There are many resources and publications available over the internet for those more interested in the science behind bulk solids and powder technology. Some of these resources include:
http://www.powderbulksolids.com
http://www.jenike.com
http://www.kona.or.jp/index_e.html
http://www.chemicalprocessing.com/resource_centers/powder_solids.html
http://www.asce.org/PPLContent.aspx?id=17273
http://www.bulk-solids-handling.com/
http://www.aiche.org/publications/aichejournal/index.aspx
http://en.wikipedia.org/wiki/Geotechnical_engineering
http://www.erpt.org/retiredsite/default.htm