Extraction Of Valuable Elements Research Articles

A cleaner and sustainable method for recovering rare earth and cobalt from NdFeB leaching residues

NdFeB leaching residues (NLRs) is produced by the treatment of NdFeB waste by HCl preferential dissolution method, which contains about 1% rare earth and cobalt (Co). The extraction of valuable elements from the residue has a great impact on the sustainable utilization of rare-earth resources. In this study, a high-efficiency hydrometallurgy process was proposed to achieve a high conversion of valuable elements and the recycling of additives by reductive acid leaching. First, NLRs were characterized by the Bgrimm process mineralogy analyzing system, which confirmed that the iron oxide main phase encapsulates the rare earth phase. It was effective in destroying the main phase by chemical dissociation. In addition, the effects of temperature, reaction time, initial acid concentration, solid-liquid ratio (S/L), and reducing agent dosage on leaching efficiency were investigated. Under optimal conditions, 90.6% Co, 89.1% neodymium (Nd), 77.2% praseodymium (Pr), 88.7% cerium (Ce) and 83.8% iron (Fe) leached. The reaction mechanism and leaching kinetics in the leaching process were systematically explored. The kinetic analysis indicated the leaching reaction of Co and Fe was controlled by interfacial chemical reaction and the leaching reaction of Nd, Pr and Ce was controlled by internal diffusion. The activation energies of Co, Fe, Nd, Pr and Ce were 21.06, 18.07, 23.37, 20.56 and 18.52 kJ/mol. Furthermore, the reducing agent (copper powder) was successfully recovered by iron powder. The recovery rate of the copper powder was 99.93% and the purity was 93.42%. The proposed process has a promising application for industrial-scale recycling.

Tretiranje boksitnih ostataka - luženje - prvi deo

Introduction/purpose: Bauxite residue as a waste product from the aluminium industry produced through the Bayer process is mainly composed of iron oxide, titanium oxide, silicon oxide and undissolved alumina together with a wide range of other oxides and a minor content of rare earth elements, gallium, vanadium and scandium, which vary according to the country of origin of the bauxite. The extraction of valuable elements from bauxite residues and the minimisation of bauxite residues during different treatments are an open research field. Methods: Different hydrometallurgical and pyrometallurgical methods were used for the treatment of bauxite residues. In this study, the results of the hydrometallurgical treatment of bauxite residue from Alumina Zvornik using sulfuric acid and hydrochloric acid will be shown in order to study the change of the mineralogical composition. Leaching efficiency will be calculated using the ICP OES analysis. The XRD-Analysis was used for the characterization of the initial material and solid residues studying the change of the mineralogical phases. Results: Leaching of bauxite residues with sulphuric and hydrochloric acid leads partially to the change of mineralogical structure and the transfer of elements into a liquid phase. Natural precipitation of iron is observed over time. Silica gel formation is confirmed during leaching of bauxite residues with hydrochloric acid. Conclusion: A new research strategy for treating bauxite residue is needed in order to ensure a complete change of the initial minearlogical structure and the most efficient transfer of metals into a liquid phase.

A novel process for recovery of scandium, rare earth and niobium from Bayan Obo tailings: NaCl-Ca(OH)2-coal roasting and acid leaching

Bayan Obo tailings from Baotou Steel were discharged into tailings pond. The advantages of symbiotic resources have not been fully played. A large number of accumulated tailings also have a great impact on the surrounding environment. Comprehensive utilization of valuable elements in tailings becomes key measure to solve the above problems. Extraction of valuable elements, such as scandium, rare earth and niobium could be achieved by roasting Bayan Obo tailings in NaCl-Ca(OH)2-coal, followed by hydrochloric acid and sulfuric acid leaching. The phase transitions of main minerals were investigated. In the roasting process, niobium minerals were converted to CaTiO3-type compounds. The original rare earth minerals turned into rare earth oxide or rare earth silicate. Iron in Sc-Fe-bearing silicate migrated to CaFeSiO4, FeSiO3 and Fe3O4. Meanwhile, the structure of silicate was destroyed completely, which facilitated for leaching scandium. In the acid leaching process, newly generated niobium minerals were dissolved in sulfuric acid as niobium sulfate or niobic acid. For Bayan Obo tailings, under the optimal roasting and leaching conditions determined in this research, 97.6% Sc2O3, 97.18% REO and 40.1% Nb2O5 entered hydrochloric acid. 51.67% Nb2O5 was leached by concentrated sulfuric acid. Sc2O3 and REO were enriched in hydrochloric acid.

