Comparative study for leaching processes of uranium, copper and cadmium from gibbsite ore material of Talet Seleim,

In this paper, leaching characteristics are presented, and a cost-effective process for extracting uranium, copper, and cadmium from Talet Seleim’s Gibbsite is developed. H 2 SO 4 was chosen as the preferable leaching agent based on the agitation experiment’s findings. The leaching efficiencies of U, Cu, and Cd attained 95%, 90%, and 89%, respectively, under the investigated ideal circumstances. Kinetic study of leaching process proved diffusion controlling mechanisms with activation energies: 29.59, 29.30, and 34.84 kJ/mol, respectively. U was recovered using Amberlite IRA 400, while Cu and Cd were precipitated from Talet Seleim’s gibbsite’s sulphate leachate. Finally, the tentative treatment procedure's preliminary flowsheet was then given.


Introduction
High-tech industries are growing in demand of valuable, strategic metals, and rare earth metals. More specifically, these metals are widely used in electronic devices, alloys, metallurgy and the nuclear power industry [1][2][3][4]. There are two processes for recovering metal from solid waste or minerals: pyrometallurgy and hydrometallurgy (chemical leaching or bioleaching) [5]. Hydrometallurgical methods are widely used to extract metal from low-grade deposits, dilute effluents (uranium leachates, metallurgy effluents and wastes) and from secondary resources (coal and phosphate ore residues, etc.) [6] as depicted in Fig. 1: (a) first leaching using in most cases acidic solutions, followed by (b) a series of separation techniques including: solid-phase extraction, sorption, co-precipitation, solvent extraction, ion-imprinted resin, biosorption, extractant impregnated resins and impregnated? or emulsion membranes [5]. As an extractive metallurgy, pyrometallurgy is centered on extracting and purifying metals using high temperatures. Based on the technology, the following categories can be used to group pyrometallurgical processes: roasting, smelting, calcining, and refining [7]. The oxides of less reactive elements including iron, copper, zinc, chromium, tin, and manganese are examples of elements recovered via pyrometallurgical methods. The charge materials, method, operating conditions, as well as the physical shape, size, and orientation of the vessel, all affect how copper is pyrometallurgically processed across the world. To create blister copper or other end products, a plant may operate in batch, semi-continuous, or continuously [8] Nuclear power facilities are being expanded to satisfy expanding worldwide energy demand. Uranium is a key resource for the nuclear power plants, since it is inexpensive and produces a large amount of electricity. As a result, future researchers in developed countries will benefit and more uranium extraction and separation procedures are being researched and developed in emerging countries. This issue has become a hot topic in terms of environmental protection and nuclear fuel conservation [9][10][11][12][13]. Uranium may be extracted from its ores via acid or alkaline leaching [14,15]. The optimal reagent is determining by a number of technical and economic factors, including uranium mineral type, gangues, reagent availability and prices, oxidant requirements, and equipment construction materials [11].
These gibbsite ores include large amounts of valuable metals (e.g. Mn, Zn, Co, Cu, Ni, V, U, and REEs) in addition to Al (the main resource). Gibbsite ore contains REE (⁓ 776 ppm) and U (⁓ 257 ppm) [14,16]. The value of Gibbsite ore material is gaining popularity, not only for the purpose of recovering uranium and/or precious metals, but also for other advantages such as reducing the environmental effect of mining residue deposits [4]. The gibbsite mining leach liquor reveals the existence of U, Cu, and Cd that may be utilized to optimize the utilization and reduce the cost effectiveness of uranium extraction process.
Copper is found in nature in a variety mixture of Cu, Fe, S, and additional components: Chalcopyrite (CuFeS 2 ) is the most prevalent of these naturally occurring compounds, accounting for over 70% of all copper resources [17]. Cadmium metal and salts have grown in popularity as a result of their wide range of civil and industrial applications, as well as in the nuclear industry [18,19]. Cadmium is mostly produced as a by-product of other metals' metallurgical processing like copper, lead and zinc [6,18,20,21]. Cadmium is a rare metal that is rather uncommon in the crust of the earth, where concentrations of it can be found ranging from 0.08 to 0.5 mg/L, despite its toxicity [22,23]. Furthermore, it is used in the manufacture of sheets that regulate/control nuclear fission reactions, due to its ability to absorb thermal neutrons [18,21,23].
Currently, a number of effective techniques for recovering copper are available, including adsorption processes [3,24,25], chemical precipitation [26,27]; ion exchange [3,28,29], reverse osmosis [30], and electrodialysis [31]. However, they frequently need significant investment and produce a lot of waste products. More than a third of all copper is now produced from leachates, which are typically concentrated using solvent extraction and stripped of their copper content using traditional electrowinning [5].

