Thank you very much, that was fascinating.
Are you a mining-chemical engineer by trade?
My paternal grandfather was an architect at the Bingham Kennecott copper mine, which required a lot of chemistry as you well know.
I'd guess the Scott furnace might be what Langhorne permitted, since it didn't require the steel etc the rotary evidently did.
I suspect the empire's demand for detonators will keep increasing so the cost will continue to come down for at least the next couple of years, but peacetime construction especially infrastructure ought to still keep demand high for the next several years.
L
Captain Igloo wrote:*quote="alj_sf"*white phosphorous is proscribed, red one is labeled dangerous (or is it the reverse ?).
mercury metal or compounds can be labeled dangerous, but deliberate use of mercury fumes (which do not mean heating metal a lot) can only be proscribed as it is very toxic and prone to diffusion in the air.*quote*DrakBibliophile wrote:Technically, dangerous chemicals are not "proscribed" but are labeled "very dangerous & here's what happens if you use them".
Quicksilver/Mercury - production know-how:
Among its many uses, the industrial, medical, and military applications of mercury or quicksilver have accounted for 87 percent of US consumption since the birth of the industry. Mercury is unique as the only metal in liquid form at ordinary temperatures. It has seen use in the manufacture of chlorine and caustic soda, also in electrical components including lighting equipment and batteries, as well as precision measurement instruments such as thermometers and barometers. In more recent applications, mercury saw widespread use as a binding agent in the production of pulp and paper, as a mildew retardant for paints, and as an amalgam for dental preparations. It is mercury's well known explosive qualities, however, that has accounted for the uneven market fluctuations coincident with US involvement in global warfare. During such periods, the metal, once converted into a crystalline fulminate, becomes the principal chemical ingredient in the manufacture of detonators as well as other munitions. While there are few satisfactory substitutes for mercury in the production of electrical apparatus and control instruments, sulpha drugs, iodine and other antiseptics have replaced this unique metal in pharmaceutical use. Similarly, porcelain and plastics have become the preferred material employed in dentistry.
Of all the metals, quicksilver is probably the most easily recovered from its ore - cinnabar or mercuric sulfide. It can be easily reduced and, as it can be volatilized at a comparatively low temperature, thus separated without difficulty from nearly all substances that might be present in the ore. The principle upon which the extraction of mercury is based is a simple roasting operation that oxidizes the sulfide and produces mercury vapor. According to Curt N. Schuette, coauthor of "The Metallurgy of Quicksilver", acclaimed as the definitive essay onthe mining and processing of mercury, the melting point of cinnabar lies somewhere above 580 degrees centigrade, known as its subliming point. If sublimation alone is to be depended upon to extract the mercuric sulphide content of ore, temperatures
somewhat above that melting point is required. When cinnabar is roasted with very little or no air, as when the ore or concentrate is retorted, chemical changes other than those involving oxidation of the sulphide are depended upon to separate the mercury.
In the complete absence of oxygen, very little mercury will be released until reaching the subliming point of the cinnabar ore; therefore, in the retort process, it was standard practice to release mercury from its combination with sulphur by adding lime to the charge. The retort furnace was the earliest device used for the extraction of quicksilver from the ore. Generally, the retort furnace served two purposes: 1)it was used in the treatment of selected ore and 2) the recovery of quicksilver from the intermediate products of the reduction works, i.e. mercurial soot. Typically, a"D-type retort furnace" (so named after their D-shaped cross section) had a capacity from 750 to 1,000 pounds per 24-hour period.
The ubiquitous Huettner-Scott furnace (generally known as the Scott furnace) was the uncontested hallmark of the U.S. mercury mining industry for almost a half-century. First developed in 1875 at New Almaden, California by Robert Scott, a furnace mason, and mechanical engineer H. J. Huettner, the furnace revolutionized the reduction of mercury from its solid to liquid state, making the process both simple and economical. In the Scott furnace the open ore shaft is replaced by one or more pairs of narrow shafts containing shelves of fire-clay tile set at an angle of 45 degrees and placed alternately against the walls of the shafts to form a zigzag pattern. These form a series of inclined hearths down which the ore travels by gravity. The ore is heated by the hot gases emanating from the fire box below, which pass .through the flues formed by the inclined tiles. A single shaft usually contains about 26 tiers of tile, making the vertical dimension of the shaft itself about 30 feet. The length of the furnace is determined by the number of tile used in each tier, usually from two to five; and the width is determined by the number of shafts. Typically, a four-shaft, four-tile furnace processed 40 to 50 tons of ore in a 24-hour period. Toward the end of its usefulness to the industry, proponents of the Scott furnace heralded the fading technology as antiquated but nonetheless practical.
President Woodrow Wilson's decision to declare war on Germany in April 1917 and the subsequent commitment of American troops to France, prompted an unprecedented demand for quicksilver - especially mercury fulminate - on a global scale. Used as a primer to detonate gunpowder in cartridges and shells, mercury became a critical material in war - and its economic potential multiplied manyfold. The industry responded to the increased demand with the introduction of the Gould-type rotary furnace, which replaced the inefficient Scott furnace. Typically, furnace shells, averaging 50-60 feet in length and set at an incline of 1 foot for every 8 feet of pipe extending outward from a firebox, positioned at one end of the kiln over a small pit into which the roasted ore is discharged. Most furnaces rotated at one-third to two-thirds revolution a minute, processing about 30-50 tons of ore in a 24-hour period. On the whole, rotary kilns were far more productive as well as more efficient than the old Scott furnace. In the latter, for example, the ore is heated very gradually, freguently taking 24 hours or more to complete the process. With the rotary kiln reduction time never exceeded more than an hour. Because of the short roasting period, however, the grade of ore fed to the rotary furnace had to be fairly standard. A second obvious advantage of the rotary furnace was its mobility. Unlike the Scott furnace, the rotary could be easily disassembled and moved whenever necessary.
The condenser system functioned in a fashion that was standard to the industry. The heated gases from the furnace ordinarily were reduced in temperature by bringing them into contact with the cooler surfaces of the condenser, in which temperatures werelowered by either air cooling, water or both. The condensed liquid mercury then was collected in gutter-like drains that run along the lower side and bottom of the condensers from which it could be bottled into the standard 76 lb cast iron flasks for shipment. Oftentimes the resultant residue, or mercurial soot, also requires collection and reprocessing to extract all remaining traces of quicksilver. Although the two processes of cooling and collecting are considered separately, in actual operation they are largely simultaneous.
At its peak, mercury sold for $125 per flask in 1916 dropping to about $117 per flask the following year, $105 in 1918, and eventually to $90 per flask in 1944.
