How can the Phosphoric Acid Production be Monitored?

Relevant for phosphoric acid production, hydrogen halide production, fuel cells, etching

Phosphoric Acid Production

For industrial production of phosphoric acid (H3PO4), the mineral apatite and sulfuric acid (H2SO4) are used. At first the ore-bearing mineral is concentrated by flotation. Then the apatite is forwarded to a reactor to which sulfuric acid is added. In the reactor the two ingredients react to form phosphoric acid and calcium sulfate. H3PO4 is widely used, e.g. for hydrogen halide production, as a food additive (E338), as electrolyte in phosphoric acid fuel cells, for copper-electropolishing and as an etching agent for semiconductors.

Inline Density Sensor L-Dens 7400 Version Tantalum

The acid monitor from Anton Paar, equipped with the inline density sensor L-Dens 7400 Tantalum and a Pico 3000 Process Instrumentation Controller, continuously monitors and displays the concentration of sulfuric acid and phosphoric acid. The use of Tantalum for all wetted parts ensures complete resistance against the used acids also at higher temperatures. Phosphoric acid is measured in the concentration range from 0 % to 100 % at temperatures between 0 and 60°C. The acid monitor achieves a measuring accuracy of ± 0.05 % for the measurement of H3PO4 as well as H2SO4, depending on temperature range, measuring range and contamination.

Depending on the concentration range, the sulfuric acid concentration can also be measured with the L-Sonic 5100 Version ROC which is plated with chemically resistant gold material and can be directly integrated in the process. This ensures a long and maintenance-free life cycle.


  • 24-hour monitoring of acid concentration
  • Reduction of sulfuric acid and apatite consumption
  • Increased process and product quality
  • Highly accurate measurement results

Learn more about the L-Dens 7400


Specifications  L-Dens 7400 Version Tantalum

Measuring range: max. 3000 kg/m3
Process temp. range: -25 to +125 °C
Ambient temp. range: -40 to +65 °C
Pressure range: max. 50 bar
Typical repeatability: ±0.02 kg/m3

Other relevant instruments

Process Instruments:

Laboratory Instruments: