Solaris Resources (TSX:SLS) Reports Results of Over 90% Copper and 80% Molybdenum From Metallurgical Test Work at Warintza Project

Figure 1: Metallurgical Drill holes. Source: Solaris Resources

Solaris Resources (TSX:SLS) (OTCQB:SLSSF) has reported new results from metallurgical test work at the Warintza Project in Ecuador, showing high recoveries of copper, molybdenum, and gold in rougher flotation, cleaner flotation, and locked cycle testing. The company commissions FLSmidth USA Inc. to perform all comminution and metallurgical flotation test work programs.

Mr. Daniel Earle, President & CEO, commented in a press release: “Warintza is blessed with simple metallurgy that readily returns high recoveries of critical minerals from standard flotation processes into high-grade concentrates free of deleterious elements. Historical testing reported high recoveries of over 90% for copper and 70% for gold; our testing has reproduced these results and established high recoveries for molybdenum of over 80% at a time when molybdenum prices recently eclipsed $30/lb due to structural supply issues in the sector.”

Highlights from the results are as follows:

  • High recoveries for copper (“Cu”), molybdenum (“Mo”) and gold (“Au”) in rougher flotation, cleaner flotation and locked cycle testing
  • Low reagent dosages and short flotation times over a wide range of pH levels, and requiring only moderate to coarse grind sizes for both supergene and hypogene samples
  • High copper concentrate grades expected from both supergene material at 40% Cu and hypogene material at 22% Cu with both concentrates containing in excess of 1 g/t Au 
  • High molybdenum concentrate grades expected to meet or exceed 51% Mo independent of feed type given excellent liberation of coarse grained molybdenite
  • For context, the Warintza Mineral Resource Estimate (“MRE”)¹ includes a molybdenum byproduct estimate containing 150 kt Mo grading 0.03% Mo (Indicated) and 130 kt Mo grading 0.01% Mo (Inferred), in addition to gold
  • Concentrates free of deleterious elements, with no significant values of arsenic, antimony, bismuth or mercury
  • Optimization testing with larger sample sizes planned for hypogene material aimed at further increasing recoveries

Metallurgical Test Work Program Scope

The metallurgical test work program at FLS included comminution grind studies on two master composites, ore characterization, grinding indices, rougher and cleaner flotation tests, locked cycle testing and variability rougher kinetics flotation tests. The objective of the test work was to evaluate the metallurgical flotation response of the master composites and variability samples, establish metal recoveries, evaluate if any deleterious elements were present, and assess whether clean, high-grade concentrates could be produced with industry standard processing practices and reagents.

Sample Selection

The metallurgical samples were taken from three drill holes specifically drilled for metallurgical test work. The hole depths range from 500m to 960m with sample selection ranging from 46m below surface to a depth of 450m. Seven samples which consisted of 20m intervals of half core were selected for the test work program for a total weight of 651kg of sample material. The samples were selected from the Warintza Central deposit to represent the mineralization, metal grades, and lithology type which formed the first pit phases of the MRE.

Table 1: Sample Selection

Met ID Hole ID From (m) To (m) Interval (m) Mineralization
S1_2 SLS-59 126 146 20 Supergene
S2_2 SLS-60 112 132 20 Supergene
S3_2 SLS-60 46 66 20 Supergene
P1_2 SLS-59 330 350 20 Hypogene
P2_2 SLS-61 428 448 20 Hypogene
P3_2 SLS-60 260 280 20 Hypogene
P4_2 SLS-61 280 300 20 Hypogene
      Total 140  

Table 2: Collar Location

Hole ID Easting Northing Elevation (m) Depth (m) Azimuth (degrees) Dip (degrees)
SLS-61 800191 9648065 1573 967 255 -72
SLS-60 800258 9648097 1559 873 190 -80
SLS-59 799765 9648033 1571 513 65 -70
Notes to Table 2: The coordinates are in WGS84 17S Datum.

The metallurgical samples were combined by mineralization type and classified as supergene and hypogene which formed two master composites (“MC”) for the flotation test work program. MC #1 represents the supergene material and MC #2 represents the hypogene material. Each MC was assayed to confirm the metal grades are within range of the grades expected in the first phases of a potential mine plan. The head grades for each MC can be found in Table 3.

