The April 2026 technical report on Santacruz's Zimapán mine in Hidalgo, Mexico describes a 3,000 t/d plant with jaw and cone crushing, three ball mill circuits, lead-copper bulk flotation with differential separation and cyclone-built tailings dams.
Zimapán is a silver, lead, zinc and copper mine in Hidalgo State, Mexico, operated by Santacruz Silver Mining Ltd. The NI 43-101 technical report has an effective date of December 31, 2025 and a report date of April 30, 2026. The San Francisco Processing Plant uses conventional crushing, grinding and flotation to produce three concentrates: lead, zinc and copper. It can currently process up to 3,000 t/d of fresh feed, which is a blend of material from the Monte, Carrizal and Limo de Toro mines. Feed from the separate mining areas is stockpiled separately at the mill, and a loader blends it by combining stockpile material in the crusher feed hopper. Each of the three concentrates is sold in bulk to smelters.
Critical Data
| Parameter | Value | Unit | Notes |
|---|---|---|---|
| Plant capacity | Up to 3,000 | t/d | Fresh feed |
| Crusher product | 3/8 | in P80 | Jaw, then two cone crushers |
| Primary jaw crusher | 24 x 36 | in | Discharges to one of three bins |
| Cone crushers | 2 | Metso HP300 | Secondary and tertiary |
| Ball mills | 3 | Not applicable | In parallel, single stage |
| Mill sizes | 10 ft 8 in x 11 ft; 9 ft x 12 ft; 10.5 ft x 14 ft | Not applicable | 600, 500 and 1,100 hp |
| Grind size | About 110 | µm P80 | Plant measure: 68% passing 75 µm |
| Cyclones | 2 | Krebs D20 per mill | One operating, one standby |
| Lead-copper roughers | 5 | cells | Two Wemco 300 ft3, three Wemco 1000 ft3 |
| Copper-lead separation | 7 | Denver 50 ft3 cells | Lead floated, copper depressed |
| Zinc roughers | 6 | cells | Four Denver 300 ft3, two Wemco 300 ft3 |
| Zinc rougher scavengers | 4 | Wemco 300 ft3 cells | Follows rougher |
| Zinc cleaning | 3 | stages | Plus a column |
| Lead thickener | 20 | ft diameter | Two Clever MSR filter presses |
| Copper and zinc thickeners | 30 | ft diameter | Press and drum filters |
Overview
The plant follows a typical lead, copper and zinc flotation circuit with crushing to reduce mill feed to 3/8 inch. Feed is ground in one of three primary ball mills to a feed size P68 of 75 µm, which is about P80 110 µm. It is conditioned and subjected to lead-copper bulk flotation. The lead-copper tails go to the zinc rougher circuit. Lead-copper rougher concentrate is upgraded in cleaner flotation and goes through a lead-copper differential circuit in which copper is depressed and lead is floated to a final lead concentrate. The zinc rougher concentrate is cleaned in the zinc cleaner circuit.
Key Process Stages
Crushing
A 24 inch by 36 inch jaw crusher discharges by conveyor to one of three bins, and vibratory feeders send material to one of two double deck vibratory screens. First deck oversize feeds a Metso HP300 secondary cone crusher, and lower deck oversize feeds a second HP300 as the tertiary crusher. Undersize goes to one of three fine ore bins. The circuit makes a 3/8 inch P80.
Grinding
Three single stage ball mills run in parallel, each in closed circuit with two Krebs D20 cyclones, one operating and one standby. The first mill is 10 ft 8 in by 11 ft with 600 hp, the second 9 ft by 12 ft with 500 hp and the third 10.5 ft by 14 ft with 1,100 hp. Each is fed by one of two SRL pumps.
Lead and copper flotation
Grinding product goes to the lead conditioner tank, where MCM 8020 collector, a zinc sulphate and cyanide mixture called Mixtura, and frother are added. A lead-copper flash flotation cell comes first, then five rougher cells. Rougher concentrate from the first two cells goes to a single Denver 500 ft3 cleaner and a pair of cleaner scavenger cells in series, whose tailings return to the middle of the rougher bank. Cleaner and flash concentrates go to the separation circuit of seven Denver 50 ft3 cells. Its concentrate reports to the lead thickener and its tails to the copper thickener.
Zinc flotation
Lead-copper rougher tailings go to two conditioning tanks where copper sulphate, lime slurry and frother activate sphalerite. The zinc rougher circuit has four Denver and two Wemco 300 ft3 cells, followed by four Wemco 300 ft3 scavenger cells. Zinc cleaning has three stages of single 500 ft3 cells, with each concentrate moving forward and tailings moving back, and the first cleaner tails go to the scavenger feed. A zinc cleaner flotation column makes the final concentrate. Rougher tailings go to final tailings.
Concentrate dewatering and tailings
Lead concentrate is thickened in a 20 ft thickener and filtered by two Clever MSR filter presses with 800 mm plates. Copper concentrate is thickened in a 30 ft thickener and filtered by a single Clever MSR press with 1200 mm plates. Zinc concentrate is thickened in a 30 ft thickener and filtered on an 8 ft by 10 ft drum filter. Flotation tailings go to two water recovery thickeners and then by gravity to the tailings storage facility (TSF) No. 9. A hydrocyclone at the main dam crest splits coarse and fine tailings, and the coarse fraction is hydraulically placed as dam fill by the downstream method.
Additional Interesting Data and Summary
TSF No. 9 is the only active facility. It is a valley fill design with a north main dam and a south back dam built of cyclone tailings fill and rockfill, with a buttress at the toe of the north dam. Eight decommissioned TSFs lie upstream. The report says TSF No. 9 was projected to reach full storage capacity in 2024, with expansion in design and permitting.
The water system includes a seepage collection sump at the downstream toe, a sump between TSF No. 9 and TSF No. 7, engineered diversion channels, an underground tunnel diverting the San Miguel drainage, and two reinforced concrete spillways that preserve the minimum freeboard.
Key Processes
- Jaw crushing and two cone crushing stages with double deck screens
- Three parallel ball mills in closed circuit with cyclones
- Lead-copper bulk flotation with flash and cleaner stages
- Copper-lead differential flotation
- Zinc activation, rougher, scavenger and column cleaner flotation
- Filter press and drum filtration of concentrates
- Cyclone-built tailings dam
Source: NI 43-101 Technical Report, Zimapan Mine, Hidalgo State, Mexico, April 30, 2026.
Project website: Zimapan Mine
