| Mining industry is the basic industry to promote modern civilization.In the process of mining smelting,a large amount of solid waste will be accumulated,which will cause a series of safety and environmental problems.Tailings is a bulk industrial solid waste with the largest production and accumulation in industrial and mining enterprises,which has a great influence on environmental pollution and ecological landscape.According to the Development Report of China’s Bulk Industrial Solid Waste Comprehensive Utilization Industry(2022),Chinese iron tailings produce the most,accounting for about 40.9% of the total category.The accumulation of iron tailings in the open will be a major drain on land resources,and wind dust will bring about serious air pollution in the mining area,damaging the health of personnel and inhabitants nearby.Consequently,it is essential to create new technologies and materials that can successfully regulate air pollution in open-pit mines and address the issues of tailing reduction and resource utilization.In this paper,iron tailings as raw materials,iron tailings activation treatment after the preparation of environmental dust suppressant,and for the mine interface pollution control application research,in order to achieve the purpose of in-situ materials,waste pollution control.In addition,the accumulation of iron tailings has seriously occupied the soil resources.The research on the utilization of iron tailings has important significance for the rapid restoration of soil ecology,soil resource protection and agricultural development around the mining area.In this study,iron tailings were taken as the research object and activated by mechanochemical coupling activation.Exploring the key factors for enhancing the gelling activity of iron tailings,X-ray diffraction analysis,Fourier infrared spectroscopy analysis,scanning electron microscopy,and other microscopic characterization techniques were employed to investigate the particle characteristics and microstructure alterations.The optimum activation parameters for activating the gelling activity of iron tailings were obtained.A ternary admixture system of iron tailings,industrial solid waste slag powder rich in calcium oxide,alumina,and cement was developed to synergistically react,and the activity index of the system was analyzed to uncover the hydration hardening mechanism of iron tailings.The composite utilization of iron tailings based cementite material is applied to the interface pollution control of open tailings yard according to local conditions.The experimental results show that:(1)By studying the activation effects of mechanical activation and chemical-mechanical coupling activation on iron tailings,it is found that the mechanical-chemical coupling activation can effectively activate the potential gelling activity of iron tailings.Raw iron tailings have low activity and can not be used as cementing material directly.The feasibility of activated iron tailings as cementing material was investigated through a combination of mechanical vibration grinding and chemical activation,thereby exploring their activation technology.The results show that the specific surface area and crystallinity of iron tailings can be increased by mechanical activation,and the particle size distribution D90 of iron tailings decreases from 38.547μm to 16.588μm after 20 s mechanical vibration grinding.The effect of chemical-mechanical coupling activation is better than that of single mechanical activation.When a single component of activated iron tailings is used as the concrete admixture of 30%,its 28 d compressive strength activity index can reach up to 81.7%,and it has pozzolash activity.It is mixed with desulfurized gypsum at 8:2 for curing for 7 days and immersed in water for 3 days.Can be judged as active mixed material.XRD,FT-IR and SEM were used to analyze the activation mechanism of iron tailings from the microscopic point of view.Mechanical force activation weakens the X-ray diffraction peak of iron tailings particles,damaging their internal crystal structure and deepening the amorphous degree.An infrared spectrum test reveals that mechanical vibration grinding causes the disordered substances on the powder’s surface to rise,leading to crystal lattice deformation and dislocation of iron tailings,thus creating an unstable crystal structure.This,in turn,increases vibration energy and boosts the activity of iron tailings.(2)The hydration hardening mechanism of iron tailings based cementitious material was investigated,and a compound with a compressive strength of over 80%was created.The utilization theory of synergism and complementarity led to the conclusion that the cementing material was composed of iron tailings,slag powder,and cement clinker.To evaluate the compressive strength of the iron tailings-based cementing material,a great many experiments were conducted to determine the effects of alkali activator type and dosage,iron tailings dosage,water-binder ratio,and curing age.In this paper,the ratio composition of the cementitious system with high content of iron tailings was studied.An orthogonal experimental design yielded the most desirable cementitious material ratio,consisting of 83.5% iron tailings,11% slag powder,and 5.5% clinker.The sodium silicate solution with modulus 1.8 was used as the alkali activator,and the dosage was 6% of the total mass of the system.The results show that C-S-H gel and C-A-S-H gel are produced in the hydration reaction.The amorphous gel formed by the reaction bonded with ettringite,forming a dense three-dimensional network structure.It is also found that the water binder ratio is negatively correlated with the compressive strength of the consolidated body.The developed cementing material with high content of iron tailings also has a certain compressive strength(5.4MPa)at a high water-binder ratio(0.55).The Good slurry fluidity and compressive strength of crust-type dust suppression material provide a good foundation for the application of interface pollution control technology in the later stage.(3)Iron tailings based crust-type dust suppression material has good wind erosion resistance in interface pollution control.The dust suppression material prepared with the optimal ratio and appropriate water binder ratio can be rapidly consolidated after spraying on the surface of naturally air-dried tailings sand and gravel.The crusts have good mechanical properties,excellent waterproof and freeze-thaw resistance,wind erosion resistance rate of more than 99%,and sustainable dust suppression for more than 8 months,so as to achieve the purpose of waste pollution control. |
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