【正文】 23 附錄 Extraction of niobium from sulfate leach liquor of Egyptian ore sample by triazoloquinazolinone 1 Introduction In nature, niobium almost invariably occurs as plex oxide minerals in association with tantalum. The most mon geological occurrence of both suits of minerals is in association with Pegmatites. Niobium ores are processed by physically and chemically breaking down the ore to form salts or oxides。 and these may be sold, or further processed to reduce the salts to the respective metals. Niobium is considered to cover the vast majority of material in the industry. Its demand is at all time high and continue to rise. Mining and processing capacity is being increased to satisfy this situation, primarily by CBMM with its further expansion to 185 t/a Nb2O5 scheduled in 2021. Niobium is extracted from the source materials, imported concentrates, and tin slags. A large number of solvent extraction processes using different binations of various anic reagents and mineral acids have been investigated for the extraction and separation of niobium. The reagents that have been shown to be suitable for the extraction and separation of niobium can be grouped broadly into two categories. One includes neutral oxygenated extractants, such as ketones, tributyl phosphate(TBP), triocytlphosphine oxide(TOPO), Noxides, and sulfoxides. The other category includes long chain aliphatic and aromatic amines that contain basic nitrogen capable of forming amine salts。 . trioctylamine(TOA) and tribenzylamine (TBA). Processes based on ketones and TBP have been found acceptance in industrialscale operations. Synthesis of triazolo quinazolinone as condensed ring systems is of considerable interest because of the diverse range of their biological properties. The present work deals with the synthesis of multidentate heterocyclic nitrogen ligand. For this purpose, sulfate leach liquor was prepared from leaching a multiple oxides niobium bearing minerals obtained from KadaboraCentral Eastern of Egypt. 內(nèi)蒙古科技大學畢業(yè)論文 24 2 Experimental Synthesis of extractant The β diketone 1,3 cyclohexane dione was selected as starting material to prepare a heterocyclic nitrogen pound to be used as an extractant for niobium ions. A suspension of 1,3 cyclohexane dione was heated under reflux with dimethyl formamide dimethyl acetal(DMF DMA) for 3 h. After cooling to room temperature, the obtained enaminone was properly crystallized from hexane. Next, it reacted under reflux with aminotriazole in ethanol for 6 h followed by the addition of catalytic amount of pipredine. The residual solid was taken in ethanol and washed with distilled water. After filtration, recrystallization from DMF/water was done to afford the corresponding fused heterocyclic 8,9dihydro[1,2,4]triazolo[1,5a]quinazolin 6(7H)one symbolized by TQ. Characteristic of ore sample The ore sample used in this study was collected from a multiple oxide mineralization Kadabora Batholiths situated in the Eastern Desert of Egypt. It was ground to＜ 74 μm and was subjected to Xray diffraction analysis using Philips Xray diffractometer model PW 223/20 operated at 40 kV and 20 mA. It revealed the presence of multiple oxides refractory minerals. The elemental analysis was done using scanning electron microscope (CAM SCAN series 4 ISIS 200 E/X system with pentajet detector, University of Leeds, England). Table 1 summarizes the obtained minerals and the average elemental chemical position of different sample spots. Table 1 Mineralogical and elemental position of ore sample collected from Kadabora Batholiths in Eastern Desert of Egypt Mineralogical position Samarskite (ASTM card ) Fergusonite (ASTM card No. 9443) Betafite (ASTM card No. 8300) Pyrochlore (ASTM card ) Mass fraction of elemental position*/% 內(nèi)蒙古科技大學畢業(yè)論文 25 C O Na Al Si Ca Ti Fe Y Nb Ce Nd Ta U Recovery of niobium The ground ore sample (15 g) was mixed with 100mL sulfuric acid ( mol/L). The obtained slurry was agitated for 2 h at 150℃ and the insoluble residue left behind was separated by filtration. The chemical position of the obtained leach liquor is given in Table 2. Several batch solvent extraction experiments were done by using the synthesized anic multidentate extractant TQ dissolved in methylene chloride as diluent. The extraction step was followed by the stripping step in which equal volumes of the loaded extractant and the stripping agents (distilled water, mol/L HF or ) were shaken for 15 min to back extract niobium. The final step in the treatment is represented by precipitation of niobium from the strip solution using 33% ammonium hydroxide. The obtained final product was analyzed for its chemical position and purity by SEM . The determination of niobium concentration whether in the prepared leach liquors or in the aqueous raffinate solutions (after extraction) or else in the stripping solutions was performed by pyrogallol. The analysis was performed with a double beam UVVIS recording Shimadzu UV160A spectrophotometer Table 2 Some elements of interest posed (100 mL) ofsulfate leach liquor Element Nb Ta Ti Ce Y U Fe Concentration/(gL1) Recovery/% 69,8 3 Results and discussion Extraction experiments Cyclohexone was previously used for extracting 70% niobium from sulfate leach liquor in presence of ammonium nitrate. In the present study, 1,3 cyclohexane dione was examined 內(nèi)蒙古科技大學畢業(yè)論文 26 for extracting niobium. Its extraction efficiency did not exceed 5% by shaking equal volumes of the anic phase and sulfate leach liquor ( mol/L H2SO4) containing g/L Nb for 15 min. Thisβ diketone was used as start for synthesizing TQ. The latter was prepared as % in methylene chloride and was used to study the influence of different extraction conditions in impr