On the role of aluminum salt in the flotation, there are many reports in the literature, but research on effects of aluminum salts of rare earth mineral flotation are few. At the same time, due to the complexity of the behavior of aluminum salts in the pulp, their flotation mechanism is also well studied, and it is necessary to continue to accumulate data.
In this section, the effects of aluminum salt and its sharing with water glass on the flotation of rare earth minerals are studied, and the mechanism of action is explored.
Test Results and Discussion 1. First, aluminum nitrate and studied alum bastnaesite different particle sizes, the influence of calcium and fluorocarbon cerium monazite ore flotation. The test results show that with sodium oleate as the collector , the recovery rate of the three minerals decreases sharply with the increase of the concentration of aluminum salt. This indicates that the aluminum salt is a strong inhibitor of bastnasite, monazite, and fluorocarbon strontium ore.
Next, in the rare earth minerals, artifacts hematite, calcite, fluorite flotation, respectively, aluminum nitrate, aluminum sulfate and alum were tested, the results showed that four mineral aluminum nitrate according to the following order of magnitude of inhibition arrangement : Rare earth minerals > illusion hematite > calcite > fluorite. In fact, there is no significant inhibition of fluorite in the range of 1000 g/t (see Figure 1). Aluminum sulfate and alum also have selective inhibition, but the inhibition of rare earth minerals by aluminum sulfate is not as strong as that of aluminum nitrate (see Figure 2 and Figure 3). The mineral size is: -0.043+0.01mm, oxidized paraffin The amount of sodium soap added is (g/t): floating mixed rare earth 200, imaginary hematite 500, fluorite 100-150, calcite 500, barite 500.
Fig.1 Effect of aluminum nitrate on mineral flotation I-rare earth minerals; II-fluorite; III-artificial hematite; IV-calcite
Fig. 2 Effect of aluminum sulfate on mineral flotation I-rare earth minerals; II-fluorite; III-artificial hematite [next
Fig. 3 Effect of alum on mineral flotation I-rare earth minerals; II-fluorite; III-artificial hematite; IV-calcite (CaCO 3 ) V-barite (BaSO 4 )
When aluminum salt and water glass are used together, the suppression effect can be remarkably improved. It can be clearly seen from the results of the first group of Table 1 that, in the case where the total amount of the agent is the same, the inhibitory effect on the mixed rare earth mineral is stronger when used alone than when used alone. Especially in the case of excessive collector, the effect is more prominent. The second group of results shows that, in the case where the amount of addition alone is quite large and difficult to work, the mixed use has a strong inhibitory effect, and the total amount can be reduced by more than half. . Moreover, adding water glass first is better than adding lead nitrate first. The third group of results showed that increasing the pH value of the slurry is also a way to make the aluminum nitrate still strongly inhibit the rare earth minerals in the case of excess collector.
Experimental grouping | Aluminum nitrate (g/t) | Water glass (g/t) | Sodium laurate (g/t) | Pre-mineral aqueous solution pH | Recovery rate (%) |
A group Two groups Three groups | 0 100 500 0 50 0 3000 0 200 (post plus) 2000 (post plus) 3000 3000 | 0 0 0 100 50 0 0 800 200 200 0 0 | 200 200 200 200 200 800 800 800 800 800 800 800 | 6.8 6.8 6.8 6.8 6.8 6.8 6.8 6.8 6.8 6.8 10.6 11.0 | 100 32.5 0 20.3 0 100 100 40.7 0 42.0 0 0 |
Table 2 Ore flotation results with alum instead of dextrin
Inhibitor | Dosage (g/t) | Yield (%) | Fluorite concentrate grade (%) | Fluorite concentrate recovery rate (%) | ||||
Fe | F | RE x O r | Fe | F | RE x O r | |||
Fine paste alum | 1500 2500 | 27.76 26.89 | 18.45 17.54 | 27.15 27.30 | 4.43 3.05 | 10.5 9.3 | 88.9 87.2 | 37.8 26.4 |
Note: RExOy - rare earth oxide
When alum is used instead of dextrin (both shared with water glass), the content of rare earth in fluorite concentrate is significantly reduced when the grade and recovery of fluorite are very similar. The above results have been successfully applied to the preferential flotation fluorite process for the reduction of roasting magnetic separation tailings and are used for design and construction.
1) Effect of pH value of pulp on inhibition of aluminum salt
As shown in Figure 4 (Comparative Table 3, the inhibition of monazite by aluminum nitrate in the acidic pulp (pH 3.4), but caused activation; the inhibition of bastnasite is the strongest in distilled water, strong acid The strong alkali slurry is not weakened; the case of fluorocarbon calcium strontium ore is completely opposite (Fig. 5), and the weakest acid or neutral is the weakest. In the strong acid medium, the fluorocarbon strontium ore is almost completely Loss of floating ability. It can be seen that the pulp, pH value has a great influence on the inhibition of aluminum nitrate, and it varies greatly depending on the nature of the mineral.
