Journal of ChemicalReyhan Technology Ozbas, and Emek Metallurgy, M. Derun 56, 4, 2021, 845-852 LEACHING OF LITHIUM AND RUBIDIUM ELEMENTS FROM BORON PRODUCTION WASTES Reyhan Ozbas, Emek M. Derun Department of Chemical Engineering, Received 14 November 2020 Faculty of Chemical and Metallurgical Engineering Yildiz Technical University, Accepted 08 March 2021 Istanbul, Turkey E-mail: [email protected] ABSTRACT In this study it is aimed to recover rare elements and boron with high potential for evaluation from the contents of different boron wastes obtained from Eti Mine Works. For this purpose, raw material analysis and then rare ele- ments and boron recovery by different methods and instrumental devices were performed. Some boron waste sites are remarkable for being rich in rare elements such as lithium and rubidium. For the most efficient utilization of such wastes, samples were obtained from the Eti Mine Kırka Plant for the recovery of both boron and rare elements by using roasting-leaching and acid-leaching methods. The chemical analysis results of borax clay for the main oxides are: 3.3 % boron oxide (B2O3), 0.27 % lithium (Li2O), and 0.0221 % rubidium oxide (Rb2O); in the waste samples the main oxides are 11 % boron oxide (B2O3), 17 % lithium (Li2O), and 0.0264 % rubidium oxide (Rb2O). The XRD analysis of the samples showed predominantly the presence of dolomite (CaMg(CO3)2) and tincalconite (Na2B4O7.5H2O) minerals. After roasting-water leaching of these samples, it was determined that the sample of bo- rax clay contained up to 75 ppm lithium and the boron waste sample contained up to 124 ppm lithium. After HNO3 leaching it was observed that the best lithium amount passing from the borax clay sample to the solution was 276,7 ppm. In addition to lithium, the presence of rubidium and cesium as trace elements was noticed. It was observed that the best rubidium amount passing from boron waste to the solution was 3.67 ppm with a mixture of Calcium Chloride Dihydrate (CaCl2.2H2O) and Borogypsum (CaSO4.2H2O). The best amount of rubidium that passed from borax clay to solution was found to be 3.58 ppm with a mixture of Calcium Chloride Dihydrate (CaCl2.2H2O) and Borogypsum (CaSO4.2H2O). Keywords: boron clays, boron wastes, lithium, rubidium, roasting-water leaching method, acid leaching. INTRODUCTION possible, the wastes must be properly disposed of. There have been several attempts to use boron wastes 72 % of the world’s total boron reserves are found and some main strategies were formerly applied [2 - 5]. in the inland areas of the Aegean region of Turkey, The Emet/Kütahya boron-containing clays were used in and borax constitutes the major part of these reserves studies conducted with samples from the region and it [1]. Colemanite is found in the Emet, Bigadiç, and was shown that rubidium metal was dominant. Rubidium Kestelek deposits, which are extracted by the world’s was extracted from picric acid with 18-Crown-6 (0.1 M) boron leader, Eti Mine, and enriched and ground in a in nitrobenzene and separated from the organic phase high-tech concentrator plant. Because boron, the most with 2 M hydraulic acid. The best rubidium extraction important natural resource of Turkey, is a mineral asset obtained was 89.52 % [4]. with increasing production and demand, the amount of Rare elements can be recovered from industrial waste produced as a result of the enrichment processes wastes as well as from electronic wastes [6, 7]. In a study is also increasing every year. Utilization of enrichment conducted on this subject, gold was recovered from the plant wastes is now a prominent technique; if it is not shredder light fraction of an E-waste recycling plant with 845 Journal of Chemical Technology and Metallurgy, 56, 4, 2021 flotation-ammonium thiosulfate leaching [8]. ent processes developed for the extraction of lithium and The presence and distribution of lithium was investi- related metals from both primary and secondary sources. gated within the scope of Turkey’s borates in some non- Acid, alkaline, and chlorination processes and lithium Neogene basins and lakes. When clay samples in Turkish extraction from primary sources such as adsorption, borate deposits, the Soma lignite basin and Beypazarı precipitation, and ions and ores/minerals (spodumene, trona basin, and Acigöl, Salda, Yarişçi, Burdur, Eğirdir, petalite, and lepidolite) from brine received particular Tersakan, Bolluk, Karapınar (Acigöl), and Tuzgölü attention. Issues related to the use of other sources such were analyzed, lithium values of 0.17 % were obtained as bitterns and seawater were highlighted. The hot from the clays of the examined borate deposits. A value water leaching of calcines indicated that increasing the of 0.58 % Li2O was found, and the lake water samples calcination temperature had a considerable effect on contained 0.30 to 325 mg L-1 Li+ [9]. the dissolution of lithium. The leaching of lithium from The compressive and flexural strength, thermal prop- lepidolite was notably higher than that