The intracratonic Elk Point Basin is a major sedimentary geological feature in western Canada and the northwest U.S. It contains one of the world’s largest stratabound potash resources. The nature of this type of deposition is largely continuous with predictable depths and thickness. It is mined at several locations, including the Esterhazy Facility.

Potash at the Esterhazy Facility area occurs conformably within Middle Devonian-age sedimentary rocks and is found in total thicknesses ranging from approximately 100 to 131 feet (30 to 40 m) at a depth of approximately 5,345 to 5,740 feet (1,630 to 1,750 m).

The Prairie Evaporite Formation, host to the potash mineralization, is divided into a basal “lower salt” and an overlying unnamed unit containing three potash-bearing units and one unit containing thin marker beds. In ascending order, the potash horizons in the upper unit are the Esterhazy Member, White Bear Marker Beds, Belle Plaine Member, and Patience Lake Member. Mineralogically, these members consist of sylvite and halite, with minor amounts of carnallite (KCl, MgCl 6H O).

In the Esterhazy area, the Esterhazy, White Bear and Belle Plaine Members are present, and the Patience Lake Member is absent. The following is a summary of the key stratigraphic units for the Esterhazy Potash Facility area:
• Belle Plaine Member: The Belle Plaine Member underlies Second Red Bed and makes up part of the salt back that is critical to isolating the mining horizon from the formations above. The Belle Plaine Member is mined using solution mining techniques at the Belle Plaine Facility and is not mined at the Esterhazy Facility.
• White Bear Member: The White Bear Member consists of marker beds that are a distinctive unit of thin interbedded clay, halite, and sylvinite horizons that are not minable due to their insufficient thickness of only 4.0 to 5.0 feet.
• Esterhazy Member: The Esterhazy Member is separated from the Belle Plaine Member by the White Bear Member marker beds, a sequence of clay seams, low-grade sylvinite, and halite. The Esterhazy Member is mined using conventional underground techniques at the Esterhazy Facility in southeastern Saskatchewan, and by solution mining techniques at the Belle Plaine Facility.

The typical sylvinite intervals within the Prairie Evaporite Formation consist of a mass of interlocked sylvite crystals that range from pink to translucent and may be rimmed by greenish-grey clay or bright red iron insoluble material, with minor halite randomly disseminated throughout the mineralized zones. Local large one inch (2.5 cm) cubic translucent to cloudy halite crystals may be present within the sylvite groundmass, and overall, the sylvinite ranges from a dusky brownish red color (lower grade, 23% to 27% K O with an increase in the amount of insoluble material) to a bright, almost translucent pinkish orange color (high grade, 30%+ K O). Carnallite is also present locally in the Prairie Evaporite Formation as a mineral fraction of the depositional sequence. The intervening barren salt beds consist of brownish red, vitreous to translucent halite with minor sylvite and carnallite and increased insoluble materials content.

The Esterhazy Potash Facility, located in Saskatchewan, Canada started production at K1 in 1962 and at K2 in 1967. For approximately 60 years it consisted of two interconnected mines, K1 and K2. In 2010, work began to expand the mine into a new area of the potash deposit. The K3 mine is accessed with separate shafts and provides orc to the existing processing plants at KI and K2 via overland conveyor. Production at the K3 mine began in 2018 and is expected to operate until 2054. The KI and K2 mines ceased production in June 2021

K4, an area consisting of mineral resources has been scheduled in the 2021 LOM plan after mining depletion of the K3 mineral reserves. The mineral resources arc tentatively scheduled to start production in 2050 and expected to last until 2090. The processing plants at KI and K2 arc expected to be accessed via overland conveyors to receive the orc from K4.

Mining at Esterhazy has always used the room and pillar method. The planned total extraction of the in-situ potash ore is 27.6%. Pillars are left in place between mining rooms to support the overlying rock. This is intended to prevent a failure of the upper rock formations and to prevent an inflow of brine from any overlying water bearing zones. These pillars also help minimize localized rock movement and maintain safe working conditions for the underground work force.

The room and pillar mining is completed on a single level. The rooms are cut at 8.5 to 9.0 ft high (2.6 to 2.7 m) in the highest potash ore grade zone of the Esterhazy salt member.

