Refinement is the process that mined material undergoes so as to remove all undesirable minerals and separate the desired elements. Because the global issues concerning platinum group elements, radioactive minerals, rare metals, lithium and phosphorus result primarily from a lack of distribution as opposed to a lack of production efficiency, Mission 2016 did not work to improve recovery methods of these resources. However, because the most common methods of refining REEs are inefficient, costly, and complex, improvements to these processes are vital to increase in the global supply of REEs. The current average recovery rate in the industry is 50-60% ("The world's largest rare earth mine..."), resulting in a current global supply 113 kilotons of REEs (Hatch 2012). Mission 2016's solution aims to raise this recovery rate to 75%, resulting in an increase of approximately 36% in yearly supply.
For elements like lithium, uranium, phosphorus, rare metals and PGE the refining techniques are less of an issue versus political, social, recycling rates and substitution/reduction in use, and Mission 2016 did not work improve these techniques.
The rare earth refinement process typically yields only a small percentage of the desirable elements contained in the ore, a percentage referred to as "recovery rate". Maximizing the recovery rate of rare earth elements through development and perfection of the refinement processes is vital to the increased capacity of production of rare earth elements (REEs). The most significant factors to consider when analyzing the benefit of refinement methods are recovery rate, financial cost, environmental impact and speed of the process.
This plan primarily consists of increased implementation of newly developed technologies, integration of different methods, and regulation of current refineries. The plan addressing this necessity makes great use of scientific discoveries already made but not yet in widespread use. These developments are detailed below.
Recent Improvements of Refinement Methods
Improvement of the Traditional Method: Molycorp
The traditional method of extracting pure REEs from mined material is called the solvent-exchange method, and consists of first crushing the rock into smaller chunks and then grinding it into a fine dust. Unwanted materials (largely iron oxide minerals and carbonate minerals) are removed using various separation methods, leaving behind an ore of REEs and radioactive material, which are then separated using additional means of chemical leaching (Kidela 2011).
This method requires copious amounts of chemicals which result in excessive chemical waste (including radioactive sludge) which is both expensive and environmentally harmful. However, Molycorp has managed to make use of the standard solvent exchange method of purification without suffering the common downsides of this process by correcting for environmental damages and inefficiencies in the planning of their refineries. One process that required large amounts of ammonia and resulted in pollution of lakes and rivers with ammonia-infused water was significantly improved by Molycorp's water-recycling developments. This process is called saponification and it removes unwanted minerals using the chemical separation of ammonia from the material (Feng 2012). Molycorp engineers devised a process for reclaiming the ammonia from the ammonium-infused water waste for reuse in future saponification (Smith 2012). This technology increased their efficiency by reducing the amount of ammonia needed for refinement and it eliminated the ammonia-water byproduct that leaked into the surrounding environment. Additionally, Molycorp stores their radioactive waste in contained paste tailings facilities in a solid state as opposed to allowing it to seep into the surrounding ecosystem as radioactive sludge (Davis 2012).
These developments have decreased the cost of the refinement process as well as the negative environmental impact. Molycorp's major project, Mountain Pass, has projected an unprecedented recovery rate of 90% due to numerous repetitions of separation reactions as well as anti-waste precautions born from experience with the particular grade of Mountain Pass (Schuler). Although such a high recovery rate cannot be expected of all refineries (most mining businesses lack the financial means of Molycorp), a portion of Molycorp's innovations can be integrated into other mining initiatives. For example, other mines could integrate waste-water recycling into their processing by purchasing Molycorp's SorbX technology ("SorbX-100"), decreasing the operational costs of refinement with a self-sufficient supply of ammonia, while lessening a refinery's environmental damage.
Bioleaching uses microbiological processes naturally performed by bacteria to remove rare earth ions (Ibrahim 2011). The cost of this process is remarkably low, and recovery rates can be as high as 90%. The process is often dismissed as it is much slower than other refinement methods (approximately 30 days (Das) in comparison to about ten hours for other methods), but bioleaching already accounts for 20% of copper on the market and can be sped up through additional research to find optimum operational temperatures of different bacterial species ("What is bioleaching?" 2011). Due to the complexity of the rare earth refinement process, research into integrating bioleaching with other common methods of purification could make this solution more viable (for example, unwanted minerals could first be removed using in-situ leaching, shortening the time needed for the bioleaching stage).
