Basic Research On Coal Spontaneous Combustion Inhibition Technology

Because basic research of the theory about inhibition technology for coal spontaneous combustion is not adequate,the quantum chemistry theory is used to study the basic theory about inhibition technology for preventing coal spontaneous combustion In microcosmic view for the first time.With B3LYP/6-311G density functional theory is used to study the process of forming coordination chemical bond and ligand between active groups of coal including N,P,S and inhibitor.The theory of inhibition mechanism for preventing coal spontaneous combustion is founded.The core content is that coordination chemical bond and ligand between active groups including N,P,S,O,etc in organic macromolecule and low molecular weight compounds of coal and metal ions in inhibitor are formed,which decrease the reaction activity between oxygen and active groups.It is a breakthrough of traditional theory and academic view that water film,separating oxygen,is formed on coal surface after strong salts attaching there absorb water.It also fills the gaps in field of studying inhibition mechanism for preventing coal spontaneous combustion. The main research contents and achievements are as follows:Through infrared spectrum experimental study and quantum chemistry calculation, based on the molecular structure model of coal,on B3LYP/6-311G density functional theory is used to obtain structure model and frontier orbital figure of coal molecule after simplification and determine that active groups like-NH₂,-PH₂,and-SH in coal molecule have high chemical activity and therefore are easy to loss electron and form coordination bond with metal ions,and at the same time coal spontaneous combustion is easy to happen.The process of forming coordination chemical bond and coordination compound between active groups of coal molecule and ions like Mg²⁺ and Na⁺ is studied.After calculating and analyzing natural bond orbital,net charge population and natural electron configuration of forming complex,strong interaction energy between lone pair electrons of atoms like N,P,S in coal molecule and ions like Mg²⁺ and Na⁺ and unoccupied orbital is discovered.Meanwhile,atomic orbital of ions like Mg²⁺ and Na⁺ gets part of feedback electrons from ligand and deviates its apparent charge,which illustrate that coordination bond is formed between Mg²⁺,Na⁺ and N,P,S in ligand.After analyzing stabilization energy and frontier orbital energy level,it is obtained that four-coordination and three-coordination compounds forming from Mg²⁺ and active groups N,P,S are the most stable,and four-coordination compounds forming from Na⁺ and active group P is not.Stabilization energy of complex forming from Mg²⁺ and active groups N,P,S is far more than that from Na⁺ and active group N,P,S.The maximum energy from the former one is 6.81 times than that from later one,and the minimum energy from the former one is 2.14 times than that from later one.Stability of complex forming from Mg²⁺ and active groups N,P,S is higher than that from Na⁺ and active group N,P,S.Therefore,it is showed that the essence of inhibition mechanism for preventing coal spontaneous combustion is coordination chemical bond and ligand between active groups of coal and metal ions are formed,which decrease the reaction activity between oxygen and active groups.Theoretical problem of Mg²⁺,Na⁺ preventing coal spontaneous combustion is solved from microcosmic view.