X- and γ-Ray techniques for determination of the ash content of coal

Claim 1

A measuring apparatus for quantitative determination of the concentration of ash in coal or coke, which apparatus comprises at least two X-ray or γ-ray scatter assemblies. and means to compute said ash concentration from the outputs of said assemblies, the geometries of said assemblies each being arranged so that the detected X-ray or γ-ray intensity is a measure over substantially the same amount by volume of coal or coke sample, said assemblies each comprising an X-ray or γ-ray source, an energy-sensitive detector to detect scattered X-rays or γ-rays resulting from scattering in the coal or coke of X-ray or γ-rays from said source, an electronic analyzer associated therewith to select all or one or more parts of the detected X-ray or γ-ray spectrum as output from said assemblies, and shielding means for reducing the intensity of direct X-rays or γ-rays, said shielding means being specifically chosen to collimate partly the beam of X-rays or γ-rays in such way as to ensure maximized matched volumes and deep penetration in the coal or coke, and wherein the energy of the X-rays or γ-rays emitted by said assemblies differs from each other.

Claim 7

A method of analyzing coal or coke comprising determining the concentration of ash or mineral matter in coal or coke by the steps comprising measuring the scatter of X-rays or γ-rays of a first energy chosen such that there is a significant difference in absorption of radiation per unit weight in coal matter and mineral matter excluding iron, in combination with either or both of (a) effecting at least one further measurement of scatter of X-rays or γ-rays at a different energy so chosen that there is a significant difference in absorption of radiation per unit weight of coal matter and mineral matter and that the relative absorption per unit weights by said coal matter and said mineral matter at any one energy is significantly different from the relative absorption at each other energy including said first energy, (b) effecting a measurement of the bulk density or mass per unit area of the coal or coke by measuring the backscatter or scatter-transmission respectively of X-rays or γ-rays at an energy chosen such that there is no significant difference in absorption of radiation per unit weight in coal matter and mineral matter, and wherein the detected X-ray or γ-ray intensity is, measured using scatter assemblies which detect radiation from maximised matched volumes.

Claim 8

A method of analyzing coal or coke comprising determining the concentration of ash or mineral matter in coal or coke by the steps comprising measuring the scatter of X-rays or γ-rays of a first energy chosen such that there is a significant difference in absorption of radiation per unit weight in coal matter and mineral matter excluding iron, in combination with either or both of (a) effecting at least one further measurement of scatter of X-rays or γ-rays at a different energy so chosen that there is a significant difference in absorption of radiation per unit weight of coal matter and mineral matter and that the relative absorption per unit weights by said coal matter and said mineral matter at any one energy is significantly different from the relative absorption at each other energy including said first energy, (b) effecting a measurement of the bulk density or mass per unit area of the coal or coke by measuring the backscatter or scatter-transmission respectively of X-rays or γ-rays at an energy chosen such that there is no significant difference in absorption of radiation per unit weight in coal matter and mineral matter, and wherein the detected X-ray or γ-ray intensity is, measured using scatter assemblies which detect radiation from maximised matched volumes.