The pan amalgamation process is a method to extract silver from ore, using salt and copper(II) sulfate in addition to mercury. The process was widely used from 1609 through the 19th century; it is no longer used.
The patio process had been used to extract silver from ore since its invention in 1557. One drawback of the patio process was the long treatment time, usually weeks. Alvaro Alonso Barba invented the faster pan process (in Spanish the cazo or fondo process) in 1609 in Potosí, Bolivia, in which ore was mixed with salt and mercury (and sometimes copper(II) sulfate) and heated in shallow copper vessels. The treatment time was reduced to 10 to 20 hours. Whether patio or pan amalgamation was used at a particular location often depended on climate (warmer conditions speeded the patio process) and the availability and cost of fuel to heat the pans. [1]
The amount of salt and copper(II) sulfate varied from one-quarter to ten pounds of one or the other, or both, per ton of ore treated. The loss of mercury in amalgamation processes was generally one to two times the weight of silver recovered.
The Washoe process, a variation of pan amalgamation, was developed in the 1860s by Almarin B. Paul and others, to work the ore from the Comstock Lode in Nevada, United States (Washoe was an early name for the area and the local tribe who still exists today; see Washoe Valley). [2] : 41 In the Washoe process, the copper pans were replaced by iron tanks with mechanical agitators. Each tank ("pan") was circular, and commonly held 1,200 to 1,500 pounds of ore that had been crushed to sand size. Water was added to make a pulp, and 60 to 70 pounds of mercury, along with one-half to three pounds each of salt (sodium chloride) and bluestone (copper(II) sulfate) were also added. A circular iron plate called a muller was mounted on a vertical shaft and lowered into the pan, and was rotated to provide both agitation and additional grinding. Heat was delivered to the pans by steam pipes. The iron filings worn from the muller and pan proved to be an essential ingredient in the process. [3] [4]
A variation of the Washoe process was developed in the Reese River mining district around Austin, Nevada. The Washoe process was found not to work well for ores with arsenic or antimony sulfides, or with galena or sphalerite. In 1869, Carl A. Stetefeldt of Reno found that roasting the ore with salt converted the silver sulfides to silver chlorides, which could then be recovered in amalgamation pans. [5] The process was introduced in the Reese River District in 1879, with great success.
Other silver-mining districts using the Reese River process included Georgetown, Colorado, Caribou, Colorado, and Silver Cliff, Colorado. [6]
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The Carson River is a northwestern Nevada river that empties into the Carson Sink, an endorheic basin. The main stem of the river is 131 miles (211 km) long although the addition of the East Fork makes the total length 205 miles (330 km), traversing five counties: Alpine County in California and Douglas, Storey, Lyon, and Churchill Counties in Nevada, as well as the Consolidated Municipality of Carson City, Nevada. The river is named for Kit Carson, who guided John C. Frémont's expedition westward up the Carson Valley and across Carson Pass in winter, 1844. The river made the National Priorities List (NPL) on October 30, 1990 as the Carson River Mercury Superfund site (CRMS) due to investigations that showed trace amounts of mercury in the wildlife and watershed sediments.
The Comstock Lode is a lode of silver ore located under the eastern slope of Mount Davidson, a peak in the Virginia Range in Virginia City, Nevada, which was the first major discovery of silver ore in the United States and named after American miner Henry Comstock.
Copper extraction refers to the methods used to obtain copper from its ores. The conversion of copper ores consists of a series of physical, chemical and electrochemical processes. Methods have evolved and vary with country depending on the ore source, local environmental regulations, and other factors.
Austin is an unincorporated small town in, and former county seat of, Lander County, Nevada, United States. In 2020, the census-designated place of Austin had a population of 167. It is located on the western slopes of the Toiyabe Range at an elevation of 6,575 feet (2,004 m). U.S. Route 50 passes through the town.
The patio process is a process for extracting silver from ore. Smelting, or refining, is most often necessary because silver does not very frequently occur in the nature by itself as a native element mineral like some metals nobler than the redox couple 2 H+ + 2 e−⇌ H
2 (gold, mercury, ...). Instead, it is made up of a larger ore body. Thus, smelting, or refining, is necessary to reduce the Ag+ cation into metallic Ag and to remove other byproducts to get at pure silver. The process, which uses mercury amalgamation to recover silver from ore, was reportedly invented by Bartolomé de Medina in Pachuca, Mexico, in 1554. It replaced smelting as the primary method of extracting silver from ore at Spanish colonies in the Americas. Although some knowledge of amalgamation techniques were likely known since the classical era, it was in the New World that it was first used on a large industrial scale. Other amalgamation processes were later developed, importantly the pan amalgamation process, and its variant, the Washoe process. The silver separation process generally differed from gold parting and gold extraction, although amalgamation with mercury is also sometimes used to extract gold. While gold was often found in the Americas as a native metal or alloy, silver was often found as a compound such as silver chloride and silver sulfide, and therefore required mercury amalgamation for refinement.
