Method and apparatus for measuring incombustible content of coal mine dust using gamma-ray backscatter

Claim 2

Apparatus for measuring the incombustible content of particulate material using a radiation backscatter technique comprising container means for holding a sample of the particulate material, said container means having first and second angularly oriented walls defining first and second angularly oriented surfaces of the sample; first and second radiation source assembly means disposed on opposite sides of said container for producing low energy incident beams through said first wall of said container means at the first surface of the sample; and radiation detector means disposed adjacent said second wall of said container means for detecting backscattered radiation from the second surface of the sample whereby variations in scattered radiation caused by variations in density of the sample are compensated by variations in attenuation of said incident radiation beam and said backscattered radiation.

Claim 3

Apparatus as recited in claim 1 wherein said radiation source means produces a gamma-ray incident beam and said radiation detector means detects gamma-ray backscatter.

Claim 4

Apparatus as recited in claim 1 wherein said radiation detector means defines a subtending detection cone intersecting said incident radiation beams at said scattering volume whereby error from moisture content and non-homogeneous packing of the sample is minimized.

Claim 5

Apparatus as recited in claim 3 wherein each of said source assemblies has a housing shield producing a line incident radiation beam.

Claim 6

Apparatus as recited in claim 4 wherein each of said incident radiation beams is tightly collimated and said detection cone is tightly collimiated.

Claim 7

Apparatus as recited in claim 1 wherein said incident radiation beam is tightly collimated, and said radiation detector means has a tightly collimated detection cone.

Claim 8

Apparatus as recited in claim 6 wherein said radiation detector means includes a housing shield having a conical end subtending said tightly collimated detection cone.

Claim 9

Apparatus as recited in claim 1 wherein said container means has a cup-like configuration with a side wall defining said first wall and a bottom defining said second wall.

Claim 10

Apparatus as recited in claim 8 wherein said container means is a polystyrene cup.

Claim 11

An instrument for measuring incombustible content of coal mine dust in situ using a gamma-ray backscatter technique comprising an instrument housing having a top wall with container support means recessed therein having angularly oriented bottom and side wall means for receiving a container holding a sample of the coal mine dust; gamma-ray source means arranged in said housing on opposite sides of said side wall means for producing tightly collimiated incident gamma-ray beams intersecting within said side wall means; gamma-ray detector means arranged in said housing below said bottom wall means subtending a tightly collimated detection cone intersecting said incident gamma-ray beams within said bottom and side wall means to define a scattering volume in the coal mine dust sample, said gamma-ray detector means detecting gamma-ray backscatter and supplying an output corresponding thereto; and circuit and display means receiving said output from said gamma-ray detector means and providing a display of the incombustible content in the coal mine dust sample, the arrangement of said gamma-ray source means and said gamma-ray detector means being such that said scattering volume is located at a depth within the coal mine dust sample to permit variations in scattered radiation caused by variations in sample density to be compensated by variations in attenuation of said incident gamma-ray beams and said gamma-ray backscatter.

Claim 12

An instrument for measuring incombustible content of coal mine dust in situ using a gamma-ray backscatter technique comprising an instrument housing having a top wall with container support means recessed therein having angularly oriented bottom and side wall means for receiving a container holding a sample of the coal mine dust; gamma-ray source means arranged in said housing on opposite sides of said side wall means for producing tightly collimiated incident gamma-ray beams intersecting within said side wall means; gamma-ray detector means arranged in said housing below said bottom wall means subtending a tightly collimated detection cone intersecting said incident gamma-ray beams within said bottom and side wall means to define a scattering volume in the coal mine dust sample, said gamma-ray detector means detecting gamma-ray backscatter and supplying an output corresponding thereto; and circuit and display means receiving said output from said gamma-ray detector means and providing a display of the incombustible content in the coal mine dust sample, the arrangement of said gamma-ray source means and said gamma-ray detector means being such that said scattering volume is located at a depth within the coal mine dust sample to permit variations in scattered radiation caused by variations in sample density to be compensated by variations in attenuation of said incident gamma-ray beams and said gamma-ray backscatter.

Claim 13

An instrument as recited in claim 10 wherein said container support means includes a cup-like outer support and an inner liner.

Claim 14

An instrument as recited in claim 11 wherein said circuit and display means includes an analog meter.

Claim 15

An instrument as recited in claim 10 wherein gamma-ray source means includes a pair of source assemblies producing line incident gamma-ray beams.

Claim 16

An instrument as recited in claim 10 wherein said container support means has a cup-like configuration and further comprising a polystyrene cup for holding a coal mine dust sample and adapted to be received in said container support means.

Claim 19

A method as recited in claim 15 wherein said directing step including directing a plurality of low energy, incident gamma-ray beams at the first surface of the sample from various positions around the container.

Claim 20

A method as recited in claim 16 and further comprising the step of screening the coal mine dust sample before filling the container.