Zincore Metals' August 2013 prefeasibility study for the AZOD zinc oxide project in Cusco, Peru, crushes Accha and Yanque ore to minus 3 mm, fumes it in three rotary kiln lines and refines the fume by leaching, purification and electrowinning.
The NI 43-101 Technical Report on a Preliminary Feasibility Study for the AZOD Zinc Oxide Project, Cusco, Peru, was prepared by AMEC and Metallicon Process Consulting for Zincore Metals Inc. with an effective date of August 6, 2013. The base case combines a pyrometallurgical plant, which reductively roasts zinc-lead oxide ore from the Yanque and Accha deposits into a zinc-lead oxide fume, with a conventional hydrometallurgical refinery that turns the fume into zinc slabs and a lead sulphate residue by-product. Metallicon set the pyrometallurgical design from its 2010, 2011 and 2013 testwork. ThyssenKrupp sized the main equipment, and AMEC finalized it. The refinery design draws on Metallicon's 2013 testwork and Mintek simulations.
Critical Data
| Parameter | Value | Unit | Notes |
|---|---|---|---|
| Report effective date | August 6, 2013 | Not applicable | AMEC and Metallicon for Zincore Metals Inc. |
| Crushing | 3,683 t/d at 232 t/h | Not applicable | 67% availability, campaign crushed |
| Crushed product | Minus 3 | mm | Separate Yanque and Accha fine ore storage |
| Kiln feed | 176 | t/h | Two Yanque lines (102 t/h) and one Accha line (74 t/h) |
| Rotary kilns | 4.6 m inner diameter x 95 m | Not applicable | About 1,050°C |
| Pelletizers | 7.6 | m diameter | Zinc sulphate binder |
| Reductant | Anthracite, 3.5 to 6.5 mm | Not applicable | Dolomite added to Yanque feed |
| Pilot plant indication | About 95% Zn recovery at about 60% Zn fume grade | Not applicable | Lead recovery above 97% |
| Products | Zinc slabs (main), lead residue (by-product) | Not applicable | Transport to the coast |
| Plant location | 2 km from the Yanque pit | Not applicable | Ore trucked in 30 t trucks |
Overview
The pyrometallurgical steps are crushing to 100% minus 3 mm, pelletizing the ore with anthracite (Accha) or anthracite and dolomite (Yanque), and fuming in Waelz rotary kilns, with the fume cooled and captured in a baghouse. The hydrometallurgical steps are dehalogenation of the fume, neutral and acid leaching, cold and hot purification of the zinc sulphate solution, electrowinning in a tank house, melting and casting of zinc slabs, and dewatering and dispatch or pond storage of the lead sulphate residue.
According to the report, Phase 1 pyrometallurgical tests at IMN gave zinc recoveries of 88.51% and 89.36%, with lead recovery above 97%. Pilot work gave a classic grade-recovery curve suggesting about 95% zinc recovery at a fume grade of about 60% zinc. Because the Yanque and Accha mineralogy differs, separate recoveries were set for each mine.
Key Process Stages
Crushing. Run-of-mine ore arrives by 30 t truck and is tipped into a 270 t dump hopper with a 300 mm grizzly, or into a drying storage area. An apron feeder and grizzly feed a jaw crusher. A double-deck banana screen sends material over 11 mm to a secondary cone crusher. A tertiary Barmac B9100SE vertical impact crusher closes the circuit with a double-deck screen. Minus 3 mm product goes by bucket elevator to separate fine ore silos of 2,300 m³ (Yanque) and 900 m³ (Accha).
Mixing and pelletizing. Accha fines are blended with anthracite in a helical mixer, and Yanque fines with anthracite and dolomite in two mixers. Each mixer feeds a 7.6 m pelletizer using zinc sulphate solution as binder. The pellets are blended with coarse anthracite before entering the kilns.
Waelz kilns. Three kiln lines, each 4.6 m in internal diameter and 95 m long, operate at about 1,050°C. Zinc and lead volatilize and report to the off-gas as an oxide fume, which is cooled and collected in a baghouse. The remaining slag is discharged and stored.
Fume refining. The fume is dehalogenated, then leached in neutral and acid stages. The zinc sulphate solution is purified in cold, hot and polishing stages. Electrowinning produces zinc cathodes, which are melted and cast into slabs. Zinc powder is made by air atomization. A bleed of spent electrolyte goes to neutralization, zinc precipitation and re-leach, and gypsum is disposed of.
Additional Interesting Data and Summary
The plants are to be controlled by PLC systems from central control rooms, with operators able to change set points and switch motors from graphical consoles. The level of automation is in line with industry standards.
In summary, the 2013 AZOD PFS treats low-grade zinc oxide ore by Waelz fuming, the route often used for zinc-bearing residues. It concentrates zinc and lead into a fume in three large rotary kilns, then produces slab zinc on site through a conventional leach, purification and electrowinning refinery.
Key Processes
- Three-stage crushing to minus 3 mm with vertical impact tertiary crushing
- Blending with anthracite (and dolomite) and pelletizing
- Waelz rotary kiln fuming with baghouse fume capture
- Fume dehalogenation
- Neutral and acid leaching
- Cold, hot and polishing purification
- Zinc electrowinning, melting and casting
- Lead sulphate residue by-product
Source: Zincore Metals Inc., AZOD Zinc Oxide Project, Cusco, Peru, NI 43-101 Technical Report on a Preliminary Feasibility Study, AMEC and Metallicon, effective date August 6, 2013.
