The Lalor VMS deposit is flat lying, with zinc mineralization beginning at approximately 570m from surface and extending to a depth of approximately 1,160m. The mineralization trends about 270° to 310° azimuth and dips between 15° and 30° to the north. It has a lateral extent of about 900m in the north-south direction and 700m in the east-west direction.

Sulphide mineralization is pyrite and sphalerite. In the near solid (semi-massive) to solid (massive) sulphide sections, pyrite occurs as fine to coarse grained crystals ranging one to six millimetres and averages two to three millimetres in size. Sphalerite occurs interstitial to the pyrite. A crude bedding or lamination is locally discernable between these two sulphide minerals. Near solid coarse grained sphalerite zones occur locally as bands or boudins that strongly suggest that remobilization took place during metamorphism.

Disseminated blebs and stringers of pyrrhotite and chalcopyrite occur locally within the massive sulphides, adjacent to and generally in the footwall of the massive sulphides. The hydrothermally altered rocks in the footwall commonly contain some very low concentrations of sulphide minerals.

Some sections of massive pyrrhotite occur, but these tend to give way to pyritesphalerite-dominant zones.

Gold and silver enriched zones occur near the margins of the zinc rich sulphide lenses and as lenses in local silicified alteration. Remobilization is illustrated in some of the goldrich zones by late veining that is more or less restricted to the massive lenses. Some of the footwall zones tend to be associated with silicification and the presence of gahnite. These zones are often characterized by copper-gold association, and are currently interpreted as being associated with higher temperature fluids below a zone of lower temperature basemetal accumulations.

Footwall gold mineralization is typical of any VMS footwall feeder zone with copper-rich, disseminated and vein style are overlain by a massive, zinc-rich lens. The fact that the footwall zone is strongly enriched in gold suggests a copper-gold association which is comparable to other gold enriched VMS camps and deposits (Mercier-Langevin, 2009).

General observations of the known gold zones indicate areas which are coarse grained and porphyroblastic in nature are gold poor, while fine grain siliceous (± veins ± sulphide traces) and strained looking stratigraphy tend to be gold rich. To date no definitive structural controls of the gold mineralization has been interpreted. However, the intensity and style of alteration can vary strongly over short distances and may suggest that the alteration was forming discordant stockwork like zones that are now strongly transposed in the main foliation (Mercier-Langevin, 2009).

The Lalor mine is a multi-lens flat lying orebody with ramp access from surface and shaft access to the 955 m level. Internal ramps located in the footwall of the orebody provide access between mining levels. Stopes are accessed by cross cuts from the major mining levels.

The mining method process includes underground lateral advance (development rounds), production mining, backfilling and transporting ore to surface. Geotechnical information, orebody geometry interpreted from diamond drill core and recent experience mining within the deposit were the major considerations for selection of mining methods.

Mining methods that are currently in use or planned in the immediate future include: mechanized cut and fill, post pillar cut and fill, drift and fill and longhole open stoping (transverse and longitudinal retreat).

Ore is mucked using Load Haul and Dump (LHD) loaders which are operated remotely in inaccessible areas. The ore is then loaded into underground haul trucks or ore passes and transported to the ore handling system at the production shaft for hoisting to surface.

A paste backfill plant will be constructed on site, planned for the first quarter of 2018. Paste backfill will be used in higher grade areas to increase recovery and accelerate the mining cycle. Lower grade areas will be filled with waste rock from waste development. No waste is planned to be hoisted.

Ore delivered to the production shaft is sized to less than 0.55 m at one of the two rockbreaker/grizzly arrangements and hoisted from the mine by two 16 tonne capacity bottom dump skips in balance. Ore is truck hauled to a primary crusher at the Chisel North mine site, crushed to less than 0.15 m, and then trucked to the Stall concentrator for further processing.

The orebody is polymetallic with economically significant metals being zinc, gold, copper and silver. There are two different ore type, both of which are assumed to be treated using conventional flotation at Hudbay Stall concentrator:

- Base metals ores. Near solid to solid sulphide ores, with dominant pyrite and sphalerite with minor blebs and stringers of chalcopyrite and pyrrhotite.
- Gold rich ores. Silicified gold and silver enriched ores with stringers to disseminated chalcopyrite and sphalerite mineralization.

The Stall concentrator complex is located approximately 16 km east of the Lalor mine. Conventional crushing, grinding and flotation operations are used to process the ore. The nominal throughput rate will be expanded from the current 3,000 tpd rate to 4,500 tpd and the mill will operate 24 hours per day, 365 days per year, with scheduled downtime for maintenance as required.

The concentrator produces a copper concentrate with gold and silver credits and a zinc concentrate, both are shipped by truck to Flin Flon, from there the copper concentrate is loaded onto rail cars and shipped to third party smelters. Tailings from the flotation circuit will be utilized to produce a cemented paste backfill for use underground at Lalor. Tailings not required for paste backfill will continue to be pumped to the existing Anderson TIA.

Run of mine ore as large as 0.55 m in one dimension is withdrawn from the head frame ore bin at Lalor and is transported to a crushing plant located at the Chisel North mine. The crushing plant reduces the ore to a range of 10 to 15 cm and is transported to the Stall concentrator coarse ore bins or to a stockpile at the mill. A stockpile of 36,000 tonnes, equivalent to 8 days production at the future expansion rate, is required to blend high-grade zinc to ensure a more consistent zinc feed.

The Stall concentrator consists of the following areas: stockpiles, crushing and screening, grinding circuits, copper and zinc flotation process, and concentrate dewatering. Flotation tailings currently pumped to the Anderson TIA will be pumped to the future paste plant at Lalor or to the Anderson TIA depending on the demand for paste. Water for the ore-grade mineral extraction process utilizes two sources: fresh and reclaimed water. Approximately 25% of the water usage is withdrawn from the fresh water of Snow Lake while the remaining approximately 75% of the water is reclaimed from Anderson TIA.

Engineering for the Stall concentrator expansion is currently underway and construction is planned to commence in the third quarter of 2017 with commissioning in the third quarter of 2018. This schedule is offset to the Lalor production ramp-up by about 6 months. Lalor is planned to be at a nominal mining rate of 4,500 tpd in the first quarter of 2018. The additional ore tonnage from Lalor is planned for either stockpiling or will be transported to the Flin Flon concentrator for processing.