Molecular Dynamics Simulation Of The Occurrence Of Boric Acid And Magnesium Sulfate In Hydrothermal Conditions

Based on the current status for mineral resources of magnesium and boron in China and the practical problems of difficult separation of boron and magnesium in the acid production process,not only the waste of resources,but also environmental pollution problems,so that the production of boron industry in China is in an unfavorable situation of overall losses.Therefore,the effective separation of boron and magnesium in the solution system is the key to solving production problems in the boron industry,and relevant basic research is particularly important.Molecular dynamics simulation method is an important visualization method for studying the behavior and association characteristics of particles in solution system.It is of great significance to understand the state of particles in solution under high temperature and high pressure system.This article reported molecular dynamics simulation to study the structures and occurrence of the particle in the system of MgSO4-H2O,H3BO3-H2O and MgSO4-H3BO3-H2O.Under the research system,the following main conclusions are obtained.(1)In the system of MgSO4-H2O,the effect of temperature and concentration on the total coordination number of Mg2+ is not obvious in solution,and tends to be a six-coordination structure.The direct contact ion pair is the main existing mode of particles in solution system.And with the increase of temperature and concentration,the binding energy of magnesium 2+sulfate and water in the system can be reduced,the hydration coordination number of Mg2+decreases,and the association coordination number of Mg2+ increases gradually,which causes the polymerization degree of cluster particles to increase.The shape of the polymer gradually changes from spatial network to a long-chain large cluster.(2)There are mainly free boric acid molecules and associative boric acid molecule pairs in H3BO3-H2O system.Hydrogen bond is the main mode of association between boric acid molecule and boric acid and water molecule.With the increase of temperature and the decrease of boric acid concentration,the binding energy between boric acid and water molecule decreases gradually.When the mass fraction of boric acid was greater than or equal to 7%,a small amount of boric acid molecule association phenomenon begins to appear in the system.(3)In the system of MgSO4-H3BO3-H2O,the binding energy of magnesium sulfate to water decreases with the increase of B/Mg ratio.The total coordination number of Mg2+increases to 7 coordination,compared with the two systems.With the increase of B/Mg ratio,the coordination number of Mg2+ with H2O decreases,and the coordination number of Mg2+with SO42-increases gradually.Boric acid can effectively promote the formation of magnesium sulfate clusters.The larger the B/Mg ratio,the higher the aggregation degree of the large clusters in the system,and the shape of clusters gradually changes from spatial network to long-chain.(4)In the system of MgSO4-H3BO3-H2O,increasing temperature is beneficial to increase the association of Mg2+,and the synergistic effect of temperature and boric acid is positively correlated with the formation of large clusters of magnesium sulfate.