Study On Multi Field Coupling Analysis Of Flow Solid Chemical Of Tailing Dam Based On Acedizing Test

Tailing pond is not only a necessary condition to ensure the normal production of mineral processing plant,but also a potential threat to the occurrence of disaster accidents.Our country is a large number of tailing pond,and also a large number of ill and dangerous tailing pond.The safety and stability of tailing pond has become a key issue of all walks of life.Tailing acidification is a common objective phenomenon in tailing of sulfide mines.In sulfide mines,tailing sand particles are relatively fine.With the accumulation of accumulation time,under the catalysis of oxidizing bacteria,water,oxygen,oxidant(such as Fe³⁺,etc.),the sulfide minerals?FeS₂?contained in tailing will oxidize to generate sulfate and sulfuric acid.The acid waste liquid from tailings oxidation will further reacts with metal oxides in tailings to form insoluble precipitates.The oxidation and decomposition reaction of tailings will produce corrosion on the dam body of tailings dam,change the relevant physical and mechanical properties of tailings dam,and affect the long-term stability of tailings dam.Based on the key scientific research project of Hunan Provincial Department of Education?subject No:18A252?,this paper studies tailings acidification by means of chemical,physical and mechanical tests in combination with the indoor soaking experiment of tailings sand;on the basis of the experiment,the chemical field?C?equation,stress field?M?equation and seepage field?H?equation considering the influence of tailings acidification are studied and established,and the M,H and C squares are established In order to study the long-term stability of tailing dam,the m-h-c numerical model is established.The main research contents and conclusions are as follows:?1?The tailing sand in the tailing dam will be oxidized under natural conditions.The oxidation mechanism is that the sulfur-containing metal minerals in the tailing sand,mainly FeS₂,will be oxidized under the catalysis of Thiobacillus ferrooxidans,etc.to generate sulfate and sulfuric acid.Sulfuric acid will continue to decompose with the metal oxides in the tailing sand;?2?In order to study the influence of acidification on the chemical and physical mechanical properties of tailing sand,acid production potential test,immersion test,XRF element detection test,ICP iron element analysis test,specific surface area measurement test and other basic physical tests such as consolidation and direct shear were carried out.It is found that with the deepening of the acidification of tailing sand,a series of changes have taken place in tailing sand particles,including precipitation and dissolution.The particle size is smaller,the internal friction angle is smaller,the specific surface area is larger,the content of iron element is reduced,and the porosity is smaller;?3?The coupling mathematical model of chemical field,stress field and seepage field is established,and the coupling model of seepage field,stress field and chemical field is established by COMSOL multiphysics software.The change of Darcy velocity field,stress-strain and displacement of tailings dam under different oxidation degree is studied.With the deepening of oxidation degree,the maximum Darcy velocity first rises and then falls,and the turning point is?50%?;the stress gradually increases,and the increase range of stress from the beginning of reaction to the completion of reaction is about 80%;the displacement gradually increases,and the horizontal displacement at the completion of reaction is 10.83 times of that at the beginning of reaction.It can be seen that acidification will have a greater impact on tailings sand;?4?Tailing acidification affects the long-term stability of tailing dam by affecting the micro structure of tailing,which is embodied in the gradual decrease of mechanical indexes such as shear strength of tailing dam with the accumulation of tailing accumulation time.The longer the tailing accumulation time is,the larger the decline of indexes is,and the accumulated tailing sand is subject to sliding damage;consolidation settlement makes tailing dam more dense,which is conducive to stability.The comprehensive change of accumulated tailing sand will act on the initial dam,which will affect the overall stability of the initial dam and reduce the overall stability of the tailing dam?in this study,the change of stress and horizontal displacement is used to show the performance and degree of the stability reduction of the tailing dam?.When the force acting on the initial dam exceeds the shear strength of the initial dam,the tailing dam will be damaged;?5?In order to reduce the possibility of dam break and improve the long-term stability of tailings dam,it is necessary to restrain the acidification of tailings under natural conditions.According to the above research,it is found that the tailings dam can be covered to block its contact area with oxygen and slow down the reaction;after beneficiation,alkaline additives are added to the tailings sand to change its acid environment;the activity of Thiobacillus ferrooxidans is inhibited to inhibit the oxidation and acidification of tailings;in the design of the initial dam,the chemical load generated by the tailings dam with the accumulation of tailings sand should be fully considered And seepage force to improve the safety of the initial dam.