Outokumpu Oy

Georg C Von Alfthan

Seppo J Uusitalo

Heikki J Sipila

Antti I Ahonen

Erkki Sakari Kiuru

Tor S Andersson

Lasse S Kahara

Tuula A Lukander

Pekka Rautala

Vaino A Paukku

The invention relates to a measuring cell (1) designed for measuring the contents of the components present in slurries which are in a flowing motion, the measuring cell comprising an inlet pipe (2) and an outlet pipe (9) for the slurry and a measuring window (3). According to the invention, the inlet pipe (2) is placed at a given distance from and in an inclined position with respect to the plane contained in the measuring window (3), in order to direct the slurry jet entering from the inlet pipe (2) to a point that is approximately one internal radius of the inlet passage (2) in front of the center of the measuring window (3).

Measuring cell

The average particle size for particles distributed in a slurry is determined by transmitting at least one beam of ultrasonic rays of a certain frequency into the slurry, detecting, by separate detector means, on one hand ultrasonic radiation that passes through the slurry and, on the other hand, ultrasonic radiation scattered in the slurry, said detector means forming first and second signals corresponding to the intensities of the passed-through and the scattered radiation respectively, determining the scattering attenuation factor on the basis of said first and second signals and the total attenuation factor by using the intensity of passed-through radiation obtained with pure water, and determining the particle size with the help of the scattering attenuation factor, whereby the radio of said factor and the total attenuation factor is formed in order to eliminate influence of the slurry density. Two transmitters operating at different frequencies may be used, whereby one detector may detect passed-through radiation at one frequency and the other detector may detect scattered radiation at the other frequency.

Method and apparatus for the determination of the average particle size

The invention provides an apparatus for measuring the concentrations of elements in a material sample by the capture gamma method, said apparatus including a neutron source in the form of an isotope source or a neutron generator, a moderator surrounding the neutron source and being at least partly constituted by heavy water, a semiconductor detector serving as gamma radiation detector and positioned in the immediate vicinity of the material to be analyzed and in the flux of slow neutrons, so much of the moderator being provided before the detector that this is reached only by a very low number of fast neutrons that have a damaging effect upon the detector. The material itself can form part of the moderator and also graphite is preferably used as a moderator around said heavy water. Furthermore, a body of bismuth having the shape of a cone or a double cone is preferably positioned in front of the neutron source so as to absorb gamma radiation and to scatter fast neutrons.

Apparatus for measuring the concentrations of elements in a material by

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Espoo, Finland

Georg C Von Alfthan