Various theories of ore genesis explain how the various types of mineral deposits form within Earth's crust. Ore-genesis theories vary depending on the mineral or commodity examined.
Silver mining is the extraction of silver from minerals, starting with mining. Because silver is often found in intimate combination with other metals, its extraction requires elaborate technologies. In 2008, ca.25,900 metric tons were consumed worldwide, most of which came from mining.
Alison "Eilley" Oram Bowers was a Scottish American woman who was, in her time, one of the richest women in the United States, and owner of the Bowers Mansion, one of the largest houses in the western United States. A farmer's daughter, Bowers married as a teenager, and her husband converted to Mormonism before the couple immigrated to the United States. After briefly living in Nauvoo, Illinois, she became an early Nevada pioneer, farmer and miner, and was made a millionaire by the Comstock Lode mining boom. Married and divorced two times, she married a third time and became a mother of three children but outlived them all.
Silver mining in Nevada, a state of the United States, began in 1858 with the discovery of the Comstock Lode, the first major silver-mining district in the United States. Nevada calls itself the "Silver State." Nevada is the nation's second-largest producer of silver, after Alaska. In 2014 Nevada produced 10.93 million troy ounces of silver, of which 6.74 million ounces were as a byproduct of the mining of gold. The largest byproducers were the Hycroft Mine, the Phoenix Mine, the Midas Mine and Round Mountain.
The History of Nevada as a state began when it became the 36th state on October 31, 1864, after telegraphing the Constitution of Nevada to the Congress days before the November 8 presidential election. Statehood was rushed to help ensure three electoral votes for Abraham Lincoln's reelection and add to the Republican congressional majorities.
Gold mining in Nevada, a state of the United States, is a major industry, and one of the largest sources of gold in the world. In 2018 Nevada produced 5,581,160 troy ounces, representing 78% of US gold and 5.0% of the world's production. Total gold production recorded from Nevada from 1835 to 2017 totals 205,931,000 troy ounces (6,405.2 t), worth US$322.6 billion at 2020 values. Much of Nevada's gold production comes from large open pit mining using heap leaching recovery.
An amalgam is an alloy of mercury with another metal. It may be a liquid, a soft paste or a solid, depending upon the proportion of mercury. These alloys are formed through metallic bonding, with the electrostatic attractive force of the conduction electrons working to bind all the positively charged metal ions together into a crystal lattice structure. Almost all metals can form amalgams with mercury, the notable exceptions being iron, platinum, tungsten, and tantalum. Silver-mercury amalgams are important in dentistry, and gold-mercury amalgam is used in the extraction of gold from ore. Dentistry has used alloys of mercury with metals such as silver, copper, indium, tin and zinc.
Poeville, also known as Peavine until 1863, is the site of a historical mining town, established in 1864. John Poe, a professional promoter from Michigan allegedly related to Edgar Allan Poe, discovered rich gold and silver veins in 1862 on the slopes of Peavine Mountain. After the discovery of ore, Poe announced that the veins comprised the next Comstock Lode; he presented extracted ore at the state fair of 1864 as rich in content. As a result, the former mining camp, called Poe City (Poeville) or Podunk (Poedunk), grew to 200 people by 1864. Ore production in the mining district and population peaked around 1873-1874 with several hundred people living in town, supported by three hotels and a post office. The post office, named "Poeville", operated between September 1, 1874, and March 24, 1878.
Leviathan Mine is a United States superfund site at an abandoned open-pit sulfur mine located in Alpine County, California. The mine is located on the eastern slope of the Sierra Nevada at about 7,000-foot (2,100 m) elevation, 6 miles (9.7 km) east of Markleeville and 24 miles (39 km) southeast of Lake Tahoe. The mine site comprises approximately 250 acres (100 ha) of land surrounded by the Toiyabe National Forest, which is only accessible a few months a year. The approximately 22 million tons of sulfur ore-containing crushed rock at the mine are responsible for contaminating the Leviathan and Aspen Creek, which join with Mountaineer Creek to form Bryant Creek which ultimately empties into the East Fork of the Carson River. These water bodies are listed as 303(d) impaired. The site location is seismically active.
Eagle Valley is the area encompassing Carson City, Nevada. The valley was first settled during the California Gold Rush of 1849. The discovery of Nevada's Comstock Lode in 1859 established the economic importance of the area, which would become the site of the Nevada State Capitol.
Carl August Stetefeldt was a United States mining engineer.
Bartolomé de Medina was a Spanish merchant known for his invention of the patio process.
Rhodes, Nevada is a former rail station and Post Office on the Carson and Colorado Railway in Mineral County, Nevada.
Steamboat Creek drains Washoe Lake, flowing north to northeast through Truckee Meadows and finally intersecting the Truckee River, east of Reno, Nevada. Historical documents indicate that in the early 1860s there were at least six mills reducing Comstock ore in Washoe Valley and during these earliest days of the Comstock mining.