Discovery of gypsum in Lanping lead-zinc ore and its influence on beneficiation process

Lanping lead-zinc mine is currently China has the largest proven reserves of lead-zinc deposits, with a shallow, high-grade metal features. However, because the oxidized ore on the lead-zinc deposit is very difficult to choose, and the problem of ore dressing for lead-zinc ore has not been solved for a long time, the upper oxidized ore cannot be exploited, the deep sulphide ore is easy to be selected, the economic value is high, and the It is difficult to mine, so as to affect the development and utilization of the mine. Since the 1980s, a number of institutions have conducted research on process mineralogy and beneficiation of the Lanping refractory lead-zinc mine. The existing research suggests that the main reason for the difficulty in selecting the Lanping lead-zinc mine is the fine granularity of useful minerals. Weathering and muddy are serious. Our experimental study found that the main reason for the difficulty in selecting Lanping Oxide Lead-Zinc Mine is that the useful mineral inlays are fine in size, and the weathering and muddy are serious. Our experimental research found that the reason for the difficulty in selecting Lanping Oxide Lead-Zinc Mine is related to the weathering and mud formation of ore. However, the presence of soluble gypsum interferes with the fluidization of zinc oxide, which is difficult to select and industrialize Lanping sulfur oxide. An important reason for the difficulty of production.

First, the nature of the ore

The Lanping lead-zinc deposit is divided into two types of limestone type and sandstone type. The mineral composition of different types of ore is basically the same, and only the quantity of each mineral is different. The relative contents of the main minerals of the two ore samples are shown in Table 1.

Table 1 Relative content of main minerals in two ore samples/%

The Lanping Oxide Lead-Zinc Mine Sandstone and Limestone have the same mineral type. The lead-zinc sulfide mineral is galena and sphalerite, and the lead-zinc oxide mineral is leucite, lead bismuth, diabase, and Polar ore and a small amount of water zinc ore, iron minerals such as pyrite, pyrite, arsenopyrite, limonite, hematite, gangue minerals, sulfate mineral barite , lapis lazuli, Shihao, carbonated Salt minerals include calcite and dolomite. However, it is worth noting that sandstone-type ores have a small amount of natural sulfur . The presence of natural sulfur has some interference with the selection of lead sulfide concentrates, while natural sulfur is not found in limestone ores.

Although the minerals of the two ores are the same, the quantity of each mineral is quite different. The sandstone type ore has low lead and zinc content, especially the low lead content. The galena and white lead ore have less minerals, while pyrite and white. The number of iron ore is very large, especially in the case of pyrite and pyrite dispersed in sphalerite, smithsonite and calcite in micro-grain, which interferes greatly with the selection of lead-zinc ore.

The embedding state of lead and zinc and various iron minerals is more complicated, and the lead-zinc sulfide minerals are closely related to pyrite and arsenopyrite. In the present ore, the zinc-oxidized mineral zonons and the heterogeneous relationship between the heteropolar ore and the limonite are more complicated, and the complex state of the shell-like, disseminated, and the like is often distributed in the limonite, and the two are associated with each other. Even in the magnesite of the microcrystalline aggregate, dusty limonite is distributed between the crystal grains.

The ratio of lead sulfide to lead oxide in sandstone-type ore is about 1:2, and the ratio of sphalerite, smithsonite and heteropolar ore is almost 1:1:1. The mineral proportion of lead-lead and lead oxide in limestone ore is similar to that of sandstone-type ore, which is about 1:2, similar to sandstone-type ore, and the ratio of sphalerite, smithsonite, and heteropolar ore to sandstone-type ore. Larger, approximately 1:3:1. That is, the proportion of limestone-type ore whip-zinc mine is relatively large, and the proportion of sandstone-type ore is difficult to select zinc oxide heteropolar ore.

