SEPARATION TECHNOLOGIES volume of ore using smaller cyclones, Khonbond would have needed to install nine hydrocyclones of the 400 size( eight active plus one standby). To reduce the number of hyd rocyclones in a cluster, the Weir specialists recommended upgrading the first-generation CVX units to the new CAVEX ® 2 CVD hydrocyclones. They determined that the CVD cyclones would process 25 % more volume than the CVX ones. Three 400CVD cyclones plus one of standby would handle the same or bigger volume of ore as eight 400CVX units plus one on standby. Based on the Weir team’ s calculations and test work, they advised Tata Steel to retrofit six CAVEX ® 2 400CVD hydrocyclones into the existing cluster at the Khondbond site in order to meet their target iron yield. This solution also meant that the footprint didn’ t need to be expanded.
After a simulation study and sampling, a 145mm vortex finder and 70mm spigot for the 400CVD hydrocyclones were selected for the test trial. With this configuration, three different operating pressures – 1.6 kg / cm 2, 1.8kg / cm 2 and 2.0kg / cm 2 – were trialled. For each operating condition, samples of hydrocyclone feed, overflow and underflow were obtained.
The samples were analysed for solids concentration and particle size distribution( PSD). Mass flow of solids and water in the feed was back calculated from the measured mass of overflow and underflow samples. Mineralogical composition of feed, overflow and underflow samples were characterised using XRD to quantify the percentage of alumina oxide in the various st treams.
The results demonstrated that the hydrocyclone overflow P80 decreased and the percentage of alumina oxide was elevated when the feed pressure was increased. In other words, the CAVEX ® 2 hydrocyclone produces a finer cut size and reduces the percentage of alumina oxide in the iron concentrate.
At the conclusion of the trial, the desliming circuit with the CAVEX ® 2 hydrocyclones had an improved plant yield of 8.1 %, achieving the target set by Tata Steel. This 3 percentage point increase in iron ore recovery meant that Tata Steel were able to increase their production by 0.18mtpa, generating an additional US $ 3 million per annum.
In summary, when compared with the CAVEX
X ®
650CVX hydrocyclone, the new CAVEX ® 2 400CVD improved three aspects of classification. Firstly, it produced a finer cut in the overflow and, secondly, it maximised the yield percentage, which, in turn, improved the percentage of iron in the concentrate.
Switzer:“ So, are these results replicable and scalable? In a changing iron ore market, these performance improvements provide operators with a significant gain in the recovery of iron value, which improves the techno-commercial feasibility of the steel making process and reduces the amount of iron lost in the tailings.”
She adds:“ In many ways, the trial demonstrated – once again – what Weir already knew. Namely, that its CAVEX ® 2 hydrocyclone, which features an innovative LIG + ™ laminar spiral inlet design, improves the separation efficiency and lowers the misplacement of fines in underflow. Moreover, the results illustrate that the combination of the new inlet and chamber design in the CVD hydrocyclone reduces flow turbulence and promotes an increased volumetric capacity of approximately 30 %. Therefore, the use of the CVD hydrocyclone can help operators to achieve more throughput, improve plant recovery and deliver sustainability benefits over the long term.”
FLS – KREBS heavy-media cyclones
Traditional heavy-media vessels can be inefficient separating fine material and their maintenance requirements are both costly and time consuming. KREBS heavy-media cyclones offer an alternative, delivering high-efficiency and relatively inexpensive separation of mineral particles from gangue using a fine magnetitewater medium.
FLS heavy-media cyclones boast exceptional efficiency thanks to various design features incorporated from the KREBS D26B cyclone, the industry’ s standard high-capacity cyclone as well