Internal amalgamation method The internal amalgamation equipment used in mine production is a radon mining machine, a mercury mixing cylinder and a rolling mill. The United States and South Africa use tantalum mining machines, while the former Soviet Union used a mercury mixing cylinder and a roller mill. Most mines in our country also use a mercury mixing cylinder and a roller mill.
1) The antimony mining machine is a kind of crushing machine with simple structure and convenient operation, but its working efficiency is low, the processing volume is small, the granularity of crushed ore is uneven and the grain size is coarse, and the fine grain gold cannot be fully solved. Therefore, the recovery rate of gold is low when mercury is mixed. The mercury blending of the skimmer is only suitable for the treatment of simple ore containing coarse gold and for small vein gold mines.
The boring machine is mainly composed of components such as gutters, frames, hammers and transmissions, as shown in Figure 1. When amalgam is mixed, ore, mercury and water are added into the gutter, and the drive mechanism drives the cam to make the hammer head reciprocate up and down to complete the crushing and amalgamation operation. At the time of ore discharge, a screen is installed on one side of the gutter, and the slurry is discharged from the sieve. The mercury paste in the slurry is collected by the mercury-mixing plate, excess mercury and gold amalgam that is not amalgamated. The mercury-mixed tailings are discharged from the ordinary chute after mercury removal. The chute sinking sand is selected with a gold-containing sulfide concentrate. The mercury paste and gangue in the gutter are regularly taken out and sorted by a mercury-mixing plate and a shaker to obtain a mercury paste and a gold-bearing heavy sand concentrate. [next]
The radon mining machine used in a gold mine in China is divided into two types according to the weight of the hammer head: 225kg and 450kg. The operating conditions are listed in Table 1. The lime dosage during operation is 0.5-1.0kg/t, and the liquid-solid ratio in the gutter is 6:1. After the first mercury is added, mercury is added once every 15 minutes, and the amount of added mercury is 5 times that of the original ore.
Table 1 Working conditions of a gold mine ore mining machine | |||||
project | 1 | 2 | project | 1 | 2 |
Hammer weight / kg | 225 | 450 | Feeding size / mm | <50 | <50 |
Mine size / mm | <0.4 | <0.4 | Processing capacity /[k g· ( å°Â· h)-1] | 295 | 610 |
The amount of mercury given for the first time / (g· t-1 ) | 10 | 20 | 　 | 　 | 　 |
2) Ammonia-mixed mercury-mixed mercury amalgamation tank is a widely used internal amalgamation equipment for gold processing plants. It is used to treat gold-bearing heavy sands of gold deposits and re-election gold concentrates of vein gold mines. The recovery rate of gold can reach 98% or more.
Mercury cartridges are used to recover gold from concentrates, heavy sands and various mineral processing products. The amalgamation cylinder is divided into light and heavy.
The amalgamation cylinder is a rubber-lined steel cylinder, and its structure is shown in Fig. 2. The specifications vary depending on the amount of processing, and the technical specifications are listed in Table 2.
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Table 2 Â Technical specifications of the amalgamation cartridge | ||||||||||
Mercury tube type | Internal dimensions | Loading capacity / kg | Number of revolutions / (r· min-1 ) | Power / kw | Tube weight / kg | Loading capacity / kg | Ball diameter / mm | |||
Diameter / mm | Length / mm | Volume / m 2 | ||||||||
Light weight | 700 | 800 | 0.3 | 100~150 | 20~22 | 0.5~0.75 | 420 | 10~20 | 38~50 | |
Heavy | 0-31 | 600 | 800 | 0.23 | 100~150 | 22~38 | 0.3~2.1 | 1500 | 150~300 | 38~50 |
0-3b | 750 | 900 | 0.4 | 200~300 | 21~36 | 1.7~3.75 | 2000 | 300~600 | 38~50 | |
800 | 1000 | 0.6 | 300~450 | 20~33 | 3~6 | 2600 | 500~1000 | 38~50 | ||
Although most of the gold in the re-elected gold concentrate is in a free state, the surface of the gold particles is often contaminated to varying degrees, and some gold and other minerals or gangues are in a living form. When the gold concentrate is treated by a mercury-mixing cylinder, steel balls are often added to the cylinder, and the surface film of the gold particles is removed by grinding operation and the gold particles are dissociated from the continuous body. When dealing with heavy sand concentrates containing clean free gold particles, light amalgamation cylinders are generally used, and the ball loading is small. When dealing with heavy sand concentrates with high content of continuous organisms and serious surface contamination of gold particles, heavy-duty amalgamation cylinders are often used, and 1kg of heavy sand concentrates need to be loaded with 1-2 kg steel balls. The loading amount of the mercury-mixing cylinder is related to the loading amount and the particle size and gold content of the material. The relationship is shown in Table 3.
Table 3 Â The relationship between the amount of amalgamation cartridge and the amount of ball loaded ( kg/m 3 ) | |||
Gold concentrate characteristics | Gold content / (g · t -1 ) | Material quantity / ( k g· m -3 ) | Ǿ50mm steel ball volume |
Mercury trap or jig concentrate | <500 | 500 | 800 |
>500 | 400 | 1000 | |
The suede chute has a particle size of 0.5mm concentrate | <500 | 500 | 100 |
>500 | 400 | 500 | |
The grain size of the suede chute is 0.15mm concentrate | <500 | 700 | 200 |
>500 | 600 | 300 | |
When heavy sand concentrate is mixed with mercury in a non-alkaline medium, a magnetic mercury paste is sometimes formed due to the incorporation of iron . Therefore, the internal amalgamation operation is generally carried out in an alkaline medium, the amount of lime is 2% to 4% of the charge amount, and the amount of water is generally 30% to 40% of the charge amount, and the usual grinding concentration can also be used.
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