So′da-fur′nace.
A furnace for converting sulphate of soda, obtained by treating common salt with sulphuric acid, into the carbonate.
This is effected by fusing the sulphate in combination with chalk and slaked lime or small coal,—according to
Leblanc, 100 parts sulphate, 100 chalk, and 50 slaked lime,—but the proportions are varied.
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Soda-furnace. |
A (
Fig. 5277) represents the rotary furnace used for the purpose.
It consists of an iron cylinder
a lined with fire-clay and having an opening at one side into which the charge is dumped from a wagon above, the cylinder having been previously heated red-hot.
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2236]
The opening is then closed, and the cylinder, which is provided with exterior ribs resting on friction-wheels beneath, is caused to make a few semi-rotations until the mass inside fuses, when a slow rotatory motion is maintained until the operation is completed.
The rotation is effected by suitable belting and gearing, and during the process the heat is maintained by the products of combustion from the furnace
b, which pass through the cylinder from end to end, and are carried off by the flue
c. The charge in
England is usually about 14 cwt. On the Continent, where the reverberatory furnace is in general use, much larger quantities are employed.
The crude soda is refined by lixiviation.
B represents Desorme's apparatus for this purpose.
It consists of a number of tanks
a b c d e (usually 12 or 14 are employed) connected by a series of bent pipes ascending from the bottom of each vat to the top of that next below it in the series.
The tanks are filled with warm water, and in
e are placed two perforated vessels filled with pulverized soda; at the expiration of 25 minutes these are removed to
d and replaced by others; the vessels are thus transferred consecutively from the lower to the higher vats until all are filled, when the first are removed, drained, and emptied.
Each time that fresh soda is placed in the vat
e an equal quantity of water is added to the upper vat, causing a transferrence of the same amount of lye from each vat to the one below it, until finally received in the clearing-tank
f, where any impurities are deposited.