Extraction of Valuable Elements from Red Mud with a Focus on Using Liquid Media—A Review

Bauxite residue, known as red mud, is a by-product of alumina production using the Bayer process. Currently, its total global storage amounts to over 4.6 billion tons, including about 600 million tons in Russia. The total global storage of red mud occupies large areas, leading to environmental damage and increasing environmental risks. Moreover, it contains a significant amount of sodium, which is easily soluble in subsoil water; therefore, a sustainable approach for comprehensive recycling of red mud is necessary. The bauxite residue contains valuable elements, such as aluminum, titanium, and scandium, which can be recovered using liquid media. In recent years, many methods of recovery of these elements from this waste have been proposed. This paper provides a critical review of hydrometallurgical, solvometallurgical, and complex methods for the recovery of valuable components from red mud, namely, aluminum, titanium, sodium, and rare and rare-earth elements. These methods include leaching using alkaline or acid solutions, ionic liquids, and biological organisms, in addition to red mud leaching solutions by extraction and sorption methods. Advantages and disadvantages of these processes in terms of their environmental impact are discussed.

Complex Processing of Copper Smelting Slags with Obtaining of Cast Iron Grinding Media and Proppants


 
 
 The Ural region has a large number of metallurgical companies. The extraction of metals from ore is always accompanied by the accumulation of wastes. Currently, most of the wastes are stored in dumps and storage facilities forming technogenic deposits. One such that occupies huge areas is copper slag from the copper-smelting production. According to current estimations, about 2.2 tons of slag is formed for each ton of copper produced and about 24 million tons are produced annually [1]. In general, a copper slag contains about 35-45% iron and 0.4-0.5 copper, which indicates that this is a valuable secondary resource for recycling and utilization [33]. However, more than 80% of copper slag is not utilized, which makes it possible to consider this waste not only as a valuable material, but also as a potential hazard for the environment; it contaminates the soil and water with heavy elements [8]. Currently, only small amounts of the waste are recycled. In addition, technologies do not allow the complete extraction of valuable elements. This offers potential for the development of new highly efficient technologies for processing copper smelting wastes with extraction of valuable elements such as iron (Fe). Improvement of Fe quality requires a decrease in non-ferrous metal content, especially Cu. In recent years, extensive research was directed at the extraction of valuable materials from copper slags by high-temperature firing of copper conglomerates with subsequent magnetic separation or leaching of non-ferrous metals. However, these studies do not allow the complete processing of copper smelting slags. This work studies the production of iron-containing briquettes from copper-smelting slags, and their subsequent processing to obtain valuable products for metallurgical and oil companies.
 Keywords: briquette, reduction, cast iron, proppants
 
 

Methods for Extracting Valuable Elements (Fe, Al, Na, Ti) From Red Mud

This article summarizes the results of a systematic review of the literature in one particular application area – the extraction of valuable elements (Fe, Al, Na, Ti) from red mud. The analysis showed that depending on the composition of the bauxite being processed and the instrumentaltechnological scheme for producing alumina, the content of iron oxide (Fe2O3) varies from 7 to 70 % by weight, aluminum oxide (Al2O3) – from 2 to 33 % by weight, titanium oxide (TiO2) from 2.2 to 25 % wt., sodium oxide (Na2O) up to 12.5 % wt. The achieved maximum percentage of iron extraction is 97.5 %, aluminum – 89.7 %, sodium – 96.4 %, titanium – 97 %. It was noted that all practical studies were carried out in laboratory conditions only. As the most effective, technological proposals have been allocated for complex processing of red mud, including processes of smelting reduction, magnetic separation, leaching with mineral (HCl, H2SO4, HNO3) and organic (H2C2O4) acids. In modern studies, it is proposed to use microwave, ultrasound, or plasma technologies in recycling. As a result of the work, a systematic table was proposed on methods for extracting Fe, Al, Na, Ti from red mud. Suggestions are made on the criteria of technology that would have environmental, energy and economic benefits.

Kırmızı Çamurdan Değerli Elementlerin Geri Kazanımına Yönelik Yapılan Araştırmaların Derlenmesi

An alternative application is the recovery of valuable elements from red mud. Red mud contains appreciable amounts of industrial metals such as Fe, Al and Ti and rare earth elements like Sc, Ce and La. Extensive researches have been carried out into the topic worldwide. Parallel with the other countries worldwide, researches have also been carried out in Turkey on the utilization of Seydisehir red mud. Application of red mud in construction materials, ceramic and glass industry, water purification and as coloring or catalytic agent has been proposed in the literature. However, these applications are not noticed by the companies and investors because the relatively low economic value of the products or because of their limited market which cannot respond to the huge amounts of red mud disposal. Red mud is a waste material of the Bayer process for alumina production from bauxite ore. Red mud is generally pumped to disposal in an artificial pond. In addition to the vast area of the land occupied, red mud pollutes water resources and leads to environmental issues because of its high alkalinity. This paper reviews and classifies the researches into the extraction of valuable elements from the red mud carried out in Turkey and worldwide.

New technology of extracting the amount of rare earth metals from the red mud

The paper outlined the environmental and economic problems associated with red mud - the waste generated in processing of bauxite ore for aluminum production. The chemical analysis of red mud has identified a number of useful elements including rare earth metals. The electromembrane technology of red mud processing with extraction of valuable elements is described. A possible scheme of separation of these metals through electrolysis is also given.

Extraction of Valuable elements in Spent Nuclear Fuel by using Pyridine Resin

Extraction of Valuable elements in Spent Nuclear Fuel by using Pyridine Resin