Fig. 4 Effect of pH value of pulp on inhibition of aluminum nitrate I-fluorocarbon antimony ore; II-monaz
Table 3 Relationship between the pH of the added solution and the pH of the slurry
The pH of the solution before the mineral is added | 2.8 | 5.5 | 6.6 | 7.4 | 8.1 | 9.0 | |
Pulp pH | Bastnasite (I) Monazite (II) | 3.2 3.4 | 7.4 7.5 | 7.5 7.9 | 7.8 8.3 | 8.1 8.5 | 9.0 9.0 |
In addition, an interesting phenomenon has emerged. In the above-mentioned experiment of adding three kinds of aluminum salts, the pH values ​​of the mixed rare earth minerals, the pseudo-hematite and the fluorite were measured respectively, and it was found that there is a common law, that is, under the condition of distilled water, the rare earth minerals and the red iron The best inhibitory effect of the ore is that the amount of aluminum added is just enough to reduce the pH of the slurry to 5.7-6.5. However, the three aluminum salts have little effect on the pH of the fluorite slurry, always within the range of 7-7.6. Fluctuations, fluctuations in flotation yields are also small.
2) Effect on the adhesion rate of the ore particles to the bubble Figure 6 shows that the effect of aluminum nitrate on the adhesion time of the rare earth mineral particles to the bubbles is consistent with their actual flotation. With the increase of the concentration of aluminum nitrate, the time for the rare earth ore particles to adhere to the bubbles is sharply lengthened. Whether it is first added with a collector or mixed with a collector before being added to the slurry, it can show that the aluminum nitrate bubbles are formed in each part. The adhesion time is extended, but it is not as strong as adding aluminum nitrate first. In the figure, 1 is sodium laurate (post-added aluminum nitrate), 2 is sodium laurate and aluminum nitrate pre-mixed and then added, 3 is sodium laurate (first added aluminum nitrate), 4 is sodium oxidized paraffin (first added aluminum nitrate) ). In the test, oxidized paraffin sodium soap 20 mg/L, sodium laurate 50 mg/L, and mineral particle size of -0.15+0.074 mm were added.
Figure 6 Effect of aluminum nitrate concentration on mineral attachment time [next]
3) Effect of aluminum on the adsorption amount of excess sodium laurate (14C) on minerals
In order to find out the reason why aluminum nitrate no longer inhibits rare earth minerals under the excess collector, the aluminum nitrate is studied in rare earth minerals with granular sodium laurate with radioisotope 14C under the condition of 400mg/L collector. The effect of the surface adsorption amount is -0.043 + 0.01 mm. Figure 7 shows that under this condition, the adsorption amount of sodium laurate (14C) on the surface of rare earth minerals increases with the increase of the concentration of aluminum nitrate, resulting in a sharp increase in the hydrophobicity of the mineral surface.
Fig. 7 Effect of aluminum nitrate on the adsorption capacity of sodium laurate (14C) on minerals
4) Inhibition mechanism (1) The aluminum salt is hydrolyzed in water to form a slightly soluble and rarely dissociated aluminum hydroxide and an easily dissociable acid. When the hydrolyzed and dissociated products reach a certain amount, they are adsorbed to the surface of the rare earth mineral. The latter causes strong hydrophilicity, prevents the collector from adsorbing to the surface of the mineral, and can also squeeze out the collector pre-fixed on the surface of the rare earth mineral, thereby determining the stability of the interface liquid layer when the particle approaches the bubble. This causes the adhesion to be drastically slowed down or stopped (according to the experimental results of Fig. 6) and the flotation of rare earth minerals is suppressed.
(2) In alkaline pulp (pH 7.4-9.0), aluminum nitrate can strongly inhibit monazite. In weak alkaline pulp (pH 7.4-7.5), aluminum nitrate is most effective in suppressing bastnasite. According to chemical studies, under the above conditions, mainly Al(OH) 3 , OH - and AlO 2 - are active. The inhibition of fluorocarbon calcium strontium ore is prominent in strong acid pulp (or strong alkaline), the effective components should be Al 3+ and H + or AlO 2 - and OH - in different pH pulp, aluminum salt to three rare earths The role of minerals is very different and selective inhibition of rare earth minerals, imaginary hematite and fluorite is unclear.
(3) Excess collector can cause the aluminum salt to lose its inhibitory ability and even activate. This may be due to the increase of the amount of sodium laurate combined with aluminum ions into aluminum laurate, thus increasing the hydrophobicity of the mineral surface. The flocculation of a large amount of aluminum salt is beneficial to the adsorption of sodium laurate, and a large number of fine-grained rare earth minerals are agglomerated together and attached to the bubbles to rise. Therefore, the flotation speed increases and the foam is very stable. However, when the slurry is strongly alkaline, the rare earth mineral is re-inhibited due to the increased solubility of the colloidal aluminum hydroxide. Since the water glass has a dispersion effect, it helps to eliminate the flocculation phenomenon, and the same result can be obtained.
2. Conclusions (1) Aluminum salt is a strong inhibitor of rare earth minerals, imaginary hematite, barite and calcite. It has no obvious inhibitory effect on fluorite and can be used as a selective inhibitor of fluorite separation from these minerals. Aluminum salt and water glass are shared, and the suppression effect is better.
(2) The pH value of the pulp has a great influence on the inhibition of aluminum salt. The aluminum salt strongly inhibits the fluorocarbon calcium strontium ore in the strong acid ore, and the living monazite and bastnasite; in the strong alkaline ore, it can strengthen the inhibition of monazite and fluorocarbon strontium ore; In the alkaline medium, the inhibition of monazite and bastnasite is enhanced, and the fluorocarbon calcium strontium ore is activated.
(3) Since the aluminum salt is hydrolyzed and dissociated in the slurry to form products such as Al 3+ , AlO 2 - , Al(OH) 3 , H + , OH - , which adsorb to the surface of the mineral, hindering the adsorption of the collector, and The pre-adsorbed collector can be squeezed out, resulting in a decrease in the floatability of the mineral.
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