Measuring and testing – Volume or rate of flow – By measuring thrust or drag forces
Reexamination Certificate
2002-01-31
2004-07-20
Patel, Harshad (Department: 2855)
Measuring and testing
Volume or rate of flow
By measuring thrust or drag forces
Reexamination Certificate
active
06763732
ABSTRACT:
The present invention relates to an arrangement for measuring material flow, particularly concentrate flow, in connection with a flotation cell.
In connection with flotation cells, the measuring of the quantity of flotation concentrates has been difficult, owing to the air content of said concentrates, among others. Conventional quantity meters, such as the V-dam measuring, have turned out to be unreliable when used in connection with flotation cells. In the drain pipe, located in succession to the drain chute, the slurry and liquid, formed of the foam of flotation cells and having different densities, are typically at least partly in layers, which has made the reliable measuring of mass flow more difficult. Indirect calculatory methods have likewise proved to be either unreliable or else there is too much delay for a rapid adjusting of the operation of the flotation cell.
The object of the invention is to realize a completely new arrangement for measuring the mass flow of flotation concentrate, whereby the drawbacks of the prior art can be avoided.
The arrangement according to the invention is characterized in that the arrangement comprises an elongate sensor element that extends essentially over the whole transversal area of the material flow to be measured, and a measuring device for detecting the position of the sensor element.
According to a preferred embodiment of the invention, the measuring device is an angle transmitter. A preferred embodiment of the invention is characterized in that the sensor element is attached to the horizontal axis of the measuring device.
Another embodiment of the invention is characterized in that the horizontal axis of the measuring device is positioned essentially transversally with respect to the flowing direction of the material flow to be measured. The material flow to be measured is advantageously the material flow that flows out of the flotation cell via a drain chute. In a preferred embodiment, the arrangement is provided in connection with the drain chute of a flotation cell, preferably so that the sensor element is at least partly located in the collecting pipe.
The arrangement is typically connected to the control system of the flotation cell. Advantageously the arrangement comprises a display unit. In a preferred embodiment, the sensor element is provided with a calibration means, such as a movable weight.
The arrangement according to the invention has several remarkable advantages. The arrangement according to the invention is well suited to be used in connection with flotation cells. The arrangement is secure in operation, simple in structure and easily applied to various different flotation cells. By means of the sensor element arrangement, there is achieved a good measuring reliability, which has been proved by tests that were carried out. The sensor element reacts well to changes in the material flow, and it is not too sensitive to local changes of velocity. Owing to the small area of the sensor element, the force that is directed to the sensor element by lighter materials with a lower density is relatively small in comparison with the force directed to said sensor element by heavier materials with a higher density. Thus the sensor element is well suited to measure the quantities of concentrate flowing out of flotation cells. The information given by the measuring device can easily be applied when controlling the operation of the flotation cell. By means of the calibration means arranged in the sensor element, the arrangement according to the invention can be applied to many different usages, and to measuring material flows with varying characteristics.
In the present specification, the term flotation cell means a unit composed of a flotation mechanism, chutes and tank.
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patent: 6212958 (2001-04-01), Conley
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Forss Mikael
Saastamoinen Eljas
Outokumpu Oyj
Patel Harshad
Smith-Hill and Bedell
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