US 6,983,060 B1
Method to measure degree and homogeneity of alumina calcination
Valerie Martinent-Catalot, Gardanne (France); Jean-Michel Lamerant, Bouc-Bel-Air (France); and Bernard Rouit, Marseilles (France)
Assigned to Aluminium Pechiney, Paris Cedex (France)
Appl. No. 10/130,260
PCT Filed Nov. 21, 2000, PCT No. PCT/FR00/03227
§ 371(c)(1), (2), (4) Date Jul. 29, 2002,
PCT Pub. No. WO01/38855, PCT Pub. Date May 31, 2001.
Claims priority of application No. 99 14951 (FR), filed on Nov. 26, 1999.
Int. Cl. G06K 9/00 (2006.01); G01N 21/25 (2006.01); G01N 33/20 (2006.01); G01N 37/00 (2006.01)
U.S. Cl. 382—100 6 Claims
OG exemplary drawing
 
6. In a process for producing calcined alumina comprising sampling the calcined alumina to determine degree and homogeneity of calcination,
the improvement comprising measuring the degree and homogeneity of the calcination utilizing an image analysis device equipped with a sensitive camera in a spectral analysis window corresponding to a wavelength range equal to or in the vicinity of visible light and comprising the steps of:
a) mixing alumina under analysis in a liquid wherein the refractive index is, in said wavelength range, between the refractive index of a lightly calcined alumina and the refractive index of a strongly calcined alumina;
b) preparing a slide for observation of said mixture in said image analysis device, said mixture being illuminated by stable polychromatic radiation compatible with said spectral analysis window;
c) receiving an image by the camera and processing a signal resulting in the definition of an image composed of a given number of pixels with three calorimetric components; and
d) statistically processing said pixels using their calorimetric components and determining the calcination degree and the homogeneity of the calcination.