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

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.