Following extensive R&D into an innovative new approach to dry belt sampling, the first Multotec True-Belt sampler has been ordered by a customer in the gold mining industry. This order followed shortly after the patented True-Belt sampling technology was showcased at an international sampling conference held in Perth, Australia, in August 2012. The sampler’s design is based on existing go-belt technology but incorporates several design features which guarantee the structural absence and near elimination of sample bias.

In the improved cross belt design, the material is sampled only after it has been removed from the belt in a manner that gives every fragment on the belt the same probability of ultimate selection into the sample. “Cross-belt cutters are widely used for taking samples, particularly in the coal industry,” Rolf Steinhaus, Director at Multotec Process Equipment, says. “However, few sampling experts believe that the samples taken using cross-belt cutters can be regarded as unbiased. “The True-Belt sampler takes samples from the flow on a conveyor belt, avoiding the typical sources of bias. Material is thrown off a belt by a rotating plough and a sample is taken from the thrown material using fixed cutter blades. The sample is taken from somewhere near the middle of the material thrown off, so that particles which might have been affected by the ends of the plough are not included in the final sample.”

In this way, a series of fixed cutters adjacent to each other allow for replicate or dual samples and reject material is collected in the regions of thrown material from plough extremities, via separate chutework. Multotec approached the Commonwealth Scientific and Industrial Research Organisation(CSIRO), Australia’s national science agency, in 2010 to carry out discrete element modelling (DEM) analysis to refine its conceptual prototype and seven experiments were conducted using DEM.