Chatham Rock Phosphate Ltd.’s initial testing of sensor-based ore sorting of Korella phosphate has shown particularly positive results.
Chatham engaged Tomra Sorting to establish if its sensor-based sorting systems were capable of sorting Korella phosphate ore from waste material to improve the already relatively high-grade direct shipping ore.
The testwork demonstrated that Korella phosphate could be upgraded from a nominal feed of 30 per cent P2O5 to a product in the range of 35 per cent to 38 per cent P2O5 at acceptable recovery rates.
Korella’s low-cadmium phosphate in the range of 35 per cent to 38 per cent P2O5 is higher grade than most internationally traded rock phosphate and is particularly suitable for use by European fertilizer producers which previously depended on Russian apatite for supplies of high-quality phosphate.
The testing process
Sortability testing is an idealized multistage sorting program designed to produce a sortability curve, which can be used to determine sorting cut points to be rigorously tested at appropriate throughput rates in further bulk-scale performance testwork.
The purpose of the set of testwork was to determine the suitability of a Tomra sorting system to Korella operations.
In this instance, Tomra’s XRT (X-ray transmission) sorter was used.
Tomra’s engineers conducted sortability testwork from an approximately 740-kilogram sample of simulated run-of-mine Korella phosphate. Bulk material was prescreened to eight to 25 millimetres and 25 to 75 millimetres for testing.
The results from this set of testwork were excellent for both size fractions.
Significant waste mass reductions were achieved in all runs while achieving excellent recoveries in initial runs and higher-grade product options in subsequent runs.
Excellent waste removal potential was demonstrated in several steps with various P2O5 grade/recovery options available based on amount of waste removal desired.
Future testing
Using the sortability curves determined from the testing, future bulk performance testing will be implemented.
The future testing will be at the desired cut point to demonstrate sorting performance at the required throughput rate using a larger sample.
The larger, more representative sample of at least 500 kilograms of material per run will be in the recommended size range of eight mm to 75 mm.
A total sample of approximately 2,000 kg will be required, and will be recovered from trenching and/or large-diameter drilling from a Korella deposit, and this next round of testing will also be conducted on a full-scale sorter.
Over all, the results from the Korella material show a positive amenability to Tomra’s XRT sorting technology.
This presents an exciting opportunity for a productive partnership between Tomra and Chatham Rock, leading to developing and optimizing an industry-leading sorting solution for Chatham Rock at Korella.
