The June 2013 IDP report details two processing routes based on crushing, radiometric ore sorting, milling, ablation, two-stage tank leaching, and either RIP-SX or enhanced Cyanex 600 solvent extraction for uranium recovery.
Report context
The June 13, 2013 integrated development plan (IDP) for the Madaouela project in Niger presents updated processing designs developed after further metallurgical testwork, mainly by SGS and Mintek, following a 2010 preliminary economic assessment. Tenova Bateman was appointed to develop designs, capital and operating costs to a prefeasibility study level for three alternative treatment flowsheets. The IDP base case process option, defined by economics, was radiometric ore sorting, acid leach and resin-in-pulp/ion exchange to produce yellowcake. Further testwork completed after the June 2013 IDP, including ablation, Cyanex 600, and nanofiltration, led to the selected flowsheets presented in this updated IDP report.
Processing route
Flowsheet Options
Two flowsheets are presented: Option 1A (Crushing, ROS, Milling, Ablation, two stage leach and RIP-SX) and Option 1B (Crushing, ROS, Milling, Ablation, two stage leach and Cyanex 600 SX). Option 1B is the base case.
Ore Receipt and Feed Preparation
Mined ore from Marianne and Marilyn is crushed underground (80% < 306 mm) prior to transport and received on surface. Feed preparation consists of two-stage crushing with intermediate screening. Ore from the stockpile is reclaimed by three apron feeders and routed to a secondary jaw crusher operating in open circuit, with product screened and oversize routed to a tertiary cone crusher with product returned to the sizing screen. Product from the crushing circuit is nominally < 20 mm (80% passing).
Radiometric Ore Sorting
Primary crushed ore is routed to radiometric ore sorting (ROS) where fines are screened out and routed directly to fine crushing, with the coarse fractions (+20 mm) subject to preconcentration. The accept product only is routed to fine crushing while rejects go to a waste stockpile. Two ROS circuits are specified for sorting size ranges of 20-90 mm and 90-300 mm. ROS recovery is 98.5% with a yield of 55%, and uranium loss in ROS rejects is 8-10%.
Ablation
Accept product from ROS is secondary crushed and mixed with water to create 20% slurry, fed into the ablation stage where jets of slurry create a high energy impact zone causing breakdown of ore into coarse and fine particles separated by screening and gravity. Uranium is predominantly in the fine particles; this fine material slurry is thickened prior to feeding into acid leach tanks. Coarse material is thickened and sent to tailings. An additional recovery step involves gravity separation of residual uranium from the coarse material fed back into the ablation product, improving overall recovery to 99%. Ablation mass pull to leach is 36%, with ablation product size 149 microns (150% passing) and uranium loss in ablation rejects of 7%. Ablation recovery is 93.0%.
Two-Stage Tank Leaching
The two-stage leaching circuit consists of primary and secondary agitated leach tanks in recirculation with a leach thickener after the first stage and a belt filter after the second stage leach. In the first stage, solution from the second stage belt filters is recirculated to leach fresh feed, after which slurry is thickened with overflow routed to uranium recovery as pregnant leach solution. Thickener underflow goes to second stage leach using fresh acid. After the second stage, slurry is filtered and washed solids residue discarded to tailings. Leach tanks are agitated and aerated to allow milled ore to react with sulfuric acid. Leach recovery is 92.0%.
Uranium Recovery – Option 1A (RIP-SX)
For the RIP-SX option, pregnant leach solution undergoes adjustment to pH 3.5 using milk of lime to selectively precipitate impurities including molybdenum. Uranium recovery takes place through ion-exchange onto resin in six IX stages. This is followed by elution of uranium from recovered resin to produce concentrated eluate forwarded to solvent extraction. In the SX circuit, uranium is extracted from the IX eluate into an organic phase consisting of Alamine 336 in kerosene using three countercurrent extract mixer-settlers. The loaded organic solvent is stripped in four stages with sodium carbonate to produce uranium rich liquor for sodium diuranate precipitation. SDU precipitate is thickened, filtered, re-dissolved with sulfuric acid, and further purified in a fluid-bed precipitation unit with peroxide and caustic addition, followed by filtration, drying and drum packaging of yellowcake.
