This invention relates to a method and an apparatus for measuring the moisture content of bulk material in grain or lump form utilizing the scattering and absorption of radiation.
Control of moisture in a bulk material, for example, coke or sinter mix materials used in the steel industry is indispensible for the successful production of steel of good quality, since the coke ratio and the quality of the steel are dependent upon how the moisture content is controlled. For this purpose, a moisture meter or gauge of the scattering type utilizing the scattering of neutrons has hitherto been widely used for the measurement of the moisture content.
It is known that, in a method of moisture measurement in which the scattering of neutrons is only resorted to for the measurement of the moisture content of a bulk material, the rate of scattering of neutrons is affected not only by the moisture content of the bulk material, but also by the bulk density of the bulk material. The bulk density varies depending on the grain size distribution or moisture distribution of the bulk material, and it is therefore impossible to measure the actual bulk density. U.S. Pat. No. 3,786,251 discloses a method which reduces the influence of the bulk density on the measurement of the moisture content of a bulk material. In this U.S. patent, gamma radiation is employed in addition to the neutrons, and the measured value of gamma radiation is used to compensate the measured value of neutrons so as to reduce the influence of the bulk density on the result of moisture content measurement.
However, due to the fact that a neutron detector and a gamma detector are provided independently of each other in the system disclosed in U.S. Pat. No. 3,786,251, and the position measured by the neutron detector differs from that measured by the gamma detector, the value of the moisture content obtained by compensation has not always been accurate.