Activation Of Gold Tailings Powder And Its Effect On Concrete Performanc

Under the background of the dual-carbon strategy,to further improve the utilization level of solid waste,promote the comprehensive utilization of resources and industrial energy conservation and carbon reduction.This thesis takes Zhaoyuan gold tailings as the research object,and uses the mechanical-chemical-thermal coupling activation method to stimulate the potential pozzolanic activity of gold tailings.The use of activated gold tailings powder as supplementary cementitious material for concrete reduces the amount of cement,thereby reducing carbon dioxide emissions and recycling solid waste,helping to achieve carbon peaking and carbon neutrality.First,this thesis uses the method of mechanical grinding to activate the gold tailings.The effects of mechanical grinding on gold tailings’ particle characteristics and mineral composition were analyzed by an automatic specific surface area analyzer,a laser particle size analyzer,an X-ray diffractometer(XRD),and a scanning electron microscope(SEM).The effect of mechanical grinding on the potential pozzolanic activity of gold tailings was analyzed by the compressive strength ratio test of cement mortar test block and the pozzolanic test.The main mineral phases of gold tailings are quartz,muscovite,albite and microplagioclase,which have high crystallinity and are aluminosilicate materials with potential pozzolanic activity.Mechanical grinding can reduce the particle size of gold tailings,increase the specific surface area of gold tailings,and reduce the crystallinity of the main mineral phases of gold tailings,but cannot stimulate the potential pozzolanic activity of gold tailings.The mechanically ground gold tailings powder mainly played the filling effect of micro-aggregates and the nucleation effect of C-S-H gel in the cement block.Then,a mechano-chemical-thermal coupled activation method was used to stimulate the potential pozzolanic properties of the gold tailings.The optimal activation process of gold tailings was determined by orthogonal test and response surface optimization test: 8 % calcium oxide and gold tailings were mixed and ground for 60 min,then calcined at 600°C for 60 min.The strength activity index and pozzolanic reactivity of gold tailings powder under various activation methods were evaluated by the compressive strength test of cement mortar test block and the pozzolanic test.The activation mechanism of gold tailings and the hydration performance of activated gold tailings powder were studied by XRD,SEM,Fourier transform infrared spectroscopy(FTIR),and energy-dispersive X-ray spectroscopy(EDS),thermogravimetric analysis(TG-DTG)and other experimental methods.The research results show that the 28 d compressive strength ratio of the mortar test block mixed with mechanical-chemical-thermal coupling activated gold tailings are 95.60 %,and the consumption ratio of [Ca O] in the slurry of coupled activated gold tailings is 60.76 % at 15 d,so the coupled activated gold tailings powder has a higher pozzolanic activity.High-temperature calcination can remove the structural water in muscovite to make it decompose.In the presence of calcium oxide,high-temperature calcination is conducive to the depolymerization of siloxane radicals and further improves the pozzolanic activity of tailings.With the increase in the amount of gold tailings powder,the content of calcium hydroxide in the hardened slurry decreased,and the content of C-S-H gel and hydrated sulfoaluminate increased,confirming that the coupling activated gold tailing powder has high pozzolanic activity.Finally,activated gold tailings powder was used as supplementary cementitious materials for concrete.The effects of activated gold tailing powder and the mixing of activated gold tailing powder and slag powder(SL)in different proportions on the working performance,mechanical properties and durability of concrete with different strength grades of C40 and C60 were studied.The influence of activated gold tailings powder and its compounding with slag powder on the concrete of two strength grades was analyzed,and the optimum amount of activated gold tailings powder and the optimum compounding ratio of slag powder and activated gold tailings were obtained.To ensure the concrete works well and reaches the standard compressive strength value within 28 days,the content of MGT(Mechanically activated gold tailings)should be controlled within 20 %,the content of CGT(Coupling activated gold tailings)should be controlled within 40 %,and the content of GSL(CGT and SL were mixed in a ratio of 6:4)should be controlled within 60 %.The long-term compressive strength stability of the concrete mixed with MGT,CGT and GSL is good.Compared with the90 d compressive strength of the concrete,the 180 d compressive strength of the two strength grades does not decrease significantly.When adding CGT within 40 % and GSL within 60 %to C40 and C60 concrete respectively,the frost resistance and sulfate corrosion resistance of concrete can be improved,and the concrete has good durability.