X-ray fluorescence analyzer and a method for performing an x-ray fluorescence analysis

Patent metadata

Field	Value
Publication number	US-11815480-B2
Application number	US-201817049256-A
Country	US
Kind code	B2
Filing date	Apr 20, 2018
Priority date	Apr 20, 2018
Publication date	Nov 14, 2023
Grant date	Nov 14, 2023

Abstract

An X-ray fluorescence analyzer comprises an X-ray tube for emitting incident X-rays in the direction of a first optical axis. A slurry handling unit is configured to maintain a constant distance between a sample of slurry and the X-ray tube. A first crystal diffractor is located in a first direction from the slurry handling unit, and configured to separate a predefined first wavelength range from fluorescent X-rays that propagate into the first direction. It is configured to direct the fluorescent X-rays in the separated predefined first wavelength range to a first radiation detector. The input power rating of said X-ray tube is at least 400 watts. The first crystal diffractor comprises a pyrolytic graphite crystal. The optical path between said X-ray tube and the slurry handling unit is direct with no diffractor therebetween.

First claim

The invention claimed is:

1. An X-ray fluorescence analyzer, comprising:
an X-ray tube for emitting incident X-rays in a direction of a first optical axis,
a first radiation detector,
a slurry handling unit configured to maintain a constant distance between a sample of slurry and said X-ray tube,
a first crystal diffractor located in a first direction from said slurry handling unit, said first crystal diffractor being configured to separate a predefined first wavelength range from fluorescent X-rays that propagate into said first direction, and configured to direct the fluorescent X-rays in the separated predefined first wavelength range to said first radiation detector, wherein:
the X-ray tube has an input power rating of at least 400 watts,
the first crystal diffractor comprises a pyrolytic graphite crystal,
an optical path between said X-ray tube and said slurry handling unit is direct with no diffractor therebetween, and
said slurry handling unit comprises a sample chamber having a sample window in a wall of said sample chamber for allowing X-rays to pass through while keeping said sample of slurry within said sample chamber.

2. The X-ray fluorescence analyzer according to claim 1 , wherein:
the X-ray tube comprises an anode for emitting said incident X-rays, and
said slurry handling unit is configured to maintain a shortest linear distance that is shorter than 50 mm between said sample of slurry and said anode.

3. The X-ray fluorescence analyzer according to claim 2 , wherein said X-ray tube is an end window type X-ray tube.

4. The X-ray fluorescence analyzer according to claim 1 , wherein the input power rating of said X-ray tube is at least 1 kilowatt.

5. The X-ray fluorescence analyzer according to claim 1 , wherein a diffractive surface of said pyrolytic graphite crystal is one of the following:
a simply connected surface curved in one direction;
a simply connected surface curved in two directions; and
a rotationally symmetric surface that is not simply connected.

6. The X-ray fluorescence analyzer according to claim 1 , wherein the first crystal diffractor comprises:
a first slit on a first optical path between said slurry handling unit and said pyrolytic graphite crystal, and
a second optical path between said pyrolytic graphite crystal and said first radiation detector.

7. The X-ray fluorescence analyzer according to claim 6 , wherein:
a diffractive surface of said pyrolytic graphite crystal is curved in one direction only, with a radius of curvature in a plane defined by said first optical path and said second optical path, and
said first slit comprises or consists of a linear slit oriented perpendicular against said plane.

8. The X-ray fluorescence analyzer according to claim 1 , wherein:
said slurry handling unit is configured to maintain a planar surface of said sample of slurry on a side facing said X-ray tube, and
said first optical axis is perpendicular against said planar surface.

9. The X-ray fluorescence analyzer according to claim 1 , wherein:
said slurry handling unit is configured to maintain a planar surface of said sample of slurry on a side facing said X-ray tube, and
said first optical axis is at an oblique angle against said planar surface.

10. The X-ray fluorescence analyzer according to claim 9 , wherein said first crystal diffractor is located at a rotational angle around said first optical axis, at which said planar surface of said sample of slurry covers a largest portion of a field of view of the first crystal diffractor.

11. The X-ray fluorescence analyzer according to claim 1 , further comprising:
a plurality of other radiation detectors in addition to said first radiation detector, and
a plurality of other crystal diffractors in addition to said first crystal diffractor, each of said first crystal diffractor and said plurality of other crystal diffractors being located at a respective rotation angle around said first optical axis, and each of said first crystal diffractor and said plurality of other crystal diffractors being configured to separate a predefined wavelength range from the fluorescent X-rays that propagate into a respective direction, and configured to direct the fluorescent X-rays in the respective separated predefined first wavelength range to a respective radiation detector of said first radiation detector and said plurality of other radiation detectors.

12. The X-ray fluorescence analyzer according to claim 11 , further comprising:
a second radiation detector;
wherein:
said plurality of other crystal diffractors comprises a second crystal diffractor comprising a second crystal, the second crystal diffractor being configured to direct the fluorescent X-rays in a respective separated second predefined wavelength range to said second radiation detector,
said second crystal comprises or consists of a material other than pyrolytic graphite, and
said first crystal diffractor and said second crystal diffractor are configured to direct to their respective radiation detectors characteristic fluorescent radiation of a same element.

13. The X-ray fluorescence analyzer according to claim 12 , wherein said second crystal comprises or consists one of:
a silicon dioxide crystal,
a lithium fluoride crystal,
an ammonium dihydrogen phosphate crystal, and
a potassium hydrogen phthalate crystal.

14. The X-ray fluorescence analyzer according to claim 12 , wherein said second radiation detector comprises or consists of a gas-filled proportional counter.

15. The X-ray fluorescence analyzer according to claim 12 , wherein said element is gold.

16. The X-ray fluorescence analyzer according to claim 1 , wherein the first radiation detector has an energy resolution better than 300 eV at a reference energy of 5.9 keV.

17. The X-ray fluorescence analyzer according to claim 1 , further comprising:
an analyzer body,
a front wall of said analyzer body,
an opening in said front wall, and
a holder for removably holding said slurry handling unit against an outer side of said front wall and aligned with said opening in said front wall.

18. The X-ray fluorescence analyzer according to claim 17 , wherein said X-ray tube and said first crystal diffractor are both inside said analyzer body, on a same side of said front wall.

19. The X-ray fluorescence analyzer according to claim 1 , further comprising:
a filter plate on the optical path between said X-ray tube and said slurry handling unit.

20. The X-ray fluorescence analyzer according to claim 19 , wherein said filter plate is located closer to said X-ray tube than to said slurry handling unit.

21. The X-ray fluorescence analyzer according to claim 1 , further comprising:
a calibrator plate; and
an actuator configured to controllably move said calibrator plate between at least two positions, of which a first position is not on a path of the incident X-rays and a second position is on the path of the incident X-rays and in a field of view of the first crystal diffractor.

22. The X-ray fluorescence analyzer according to claim 1 , wherein said first radiation detector comprises or consists of a solid-state semiconductor detector.

Assignees

• Outotec Finland Oy

Inventors

• Koskinen Tommi
• Pelli Antti
• Sipilä Heikki

Classifications

• G01N33/24

  Earth materials (G01N33/42 takes precedence) · CPC title

• B03B13/06

  using absorption or reflection of radioactive emanation · CPC title

• G01N23/223 Primary

  by irradiating the sample with X-rays or gamma-rays and by measuring X-ray fluorescence · CPC title

• G21K1/06

  using diffraction, refraction or reflection, e.g. monochromators (G21K1/10, G21K7/00 take precedence) · CPC title

• G01N2223/076

  X-ray fluorescence · CPC title