4+
, in the pH range of 8-11, which are highly stable anionic and cationic complexes according to Francis et al. [35], and Li et al. [36].
Orabi et al. [16] investigated the Cu/U mineralization and their recovery using an alkaline leaching. The significant an alkaline leaching aspects were investigated using a Na 2 CO 3 /(NH 4 )HCO 3 mixture. El-Sheikh et al. [14] used two sequential alkaline leaching methods to study the selective recovery of U and Cu from carbonate-rich latosol ore material from Abu Thor region of southwestern Sinai mineralization. In fact, it is possible to separate Cd 2+ from the acidic solutions containing Cu 2+ by direct precipitation using sulfide solution depending upon the large difference in their solubility products (Ksp CuS : 2.4 × 10 −36 and Ksp CdS : 7.9 × 10 −27 ) [20,21].
As its diisobutyldithiophosphinate complex, Rickelton [37] discovered a selective way of eliminating cadmium through precipitation. Younesi et al. [38] used zinc dust to remove cadmium in a pH range of 5.2-5.4 at varied concentrations. Because of the growing a fascination with using metals is removed from aqueous media by continuous electrolysis, electrowinning has become one of the most often used methods for extracting cadmium from liquors [2,39]. However, certain precipitation approaches for selective cadmium extraction from Nickel-Cadmium sulfate solution are being investigated [27,40]. Mauchauffée et al. [27], and Moradkhani et al. [39], researched selective zinc alkaline leaching optimization and cadmium sponge recovery by electrowinning from cold filter cake residue.
This study is shifted to (1) explain the potentiality of recovery of the metal values (uranium, copper, and cadmium) from the Gibbsite ore material at Talet Seleim using various leaching techniques namely acid leaching, alkaline leaching and salt roasting, (2) The optimization of the factors for uranium, copper and cadmium leaching such as concentration of acid, time of leaching, the ratio of solid to liquid (S/L), stirring speed, and leaching temperature, (3) The preferred lixiviant in the process of leaching the metal values was known and (4) Then kinetics, reaction mechanism, kinetic model and activation energy studies for uranium, copper and cadmium leaching were established.

Ore characterization
Talet Seleim area is situated in the southwestern Sinai, Egypt between 33°20′ and 33°25′ E longitudes and 29°00′-29°05′ N latitudes. It is covered mainly by early Carboniferous Um Bogma Formation. This formation is consisted of a sequence of three lithological units. The middle unit is composed of ferruginous shale with marly lenses and extends more than 2 km and of 4-6 m thickness. The presence of a variety of metal values, such as U, Zn, REEs, Mn, Al, Co, Ni, and Cu, distinguishes this rock block [14,33].
The provided ore material that has been collected from Gibbsite Ore materials of Talet Seleim area was first subjected to crushing by a laboratory jaw-crusher before its grinding to 200 µm particle size. The latter was then properly quartered to have a representative sample for the chemical analyses. The major oxides have been analyzed using the traditional wet chemical methods of Shapiro and Brannock [16]. The SiO 2 , TiO 2 , Al 2 O 3 and P 2 O 5 were spectrophoto-metrically analyzed while Na 2 O and K 2 O were analyzed by flame photometry. On the other hand, the Fe 2 O 3 , MgO and CaO were analyzed titrimetrically against a standard solution of EDTA. The X-ray fluorescence technique (XRF), model Rigaku EDXRF spectrometer NEX CG. was used to analyze trace elements in solid sample.

