In this study, feasibility of using seawater to neutralize alkaline Red mud for its safe disposal has been studied using Taguchi’s design of experimental methodology. Parameters such as weight of Red mud, volume of seawater, stirring time and temperature were tested at three levels to study their effect on response characteristic, i.e., pH of the neutralized slurry. The analysis of variance showed that volume of seawater added and quantity of Red mud are the two significant parameters with 53.59 and 44.92% contribution each, respectively. Under the optimized parameters, pH value of Red mud slurry reaches to about 8.0 which is within disposable limits. When seawater or other Ca- and Mg-rich brines are added to caustic Red mud, the pH of the mixture is Reduced causing hydroxide, carbonate or hydroxy carbonate minerals to be precipitated. This mechanism of neutralization process has been explained with emphasis on chemical analysis, mineralogy and morphology of the neutralized Red mud. The process improved the physical characteristics of Red mud with entrained liquor becoming non-hazardous water with Reduced alkalinity. The results would be extremely useful in the process of safe disposal of Red mud.

Background: Bisphenol A, a toxic environmental pollutant released from industries, can be dangerous even at low concentrations. The aim of this study was to investigate the adsorption of bisphenol by Red mud modified with nitric acid.Methods: Red mud was modified with nitric acid and washed with distilled water. It was then dried at 103oC for six hours and seived (mesh size: 100). The optimum equilibrium time was determined in various bisphenol concentrations and doses of adsorbent. The optimum amount of bisphenol, dose of adsorbent, and pH were calculated by keeping the optimum equilibrium time constant. Isotherms and kinetic relations were determined by using equiliberium data.Results: Increasing contact time and dose of adsorbent enhanced the adsorption of bisphenol; there fore, increasing contact time from 10 to 210 minutes increased the adsorption from 43% to 84%.Increasing adsorbent dosage from 2 to 20 g/l increased adsorption from 40% to 82 %. Adsorption was also promoted by decreasing the initial concentration of bisphenol. The best pH for bisphenol removal was 3. The adsorption data was best fitted to the Freundlich isotherm and pseudo-second order kinetic model.Conclusion: Red mud is a waste product from the industrial processing of aluminum. According to our findings, it can be used as an effective, low-cost, and available adsorbent to remove bisphenol from industrial wastewater.

Background: and purpose: Dye is one of the problems of industrial effluent such as textile industries. The dyes can be removed by various methods. Therefore, the aim of this study was the evaluation of adsorption rate of reactive Red 198 from aqueous solution by activated Red mud.Materials and methods: This research was a lab study. Activated Red mud was used as an adsorbent to remove reactive Red 198 dye. The effect of various parameters on performance of adsorbent was investigated and the isotherm of adsorption was determined. The dye concentration was measuRed in wavelength of 518 nm by spectrophotometer.Results: The results indicated that the adsorption efficiency Reduced by increasing of initial dye concentration. Increasing of contact time and adsorbent dose can lead to increasing of the removal efficiency. The maximum removal efficiency was occurRed pH between 2 to 3. The data was best fitted on Frandlich and Temkin isotherms.Conclusion: The Red mud had a satisfactory quality in dye adsorption. It can be used as effective and inexpensive adsorbents for treatment of textile effluent.

Red mud is an important solid tailing with strong alkalinity that is obtained during the extraction of alumina in the Bayer process. The global reserve of Red mud is more than 4 billion tons, and its disposal as tailing has always been a serious environmental problem. This tailing is consideRed as a potential source, due to its high content of valuable metal compounds including iron. In this research work, the extraction of iron in Red mud is investigated by the method of Reduction roasting. The main influencing factors are also investigated. These methods include Reduction in muffle and tube furnace, and temperature, Reduction agent, and additive type are as important factors. Reduction roasting of the samples in a tube furnace, with Argon gas and vacuum, a mixture of Red mud, graphite, and sodium carbonate at 700–1000 °C results in the formation of Fe3O4. Magnetic measurements indicate that saturation magnetization increases from 0.239 to 38.205 emu/g due to the formation of Fe3O4. Applying the magnetic field intensity of about 1000 Gauss results in the iron recovery of 89.9%.

