Hiroshi Satone

Solidification Mechanism of the Sediment Formed by Particle Settling — Analysis of the Final State of the Sediment

Particles in a slurry often form a solidified layer at the bottom of its container, making the slurry no longer useable in material fabrication processes. In order to analyze the mechanism of solidification of a sediment, we observed the gravitational sedimentation behavior of various slurries prepared by changing the slurry pH and measured the height of the solidified layer after settling by inclining the test tube. We conclude that the height of the solidified layer has a close correlation with the maximum repulsive force calculated by the DLVO theory, but not with the potential barrier. In addition, we can express the final height of the solidified layer using a very simple model.

Filtration of waste coolant from fixed-abrasive wire sawing and recycle of retrieved silicon powder for feedstock

For the purpose of this work, several types of waste coolants from fixed-abrasive wire sawing (FAS) were filtrated, and the characteristics of the coolants and the retrieved solid materials were investigated. The all coolants consisted of water and glycol series with the boiling temperature of around 200°C. However, the viscosity of each coolant were different due to the difference in the ratio of coolant components. Experimental results of pressurized filtration can be explained by a rate equation which we proposed. The concentration of diamond in the retrieved solid materials was less than 0.2wt%. Metal contents in the retrieved Si were measured by an inductively coupled plasma mass spectrometry (ICP-MS). The result indicated that quality of the retrieved Si is sufficient for the use as feedstock. The shaped Si was easily melted in a resistance heating furnace. We concluded that the Si powders in waste coolants from FAS can be used as feedstock.

Development of a novel high performance cake-less filtration system

A new cake-less continuous filtration system with a spiral guide rod inserted into a ceramic tube filter and slurry prepared in a well dispersion state has been developed. We tried to filter some difficult to filter materials such as iron oxide and activated sludge. Especially, the algal suspension and activated sludge was not able to be filtrated by a conventional filtration system like filter press. Concentrated slurries of iron oxide and activated sludge were discharged at 35 vol% and 7.55 mass% respectively. The concentrates of every sample retained flowability. In addition, to apply this system to a real process, we tried to calculate the filter tube number from the relationship between the filtration flux and slurry concentration. As a result, the size of this system can be expected to be very compact. Also, in this system, the batch operation was more effective than continuous operation.

Development of a novel high performance continuous cake-less filtration system.

A new cake-less continuous filtration system has been developed for large-scale treatment. Sericite slurries prepared by adding water glass as dispersant were filtered by the developed filtration system. It was shown that a spiral guide rod inserted into a ceramic tube filter is very effective for the cake-less continuous filtration. This system achieves much higher filtration rate compared to a conventional cross-flow filtration and we can collect much denser concentrate continuously without any cake formation.