English: Reverberatory furnace used for the smelting of lead ores.

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LEAD SMELTING AT FREIBERG.

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Lead slags, poor dry ores, etc., are smelted in reverberatory furnaces, as represented in Fig. 32.

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The charges for this process are obtained by mixing twenty hundredweight of lead slags with five hundredweight of raw ore, five hundredweight of roasted ore, and two hundredweight of quartz. The charge is introduced by means of a movable hopper D and uniformly spread over the bottom B, making the layer somewhat higher near the firebridge E.

The smelting is conducted with the exclusion of atmospheric air for about three hours, when the almost fluid mass is stirred and exposed for twenty minutes to a still higher temperature, after which the slag is drawn ofT. After two or three charges have been smelted in this way, a considerable amount of lead regulus, or matte, will have been reduced, which is tapped off and cast into molds and allowed to cool. It is next broken into pieces of the size of a fist, roasted, and mixed with a charge of lead ores to be smelted in a blast furnace, as represented in Fig. 44.