Leaching procedures
Many hydrometallurgical procedures have been developed in order to meet the goal of dissolving the highest amount of U, Cu, and Cd components under ideal conditions with the least amount of unwanted gangues dissolving. Acid, alkaline leaching and salt roasting technology was performed to achieve the high leaching efficiency of U, Cu and Cd. Each acid and alkaline experiment with leaching was carried out by agitating a weighed quantity of the ground material (5 g) with different acid and alkaline concentrations, distinct solid/liquid ratios (S/L) over various time durations at various temperatures. Finally, the residue is filtered and rinsed with distilled water. Quantitative analysis of leachable metal ion concentrations in the obtained liquid was determined. The roasting with alkali method was carried out by combining the working ore with NaOH (solid) and heating it to a slightly higher temperature for various durations of time. After that, water leaching was used to dissolve the U, Cu, and Cd content in the cooled roasted matrix. The working ore sample was used in all of the experimental roasting methods at a consistent weight (5 g).

Control analysis
Uranium in the representative ore material sample as well as in the different stream solutions during its processing was tested using an oxidimetric titration when a diphenylamine sulfonate indication is present against ammonium metavanadate [41,42]. On the other hand, the atomic absorption spectrometer was used to measure Cu and Cd (Unicam 969, England) [43].

Working sample characterization
The comprehensive chemical examination of a typical sample (Gibbsite ore material) was performed using the above mentioned procedures and the results are displayed in Table 1. Concentrations of silica, alumina, Fe 2 O 3 , and loss of ignition, as determined by these data, are 35.42%, 19.45%, 17.16%, and 18.89% respectively. Also, U has a concentration 0.06%, Cu 0.15% and Cd 0.02%. XRF (X-ray fluorescence) examinations of various trace elements reveal that Zn, Ni, V and Σ REEs; namely; 5000, 1761, 1006 and 2250 ppm, respectively.

Factors influencing the leachability of U, Cu, and Cd
Acid agitation leaching Effect of acid type Influence of acid type upon U, Cu, and Cd dissolution efficiency from the ore sample was per- Therefore we use it in the further leaching process because it is a strong and inexpensive acid. Other acid such as HCl is not preferred due to its corrosive nature and HNO 3 is costlier than H 2 SO 4 [44] Effect of acid concentration H 2 SO 4 concentration employed to investigate its impact on the agitation leaching efficiency of U, Cu, and Cd values was varied from 80 to 240 g/L. For the other leaching conditions, they were set for a period of 2 h at 80 °C, using an ore processed to 200 µm particle size and a stirring speed of 500 rpm/min, within a S/L ratio of 1/4. Figure 2b illustrates the findings as following; the leaching efficiencies are directly affected by the acid concentration on the metal values. The leaching efficiency of U, Cu, and Cd improved from 60 to 90%, 55 to 85% and 45 to 83%, respectively, when the acid concentration was increased from 80 to 200 g/L. On the other hand, increasing H 2 SO 4 content (to 240 g/L) resulted in decreasing the U, Cu, and Cd leaching efficiency. In practical terms, sulphate complexing reactions are favoured over uranium, copper and cadmium hydrolysis when excess sulphate ions present, also the higher acidic concentration may result in dissolving higher percentage of undesirable elements [45,46]. The expected chemical reactions are illustrated in the following equilibrium Eqs. (1-6): (1)

