ANALYSIS OF ELECTROSTATIC SEPARATION FOR RUTILE CLEANING DUTY USING A PLATE ELECTRODE ASSISTED HIGH TENSION ROLL SEPARATOR

摘要

A plate assisted electrostatic high tension roll separator has been used for the removal of impuritymineral grains from a rutile rich product stream. A laboratory study and a subsequent productionstudy explored the effect of machine conditions with a view to the optimisation of the separationperformance of the separator. The performance requirement was that the TiO_2 grade in the nonconductorstream was to be less than ten per cent whilst at the same time the ZrO_2 grade in theconductor stream had to be less than 0.5 per cent at mass recoveries of greater than 90 per cent tothe conductor stream and less than 5 per cent to the non-conductor stream. Mineralogy data wasutilized to determine the feasibility of achieving the production targets with the feed under study.Since the feed stream mineralogy was dominated by rutile, leucoxene and zircon, it was possible touse an approximation to the actual mineral assemblage as well as the raw X-ray fluorescence data tounderstand the separation duty of the Carrara machine.Since there were four conflicting criteria used for the performance requirement, an index wasdevised that incorporated all the requirements simultaneously. This new index was the sum of thesquares of the difference between the achieved and desired values, weighted with respect to thevariance of each variable. If the desired value for a particular criterion had been met its contributionto the sum was set to zero, no matter how well the criterion had been met.For the production machine the strict requirements were almost achieved. As expected, theachievement of the target performance was dependent of the feed conditions at the time ofmeasurement. This paper reports the results of this study.