Experimental Study On The Impact Of Magnetic Field On Calcium Carbonate Crystallization Process

Scaling phenomena is widespread in heat exchangers, and it brings incalculable loss to production, Physical methods are widely used due to the high automation degree, simplicity of operation and environmental-friendliness in recently years. However, the development of this technology is restricted by a certain degree because there’s no final conclusion on the mechanism. This paper mainly studies the effect of magnetic field treatment on the crystallization process of calcium carbonate, which is helpful to explore the mechanism of fouling mitigation of magnetic treatment because calcium carbonate crystallization is the important stage in the process of calcium carbonate scale formation.This paper mainly studied the effect of different magnetic field on calcium carbonate crystallization in solution of different hardness under different temperature through the conductivity method, coordination titration method and weighing method, meanwhile, the calcium carbonate crystal morphology was observed with biological microscope. For further understanding of the mechanism of magnetically anti-scaling, the physical parameters of water treated in magnetic field were studied, including electrical conductivity, surface tension, viscosity, and the solubility of calcium carbonate in the water.The research shows that crystal formation rate in 3mmol/L’s solution was increased by 14.9% and the crystal growth rate was decreased treated with static magnetic field of 0.42T under normal temperature conditions. So more crystallite was formed in smaller size. The effect was obvious when the initial concentration of calcium ions was between 2-3 mmol/L. As the temperature increases, the effect of static magnetic field is more and weaker, while it’s stronger with the increase of magnetic field intensity. After dealing with the magnetic field of the calcium carbonate crystal tended to turn to aragonite from calcite.The crystallization rate of calcium carbonate in solution which has an initial calcium concentration of 3mmol/L in alternating electromagnetic field of 0.5T can be accelerated by 20%, among which the impact on negative ion was predominant. Factors affecting the effect include the water quality parameters, magnetization time and magnetic field intensity. The effect of the magnetic field was enhanced with the increase of magnetization time and the increase of magnetic field strength.The electrical conductivity of water increases, the surface tension and viscosity were reduced after treating by magnetic field, which means the activity of water was increased. So the magnetized water can prevent calcium carbonate microcrystalline assembling into larger particles, and it can also make the old scale fall off due to the increase of solubility of calcium carbonate.