Dissolution of ulexite-containing clay minerals in sulfur dioxide-saturated water

Turkey has approximately 60% of the boron ores of the world. Boron in general is found as calcium or sodium borates or both in nature. Ulexite, which is one of the most widely available boron minerals, has the chemical formula of Na2O center dot 2CaO center dot 5B(2)O(3)center dot 16H(2)O and triclinic crystal structure. In addition, it is generally found to contain some clay minerals, which cause trouble in filtration processes. The dissolution characteristics of ulexite in water saturated with SO2 was investigated, and a discussion about whether this new process can provide an alternative in terms of the products obtained was made in the current study. The parameters selected for the study are particle size, reaction temperature, solid-to-liquid ratio, and stirring speed. The ulexite dissolution rate was found to increase with decreasing particle size and solid-to-liquid ratio and with increasing reaction temperature, while it was not affected by stirring speed. The activation energy of the dissolution process was 49.87 kJ(.)mol(-1). A model equation was constructed for the process. Evaluation of the experimental data and the mathematical model revealed the dissolution process to be controlled by chemical reaction. Furthermore, the solid waste of the process was found to be easily and quickly filterable, and the boron lost was less when compared to sulfuric acid and other similar processes. The byproduct of the proposed process, CaSO3, can be used in many different industries, as an antichlor in the textile industry, as a disinfectant in the sugar industry, in brewing, in biological cleansing, in preservation, and as a discoloration retarder in the food industry. In addition, this process can be said to be an environmentally friendly one.