Journal of King Abdulaziz University: Engineering Sciences

Extraction of Rare Earth Elements (REEs) from coal ash of Thar, Pakistan by chemical leaching with Novel Deep Eutectic solvents

2024-10-29T04:39:31+00:00

The supply of rare earth elements is less and its demand is high so we need a secondary source to fulfill this demand. This research adopted coal ash as an alternative resource of rare earth elements. The mineral acids, ionic liquids, and organic acids were used for the extraction of rare earth elements (REEs) from Coal Ash (CA) which were corrosive, expensive, hazardous, and not friendly to the environment. Our approach was to find innovative reagents that were green to the environment and extract REEs from CA as a replacement for mineral acids, ionic liquids, and organic acids. The researchers synthesized a novel Deep Eutectic Solvent (Choline chloride & Humic acid) for the extraction of REEs. The study conducted experiments on the coal of Sindh Engro Thar Coal Mining Company (SECMC), Pakistan. Based on literature and ASTM standard D-2013 coal was crushed and ground to a size of -250 microns. The leaching experiments were designed with two different parameters (1-2 hours) time and temperature (60-90 Celsius) at a constant 500 revolutions per minute (rpm). After leaching, the filtrate was centrifuged at 4000 rpm for 10 minutes. Both the feed and leachate were analyzed using various techniques, X-Ray fluorescence (XRF), X-Ray Diffraction (XRD), Inductively coupled plasma mass spectrometry (ICP-MS), Fourier Transform Infrared Spectroscopy (FTIR), and Scanning Electronic Microscope (SEM). In feed characterization, the XRF results showed that Calcium had the highest percentage which was 35.676%. Calcium sulfate, Diborane, and Magnesium oxide mineral phases were detected by XRD. ICPMS analysis showed the CA sample contained a total of 351.41 PPM of REEs. The concentration of heavy rare earth elements (HREEs) were 119.5 PPM, while the light rare earth elements (LREEs) were 231.91 PPM. Moreover, Lutetium had a PPM value of 96.56 and was the most prevalent REE. In FTIR spectroscopy C, C=O, C-H bond, C-O-C, N-O bond, and SiO functional groups were found. In SEM analysis, luminous and non-luminous features could be seen in the matrix which indicates the presence of minerals by raw CA sample while both luminous and non-luminous features were disseminated in CA dipped with DES sample. The leaching efficiency of the DES was increased by increasing the temperature and time. The highest leaching efficiency we achieved was at 90 degrees Celsius for 2 hours which was 90%, While, at 60 degrees Celsius for 1 hour the DES was at its lower peak and the efficiency was 62%. Our results showed that the DES was effective in extracting REEs from CA.

Colorectal Secondary Malignancy Risk Estimates Following Radiation Therapy: A Prospective Cohort Study Among Cancer Survivors In Saudi Arabia

2024-10-03T10:16:13+00:00

Radiation-induced second cancer is one of the crucial late side effects of radiotherapy treatment of first cancer. Although the second cancer induction mechanism is not well understood yet, many factors are related to its occurrence, such as age at exposure, dose to the organ and surrounding tissues, treatment modalities, and family history of cancer. This study aims to provide long-term estimates of second cancer incidence amongst colon cancer survivors in Saudi Arabia. The lifetime attributable risk (LAR) after radiation treatment of colon cancer was determined, between the age at exposure and up to 95 years, in a single-institution cohort of male and female cancer survivors whose age at treatment was in the range of 43 to 85 years. Risk estimates varied significantly with age at exposure, gender, and organ dose.

A Method to Replace Section with other sections with capacity Equal Tolerance in the case of spandex and flexible

2024-10-10T12:18:11+00:00

Construction Engineers face difficulties during the execution of metallic construction works that compose standard Profiles or designer in other countries where the designer prescribes profiles which are not common in local area .

This will causes sustention of construction works and consequently material and lasses. Those engineers may need a method for replacing these profiles with others.

In this research, Author describes a novel method that enables designers to replace supposed metallic profiles Sections (e.g. solid Rectangular, ring section) with new Sections (Box, [ and I sections) provided that the moment of Inertia of the new section equals the moment assuming that the elastic theory is used. In Case the Plastic theory is used, the condition will be the static moment of the new section is equal to static moment of original section. The author evaluated the research results.

Modeling and optimizing electro Fenton process for silica removal to prevent RO membrane fouling in brackish water desalination.

2024-10-17T07:32:39+00:00

Due to high silica concentrations, silica scaling of reverse osmosis (RO) membranes in brackish water desalination poses very serious issues in the cost-effectiveness of desalination processes. The advanced Fenton process (AFP) is one of the most effective water treatment processes. Coagulation of silica on ferric hydroxide and flocculation are the main processes used to remove silica. This process depends on several operating parameters such as hydrogen peroxide and zero-valent metal iron Fe⁰ dosage, initial and equilibrium pH. In this study, we examined the use of Artificial Neural Networks (ANNs) to optimize those parameters using an experimental dataset. For a removal of 71.3%, the optimum operating parameters were: initial pH 2, equilibrium pH 8, iron dosage 15 g/L and hydrogen peroxide 18 mM. We show that the environmentally friendly Fenton process was economically feasible, being able to attain up to 71.2% silica removal with a total cost of $2.09 m^-3 for a typical desilication unit producing 1,000 m³/day.

Effect of thermal treatment on magnesite impurity removal using dry high-intensity magnetic separation

2024-10-30T12:17:57+00:00

This study investigates the extraction of impurities from a low-grade Saudi magnesite ore with the following composition: 37.68% MgO, 7.24% CaO, 3.10% SiO₂, 1.91% Fe₂O₃, 0.58% Al₂O₃, and 48.65% LOI. Additionally, it examines the calcination process of magnesite and the subsequent removal of impurities. Dry high-intensity magnetic separation was utilized for the magnesite both before and after calcination. Various parameters, including feed size, feed rate, magnetic field strength, and roll speed, were assessed using an Outotec-induced roll magnetic separator (model MIH 13 111-5). The results demonstrate that impurity removal and recovery are more efficient after calcination than before. The final product is anticipated to be a suitable raw material for producing dead-burned magnesia, which is utilized in the refractory industry.

Continuous Cash Flow Modeling for Economic Evaluation and Risk Analysis in Mine Planning Using Monte Carlo Simulation

2024-10-29T15:54:10+00:00

The discrete cash flow (DCF) model is usually used to estimate the net present value (NPV) of most projects. However, the model produces results that could be short of reality, especially for projects with high uncertainties that last for decades, as in mining projects. Hence, this paper develops a Continuous Cash Flow (CCF) model for the economic evaluation of mining projects. The model is used for the economic feasibility of a gold mine project in Saudi Arabia. The dynamic DCF model is also used for the same project and obtained results from both models were simulated using the Monte Carlo technique. Results show that the CCF model produces lower NPV values than the DCF. The developed model could be an alternative approach to determining the expected NPV in mine projects.