Effect of agitation time
The influence of agitation period on U, Cu, and Cd leaching was examined in order to estimate the time it takes for U, Cu, and Cd to attain their maximum solubility. As a result, multiple time periods ranging from 30 to 240 min were studied using the following testing parameters: 200 µm particle size, 200 g/L sulfuric acid solution, 1/4 solid/liquid ratio, 500 rpm/min stirring speed and 80 °C reaction temperature. The obtained results show in Fig. 2c, have been observed that the U, Cu and Cd leaching efficiency has increased from about 60 to 95%, 60 to 90% and from 68 to 89% respectively at 180 min. Further increase in time to 4 h will decrease the dissolution efficiency of both U, Cu and Cd to 90, 85 and 80% respectively. As a result, the optimal condition for following uranium, copper and cadmium ions dissolving tests is 180 min of contact time.
Effect of temperature Seven acid experiments on leaching were carried out to study the impact of temperature on the leaching efficiencies of U, Cu, and Cd leaching from the working sample in the vicinity of ambient temperature (approximately 25 °C) to 90 °C. Other leaching parameters used in these experiments were 200 m particle size, 200 g/L acid concentration, 1/4 solid/liquid ratio, and 500 rpm/ min stirring speed for a 180 min dissolution duration. The leaching rate increases dramatically at higher reaction temperatures, according to the results presented in Fig. 2d. The amount of U, Cu, and Cd leaching from the working sample is significantly influenced by reaction temperature. The U, Cu and Cd leaching efficiencies increase from 45, 50, 45 to 95%, 90% and 89% respectively as temperature increase from 25 to 80 °C. Improving the U leach-ability with increasing temperature might be due to increase in mobility of ions under the effect of given energy [47]. Further increase in temperature to 90 °C decreased U, Cu and Cd leaching efficiencies to 92%, 90% and 85% respectively as increasing the temperature enhances the solubility of the undesirable impurities, such as sulfides, arsenide, silicates, chlorites, clays, and phosphates [48,49]. As a result, under the aforementioned conditions, the optimum leaching temperature is 80 °C.
Effect of solid/liquid ratio The most significant experimental component is the solid/liquid ratio's (S/L) role in the leaching process. Density was related to the productivity of the leaching process. It changes at constant leach solution depending on the concentration of the ore sample (acid or base or water, etc.) Process will be influenced by surface area per unit volume over a given period of time [9,15]. Under the other optimum settings, the effect of changing the S/L (solid/liquid) ratio from 1/2 to 1/5 is investigated. Figure 2e depicts the acquired results, which demonstrate that the U, Cu and Cd leaching efficiency has risen from 75 to 95%, 65 to 90% and 78 to 89% respectively with a solid/liquid ratio of 1/4. The possible reason is that the mass transfer at the solid-liquid interface becomes faster at a higher S/L ratio, which therefore increases the mass transfer driving force of U, Cu and Cd from solid to liquid phase [50]. The total amount of U extracted from solid phase is therefore increased. The leaching efficiency of U, Cu, and Cd is reduced when the S/L ratio is increased to 1/5 due to the dissolution of interfering elements compound e.g. Al, Fe and Zn [21,47]. As a result, a S/L ratio of 1/4 is regarded appropriate.

Effect of stirring speed
The influence of stirring speed on U, Cu, and C leaching was investigated using speeds ranging from 200 to 600 rpm/min while maintaining constant the concentration of solution, the temperature of reaction, solid/liquid ratio, and leaching period. Figure 2f depicts the results, when the agitation speed was increased from 200 to 500 rpm uranium, copper, and cadmium leaching efficiency rose from 75 to 95%, 65 to 90%, and 70 to 89%, respectively. The best U, Cu, and Cd leaching conditions giving about 95% 90%, and 89%, correspondingly can be obtained under the experimental conditions: acid concentration: 200 g/L, grain size: − 200 µm, leaching temperature: 80 °C, leaching time: 3 h, Solid/liquid ratio: 1/4, and stirring speed: 500 rpm. Based on the aforesaid leaching method studied on Talet Seleim mineralized sample.

Alkaline leaching
Effect of different alkaline reagents It's likely that the impact of several reagents for alkaline leaching, either alone or in conjunction, on uranium, copper, and cadmium leaching efficiency has been explored. The additional leaching parameters in these trials were set at 120 min of agitation, temperature of leaching was 60 °C, with a 1/5 solid/liquid ratio of 4:1 mixed reagent and the leaching agents' concentration of 150 g/L. Figure 3a shows the U, Cu, and Cd leaching efficiencies obtained. According to the latter, the best leaching reagent is a 4:1 Na 2 CO 3 and (NH 4 )HCO 3 mixture, which achieved a 75%, 65%, and 63% leaching for U, Cu, and Cd respectively. This behavior is consistent with what prior investigators have observed [14,16].

