An experimental study was conducted to determine the effects of the LEACHING parameters on impurity ion concentrations of the liquid phase in ulexite LEACHING. Powdered ulexite ore was leached in an aqueous medium with sulfur dioxide. The Taguchi experimental design approach and statistical methods were used to evaluate the effects of the LEACHING parameters (solid/liquid ratio, temperature, pH, particle size, time) on impurity ion concentrations (concentrations of magnesium, calcium, iron ions) in the liquid phase. The average B2O3 LEACHING ratio of ulexite ore was found as 98. 56 % (± 0. 95). Statistically effective LEACHING parameters on impurity concentrations (and delta values for concentrations) were found as pH (770 ppm) for magnesium, solid/liquid ratio (372 ppm) for calcium ion concentrations. The examined parameters were not found effective for iron ion concentrations.

The LEACHING kinetics of smithsonite ore in acetic acid solutions, an environmental friend, and natural reagent was investigated. The influence of parameters such as reaction temperature, particle size, solid-liquid ratio and acid concentration was studied in order to reveal the LEACHING kinetics of smithsonite ore. In this study, experimental and statistical methods were carried out in order to analyze the kinetics data to investigate a kinetics model which describes the dissolution. The results indicate that the unreacted shrinking core model for fluid-solid heterogeneous reactions was favorable for the LEACHING process. The apparent activation energy of the LEACHING process was found as 74 kJ/ mol. It was determined that the LEACHING rate of smithsonite was controlled by the chemical reaction below: (1-x)1/3=3.7×105e-74/RTt.

The reclamation of saline‐ sodic soils is an important issue in agriculture and agronomy programs. In arid and semiarid areas, rainfall is not sufficient for LEACHING of salts from root zone and excess of soluble salts in the soil root zone can reduce water uptake of the plant. This is due to the decrease in the osmotic potential of soil solution and also degradation of soil structure because of sodium which could be toxic to the plant. In this field study reclamation of saline‐sodic soils at four stations in Minab, south of Iran was investigated. The experimental design of the study was double‐ring. The LEACHING was investigated up to 100 cm depth of soil. As the LEACHING process continued, soluble salts were washed away from soils profile of the agronomy programs and the salinity of the soil surface layer were reduced to a level suitable for cultivation of salt tolerant and semitolerant plants.

The LEACHING kinetics of stibnite in basic solution has been investigated. Spherical pellets of antimony sulphide were dissolved in 1 molar sodium hydroxide solutions at different temperatures. It was found that the shrinking core with ash layer model could satisfactorily explain the dissolution process. Using this model, it was found that initially the rate controlling step was a chemical reaction with activation energy of 10.2 kJ/mol. As the ash layer built up, diffusion through the ash layer became the rate controlling step. The activation energy for this step was found to be 33.4 kJ/mol. It was also observed that smaller particle size, larger solid to liquid ratio, and higher NaOH solution concentrations resulted in higher concentrations of stibnite in the leach solution.

In this study a mathematical method called PSPD (profile side-pore diffusion) based on the work of Bouffard and Dixon [10] is proposed for simulation of solute transport through the pores of a heap, considering the reaction terms. The obtained governing equations are converted into dimensionless forms and are solved by writing a computer program based on an implicit finite difference method. The solution of the model results in the outlet acid concentration profile. In order to check the accuracy of the proposed model and also for determination of effective diffusivity of sulfuric acid in copper oxide ore particles, two experimental setups are constructed, one for measurement of the effective diffusivity and the other for measuring the rate of LEACHING. The effective diffusivity is obtained by two different methods which reconfirm each other. The copper oxide ore of Sarcheshmeh copper complex, situated in Kerman province in Iran, was used for experimentation. The effects of different factors such as particle size, acid solution flow rate and initial acid concentration are examined on the rate of LEACHING in two columns of different heights.Comparison of the calculated data with experimental data under the same operating conditions shows a good agreement between them and hence validity of the proposed model was confirmed. The results show that the extraction time of copper is influenced mostly by increasing the acid solution flow rate and decreasing the column height due to decreasing the advection time.

A new process for recovering scheelite ores comprises producing a concentrate from the ore, then LEACHING the concentrate with H_2SO_4 in the presence of H_3PO_4 and Na Cl at atmospheric pressure are discussed. Finely purification of the product will be described. The amounts of dissolution of tungsten in acid depend on the parameters such as time, temperature, type and concentration of acid and stilt as well as solid-liquid reaction. These factors were optimized for the result and described in details.

Environmental issues of hazardous metal wastes as well as growing demand for metals has increased focus on the forthcoming provision of metals. Therefore, the recovery and recycling processes of precious metals from secondary resources have become more prominent in the last years. Silver is one of the precious metals which can be recovered from wastes such as electronic wastes, coin and medal production losses, photographic films, and dental filling materials known as amalgam, which has the highest silver content. The present paper investigates the acid LEACHING of metals from a waste sample of dental silver alloy generated during the melt spray process. The alloy constitutes of 42. 13% Ag, 31. 03% Sn, and 26. 84 Cu. The phase composition of amalgam generally consists of Ag2Hg3, Ag3Sn, SnxHg, Cu6Sn5, and Cu3Sn. The effects of the system temperature (25-80° C), nitric acid concentration as the leachate (13. 75-65%), pulp density (33-200 g/l), and reaction time (0-240 min) on the dissolution recovery of silver, copper, and tin have been investigated. In the best case, we recovered 100% of silver and 98% of copper as soluble nitrates while tin was isolated as solid stannic oxide.