Study On The Preparation And Performance Optimization Of Electrolytic Manganese Residue Based Geopolymer

Electrolytic manganese residue(EMR)is an acid leaching waste residue produced by manganese ore slag after sulfuric acid leaching in the process of electrolytic manganese industry production of manganese metal.At present,the treatment method of electrolytic manganese slag is still stacking in the open air.Because the slag contains a large number of soluble heavy metal ions,long-term storage will be polluted by the surrounding environment and even groundwater.It is urgent to study a green environmental protection,large consumption of electrolytic manganese residue,low energy consumption of the resource treatment method.Geopolymer is a kind of inorganic cementing material with three-dimensional network structure,which has the advantages of good compression resistance,acid resistance,alkali resistance,thermal stability and so on.Silica-aluminum raw materials for preparing geopolymers come from a wide range of sources.As electrolytic manganese residue contains a large number of silicon and aluminum components,it is considered as a potential source of silica-aluminum raw materials for preparing geopolymers.In this paper,the factors affecting the compressive properties of the base polymer of electrolytic manganese residue and the curing effect of heavy metal ions in electrolytic manganese residue were studied.Effects of alkaline heat treatment and ball milling on the compressive properties of base polymer prepared by electrolytic manganese residue;Curing effect of electrolytic manganese residue based geopolymer on Pb and Cd heavy metal elements.The main research conclusions are as follows:(1)The influencing factors,leaching toxicity and microscopic characterization of the preparation process of electrolytic manganese residue base polymer were studied.The results show that the reasonable content of electrolytic manganese slag,the content of sodium hydroxide in alkali activator,the water-cement ratio and the curing condition are beneficial to improve the compressive performance of electrolytic manganese slag base polymer.The best preparation condition is electrolytic manganese residue: solid material =0.6,water-cement ratio is 0.25,the content of sodium hydroxide in the alkali activator is 6%,the curing environment is selected oven 80 ?,the curing time is set to 12 h,the compressive strength of the prepared geopolymer sample material can reach 15.6 Mpa.XRD analysis showed that the reaction of silicon,aluminum and calcium in the prepared geopolymer material resulted in the formation of corresponding aluminosilicate compounds.Ft-ir results showed that amorphoussilicate derivatives were formed during the reaction,indicating that geological polymerization occurred.SEM analysis shows that the internal structure of geopolymer is compact and the cementation between materials is good.The leaching toxicity of the sample material was also studied.The results showed that manganese,the main extruded material in the raw material,increased from the initial 2250 mg/L to 0.56 mg/L,and the other heavy metal substances decreased significantly,indicating that the fixation effect of harmful substances was better.(2)The effects of alkali heat treatment and ball milling on the compressive properties of electrolytic manganese slag base polymer were studied.The results showed that by increasing the heat treatment temperature,adding alkaline substances and prolonging the heat treatment time,choosing the appropriate ball grinding method,adding ball grinding auxiliary agent and the amount of auxiliary agent,the compressive strength of the sample material could be improved.The best technological parameters for alkali heat treatment are: the mass ratio of electrolytic manganese slag: sodium hydroxide =1:0.3 is used for mixing.The solid powder obtained after heat treatment at 600 ? for 1.5 h has the best compressive strength,up to 38 MPa.Wet ball grinding method was used.When the ball grinding auxiliary agent was sodium hydroxide and the sodium hydroxide/electrolytic manganese residue was 0.3,the compressive strength of the final prepared sample material could reach 17 MPa,and the effect was improved,but it was far lower than the effect of alkali heat treatment.(3)The effects of electrolytic manganese slag base polymer on heavy metals Pb and Cd were studied,and the effects of Pb and Cd addition on the compressive resistance of test material and the toxicity of Pb and Cd leaching in test material were investigated.The results showed that the heavy metal elements Pb and Cd could reduce the compressive strength of the sample material,and the reduction of the compressive strength would increase with the increase of the amount of addition.In a certain range,the base polymer of electrolytic manganese residue can effectively fix Cd,but the fixing effect of Pb is lower than that of Cd,and the compressive strength of the sample material is negatively correlated with the leaching toxicity.The addition of heavy metal increased the leaching toxicity and compressive strength of the sample material.