The report presents a conceptual processing route designed for 2 Mtpa throughput to produce separate lead and zinc concentrates from the Lagoa Salgada deposit.
Report context
The NI 43-101 Technical Report and Preliminary Economic Assessment for the Lagoa Salgada Project, Setúbal District, Portugal, prepared for Ascendant Resources Inc., includes a processing section based on existing metallurgical testwork (Chapter 13) and benchmark experience from Aljustrel and Neves-Corvo operations in the Iberian Pyrite Belt. The flowsheet, process design criteria, major equipment, and labour requirements are conceptual in nature and derived from project schedule data and operating parameters typical of Iberian Pyrite Belt operations.
Processing route
Crushing and grinding
The conceptual flowsheet envisions three stages of crushing: primary, secondary, and tertiary. Run-of-mine material is delivered by truck to the primary crusher or stockpile. Crushed material is conveyed via apron feeder and overland conveyor to a crushed material stockpile. Grinding comprises a primary ball mill (5.1 m × 6.3 m) operating in closed circuit with three cyclones (520 mm diameter). Overflow from primary cyclones feeds the secondary mill sump, with secondary cyclones (250 mm diameter) producing the final grinding product for flotation.
Lead flotation area
The grinding product passes through two conditioning stages , pulp aeration followed by collector addition. Pulp is pumped to a coarse rougher flotation consisting of four 100 m³ flotation cells. Rougher concentrate and first cleaner tailings combine as feed to regrind, passing through cyclones and two SMD mills. The regrind product is fed to a DPR (perhaps "differential" or "regrind" flotation) stage. Three stages of cleaner flotation produce the final lead concentrate, which is thickened to 65–70% solids and filtered to 9–11% moisture before stockpiling.
Zinc flotation and regrind area
Final tailings from lead flotation feed the zinc circuit, passing through three conditioning stages: pH regulation with lime, activation with copper sulphate, and collector addition. Pulp feeds a rougher flotation bank, with rougher concentrate sent to regrind via two SMD mills in reverse closed circuit with cyclones. Three cleaner flotation stages produce the final zinc concentrate. DPR is performed on reground material in three flotation cells; DPR concentrate joins first cleaner feed, while tailings combine with rougher tailings as final plant tailings sent to paste fill or tailings storage facility.
Dewatering and reagents
Lead and zinc concentrates are thickened to 65–70% solids and pressure filtered to 9–11% moisture. Reagents include flotation frothers, promoters, depressants, activators, pH regulators, and flocculants, with dedicated feeding, mixing tanks, and metering pumps.
Tailings, water, and utilities
Final plant tailings comprise first zinc cleaner tailings combined with zinc rougher tailings, destined for paste fill or the Tailing Management Facility. Plant water systems include fresh water, process water, fire water, and gland seal water, with recirculation from thickener and filter overflow. Utilities include grinding media storage, dust collection, air blowers and compressors, an assay laboratory, standby power, on-stream analysers, and a process control room.
Process plant equipment
Major equipment listed includes one primary ball mill (5.1 m × 6.3 m), three primary cyclones (520 mm), ten secondary cyclones (250 mm), four SMD mills, 15 flotation cells of 30 m³, six cells of 15 m³, four cells of 100 m³, two thickeners, and five conditioners. Process labour peaks at 73 persons in the first two years, comprising 50 mill operations staff and 23 maintenance personnel.
Key reported parameters
| Criteria | Units | Value | Basis |
|---|---|---|---|
| Plant throughput | tpa | 2,000,000 | Project schedule |
| Plant throughput | tph | 250 | Project schedule |
| Plant operations | years | 14 | Project schedule |
| Plant availability (crusher) | % | 65 | Benchmark IPB operation |
| Plant availability (other) | % | 92 | Benchmark IPB operation |
| Head grade Cu | % | 0.31 | Project schedule |
| Head grade Zn | % | 1.44 | Project schedule |
| Head grade Pb | % | 1.24 | Project schedule |
| Total Zn recovery | % | 80 | Benchmark IPB operation |
| Total Pb recovery | % | 65 | Benchmark IPB operation |
| Total Cu recovery (SW) | % | 80 | Benchmark IPB operation |
| Total Cu recovery (MS) | % | 25 | Benchmark IPB operation |
Project website: https://www.cerradogold.com/projects/lagoa-salgada
Project website: https://cerradogold.com/news-media/news-2025/cerrado-gold-to-acquire-ascendant-resources-inc
Technical qualifications
The process design criteria, flowsheet, and equipment selection are based on existing metallurgical testwork (detailed in Chapter 13 of the report) and on benchmark operating experience at Aljustrel and Neves-Corvo operations, both located in the Iberian Pyrite Belt. The report states that due to fluctuations in head grades of different minerals from initial years through the life of mine, the plant has been designed for a range of head grades rather than average values. No actual operating data from the Lagoa Salgada Project is reported; all processing parameters are conceptual design figures derived from project schedule and benchmark data.
Source: NI 43-101 Technical Report and PEA for the Lagoa Salgada Project, Setúbal District, Portugal, Ascendant Resources Inc., Chapter 17: Recovery Methods.