Effect of solid/solid ratio of Na 2 CO 3 and (NH 4 )HCO 3 mixture
The effect of various Na 2 CO 3 /(NH 4 )HCO 3 concentra-tions on the working ore sample's leaching efficiencies for uranium, copper, and cadmium was investigated using solid/ solid ratios of Na 2 CO 3 and (NH 4 )HCO 3 mixtures of 1:2, 1:3, 1:4, 2:1, 3:1, 4:1 and 1:5. The additional leaching parameters were set at 120 min of agitation time, the temperature of leaching was 60 °C with a solid/liquid ratio of 1/5. Figure 3b shows the leaching efficiency of U, Cu, and Cd, and shows that the optimal S/S ratio is 4/1. The leaching efficiency of U has reached 75% under these conditions, with Cu and Cd dissolving efficiencies of 65% and 63%, respectively.

Effect of Na 2 CO 3 and (NH 4 )HCO 3 concentration
In the metals leaching process, the alkaline concentration is quite significant. Concentration of alkali lixiviant's effect on U, Cu, and Cd realizing from the working ore sample was studied using different concentrations of Na 2 CO 3 /(NH 4 )HCO 3 mixture ranged from 50 to 250 g/L were employed to look at the impact of alkaline concentrations upon leaching efficiencies of U, Cu, and Cd leaching based on the current ore sample. The other leaching parameters were maintained at a Solid/ liquid ratio of 1/5 of 4:1 Na 2 CO 3 /(NH 4 )HCO 3 and an agitation period of 120 min at 60 °C. Figure 3c shows the leaching efficiencies of U, Cu, and Cd, indicating that the optimal concentration for U is 150 g/L, and the best concentration for Cu and Cd is 200 g/L. Higher concentrations of the indicated mixture (e.g. 250 g/L) had no discernible effect on uranium, copper, or cadmium leaching efficiency.
Effect of alkaline contact time This effect was investigated by mixing the analyzed ore sample with 150 g/L alkaline solution at a S/L ratio of 1/5 at a temperature of 60 °C, stirring from 30 to 240 min. The leaching efficiency as a result Fig. 3d shows that, 3 h leaching duration is ideal for dissolving 85%, 75.8%, and 76.4% U, Cu, and Cd, respectively. Effect of temperature Experiments of leaching are aimed at determining the influence of temperature on the leaching efficiencies of U, Cu, and Cd was investigated at temperatures ranging between 25 and 100 °C, while the other leaching circumstances remained constant Fig. 3e. Uranium, copper, and cadmium leaching efficiency rose as the temperature rose from 30 to 90 °C, with 90% of U, 88% of Cu and 85% of Cd dissolved at 90 °C. After it, there was a sharp drop in leaching efficiency at 100 °C. This decrease can be related to the decomposition of ammonium carbonate at higher temperature [51]. As a result, 90 °C was chosen as the preferred leaching temperature.
Effect of solid/liquid ratio It was chosen to investigate the influence of S/L ratio on the leaching efficiencies of uranium, copper, and Cd from the trial version in a future trial to increase the leaching efficiencies of U, Cu, and Cd from the ore, the consequence of S/L on the efficiency of U, Cu, and Cd leaching was examined between 1/2 and 1/6 and stirring at 180 min and 90 °C, and it was discovered that The efficiency of uranium leaching has grown to 90%, the copper leaching efficiency was 88% and Cd leaching efficiency was 85%. So, it was considered 1/5, Solid/iquid ratio the optimum Fig. 3f. Thus, from alkaline leaching factors of the working ore sample of Talet Seleim, it may be deduced that the optimum leaching conditions for dissolving approximately 90% of U, 88% of Cu and about 85% Cd are as follows: 200 µm particle size, 200 g/L of 4:1 mixed Na 2 CO 3 / (NH 4 )HCO 3 , 3 h leaching time, 1/5 S/L (solid/liquid ratio) at 90 °C.

Results of salt roasting
The impact of several experimental conditions such as roasting temperature, ore/reagent weight and time have been presented and discussed in details. Experiments with NaOH roasting were carried out at various temperatures for roasting (400-900 °C) and times to roast (1-4 h). In all trials, water had leached the roasted cake with a S/L of 1/5, the temperature of leaching was 25 °C, stirring for 2 h.

