Papers by Keyword: Red Mud

Abstract: Red mud, a by-product of the aluminum industry, poses a threat to the environment with its high alkalinity and heavy metal content and may seep into the soil and groundwater, endangering ecology and health. Effective utilization of red mud can reduce pollution and achieve resource recycling. In this study, a metakaolin/red mud geopolymer was prepared by phosphoric acid excitation to investigate its adsorption capacity for lead ions. The ratio of metakaolin to red mud and the additions of phosphoric acid and water were optimized, and the optimal formulations were 3/7 mass ratio of metakaolin to red mud, 2.2 molar ratio of H₃PO₄/Al₂O₃, and 0.5 water-solid ratio, which demonstrated good stability and operability.

Abstract: Red mud may cause serious pollution to soil, water, and air. Lead can seriously harm biological and even human health. This chapter summarizes the adsorption properties of metakaolin/red mud base polymer for Pb (Ⅱ). Under optimized conditions, with 0.6g/L adsorbent, pH value of 5, and adsorption time of 120 minutes, the adsorption capacity reached 122.58mg/g, and the removal rate was 73.55%. This will help to mitigate the threat of red mud and lead wastewater to human health and the environment, providing an important reference for water pollution control.

Abstract: The development of composites with the waste of industries close to each other would mean an interesting case of industrial symbiosis in search for using less financial and natural resources. This paper presents the development of polymer composites made of three types of waste, produced by industries located in the same region and distant at most 25 km from each other: electronic waste, red mud (obtained during aluminium production), and the waste of wind turbine blades' manufacturing (epoxy resin/glass fibre). Composites were obtained incorporating 5%, 10%, and 15% of industrial waste (red mud and epoxy/fibre) in a matrix of recycled high-impact polystyrene (HIPS) from discarded electronic equipment. Tests were performed to obtain the melt flow index and the composites' water content and study the mechanical properties (tensile and impact) of test specimens produced with the composites by injection moulding (temperature from 200 to 250°C, the injection pressure of 45 MPa, and the injection time of 2.5 s). Results showed that the composites have water content and melt flow index within the specifications for recycled HIPS and are usually more rigid than it, reaching values for Elasticity Modulus up to 34% higher. Therefore, these composites can be applied when materials with more stiffness than HIPS are required.

Abstract: This study continues and develops approaching of bauxite residue treatment and associated waste for extracting highly valuable metals and scandium recovery by optimizing a hydrometallurgy method for process intensification. Laboratory-scale experiments were conducted in a nitric acid medium on electrostatic precipitator dust (ESPD) received in bauxite sintering. The method includes prior water-leaching of ESPD and subsequent asid leaching experiments at different liquid-to-solid ratios, leaching times and temperatures. The maximum extraction of the scandium was around 76.5 % at pH=0.2. Experimental design based on response surface methodology was used for obtained values optimization. Researches have shown that the optimization of the conditions for the transfer of scandium from red mud to the leaching solution mainly depends on the pH that have to be adjusted in range 0.5-1.7. The pH should not be too low, since Sc does not have time to go into solution in the presence of iron and other elements, as well as too high, because high values lead to re-precipitation of Sc from the filtrate. Complete study for Sc recovery is under progress and is not elaborated here.

Abstract: The article focuses on the main mathematical modeling principles for engineering processes. The physical model of the red mud thickening process has been formed. The choice of mathematical model type has been described where the mathematical model represents the physicochemical character of the thickening process and allows estimating pulp water-yielding features at the stage of compression. Mathematical modeling of the engineering process, based on the studies of physicochemical patterns in its course and consideration of these patterns in the mathematical model, does not have certain disadvantages. Experimental data, used at the mathematical model formation where the mathematical model represents the physicochemical mechanism of the process, serve for their further analysis, physicochemical and mathematical interpretation. The mathematical model should be used as a method for detecting internal patterns in the process and for identification and quantitative assessment of its features.

