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Sulphides containing 1% to 5% are the main features of this type of ore in the composition of matter. This ore is most common in quartz veins containing gold ore. According to the state of gold production in the ore, the ore can be divided into two types, which are closely related to the symbiotic relationship between gold and sulfide, and the symbiotic relationship between gold and quartz and other gangue minerals. Although these two ores belong to the same type of quartz veins containing a small amount of sulfides, the difference in the floatability difference is also significantly different with the relative content of gold and sulfide symbiosis. (See Table 1)
Table 1 Effect of symbiotic relationship of gold in a small amount of sulfide quartz vein containing gold ore on the floatability of ore
Ore type | Ore characteristics | Gold ruler (mm) | Gold in sulfide content (%) | Gold content in quartz (%) | Grinding fineness (%-200 mesh) | Processing flow | Gold recovery rate (%) |
1 | Gold and quartz are closely related | 0.012 (average) | 32 | 68 | >90 | Multi-stage grinding | ~90 |
2 | Gold and sulphide are closely related | 0.010 (average) | 58 | 42 | 60 | Flotation | ～96 |
It can be seen from Table 1 that the gold content of the two ores is relatively fine. The ore 1 is treated by fine grinding and multi-stage sorting process, and the recovery rate is only 90%. The ore 2 grinding fineness is coarse, the sorting process is simple, and the recovery rate is 96%. In order to prove that the ore 1 is difficult to select, the ore 2 good selection has to be further analyzed from the gold production status of the grinding products. It can be seen from Table 1 that the fineness of the grinding of the two ores has not reached the extent of dissociating the gold particles. Only a part of the gold in the grinding product exists in a monomer free state. Most of them are in a state of being in a living state with quartz and iron sulfide. Free monomer gold is easy to float, while continuous gold is dependent on the floatability of the minerals that symbiotic with it. It is obvious that the gold ratio of the sulphide to the sulphide is important to the quartz, so when the ore 2 is treated, the fineness of the grinding can ensure that the gold is floating as long as the sulphide mineral crystal particles are dissociated. A more adequate recovery is obtained during the selection process. Therefore, in order to increase the recovery rate of gold in ore 1, fine grinding must be carried out to maximize the monomer dissociation of the gold particles. However, fine grinding is limited by many technical and economic conditions. Sometimes even fine grinding can not completely expose the gold particles, and the grinding power is expensive and uneconomical. In addition, fine grinding can cause muddy and over-grinding, which affects the flotation effect and concentrate dehydration. The following describes the flotation characteristics of these two ores and the technical measures to strengthen the selection process.
1. Ore that is closely related to sulphide ore
The ore is relatively simple in composition, pyrite is the most important metal sulfide, and other sulfides such as Cu, Pb, Zn, and Bi are rare. The relative content of natural gold in pyrite is above 60%, and the remaining gold is present in gangue minerals such as quartz and other metal sulfides. This type of ore is most suitable for treatment by flotation. Originally, the floatability of heavy metal sulfides was better, and the natural gold was closely symbiotic with it, which further improved the floatability of the sulfide minerals in the ore. Therefore, the use of flotation method to deal with such ore selection indicators is relatively high, up to 90% to 96%.
If the part of gold produced in the gangue is very fine, the degree of dissociation of the monomer after grinding is not high, which will inevitably affect the sorting effect, so that a part of the gold is lost from the tailings. In this case, it is possible to enhance the sorting process by increasing the fineness of the grinding and prolonging the flotation time. If the loss is severe, the flotation tailings can be cyanidated. [next]
When the grinding product contains coarse-grained free gold, it should be added with mercury or re-election before the flotation. Re-election methods include jigging, chutes, shakers, and the like. Among them, the jigging application is more extensive. Under normal circumstances, for quartz veins containing coarse particles of free gold, gold ore is used, and the refinery concentrate with a recovery rate of 50% or more can be obtained by treating the grinding products with a jig. For the ore with fine gold inlays that contain no or only a small amount of coarse gold, the jig is used, and the recovery rate is not high, only about 20%.
2. Ore that is closely related to quartz
The main feature of this ore is that the metal sulfide content is low, and more than 70% of natural gold is symbiotic with quartz. The metal minerals in the ore are mainly pyrite. Addition to a small brass ore, pyrrhotite, bismuthinite, galena, which also contain arsenic, antimony, clay, and carbon species. More suitable for full mud cyanidation. When the content of coarse gold is large, the mercury is pre-mixed, the recovery rate of the operation can reach 70%-80%, and the total recovery rate of the mercury-mixed tailings cyanide treatment can reach 96%-98%.
When the gold particles in the ore are unevenly embedded, the fine particles are mostly, and when the ore grade is low, the cyanidation or flotation method can be directly used. Since the ore is more difficult to select, the flotation method must take effective measures to strengthen the sorting process from the aspects of process flow, operating conditions, and pharmaceutical system. Otherwise, the selection effect is low and the tailings cannot be discarded. Production practices show that the following technical measures are more effective in strengthening the selection process of difficult-to-select gold-bearing quartz veins.
(1) The original ore is hand-selected to remove large blocks of surrounding rock that meet the grade of abandoned tailings, and to improve the grade of ore entering the flotation operation.
(2) Emphasis on the pharmaceutical system. Using strong strong collector flotation agent (butyl xanthate, amyl xanthate) appropriate to increase the amount of reagent (xanthate amount of up to 150 ~ 200g / t), and mixing medication, with foaming ability using capture The collection process and the addition of some of the ingredients to the ball mill enhance the selection process.
(3) The flotation process in the stage grinding stage is adopted, and the particle size selection can be carried out to reduce mud formation, prevent over-grinding, and ensure effective recovery of different grain-level gold.
(4) Add intermediate sorting operations (amalgamation, re-election, etc.) in the first stage of the grinding classification circuit.
(5) The last section of the sweeping tailings can be classified by a hydrocyclone, overflowed and discarded, and the coarse sand after enrichment is re-grinded and re-selected. Since the gold encapsulated in the gangue is further dissociated by re-grinding, most of it can be recovered by re-selection.
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