Modeling and Box-Behnken design optimization of microwave treatment of sulphidic gold flotation tailing

As raw minerals become scarcer every passing day, the need for the recovery of mine tailings becomes essential. This research highlights the use of microwave energy as a green alternative to otherwise environmentally harmful methods of ore tailing recovery. The obtained results indicate that a 1.4 ppm Au and 3.5 % S sample floated with Aeroflot 208 and Aerophine 3418A increased the concentration of tailings over 18 % S and 4 ppm, Au, for recovery yield, resulting in 84 % and 80 % recovery, respectively. After microwave irradiation, 90 % of sulphur removal was reached under the optimum conditions of 50 minutes of irradiation using 1000 W for 4 g of the sample. Overall with 96. 74 % correlation of the quadratic model using the Box-Behnken design and expressed coefficient R2 regression the model was proven to be suitable for heating and roasting processes of gold-bearing tailings

Recent sustainable trends for e-waste bioleaching

For the past few decades, the electronic and electrical waste have been accumulating and piling on our lands and aside from posing some serious threat on our environment and our health. And with the technological advance and the rapid growing electronic demand and production there is the risk of accumulating even more unused valuable usable materials in our waste land-fields. Up to 2030, EU is forecasting about 74 million tons of e-waste, including washing machines, tablet computers, toasters, and cell phones. In 2022, more than 5.3 billion mobile phones were wasted whereas Li, Mn, Cu, Ni, and various rare-earth elements (like Nd, Eu and Tb, etc.) as well as graphite are actually found in the contents of many metal parts from wiring, batteries to their components. The main purpose aside from an environmental aspect is reserving the mineral used in this waste, as many of the crucial materials have a supply risk heavily depending on import. For instance, many of these rare earth elements (REE) are sourced from China; these REEs are used in many electronics that range from consumer products to industrial-use machines. This study is to review one of the desired methods that is via using bio-techniques to dissolve and recover as much as possible from main e-waste sources such as PCBs, spend batteries and LCD/LED panels. Microorganisms that are used for bioleaching process and their metal recovery aspects were compared in the second part. Future perspectives were finally added considering significant techno-economic environmental and social impacts

Rheological, Electrokinetic, and Morphological Characterization of Alginate-Bentonite Biocomposites

We prepared biocomposite gel dispersions involving sodium alginate (Na-Alg) and calcium bentonite (Ca-B) with various solid concentrations and characterized their rheological, electrokinetic, and morphological properties. The flow properties, such as the apparent and plastic viscosities, shear stress, and yield value point, changed with increasing clay dosage. The viscosities of the homogeneous dispersions were represented by the Herschel-Bulkley model. The zeta-potential results were examined in the light of different characterization methods (X-ray diffraction, Fourier transform infrared spectroscopy, and atomic force microscopy) to understand the interactions between the Na and Ca ions of the alginate biopolymer and bentonite clay. A plausible structural model for the alginate-bentonite composite gel, known as the egg-box model, is proposed. The presence of Ca ions in the Ca-B partially crosslinked Na-Alg may be regarded as an excellent example of a self-assembling process. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 122: 19-28, 201