On the Measurements Concerning a Rotary Kiln in Operation

Study on the pre-reduction of iron sand with a rotary kiln-I

Abstract

Nowadays interest is still being aroused in methods for direct reduction bypassing the blast furnace. In the previous literatures we can find some practical operating data on the direct reduction that makes use of a rotary kiln as reducing device, but scarcely any kinetic or analytical research on the process.
We have produced pig iron in a submerged type electric smelting furnace through halfreduced sponge iron which is obtained from iron sand in a rotary kiln since early 1956. Recently we constructed a 46m long kiln for various tests, equipped with 6 sampling holes for different purposes. By this equipment we tried to make an overall measurement of the reducing kiln.
The measurement of the rotary kiln was made on the following items:
(1) Temperature of raw material at 7 points along the axis of kiln.
(2) Spot sampling of material at the same points and its chemical analysis.
(3) Spot sampling of atmospheric gas at the same points and its chemical analysis.
(4) Temperature of iron shell and others.
We obtained some results after several measurements and analysis on the operating kiln, especially suggested the importance of abnormal phenomenon i. e., segregation of raw material in the rotary kiln, which has influence on the reducing reaction and others.
In this paper we show the dimensions of the test kiln, equipments and methods for measuring, and then present the results of measurements.