1. Vertically, from the head of the placer gold ore (upstream) to the tail of the placer gold body (downstream), there is generally no change in the first taste of the ore body and the low grade of the tail. However, due to the influence of landforms and mineral sources, one to several enrichment areas are often seen in placer gold ore bodies.
2. In the horizontal direction, the grade of placer gold varies greatly, and there is no certain rule
3. In the vertical direction, the bottom grade of placer gold ore body is high and the top grade is low, sometimes the difference is several times to tens of times, or even hundreds of times.
4. Under the premise of only one mineral source, the placer gold ore body has high taste in the first part, low grade in the tail part, low grade in the place where the placer gold ore body spreads, and high grade in the shrunk place.
5. At the confluence of non-ore ore flow and ore-bearing tributaries, the placer gold grade becomes lower.
6. The greater the mixed sand thickness of placer gold mine, generally speaking, the lower the grade of mixed placer gold of placer gold mine.
two. So how to mine the placer gold mine with low grade?
The methods of beneficiation of placer gold mine are as follows: screening, crushing, re-selection, purification, smelting, etc.
Placer Gold Mine Processing Method
1. Screening: This method of beneficiation is mainly the use of vibrating screen or drum screen, the principle is similar, the vibrating screen has the advantages of strong processing capacity, long service life, etc. The drum screen has the advantages of thorough screening and good screening effect. Different types of equipment are selected for grades of ore. Vibration screens are generally used for sifting the ore sands that require large processing capacity.
2.Crushing: Blasting methods of placer gold mines basically never use crushing methods and equipment. The so-called crushing mainly refers to the crushing of mud clumps due to the large amount of mud, so that the gold wrapped in the mud can be dissolved It can improve the recovery rate of the gold separation process, and there is no need to carry out the crushing process for sand mines with small or no mud content. The crushing of placer gold ore is usually completed by adding water to the screening equipment. For the placer gold ore with more mud and stickiness, the ore washing machine can be used to remove the excess mud.
3. Gravity Separation: rough gold separation of placer gold mines is generally carried out by re-election method, the equipment used includes chute, jig, etc. The beneficiation of placer gold ore with very low content generally needs to go through the coarse chute separation, throw away most of the waste sand, and then the chute concentrate then enters the jig to be sorted to obtain the coarse concentrate with higher gold content. The significance of rough selection of chute and selection of jig is to improve the efficiency of beneficiation, ensure recovery rate and beneficiation efficiency. The purification of placer gold ore can be carried out by gravity separation or amalgamation. At present, the application of the amalgamation method is more common. The forced amalgamation cylinder is used to amalgamate and purify the gold concentrate produced by the jig, which can be discarded , The extraction of gold, the recovery rate is higher than 95%.