Abcourt Mines' January 2019 update to the technical feasibility report for the Abcourt-Barvue zinc-silver deposit in Barraute Township, Québec, makes a 53.4% Zn concentrate carrying about 741 g/t silver. A pyrite concentrate is floated off and stored separately.
The Update to the Technical Feasibility Report on the Abcourt-Barvue Deposit was prepared for Abcourt Mines Inc. by PRB Mining Services and Bumigeme, with an effective date of January 15, 2019 and an issue date of January 18, 2019. The mill flowsheet is based on the latest URSTM laboratory test (AB-64), other available test data and Bumigeme's experience with similar operations. Abcourt and Barvue ores are blended to a mill head of 2.83% Zn and 51.79 g/t Ag. The plant treats 650,000 t a year at a nominal 1,800 t/d, with a design capacity of 1,956 t/d at 92% operating time. Design recoveries are 97.5% for zinc and 77.8% for silver.
Critical Data
| Parameter | Value | Unit | Notes |
|---|---|---|---|
| Report effective date | January 15, 2019 | Not applicable | PRB Mining Services and Bumigeme for Abcourt Mines Inc. |
| Annual ore | 650,000 | t | Nominal 1,800 t/d, design 1,956 t/d |
| Mill head grade | 2.83% Zn, 51.79 g/t Ag | Not applicable | Blended Abcourt and Barvue ore |
| Recovery | Zn 97.5, Ag 77.8 | % | Design |
| Zinc concentrate | 53.4% Zn, 740.6 g/t Ag | Not applicable | Zinc-silver concentrate |
| Crushing | Jaw crusher behind a 750 mm grizzly | Not applicable | 75 t lined hopper |
| Coarse ore bin | 600 t (8 h) | Not applicable | Covered, heated, insulated |
| SAG mill | 4.0 m x 5.484 m, 1,450 kW | Not applicable | Closed with a 20-inch cyclone |
| Ball mills | Two 3.048 m x 3.66 m, 590 kW each | Not applicable | Ten 250 mm cyclones (8 operating) |
| Zinc flotation | 50 m³ rougher and scavenger, 10 m³ cleaners | Not applicable | 35 m³ conditioner |
| Pyrite flotation | 50 m³ rougher, three 10 m³ scavengers | Not applicable | Final tails below 0.3% S |
| Concentrate filter | Horizontal pressure filter, 40 m², 18 plates | Not applicable | Fed from a 38 m³ surge tank |
| Reagents | H2SO4 4.4, CuSO4 0.395, KAX 0.018 | kg/t | Plus Percol 338, A-208 and F-507 |
Overview
Blended ore is crushed in a jaw crusher and stockpiled, then conveyed to a coarse ore bin. A SAG mill and two ball mills closed with cyclones grind the ore. A zinc flotation circuit (conditioner, rougher, scavenger and cleaners) makes a zinc-silver concentrate. A pyrite flotation stage on the zinc scavenger tails floats the residual sulphides into a concentrate stored in a secure sulphide cell. The remaining tailings are low enough in sulphur not to generate acid. The zinc concentrate is thickened, pressure filtered and trucked. An on-stream analyzer covers eight flotation streams.
Key Process Stages
Crushing and storage. A front-end loader feeds blended ore over an inclined grizzly with 750 mm openings, and a vibrating pan feeder draws it to the jaw crusher. The crusher's rated capacity is well above mill throughput because it was sized for the grizzly opening. An electromagnet protects the 914 mm conveyors. A cyclone and baghouse collect dust. The 6.8 m by 10 m coarse ore bin is heated and insulated against freezing.
Grinding. Two apron feeders under the bin feed the SAG mill, with feed rate controlled by a belt scale. SAG discharge is cycloned, and the overflow is pumped to a 10-cyclone pack closed with the two ball mills. A Delkor linear screen removes trash before flotation. Each ball size has its own bin, and ball loading chutes sit at the mill feed ends.
Zinc flotation. Conditioned pulp is floated in rougher and scavenger cells. Scavenger concentrate can be returned to the conditioner, and cleaner tails return to the head of the circuit.
Pyrite flotation and tailings. Zinc scavenger tails go through a 70 m³ conditioner to a 50 m³ rougher and three 10 m³ scavenger cells. The pyrite concentrate is pumped to a secure tailings cell. Final tails go to a 10 m thickener and then the tailings pond, and the thickener overflow is reclaimed.
On-stream analysis. A single analyzer head with two multiplexers assays eight streams sequentially. A full cycle takes 20 to 30 minutes, and the data allow sub-circuit recoveries to be calculated online.
Concentrate dewatering. The process description places the cleaner concentrate in a 6.0 m thickener, and the dewatering section describes a 9.8 m thickener at about 65% solids. Peristaltic pumps move the underflow to a 12-hour surge tank and then to the pressure filter. The filter cake drops to a storage pad and is loaded into trucks.
