A robust industrial solution that integrates a laser diffraction particle sizing sensor with a fully automated two-stage sampling and concentration control unit to deliver continuous on-line slurry measurement. Used to monitor, control and optimize the performance of thickeners, grinding circuits and froth flotation units, and for QC, the PSI 500 requires no calibration and meets the specific requirements of the minerals and mining sectors, offering:

  • Measurement at three different sampling points using a single unit for maximum system productivity.
  • Fully integrated, automated sample preparation for dependable analysis with minimal manual input.
  • Easy-to-use software and fully automated operation to minimize training requirements and release operator time.
  • Integration with existing control platforms to simplify development of automated control protocols.
  • High reliability of >95% with little downtime, minimal maintenance and maximum ROI.
  • Automatic line flushing and cleaning to ensure high system availability.

The PSI 500 integrates sample dilution hardware with a robust laser diffraction particle sizing sensor. Both elements of the system are tailored to meet the requirements of minerals and mining industry for fully automated, on-line solutions for continuous monitoring and multivariate control.

For accurate laser diffraction analysis light must be able to penetrate through the sample, a limitation that imposes an absolute upper concentration limit for measurement. Multiple scattering, where the laser light interacts with more than one particle prior to detection can also be an issue. Sample dilution is therefore an essential element of analysis for more concentrated streams.

Sample dilution
In this system a primary splitter extracts a flow rate of between 50 and 170 l/min from the bulk process flow. A secondary sampling system then extracts a 0.01 to 0.03 representative slice of this primary flow every 10 to 30 seconds by moving the sample line across a stationary cutter. A second cutter provides calibration samples and undiluted material for off-line analysis. The frequency of the secondary sampling process is controlled to give acceptable concentration in the measurement zone, following dilution, with most of the primary flow rejected and recycled to the process.

A diluter unit mixes water with the secondary sample to meet the concentration requirements of the laser diffraction sensor. The dilution ratio is typically in the order 10 to 100 and the residence time in the tank is usually around 1 minute. The dilute sample flows directly to the optical sensor, turbulent flow ensuring that the full particle size distribution of the sample is accurately measured.

Sample Measurement
All Insitec systems use the technique of laser diffraction to rapidly measure particle size, employing patented multiple scattering algorithms to extend the working concentration range of the technique. These algorithms mathematically correct for the concentration-dependent effect of multiple scattering reducing sample dilution requirements to a minimum and ensuring that all measurements are robustly independent of sample concentration.

In this fully automated solution complete particle size distributions are measured at a rate of one per minute. These data provide a secure foundation for better process control whether that control is manual or automated.

Data presentation and use
Insitec systems are integrated within the process plant. Typically they are operated from a centralized control room and the measurement results drive routine decision making. Powerful software packages make integration and data interpretation straightforward.

Malvern Link II software provides the functionality required to integrate an Insitec within the existing control system and to automate process control. It allows operation of the analyzer from either a dedicated PC or from existing control mimics. Importantly Malvern Link II is not confined only to Insitec integration. This software also eases integration with other instrument types, simplifying multivariate control.

RTSizer software presents the measurement data in a clear and accessible way. Results reporting can be tailored to industry and customer norms to improve information flow. Insitec data are used to:

  • Improve process understanding.
  • Deliver instant upset detection.
  • Support comprehensive process optimization.
  • Automate process control.

Because complete particle size distributions are reported, monitoring and control can be based on whichever size fraction is of interest; the fines, the 3 to 30 micron fraction, the amount of material over 200 microns, for example. Insitec data drive optimized manual control strategies and enable the full automation of process control, delivering substantial economic returns.


Measurement type:
Particle size
Measurement range:
0.1 to 2500µm
Measurement principle:
Laser diffraction
Optical models:
Mie theory
±2% on Dv(50) reported using the verification reticle


Enclosure rating:
Operating platforms:
10 bar (g)
RTSizer (for instrument control) Malvern Link II (for system automation and data link)
Maximum distance from instrument to PC:
500m (up to 2 km using fiber optics)

Operating environment

10°C – 70°C
35% - 80% (non-condensing)