Flotation process of carbon-containing fine-grained lead-zinc ore

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Lead-zinc ore is one of the important mineral resources for the development of the national economy. With the large-scale mining of easy-to-select and rich ores, it has been gradually exhausted. Now the difficult-to-select lead-zinc ore has become the focus of people's development. So how to select the difficult-to-select fine-grained lead-zinc ore? This article takes a fine-grained lead-zinc ore as an example to introduce its lead-zinc ore dressing process.

Ore properties of carbon-containing fine-grained lead-zinc ore

The main valuable metal elements in the original ore are zinc (sphalerite) and lead (galena). The carbon content in the mineral is very high, which belongs to the carbon-containing lead-zinc ore. The content of other metal minerals is low. Among them, the embedded particle size of sphalerite in the ore is relatively coarse, and its composition basically does not contain iron. Coarse-grained sphalerite is wrapped with fine-grained gangue minerals, galena, organic carbon and some other minerals. Galena is embedded in sphalerite in the form of inclusions along the sphalerite cracks or in the sphalerite. The embedded particles are fine and not easy to dissociate into monomers.

In addition, organic carbon in the ore is embedded in the cracks of coarse-grained sphalerite or embedded in the sphalerite periphery in the form of fine-grained and fine-grained inclusions. In addition, a small amount of organic carbon is embedded in sphalerite in the form of fine-grained and fine-grained inclusions. It is difficult for some organic carbon to fully dissociate from sphalerite during grinding. And the symbiotic relationship between galena and sphalerite is very close. Irregular galena is often embedded in coarse sphalerite, some fine galena is embedded in fine particles, and some coarse particles are often wrapped with fine sphalerite; or fine and micro-fine galena is embedded in sphalerite in the form of inclusions. Therefore, some organic carbon and galena are difficult to fully dissociate from sphalerite, resulting in separation difficulties.

Process determination of carbon-containing fine-grained lead-zinc ore

Due to the characteristics of lead-zinc ore, flotation is often used as the main beneficiation method, including preferential flotation, partial flotation, equal flotation, branched series flotation and other methods. Through the ore sample test of the lead-zinc ore, it is learned that the ore contains a high carbon content and the carbon-zinc embedding relationship is complex. If the carbon is directly floated, some zinc will float out together. Therefore, it is decided to adopt the first carbon-zinc mixed flotation, and then the lead and zinc flotation method.

Carbon-zinc mixed flotation: Using CaO as a pulp pH adjuster, the lead-zinc grade and recovery rate increase with the increase in the dosage of CaO. For carbon-zinc mixed flotation, the natural pH value is better. Since the density of carbon is small, it can be floated by adding a small amount of kerosene. In order to determine whether the amount of kerosene can reduce the loss of lead minerals in carbon-zinc concentrate.

Water glass and sodium hexametaphosphate are used as dispersants to inhibit gangue. Relatively speaking, the effect of water glass is better than that of sodium hexametaphosphate. Appropriate addition of dispersant is beneficial to increase the lead content in carbon concentrate. A small amount of water glass is added to the rough carbon, preferably 500g/t.

Carbon-zinc flotation separation:The purpose of carbon-zinc-lead separation flotation is to reduce the lead content in carbon-zinc concentrate. The pH value suitable for flotation of lead minerals and sphalerite is different. At a higher pH value, sphalerite is conducive to flotation, while galena is effectively inhibited under the same conditions. Therefore, Na₂SO₃ is often used as a lead mineral inhibitor; SWS is used to inhibit lead, so that the lead in the carbon-zinc concentrate is as small as possible to ensure the quality of the carbon-zinc concentrate.

Lead-zinc flotation separation:ZnSO₄ is used as a inhibitor of sphalerite during lead-zinc separation and preferential flotation, Na₂SO₃ is used as an auxiliary inhibitor of ZnSO₄ when suppressing sphalerite, and ethylthiocyanate is used as a collector of lead minerals.

Lead-zinc separation regrinding:The purpose of regrinding is to further dissociate lead and zinc monomers to achieve better separation effect. As the grinding time increases, the zinc occupancy rate and grade in the lead concentrate decrease accordingly. Therefore, it is more appropriate to select a regrinding fineness of -38.5μm accounting for 85%.

Zinc flotation:CaO is used as a pulp pH adjuster for sphalerite flotation, with a dosage of about 2000g/t. CuSO₄ is an activator to activate the zinc that was suppressed in the previous step. The addition amount is determined to be 450g/t. The addition amount of the collector xanthate is 80g/t.

Finally, by adopting the carbon-zinc mixed flotation-lead and zinc separation flotation process, the carbon in the mineral is effectively removed, and good lead concentrate and zinc concentrate are obtained.

The above is an introduction to the flotation process of a carbon-containing fine-grained lead-zinc ore. In actual ore dressing plants, due to the different properties of lead-zinc ores, the selected flotation process methods are also different. It is recommended to conduct ore dressing test analysis, and design a suitable lead-zinc ore flotation process by analyzing the data, which has achieved an ideal return on investment.