Effect of roasting temperature
The influence roasting temperature on the working ore sample's leaching efficiency was explored using a series of roasting tests ranging from 400 to 900 oC. The additional roasting parameters were set at a weight ratio of 1/3 ore/NaOH and a roasting time of 2 h. Figure 4a shows that when the temperature of roasting was increased from 400 to 700 °C, the leaching efficiency of U, Cu, and Cd increased to 85%, 80%, and 78% respectively, before dropping to 75%, 70% and 60% at 900 °C. However, the leaching efficiency of U, Cu, and Cd decreased as the roasting temperature went to 900 °C. Roasting at 900 °C causes massively decompositions, generating the lowest leaching percentage due to increasing some undissolved elements [52][53][54]. Effect of roasting time Another set of roasting experiments was carried out to see how roasting time affected the leaching efficiency of the examined metal values, with the roasting temperature set at 700 °C and a 1/3 ore/(NaOH) wt. ratio at various roasting times vary between 1 and 4 h. The obtained results are showed in Fig. 4b. These results show that roasting time has a direct impact on the leaching efficiency of uranium, copper and cadmium with leaching efficiency increasing from 80%, 75%, and 70 to 90%, 89%, and 83% at 3 h, respectively. At 4 h, the metal values' leaching efficiency decreases because roasted ore showed caking, which caused leaching of part elements to become more difficult [55]. Thus, 3 h considered as the best roasting time.
Effect of ore/NaOH weight ratio Mixing the ore with NaOH in various ratios ranging from 1/2 to 1/5 and roasting at 700 °C for 3 h was used to investigate the influence of the ore to reagent weight ratio. The metal values' leaching efficiencies studied are shown in Fig. 4c. It should be obvious from the collected results that S/S ratio1/4 has attained 94%, 92% and 90% for U, Cu and Cd respectively. It is obvious from the preceding statistics that, the optimum salt roasting conditions are as following: Roasting temperature: 700 °C, Roasting time: 3 h, ore/NaOH wt ratio: 1/4.

A comparison between the different leaching techniques
The best leaching conditions for dissolving the interested metal values of Talet Selim ore material for each process were summarized in the following Table 2 based on the foregoing acid agitation leaching, alkaline, and roasting studies. In order to recover the metals of interest, it can be stated that H 2 SO 4 acid agitation leaching is favoured for preparing the pregnant leach liquid. (U, Cu, and Cd) for the following reasons: 1 Using sulfuric acid agitation leaching is preferred to bring out the interested elements into solution in rea-sonable efficiencies. Sulphuric acid is the most favoured leach for recovering uranium from ores because it is affordable, less corrosive, and creates anionic uranyl complex, which enables the subsequent separation of uranium from other cationic gangue minerals using an anionic exchanger simple [44]. 2 Though carbonate leaching which is more selective, it is used mostly for treatment of ores, which contain higher acid consuming carbonate minerals. Kinetics of carbonate leaching is slow and also carbonate does not attack calcareous materials [44]. Agitation leaching with sulfuric acid is more economic compared with alkaline leaching and salt roasting with NaOH. The salt roasting process needed very high temperature to accomplish U, Cu, and Cd selective dissolution. As the temperature rises, the data show that, the rate of U, Cu, and Cd leaching increases. The experimental results in Fig. 5 were connected to obtain the kinetic equation and apparent activation energy for the dissolution of U, Cu, and Cd, researchers applied multiple kinetic models for solid-liquid processes [56]. For spherical particles of constant size, shrinking core models are used to study kinetic leaching.

