Preparation And Performance Of 3D Printable Building Materials From Copper/Iron Tailings

The tailings discharged during the mineral smelting process of iron ore and copper mines are the main sources of pollution in the mining area and occupy a large amount of land.Therefore,it is urgent to carry out comprehensive utilization of tailings in order to protect the surrounding environment and land resources.In this paper,copper tailings and iron tailings were taken as research objects,and copper /iron tailings cemented composite materials were prepared.The experimental results show that the FC7 sample is the best design for 3D printable building material,copper tailings and iron tailings have the best compounding effect on mechanical properties at a mass ratio of 1:4.The FC7 sample has a fluidity of 197.5 mm,and its initial and final setting times are 50 minutes and 82 minutes,respectively.After 28 days of FC7 samples under laboratory conditions,the flexural strength and compressive strength were 8.2 MPa and 45.2 MPa,respectively.The microstructure of the copper / iron tailings cemented composites was characterized by XRD,FTIR and other analytical methods.The results show that the hydration products of copper / iron tailings cemented composites are mainly ettringite and C-S-H gel,which help to increase strength.The ettringite,C-S-H gel and other gel crystals form a complex three-dimensional network structure,which makes the matrix more dense,which in turn enhances the mechanical properties of the copper / iron tailings cemented composite material.The FC7 sample’s internal and external exposure index values were 0.303 and 0.475,far below 1.0 for the main building materials,which indicates that the copper/iron tailings cemented composite material can meet the requirements of the Chinese standard GB 6566-2010.Therefore,copper/iron tailings are safe and free of radioactive contamination.The leaching concentrations of Ba,Cu and Zn in FC7 samples were 0.2185,0.0486 and 0.2620 mg/L,which were far below the drinking water quality limit specified in GB 5749-2006.This shows that the developed copper/iron tailings cemented composite material is environmentally friendly.A pilot test study was carried out using a truss building 3D printer,a structural test piece was prepared with copper/iron tailings cemented composite materials,and the 28-day splitting tensile strength was 3.54 MPa and the compressive strength was36.99 MPa.The flexural strength is 5.12 MPa.It also printed houses,rockery and background walls.These printing jobs initially verified the feasibility of the application of copper/iron tailing cementitious composite materials in architectural3 D printing from the aspects of good processability and mechanical properties.The copper tailings and iron tailings used in this article only require freight,which greatly reduces the cost of construction materials and treats solid waste,protects the environment,and has good application prospects.