Table 3: Master Composite Head Grade

Composite Head Grade
Cu, % Mo, % Au, g/t
MC #1 1.22 0.03 0.07
MC #1B 1.13 0.04 0.07
MC #2 0.66 0.03 0.06
MC#2B 0.58 0.03 0.07

Rougher Flotation Testing

FLS completed six rougher flotation tests on MC #1 and five rougher flotation tests on MC #2. In both composites, the copper recovery does not appear to be influenced significantly by pH, grind size, or collector dosages. The rougher flotation tests focused on primary grind size, pH, and collector dosage as the variables for influencing the flotation behavior. The collector used in all tests is Cytec Aero 8989 for copper and burner oil as a molybdenum collector. Below is a summary of MC #1 and #2 tests at various grind sizes and pH.

Table 4: Rougher Recoveries and Grades

MC #1 – Supergene
Actual Grind Size, µm pH Recovery Grade
Cu, % Mo, % Au, % Cu, % Mo, % Au, g/t
117 6.8 91.7 89.3 80.3 9.63 0.24 0.38
122 8.5 91.7 88.6 78.2 7.74 0.19 0.43
143 8.5 91.0 90.7 77.3 12.32 0.31 0.65
144 9.8 91.0 92.3 68.2 13.41 0.32 0.85
144 9.2 91.9 91.5 71.7 12.95 0.30 0.92
167 8.8 91.1 86.6 74.0 12.53 0.30 0.62
Average 91.4 89.8 75.0      
MC #2 – Hypogene    
Actual Grind Size, µm pH Recovery Grade
Cu, % Mo, % Au, % Cu, % Mo, % Au, g/t
98 8.5 95.0 94.4 78.0 4.39 0.20 0.38
129 8.6 95.1 91.6 78.8 4.37 0.20 0.39
177 8.6 94.5 93.9 78.7 4.32 0.18 0.39
147 9.4 95.5 91.4 70.0 4.44 0.15 0.45
147 8.9 94.8 91.6 68.8 4.78 0.18 0.47
Average 95.0 92.6 74.8      

Cleaner and Locked Cycle Flotation Testing

Batch cleaner tests were conducted to ensure that bulk concentrates could be produced without significant cleaner losses. One cleaner test was conducted on MC #1 and four cleaner tests were conducted on MC #2, with regrind size being the most significant variable tested. A second set of master composites were created with the same blend of variability samples as the original master composites labeled MC #1B and MC #2B and were used for seven locked cycle tests and copper-molybdenum separation tests. Batch cleaner and locked cycle testing produces high recoveries for the supergene composite of 90% Cu and 83% Mo and hypogene composite of 89% Cu and 75% Mo. FLS concluded that higher recoveries could be achieved for MC #2 and #2B with reagent optimization, which will be incorporated into the next phase of testing.

Copper-Molybdenum Concentrate Separation Test

The second set of master composites, MC #1B and MC #2B, were used for the copper-molybdenum separation of the bulk concentrates. The test work only included a rougher stage molybdenum float that was carried out for both MC #1B and MC #2B due to the size of the remaining sample. The molybdenum separated from the copper successfully into a rougher concentrate for both master composites given excellent liberation characteristics and coarse grain size for molybdenum, with the majority of grains by mass > 200 microns in size. Flotation testing of the supergene samples produced a copper concentrate grading approximately 40% Cu and containing in excess of 1 g/t Au. Flotation testing of the hypogene samples produced a copper concentrate grading approximately 22% Cu and containing in excess of 1 g/t Au. Molybdenum concentrate grades at 51% Mo independent of feed type.


  1. Refer to Solaris’ technical report titled, “NI 43-101 Technical Report for the Warintza Project, Ecuador” with an effective date of April 1, 2022, prepared by Mario E. Rossi and filed on the Company’s SEDAR profile at



The above references an opinion and is for information purposes only. It is not intended to be investment advice. Seek a licensed professional for investment advice. The author is not an insider or shareholder of any of the companies mentioned above.

By Matthew Evanoff

I specialize in the mining industry, focusing on top global mining stocks. My reporting covers the latest industry news, company/project developments, and profiles of key players. With a degree in finance and economics from the University of Toronto, I've contributed to a wide range of industry publications. Beyond my professional pursuits, I have a keen interest in global business and a love for travel.

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