According to the studies conducted in the first phase (world supply and demand analysis of the rare earth elements, global applications of the rare earth elements, domestic industries consuming rare earth elements and amount of consumption, quality (purity) of rare earth elements required by domestic industries, domestic market analysis of the rare earth elements), it was found that the use of these elements is increasing sharply and traces of them can be seen in most new and advanced industries. Imports of these elements under custom tariffs are about $ 1 million/year, while large quantities of catalysts and magnets containing these elements are imported into the country under other tariffs. In other words, it can be said that the hidden consumption of these elements is much greater than the amount mentioned in the legal authorities. In general, it can be said that the global using order of these elements is as follows: catalysts (catalytic converter & petroleum catalysts), glass/ceramic, metallurgy/alloys, and phosphorus compounds.
In the production of catalysts; concentrates of rare earth elements, their oxide compounds as well as their oxalates can be used. In this research project; the first case e.g. concentrate of a mixture of rare earth elements was used to produce the catalytic converter washcoat as the most widely used and important product required by the market. The most important elements used in these catalysts are cerium and lanthanum. The performance of the produced sample was evaluated in comparison with the existing commercial sample and the role of rare earth metals and their importance in this field were explained. The results of this section provide new opportunities for the design and production of catalysts based on rare earth elements with exciting structures and functions, as well as the exploitation of new catalytic fields.
Cerium has the largest portion of all rare earth element concentrates in the world and, of course, has the most application among rare earth elements. In the oxide composition of rare earth elements obtained in the pilot of Iran Mineral Processing Research Center, this element has the highest amount. Due to the special atomic properties, the separation method of cerium from other rare earth elements is different. In this research project, an economic and industrial method for cerium separation was presented. A method for the separation of yttrium as one of the rare heavy elements in the concentrate was also presented. Yttrium separation was investigated by solvent extraction using PC88A and D2EHPA extractants and based on the results, separation using PC88A was suggested. Cerium separation was done by oxidation/precipitation method. In this method, cerium (III) was oxidized to cerium (IV) by using hydrogen peroxide and precipitated to Ce(OH)4 by the pH changing.
In the field of metallurgy, industries producing ferrosilicon magnesium are the main consumers of these elements in the form of mischmetal. Which shows the importance of implementing the rare earh mischmetal production project has been proposed as one of the important results of the present study.
In the field of alloys, magnets have a significant contribution in the use of these metals (especially neodymium and samarium). Due to the low amounts of these elements in the current concentrate, the subject can’t be investigated in the current conditions.
Details and results of the preparation of catalytic converter washcoat, economic methods to separate the cerium and yttrium elements, documentation of the optimal process used to extract rare earth elements in Karaj mineral processing research center, and the relevant maps are presented in the second phase of this research project.
In the third phase, preliminary feasibility study of the rare earth extraction project was performed based on the executive pilot documents. The results showed that the economy of the process, in addition to increasing the scale, depends on the price of chemicals, raw materials entering the factory, as well as the quality of the by-products of the project. In other words, if the ratio of ore to waste is low, the process will be an economic. But if this ratio is high, the process will no longer be economic, and in these circumstances, strategic issues will be decisive. The selection and supply of consumable chemicals must be done carefully. Selling by-products with acceptable market quality is very effective in profitability and economy of process. In this regard, it is necessary to pay attention to ammonium sulfate with a price share of 42% and titanium dioxide with a price share of 26%.