Beneficiation technology of different types of lead-zinc ores

Lead-zinc metals are widely used in electrical, mechanical, military, metallurgical, chemical and other fields. With the increasing demand for metals year by year, it is urgent to improve the recovery rate of metal ores in ores. Oxidized lead-zinc ores can be divided into three types according to the degree of oxidation: sulfide lead-zinc ores, oxidized lead-zinc ores and mixed lead-zinc ores. Among them, sulfide lead-zinc ores and mixed lead-zinc ores can be treated by flotation, while oxidized lead-zinc ores need to be treated by flotation in addition to beneficiation metallurgy or single metallurgy due to their fast oxidation rate, high mud content and close symbiosis with limonite. The following will introduce the above three beneficiation technology of lead-zinc ores respectively.

011. Ore dressing process of lead-zinc sulfide ore

The main mineral components of lead-zinc sulfide ore are galena and sphalerite. Its flotation process can be divided into three types: priority flotation, mixed flotation and uniform flotation. Most lead-zinc sulfide ores choose to adopt the priority flotation process, first suppressing zinc ore and then floating lead ore. The main reason for adopting "floating lead and suppressing zinc" is that galena has good floatability and is not easy to activate after suppression. In addition, the zinc content in most lead-zinc sulfide ores is higher than the lead content. According to the principle of "less floating and more suppression", it is conducive to economic rationality.

022. Oxidized lead-zinc ore dressing process

For the flotation of oxidized lead-zinc ore, it can be divided into the selection of oxidized lead ore and oxidized zinc ore. The oxidized lead ore is generally selected by the sulfide xanthate flotation method, and the oxidized zinc ore is generally selected by the sulfide amine flotation technology.

Oxidized lead ore dressing

Oxidized lead ore dressing methods can be divided into single flotation, gravity separation, combined flotation and metallurgy. Oxidized lead ore can be divided into two categories: easy to select and difficult to select. Among them, for easy-to-select lead oxide ores, single flotation and gravity separation + flotation combined beneficiation methods can be used. Flotation methods can be sulfide flotation and fatty acid flotation, and the former is often used. If the ore contains lead alum and the properties of the gangue minerals are relatively complex, heavy liquid separation can be used to prove that gravity separation can obtain lead concentrate. For gravity separation and muddy parts, metallurgical methods can be considered. When iron hydroxide is the main gangue mineral in difficult-to-select lead oxide ores, and most of the lead is tightly combined with iron hydroxide, it is necessary to first find out which part of the lead is associated with iron ochre and which part is a separate mineral. In addition to phase analysis, gravity separation, magnetic separation and other methods are also required to separate iron minerals from gangue minerals.  

Oxidized Zinc Ore Beneficiation: When zinc exists in the form of a single mineral, it can be recovered by flotation. There are four available flotation methods. One is the heating sulfidation method, which is mainly suitable for the treatment of smithsonite. The slurry is heated to about 70°C, sodium sulfide and copper sulfate are added for sulfidation activation, and then high-grade xanthate is used as a collector for flotation; second, the fatty acid reverse flotation method is mostly used to treat dolomitized limestone containing a small amount of silicate and iron oxide in the gangue minerals. During the operation, sodium fluoride is first used to inhibit smithsonite, and then oleic acid is used as a collector to separate gangue minerals from smithsonite; thirdly, the fatty acid positive flotation method is to use sodium hydroxide and water glass to inhibit silicate and iron oxides, citric acid to inhibit alkaline earth metal carbonates, and then oleic acid is used as a collector to float smithsonite; fourthly, the amine method is to add sodium sulfide to the raw ore for sulfidation at room temperature after desludging. Subsequently, the zinc oxide mineral is floated in the alkaline ore pulp with a primary amine collector with a carbon chain length of 8 to 18.

033. Mixed lead-zinc ore dressing process

The flotation method of mixed lead-zinc ore can be selected according to the characteristics of sulfide ore and oxide ore, but the appropriate flotation order needs to be determined. Common flotation schemes are: lead sulfide-lead oxide-zinc sulfide-zinc oxide or lead sulfide-zinc sulfide-lead oxide-zinc oxide. When the lead oxide content is low, the first option is usually selected; if the lead oxide content is high, the second option is better.

As can be seen from the above, flotation is the main beneficiation method for lead-zinc ore. A combined process of flotation after gravity separation can also be used, supplemented by metallurgical methods to recover metals. For example, after obtaining low-grade lead-zinc concentrate through beneficiation, the metal is further extracted through sulfuric acid leaching, purification and other processes. In addition to the above flotation processes, a series of innovative flotation processes have been developed in actual production, such as equal flotation, branch series flotation, etc., which are widely used in actual beneficiation.