Centrifugal extractor is a key equipment to realize solvent extraction operation. In hydrometallurgy, especially for the treatment of low-grade nickel ore (such as the leachate after high-pressure acid leaching/normal-pressure acid leaching of laterite nickel ore), solvent extraction is an efficient technology for separating, purifying and enriching nickel. Its basic principle is to selectively transfer nickel ions by using the difference in solubility of nickel ions in two immiscible liquids (usually aqueous leachate and organic extractant).
Process Requirements
- Raw material liquid characteristics
Low nickel concentration: The nickel content in the leaching solution is usually 1~5g/L, and efficient enrichment is required.
High impurity load: Contains a large amount of Fe³⁺, Al³⁺, Mg²⁺, Mn²⁺ ions (the concentration is often more than 10 times higher than nickel).
Strong acid environment: Sulfuric acid leaching solution with pH=1.5~2.5 requires corrosion-resistant equipment.
Micro suspended matter: The solid content needs to be controlled to <0.1% (to avoid clogging the flow channel). - Extraction agent selection
Prioritized nickel selectivity: LIX 84-I (oxime) or Cyanex 272 (phosphorus) are commonly used, and nickel and cobalt are efficiently extracted at pH=3.5~5.5.
Diluent: sulfonated kerosene (to ensure the stability of the organic phase). - Process objectives
Nickel recovery rate>98%, enrichment concentration>40g/L (to meet the requirements of electrowinning).
Nickel/impurity separation coefficient>1000 (such as Ni/Fe, Ni/Mg).
Solvent recycling rate>99.5% (to reduce losses).
Extracting Nickel From Low-grade Nickel Ore Process
- Pretreatment
The leaching solution is finely filtered (to remove particles > 5 μm) and the pH is adjusted to 3.5~4.5 (neutralized with lime milk). - Multi-stage countercurrent extraction
Equipment: Zhengzhou Tiei CWL-M series centrifugal extractor (3~6 stages in series).
Operation:
The leachate (aqueous phase) is contacted in countercurrent with the organic phase containing the extractant.
Rapid mixing and separation (<60 seconds) under centrifugal force (>500g).
Nickel is transferred to the organic phase, and impurities remain in the aqueous phase (raffinate discharge). - Washing
The organic phase loaded with nickel is washed with a dilute acid solution to remove impurities (such as Mg and Ca). - Stripping
The organic phase is stripped with 2~3M sulfuric acid, and the nickel is transferred to the aqueous phase to obtain a high-purity nickel solution (>40 g/L). - Regeneration of the organic phase
The organic phase after stripping is regenerated by alkali washing and circulated back to the extraction section.
Advantages of Centrifugal Extractor
- High-efficiency separation capability
Centrifugal force drives the two-phase contact time to less than 30 seconds, avoiding emulsification, and the nickel single-stage extraction rate is greater than 95%.
Stage efficiency is greater than 95% (traditional mixer settler is only 80~90%). - Adaptability to extreme working conditions
Strong acid resistant (pH 1~14), material optional Hastelloy/PP lining.
Tolerates trace suspended solids (<0.1%), reducing pretreatment costs. - Energy saving and economy
Power consumption is reduced by 50%: the power of a single machine with a processing capacity of 10m³/h is ≤7.5kW.
Solvent retention is reduced by 70%: the liquid holding capacity of the equipment is only 0.1m³ (the same level mixer settler requires 1m³).
The floor space is reduced by 80% (modular series design). - Automation and stability
Integrated PLC control, real-time monitoring of ratio (O/A), flow rate, and pH.
The sealing design ensures that the solvent evaporation loss is less than 0.001%/h (VOC emissions meet the standards).
Through Zhengzhou Tiei centrifugal extractor, high efficient, low-cost green extraction of low-grade nickel ore can be achieved, significantly improving the economic benefits of hydrometallurgy.
Email: sales@tieiextraction.com
Whatsapp: +86 19069612820
