Fines Processing

Classifying

The size based classification of fine particulate material can impact the efficiency of a number of downstream processes. The accurate tracking of performance, identification of key performance indicators, adjustment of set points and sizing of equipment components all contribute to ensuring the efficiency of the classification process.
In plants which do not beneficiate ultra-fines, the performance of a classifying cyclone cluster directly impacts on plant yield. For example, in a 1000 t/h washplant with 20% of the feed reporting to the desliming screen underflow, 5% of material misplaced to the cyclone overflow can be 10 t/h. This material then directly reports to tailings. At an assumed fines yield of 60% and a sale price of $100/t, this translates to a nominal revenue loss of $4.26 million per year for a 7100 h/annum CPP.

Fines Beneficiation

Fines beneficiation processes are relatively minor components of CPPs compared with dense medium processes; however the inherently lower separation efficiencies and improved liberation of the fines fraction mean that significant variation of revenue results from inconsistencies in the operation of this equipment. The performance of equipment such as spirals, Reflux Classifiers (RC) and Teetered Bed Separators (TBS) can be tracked by sampling and analysis of feed and product streams, in the same manner as dense medium cyclones or baths. This data can be analysed and used to identify and assess the impact of problems as they occur.

Assessing the impact of yield losses on a 1000 t/h plant (with 10% reporting to the fines beneficiation circuit) shows that 5% misplaced material to reject gives a 5 t/h loss of product and a subsequent $3.55 million revenue loss per year for a 7100 h/annum CPP assuming a coal price of $100/tonne.

QPS Consulting Services

QPS consultants have experience in the operation, optimisation and troubleshooting of cyclones, spirals and teetered bed separators. Through site visits and data review, QPS can suggest any required equipment replacements, changes in operational settings or circuit modifications to improve the operation of a fines processing circuit.