Scandinavian Minerals Announces Positive Pilot Plant Results for Kevitsa Nickel-Copper-PGE Property
Thursday, July 12th, 2007
Scandinavian Minerals Limited announce positive results of Pilot Plant testing for its 100%-owned Kevitsa nickel-copper-PGE property in Finland. The Pilot Plant program has confirmed that good quality, smelter-grade nickel and copper concentrates can be produced from Kevitsa ore by conventional flotation methods.
Peter Walker, President and CEO of Scandinavian Minerals commented “The Pilot Plant results clearly show that good quality, smelter-grade concentrates can be produced from the Kevitsa ore at commercially acceptable levels of recovery. The attaining of very low levels of magnesia in the nickel concentrate and the elimination of TETA from the flotation process represent two additional important achievements.”
The Pilot Plant tests were undertaken at the Mineral Processing Laboratory of the Geological Survey of Finland (GTK MinProc). A bulk sample totalling 575 tonnes of ore was processed in three phases from September 2006 to February 2007, the first two phases consisting of process optimisation, the third phase incorporating improvements made in the previous phases.
The bulk sample consisted of the nickel-copper-PGE ore type that forms the main orebody at Kevitsa and was mined in summer 2006. The average grade of the ore processed in phase 3 was 0.448 % copper, 0.360% nickel, 1.85 % sulphur, 0.329 g/t platinum, 0.336 g/t palladium and 0.186 g/t gold, with 0.06 % nickel being contained in silicate minerals.
Nickel flotation yielded a range of smelter-grade concentrates averaging 12.2% nickel, within a range varying from 9.4% to 17.3% nickel. Sulphide nickel recovery ranged from 77.4% to 80.5% and averaged 78.8%. Recoveries with respect to total nickel (sulphide nickel plus silicate nickel) ranged from 64% to 67% and averaged 65.3%. The nickel concentrate also contained an average 10 grams/ton platinum at 55% recovery, 7.7 grams/ton palladium at 38% recovery and 1.6 grams/ton gold at 10% recovery.
GTK MinProc estimates that total nickel recovery for the average ore at Kevitsa will be between 70% and 72%. The level of non-recoverable (silicate-bound) nickel in the bulk sample was higher than the calculated orebody average: the phase 3 bulk sample contained 605 ppm (parts per million) silicate nickel, equivalent to 17% of total nickel. This compares with an average, supported by extensive drill core analyses, of 275 ppm silicate nickel for the main orebody as a whole, or 9% of total nickel
recovery: sulphide nickel, recovery: total nickel
pilot plant, average 78.8% 65.3%
projected, average 78.8% 70%-72%
A further objective of the test work was to maintain a high iron to magnesia (Fe:MgO) ratio in order to maximise the attraction of the concentrate to smelters. In this regard, the test work produced outstanding results, with an average Fe:MgO ratio of 17.9, well above the targeted minimum of 4.5. This very high ratio will help to ensure that the Kevitsa nickel concentrate is especially attractive to nickel smelters.
Another notable achievement of the program was the elimination from the flotation process of several reagents, especially TETA (triethylene tetramine). In previous work TETA was used to suppress the flotation of pyrrhotite (iron sulphide) in the nickel circuit. The Pilot Plant work demonstrated that by adjusting flotation conditions, the use of TETA can be avoided. The elimination of TETA enhances the stability of the flotation process and represents an important cost saving.
Copper flotation yielded high-grade concentrates averaging 28.55% copper, at an average recovery of 78%. This represents a significant improvement on earlier mini-pilot results. A further 11% of the copper reported to nickel concentrate, bringing total copper recovery to 89%. The tests further demonstrated that nickel in the copper concentrate, could be maintained at a commercially acceptable level averaging 0.67%, below the typical penalty threshold of 0.8%. Nickel is considered a deleterious element in copper concentrate. The copper concentrate also contained around 4 grams/ton gold at 24% recovery.
copper recovery to copper concentrate, copper recovery to nickel concentrate, total copper recovery
pilot plant, average 78% 11% 89%
The Pilot Plant results will be incorporated into the ongoing Feasibility Study for Kevitsa. This Study was commenced in April 2007 and is being coordinated by St Barbara LLP (formerly St Barbara Consultancy Services) of London, UK. The metallurgical process has been developed by GTK MinProc. Plant engineering and design is being performed by Outotec Oyj. The Feasibility Study is expected to take approximately 12 months to complete.