DE-SLIMING OF PENALTY U-BEARING PARTICLES IN THE RECLEANER FEED OF A COPPER CONCENTRATOR

Jim Pae Lem1, William Skinner2, Massimiano Zanin2

1Department of Mining Engineering, Papua New Guinea University of Technology, PMBS, LAE 411, Papua New Guinea

2Ian Wark Research Institute, University of South Australia, Mawson Lakes Campus, Mawson Lakes, SA 5095, Australia

ABSTRACT

It is well known that the specific density of minerals has adverse influence on the classification performance of a hydrocyclone, particularly when liberated high density minerals such as gold or uranium are present in sulphide ores. These liberated heavy minerals often misreport to the underflow and recirculate to the system. Such phenomena do result in serious issues in closed-grinding circuits, such as overgrinding, leading to production of flaky particles (as in gold) or ultrafines. In plants which present gold liberated at coarser size, loss of gold due to overgrinding is sometimes prevented by incorporating gravity concentrators into the grinding circuit to recover the gold. The work reported in this paper looks at whether density effect will affect successful rejection of liberated U-bearing particles in the -10 μm size range of a plant recleaner feed, which is a strategy to minimise penalty U accumulation in a copper concentrator. The study was carried out using a cyclone rig with spigot diameter of 0.25 inches. It was found that density effect is almost negligible at particle sizes below 10 μm. Consequently, the liberated U-bearing particles finer than 10 μm were successfully removed in the overflow stream as rejects and hence U grade in the copper flotation concentrate remarkably reduced, by 19 ppm. Based on the results, de-sliming of the recleaner feed was recommended for plant trial and implementation.

Figure 1 Particle size distribution of the cyclone rig cut overflow, d90 = 6 µm as defined by Malvern Mastersizer 2000

Figure 2 Flotation recoveries by size of (a) copper and (b) uranium indicating the decrease in U recovery as a result of de-sliming

KEYWORDS

Specific gravity of minerals, classification, uranium, flotation