Smelted metals

FIGURE 33 Smelting flowchart. The chart shows, in diagrammatic form, the sequence of metallurgical processes required for extracting metals from their ores from the initial mining of metalliferous ores to the final refining of the smelt metals. 

Sometime after the discovery of processes for smelting metals, it became clear that some of their properties could be altered and in many cases improved by alloying, that is, by mixing metals with other elements. Some alloys made by mixing two metals, for example, were found to be harder or softer than the separate metals. Also the melting point of an alloy was often lower than that of its components, which made the alloys easier to work. Soon it was appreciated that many other properties of alloys, such as their strength, workability, and resistance to decay, were more suitable for required needs than were its components, and the manufacture and use of alloys become widespread (see Table 35). 

The method adopted for removing the antimony, tin, copper, sine, and other foreign matters, is often tedious and expensive. It Is founded upon the oxidation of those metals, and the separation of the dross of mixed oxides from the lead. To effect this, the smelted metal is to-melted in a levciberatery furnace, through which a Copious draught is Instituted, and allowed to remain In this state, the scum of oxide being removed from time to time till the most part of the easily oxidised impurities are separated. 

Several studies indicate that different methods cause adverse effects to embryonic and fetal tissues and eventually lead to the development of teratogenic effects. Metals are omnipresent in the living environment. A variety of anthropogenic activities (e.g., smelting metallic ore, industrial and metal fabrication, commercial application, burning of fossil fuels) have caused adverse effects to the developing fetus. In fact, notorious elements, such as cadmium, lead, and mercury, have been associated with injury and malformation to the growing embryo and fetus of animals and humans.65... 

Alkahest is another term from Paracelsus and is used to denote not only a solvent which can extract the Sulfur and Mercury of living metals, but also one that can specifically extract the Sulfur from dead or smelted metals, and infuse them with its own vitality to reanimate them. Alkahest was thought of as a Universal Solvent. Each of the Alkahests... 

Anodes for electrorefining must first be cast from the smelted metal, with a uniform thickness across each anode as well as from one anode to the next. Anodes which are too thick give too much scrap anode material for recasting when the spent anodes are changed. Anodes which are too thin or irregular in thickness can cause pieces of metal to drop off in the electrolytic cells resulting in electrical shorts and decreased current efficiencies. 

Soil contamination from smelting, metal plating, manufacturing, municipal and industrial wastes, and automobile traffic can increase soil concentrations of these ions to possibly toxic levels. Even so, animal problems generally occur only when contaminated plants are the sole food supply. Grazing animals confined to contaminated areas show the most serious effects of toxic metal accumulations in soils. 

Industrial-grade and chemical-grade potassium chloride are used mainly for the electrolytic production of potassium hydroxide. Other important uses include the production of drilling fluids for the oil industry, aluminum smelting, metal plating, production of various potassium compounds, and appli-... 

Arsenic oxide is commonly obtained as a byproduct of copper, lead and nickel smelting. Metallic arsenic is produced by carbon reduction of AS2O3. High-purity arsenic... 

A substance used in smelting metals to react with silicates and other impurities and form a low-melting slag. 

Despite these warnings of Craddock, which also apply to other mined and smelted metals like silver and iron, there have been serious attempts to glean locational information from analytical data. Berthoud, in his thesis research and in a paper published with several collaborators using plasma emission and spark source mass spectroscopy, analyzed the multivariate compositional data of copper ores from more than 25 copper mines in Iran, that would have been important in early (4th and 3rd millennium) metallurgy. Their feeling was that the Craddock Assumption 1) was satisfied well enough and furthermore that it was possible to trace certain 4th millennium objects from Susa to a native copper source at Talmessi. Of course, with native copper, Craddock Assumptions 2) and 3) were not tested. 

With the advent of civilization, chemical technology matured. Techniques requiring permanent structures (such as furnaces for smelting metals) could now be developed, and chemical processes could be recorded, repeated, and refined. We can piece together a picture of the methods used from artifacts that remain. The most durable of these are the metals, and metallurgy is the first chemical technology whose history we are able to reconstruct with some surety. 

B.c.E. Widespread use of fire by humans Fire is used for heat, light, food preparation, and driving off nocturnal predators. It is later used to fire pottery and smelt metals. 

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