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: 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%.

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 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.