The nature of the ore mainly refers to the mineral composition in the ore, the content and proportion of various minerals, the intergrowth characteristics of useful minerals and the symbiosis characteristics between minerals, the isomorphic impurities in the ore, and the existence form of the mineral (if it is primary Mineral or secondary ore, sulfide ore or oxide ore, etc.), as well as the content and composition of soluble salts, etc., all affect the flotation process of minerals.
The same mineral and minerals of similar composition from different origins often have different floatability. For example, the floatability of galena or sphalerite collected from different producing areas is very different, especially the different colors of sphalerite (related to the amount of impurities such as iron and cadmium) are more prominent. The floatability of apatite, calcite or barite produced in the production area is also very different. The reason for this phenomenon is mainly related to the conditions for the production of minerals and the entry of impurities into the minerals in the same way. In addition, during the mining, transportation and storage of ore, the floatability of the mineral may also change due to the oxidation of the mineral surface and the contamination of impurities.
The formation conditions of useful minerals affect the structure of minerals and have a strong influence on the floatability of minerals. Sulfide minerals generated under high pressure and high temperature conditions, such as those separated from molten magma or precipitated from hydrothermal fluids, usually have a relatively compact structure with no pores in between, and the geometric size of mineral crystals is relatively large.
The sequence of mineral formation can have an important impact on flotation. When there are cracks in the minerals formed earlier, they are often filled with minerals formed later to become vein-like or net-like structures. In the process of crushing and grinding, new fracture surfaces often appear along the fine mesh veins of the ore, and the secondary minerals are more prone to sludge.
During the mineralization process, secondary enrichment sometimes occurs, that is, after some primary sulfide minerals interact with other metal salt solutions, they precipitate to form a rich ore zone at the contact between the oxide ore and the primary sulfide ore. Due to secondary enrichment, films with different compositions are often formed on the surface of primary sulfide minerals. A typical example is that the surface of pyrite is covered with chalcocite or copper blue film; it is also common that the surface of chalcopyrite is covered with copper blue, and the surface of sphalerite is covered by silverite film. Obviously, in the process of crushing and grinding, it is very difficult to completely separate the covering film on the surface of the mineral from the mineral, which results in the mineral having the floatability similar to the covering film.
It should be pointed out that the following two changes have a particularly large impact on the flotation properties of minerals: one is silicification; the other is kaolinization, chloriteization and sericitization.
In the first case, the minerals are glued by silica; in the second case, many very different microcrystalline minerals are formed, which will produce a large amount of fine mud during the grinding process.
Different types of symbiotic minerals, the degree of difficulty of flotation separation is also very different, because in flotation separation, not only one or several minerals are easy to float into the foam product, but also other minerals that should not float. Ease of control. For example, there is no difficulty in using fatty acid collectors to float scheelite from quartz, but if the gangue is calcite, fluorite or dolomite, the flotation separation is very complicated; sulfur compounds are used from non-sulfide minerals It is also relatively simple for collectors to surface sulfide minerals, but it is much more difficult to separate concentrated sulfide minerals or partially oxidized sulfide minerals from each other.
The nature of the ore is an objective factor that is difficult to change, so corresponding technological measures must be taken in the practice of flotation production to adapt to the nature of the ore and its changing law. In order to establish a relatively stable process operation system and obtain a relatively stable flotation index, the ore entering the concentrator should be relatively stable in nature to facilitate management. This often requires the cooperation of mining and beneficiation workers. Can be achieved. For example, before blasting, some mines first sample and analyze the ore in each pit and face each face, to roughly find out the grade and composition of the ore blasted from each face, and then according to each face Proper ore blending is performed in proportion to the number of ore produced. Some mines are equipped with special ore blending sites to maintain the relatively stable nature of the ore beneficiation process; some concentrators also perform ore blending by feeding and unloading during the crushing process; In other dressing plants, the grinding products are mixed through a public thickener to mix the grinding products of the whole field, and remove excess water or fine mud, so that the feed concentration of the flotation operation is also relatively stable.
The choice of flotation process depends on the particle size and sludge characteristics of the useful minerals in the ore.
There are five types of inlay granularity: coarse-grained inlay, fine-grained uniform inlay, uneven in thickness, complex uneven inlay, and aggregate inlay. For coarse-grained embedded ore, because the particle size of the embedded cloth is coarse, it is easy to separate useful minerals from the gangue. It is advisable to use the two-stage flotation principle process of regrinding the medium ore; Coarse grains and fine grains. In one stage, part of the coarse-grained qualified concentrate can be obtained, and the fine-grained contiguous body is reground and re-selected. It is advisable to use the two-stage flotation principle process or the three-stage flotation principle process of the tailings regrind; Evenly embedded ore, because the particle size of the embedded ore is extremely uneven, and the dissociation range is very wide, it is appropriate to use the three-stage flotation principle process; the aggregate embedded ore, because the useful minerals are contained in a larger aggregate, during rough grinding It is easy to separate the aggregate from the gangue. It is advisable to use the two-stage flotation principle process of regrinding the two ends of the coarse concentrate (ie aggregate) or the two-stage flotation principle of regrinding the middle ore.
When selecting a multi-metal flotation process, in addition to considering the influence of the particle size characteristics of the embedded cloth on the process, attention should also be paid to the influence of the floatability of various minerals and other factors on the process selection.
For three types of ores such as high grade of raw ore, low gangue content, coarse-grained distribution, or simple ore properties, large difference in the floatability of useful minerals, easy separation, or containing a large amount of dense polymetallic sulfide ore, direct priority should be used The principle flow of flotation; for the ore with medium grade of raw ore, or poor and coarse aggregates, or ore containing a small amount of polymetallic sulfide ore, it is advisable to use the principle flow of full mixed flotation; for the complex polymetallic ore with “equal floatability”, It is advisable to use part of the mixed flotation principle process.