Kinetic leaching of uranium
The shrinking-core model assumes that the process of leaching is regulated by either the rate of chemical reaction at the surface or a contracting volume kinetic model [57] as Eq. (7), or the Ginstling-Brounstein-Crank model describes diffusion through a solid product layer [58] as Eq. (8), The Jander model is a three-dimensional diffusion kinetics model that may be used to estimate the leaching reaction rate expressions based on statistical analysis of the experimental results. In the literature, Jander equations can be found [59].
where k d and K c are constants of apparent reaction rates (min −1 ) for each example, the leaching time is t (min.), and X is the proportion reacted represent as a percentage.
from the slope of the straight line of the relation between kinetic model and time. Table 3 shows the K d and K c values obtained from Eqs. (7) and (8). The correlation coefficient (R 2 ) values denote the degree of fit between anticipated data and the experimental. The correlation coefficient (R 2 ) for the best fit is around 1.0. The K c values for U, Cu and Cd given in Table 3 the intensity of the rage is 0.0015-0.0041 min −1 , 0.0017-0.0037 and 0.0015-0.0038 respectively, while the K d for U, Cu and Cd were between 0.0008 and 0.0041 min −1 , 0.0009-0.0036 and 0.001-0.0037 respectively. The correlation coefficient (R 2 ) values for K d for U, Cu and Cd were 0.9768-0.8447, 0.9938-0.8377 and 0.963-0.7343 respectively; while the correlation coefficient (R 2 ) values for Kc, for U, Cu and Cd it was in the range of 0.8296-0.5707, 0.822-0.5525 and 0.7831-0.4537 respectively. Based on the correlation coefficient (R 2 ) values it can be inferred that the predominant dissolution mechanism of uranium, copper and cadmium from Talet Seleim ore material is diffusion controlled only.

Calculation of the activation energy
Calculation of activation energy using the Arrhenius formula, the apparent energy of activation was calculated as previously mentioned in Eqs. (9,10) [60].
where A stands for the frequency factor, K is the constant of reaction rate, E a represents the apparent energy of activation, and the universal gas constant is denoted by R g . The apparent activation energy (E a ) was calculated from the slope of straight line. From Fig. 8 The activation energy (E a ) was calculated as follow Eq. (11).
In general, the activation energy of a chemical reaction is larger than 40 kJ/mol, whereas the activation energy of a diffusional process is less than 20 kJ/mol, and The activation energy of a mixed regulated regime is estimated to be between 40 and 20 kJ/mol [61]. As a result, the calculated apparent activation energy (E a ) For reaction rate expression controlled by the diffusion for U, Cu and Cd was determined to be 29.59 kJ/mol, 29.30 kJ/mol and 34.84 kJ/mol respectively. Therefore the obtained value of apparent activation energy suggests a possible diffusion reaction controlled in

Recovery of interesting metal values
To recover U, Cu, and Cd from Talet Seleim's Gibbsite ore sample, an appropriate 4 L leach liquor was made from 1 kg of the working ore sample using the previously estimated optimum leaching conditions. This resulted in 0.144, 0.338 and 0.045 g/L within leaching efficiencies for U, Cu and Cd respectively.

Uranium recovery
In a Pyrex glass column with a radius of 0.5 cm, a resin sample of Amberlite IRA 400 corresponding to 8.5 mL wet settled resin (w s r) was packed over a glass wool plug. The pH of the prepared 4000 ml acid leach liquor was adjusted to 1.8 because iron ions are significantly adsorbed when the pH of the pregnant solution exceeds pH 1.8, whereas HSO 4 − is strongly adsorbed below this value [63]. This liquor was then passed through the prepared resin column bed at a flow rate of about 1.9 mL/min, the effluent sample was collected every 200 mL and analyzed for Uranium. According to the theoretical capacity of Amberlite IRA400 would amount to 1.56 meq/mL resin, the adsorption capacity of uranium would amount to 91 mg uranium/ml resin if the adsorbed species is [UO 2 (SO 4 ) 3 ] 4− .

Uranium elution
The resin column was first washed with distilled water to remove the pregnant solution before to uranium elution. Following that, the eluant solution of 1 N NaCl acidified with 0.25 M sulfuric acid was passed at a flowrate of 1.6 mL/min, and the resulting eluate was collected every 10 mL for uranium analyses. The elution efficiency for U was determined to be 96.4%. Uranium was precipitated in the form of ammonium diuranate from the collected eluate at a pH of roughly 5.5 using a 30% NH 4 OH solution as the following Eq. (12) The product was subjected to analysis using ESEM-EDX Fig. 9a. Chemically, it has about 80% U 3 O 8 after calcination at 850 °C.