Solid Phase Extraction
Solid phase extraction (SPE) is a newly developed method of rare earth refinement, which, unlike solvent exchange, takes place with the minerals always in solid state. This solution utilizes a new filter technology produced by Intellimet LLC, in which mined materials are sorted by atomic densities and particle size, and the resulting piles are then purified according to their content, greatly increasing the process's overall efficiency. It has recently undergone testing with a junior exploration and mining company, UCore, that supported this as a very viable technology to be utilized in the near future. This solution can yield results within a relatively short time frame (~10 years), as the technology is already developed but not yet implemented. The precursor to SPE is solvent state extraction. The advantages to using this method are greater recovery rates and less waste (Acevedo 2002).
Implementation of These Developments
The Economic and Social Council of the UN will put into place international standards for environmental impact (storage of uranium in the form of paste tailings facilities and increased use of environmentally friendly methods such as bioleaching and SPE) and recovery rates (increased use of SPE and bioleaching). In order to make these standards achievable for smaller mines, The UN Economic and Social Council will provide loans for those companies or governments incapable of renovating tailings facilities or incorporating new technologies. Additionally, the distribution of information about the profit benefits of incorporating solid phase extraction and bioleaching methods into a mine's refinement processes is vital for motivation of private enterprises. These profit benefits can attributed to the lower operational costs and higher recovery rates of these methods.
Hopefully, this information distribution will motivate private funding for the continued research and development of bioleaching applications in the rare earth industries, to shorten and optimize the process for increased future feasibility. This research may also be supported by federal grants such as the US Government EFRI grant, currently available with a 2 million USD award ceiling to encourage innovation in "photosynthetic biorefineries" ("Emerging Frontiers...").
Cost and Logistics
The installment of bioleaching is approximately US$641 million for a design plant capacity of 150,000 metric tons per year, while installment of solid phase extraction technology requires US$300,000 to $800,000 for a capacity of 200,000 metric tons per year**(Dresher, "Increasing Metal..."). These are very rough estimates (the estimates for bioleaching are based on copper bioleaching results, and a direct correlation between price and production rate of machinery is not guaranteed) but the obvious discrepancy between bioleaching equipment costs and solid phase technology can be made up for by the fact that bioleaching plans for the present will only account for a fraction of the refinery's output, and that operational costs for bioleaching following installment are incredibly low. Based on these cost projections, the replacement of a third of the world's solvent-exchange refinement would only cost approximately US$ 2 million, and the replacement of a half would cost approximately US$ 3 million. The expense of such a replacement (likely more than projected due to factors other than purchase of machinery such as transportation and disposal of prior machinery) could be funded by local grants such as that of the Harry Frank Guggenheim Foundation (offering yearly research grants between 15 and 40 thousand USD per year ("Reasearch Grants") and subsidized by loans from the Social and Economic Council of the United Nations.
For traditional solvent-exchange methods, current operational costs for refinement of REEs are approximately $15 per refined pound of REE (Shuler), while the cost of bioleaching is about $0.20 per pound (Acevedo 2002). No concrete figures were offered for solid-phase extraction costs, as it is a very recent technology, but Intelligent Metallurgies claims them to be much lower than costs for solvent exchange ("Increasing Metal..."). However it is evident that profit from cheaper refinery methods would quickly balance the investment of transitioning from solvent-exchange to a more efficient method. Profit will motivate industries to convert their refinement processes and enable them to pay back the Economic and Social Council loans.
Goals and Benefits
Both of these processes are approximated to have a 95% recovery rate (Lifton, Das). If half of the rare earth industry converted to solid phase technologies or bioleaching, the average efficiency would be boosted to 75%, the goal for refinement improvement's contribution to the increase of global supply. A transition of this magnitude cannot take place all at once. However, if a goal year of 2030 was set, by which time one third of the world's refineries woud be using solid phase technologies or bioleaching (68% average recovery rate), and a goal year of 2040 was set at which time one half of these refineries would have converted, (75% average recovery rate), the world would be in a significantly less critical position with regard to the balance of supply and demand.
The replacement of one-half the world's refinement facilities with solid phase technologies, the development of bioleaching processes and the utilization of environmentally-friendly methods would cost approximately $10 million dollars. This plan, taking place over the next 30 years and funded by national, international and private sources, would result in an increase the global supply of rare earths by 36 percent.
**conversions from "gallons per minute" to "metric tons per year" based on estimates: daily operation of 2 hours and operation of refinery 180 days out of the year and an average density of purely REE ore equal 4.97 g/cm3 ("Bastnasite")
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