This review of the 2012 Pre-Feasibility Study technical report summarizes the planned design of the Lalor concentrator, a new facility at the Snow Lake, Manitoba site, focusing on the conventional crushing, grinding, and flotation process.
The 2012 Pre-Feasibility Study for the Lalor Deposit details the design of a new concentrator complex to be located at the existing project site in Snow Lake, Manitoba. The facility is designed for a nominal throughput of 4,500 tonnes per day, operating 24 hours a day, 365 days a year, with scheduled downtime for maintenance. The processing plant is intended to produce a bulk copper-lead concentrate with gold and silver credits and a zinc concentrate, both for shipment by truck to Flin Flon.
Ore processing will use conventional crushing, grinding, and flotation methods. Coarse ore, as large as 610 mm in one dimension, will be withdrawn from the head frame ore bin and fed to a jaw crusher. The crushed discharge at minus 150 mm will be conveyed to an enclosed stockpile with a maximum capacity of 10,000 tonnes and a live capacity of approximately 2,000 tonnes. From the stockpile, ore is fed to a Semi Autogenous Grinding (SAG) mill operating in a closed circuit with a vibrating screen. The SAG mill discharge undersize is processed through primary cyclones, with the overflow, at a target P80 of 80 microns, flowing to the flotation circuit. Cyclone underflow is directed to a ball mill also operating in closed circuit with the cyclones.
A portion of the cyclone underflow is diverted to a flash flotation cell to recover liberated gold and copper, with the concentrate sent to a regrind circuit. The flotation feed is conditioned with reagents before entering a bulk copper-lead rougher/scavenger flotation circuit comprised of six tank cells in series. The rougher concentrate, along with the flash flotation concentrate, is reground to a target P80 of 30 microns. The reground bulk concentrate is cleaned in a closed three-stage tank cell flotation circuit. Tailings from the flotation circuit will be used to produce cemented paste backfill for the underground mine, with excess pumped to the existing Anderson Tailings Impoundment Area.
Critical Data
| Parameter | Value | Unit | Notes |
|---|---|---|---|
| Nominal throughput | 4,500 | tpd | Not stated |
| Coarse ore maximum size | 610 | mm | In one dimension |
| Crusher discharge top size | 150 | mm | Minus 150 mm |
| Stockpile maximum capacity | 10,000 | tonnes | Enclosed to minimize dust |
| Stockpile live capacity | 2,000 | tonnes | Approximately |
| Primary cyclone overflow target P80 | 80 | microns | Flotation feed |
| Regrind mill target P80 | 30 | microns | For bulk concentrate |
| Estimated water consumption | 2,768,000 | m³/yr | Total for the concentrator |
| Estimated fresh water consumption | 344,000 | m³/yr | 12.4% of total |
| Estimated reclaim water consumption | 2,424,000 | m³/yr | 87.6% of total from thickener overflows, TIA, and mine water |
| Estimated water consumption total | 1.69 | m³/tonne | Based on nominal throughput |
| Fresh water pipeline length | 13.3 | km | 150mm insulated polyethylene |
| Reclaim water pipeline length | 16.2 | km | 200mm insulated polyethylene |
| Fresh water pumps max flow | 91 | m³/h | Existing pumps to be replaced with larger units |
| Reclaim water pumps max flow | 233 | m³/h | Existing pumps to be replaced with larger units |
| Filter feed tank storage | 6 | hours | For paste backfill feed |
| Process water tank sources | Not stated | Not stated | Mine water first, then reclaim water |
Project website: https://gov.mb.ca/iem/geo/gis/activity/hudbay_minerals_inclalor_lake_deposit.html
Overview
The planned Lalor concentrator is designed as a conventional flotation plant with a nominal capacity of 4,500 tonnes per day. The process flowsheet incorporates a jaw crusher, a SAG mill, a ball mill, and a regrind mill for size reduction. Flotation is conducted in tank cells for bulk copper-lead and zinc recovery. The process water system is designed for high recirculation, sourcing from mine water and reclaim systems to minimize fresh water consumption.
Key Process Stages
Run-of-mine ore from the head frame bin is crushed in a jaw crusher before being conveyed to a crushed ore stockpile. Grinding is achieved in a SAG mill and ball mill circuit. A flash flotation cell is included to recover fine liberated gold and copper from the ball mill cyclone underflow. Flotation feed is conditioned with reagents and processed in a bulk copper-lead rougher/scavenger circuit followed by a three-stage cleaning circuit. Regrinding of the rougher concentrate to a P80 of 30 microns occurs before cleaning. The final concentrate is dewatered, and tailings are thickened for use as paste backfill or for deposition in the Anderson Tailings Impoundment Area.
Additional Interesting Data and Summary
The technical report states that flash flotation was not tested in the laboratory but was included in the flowsheet based on successful experience in the Flin Flon Concentrator for recovering fine gold. A significant portion of the water used in the process, approximately 87.6 percent, comes from reclaimed or mine sources. The paste backfill system includes a filter feed tank with six hours of storage capacity. The tailings pumping system will have a leak detection system installed along its full length. A small amount of fresh water will be required for applications where process water is not acceptable.
Key Processes
- Crushing
- Semi Autogenous Grinding (SAG) and ball milling
- Flash flotation for gold and copper recovery
- Bulk copper-lead and zinc flotation
- Regrinding
- Dewatering and paste backfill production
Source: Lalor Deposit , 2012 Pre-Feasibility Study Technical Report, 2012.
Project website: Lalor Deposit, 2012 Pre-Feasibility Study Technical Report