from spodumene erties, and pore structure of mortars modified with boron [17]. As for secondary sources, industrial processes were waste CuO nanoparticles were examined. The addition followed, and more recent developments have aimed at of calcined and non-calcined borogypsum to clinker and recovering lithium from lithium-ion batteries (LiBs). its effects on cement mortar were also studied [10, 11]. In particular, the pretreatment of spent LiBs, filtration The chlorination process is technologically feasible of metals in acids different from cathode materials, and and has the potential for efficient applications. Chlorina- separation of lithium and other metals from leaching tion roasting-water leaching is used to obtain lithium solutions have been discussed [18]. It is known that from lepidolite. The microstructures of lepidolite and lithium in smectite clays is contained in hectorite. In a roasted materials were characterized by X-ray diffraction study carried out in this area, 89 % of lithium in clay (XRD). Various parameters such as chlorination roasting samples was dissolved from the Kırka beds, while 71 temperature, duration, and type and amount of chlorina- % of the lithium in samples from the Bigadiç beds was tion agent have been optimized [12]. Lepidolite is the dissolved [19]. Rubidium is acquired as a by-product in most common source for rare elements such as lithium, the processing of lepidolite and pollucite. It is found in rubidium, cesium, and potassium [13, 14]. several pegmatite regions. Pegmatite deposits are ex- In a study carried out by applying a chlorination plored and operated primarily for their Li contents. Since process for the co-extraction of Li, Rb, Cs, and K, the the chemical structure of rubidium is mostly similar to lepidolite concentrate was roasted at a moderately high adjacent alkali metals, it is extracted only from their temperature with mixed CaCl2 and NaCl chlorinat- deposits, from lepidolite [(K, Rb) Li2AlSi4O10F2] and ing agent, followed by water filtration. Under optimal pollucite (Cs2Al2Si4O12) deposits, and is separated after conditions, the extraction efficiencies of Li, Rb, Cs, the staged chemical processing of cesium and potassium and K reached 92.49 %, 98.04 %, 98.33 %, and 92.90 [20]. Trace element analysis of industrial boron wastes %, respectively [15]. In another study, the recovery of revealed that rubidium was predominant in boron clay. alkali metals and the leaching kinetics of lithium from Although the results are different from each other, it sulfuric acid solution under atmospheric pressure were has been demonstrated that the sulfuric acid leaching investigated from lepidolite in Yichun, Jiangxi Province, method may be an alternative method [21]. In recent China. The results showed that the recoveries of alkali years, the adsorption method is also encountered in metals were achieved under the following leaching con- rubidium extraction [22, 23]. In a study related to this ditions: mass ratio of lepidolite with particle size of less method, the adsorption of rubidium was investigated than 180 µm to sulfuric acid of 1.2, leaching temperature using rubidium(I) potassium cobalt hexacyanoferrate .[and leaching time (K2[CoFe(CN)6])[23 ,1׃of 411 K, liquid to solid ratio of 2.5 of 10 h. Under the optimal conditions for the leaching In this study, it is aimed to analyze rare elements experiments, the leaching rates of lithium, potassium, and boron in different wastes obtained from Eti Maden rubidium, and cesium were 94.18 %, 93.70 %, 91.81 %, Kırka Enterprises, first by analyzing raw materials with and 89.22 %, respectively [16]. A comprehensive review instrumental devices and then via metal recovery by of lithium extraction summarized the state of the differ- different methods. In this study boron in Turkey for the 846 Reyhan Ozbas, Emek M. Derun production of lithium carbonate is investigating the use Lithium Recovery experiments with Roasting-Water of waste as raw material. Leaching Method For the limestone-gypsum roasting-water leaching EXPERIMENTAL method, the proportions of the mixtures were prepared as shown in Table 2. In these mixtures clays (I), borax Characteristic of Wastes pentahydrate production solid wastes (II), and calcium Preparation of Samples carbonate (CaCO3) and borogypsum (CaSO4.2H2O) Clays (I) and borax pentahydrate production solid in the borax zone were used. After the mixtures were wastes (II) in the borax zone were obtained from Kırka ground, the roasting process was carried out in a high- Borax Enterprises. Clays and borax pentahydrate pro- temperature oven for 2 hours at 900°C. In these mixtures, duction solid wastes in the borax zone were taken from the lithium in the borax clay is released and reacted with the plant as samples. Each sample was first dried at the sulfur in the gypsum to form Li2SO4. This Li2SO4 105°C. After drying, the samples were crushed to sizes is dissolved in water and lithium is transferred to the smaller than 1.1 cm in a jaw crusher and then milled to solution.