This test allowed to recover 28.1g (dry) of arsenic precipitate. Its characterization is shown in Table 5 below. Table 5 – Arsenic precipitate characterization. Sample Sample Type As content Cu Fe Mg Zn %wt. %wt. %wt %wt %wt SB1-PRE-AS Arsenic precipitate from SB1 16.9 4.39 11.6 13.9 5.65 This precipitate was directly amenable to vitrification as described in the following section. 3.3 GlassLock Vitrification: Product Quality and Environmental Compliance Both processing by-products (EC1 trioxide by-product and SB1 precipitate) were successfully vitrified. Arsenic in glass results and TCLP results are shown in Table 6. Table 6 – Glass formulation results Value Units Glass 1 Glass 2 From EC1 Pyrolysis Byproduct From SB1 Precipitation Byproduct TCLP result mg As/L 3.80 3.02 As in Glass %wt. 17.7 7.96 4. COMPARATIVE DISCUSSION: PYROLYSIS VS. PRECIPITATION 4.1 Process Comparison Table Table 7 – Process Comparison Table Aspect Pyrolysis approach Precipitation approach Feed Type Solid concentrate Acidic process solution Main Reagents (Arsenic capture) SO₂ (pyrolysis), O₂ (oxidation) FeCl₃, MgO As Removal (%) 99.3–99.6 99.9 By-product As₂S₃ (then As₂O₃) Fe-As oxyhydroxide Vitrification Feed As₂O₃ Fe-As precipitate Glass As (%wt) 15–18 8 TCLP As (mg/L) 3.3–3.8 3.02 Metal Recovery Cu, Au, Ag enriched in calcine Not applicable (solution treated) Scalability Proven at pilot scale Designed for full-scale (600 m³/d)
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