Effects of ultrasound on the reaction step of boric acid production process from colemanite

Abstract

Colemanite is one of the most important boron minerals used for production of boric acid. Boric acid (H(3)BO(3)) is produced by the reaction of colemanite (2CaO.3B(2)O(3).5H(2)O) with sulfuric acid in a heterogeneous solid-liquid reaction leading to crystallization of gypsum as a byproduct. The influence of ultrasound on the dissolution of colemanite in H(2)SO(4) solution and on the precipitation of the gypsum during the reaction was investigated. Experiments have been carried out in a batch stirred vessel at 85 degrees C in the absence and presence of ultrasound. The stirring rates were chosen as 600 rpm (for 500-600 microm) and 800 rpm (for 1000-1180 microm) to provide a homogeneous suspension during the reaction. The boric acid and calcium ion concentrations in the solution were determined as a function of time. The results showed that ultrasound enhances the dissolution of colemanite and precipitation rate of the gypsum in the solution after 1h. It has been shown that the use of ultrasound decreases the size of gypsum crystals.

Dissolution kinetics of ulexite in acetic acid solutions

“…Boric acid is most commonly used as a primary material in the preparation of many boron chemicals such as synthetic organic borate salts, borate esters, boron carbide, fluoroborates, and boron tri-halides. The preferred commercial method of preparing boric acid is by way of digestion of alkali and alkaline earth metal borates with concentrated mineral acids followed by crystallization of boric acid (Shiloff, 1968;Taylan et al, 2007). In Turkey, boric acid is obtained from the reaction of colemanite and sulfuric acid in accordance with heterogeneous solid-liquid reaction (Mergen et al, 2003).…”

“…This process has some disadvantages such as sulphate contamination in final product, and environmental pollution. When gypsum is discharged into the environment, it causes soil and especially groundwater pollution because of its boron content (Özmetin et al, 1996;Temur et al, 2000;Kurtbaş et al, 2006;Taylan et al, 2007;Ekinci et al, 2007).…”

Investigation dissolution behaviours and kinetics parameters of ulexite in boric acid solution

“…Fluid + Solid Reactants → Fluid and solid product (9) Solid Reactants → Fluid products (10) Solid Reactants → Fluid and solid products (11) In reactions with the excessive liquid phase, the concentration is considered to remain constant during the reaction. 33,35,38,41,47 The equations that is applied to systems where such a liquid component is constant and our evaluations of the results for different models are given in Table 3.…”

“…Alkaline and alkali borates, metals mixed, acidic minerals, and crystallized boric acid are the other chemicals that are produced from boron minerals. Generally, commercial methods have been preferred to fabricate boric acid 11,12 So far, various acids have been used by reacted with boron minerals to obtain boric acid.…”

Cinética de la disolución de ulexita calcinada en soluciones de sulfato de amonio

“…Thus, in order to improve alternative boric acid production process, many studies have been carried out by researchers. The researchers have concentrated to clarify the kinetics and mechanism of boron minerals dissolution (particularly colemanite and ulexite) in various inorganic and organic leaching solutions (Taylan et al, 2007;Bulutçu et al, 2008;Ekmekyapar et al, 2010;Künkül et al, 2012).…”