The Jansen potash deposit is located within the Williston Basin, a large, intracratonic, structurally simple, and horizontally bedded sedimentary basin. The Williston Basin extends from southern Saskatchewan, Canada into the northern states of the United States of America.

Deposition of sediments in the basin began during the Cambrian geological time period, followed by an intense period of limestone, dolomite, evaporite, sandstone, and shale deposition during the geological time periods Ordovician, Silurian, and Devonian ending with Cretaceous sediments.

The potash beds are approximately 900 metres below surface at the top of the Prairie Evaporite Formation. There are three main potash bearing members present in the Prairie Evaporite Formation. Two are present in the Jansen area consistently, those being the Patience Lake and Belle Plaine members.

These potash members were deposited in regionally extensive (hundreds of kilometres), horizontal layers during the repeated, cyclical periods of evaporation of a shallow, inland sea during the Devonian Period. Mineralization within the potash layers consists of a layered, repetitive sequence of sylvite (KCl) with halite (NaCl) and thin layers of insoluble dolomitic clay material (clay seams). Carnallite (KCl.MgCl2.6H2O), a minera which can impact processing and ground stability, occasionally occurs in place of sylvite within the potash layer.

The Patience Lake member is further subdivided into Upper Patience Lake (UPL) and Lower Patience Lake (LPL) submembers. The LPL sub-member is the potash horizon targeted for Jansen.

Unconformably above the Prairie Evaporite is the Dawson Bay Formation that includes the Second Red Beds member and the Dawson Bay carbonate members on top.

Lower Patience Lake
The LPL sub-member is an approximately five metres thick potash unit interspersed with thin clay seams. The LPL top is marked by a thin, distinct clay seam (named the 406) that is overlain by an approximately 2.5 metres thick halite unit. The bottom of the LPL unit is marked by a disseminated clay seam (named the 401). The mineralization of the LPL is restricted to the 406 to 401 interval. The clay seams are consistent throughout the potash basin and the Jansen area and can be easily correlated between the drill holes. The LPL is subdivided into four mineralization cycles by BHP for detailed geological characterization of the potential mining horizon.

The deposit is relatively two-dimensional (laterally extensive and relatively thin) and is “soft rock” thus amenable to mining using track-mounted boring machines, roof-mounted or floor-mounted conveying systems, and ancillary rubbertired mining and transport equipment. The primary method of extraction is continuous mining using long room and pillar method within the Lower Patience Lake (LPL) sub-member. The LPL mining zone at Jansen ranges in depth below the surface from 840 metres in the north to 1,010 metres in the south.

The mine is designed to avoid the occurrence of water inflow from over lying aquifers through management of the extraction ratio, such that as time dependent creep of the pillars occur, the overlying strata withstands the mining induced stresses and remains intact. Production panel mining extraction ratio ranges between 41 per cent to 44 per cent and long term travelways have a reduced extraction ratio of 15 per cent for stress shielding.

Hydraulic conductivity measurements taken in drill holes and on core samples show that the carbonate members of the Dawson Bay Formation have low permeability or low inflow deliverability potential, but may pose potential risk of water inflow if hydraulically connected to vertically adjacent aquifers. The mine therefore treats the carbonates of the Dawson Bay Formation as having a high permeability as an inflow risk mitigation.

The pillar widths are based upon the study outcomes and recommendations, and guide the mine design, with depth and overburden type forming the calculation basis of the insitu stress for the Prairie Evaporite. Pillars within the mining horizon are used to enable safe mining of entries, maintain entry stability throughout their required life, and maintain the integrity of the overlying strata.

Mechanically-anchored rock bolts are the planned ground support method for the mine. The support pattern is based on overlying salt beam thickness and/or a change in material characteristics. When the overlying strata is thinner than the practical limit of rock bolt ground support, the strata will be excavated and become part of the processing stream as dilution. This dilution arising from mining overcut/undercut is combined with the dilution arising from orebody heterogeneity to generate diluted process plant ore feed.

Ground management in anomalous areas typically occurs in the form of ground support through rock bolts, cribbing, localized decreased extraction rate, and rarely with room abandonment.

The production mining rooms are excavated in two passes, yielding a 12 metres wide opening of varying length. Production pillar widths vary with deposit depth between 17 metres and 15 metres. Mining height is variable between 3.7 metres and 4.4 metres, with an average cutting height of 3.8 metres; the stability of strata overlying the 406 clay seam drives cut heights greater than the targeted mineralised zone. With the exception of the shaft pillar area, all excavations are expected to occur in the LPL. Ore losses between mining face and the ore processing plant have not been considered.

Borer miners and accompanying Extendable Belt System (EBS) make up the selected mining system for continuous mining in production rooms. A network of conveyor belts transport the ore from the working face to the shaft area for hoisting at the Service shaft. Production mining is supported by a fleet of continuous mining machines, battery haulers, Load Haul Dump units, maintenance vehicles, and personnel carriers.

Underground excavation of the shaft pillar and district development will be completed during mine development. The shaft pillar contains infrastructure including mine facilities, mine utilities, ventilation infrastructure, and the bulk material handling system.

The mine conveyor network is designed to transport ore from each mining face to the shaft pillar. The shaft pillar contains a series of conveyors and storage or buffers prior to flask loading, where the ore is hoisted to surface for processing. The three main conveyor system configurations are panel, block and mainline conveyors.

The mine will begin initial production following the construction of the main bulk material handling facilities to enable ore flow through the main ore storage bin, surge bin, service shaft loadout, and service shaft hoisting systems. Following the completion of performance testing of the first borer/EBS mining system the operation will move forward to full capacity. Handover to Operations will occur at designated boundaries in the east and north districts.

Conveyors will transport ore from the Service shaft to the processing plant or the raw ore stage building. The ore will then be crushed and screened before being fed to the wet scrubbing circuit, where it will mix with brine in the pulping tank. Salts (which contain the potash) will be separated from the insoluble material, then pumped to a flotation circuit to form a potash concentrate. The concentrate is then transferred to a centrifuge to remove the brine to form a concentrate cake. The fine salts are then mixed with reagents. The processing circuit will produce two types of saleable potash; a standard-sized and granular sized product. From the processing plant, the saleable potash will be loaded on to potash railcars and hauled to Westshore Terminals in Delta, British Columbia.

The process design of the plant is based on three principal processing considerations:
• K: Target mineral recovery;
• Mg: Potential negative effect on flotation recovery;
• Insolub ........