For rock phosphate beneficiation, the most commonly used anionic flocculants are high-molecular-weight anionic polyacrylamide (APAM) and modified anionic polymers designed for tailings settling, thickening, and slurry clarification. These flocculants help improve solid–liquid separation, concentrate recovery, and water recycling in phosphate processing plants. Below is a detailed explanation of the suitable types and specifications.

1. Most suitable type: High-molecular-weight Anionic Polyacrylamide (APAM)

In phosphate beneficiation plants, polymer flocculants are widely used in thickener, tailings dam, filtration, and wastewater treatment. Among them, anionic PAM is usually preferred because phosphate ore slurry contains negatively charged clay, silica, and carbonate particles.

• Polyacrylamide is widely used in mineral processing wastewater and tailings flocculation, including phosphate ore beneficiation.

• Studies on phosphate tailings show that anionic polyacrylamide gives high settling rate, high water recovery, and low turbidity, making it one of the best choices.

Recommended specification

High molecular weight helps polymer bridging → larger flocs → faster settling.

2. Medium-charge anionic PAM for phosphate slurry thickening

Rock phosphate beneficiation slurry usually contains:

• Clay minerals

• Silica

• Carbonates

• Fine apatite particles

These particles require medium charge anionic flocculant for good adsorption and bridging.

Functions:

• Increase sedimentation speed

• Improve thickener overflow clarity

• Reduce filter cake moisture

• Improve tailings disposal

Polymeric flocculants promote aggregation of fine particles and improve filtration and dewatering efficiency in mineral processing.

Recommended type:

• Medium anionic charge (20–30%)

• Very high molecular weight

• Fast dissolution

3. Very high molecular weight APAM for tailings dam / water recovery

In phosphate beneficiation plants, large amount of fine tailings must be treated.

Use:

• High MW APAM (18–25 million)

• Low to medium charge

Advantages:

• Fast settling in thickener

• High solid content underflow

• Clear recycle water

• Lower flocculant consumption

Research on phosphate tailings shows polymer flocculants like PAM and PEO significantly improve settling rate and solid concentration.

4. Selective flocculation in phosphate beneficiation

In some phosphate plants, flocculant is used for selective flocculation to separate:

• Apatite

• Quartz

• Clay

Hydrolyzed polyacrylamide and polyacrylic polymers have been used for selective flocculation in phosphate beneficiation processes.

Recommended type:

• Low charge anionic PAM

• Controlled dosage

• High molecular weight

Used in:

• Desliming

• Fine particle recovery

• Selective separation

5. Typical anionic flocculant models used in phosphate beneficiation

Common industrial grades include:

• APAM A1215 / A1220 / A1230

• Magnafloc 10 / 1011 / 155

• Zetag anionic series

• Praestol A series

• Flopam AN series

Typical selection:

6. How to choose the correct anionic flocculant

Selection depends on:

• Ore type (sedimentary / igneous)

• Clay content

• Particle size

• pH

• Solid concentration

• Thickener design

Key rule:

Jar test is always required before final selection.

7. Conclusion

For rock phosphate beneficiation, the best anionic flocculant is:

✅ High molecular weight anionic polyacrylamide
✅ Low to medium charge density
✅ Fast dissolving powder or emulsion
✅ Designed for mineral processing

These flocculants are mainly used in:

• Thickening

• Tailings settling

• Filtration

• Wastewater treatment

• Selective flocculation

They improve:

• Recovery rate

• Water recycling

• Slurry settling speed

• Plant efficiency