Mathematical Modelling for Furnace Design Refining Molten Aluminum

The design of an aluminium melting furnace has faced two challenges: mathematical modelling and simulative optimization. This paper first uses fluid dynamics to model the aluminium process mathematically. Then, the model is utilized to simulate a round shaped reverberatory furnace for melting aluminium alloys. In order to achieve the highest thermal efficiency of the furnace, modelling and simulation are performed to predict complex flow patterns, geometries, temperature profiles of the mixture-gas air through the main chamber, as well as the melting tower attached to the furnace. The results led to the establishment of optimal position and angle of the burner, which are validated through physical experiments, ensuring recirculation of the combustion gases through the melting chamber and the melting tower. Furthermore, a proper arrangement of refractory materials is derived to avoid heat losses through the outer surface of the furnace. Temperature profiles are also determined for the optimization to arrive at the final design of the furnace. Compared with manual designs previously practiced, the simulation-based optimal design of furnaces offers excellent guidance, an increase in the aluminium processing and magnesium removal for more refined alloys, and an increased processing rate of aluminium chip accession.

An Experimental Approach to Assessing the Roles of Magnesium, Calcium, and Carbonate Ratios in Marine Carbonates

Marine biomineralization is a globally important biological and geochemical process. Understanding the mechanisms controlling the precipitation of calcium carbonate [CaCO3] within the calcifying fluid of marine organisms, such as corals, crustose coralline algae, and foraminifera, presents one of the most elusive, yet relevant areas of biomineralization research, due to the often-impenetrable ability to measure the process in situ. The precipitation of CaCO3 is assumed to be largely controlled by the saturation state [Ω] of the extracellular calcifying fluid. In this study, we mimicked the typical pH and Ω known for the calcifying fluid in corals, while varying the magnesium, calcium, and carbonate concentrations in six chemo-static growth experiments, thereby mimicking various dissolved inorganic carbon concentration mechanisms and ionic movement into the extracellular calcifying fluid. Reduced mineralization and varied CaCO3 morphologies highlight the inhibiting effect of magnesium regardless of pH and Ω and suggests the importance of strong magnesium removal or calcium concentration mechanisms. In respect to ocean acidification studies, this could allow an explanation for why specific marine calcifiers respond differently to lower saturation states.

The removal of Mg2+ and Ca2+ and turbidity from aqueous solution employing copolymerization of ethyl acrylate onto guar gum

Acid mine drainage collected from decant in Krugersdorp, South Africa, was treated in a series of laboratory experiments using synthesized copolymer of guar gum-g-polymer (GG) for the removal of calcium and magnesium and turbidity. 250 mL of sample and 25 mL distilled water were added into 16 Erlenmeyer flasks. The samples were irradiated in a micro-oven at 900 W for 3 min and the mixtures were placed in a soxhlet extractor for homopolymerization, after which they were dried and crushed. The results showed an exponential increasing adsorption efficiency of calcium removal with increasing pH range 2–4, and a slight increase between the pH range 4–8. On the other hand, the results showed a continuous increasing adsorption removal efficiency of magnesium with increasing pH in a range 2–8. The results showed a slight increasing adsorption efficiency of calcium removal with increasing dosage between 15 and 25 mg/L of GG, an exponential increase between 15 and 35 mg/L and resuming a slight increase between 45 and 55 mg/L dosage. On the other hand, the results showed an exponential increasing adsorption efficiency of magnesium removal between 15 and 54 mg/L dosage and slight increasing trend between 45 and 55 mg/L dosage.

