| The rapid development of the iron and steel industry has led to the rapid development of the iron ore mining industry in China.Chinese iron ore resources reserves is wide,but the poor mainly iron ore and accounted for a total of 97%above,resulting in a large amount of tailings discharge.Restricted by the technology of using iron ore scale,the iron mainly made tailings dam storage at present.According to the statistics of domestic stockpiling of tailings has exceeded 80 million tons,and showed a rising trend.The iron tailings not only caused air pollution,but also endangered the surface water,groundwater and soil environment.There are still dam ecological risk.These have become the bottleneck of sustainable development of iron and steel industry.Therefore,it is particularly important that the scale and high value utilization of iron tailings.At present,although the using of iron tailings by many ways,the amount is low and can not effectively solve the problem of iron tailings.The soil utilization of iron tailings is an effective way to realize scale utilization and increase utilization rate.But the most notable problem of soil utilization of iron tailings is that its physical and chemical properties are very unsuitable for the survival of soil animals and plants.Physical and chemical improvement technology has many advantages,such as simple method,easy popularization,good effect and long timeliness,is a hot topic at home and abroad.In this study,the soil of iron tailings in ANSTEEL GROUP CORPORATION of Dagushan tailings pond as the research object.Through the modifiers of rice husk,biochar,organic fertilizer and soil to improve physical and chemical technology development of iron tailings soil utilization,to solve the technical problems of iron tailings permeability difference,soil water holding fertility is too poor,too strong alkaline soil pH,for engineering application.The results of the study are as follows:(1)By measuring the physical and chemical properties of iron tailings,it is found that the living environment of the soil is very poor.Iron tailings is strongly alkaline,very low content of organic matter,nitrogen,available phosphorus content were much lower than the plant growth standard,soil fertility is extremely low,poor living conditions of biological iron tailings;The iron ore tailings are dominated by sand grains,which have poor water holding and fertilizer retention capacity.The fine sand content exceeds 43.5%,and the tailings are densely packed and have poor air permeability.(2)The effect of single modification of the four modifiers is:for the bulk density and porosity of the tailings matrix,biochar and rice husk have the best improvement effect;for organic matter content,biochar and organic fertilizer have the best improvement effect;for the tailings matrix The acidity and alkalinity of rice husks and organic fertilizers have the best improvement effect.For the moisture content of the tailings matrix,biochar and organic fertilizers have the best improvement effect;mature soil has better improvement effect on all indexes,and is more balanced,but the amount is more.(3)Using the result of single improved experiment,six compound ratio is made to carry on the compound improvement experiment.The formula I was found to be the best when the ratio of rice husk,biochar,organic fertilizer and mature soil is 3:1:1:10.This formula can reduce the bulk density value from 1.57g/cm3 to 1.16g/cm3,the total porosity from 35.29%to 53.04%,capillary porosity from 28.24%to 39.24%,the non capillary porosity from 7.05%to 13.80%.The permeability index has been improved to be within the effective range,indicating that the permeability of the tailings matrix after materialization has been well improved and meet the basic needs of soil and animal growth;The field water capacity increased from 11.28%to 22.60%,the capillary porosity increased from 16.72%to 33.94%,the saturated water content increased from 20.89%to 45.87%,and the water retention index was improved to the effective range.After the tailings matrix water holding capacity has been well improved to meet the basic needs of the growth of soil and animal plants.Organic matter content increased from 3.15g/kg to 13.26g/kg,from the thin sand to the soil standard of intermediate fertility,to meet the soil dynamic.The pH value decreased from 8.72 to 7.64,the alkalinity of the tailings matrix was reduced from the original strong alkaline to alkaline soil,which met the basic needs of most soil and animal growth.(4)In the field test of the project,the physical and chemical properties of the improved tailings basically meet the living conditions of the soils and plants,and the selected plants grow normally.After the material modification,the total porosity of the tailings matrix is maintained at about 52%;the water content is maintained at about 12%,the organic matter content is maintained at about 13 g/kg,and the pH value is maintained at a weakly alkaline state around 7.6,which can be met in the effective range of soil and plant growth.The multicolored dianthus,coriander,and soybean planted grew well,and the highest plant height reached 56.2 cm,86.9 cm,and 81.2 cm,respectively. |
