High-precision fracture control technology for recycling and treatment of solid wastes

The contents of this study are summarized as follows:

Artificial cement paste samples including mineral grains were disintegrated by ED, particle size distribution and the liberation degree of products were analyzed using sieving and image analysis system. The effect of seismic velocity, conductivity, and dielectric constant on the particle size distribution and the liberation degree were investigated. In order to investigate the fracture patterns in the samples subjected to high voltage pulse, the microstructure of the samples was visualized as 3-D image by using microfocus X-ray computed tomography (CT) system before and after the ED tests. The fracture patterns were simulated by using the dynamic fracture process analysis of rock. It was revealed that the fracture patterns varied between dynamic and quasi-static fracture. Influence of the input voltage, P-wave velocity, and dielectric constant on the fracture patterns in ED tests was discussed. The purpose of this study is to develop a fracture and fragmentation control technique using high voltage e lectrical pulse and dynamic fracture process analysis for general-purpose mineral processing.

The contents of this study are summarized as follows:

Model experiments using charge holes and a notched guide hole were performed to visualize the crack propagations around the guide hole. To identify the initiation of the charge and the arrival of the incident wave at the free surface of a model, an ionization gage was installed at the base of the charge and the strain gauges were used. The experimental setup using a high-speed digital video camera system, which was utilized on a notched hole between two charged holes, was used. The framing rate of the video can be varied from 30 to 40,500 frames per second. Influence of the initiation time lag on the crack propagation between two charge holes was discussed and the effect of a guide hole on fracture control was examined. The crack propagations in the PMMA plates considering different distances between the charge holes and initiation times were simulated by dynamic fracture process analysis. The strength prosperities of PMMA subjected to the detonation of explosive were also estimated using the experimental and numerical results. The dynamic fracture processes relating to crack-propagation control in blasting were discussed. The purpose of this study is a development of advanced controlled blasting technique for partial removing from concrete structures and rock excavation with minimized damage around the remaining rock.