Wynyard Carnallite Project — 2012 Recovery Methods

This section describes the proposed processing methods for potash and magnesium products recovery at the Wynyard Carnallite Project, based on a prefeasibility study completed in 2012.

Report context

The recovery methods presented in this article are drawn from Section 17 of the amended and restated Technical Report titled "KCl and MgCl2 Reserve and Resource Estimate for the Wynyard Carnallite Project, Subsurface Mineral Permit KP 360A and Subsurface Mineral Lease KLSA 010, Saskatchewan, Canada," dated 27 June 2012. The report was prepared on behalf of Karnalyte Resources Inc. for the Magnesium Products Prefeasibility Study. The recovery methods section outlines the proposed processing route for potash production and describes the magnesium products recovery method, supported by testwork data from dissolution, evaporation, crystallization, and milling test programs.

Processing route

Potash Processing Plant Design

The Potash Processing Plant design is based on a production capacity of approximately 630,000 tonnes per year of KCl. The processing plant is designed to treat brine produced from solution mining of the Patience Lake, Belle Plaine, and Esterhazy members. The plant incorporates a conventional crystallization circuit for KCl recovery. The processing route was developed from testwork including dissolution testwork, evaporation and crystallization test work, and milling and grinding tests.

Insolubles Removal

The processing flowsheet includes an insolubles removal stage as the first step in brine treatment. The brine from solution mining is expected to contain insoluble materials that must be removed prior to evaporation and crystallization. The design basis for insolubles removal is drawn from industry standard practice for potash processing operations in Saskatchewan.

Evaporation and Crystallization

The evaporation and crystallization circuit is designed to concentrate the brine and selectively crystallize KCl. The process is based on the solubility characteristics of the carnalitic brine system. Evaporation is performed using mechanical vapour recompression evaporators. Crystallization is controlled to produce KCl product crystals of specified size and purity. The design of this section incorporates results from dedicated evaporation and crystallization test work that was completed as part of the metallurgical testing program.

Sodium Chloride and Potassium Chloride Debrining

After crystallization, the KCl crystals are separated from the mother liquor and subjected to debrining to remove residual brine. Sodium chloride debrining is also incorporated in the flowsheet to manage salt content in the process stream. The debrining step uses centrifuges and washing stages to achieve product purity specifications.

Drying and Formulation

The debrined KCl crystals are dried in rotary dryers to produce a finished product with a moisture content suitable for storage and handling. The formulation stage includes screening and compaction equipment to produce granular product as required by the market. The design incorporates standard potash drying and formulation technology.

Product Storage and Load-out

The finished KCl product is conveyed to product storage facilities with capacity for seasonal production and shipping schedules. Load-out facilities are designed for rail and truck transport.

Magnesium Products Recovery Method

The Magnesium Products recovery method is described as a separate processing route. Two process options are identified in the report. The first option is a Magnesium Chloride Brine Process that produces a concentrated magnesium chloride brine product. The second option is a Hydromagnesite Process that produces hydromagnesite (magnesium carbonate) as the final product.

Magnesium Chloride Brine Process

The Magnesium Chloride Brine Process is designed to process the magnesium-rich brine that remains as a by-product stream from the potash recovery circuit. The process involves further evaporation and purification steps to produce a concentrated magnesium chloride brine product. The mass balance for this process was developed by the qualified person responsible for the Magnesium Products Prefeasibility Study beginning in August 2011.

Hydromagnesite Process

The Hydromagnesite Process uses the magnesium chloride brine as feed and precipitates hydromagnesite through a carbonation reaction. The process is described as producing a solid magnesium carbonate product. The report notes that testwork results were used to support the development of the mass balance for this process option.

Key reported parameters

Technical qualifications

The recovery methods section of the report is based on a prefeasibility study level of design. The processing plant design has not been finalized with detailed engineering; the report notes that the flow sheet and mass balance were reviewed and updated several times between August 2011 and the report date. The design assumptions rely on testwork results from dissolution, evaporation, crystallization, and milling test programs. The report does not include detailed equipment specifications, operating performance data, or operational history for the proposed plant, as the project has not proceeded to construction or operation. The recovery methods are presented as conceptual designs that would require additional testwork and engineering for final process definition. No pilot plant or commercial operating data from the Wynyard Carnallite Project were available at the time of the report.

Source: Section 17 of the Technical Report "KCl and MgCl2 Reserve and Resource Estimate for the Wynyard Carnallite Project, Subsurface Mineral Permit KP 360A and Subsurface Mineral Lease KLSA 010, Saskatchewan, Canada," dated 27 June 2012. Recovery Methods sections 17.1–17.3.