Experimental Study on Fragmentation and Pulverization Characteristics of Polymetallic Nodules During Lifting
Based on the experimental study on fragmentation and pulverization characteristics of polymetallic nodules in the process of ore lifting,it is found that there is obvious fragmentation of nodules during lifting process.With the volume concentration of 6.5%,the mass percent of polymetallic nodules with particle size larger than 50 mm decreases from 75.58%to 23.78%;with the volume concentration of 15%,the mass percent decreases from 51.51%to 10.08%.Pulverization of nodules was observed in the experiment.With the volume concentration of 6.5%,the mass percent of the polymetallic nodules powder with particle size less than 0.1 mm is 1.79%,and the median particle size is 10.07 μm;with the volume concentration of 15%,the mass percent of polymetallic nodule powder with particle size less than 0.1 mm is 1.99%,and the median particle size of the powder is 9.47 μm.Based on the experimental data,it is estimated that as per mining of 10 million tons of polymetallic nodules,the powder discharge will cause tens of thousands of tons of Fe and Mn losses,as well as hundreds of tons of Co,Ni and Cu losses.Besides,the maximum redeposition thickness of the sediment plume induced by mining is more than 3 mm after diffusion and settlement,which will bring a significant impact to environment.