P₂O₅

≥ 30% (Premium: ≥ 32% - 36%)

The primary value driver. Higher content means lower ore and acid consumption per ton of phosphoric acid or fertilizer produced.

MgO

≤ 1.0% (Premium: ≤ 0.5%)

The most critical harmful impurity. Increases viscosity of phosphoric acid, creates unfilterable sludges, and severely disrupts plant operation.

Fe₂O₃ + Al₂O₃ (R₂O₃)

≤ 2.5% - 3.0%

Form colloidal precipitates that clog filters, increase P₂O₅ losses, and affect the color of the final product.

CaO

~ 45% - 52%

A primary constituent. The CaO/P₂O₅ mass ratio (ideal ~1.4-1.6) is key for predicting acid consumption.

SiO₂

Varies by deposit (e.g., 5% - 15%)

Inert gangue; provides a "skeleton" in the reaction slurry, but excess amounts add unnecessary load.

CO₂

≤ 3.0% - 4.0%

Indicates carbonate minerals (e.g., dolomite), which are associated with harmful MgO.

Cd (Cadmium)

≤ 20 mg/kg P₂O₅ (stricter in EU)

Critical environmental/safety指标. Heavy metals can enter the food chain through fertilizers.

Cl (Chloride)

≤ 0.1%

Highly corrosive to stainless steel equipment; must be strictly controlled.

Particle Size

For wet-process acid: -100 mesh (-0.15mm) or -200 mesh (-0.074mm) ≥ 80%.

Moisture

≤ 10.0% (Typically controlled at 8%-10% for handling and transport).

Appearance

Fine powder or granules, uniform color.