goodbye "strong result"?, page-25

DoctorFouad, you seem concerned by the performance of the primary circuit but may not have tracked the improvements in the early stages. They have been quite confident about the primary circuit capability for a long while now.

From March 2017 Quarterly
Orocobre previously advised that production in the purification circuit was limited by thickenerresidence time post the purified product crystallisers. The thickener is the final step in the purificationcircuit prior to product entering the drying circuit. To solve this issue hydrocyclones have been installedto remove solids loading from the thickener and increase the overall capacity of this solids/liquidsseparation stage.Initial results indicate that the hydrocyclones are operating as expected and have removed around 50%of the solids that were previously overloading the thickener. The hydrocyclone project was completedon budget for US$1.45 million.Prior to installation of the hydrocyclones, the purification circuit has achieved a maximum throughputrate of 43 tonnes per day (tpd) and runs consistently at 35-40 tpd (73-83% of nameplate). Thehydrocyclones are expected to allow the purification circuit to achieve nameplate capacity ofapproximately 48 tonnes per day.The primary circuit consistently runs above nameplate capacity with a maximum achieved throughput of66 tpd, some 35% above nameplate.

The original presentations on stage 2 indicated that the plant would be a straight copy/paste of the existing plant, including purification circuit. Since then the concept has changed to a scaled up version of the existing plant with substantially increased pond area and without purification circuit. I am not aware of any suggestion that the basic flow sheet will be changed but I'm happy to be persuaded otherwise if you can point to a reference.

If the primary circuit has been shown capable of running substantially above nameplate, then lack of concentrated brine is an entirely plausible explanation for under performance on nameplate. The fact that the pond area is increasing at about 3.25x for a 2.4x increase in nameplate supports that view, even though they have not been explicit in saying that.

As for the liming constraint, they have not been explicit in their reports, but it was obviously discussed during an analysts site visit to the extent that it was raised in a webcast Q&A. Clearly a problem area that they are addressing - they are upping the capacity of the stage1 liming plant with a new reactor, and the stage2 and mobile liming plants add a further 600 l/s. Brine flow at stage 1 nameplate was to be around 180 l/s, so again they are looking to kick the problem out of the park.

While you may not see the logic, the liming is required for magnesium removal and it is the first step in the process - there can be no filling of ponds with raw brine. Flow of raw brine can increase only when the increased liming is on line - not yet. It will necessarily take some time for that brine to flow through the system, concentrate, and increase output at the other end. And at some stage they need to think about the filling schedule for stage2...