DETERMINATION OF THE GRINDABILITY OF DARANNA-KA´OJE MANGANESE ORE, KEBBI STATE, NIGERIA
Publication Date : 22/05/2020
The determination of the Daranna-Ka´oje manganese ore commenced with the systematic grab sampling of bulk material from 3 stationary stockpiles each of crushed run-of-mine (r-o-m) ore comprising of – 80 mm + 10 mm coarse and – 10 mm fine particles with a shovel at every 10 feet walk around their base. Later, the head sample of both reference (Itakpe iron ore) and test (Daranna-Ka´oje manganese ore) samples were generated by reducing their individual bulk samples to -5 mm + 2 mm size range particles with hammer mill and re-blended. Then 300 g each of the reference ore and the test ore were exposed to sieving through a nest of nine sieves comprising of 2000 µm, 1400 µm, 1000 µm, 710 µm, 500 µm, 355 µm, 250 µm, and 180 µm selected based on square root of two (√2). This was followed by grinding under the same parameters of mill size, grinding media, mill charge and tumbling time at 1425 rpm and final sieving. Using Gaudin Schuhmann relation for the determination of 80% feed and products of the reference and test ores; the grindability was determined from the generated results of the pulverised and ground sieve analyses by correlating the two ores’ work index. The ascertained grindability of 31.94 kWh/t implies that the grinding energy required per unit mass of the Daranna-Ka´oje manganese ore is more than twice the 15.86 kWh/t grinding energy required per the same unit mass of Itakpe iron ore under the same parameters. This is not out of place as the Daranna-Ka´oje manganese ore head sample is mostly made up of spessartine; which has hardness of 7 to 7.5. Moreover, manganese though similar with iron in some properties is harder as an element. Therefore, it is recommended that the design of comminution circuit should have more stages than that of Itakpe iron ore.
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