Home Product Knowledge Lead-Zinc Oxide Ore Beneficiation Technology: Challenges and Process Breakthroughs

Lead-Zinc Oxide Ore Beneficiation Technology: Challenges and Process Breakthroughs

2025-10-01 Xinhai (9)

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Oxidised lead-zinc ores constitute over 35% of global reserves, representing a vital successor resource. However, their beneficiation remains an industry-wide challenge, characterised by low recovery rates, high reagent consumption, and complex processing flows. Achieving economically efficient recovery of oxidised ores is crucial for enhancing resource utilisation. This paper delves into the technical difficulties and systematically introduces modern beneficiation solutions centred on ‘activation-collecting’ principles.

I. Ore Properties: Complexity and Technical Challenges

Lead-zinc oxides primarily occur as galena (PbCO) and smithsonite (ZnCO), exhibiting properties markedly distinct from sulphide ores:

Strongly hydrophilic surfaces: Mineral surfaces are rich in hydroxyl and carbonate groups, readily forming robust hydration layers that severely impede collector adsorption.

Complex Ore Composition: Frequently intergrown with silicate and carbonate gangue minerals, exhibiting severe muddiness that disrupts separation processes.

Poor Natural Floatability: Inherently difficult to float, necessitating artificial activation and modification for effective flotation.

These characteristics are the fundamental causes of low recovery rates and high processing costs.

II. Flotation Principles and Reagent Regimes: Artificial Activation

Flotation of oxide ores adheres to the principle of ‘artificially enhancing floatability,’ centred on creating a floatable surface through reagent activation.

Sulphide Activation: Sodium sulphide (NaS) is initially added to react with the mineral surface, forming an artificial sulphide film.

Specific Collecting: Activated minerals are then recovered using collectors that exhibit specific affinity. Commonly employed include:

Fatty acids (e.g., oleic acid): Possess strong collecting capacity but are sensitive to pulp temperature and hardness.

Aminic collectors (e.g., dodecylamine): Operate via electrostatic adsorption under strongly alkaline conditions (pH 11-13).

This reagent system requires precise control of sodium sulphide dosage (excess inhibits flotation), alongside inhibitors like water glass and pH adjusters such as sodium carbonate, making management more complex and costs significantly higher than for sulphide ores.

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III. Process Flow and Core Equipment: Refinement and Integration

To overcome inherent technical limitations of the ore, oxide ore beneficiation necessitates more refined and integrated process flows.

Critical Pre-treatment – Desliming: Equipment such as spiral classifiers and hydrocyclones must be employed for preliminary desliming to remove fines below -10μm. This substantially reduces unnecessary reagent consumption and minimises interference with the flotation environment.

Core Process – Activation-Flotation: A typical sequence comprises ‘desliming – sulphide activation – roughing – multi-stage scavenging’. The flotation cycle is relatively lengthy, necessitating precise control of parameters at each stage. 

Integrated Process Application: For refractory ores, a combined ‘gravity separation-flotation’ process is often employed. Coarse-grained oxidised ore that has been liberated into individual particles is first recovered using gravity separation equipment such as shaking tables. The resulting fine-grained tailings are then fed into the flotation system, creating complementary advantages to maximise recovery rates.

Core Equipment Selection:

Pre-sulphidation agitation commonly employs JJF flotation machines to ensure thorough reagent-slurry mixing. 

Flotation operations may utilise BF-type or other aerated flotation machines to enhance recovery of fine minerals. 

Additionally, comprehensive classification, desliming, and gravity separation equipment (e.g., vibrating screens, hydrocyclones, shaking tables) must be integrated.

Conclusion

The beneficiation of oxidised lead-zinc ores constitutes a technology-intensive endeavor, centred on overcoming inherent ore deficiencies through ‘desliming pre-treatment’ and ‘sulphide activation’. Despite complex processes and elevated costs, economically viable recovery remains achievable through refined reagent regimes and integrated processing flows. This holds profound strategic significance for mobilising vast oxidised ore reserves and safeguarding the security of the lead-zinc supply chain.



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