The Monteponi Company smelts its own zinc, but the lead is almost all smelted at the furnaces of Pertusola near Spezia.
Copper is smelted in Ardennes and Pas-de-Calais.
It makes excellent charcoal, especially for metallurgic processes; the Sussex iron, formerly regarded as the best produced in Britain, was smelted with oak charcoal from the great woods of the adjacent Weald, until they became so thinned that the precious fuel was no longer obtainable.
These ores were worked by the ancients, but so inefficiently that their spoilheaps can be smelted again with profit.
Lead ores are smelted in the reverberatory furnace, the ore-hearth, and the blast-furnace.
While by the English and Carinthian processes as much lead as possible is extracted in the furnace, with the Silesian method a very low temperature is used, thus taking out about one-half of the lead and leaving very rich slags (50% lead) to be smelted in the blast-furnace, the ultimate result being a very much higher yield than by either of the other processes.
Thus, a mixture of lead sulphate (45%) and oxide (44%) with some sulphide (8%), zinc and carbonaceous matter, is agglomerated by a heap-roast and then smelted in a slag-eye furnace with grey slag from the ore-hearth.
Ores are smelted raw if the fall of matte (metallic sulphide) does not exceed 5%; otherwise they are subjected to a preliminary oxidizing roast to expel the sulphur, unless they run too high in silver, say 100 oz.
To the ton, when they are smelted raw.
The Yzerberg near Marabastad in the Zoutpansberg consists of exceedingly rich iron ore, which has been smelted by the natives for many centuries.
The dressed ore is smelted with carbon by one of two main methods, viz.
Either in the shaft furnace or the reverberatory; the former is the better suited to stream tin, the latter to lode tin, but either ore can be smelted in either way, although reverberatory practice yields a purer metal.
The ore is smelted at Lubumbashi, where in 1918 were seven furnaces with a producing capacity of 40,000 tons a year.
In Colorado the pyritic ores containing gold and silver in association with copper are smelted in reverberatory furnaces for regulus, which, when desilverized by Ziervogel's method, leaves a residue containing 20 or 30 oz.
This is smelted with rich gold ores, notably those containing tellurium, for white metal or regulus; and by a following process of partial reduction analogous to that of selecting in copper smelting, " bottoms " of impure copper are obtained in which practically all the gold is concentrated.
Sulphuretted ores are smelted, either with or without a preliminary calcination, with metallic iron; calcined ores may be smelted with carbon (coal).
The ore of the metal occurring in the Mississippi basingalena----is scattered widely and in large quantities, and being easily smelted by the roughest possible methods was much used at an early date.
Magnetites were also early employed, at first in Catalan forges, in which by means of a direct process the metal was secured from the ores and forged into blooms without being cast; later they were smelted in blast furnaces.
The total refined domestic product in 1907 was 337,340, and the total domestic lead smelted was 365,166 tons.
Of the soft lead smelted in 1907 no less than 94.8% came from Missouri.
Iron is found in eastern Tibet in the form of pyrites, and is rudely smelted locally.
Iron is found in many districts and is smelted in a few places.
Iron is smelted by the natives, who, especially amongst the Hausas, are very clever smiths, and manufacture fine lances and arrow heads, knives and swords, and also hoes.
The process adopted for the Canadian ores, which are poor in copper and nickel, consists in a preliminary roasting in heaps and smelting in a blast furnace in order to obtain a matte, which is then further smelted with a siliceous flux for a rich matte.
This iron needed no tempering, and the Celts had probably found it ready smelted by nature, just as the Eskimo had learned of themselves to use telluric iron embedded in basalt.
Which would have advanced the most at the end of a month--the boy who had made his own jackknife from the ore which he had dug and smelted, reading as much as would be necessary for this--or the boy who had attended the lectures on metallurgy at the Institute in the meanwhile, and had received a Rodgers' penknife from his father?