Boss Resources has announced plans to evaluate the replacement of the existing solvent extraction (SX) columns on the Honeymoon uranium mine site, in South Australia, with new NIMCIX columns.

Initial results from test work indicate the potential for this to increase production profile and reduce operating costs for the project, Boss said.

The NIMCIX contactor is a continuous ion exchange (IX) column developed by Mintek (then the National Institute for Metallurgy – NIM) during the uranium boom of the 1970s and 1980s. A notable breakthrough, it enabled uranium to be recovered from unclarified solutions, according to Mintek.

Following a January 2020 feasibility study on Honeymoon, the company has embarked on technical optimisation studies which included completing NIMCIX IX process detail design and testing. In August, cost saving results from a GR Engineering review relating to reduced site power demand and transmission line upgrade costs were announced.

These savings, along with the NIMCIX results have incentivised Boss to initiate an Enhanced Feasibility Study (EFS) to incorporate the potentially significant enhancements identified, it said.

Boss’s restart and expansion plans have been split into separate stages, of which Stage 1 and 2 are presented as the base case for the Honeymoon feasibility study, showing that production can recommence within a 12-month period. Stage 1 development focused on the restart of the existing SX plant, which has a nameplate capacity of 880,000 lb/y U3O8-equivalent. Stage 2 is an expansion strategy that will increase production to 2 Mlb/y U3O8-equivalent and involves the construction of a new IX circuit.

Additional work has now been completed by Boss, ANSTO and GR Engineering examining the potential to replace the existing SX columns on site with new NIMCIX columns.

Boss said: “The results show that it is entirely possible to eliminate the envisaged Stage 1 and incorporate a NIMCIX system with the following stipulations:

• “The flow rate through the new NIMCIX columns must be equivalent to or higher than the SX system;
• “The lead time to commissioning should not be significantly impacted;
• “The overall project capital expenditure intensity should not be impacted; and
• “As much of the current SX structural and process infrastructure as possible to be re-used.”

The conclusion of this review is that these criteria are achievable and highlighted the potential for lower unit operating cost and higher production rates over the life of mine, according to Boss.

Additional potential benefits of the conversion include:

• Significantly higher throughput through the plant during Stage 1 and beyond;
• Improved safety outcomes through the elimination of combustible solvents in process;
• Improved environmental outcomes through elimination of the potential for organic entrainment to the wellfield; and
• Simplification of the process through standardisation of uranium extraction technology.

“The company now plans to incorporate both the IX Process Optimisations announced previously and the pure NIMCIX adoption into an EFS level estimate for the Honeymoon uranium project restart to assess the economic impacts of these changes,” it said.

It has re-engaged GR Engineering Services as the engineering and lead study consultant for its EFS leveraging on the recently completed feasibility study completed in January 2020.

“Through the EFS, Boss aspires to increase the ramp up production schedule and nameplate capacity of Honeymoon through the adoption of a wholly IX (NIMCIX) system with the first stage of production ramp up delivered within the original 12-month delivery timeline from an investment decision,” it said.