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The Falls

Title: Description of the Smelting Process
Type: Book
Date: 1892
Source: Minnesota Historical Society

Description: This page from the Miner's Guide describes the processes that are used to extract metals from ores.

Transcription:

6.—IRON

Geognostic Situation—It occurs in primary and secondary rocks.

Extraction—The ore is first broken into small pieces by the aid of the stamping-mill. (See Gold.) After this it is roasted with a strong heat. It is then transferred to the blast-furnace, An oven used to heat and refine iron ore. in which the operation of smelting Melting the ore to separate the metal from the rock. is conducted. This is a large pyramidal stack, made of brick or hewn Cut with blows from a heavy cutting tool. stone, form twenty to sixty feet high, having the inside cavity The opening inside the blast-furnace in which the ore is placed and the fire is started. shaped like an egg, with its large end downwards and lined with fire-brick or stone. Into this is placed alternate layers of charcoal or coke, and of the metallic matter; a quantity of lime A powder used to heat the fire in the smelting process. is at the same time added as a flux. A substance used to encourage the separation of the metal from the ore in the blast-furnace. Before putting these in, however, the furnace must be first heated with coal only for twenty-four hours, and is then charged with the ore, etc., until it is quite full; a strong heat is then excited by bellows. This is a machine designed to pump air into the fire and make the fire burn more fiercely. As fast as the materials sink, by the melted metal being drawn out, the charge is renewed at the upper part. The opening, while metal collects at the bottom. The latter is conveyed off at intervals, and cast into moulds, and is then known as pig iron or crude iron. To obtain it still purer, it is broken in pieces and kept in fusion in a puddling-furnace, where it is raised to a very high temperature, and frequently stirred with an iron rod. At length the mass swells, emits a blue flame, and gradually becomes stiff an dpasty. It is finally raised in a rude ball, and placed under the blows of a large tilt-hammer. It is cut up, and piled or fagoted, and reheated several times, until it is made into tough and fibrous metal. It thus becomes the malleable iron of commerce, under the name of wrought, forged, or bar iron.