Abstract: Current global environmental challenges and, above all, global warming associated with a change in the carbon balance in the atmosphere has led to the need for urgent and rapid search for ways to reduce greenhouse gas emissions into the atmosphere, which primarily include carbon dioxide as a by-product of human activity and technological progress. One of these ways is the creation of industries with a complete cycle of turnover of carbon dioxide. Aluminum is the most sought-after nonferrous metal in the world, but its production is not environmentally safe, so it constantly requires the development of knowledge-intensive technologies to improve the technological process of cleaning and disposal of production waste, primarily harmful emissions into the atmosphere. Another environmental problem related to aluminum production is the formation and accumulation in mud lagoon of huge amounts of so-called highly alkaline "red mud," which is a waste product of natural bauxite raw material processing into alumina - the feedstock for aluminum production. Commonly known resources and technological methods of neutralizing red mud and working with it as ore materials for further extraction of useful components are still not used because of their low productivity and cost-effectiveness. This article describes the negative impact of waste in the form of "red" mud and carbon dioxide of primary aluminum production on the environment. The results showed that thanks to carbonization of red mud using carbon dioxide, it is possible to achieve rapid curing and its compact formation for safer transportation and storage until further use. Strength tests of concrete samples filled with deactivated red mud were also carried out, which showed the prospects of using concrete with magnesia binder.

Abstract: Dimethyl ether (DME) is apromising alternative for substituting petroleum fuel including gasoline, liquified petroleum gas, and diesel. In this research, the utilization of red mud as catalyst was investigated to dehydrate methanol to Dimethyl Ether (DME). Red mud is a solid waste from the bauxite industry which lead to environmental issues if did not treat properly. The catalyst characteristics were determined in terms of porosity, crystallinity, elemental composition, and pores size distribution. The catalysts activity was evaluated in a fixed-bed reactor at temperature range 200-300 °C. The influence of different parameters, including temperature and type of catalyst were varied to obtain the optimum reaction condition. The results revealed that the highest methanol conversion was 68% at temperature of 300 °C when using calcined red mud catalyst.

Abstract: In Russia, the main feedstock for producing aluminum is bauxite. During the processing of 1 ton of bauxite into alumina (Al₂O₃), up to 0.5–0.6 ton of techno-genic waste is formed, that is red mud. It is not currently disposed of and accumulated in mud tailing dumps. It contains valuable components: Al – 8 %; Fe – 25 %; Ti – 2.4 % and it can be considered as a potential raw material for ferrous metallurgy and as a source of vanadium, titanium, and rare-earth elements (REE) Sc, Y, La. The paper shows the possibility of obtaining red mud with an increased iron content of up to 36 %, with an additional extraction of aluminum. Red mud from the Ural Aluminum Plant (Russia) is considered. It is proposed to direct this mud to the production of pellets for the production of cast iron. To extract aluminum from red mud, it is proposed to process the mud in a highly alkaline medium by sintering in the temperature range 300–600 °C. The resulting sinter is leached with water or a slightly alkaline solution with the conversion of aluminum compounds into solution. The red mud, obtained this way, exhibits magnetic properties. A magnetic separation was carried out, and the yield of the magnetic fraction is 79.87 %. The iron content increases by 25 % and amounts to 51.88 % of Fe₂O₃.

Abstract: The article analyses the application of a composite material based on magnesite cement and red mud for the production of high-resistant materials and structures. Technical characteristics are given proving that this composite has several advantages comparing with other materials and opens up new opportunities for the disposal of toxic wastes and developing new materials with unique characteristics. The advantage of this direction is that the composite material created on the basis of “red mud” has increased strength and water resistance; also, it has the structure of a homogeneous monolithic stone. A wide range of applications of neutralized waste is an undeniable positive factor.

Abstract: The problem associated with biodiesel production is economic feasibility. The biodiesel cost will reduce when the low cost feedstock was used as feedstock. Used Cooking Oil (UCO) is a promising candidate as raw material for biodiesel synthesis. In this study, the investigation of biodiesel synthesis from UCO was studied using red mud as heterogeneous catalysts. The catalyst was prepared by impregnating Potassium metals on red mud. The catalyst physico-characteristics were determined using Nitrogen gas adsorption, FT-IR, XRD, and XRF. The catalyst was tested to synthesize biodiesel from UCO. The reaction temperatures, methanol to oil mass ratio, and amount of catalyst were varied to examine their effects on biodiesel synthesis. The optimum reaction conditions were obtained at 60°C of reaction temperature, 10:1 of methanol to oil mass ratio, and 10% of catalyst amount. The highest biodiesel yield of 94.4% was obtained.