Small pilot scale coal preparation

Process overview

The small pilot-scale coal preparation plant does not wash all fractions concurrently. The coarse, fine and ultra-fine coal fractions are processed individually through stand-alone circuits. This has allowed ALS greater control of the sample processing stages. These stages are outlined below.

• De-sliming and Classification: de-sliming of the raw coal is performed by passing the coal through a linear vibrating screen (typically between 2.0 mm and 0.5 mm wedge-wire). This process separates the fine and ultra-fine particles from the coarse coal. The finer fraction, from the de-sliming process, is separated using a 600 mm circular vibratory screen (1200 mm & classifying cyclone in pilot plant) to produce fine (-1.4 mm +0.250 mm) and ultra-fine (<0.250 mm)
• Coarse Circuit: the coarse material is processed through three different units: 1) >19mm material beneficiated through the 1200mm dense medium drum on the pilot plant, 2) <19mm>9.5mm, is processed through a 600mm ID dense medium cone and the fine coarse product, and 3) the <9.5mm>1.4mm through a 250mm ID dense medium cone. The magnetite rinsing of these circuits is performed using the circular vibratory screen.
• Fines Circuit: the fines circuit (-1.4 + 0.250 mm fraction) in the mini plant is be processed through a set of spirals, with dewatering occurring via drainage beds.
• Ultra-Fines Circuit: the ultra-fine circuit plant utilizes a floatation column with a 150mm ID

Laboratory support

If there is limited coal washability information on the plant feed, ALS Coal is able to collect a sample to conduct a full washability analysis which can be used to identify the target densities to meet yield and target ash values. Each of the pilot plant products are typically dried, weighed and subsampled for ash percent. This provides guidance on the product ash and yield. A simulated overall plant product can be targeted by proportional blending of the product streams. Comprehensive coal characterization is provided on simulated product by sub-sampling the products and rejects and processing the coal through ALS' extensive laboratory network