Process for the Simultaneous Recovery of Sulphur and Iron from Pyrite

During the beneficiation of pyrite, recovery rates often fall short of expectations; the primary reason for this is usually a failure to tailor the separation process to the specific mineral composition of the ore. There are significant variations across different mining areas in the associated impurities, clay content and the occurrence of valuable metals in pyrite; simply applying a generic process is highly likely to result in substantial losses of sulphur and iron resources.

I. Analysis of Ore Mineral Characteristics

The primary valuable mineral in the target ore is pyrite, accompanied by small amounts of sulphates and free sulphur; the ore also has a relatively high clay content. Clay-rich material significantly impedes the effectiveness of flotation reagents and deteriorates the slurry separation environment. Unless each process stage is specifically optimised, it is difficult to achieve production standards for the two core indicators—sulphur concentrate recovery rate and grade—resulting in a significant reduction in resource utilisation efficiency.

II. Crushing Process: Three-stage, closed-circuit crushing with strict control of final particle size

Crushing is a fundamental process at the front end of mineral processing. This mine employs a proven three-stage, closed-circuit crushing process. Through a combination of multi-stage crushing and screening in a closed-circuit operation, the final particle size of the crushed material is strictly controlled to not exceed 12 millimetres. A uniform and stable feed particle size reduces the load on downstream grinding equipment and avoids two common issues: insufficient liberation due to excessively coarse particles and excessive slime formation due to excessively fine particles, thereby laying a solid foundation for the grinding and flotation separation processes.

III. Grinding and Flotation Separation System: Two-stage Grinding Combined with a Standardised Flotation Process

The crushed ore enters a two-stage closed-circuit grinding system, achieving thorough individual liberation of pyrite from gangue minerals at each stage. Following grinding, a standard flotation process comprising one roughing stage, one scavenging stage and two concentrating stages is employed, prioritising the enrichment and recovery of sulphur concentrate. The staged flotation process progressively removes impurities such as silicates and clays, effectively enhancing the purity of the sulphur concentrate and minimising the loss of valuable sulphide minerals in the tailings.

IV. Magnetic Separation for Iron Recovery: In-depth Recovery of Iron Concentrate from Flotation Tailings

The tailings discharged from flotation still contain recoverable iron-bearing minerals. To fully realise the comprehensive value of the ore, a strong magnetic separation recovery process is employed. The overall process adopts a combined route of strong magnetic roughing — regrinding for liberation — secondary strong magnetic cleaning, subjecting the flotation tailings to in-depth re-sorting to separate and produce qualified iron concentrate. This enables the simultaneous recovery of both sulphur and iron resources, significantly enhancing the mine’s overall economic benefits.

V. Concentrate Dewatering and Water Recycling Environmental Protection Process

The sulphur concentrate and iron concentrate obtained from the separation process are uniformly subjected to a two-stage dewatering treatment comprising thickening and filtration. The moisture content of the finished concentrates is strictly controlled to remain stable within the range of 15%–18%, meeting storage and transport standards. All mineral processing wastewater generated during production is collected and recycled, reducing the consumption of fresh water resources and achieving clean, green production.

Support and Assurance through Professional Mineral Processing Trials

To stabilise all key indicators in pyrite-sulphide ore beneficiation, preliminary mineral processing trials are essential. Our specialised pilot plant for comprehensive mineral utilisation can conduct full-process beneficiation trials on various types of ore. Having accumulated practical experience in the beneficiation of over 70 types of minerals, we customise complete process solutions based on trial data, thereby avoiding process design flaws at source and reducing investment losses in mining projects.