Recovering iron values from iron ore slimes using cationic and anionic collectors

Indian iron ore industry is one of the world’s largest and growing at a rapid pace. Approximately 15% of the plant input is discarded as slime into slime ponds. Slime dams are now considered as threat, due to lack of high grade ores and acute shortage of land. More over this slime also poses threat to the environment. In addition to the economic benefit from the utilization of the waste as a resource; it also minimizes the land requirement, surface degradation, groundwater pollution, and destruction of forests. Iron ore beneficiation plants in India gives in three products, coarse ore lumps, which are directly charged to blast furnace, the classifier fines with or without beneficiation are fed to sinter plants and the slime which contain high alumina and low Fe currently discarded as waste. Slimes are to be further beneficiated to produce concentrates low in alumina and silica. These slime which after pelletization can be used as burden for the blast furnace. In order to utilize iron ore slime an efficient gangue removal flotation process is indispensable. This research work presents the flotation route for the removal of gangue in the slime to a level which is acceptable for the blast furnace route production of iron. Research has been carried out effectively and efficiently to utilize iron ore slime from the slime ponds of Joda and Noamundi region, India. This research work presents the results on the application of flotation to obtain the hematite and goethite concentrate with low gangue content from iron ore slimes. Fine particle size, complex mineralogy and presence of locked particles make it impossible for direct production of hematite concentrate by froth flotation unless mineral surface specific collectors are used. With flotation of silicates by using cationic collector and starch as a depressant for iron ore, starch adsorption occurred on quartz particles covered by iron oxides and on minerals which contain, Fe (II), Fe (III), and Al ions in their structure. An entire flotation of mineral complex is possible if the collectors used are mineral surface specific. Flotation performance was optimized by carrying out design of experiments

Parametric optimization and rate laws determination for the conversion of 4-tert-butylbenzoic acid to methyl 4-tert-butylbenzoate

289-299The esterification of 4-tert-butylbenzoic acid has been studied to produce methyl 4-tert-butylbenzoate, having its widespread applications in the pharmaceuticals, perfumes, flavor, cosmetics, and fragrance industries. The limiting nature of the reaction is catalyzed with methane sulphonic acid, a green catalyst. The study focused on optimization of the experimental parameters to achieve higher conversion of acid with the aid of statistical analysis based on the Taguchi technique. An L9 array, S/N ratios, and ANOVA have been used with catalyst concentration, molar ratio and time as the process parameters with acid conversion as the response variable. Parametric optimization based on Taguchi method suggest a combination of optimal parameters as 10% catalyst concentration, 5:1 methanol to acid molar ratio and 2 h at a refluxing temperature of 67°C. A kinetic investigation for the esterification is also conducted to define the rate equations that govern the overall progress of reaction and the results established that the reaction follows irreversible pseudo second order rate in the initial phase followed by the reversible second order rate. The proposed model is found to be in good agreement with the experimental results

Measurement and Correlation Studies of the Saturated Vapor Pressure, Density, Refractive Indices, and Viscosity of Methyl 4-<i>tert</i>-Butylbenzoate

The saturated vapor pressure of methyl 4-<i>tert</i>-butylbenzoate was measured from (1.21 to 34.66) kPa in the temperature range from (398.3 to 492.4) K using a Swietoslawski-type ebulliometer. The experimental data were fitted with the Antoine and Clarke–Glew equations, which yielded Antoine parameters (<i>A</i> = 18.031, <i>B</i> = 7261.445, <i>C</i> = 8.857 K) and standard vaporization enthalpy (Δ_l^g<i>H</i>_m^θ (298.15 K) = 57.49 kJ mol^–1), respectively. The critical properties were estimated on the basis of group contribution method. The acentric factor was calculated using these critical parameters and the saturated vapor pressures with the Antione equation. Furthermore, density, refractive indices, and viscosity of methyl 4-<i>tert</i>-butylbenzoate were also measured in the temperature range of 293.15 to 353.15 K. Temperature-dependence correlation equations for the density (second-order polynomial equation) and viscosity (Vogel–Tamman–Fulcher) were proposed. Modified Rackett equation was used with group contribution methods to predict the density of methyl 4-<i>tert</i>-butylbenzoate. Group contributions and group interactions method of Nannoolal et al. were used to predict the viscosity in the temperature range of 293.15 to 353.15 K

Measurement and Modeling of Solid-Liquid Equilibria of l -Glutamic Acid in Pure Solvents and Aqueous Binary Mixtures

The experimental solubility data of l-glutamic acid in pure water, formic acid, methanol, 1-propanol, 2-propanol, acetonitrile, and binary mixtures (formic acid + water, methanol + water, 2-propanol + water, acetonitrile + water) with different compositions were carried out at temperatures ranging from (283.15 to 328.15) K by the static analytic method. The solubility measurements showed that formic acid and its aqueous mixtures recorded a higher solubility than methanol + water, 2-propanol + water, and acetonitrile + water for the same composition at each temperature. Moreover, except formic acid the addition of methanol, 2-propanol, and acetonitrile to its aqueous mixtures resulted in the decrease in solubility of l-glutamic acid. The experimental data was fitted using different thermodynamic models such as the Buchowski-Ksiazczak equation, the Van&#039;t Hoff equation, the modified Apelblat equation, and the NRTL model, and the optimum values of the regressed parameters were obtained. The modified Apelblat equation, Buchowski-Ksiazczak equation, and NRTL activity coefficient model were fitted to the pure solvents solubility data, while the modified Apelblat, modified Apelblat-Jouyban-Acree, and NRTL models were used for the binary solvent systems. The results demonstrated formic acid as a cosolvent in the dissolution of l-glutamic acid in formic acid + water binary mixtures, while others exhibited an antisolvent effect on the solubilization of l-glutamic acid in their respective aqueous mixtures