On-line analysers are becoming increasingly important for real time process monitoring. A typical online analyser cannot handle the volumes of a primary slurry feed; thus a representative sample needs to be taken for accurate and precise reporting. Traditional mechanical samplers take a cross cut sample of the full stream at discrete intervals. To obtain real time information from an online analyser, a continuous sample needs to be taken.
Pierre Gy’s sampling theory (TOS) was extended to enable a true and representative sample to be extracted continuously.
Multotec’s Rotating Cone Sampler, as introduced at the WCSB 8 2017, provides a dry continuous discharge sample at division ratios up to 100:1 (or tailored for applications) that complies with TOS. Custom designed radially tapered cutters, coupled with linear cutter travel speeds of 0.2 m/s on the outer radius, across both stages of the sample extraction, pioneers representative sampling on continuous basis from vertical falling stream under gravity. Primary and secondary cutters are designed to rotate at irrational ratios to each other to prevent cyclic and short term periodic sampling errors. Perfect symmetry also sees adherence to correct sampling practices. The unit also allows for immediate rejects return to the main stream flow without additional rejects considerations.
A mechanically suitable distribution cone, manufactured to tolerance, from a range of materials of construction, stainless steel cutter blades (with optional replacement hoods) and robust pinion gear drive design with high torque factor cover most applications.
Schematic of flow through sampler showing the location of the distribution cone, radially tapered cutter, primary sampler, secondary sampler and rejects return.
- Intended applications and their physical limitations are tabled below.
- Material type = Dry flowing fine solids (grain, fertilisers, HM sands, iron ore fines, etc.)
- Maximum particle size 10 mm
- Angle of repose 25˚ – 40˚
- Moisture content < 3% – 4%
- Bulk density 720 kg/m3 – 2600 kg/m3
- Primary flow rate Up to 505 m3/h maximum
- Extraction ratio of primary flow ± 0.005
Sampler primary components in a cross section view
- Secondary electric drive
- Primary electric drive
- Tie beam
- Secondary cutter inspection and replacement hatch
- Primary cutter inspection and replacement hatch
Sampler assembly in isometric view