Studies On Enhancement Of Phosphorite Acid Decomposition By Ultrasonic Wave

Solid-liquid reaction is one of the most common methods for rock processing. With phosphate rock decomposing in the course of reaction, some resultants of reaction will diffuse and separate crystals out. The crystals may deposit on the surface of particles of solid reactant, coat the particles, form a layer of solid film and resist further reaction, if the crystallization happens on the surface of particles, which results in a decreasing reaction rate or even stopping reaction.Sonochemistry is a new branch in chemistry and chemical engineering. The effects of ultrasound can be used to intensify the process of mass transfer, heat transfer and chemical reaction and raising the chemical process. According to the characteristics of ultrasonic cavitation in solid-liquid system resulting surface, energy, turbulent and micro-disturbing effects, the mechanism of ultrasound to intensify mass transfer process was analyzed. It is the most important solid-liquid reaction that sulfuric acid decomposes phosphate rock in phosphate fertilizer production. By contrast with conventional reaction of acid decomposing phosphate rock, the effects of ultrasonic power, reaction time, and temperature are discussed.The results show that under a certain condition, ultrasonic wave can prompt the decomposing Teaction of acid-phosphate rock, accelerate reactant rate; enhance crystal deposit of resultants of reaction, grain refining and homogenization, and keep original crystal habit, crystal structure and component. Ultrasonic wave can also bring "thermal effect" and "non-thermal effect". The experimental results show that the decomposition ratio increases with the ultrasonic power, reaction time and temperature. When increase the ultrasonic power, the ultrasonic density and solute athletics rate all increase, intensify the impact which made in ultrasonic cavitation and corrade degree to gesso, heighten the decomposition ratio. In reaction initial stage, CaSO₄ crystal uncreated, pervasion progress mainly depend on the thickness which is impetus, reaction rate very rapid, hoist temperature can help pervasion or carry through reaction progress. Whether have ultrasonic wave, the decomposition ratio not half alter. When form solid film, cavitate bladder blow up in ultrasonic power, bring thousands K high temperature in the thumbnail time and the thumbnail spare, go with strong bow wave and mirshoot flow, it can intensify the process of mass transfer, so reaction rate with ultrasonic wave have higher than without ultrasonic wave.Some process parameters were sought out by orthogonal experiment design at lab,ω(H₂SO₄)98% sulfuric acid, 80W power of microwave, 30 min reactive time and 60℃acid temperature.The relationship of reaction constant and temperature obey Arrhenius equation. Making use of shrinking core model in which the solid granularity is treated as unchanged, the experimental data are regressed to obtain the macroscopic kinetics model. Phosphate rock decomposing in the course of reaction with ultrasonic wave is pervasion progress, dynamics equation as follows:...