Mine design work is completed utilizing the following design criteria:
- The three-entry development consists of 46.3 ft. (14.1 m) wide drifts, 300 ft. (91.4 m) wide pillars and a 9 ft. (2.7 m) mining height.
- The mainline conveyor standard length is approximately 6.000 ft. (1,829 m) but varies from 4,000 to 8,000 ft. (1,219 to 2.438 m) dependent on the panel layout.
- The room and pillar mine design consists of 66.5 ft (20.3 m) wide rooms with a height if 8.5 ft (2.6 m).
- The mining room nominal length is 6,000 ft. (1,829 m). The minimum length is 4.000 ft. (1,219 m), the maximum length is 9,000 ft. (2.743 m) and will vary in certain circumstances. Rooms shorter than 4,000 ft. (1,220 m) will result in excessive miner moves and setups that would adversely affect
miner productivity. If a mining room is longer than 9,000 fl. (2,743 m) the standard mining rate from the four-rotor miner will exceed the room conveyor capacity, thereby reducing the miner productivity by reducing the four rotor mining rate.
- A 1,000 ft. (305 m) barrier pillar is established between long term (greater than 10 year) mining entries and mining panel rooms.

A total continuous miner fleet of 13 four rotor miners with 11 to 12 miners setup to cut and one to two in maintenance/overhaul is assumed. There is a limit of one miner per single panel and a limit of two miners per double panel. Four rotor miners arc expected to have shutdowns for a six-month overhaul after cutting 12.0 M tons (13.2 M tonnes). Four rotor miners arc expected to have a minor overhaul shutdown for one month after cutting 6.0 M tons (6.6 M tonnes).

A four-rotor miners are cutting ore from stopes. After the ore mined in an active mining area, the ore is conveyed through a network of main line conveyors back to the shaft pillar area. The mainline belts dump into the underground bins. K3 has two ore bins and two surge bins. These bins allow ore to be stored underground, allowing mining to continue when the shaft is not available for hoisting.

All underground conveying systems discharge into the north and south raw ore bins. Ore is reclaimed from the bottom of the ore bins with rotating plow feeders that discharge onto a reclaim belt that transfers the ore to the surge bin. Ore is reclaimed from the bottom of the surge bin with apron feeders that discharge onto a shaft feed belt. Orc from the shaft feed belt is discharged into two weigh bins located in the shaft loading pocket. Theses bins then load the skips for transportation to surface.

Esterhazy K3 has two shafts in operation. The North shaft is equipped with two skips and a hoist to operate the skips. In addition, the north shaft has a four-compartment cage, operated by a hoist capable of load ups to 27 tons (24.5 tonnes), for the transportation of personnel and materials. The South shaft will be equipped with two skips and a hoist.

The skips discharge into a 300 ton (272 tonne) bin located in each headframe. Ore is reclaimed from these bins using apron feeders and loaded on the overland conveying system for transport to KI and K2 mills.

The crushing circuit processes raw ore supplied by the underground operations that contains Potash (potassium chloride. KCI). salt (sodium chloride. NaCl). and clays; within the circuit raw ore is reduced in size to less than 9.5 mm so that the potash and salt crystals are liberated for separation. Potash concentration in the ore feed stream is continuously read with an online ore analyzer. Raw ore is conveyed from the headframe bins to screen out on size and oversized ore. Oversize material is sent through a crusher so that it is reduced to the proper milling size, ore that is not reduced sufficiently recycles through the crushing loop until it is on size. On size material is slurried and sent into heavy media for further screening by size.

The Esterhazy Facility’s processing plant consists of two separate mill facilities, designated as K1 and K2. Each mill processes the raw ore feed stock received from the underground mining operations through crushing, separation, screening and compaction unit operations to produce ongrade, saleable product. The plants utilize online grade analyzers to monitor the process as well as routine samples that are analyzed by the onsite lab. The milling can be broken down into two main functions: the wet end separates potash and salt, while the dry end sizes potash for sale.

The wet end of the mill begins with raw ore sizing and crushing to prepare it for the separation processes. In heavy media, the larger size fraction is separated into potash and salt through dense media separation that is driven by differences of buoyancy in salt and potash. Flotation receives the smaller size fraction and has specific reagents added that allow the potash crystals to float while the salt is reje ........