Raw ore blowing - Namakoubuki

Japanese: 生鉱吹 - なまこうぶき

This was one of the smelting methods from the time when copper was smelted in a blast furnace. The ore used for copper smelting often contains chalcopyrite and pyrite. Currently, pyrite and gangue are separated by flotation to produce a concentrate before smelting, but this technology did not exist until the beginning of the 20th century, and so copper was low-grade and ore with high iron and sulfur content had to be smelted. For this reason, there were two methods: the reduction smelting method, in which the ore was roasted before being put into the blast furnace, and the furnace temperature was maintained by burning a lot of coke or coal, and reduction was carried out inside the furnace; and the smelting method, in which the ore was not roasted but iron and sulfur were oxidized in the blast furnace and used as a heat source to smelt the metal using as little fuel as possible.

Source: Heibonsha World Encyclopedia, 2nd Edition Information

Japanese:

銅が溶鉱炉によって製錬されていた時代の溶錬法の一つ。銅製錬に用いる鉱石には黄銅鉱や黄鉄鉱が含まれている場合が多く，現在では浮遊選鉱によって黄鉄鉱や脈石を分離して精鉱としてから製錬を行うが，20世紀初めころまではこの技術がなく，したがって銅の品位は低く，鉄，硫黄分の高い鉱石を製錬しなければならなかった。そのため，溶鉱炉に入れる前に鉱石をあらかじめ焙焼（ばいしよう）し，溶鉱炉では，コークスや石炭を多く用いて，この燃料の燃焼により炉温を維持し，炉内で還元を行わせた還元吹と，鉱石を焙焼することなく，溶鉱炉で鉄と硫黄を酸化してこれを熱源とし，なるべく燃料を使わないで溶錬する方法とがあった。

出典　株式会社平凡社世界大百科事典第２版について　情報

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