Additional Interesting Data and Summary
The mill building, 200 by 140 ft, houses grinding, flotation, services, reagent preparation and the electrical room. A 35/5 t overhead crane serves the grinding bay.
In summary, the 2019 Abcourt-Barvue feasibility update is a compact 1,800 t/d SAG-ball and flotation mill. It makes a high-silver zinc concentrate and adds a pyrite flotation step so that the final tailings do not generate acid.
Key Processes
- Jaw crushing and covered coarse ore bin
- SAG milling and two-ball-mill grinding with cyclones
- Zinc-silver rougher, scavenger and cleaner flotation
- Pyrite flotation for desulphurized tailings
- On-stream analysis of flotation streams
- Zinc concentrate thickening and pressure filtration
- Tailings thickening and segregated sulphide storage
Source: Update to the Technical Feasibility Report on the Abcourt-Barvue Deposit, prepared for Abcourt Mines Inc. by PRB Mining Services Inc. and Bumigeme Inc., effective date January 15, 2019.
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.
Abcourt-Barvue Property — 2014 Resources Evaluation Report
This report details proposed processing methods and past operational context for the Abcourt-Barvue property, based on historical technical studies.
Report context
This Resources Evaluation Report for the Abcourt-Barvue property, located in Barraute Township, Quebec, Canada, is dated 2014. The report acknowledges that a new Feasibility Study is required for sections concerning recovery methods, project infrastructures, market studies, environmental studies, capital and operating costs, and economic analysis. Information on processing presented in the report is derived from Genivar's 2007 technical report and is provided for preliminary reference only. The property has a recorded production history of 5,002,190 tonnes grading 38.74 g/t Ag and 2.98% Zn from open pit mining (1952-1957), and 632,319 tonnes grading 131.65 g/t Ag and 5.04% Zn from underground mining (1986-1990).
Processing route
2007 Genivar proposed design
In 2007, Genivar proposed a mill processing rate of 1,800 tonnes per day of ore. The proposed treatment method involved a two-step process combining cyanidation and flotation. The ore would first pass through a cyanidation circuit to recover most of the silver and a small amount of gold, producing Ag-Au ingots. Following cyanidation, zinc flotation would be performed in a conventional rougher-scavenger-cleaner circuit to produce Zn-Ag concentrates. Residual materials would then be directed to a pyrite flotation circuit to reduce the bulk of residues with acid-generating potential in the tailings pond.
2008 optimization testwork
After Genivar's publication, several optimization tests and ore treatment scenarios were carried out. One scenario, identified as scenario B revision 2 and prepared in 2008, proposed recovering 80% of silver and 96% of zinc through a straight flotation process. This alternative process would produce a pyrite concentrate. The scenario indicated that the addition of a cyanidation circuit could recover 15% of the gold and 9% of the silver from the pyrite concentrate.
Existing site infrastructure
The report states that existing installations on site would be used if needed, including service building, warehouse, power line, fuel storage and refuelling station, roads, parking area, telephone line, artesian well, sewage treatment facilities, ditches and ponds. The service building would comprise engineering and mine department office, mine dry, mine warehouse, and a mechanical workshop for light vehicles and equipment of limited size, requiring only minor improvements and reshaping. The process plant would be erected on the foundations of the previous mill, and the repair shop for mining equipment would be constructed on an existing concrete slab near the service building.
Key reported parameters
| Parameter | Value | Basis |
|---|---|---|
| Proposed mill throughput | 1,800 t/day | 2007 Genivar design |
| Silver recovery (straight flotation) | 80% | 2008 scenario B revision 2 testwork |
| Zinc recovery (straight flotation) | 96% | 2008 scenario B revision 2 testwork |
| Gold recovery from pyrite concentrate (cyanidation addition) | 15% | 2008 scenario B revision 2 testwork |
| Silver recovery from pyrite concentrate (cyanidation addition) | 9% | 2008 scenario B revision 2 testwork |
| Historical production (open pit, 1952-1957) | 5,002,190 tonnes at 38.74 g/t Ag and 2.98% Zn | Actual operating data |
| Historical production (underground, 1986-1990) | 632,319 tonnes at 131.65 g/t Ag and 5.04% Zn | Actual operating data |
| Average gold grade from bulk samples | 0.138 g/t Au | Assay data from multiple laboratories |
Project website: https://www.abcourt.ca/projects/abcourt-barvue-property/
Technical qualifications
The report states that a new Feasibility Study is required for sections on recovery methods, project infrastructures, market studies and contracts, environmental studies and permitting, capital and operating costs, and economic analysis. The information on processing was mainly extracted from Genivar’s 2007 technical report and is delivered only to give the reader a first sight of the proposed methods. The report indicates that several optimization tests and ore treatment scenarios were carried out after Genivar's publication, but does not provide validation or detailed results. The design parameters presented are based on historical studies that require updating through a new Feasibility Study.
Source: Abcourt-Barvue Property , 2014 Resources Evaluation Report, Sections 17, 18, 24, 25
