Berenguela Metallurgy

Aftermath has started a comprehensive metallurgical test work program using composite samples of silver-copper-manganese mineralization from Berenguela. Sixteen composite samples weighing over 6 tonnes in total were selected from Aftermath’s metallurgical drilling program, based on geometallurgical domains to cover all mineralization types encountered, and delivered to KCA's lab. The test program is being performed by Kappes Cassiday and Associates ("KCA") at their facility in Reno, Nevada, and will build on their previous metallurgical work carried out in 2010 on behalf of Silver Standard Mining.

Historic work, which is currently being verified by KCA on behalf of Aftermath, focused on recover the copper, iron, zinc, and manganese, as follows: a) Direct electrowinning or solvent extraction / electrowinning of the copper. b) Removal of iron by neutralization and air sparging, followed by thickening / filtration to remove the iron precipitate for discard. c) Precipitation of the zinc as zinc sulphide using sodium hydrosulphide, followed by thickening / filtration to recover the zinc sulphide as a marketable product. d) Recovery of manganese in a variety of forms depending on markets: - Manganese metal by electrolysis (EMM). - Manganese sulphate by crystallization, filtration, drying. - CMD powder by electrolysis. - EMD by more sophisticated electrolysis. The current work is concentrating on crystalline manganese sulphate as a potential co-product to Ag, Cu and Zn.

2024: Initial Results From KCA

In February 2024, KCA successfully produced battery grade 99.98% pure manganese sulphate crystals from a high-grade composite sample of Berenguela mineralization which assayed 31.9% MnSO4 (High purity manganese sulphate monohydrate or "HPMSM"). The test work involved only hydrometallurgical processes and no electrowinning was required for purification. The tables below contain results for the head assay grade of the composite test sample and the final MnSO4 analysis.

High Purity MnSO4 Analysis

  Ag As Al B Ba Be Bi Ca Cd Co Cr Cu Fe K
Units ppm ppm ppm ppm ppm ppm ppm ppm ppm ppm ppm ppm ppm ppm
98002  <1 <1 1 <1 8.0 < 1.0 <1 31.4 <1 <1 <1 <1 <1 <1
  Li Mg Mn Mo Na Ni Pb Sb Se Sr Ti Tl V Zn
Units ppm ppm % ppm ppm ppm ppm ppm ppm ppm ppm ppm ppm ppm
98002  <1 10.5 31.9 <1 36.8 1.3 <1 <1 <1 3.6 <1 <1 <1 3.3

Composite Sample, Average Head Assay Grade

  Ag As Al B Ba Be Bi Ca Cd Co Cr Cu Fe K
Units ppm ppm % ppm ppm ppm ppm % ppm ppm ppm % % %
98002: 138.6 115.4 17.9 40.6 9,054 < 1.0 5.5 5.1 3.3 33 36.6 1.58 6.38 1.37
  Li Mg Mn Mo Na Ni Pb Sb Se Sr Ti Tl V Zn
Units ppm % % ppm ppm ppm ppm ppm ppm % ppm ppm ppm ppm
98002: 15.1 1.22 19.1 10.2 3,726 9.8 526 4.04 85.9 1.39 891 229 34.6 4,133

As of February 2024, KCA is still carrying out testwork hence it's not possible to currently give an accurate Mn recovery, however they estimate that Mn recovery is likely greater than 90% in the flow sheet used in this testwork.

Figure 1. High purity MnSO4 prepared by KCA from Berenguela composite sample.

The objective of the program, which complements the prior metallurgical test work, is to refine the flowsheet routes and to outline approximate plant costs for a planned preliminary economic analysis ("PEA"). The work includes:

  • crushing and splitting;
  • pressure filtration tests;
  • creation of a standard solution for subsequent processing steps;
  • removal of iron from primary leach solution;
  • leach tests to determine the conditions (oxidation, cyanide level & consumption, leach time) for optimum silver recovery;
  • SX/EW tests for recovery of copper from the primary leach solution;
  • sulphide precipitation and recovery of zinc;
  • characterization of purified solution to identify other trace impurities and remove them if necessary;
  • MnSO4 crystallization processes and preparation of MnSO4 to send to outside groups for evaluation.

A full overview of the historic work completed by KCA is available in the Berenguela NI43-101 resource report filed on this website here.

What Is Manganese Sulphate Monohydrate?

High purity manganese sulphate monohydrate (HPMSM) is a pale pink inorganic chemical, with the formula MnSO4.H2O, which is in demand as a source of manganese for the battery manufacturing industry. Pure crystals of MnSO4.H2O contain 32% manganese, so one tonne of manganese metal yields 3 tonnes of HPMSM. Most is produced by dissolving a source of manganese metal in acid - such as the Ag-Cu-Mn oxide mineralization found at Berenguela- and then purifying the resulting liquid to reduce impurities and contaminants to the 100-200ppm range. China currently accounts for roughly 90% of global HPMSM production.