Abstract:
There are many rare metal elements associated with stone coal,which had great potential for exploitation and utilization.The occurrence state of rare metal elements limits the possibility and efficiency of their extraction from stone coal,and also determines the migration and transformation ability of harmful elements to the surrounding environment.Based on the characteristics of stone coal,an experimental scheme for the analysis of the occurrence state of rare metal elements in stone coal was designed.According to the principle of material balance and relevant parameters,the experimental results were systematically evaluated and verified.It was considered that the scheme design is reasonable,logical,maneuverable and the results are reliable,which is suitable for the study of rare metal elements in stone coal.The distributions of rare metal elements in different occurrence states were analyzed.It was concluded that there were various occurrence states of rare metal elements in stone coal,mainly in inorganic state,among which the majority was in the mixed mineral state.Zr,Nb,Hf,Ta were closely bound to miscellaneous mineral state (Quartz,illite and insoluble silicate minerals).Li,V,Cr,Ga,Y,Ba,Bi and Th were mainly in the form of miscellaneous mineral state.Cu,Rb,Mo,Cd,Sb,W were closely related to organic matter.Co,Ni,Zn,Y,Cd,Bi,Th were related to carbonate minerals.Y,Mo,Tl,Th had a small amount of oxidation state.Other elements had low content of oxidation state.Co,Ni,Cu,Zn,Mo and Cd had a certain amount of water soluble forms.Most of the elements did not exist or had a trace adsorption state.The results could help guide the joint development of rare metal elements and slow down the migration of harmful elements to the surrounding environment.According to the occurrence characteristics of rare metal elements in stone coal,it is suggested to select a mild and controllable scheme of destroying organic matter in the extraction process design of stone coal rare metal elements,after the destruction of organic matter,inorganic mineral elements should be extracted,focus on the joint extraction of rare metal elements in “miscellaneous state”,and pay attention to the recovery of residue and waste liquid,in order to reduce and monitor the migration and transformation of harmful elements to the environment.