Earlier report summaries
Earlier versions of this profile, based on older technical reports, are retained below for source traceability. Dates and figures reflect each report’s own effective date and are superseded by the current information above.
AZOD Zinc Oxide Project — 2011 Technical Report
This report outlines the proposed processing route for the AZOD Zinc Oxide Project in Cusco, Peru, as defined in the 2011 preliminary economic assessment, incorporating pyrometallurgical and hydrometallurgical design criteria based on pilot, laboratory, and bench-scale testwork.
Report context
The AZOD Zinc Oxide Project is located in Cusco, Peru, and the processing concept described herein forms part of a NI 43-101 Technical Report on a Preliminary Economic Assessment (PEA) completed in October 2011. The process design criteria were developed for the recovery of zinc and lead from run-of-mine ore, with supporting data derived from pyrometallurgical pilot and laboratory tests, as well as bench-scale leach testwork on fume for the initial hydrometallurgical step. The report presents a simplified process flowsheet and major design criteria, but does not include full economic or operational details.
Processing route
Simplified flowsheet
The basis of the processing concept for the AZOD Project used in the AZOD PEA is shown in a simplified process flowsheet (Figure 17-1 in the original report). The flowsheet begins with run-of-mine (ROM) ore and includes both pyrometallurgical and hydrometallurgical stages. The figure is referenced but not reproduced here.
Pyrometallurgical stage
The pyrometallurgical stage is designed to treat the ore through crushing, fine ore storage, and a rotary kiln. Key design criteria include a daily ore throughput of 4,040 tonnes, with 332.5 operating days per year. The kiln is sized at 60 metres in length and 3.8 metres inner diameter, with an availability of 91%. Gas cooling and baghouse systems are included for fume capture. Anthracite ratios are specified at 2.7 and 3.0 kg per kg of zinc content for the Accha and Yanque ore types, respectively. The kiln operates at a temperature of 1,150°C, with no binder addition (reported as "No" for binder use). Residence times are 5 to 6 hours, depending on ore type. Fume production is targeted at 430 tonnes per day, with a blend quality of 69.6% for combined zinc and lead, and 82% for combined zinc oxide and lead oxide. Recovery of zinc and lead into the fume is reported as 92.4% and 97%, respectively. Slag production is estimated at 2,046 tonnes per day.
Hydrometallurgical stage
The hydrometallurgical stage is designed to process the fume product from the pyrometallurgical stage. Initial testwork included bench-scale leach tests on fume for the dehalogenation step, while downstream design criteria were assumed based on Metallicon and AMEC’s experience with conventional zinc refineries processing zinc sulphate solutions. Vendor recommendations were also considered. The stage includes dehalogenation, neutral leaching, acid leaching, cold and hot purification, and electrolysis. The refinery availability is set at 97%. The design includes a dehalogenation feed rate, pH control, and residence time; neutral leach with spent electrolyte flow and residence time; acid leach with defined feed rate and residence time; cold and hot purification stages with specified temperatures and residence times; and electrolysis with a defined number of cells, cathodic current density, and energy efficiency. The ratio of spent to pure solution, power consumption in cells, and slab zinc and residue lead production rates are also specified, though exact numerical values for many hydrometallurgical parameters are not fully listed in the available table.
Key reported parameters
| Parameter | Units | Value |
|---|---|---|
| Annual throughput – ore | t/a | 1,343,145 |
| Annual operating days | days | 332.5 |
| Daily throughput – ore | t/d | 4,040 |
| Crusher availability | % | 70 |
| Fine ore storage capacity | days | 1 |
| Size fine ore P100 | mm | 3 |
| Kiln size, length / inner diameter | m | 60 / 3.8 |
| Kiln availability | % | 91 |
| Gas cooling / baghouse lines | – | 2 |
| Anthracite ratio (Accha / Yanque) | kg anthracite / kg Zn content | 2.7 / 3.0 |
| Kiln temperature | °C | 1,150 |
| Binder | – | No |
| Residence time (Accha / Yanque) | h | 5 / 6 |
| Fume production | t/d | 430 |
| Fume quality (Zn+Pb) | % | 69.6 |
| Fume quality (ZnO+PbO) | % | 82 |
| Recovery in fume (Zn / Pb) | % | 92.4 / 97 |
| Slag production | t/d | 2,046 |
| Refinery availability | % | 97 |
| Overall zinc recovery | % | Not specified in available data |
Project website: https://finance.yahoo.com/news/zincore-announces-completion-filing-positive-012542040.html
*Note: Values for hydrometallurgical parameters such as feed rates, pH, residence times, temperatures, flowrates, cell quantities, current density, and power consumption are referenced in the original table but were not fully populated in the available extract.*
Technical qualifications
The process design criteria incorporate data from pyrometallurgical pilot and laboratory tests, as well as fume bench-scale leach tests for the initial hydrometallurgical step. However, downstream hydrometallurgical design criteria have been assumed based on Metallicon and AMEC’s experience with similar conventional zinc refineries, not on site-specific testwork. This introduces uncertainty in the applicability of these assumptions to the AZOD ore and fume characteristics. Vendor recommendations were also considered, but the report does not specify which equipment or suppliers were involved. The report notes that the PEA is preliminary in nature and does not include full economic analysis, and the flowsheet is simplified, meaning that detailed engineering and optimization have not been performed.
Source: AZOD Zinc Oxide Project, Cusco, Peru, NI 43-101 Technical Report on a Preliminary Economic Assessment, Project No. 167634, October 2011, Section 17.0 Recovery Methods.
