Evaluation of the Effect of Operating Parameters on the Performance of Orifice/Porous Pipe Type Micro-bubble Generator

At present, the good classification index has been achieved by anionic reverse flotation technology for the Anshan hematite, but the grade of the tailing is still high. The main reason is that the fine useful minerals can not be recovered effectively .According to the advantages of the packed flotation column, the reverse flotation tests of a hematite were conducted using the packed micro-bubble contacting flotation column. Based on the conditional tests of flotation column operating parameters and the pharmaceutical system, an iron concentrate with TFe grade of 67.05% was obtained and the grade of tailings was 11.25%.

Download Full-text

Application of Improved Voltage Compensation in the SEM to Imaging of Organic Materials

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100072666 ◽

1973 ◽

Vol 31 ◽

pp. 444-445

Author(s):

P.J. Killingworth ◽

M. Warren

Keyword(s):

Electron Beam ◽

Organic Materials ◽

Operating Parameters ◽

Low Density ◽

Beam Diameter ◽

Incident Electron Beam ◽

Specimen Material ◽

Voltage Compensation ◽

Selection Of ◽

Scanning Electron

Ultimate resolution in the scanning electron microscope is determined not only by the diameter of the incident electron beam, but by interaction of that beam with the specimen material. Generally, while minimum beam diameter diminishes with increasing voltage, due to the reduced effect of aberration component and magnetic interference, the excited volume within the sample increases with electron energy. Thus, for any given material and imaging signal, there is an optimum volt age to achieve best resolution.In the case of organic materials, which are in general of low density and electric ally non-conducting; and may in addition be susceptible to radiation and heat damage, the selection of correct operating parameters is extremely critical and is achiev ed by interative adjustment.

Download Full-text

Electron sources: Past, present, and future

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100149659 ◽

1993 ◽

Vol 51 ◽

pp. 764-765

Author(s):

David C Joy

Keyword(s):

Glass Tube ◽

Source Size ◽

Electron Gun ◽

Operating Parameters ◽

Operational Parameters ◽

Electron Sources ◽

Difficult Decision ◽

Probe Size ◽

Wide Range ◽

Overall Performance

The electron source is the most important component of the Scanning electron microscope (SEM) since it is this which will determine the overall performance of the machine. The gun performance can be described in terms of quantities such as its brightness, its source size, its energy spread, and its stability and, depending on the chosen application, any of these factors may be the most significant one. The task of the electron gun in an SEM is, in fact, particularly difficult because of the very wide range of operational parameters that may be required e.g a variation in probe size of from a few angstroms to a few microns, and a probe current which may go from less than a pico-amp to more than a microamp. This wide range of operating parameters makes the choice of the optimum source for scanning microscopy a difficult decision.Historically, the first step up from the sealed glass tube ‘cathode ray generator’ was the simple, diode, tungsten thermionic emitter.

Download Full-text