Study On The Preparation Of Non-Sintered Tailing Brick With Bayer Red Mud Based Geopolymer Cementitious Materials

Red mud is red sludge residue discharged during the production of alumina.Due to the production of alumina,the amount of red mud produced is increasing.The composition of red mud is difficult to use and causes a large stockpile.This not only consumes a lot of management costs,but also causes environmental pollution,which may threaten the survival of humans.This article was completed with the support of the National Natural Science Foundation of China(51978353).This article used Bayer's red mud as the main ingredient.Preparation of red mud-based highly active powder using petroleum coke residue,calcium carbide slag and high belite cement to modify red mud powder.The composite powder was treated using thermal activation,mechanical activation and chemical activation.Next,added auxiliary materials to prepare the geopolymer.Based on this,the properties of geopolymer cementitious materials with different ages,curing systems,water cement ratios and ash sand ratios were studied.Finally,unsintered tailings bricks were prepared using a red mud based geopolymer.The main contents include the following aspects:(1)By adding 40% petroleum coke to the Bayer red mud powder,good excitation strength can be obtained.The compressive strength of mortar 28 d is 9.5MPa.Calcium carbide slag has a low effect on the red mud modification of the Bayer method.The calcium carbide slag and petroleum coke slag composite modified Bayer red mud can get better strength.The mass ratio of red mud powder,petroleum coke slag and calcium carbide slag was 7:2:1.The compressive strength of mortar 28 d was 11.0MPa.(2)Mixing Bayer red mud,petroleum coke residue and calcium carbide residue for calcination.After calcination at 600? for 180 minutes,the compressive strength of the mortar 28 d was as high as 27.0 MPa.Compared four kinds of auxiliary gelling materials:high belite cement,ordinary Portland cement,fly ash and slag.The combination of slag and Bayer process red mud powder can obtain early strength and stable late strength.The mass ratio of Bayer's red mud powder,slag,petroleum coke and calcium carbide slag was 49:30:14:7.The compressive strength of mortar 28 d was 22.4 MPa.(3)Red mud,slag,petroleum coke slag and calcium carbide slag were mixed at a ratio of 49: 30: 14: 7 as a gelling material,and a red mud base polymer was prepared according to the gel sand test.The compressive strength of the prepared red mud-based geopolymer mortar increases with time.1d compressive strength can reach 63% of 28 d compressive strength,3d compressive strength reaches 71% of 28 d strength,and 7d compressive strength reaches 84% of 28 d strength.The 28 d compressive strength of the soaked and sealed test specimens was higher than 26.0 MPa.The water-cement ratio of the mortar sample has a great influence on the compressive strength.The 28 d compressive strength of the test piece having a water-cement ratio of 0.4 was 35.1 MPa.The compressive strength of the 28 d mortar sample with a sand-to-cement ratio of 1:1and a water-cement ratio of 0.3 was 43.4 MPa.Reducing the amount of slag will result in a decrease in the strength of the mortar.(4)Non-fired bricks were prepared using Bayer's red mud base polymer.It was finally determined that the red mud in the cementitious material was 49%,petroleum coke residue was 14%,calcium carbide residue was 7%,slag was 30%,the gel sand ratio was 1: 3,and the water-gel ratio was 0.5.The 28-day compressive strength of the prepared red mud-based non-sintered tailings brick is 21.8 MPa.The water absorption was 8.4%,and the dry shrinkage value was 0.05%.After 4 days of soaking in water,the strength did not decrease.After 25 freeze-thaw cycles,the mass loss was 0% and the strength loss was 9.05%.All properties meet the requirements of MU15 grade in "Non-sintered Garbage Tailings Brick"(JC / T422-2007).The unsintered tailings brick was prepared using Bayer red mud,petroleum coke,calcium carbide slag,slag and river sand.Red mud did not require high-temperature calcination and addition of chemical reagents to obtain better performance non-fired bricks.The consumption of large amounts of red mud has promoted the development of the aluminum industry and increased the potential economic value of red mud.