Construction and operation of a blast furnace for iron smelting from ironsand in Dabieshan according to Guo Yujing, 1932

The original gives dimensions in English units and weights in Chinese units; in the translation these are converted to metric. The text has no illustrations, but the diagram below, from 1958, fits the description very well.

Højovn, 1958
Section through a blast furnace in Macheng amt, Hubei, 1958. Dimensions are given in ‘market inches’ (shicun, 3.3 cm). (Redrawn from Yejin bao, 1958, no. 45, p. 22).

The blast furnace, or ‘sand-smelting furnace’, has the following dimensions:

     • height 183–244 cm
     • upper diameter 66–104 cm
     • middle diameter 36–86 cm
     • lower diameter 41–94 cm

It is divided into an upper and a lower section. The outside is hooped with iron bands, four each on the upper and lower sections. These are joined together by several straight iron rods.  . . .

The area around the taphole is the most subject to melting. In Xinyang, sandstone from Jiayu County, Hubei, is used [for the taphole stones]; in Shangcheng, diatomaceous earth from Qishui [modern Xishui], Hubei, is used. The two materials are equally refractory.

Materials for furnace construction

Loess and sand are used, together with unburnt charcoal from furnace slag, washed and powdered. This is called ‘charcoal powder’. The loess is mixed with sand and charcoal powder and plastered evenly on the inside of the furnace. The proportion of loess to white sand is ca. 100 to 34. When this has dried, charcoal powder is plastered over the whole; then the furnace is ready. At the bottom, where the temperature is highest, old taphole stones (diatomaceous earth) and a small amount of salt are added to the charcoal, loess, and sand.


The material is the same as above. This is formed into a long tube, 61 cm long, with outer diameter 10 cm, inner diameter 5 cm, weight ca. 20 kg. One furnace uses four tuyères every 24 hours. The most important detail in the installation of the tuyère is its angle: the blast should be directed precisely toward the taphole. Otherwise the temperature will be insufficient.

The windbox

A wooden windbox is used for the blast. It is 213 cm long, with inner diameter 30 cm, outer diameter 41 cm. Valves are installed inside. The shaft is 366 cm long. It is worked by two persons.


First the furnace is filled with charcoal. This is burned until the furnace bottom is extremely hot. Then another layer of whole charcoal is added, followed by a layer of crushed charcoal, to a thickness of 61 cm. Then a small amount of ironsand is added, thickness ca. 2.5 cm.

The blast is operated until the top of the furnace burden sinks down; then charcoal and crushed charcoal, thickness 13 cm, and ironsand, thickness 2.5 cm, are added continuously in a cycle. After the third addition of ironsand, molten iron appears. Charcoal and ironsand are added one more time, and then the molten iron is tipped out. At the same time a hooked measuring rod is inserted into the tuyère. If the tuyère has been shortened by melting it is pushed further in, so that it is flush with the inner wall. In one day and night the inputs are:

  • charcoal 4200 kg
  • ironsand 3000 kg

And the output is

  • pig iron 1300 kg

The molten iron is tipped into a large iron ladle which is lined with a mixture of salt and loess and further with charcoal powder. The iron is poured into a sand form, 51 cm long and 13 cm wide.

The furnace lining . . .  is subject to corrosion. It should be repaired every two or three days.

The smelting slag does not flow freely; it contains small pieces of charcoal and bean-shaped iron aggregates. These are crushed, washed, and returned to the furnace.

Translated from Zhang Youxian og Guo Yujing, ‘Henan tiekuang’, Henan sheng dizhi diaochasuo huikan, 1932, 1: 239–241. This and several other descriptions, from 1916 and 1958, are translated in my Dabieshan, London & Malmö 1985.

Click on the image to see it enlarged.