QUEBEC CITY, QUEBEC -- (Marketwire) -- 03/27/13 -- Clifton Star Resources Inc. ("Clifton Star" or "the Corporation") (TSX VENTURE: CFO)(FRANKFURT: C3T) is pleased to report that it has received the results of a laboratory study conducted by SGS Minerals that succeeded in producing high grade gold concentrates from mineral samples of the Duparquet Project.
Six samples from the Duparquet Project were treated using a cleaner flotation scheme developed by SGS Minerals to recover a high grade gold concentrate. The tests were performed as "locked cycle" tests to simulate full scale plant operating conditions. Cleaner flotation tests were conducted to investigate the recovery of gold in a sulphide concentrate for the purpose of toll smelting as an alternative to the operation of a pressure autoclave (POX), which is part of the mill process flowsheet used in the recently published preliminary economic assessment study ("PEA") on the Duparquet Project (press release dated January 15, 2013).
-- The gold grade of the cleaner concentrates ranged from 39 g/t Au to 84 g/t Au and the sulphur grade ranged from 21% S to 36 % S. These grades of gold and sulphur are amenable to toll smelting through copper smelting operations.-- The average overall gold recovery was 89.6%. This overall recovery is close to the 93% overall gold recovery obtained with the pressure oxidation treatment of lower grade flotation concentrates.-- The production of high grade concentrates raises the possibility of avoiding the capital and operating cost of building a full scale pressure oxidation pre-treatment plant for the Duparquet Project. The capital cost of the POX circuit in the Tenova Bateman cost study, presented as part of the recent PEA, was $157.5 Million out of an estimated cost of $270 Million for the entire Mill. This cost would no longer be required but there would be some much lower additional costs for cleaner flotation, concentrate filtering, drying and shipping. Similarly, the operating cost for the POX area of the mill was estimated at $6.67/t of ore. This cost would not be required but would be substituted by the lower operating costs for concentrate preparation and shipping.
A rougher concentrate was recovered following the conditions applied in previous test work. In five out of six samples, only one cleaning stage was sufficient to produce concentrate grades exceeding 35 g/t in gold. Arsenic content averaged 1.1 % for the six samples and would imply a penalty since most smelters accept a 0.4% content.
The reagent consumptions for cyanidation of the flotation tailing were 0.14 - 0.47 kg NaCN/t of ore and 0.54 - 0.81 kg CaO/t of ore. These values are very low and indicate that cyanidation of the tailings will consume minimum amounts of chemical reagents.
Pre-Feasibility Study on the Duparquet Project:
Clifton Star has started a Pre-Feasibility Study on the Duparquet Project and part of it will compare the relative benefits of the two possible process treatments, either a POX circuit, as used in the PEA, or production of high grade gold concentrates.