Processed ores may contain substantial amounts of residual valuable metals. In the case of the mining wastes issued from the exploitation of gibbsite bearing shale ore in the Southwestern Sinai, the characterization of the residue shows the presence of uranium, rare-earth elements (REEs), aluminum and zinc that can be valorized. Pug leaching at 120°C with an acid consumption of about 200 kg H 2 SO 4 per ton of ore succeeded in leaching more than 94% of U(VI) and REEs (in addition to substantial amounts of Al(III) and Zn(II)). A series of selective precipitation steps allowed successively recovering (almost quantitatively) Zn(II), Fe(III) and Al(III). In a second step, a magnetic resin has been used for enriching the pregnant leaching solution (by a factor close to 19) through sorption/desorption steps. In the last stage of the process, REEs were recovered by selective precipitation using 25% (w/w) oxalate solution at pH 1.5, while uranium was fully recovered by precipitation with NaOH at pH 9. Energy dispersive X-ray analysis performed on the different precipitates showed purity grades systematically superior to 93%.

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Variable single and/or swarms of post-granitic dikes are widespread at Gabal Serbal, Southwestern Sinai, Egypt. The present article aims to identify and discriminate these multiphase dikes through detailed geological, petrographical, and geochemical examinations. These dikes are classified into two subphases: (1) acidic dikes (porphyritic dacite, microgranite, granophyre, and alkaline granophyre dikes); and (2) basic dikes (basalt and dolerite dikes). They range from vertical or steeply inclined bodies, 0.5–15 m wide, pink to black color, and NE–SW to N–S directions. Acidic dikes with different mineralogical constituents have medium to high k-characters, originating from calc-alkaline magma and extruded in a volcanic arc environment. In contrast, basic dikes have medium k-characters, originating from tholeiitic magma and developing within a plate environment. Basic dikes are enriched with opaque minerals, where the basaltic dike contains iron oxides (magnetite and hematite), such as apatite in addition to copper minerals. Dolerite dike comprises magnetite, titanomagnetite, and pyrite.

High-level natural radioactivity, geochemical, geological, and radiological hazard assessment of the poorly investigated Wadi Gebeiy Dokhan volcanics rocks are discussed. Wadi Gebeiy Dokhan volcanics are located in Southwestern Sinai, Egypt, covering an area of ~1.3 km2. Dokhan volcanics rocks are represented by porphyritic dacite. Geochemically, they have medium-k characters and originate from calc-alkaline magma within a volcanics arc environment. Along the fault plane striking NNE-SSW, and at its intersection with the NW-SE fault plane, altered Dokhan volcanics occur with high radioactive anomalies. Radiological parameters (absorbed dose rate, radium equivalent, activity annual effective dose, external and internal hazard indices) are used to evaluate their suitability as an ornamental stone. Except for the absorbed dose rate, all the radiological hazard indices show that unaltered Dokhan volcanics can be used as an ornamental stone. Controversially, the applied radiological indices reveal that altered Dokhan volcanics have a higher content than the recommended values of UNSCEAR, reflecting their risk on human organs.

The search of novel strains continues to be of great importance in research around the world for pharmaceutical, industrial, agricultural and biomining applications. The present study aims to investigating the microbial diversity of rock samples collected from Um Bogma formation, southwestern Sinai, Egypt which was chosen for its unique location, geological and physicochemical properties. The studied samples showed small microbial diversity and low microbial count. A total of ten isolates of actinobacteria and ten isolates of fungi were isolated and characterized phenotypically. The results indicated that all the isolated actinobacteria belong to the genus Streptomyces. They were all halotolerant with some showing antimicrobial activities when tested against Bacillus subtilis, Pseudomonas aeruginosa ATCC 9027, Staphylococcus aureus ATCC 6538, Escherichia coli ATCC 8739, Candida albicans and Aspergillus flavus. On the other hand, all the studied fungal isolates belong to the genus Aspergillus. They showed resistance to the antifungal nystatin when a concentration of 50 µg per ml was used. The studied locations is characterized by their harsh conditions which does not support the growth of most microorganisms which includes a temperature ranging from below 0°C at night to above 46°C throughout the day, low water content and organic matter hosting radioactive and heavy elements. Rock-dwelling microbial communities that survived such conditions open further

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Samples of gibbsite bearing-shale of south western Sinai, Egypt were studied to upgrade the low grade alumina. The assays of the samples are about 18.98% Al 2 O 3, 15.45% SiO 2, 12.83% Fe 2 O 3 , 14.87% CaO, 5.74% P 2 O 5 , 5.34% MnO, 0.86% K 2 O, 0.76% Na 2 O, 1.50% trace elements and 23.65% loss on ignition. The aim of upgrading alumina in the concentrate is to make it suitable for the different industrial uses. Sodium dodecyl sulfate (an anionic collector) is effective in the acidic pH range. Below the isoelectric point of gibbsite where the alumina is positively charged, the sodium dodecyl sulfate was good at pH value of 2. Under appropriate conditions (collector dosage=800g/t, pulp density=300g/l and particle size=-100+80 µm) and at pH=2, a concentrate containing 39.5% alumina at component recovery of 96.9% and mass recovery of 52.8% was obtained. At these conditions, the assays of other ore constituents in the final concentrate are as follows: SiO 2 was decreased from 14.2% to 6.4%, CaO was decreased from 14.1% to 5.2%, Fe 2 O 3 was decreased from 13.1% to 5.6%, P 2 O 5 was decreased from 4.3% to 3.8%, MnO was decreased from 4.2% to 3.2%, while K 2 O was increased from 0.89% to 1.2%, Na 2 O was increased from 0.69% to 1.1%, traces was increased from 1.6% to 2.6%, and loss on ignition was increased from 25.4% to 31.2%. The component recoveries of SiO 2, CaO,