Insights into Kinetics of Magnesium Removal by Titain Yellow Supported on Classic Thiourea-Formaldehyde Resin

<p>It was evaluated for the adsorption behavior and the underlying kinetics of magnesium sorption on Titian yellow (TY) supported on thiourea-formaldehyde resin (TF). The results of analyzing sorption behavior showed that the sorption environment had different effects on the sorption of Mg(II) ions. It could be found that pH had the best sorption effect on Mg(II) ions, The maximum adsorption capacity of Mg was 19.45 mg g⁻¹ when it was at initial pH = 10.5. Under the optimal conditions, the maximum sorption capacities of Mg(II) ions was 19.45 mg g⁻¹. Therefore, TF-TY was found to be a most efficient adsorbent for Mg(II) removal from water.</p>

Insights into Kinetics of Magnesium Removal by Titain Yellow Supported on Classic Thiourea-Formaldehyde Resin

<p>It was evaluated for the adsorption behavior and the underlying kinetics of magnesium sorption on Titian yellow (TY) supported on thiourea-formaldehyde resin (TF). The results of analyzing sorption behavior showed that the sorption environment had different effects on the sorption of Mg(II) ions. It could be found that pH had the best sorption effect on Mg(II) ions, The maximum adsorption capacity of Mg was 19.45 mg g⁻¹ when it was at initial pH = 10.5. Under the optimal conditions, the maximum sorption capacities of Mg(II) ions was 19.45 mg g⁻¹. Therefore, TF-TY was found to be a most efficient adsorbent for Mg(II) removal from water.</p>

Reducing the Magnesium Content from Seawater to Improve Tailing Flocculation: Description by Population Balance Models

Experimental assays and mathematical models, through population balance models (PBM), were used to characterize the particle aggregation of mining tailings flocculated in seawater. Three systems were considered for preparation of the slurries: i) Seawater at natural pH (pH 7.4), ii) seawater at pH 11, and iii) treated seawater at pH 11. The treated seawater had a reduced magnesium content in order to avoid the formation of solid complexes, which damage the concentration operations. For this, the pH of seawater was raised with lime before being used in the process—generating solid precipitates of magnesium that were removed by vacuum filtration. The mean size of the aggregates were represented by the mean chord length obtained with the Focused beam reflectance measurement (FBRM) technique, and their descriptions, obtained by the PBM, showed an aggregation and a breakage kernel had evolved. The fractal dimension and permeability were included in the model in order to improve the representation of the irregular structure of the aggregates. Then, five parameters were optimized: Three for the aggregation kernel and two for the breakage kernel. The results show that raising the pH from 8 to 11 was severely detrimental to the flocculation performance. Nevertheless, for pH 11, the aggregates slightly exceeded 100 µm, causing undesirable behaviour during the thickening operations. Interestingly, magnesium removal provided a suitable environment to perform the tailings flocculation at alkaline pH, making aggregates with sizes that exceeded 300 µm. Only the fractal dimension changed between pH 8 and treated seawater at pH 11—as reflected in the permeability outcomes. The PBM fitted well with the experimental data, and the parameters showed that the aggregation kernel was dominant at all-polymer dosages. The descriptive capacity of the model might have been utilized as a support in practical decisions regarding the best-operating requirements in the flocculation of copper tailings and water clarification.

Magnesium removal from phosphoric acid by precipitation: Optimization by experimental design

High content magnesium in phosphate and phosphoric acid affect negatively the performance and operating condition in phosphate industry. While for a content more than 0, 3% in phosphate increase the P2O5 losses during phosphate digestion and filtration, also increase steam consumption and solid settling kinetics during concentration. In this work, the removal of magnesium from phosphoric acid by precipitation in one of the compounds MgAlF5 or MgAl2F8 was studied. Magnesium precipitation is achieved by the simultaneous addition of aluminum and fluorine. The experimental design methodology was used to carry out this work. Tests were conducted according to the NEMRODW software using industrial quality phosphoric acid. The screening study of parameters affecting the removal efficiency of magnesium from industrial wet phosphoric acid showed that from the following parameters: temperature, F/Mg and Al/Mg ratios, aluminum form and fluorine form, only temperature and F/Mg ratio have an effective influence on magnesium removal. The optimization of magnesium removal from phosphoric acid was performed according to the response surface methodology using a composite matrix. By applying this methodology, the optimum parameters corresponding to a maximum magnesium removal efficiency in phosphoric acid were determined. The values of the optimum parameters obtained by this method are T?=80?C, ratio Al/Mg=1 and F/Mg= 16.