Uranium Recovery – Option 1B (Cyanex 600 Enhanced SX)
The enhanced SX process uses CYANEX 600, a highly selective phosphinic acid based reagent, to recover both molybdenum and uranium from acidic solutions. The circuit consists of two extraction steps, one iron stripping step, two molybdenum stripping steps, an ammonia wash, and two uranium stripping steps. Molybdenum oxide is precipitated by conversion of tetramolybdate. Recovery for the enhanced SX option is 99.0%.
Acid Plant
Acid for the process is supplied by a dedicated onsite acid plant from burning of sulfur, with a capacity of 400 tpd, incorporating double conversion/double adsorption technology, steam and power generation from waste heat, and acid storage and distribution.
Key reported parameters
| Parameter | Unit | Option 1A (RIP-SX) | Option 1B (Enhanced SX) | Basis |
|---|---|---|---|---|
| Total Feed | tpd | 4,020 | 4,020 | Design |
| U Head Grade | ppm | 1,000 | 1,000 | Design |
| Total U Feed | kg/hr | 142 | 142 | Design |
| U Product | kg/hr | 116 | 116 | Design |
| U Product | lb/a | 2,242,938 | 2,242,938 | Design |
| ROS Recovery | % | 98.5 | 98.5 | Testwork |
| Ablation Recovery | % | 93.0 | 93.0 | Testwork |
| Leach Recovery | % | 92.0 | 92.0 | Testwork |
| Recovery SX | % | 99.0 | 99.0 | Testwork |
| Overall U Recovery | % | 83 | 83 | Design |
| Plant Overall Design Availability | % | 86 | 86 | Design |
| Feed size from mining (80% passing) | mm | 250 | 250 | Design |
| Feed size after crushing (80% passing) | mm | 20 | 20 | Design |
| Mill product size (80% passing) | micron | 500 | 500 | Design |
| Acid Consumptions in Leach | kg/t ore | 100 | 100 | Testwork |
| PLS Flow to Uranium recovery | m³/h | 50 (approx.) | 50 (approx.) | Design |
| Solution Tenor Uranium | g/l | 2.5 | 2.5 | Testwork |
| Solution Tenor Molybdenum | mg/l | 800 (approx.) | 800 (approx.) | Testwork |
| Lime addition | kg/t ore | 0-5.5 | 0-5.5 | Design |
| Acid Plant Capacity | tpd | 400 | 400 | Design |
| Water consumption | m³/t feed | 2.3 | 2.3 | Design |
Project website: https://www.juniorminingnetwork.com/junior-miner-news/press-releases/423-tsx-venture/gxu/16073-mining-permit-approved-for-goviex-s-madaouela-project.html
Technical qualifications
The testwork samples were sourced from stockpiles adjacent to the Marianne and Marilyn deposits mined in the 1960s. It is suspected that samples had partially deteriorated physically both on stockpiles and in transport with generation of fines noted, although extensive mineralogical characterization indicated limited oxidation. Concerns were highlighted regarding ROS testwork representativeness due to physically weathered samples with significant fines generation removed prior to sorting. Leach testwork on ROS accept product resulted in higher acid consumption compared to treating whole ore feed, suspected to be caused by higher carbonates in fines that bypassed ROS sorting.
The Tenova Bateman forecast accuracy for both operating and capital costs is -15% to +40% with a probability of not more than 50% and has not included a contingency allowance on operating costs. For mechanical equipment, only around 10% of costs were based on quotes, with the remaining 90% based on factored costs (80%), database numbers and allowances. The ROS package costs were based on limited information from equipment manufacturers in Ukraine and Germany, with detailed costs and scope not provided. Areas were highlighted where due to time constraints and changes to proposed flowsheet options and throughputs, the costing philosophy was not adhered to and costs were scaled from investigations on different plant capacities. The general arrangement drawings have not been updated for current revised throughputs.
The capital estimate excludes owners costs, land acquisitions, exploration costs, geotechnical studies, taxes, import duties, project finance costs, escalation from capital estimate base (April 2013) to project completion, client management and overall project contingency, supply of water and power during construction, and site security.
Source: U4877_Madaoulela_IDP_V54.docx September 2013, Recovery Methods section.
