A final report is not complete because debris still needs to be removed from the elevator, and fire is smoldering in the bin areas.
At the time of the explosion, the bins were about two-thirds full of mostly corn. Workers were loading grain onto a train in that area when the explosion occurred, according to the fire marshal.
The Occupational Safety and Health Administration (OSHA) is conducting a separate investigation into the explosion, which may not be finished for several months, the newspaper reported.
Bartlett officials have said the company plans to rebuild the facility, but has not given a timeframe for the construction.
The blast killed four Bartlett employees, John Burke, 24, of Denton, and Ryan Federinko, 21, Curtis Field, 21, and Chad Roberts, 20, all of Atchison, and two private grain inspectors, Travis Keil, 34, of Topeka, and Darrek Klahr, 43, of Wetmore.
Pat Maxwell remains in critical condition at the University of Kansas Hospital. Clinton Ellerman, who was seriously injured in the explosion, has been released from the hospital, the newspaper reported.