Conventional flotation of lead-zinc oxide ore and its mixed ore

1. Lead oxide minerals and flotation method thereof

Industrially important lead oxide minerals are mainly white lead ore ( PbCO ₃ , containing 77.6% lead , density 6.5g /cm ³ , hardness 3 ) and lead bismuth ( PbSO ₄ , lead 68.3 , density 6.3g /cm ³ , hardness 3 ). Both minerals can be vulcanized, so vulcanization flotation is commonly used in flotation. The lead oxide ore is vulcanized and then treated with xanthate or black medicine as a collector . Generally, the advanced xanthate is better. Before vulcanization usually first treated by desliming, off clay, iron hydroxide and other argillaceous substances. But off the mud can cause metal loss, can also be processed without desliming, add water glass and other dispersants to eliminate the harmful effects of sludge. The vulcanizing agent is sodium sulfide or sodium hydrosulfide. Excess sodium sulfide has an inhibitory effect on leucite, lead bismuth and galena. Practice has shown that the suitable pH value of white lead ore vulcanization is 9~10 . Excessive Ns ₂ causes the pH value to be too high, which will produce colloidal lead sulfide which is easy to fall off from the mineral surface, thereby reducing the vulcanization effect. In practice, in order to reduce the pH value during vulcanization , sometimes adding a portion of sodium hydrosulfide instead of sodium sulfide, or adding ammonium sulfate, sulfuric acid, etc., can also accelerate the vulcanization rate and improve the flotation index. There are two ways to add the vulcanizing agent, that is, one-time addition or batch addition, which is generally determined by experiments.

2. Zinc oxide mineral and its flotation method

The main zinc oxide minerals are smithsonite ( ZnCO ₃ , containing 52% zinc , density 4.3g /cm ³ , hardness 5 ) and heteropolar ore ( H ₂ Zn ₂ SiO ₅ , containing 54% zinc , density 3.3~ 3.6g /cm ³ , hardness 4.5~5.0 ).

There are two main methods for the application of zinc oxide ore flotation in the industry:

1 warming vulcanization flotation method - zinc oxide minerals can form zinc sulfide colloidal precipitate at room temperature, but it is not easy to fix on its surface. Need to heat the slurry to 60~ 7 0 °C Then vulcanized sodium sulfide, zinc sulfide thin film generating surface of zinc oxide, copper sulfate activated after vulcanization, plus xanthate flotation. This method is mainly used for flotation of smithsonite and flotation of heteropolar ore, but the effect is poor.

â‘¡ aliphatic amine flotation --- i.e., at room temperature, with sodium sulphide adjusting the pulp pH value of 10.5 to 11, and then with a cationic collector aliphatic amine flotation first zinc oxide. This method has good flotation effect on rhombohedrite and heteropolar ore. The method is characterized in that sodium sulfide is only used for the adjustment of the pH value of the slurry , and the excess sodium sulfide has no inhibitory effect. Therefore, after the addition of sodium sulfide, the collector flotation can be added without a certain stirring time. However, when the amine salt is used for flotation, the slime has a significant effect, because the slime can adsorb a large amount of amine chemicals and can adhere to the mineral surface, so that the selectivity of the flotation process is greatly reduced. Therefore, pre-desilting must be carried out to eliminate the effects of slime. Phosphorus may also be sodium hexametaphosphate dispersing sludge and water glass, sodium sulfide and amine 1: 50 formulated emulsion flotation, desliming job cancel previously, to achieve good flotation.

3. Sorting order of lead-zinc mixed ore

For ores with both lead-zinc sulfide minerals and lead-zinc oxide minerals, the process of selecting the sulfide minerals and then selecting the oxidized minerals is adopted, that is, the order of sulfide minerals (mixed flotation or preferential flotation)-lead oxide-zinc oxide Flotation. In practice, there is also a process of selecting lead after zinc is selected, that is, the process of selecting lead sulfide, lead oxide, and then zinc sulfide and zinc oxide. The former is the first sulfur post-oxygen process, and the latter is the lead-and-zinc process.

When zinc oxide is floated with a fatty amine, zinc sulfide can also float well, so when the ore has a high oxidation rate and there is not much zinc sulfide, it can be recovered simultaneously with an amine. The order of ore sorting shall be determined according to the characteristics of the ore after testing.

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