Smelting early

The focus of this section is the emission of ultraviolet and visible radiation following thermal or electrical excitation of atoms. Atomic emission spectroscopy has a long history. Qualitative applications based on the color of flames were used in the smelting of ores as early as 1550 and were more fully developed around 1830 with the observation of atomic spectra generated by flame emission and spark emission.Quantitative applications based on the atomic emission from electrical sparks were developed by Norman Lockyer (1836-1920) in the early 1870s, and quantitative applications based on flame emission were pioneered by IT. G. Lunde-gardh in 1930. Atomic emission based on emission from a plasma was introduced in 1964. 

As of this writing (ca 1994) none of the newer lead smelting technologies has been adopted in the United States. Also, no new lead mine has opened in the United States since the early 1980s. Most of the known U.S. reserves for lead are located in federally owned land in Missouri future mine development depends on the outcome of the U.S. government s intent to reform the Mining Law of 1872. 

The smelting process seems to have been independently discovered in the Middle East, China, and Southeast Asia. The chronological sequence in which the different metals were brought into use was probably determined by the difficulty in winning them from their ores. Copper, for example, which melts at just above 1000°C, a temperature within reach in a vented wood or charcoal fire, was separated from its ores quite early. Iron, which melts at above 1500°C, a temperature that for a long period of human technological development was out of reach, was first produced at a much later time. 

The sporadic use of iron can be traced back as far back as nearly 6000 years ago, but its widespread application came at a much later date, later than that of copper. This is probably due to a number of factors, mainly the high melting point of the metal (1535°C) and, accordingly, the high temperatures required for smelting it. Temperatures above 1200-1300°C were hardly accessible in early antiquity. A rudimentary form of iron known as... 

It seems that making arsenical copper was characteristic of a transitional stage of technological development, the alloy apparently first replacing pure copper and then eventually being supplanted by bronze. It is possible that during the early Bronze Age it was realized that the use of arsenic-rich copper ores, or the incorporation of arsenic ores into copper ores smelting... 

The Earth s crust, mantle and core are strongly influenced by differentiation processes which could have resulted from gravitational separation ( smelting ) in an early molten phase of the planet, or from the sequence in which different chemical species condensed from the primitive solar nebula and were subsequently accreted. Seismology indicates that there is a liquid core (with a solid inner core) with radius 3500 km consisting mainly of iron (with some Ni and FeS) surrounded by a plastic (Fe, Mg silicate) mantle of thickness 2900 km. 

Flintshire An early lead-smelting process in which galena was roasted in a reverberatory furnace. 

HIsmelt A direct iron smelting process in which noncoking coal, fine iron ore, and fluxes and gases, are injected into a molten iron bath the carbon monoxide produced is used to prereduce the ore in a fluidized bed. Under development by CRA, Australia, since the early 1980s, joined by Midrex Corporation in 1988. Their joint venture company, Hismelt Corporation, commissioned a pilot plant at Kwinana, near Perth, Australia, in 1993. 

Pollard, A.M., Thomas, R.G. and Williams, P.A. (1990). Experimental smelting of arsenical copper ores implications for Early Bronze Age copper production. In Early Mining in the British Isles, ed. Crew S. and Crew P., Occasional Paper No. 1, Plas Tan y Bwlch, Snowdonia National Park Study Centre, Gwynedd, pp. 72-74. 

As noted earlier, no viable theories of the smelt-water explosion had been widely accepted during the early period of investigation. Nelson in... 

Whereas these early experiments provided interesting data, no mechanism was developed to explain the explosion phenomenon. In fact, since the 1950s there has been little interest in conducting further studies in dissolver tanks because the addition of efficient steam-shatter jets at the smelt entrance has effectively eliminated explosions in this section of the process. Further studies were directed to the explosions which took place within the recovery boiler as a result of water contacting the smelt on the furnace floor. 

In about 3600 bce, ores containing both arsenic and copper were known and mined by the early Greeks and Romans, as well as by Chinese alchemists. This is about the time when copper was smelted and alloyed to make bronze. Some ores of copper produced harder metals than others because of impurities. One of these impurities was arsenic. Because the workers were becoming ill when smelting these types of ore, the process was abandoned, and tin was added to copper to form bronze. Bronze may have been the Persian (Iranian) word for copper. ... 

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