Читать книгу Lead Smelting and Refining, With Some Notes on Lead Mining онлайн

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Fume-Lead from Hearth Silver-Lead from Hearth Slag-Lead from Blast Furnace Lead 99.957 99.957 99.013 Silver 0.0035 0.0200 0.0142 (1 oz. 2 dwt. 21 gr. per Long Ton) (6 oz. 10 dwt. 16 gr. per Long Ton) (4 oz. 12 dwt. 18 gr. per Long Ton) Tin nil nil nil Antimony nil nil 0.874 Copper nil nil 0.024 Iron 0.019 0.019 0.023 Zinc nil nil nil 99.9795 99.9960 99.9482

The ordinary form of the Scotch hearth is probably too well known to need much description. The dimensions which have been found most suitable are as follows: Front to back, 21 in.; width, 27 in.; depth of hearth, 8 to 12 in. Formerly the distance from front to back was 24 in., but this was found too much for the blast and for the men.

The cast-iron hearth which holds the molten lead is set in brickwork; if 8 in. deep and capable of holding about ¾ ton of lead, it is quite large enough. The workstone or inclined plate in front of the hearth is cast in one piece with it, and has a raised holder on either side at the lower edge, and a gutter to convey the overflowing lead to the melting-pot. The latter is best made with a partition and an opening at the bottom through which clean lead can run, so that it can be ladled into molds without the necessity for skimming the dross off the surface. It is well also to have a small fireplace below the melting-pot.