Recovery of copper
Cu hydroxide crystals were obtained from uranium effluent liquor by adjusting its pH to 5.5 using ammonia solution (

Recovery of Cd
The prepared sulfate solution preprocessed with Na 2 S solution and free from U and Cu 2+ and its pH value rose up to pH 0.38. The latter was first treated with a 5% NaOH solution (13) Cu 2+ (aq) + 2NH 3 (aq) + 3H 2 O → Cu(OH) 2 (s) + 2NH + 4 (aq) to get its pH down to 0.5, and then with 0.25% Na 2 S in a 1/1 volume ratio. About 99.5% of Cd 2+ ions were preferentially precipitated as a mixed cake (CdS + S metal) after 30 min of stirring at room temperature. The following Eqs. (14)(15)(16)(17) illustrates the precipitation process [21,34]: (14) Cd SO 4 + Na 2 S → (CdS + S elemental) cake + Na 2 SO 4 (15) (S + CdS) cake + HNO 3 → Cd NO 3 2 + S metal (16) Cd NO 3 2 + 2NaOH → Cd(OH) 2 + 2NaNO 3 (17) Cd(OH) 2 ignited The precipitated (CdS + S) cake was then dissolved in 100 mL of 5% HNO 3 solution where CdS was completely dissolved at room temperature leaving behind elemental S. On the other hand, the prepared Cd(NO 3 ) 2 solution was then treated with 5%NaOH solution and stirring for 1 h at room temperature and left to precipitate Cd(OH) 2 . Complete precipitation of Cd +2 ions takes place at pH: 8.5. The produced Cd(OH) 2 cake was then carefully washed with distilled H 2 O to remove any adsorbed contaminates and then ignited at 750 °C for 1 h to produce CdO. The latter was washed, dried and then directed to ESEM-EDX analysis for identification, chemically it has about 95% Cd Fig. 9c.

Proposed flow sheet
Based on the obtained results, a flow sheet, Fig. 10 is proposed for recovery of the metal values (uranium, copper, and cadmium) from the Gibbsite ore material at Talet Seleim using sulfuric acid.

Conclusion
A comparative study was carried out between acid, alkaline and salt roasting leaching for U, Cu and Cd from Talet Seleim, southwestern Sinai, Egypt technical sample. Many leaching factors include, leaching solution concentration, solid/liquid ratio, temperature, and reaction time were studied and optimized. With reference to this study and the data examples, it is possible to determine what the ideal conditions are for each approach: • The optimum agitation acid leaching for leaching 95%, 90% and 89% of U, Cu and Cd respectively would be concluded as follow: 200 µm particle size, 200 g/L acid concentration, leaching time 180 min.at 80 °C and stirring speed 500 rpm/min. • The optimum alkaline conditions for leaching 90%, 88%, 85% of U, Cu and Cd respectively was 200 µm particle size, 200 g/L of 4:1 mixed Na 2 CO 3 /(NH 4 )H CO 3 , time: 3 h, S/L ratio: 1/5 and temperature: 90 °C. • The optimum salt roasting conditions for leaching 94% U, 92% Cu and 90% Cd were: 200 µm particle size, roasting temp: 700 °C, roasting time: 3 h, Ore/(NaOH) wt ratio: 1/4.
The most preferred leach for extracting uranium from ores is sulphuric acid because it is less expensive, less corrosive, and produces anionic uranyl complex, which subsequently allows the separation of uranium and valuable metal from other cationic gangue minerals using a simple anionic exchanger. The rate of dissolution of U, Cu, and Cd in sulfuric acid leaching diffusion was regulated and follows core model of shrinking [1-3 (1−X) 2/3 + 2 (1−X)] = k d with apparent activation energies of 33.48 kJ/mol, 29.23 kJ/ mol, and 33.34 kJ/mol, respectively. Recovery of the leached metal values was performed by using Amberlite IRA 400 anion exchange resin for U and direct precipitation for Cu and Cd. Finally, a flowsheet was created using the collected data.
Funding Open access funding provided by The Science, Technology & Innovation Funding Authority (STDF) in cooperation with The Egyptian Knowledge Bank (EKB).

Conflict of interest
The author declare that they have no conflicts of interest.
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