Minerals, depending on their composition and origin, contain some radioactive nuclides. Presence of such radionuclides such as 238U, 232Th and 40K in materials are dangerous when they are highly concentrated and influence on human exposure. Bauxites as a raw material for aluminum may contain relatively high amount of those radionuclides, which are more concentrated in remained Red-mud after Al production process. Due to high existing of iron oxides in the Red-mud, it is preferRed to be used in recycled products such as cement and brick.Because of high amount of radionuclides in Red-mud, its radioactivity should be determined and decrease their environmental impact before using in industry. Therefore, radiation of Red muds from Jajarm bauxite mine, which is the biggest bauxite deposit in Iran (with 1000000 tones Redmud annual production), have been determined in this study. Finally, after determination of average radiation of Jajarm Red-mud, the mixing ratio of Red-mud to low-radiation materials (such as clay minerals) was calculated for using in construction materials, under standard level of radiation.

In this work, the influence of Red mud in the pyrolysis of general purpose polystyrene (GPPS) has been studied. The catalytic pyrolysis experiments were carried out using an unstirRed semi-batch stainless steel 6.28 liter reactor under nitrogen atmosphere (air free) with Red mud as a catalyst. The reaction effluents (oil and gases) were condensed in water-cooled condenser. The condensate was weighted to determine the total yield. Gas Chromatography-Mass Spectroscopy (GC-MS) analysis was used to characterize the condensed liquid organic compounds. According to the GC-MS results, styrene, benzene and its derivatives, toluene, naphthalene and a small amount of the other hydrocarbon compounds were identified in condensate liquid. Density, specific gravity, API gravity, kinematics and dynamic viscosity, flash point, fire point, cloud point and pour point of condensate were also measuRed. Under optimum reaction condition, the yield of pyrolysis reaction was above 90%. The air free reaction condition showed good catalytic pyrolysis of polystyrene with less than 1% coke formation and above 90% selectivity towards formation of aromatic compounds. The specifications of condensate, i.e. density, API gravity, viscosity and flash point observed showed that the liquid obtained can safely be classed as a kerosene. The specific gravity value was close to the specific gravity value of diesel.

In this study, absorption of sulfates on activated aluminum industry waste (Red mud) has been investigated in a batch system by OFAT method. The properties of the absorbents were analyzed using scanning electron microscope (SEM), BET surface area, X-ray diffraction (XRD), XRF. The process of sulfate absorption was done in a volume of 200 mL and a mixer speed of 150 rpm. The optimum adsorption conditions were derived for in an equilibrium time of 90 minutes, the initial concentration of 100 ppm, pH=4, the temperature of 65 ◦, C and 1. 5 g/L dose of the absorbent. The efficiency of sulfate removal was 73. 1 percent at the optimum conditions. Thermodynamic analysis of absorption showed that the absorption process at all analyzed temperatures had occurRed spontaneously. Sulfate adsorption kinetics on composite surfaces followed a pseudo second order equation and absorption isotherm had a high conformity with Langmuir, Dobinin-Radoshkovich and Temkin isotherms respectively and the maximum absorption capacity of it according to Langmuir isotherm is 13. 07 mg of sulfate per gram of the absorbent.

Due to growing interest in using TiO2 and Reducing its primary resources, many researches have been carried out to recover TiO2 from industrial slimes. Red mud is obtained during alumina production from Bauxite by bayer process. It contains considerable amount of TiO2. The nature of compounds in Red mud is complex, therefore hydrometallurgical processes have been found more efficient for the recovery of TiO2. In order to recover TiO2 from Red mud, several work have been done in laboratory and pilot scale using hydrometallurgical and combination of hydro-pyrometallurgical processes. In this research, characterization of Red mud and its applications were studied followed by considering recovery methods for the production of TiO2 from Red mud. Also, in this research identification of Red mud that generated during alumina production in Jajarm were studied.

In the Bayer process, the reaction of silica in bauxite with caustic soda causes the loss of a great amount of NaOH. In this research, the bound-soda losses in Iran Alumina Complex solid residue (Red mud) are pRedicted using intelligent techniques. This method, based on the application of regression and artificial neural networks (AAN), has been used to pRedict Red mud bound-soda losses in Iran Alumina Company. Multilayer perceptron (MLP), radial basis function (RBF) networks and multiple linear regressions (MLR) were applied. The results of three methodologies were compaRed for their pRedictive capabilities in terms of the correlation coefficient (R), mean square error (MSE) and the absolute average deviation (AAD) based on the experimental data set. The optimum MLP network was obtained with structure of two hidden layers including 13 and 15 neurons in each layer respectively. The results showed that the RBF model with 0.117, 5.909 and 0.82 in MSE, AAD and R, respectively, is extremely accurate in pRediction as compaRed with MLP and MLR.