Neutron Detectors in Mining?

..."In coal exploration programmes, nuclear logging techniques — especially (7-7) and (natural-7) — are essential. In addition, measurement of the ash content of coal by means of low-energy X-ray scattering is well-established. The refinement of neutron techniques promises even more accurate measurement of ash content, continuous measurement of calorific energy and determination of the concentration of important elements such as sulphur, chlorine, silicon, calcium, aluminium, and iron — measurements that are required for controlling the efficiency of special combustion furnaces."...

..."For direct application to investigation of the minerals, isotopic neutron sources, especially 252Cf, 238Pu/Be and 241 Am/Be, are preferred because of their small size and independence from power supplies."...

https://www.iaea.org/sites/default/files/publications/magazines/bulletin/bull24-4/24405384546.pdf

https://inis.iaea.org/collection/NCLCollectionStore/_Public/29/057/29057219.pdf

http://www.innopave.com/en/products/Geotechnical/lab_geotechnical_details.asp?ProductID=219

I think it is referring to neutron activation analysis. Many elements become radioactive when bombarded with neutrons. The radiation given off is analyzed to detect what elements are present.

http://fd93444gjhh4yme418ouow16yt.wpengine.netdna-cdn.com/wp-content/uploads/2016/10/ss_NAAmining_090816-web.pdf

https://www.sciencedirect.com/science/article/pii/S0969804398000712

We've made detectors in the past that looked for diamonds. Neutrons cause diamonds to scintillate & this can be detected through chunks of rock.

https://en.wikipedia.org/wiki/Particle_experiments_at_Kolar_Gold_Fields may interest you.

Yes, and the oil and gas industry have a special segment called wireline logging. (been there - done that for 11 years) Coal formations often appeared on oil well logs. I can imagine the coal companies have picked up on this.

We used a plutonium 238 source with beryllium mixed in the source to bombard rock formations with high energy neutrons and then our instrument would detect "thermal neutron" density. The more hydrocarbons in the formation, the more the neutrons will be slowed by interactions with the hydrogen proton. (a larger nucleus tends to reflect the neutron - smaller absorb more energy - think of a marble shot at a bowling ball versus another marble) Thus a large return of so called "thermal neutrons" meant a large amount of hydrocarbons in place. Or, a different form of this looked for the higher energy returns. (epithermal neutrons) Same principle.

I would think they would also want to use a gamma ray emitter as well, (Cesium 137) as rock density is easily calculated by the scattering of these. The density of coal is quite noticeable on a well log of rock density as it is much lower than sand stone or shale, the typical surrounding rock formations of a coal seam.