The processing of uranium is driven by the host mineralogy. There are a range of different uranium host minerals, each with different processing requirements. This leads to a wide variety of process circuit options. The major uranium host minerals are oxides, meaning that processing circuits are generally focused on hydrometallurgy. Gangue mineralogy also plays an important role in uranium processing, often driving process selection decisions.
Uranium processing falls into 3 categories:
- In-situ processing
- Acid leaching
- Alkaline leaching
In-situ leaching is the most prevalent process, dominating uranium production in Kazakhstan, the world’s largest producer. This is a low cost option but requires the right geological conditions and mineralogical composition to be implemented.
The next most important technology is acid leaching, comprising most of the production in Canada and Australia. The configuration of acid leaching circuits is driven by mineralogy, with more refractory minerals, such as brannerite requiring more intense conditions and addition of oxidants than readily leached minerals, such as uraninite.
In addition to complex process flow sheets uranium projects must comply with additional radiation management and security requirements to other commodities. These processes are well established by the International Atomic Energy Association (IAEA) but do require additional consideration when developing a new project.
MinAssist brings experience across project development for uranium resources. Our strong focus on understanding the distribution of uranium with host minerals allows us to develop robust process flow sheets that maximise capital efficiency and minimise operating costs. The uranium market has been challenging since the 2011 Fukushima disaster and successful development of any new projects requires practical and innovative thinking.
In addition, MinAssist has experience along all stages of the uranium development process, including working with IAEA and regulators to ensure that solutions follow global best practice and comply with all international guidelines.
Finally, alkaline leaching is required for uranium resources high in carbonate minerals, principally carnotite. Only a small fraction of uranium is produced by alkaline leaching, with the best example being Paladin’s Langer Heinrich Mine in Namibia.
- Sampling audits
- Geometallurgical modelling of uranium resources
- Mine to mill studies
- Operational mineralogy
- Circuit auditing and optimisation
- By product optimisation
- Process flow sheet development
- Process simulation
- JORC competent person – metallurgy for acid and alkaline uranium flow sheets
MinAssist has completed a number of significant uranium projects:
Uranium in the Haggan Resource occurs at very low grade (~140ppm U average), hosted in a Black Shale matrix.
The host material is high in calcite, an acid consuming mineral, and pyrite, a carbonate consuming mineral, making both conventional acid tank leaching and alkaline leaching uneconomic.
MinAssist undertook extensive mineralogical characterisation, determining the deportment and grain size of both the uranium host matrix and gangue minerals.
Based on the mineralogy a conceptual flow sheet was developed utilising a bacterial heap leach. This process generated its own sulphuric acid reagent through bacterial oxidation of pyrite, more than counteracting the acid consuming effects of calcite. This innovative flow sheet was assessed as part of Aura Energy’s Haggan uranium scoping study, resulting in an NPV of US1.7 Billion.
MinAssist developed and tested an innovative alkaline uranium leach flow sheet for Aura Energy’s Tiris uranium project, Mauritania.
Uranium in the Tiris resource occurs in fine grained carnotite. Using detailed mineralogical characterisation MinAssist determined that using a simple scrubbing and screening process up to 90% of the mass could be rejected, while retaining over 90% of the uranium in the leach feed. This allowed development of an efficient process flowsheet where only 10% of the feed ore mass was processed through the leaching circuit, resulting in significant Capital and Operating expenditure savings.
MinAssist assisted Aura Energy through the development process, driving both preparation of the Scoping Study and Definitive Feasibility Study, published in July 2019. This DFS results indicated a target production of 1Mlbs U3O8 per annum with NPV8 of $**M. Importantly this required only moderate capital expenditure of $**M and a breakeven uranium price of $** /lb U3O8.
How can we help you?
- Geometallurgical model development
- Mine to mill studies
- Copper flotation circuit audits
- Copper by-product characterisation and circuit optimisation