Amid the global energy transition, nickel has become an indispensable “third metal” for electric vehicle (EV) power batteries. With the accelerating trend toward high-nickel chemistries, the demand for nickel resources continues to rise. Approximately 60% of global terrestrial nickel resources exist as laterite ores, and the high-pressure acid leaching (HPAL) process has emerged as the mainstream hydrometallurgical route for processing low-grade limonite-type laterite ores, offering nickel recovery rates of nearly 96% and cobalt recovery rates of 94%.

The intermediate product of HPAL—the mixed hydroxide precipitate (MHP)—is increasingly becoming the primary feedstock for battery-grade nickel sulfate due to its simple processing route and lower production costs. In the critical step of converting MHP to nickel sulfate—“acid dissolution → impurity removal → extraction”—the choice of extraction equipment directly determines nickel purity, recovery, and production costs.
To meet the unique requirements of the post-HPAL extraction process, Zhengzhou Tiei Extraction CWL-M series centrifugal extractor provides a highly efficient, continuous, and economical solution for deep nickel-cobalt separation.

Technical Challenges in Nickel Extraction from Acid-Dissolved MHP

After acid dissolution, MHP generates a complex liquid containing nickel, cobalt, magnesium, manganese, calcium, and other metal ions. Preparing battery-grade nickel sulfate requires nickel liquids with cobalt below 10 ppm and magnesium below 5 ppm, imposing extremely stringent demands on extraction and separation processes. Although conventional mixer-settlers are widely used, they have inherent limitations:

Multiple stages required: Nickel-cobalt separation typically requires 20–30 extraction stages, resulting in large footprints and high civil construction costs.
Low mass transfer efficiency: Relying on gravity mixing and settling leads to long residence times per stage, limiting throughput.
Emulsion and third-phase formation: Magnesium, aluminum, and other ions in MHP systems can induce emulsification, causing organic phase loss and unclear phase interfaces.
Severe solvent entrainment: Incomplete phase separation in mixer-settlers results in 5–10% organic phase entrainment, increasing reagent consumption and downstream processing burdens.

CWL-M Centrifugal Extractor: HPAL Extraction Units

Zhengzhou Tiei Extraction CWL-M series centrifugal extractor, based on enhanced separation via ultrahigh-gravity fields, offers a novel approach for efficient extraction and purification of acid-dissolved MHP liquids. The key technical advantages include:

1.Dramatically improved mass transfer efficiency, significantly reducing extraction stages
The CWL-M centrifugal extractor generates centrifugal forces of 800–1200G through high-speed rotation, instantly mixing the aqueous phase with extractants (such as P507 or Cyanex 272) at the micron scale. This increases the interfacial area 5–8 times compared to conventional mixer-settlers. Single-stage extraction efficiency can exceed 95%, and the number of stages required for the same separation is only 50–60% of that needed with traditional mixer-settlers. For nickel-cobalt separation, a conventional process requires 24 stages, whereas the CWL-M centrifugal extractor achieves the same with only 10–12 stages, reducing equipment count by more than half and saving 60–70% of floor space.

2.Rapid, clear phase separation, completely eliminating emulsification issues
Impurities such as magnesium and aluminum in acid-dissolved MHP liquids tend to form stable emulsions. The strong centrifugal force of the CWL-M centrifugal extractor separates the two phases within seconds, producing a clear, stable interface. Extractant entrainment is below 0.1%, significantly reducing organic phase loss and extending extractant regeneration cycles.

3.Fully sealed, corrosion-resistant design for harsh operating conditions
All wetted components are made of high-quality stainless steel or duplex steel, resistant to sulfuric acid and chloride corrosion. The fully sealed structure prevents organic solvent volatilization, improves working conditions, and meets the EHS requirements of modern chemical plants.

4.Precise process control to ensure product purity
Equipped with a PLC-based automatic control system, the CWL-M centrifugal extractor allows precise adjustment of rotation speed, flow ratios, and other parameters. Combined with multistage countercurrent extraction, it enables deep separation of nickel from cobalt and magnesium. In practice, using three-stage countercurrent extraction with P507 reduces cobalt in nickel liquids from 2–3% to below 10 ppm. Subsequent two-stage extraction with Cyanex 272 lowers magnesium content to below 5 ppm, fully meeting battery-grade nickel sulfate quality standards.

Practical Applications: Full-Process Support from Laboratory to Industrial Scale

Zhengzhou Tiei Extraction has provided centrifugal extraction equipment and process services for multiple HPAL nickel laterite projects targeting MHP nickel recovery. In one HPAL project, replacing conventional mixer-settlers with CWL-M series centrifugal extractors yielded remarkable results:

Extraction stages reduced from 22 to 10, cutting floor space by 65%.
Nickel recovery increased from 94.5% to 98.2%.
Extractant consumption reduced by 35%, saving over 2 million RMB annually.
Produced nickel sulfate meets battery-grade standards (Ni ≥ 22%, Co ≤ 8 ppm, Mg ≤ 3 ppm).

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Email: sales@tieiextraction.com
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