Rotary Kiln Hopper and Chimney

The side of the rotary kiln accepting ore crushed to fit through a 2″ screen serves the following functions.

  1. It supports the end of the kiln.
  2. It provides an exhaust for the chimney.
  3. It includes a hopper that allows incoming ore to be loaded into the kiln.

This only photo of the prototype of the hopper and chimney area is not very revealing.

Rotary Kiln Stack1

This is from a 1917 rotary kiln drawing and shows a hopper and support mechanism from the side.



This shot of an early English rotary kiln shows a masonry firebox support with the chimney coming out the top.

Kiln Chimney

A close look at the first photo reveals the fire box feeding the chimney to be also made from masonry.  The end would have been deeper on the Sonoma kiln to allow the hopper to be placed near the top front and the chimney to come out the top rear.   Note that the chimney diameter in this photo appears to be around two feet, but the chimney on the Sonoma kiln is of a smaller diameter, slightly smaller than the hopper tube.

Time to make some executive decisions.

  • The fire box supporting the hopper and chimney will be modeled based on the English kiln in the above photo, except it will be wider to support both the chimney and the hopper.
  • It will be all brick up to the point the chimney and hopper exit the fire box.  Construction will use .060 styrene sheet with Plastruct rough brick applied to the surface.
  • 1:1 dimensions will be 14′ high by 10′ wide by 8′ deep.  That scales to 3 1/2″ x 2 1/2″ x 2″.
  • Both the chimney and the cylindrical portion of the hopper will be 2′ in 1:1 scale or 1/2″ scaled.
  • The kiln will be supported with a PVC ring similar in size to the tires.
  • The fire box will have a fire door similar to that in the above photo except the top will be squared rather than rounded.
  • The rectangular portion of the hopper will be built to accept material from the conveyor on order which scales to 4 1/2″ high.



This is a shot of the styrene piece that will be the wall of the fire box that receives the kiln cylinder.  I used the PVC joiner to scribe a circle that would allow the cylinder to pass through the wall.  Then I drilled 1/8″ holes inside the circumference (mostly) and used an Exacto knife to connect the holes.


The next step is to glue a PVC joiner to the back of this sheet, then use a rat tail file to size and smooth the final opening.  While the epoxy was setting up I moved on to the fire box roof.  Two openings were required, one for the smoke stack and the second for the cylindrical portion of the hopper.  I drilled 1/4″ holes in the roof, used the stack to draw two circles, then used a rat tail file to file the opening so it would accept 1/2″ tube.  As you can see I used a couple of pieces of Plastruct square tube to convince the chimney not to lean.


This shot shows progress in the fire box, hopper and chimney area.  In addition to the top of the firebox supporting the chimney and tube portion of the hopper, the firebox wall facing the tube is also shown.  As you can see it is designed to support the cylinder at a downward slant from where it enters the fire box.  You can also see the three other sides and the bottom of the fire box.  The firebox will be surfaced with Plastruck brick which is on order.  The brick will come most of the way up the fire box.  The last portion will be modeled as a steel hood.


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