| Coal gangue is a mixture of rocks that are discharged in the process of rock or coal mining and coal washing in the coal seam.The production of coal gangue in China is huge,and its discharge speed is astonishing.At present,the existing ways of utilization of coal gangue in China are varied.However,due to the problems of cost and immature technology,coal gangue has little resource utilization.Most gangue remains on the surface to form coal gangue hill,which not only causes the waste of land resources,but also brings about a series of eco-environmental problems.Therefore,gangue as a potential available resource is of great significance to preserve in situ and restore vegetation on the stacking site,so as to prevent and control its ecological environment.An important role has low molecular weight organic acid and humic acid in improving soil structure,improve soil fertility and soil pollution remediation.By adding humic acid to the non-weathered coal gangue and the low molecular weight organic acids that are generally secreted by plants,in the simulation of different types and different concentrations of low molecular weight organic acid and humic acid,this experiment sets up different culture time.This paper analyzes the changes of coal gangue particles,chemical properties and nutrient release.The correlation between physical and chemical properties of coal gangue after applying organic acids was analyzed.The difference of availability of different organic acids to plants was compared,and the mechanism of low molecular weight organic acids on physical and chemical properties of coal gangue was discussed.The main conclusions are as follows:(1)By the laser particle size analyzer,the coal gangue for the test is dominated by the powder particle,followed by the coarse sand grade,then to the medium sand grade and the fine sand grade.For the test of low molecular weight organic acid and humic acid applied in coal gangue,the gangue particle size change.Under the control conditions of coal particle size level there is no change,citric acid,tartaric acid treatment of the coal gangue with coarse level increased,application of clay coal gangue malic acid,humic acid increased,little change in the oxalic acid treatment of coal gangue particle electrode.Compared with the control,with the prolongation of culture time,the particle size and particle size increased,while the percentage of smaller sand volume showed a rising trend.The large particle size showed a downward trend.The addition of low molecular weight organic acid and humic acid continuously promoted the refinement of coal gangue particles and the formation of small aggregates.The distribution of each grade of coal gangue and the concentration of organic acid did not form a significant regularity.(2)The effects of different low molecular weight organic acids and humic acids on the p H value of coal gangue are quite different.The overall performance is that citric acid and malic acid treatment can reduce the p H value of coal gangue,while thep H value of coal gangue treated by tartaric acid,oxalic acid and humic acid is increased.Keep the coal gangue in humid environment is helpful to increase its conductivity,and low molecular weight organic acid and humic acid addition on the conductivity of coal gangue played an important role in citric acid and malic acid added to increase the electrical conductivity has a role in promoting,tartaric acid,oxalic acid and humic acid significantly reduced the conductivity of coal gangue.(3)The content of alkali hydrolyzed nitrogen increased significantly compared with the initial content.The application of citric acid and malic acid promoted the release of alkali hydrolyzed nitrogen,and the influence of malic acid was greater than that of citric acid.After adding tartaric acid,oxalic acid and humic acid,the average nitrogen content of coal gangue were lower than the control level,the three kinds of acid nitrogen in coal gangue by alkali release has some inhibitory effect.5 kinds of organic acids,which are kept in the wet state of coal gangue and added to the experiment,have the effect of reducing the content of coal gangue.Organic acids promote the release of available phosphorus in coal gangue.(4)After the coal gangue was soaked in humid,low molecular weight organic acid and humic acid,the p H value and electrical conductivity showed a very significant negative correlation.At the same time,there was a significant correlation between p H value and available nutrients.This indicates that the change of p H value can change the nutrient release of coal gangue to some extent.(5)After the application of five organic acids,the p H mean value of coal gangue ranges from 5.82 to 7.95,this is between weak acid and alkaline.The change of p H value has little effect on plants.Most plants can adapt to this growing environment.The effect of organic acids on coal gangue available nutrients mainly in promoting release of nitrogen in coal gangue,enhance the nutrient level of coal gangue;effect of organic acids on potassium and available phosphorus although on improving nutrient level,but the nutrient content have increased to a certain extent improve the plant growth environment,improve the coal gangue on the growth of plant available capacity. |
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