The pale-colored sphalerite and smithsonite in the Lanping Oxide Lead-Zinc Mine are unique compared with the sphalerite and smithsonite from other producing areas. The light-colored sphalerite is almost colorless and transparent, and contains no iron. It is closely symbiotic with limonite and contains varying amounts of iron. Most of the rhombohedral aggregates are micro-grain-like aggregates with fine crystals and weak luster on the mineral surface, showing a glassy luster similar to water. Generally, the weaker the gloss, the more mineral ionic bond components, the less covalent bond components, the stronger the hydrophilicity of the minerals with weaker gloss.

During the mineral identification process, a small amount of gypsum was found in both sandstone-type ore and limestone ore, but the amount, solubility and influence of gypsum on the mineral sorting need to be further studied.

Second, the ore salt soluble salt leaching test

During the flotation test of the Lanping Oxide Lead-Zinc Mine, it was found that the weight of each product after flotation was less than the weight of the ore, and the zinc oxide mineral was extremely difficult to vulcanize, requiring the addition of a large amount of sodium sulfide. Soluble salts are present in the ore. The yield of the leachate in the samples from 2003 and 2004 was determined separately. 100 g of each ore sample was taken, and distilled water was statically leached for 24 hours, and the immersion liquid was separated by filter paper. The results of the leaching test are shown in Table 2. The soluble salts are crystallized in the filtrate of each ore sample, especially in 2004.

Table 2 Leaching results of soluble salts in ore

Third, soluble salt detection

Because of the above-mentioned several ore samples, the sandstone-type ore has a large amount of soluble matter. Therefore, the sandstone ore leaching liquids in 2003 and 2004 are separately evaporated to dryness, and the obtained crystals are determined by electron probe spectroscopy, as shown in Fig. 1 and 2, it can be seen that the main chemical component of the leachate is Ca. As shown in Fig. 1 and Fig. 2, it can be seen that the main chemical component Ca of the leachate is S, trace amounts of Cl, P, Na, Mg and the like.

The X-ray diffraction method is the most effective means for detecting crystals, so the composition of the extract was measured by X-ray diffraction, and it was found that the extract was gypsum. However, in 2003, the sandstone extract was 0.15 crystallized gypsum, while in 2004 the sandstone extract was dihydrate gypsum. (See Figure 3, Figure 4)

Fourth, the results of the discussion

The results of the leaching test and the test of the leaching materials show that, for example, the soluble salt-gypsum is present in each mineral sample of the Lanping lead-zinc mine, but the amount of gypsum in the ore sample in 2003 is less than that of the 2004 sample; Second, inclusive of a small amount of phosphorus, but the 2004 sandstone apparently containing a soluble salt of magnesium and chloride ions of soluble salts sandstones 2003 and 2004.

The difficulty in beneficiation of Lanping Oxide Lead-Zinc Mine is that it is difficult to be vulcanized. The amount of fluidized sodium in the beneficiation process is very large. This is mainly due to the presence of soluble salt-gypsum. After grinding and stirring, the pulp contains a lot of calcium ions. Calcium ions are more active than lead and zinc ions, and calcium sulfide in the addition of sodium sulfide preferentially forms calcium sulfide, which interferes with the formation of zinc sulfide on the surface of zinc oxide minerals, thus affecting the zinc oxide minerals to be captured by xanthate.

According to the results of this study, our institute adopted pretreatment measures for the small ore dressing test of the Lanping lead-zinc mine to separate most of the gypsum from the slurry. After pretreatment, the amount of sodium sulfide in the zinc oxide flotation process is greatly reduced, and the effect of zinc oxide flotation is significantly improved. Obviously, the reason why the Lanping Oxide Lead-Zinc Mine is difficult to choose is of course related to the weathering and muddy of the ore. The presence of soluble gypsum interferes with the fluidization of zinc oxide, which is the root cause of the difficulty in controlling the Lanping Oxidation Mine and the difficulty in industrial production. .

Liang Kezhi He Xiaojuan Tu Xiaoping Li Bo