Eureka Smelting History
Site Background — The Town of Eureka is considered the birthplace of silver-lead smelting in America. Eureka's boom years lasted from 1870-1885. A map of the Town of Eureka dated 1878 clearly shows the locations of 7 smelter sites and two mill sites within what is now the downtown area (see Figures 1 & 2). As early as 1869, lead smelters were in operation in Eureka. By 1873, 17 furnaces located in eight smelters were operating, with the Richmond Company and Eureka Consolidated smelters being the two largest and accounting for most of the production. In 1890 and 1891, the Richmond and Eureka smelters closed due to falling silver prices. In 1906, the Richmond and Eureka smelters merged to form the Richmond Eureka Consolidated; although a disastrous flood in 1910 ceased smelting operations.
View Historical Photos [11 Pages - 745KB]
- Eureka Consolidated Mill, Eureka, Nevada
- City of Eureka, Nevada taken from Richmond Smelter
- City of Eureka from Richmond Smelter looking North
- Town of Eureka
- Town of Eureka looking North from Richmond Smelter
- Town of Eureka
- Smelter in Town of Eureka
- Eureka Consolidated Smelter in Town of Eureka
Brief Description of the Smelting Process Used in the Town of Eureka — The smelting process utilized in the Town of Eureka primarily from 1869 through 1890 began with the mining of raw lead-silver ore from the mines located on Ruby Hill (located just a few miles southwest of the Town of Eureka). This ore was then hauled to mills and smelters located directly within the Town of Eureka (and at the north and south ends of town) for further processing.
The ores were crushed and then the finer ore material was loaded into a high temperature blast furnace which utilized charcoal as a heat source and melted to a molten liquid state. The molten material then flowed to the bottom of the blast furnace where four layers would form based on the density of the material: "Speiss" (the lightest material which is basically made up of arsenic and antimony) would rise to the top. "Matte" (the next lightest material which consisted of metal sulfides formed the layer below that. "Slag" (primarily silicates, similar to glass) and the silver lead bullion formed the lower two layers.
The silver lead bullion was then drained off and poured into bars for shipment to undergo further refining and separation into pure bars of silver and lead. The Speiss, Matte and Slag were sometimes recycled through the process for additional metal recovery (some was shipped off-site at a later date for additional metals recovery), but were typically disposed of on the surface of the ground at the smelter sites as waste material and are then referred to simply by the collective term "Slag."
History of Smelting in the Town of Eureka — The historical information presented below comes primarily from two sources. US Bureau of Mines Information Circular 7022, Reconnaissance of Mining Districts in Eureka County, Nevada by William O. Vanderburg - June 19381 and The Engineering and Mining Journal #23 - The Silver-lead Mines of Eureka, Nevada by Walter Renton Ingalls - December 7, 19072.
The Town of Eureka is generally conceded to be the birthplace of the silver-lead smelting industry in the United States and from 1869 to 1879 it was the source of a large part of the domestic production of pig lead. In the latter years, its importance as a lead producer was overshadowed by the deposits at Leadville, Colorado. The principal reason for the rapid expansion of the smelting industry at Eureka is attributed to the character of the ores; the ores contain the slag-forming constituents iron, lime and silica to make them largely self-fluxing1.
From 1869 through 1883 mines and smelters in the Eureka district reportedly produced 60 million dollars worth of gold and silver and another 24 million dollars worth (225,000 tons2) of lead for a total value of mineral production of over 84 million dollars1.
The furnaces used in the district were of the blast type designed after the Piltz and Raschette furnaces used in Europe. The first furnaces had daily capacities of from 20 to 50 tons per day, but later the capacity of individual furnaces was increased to 90 tons. The height of the furnaces was from 10 to 20 feet from the tuyeres (air intake) to the charging door1.
At the end of 1870 there were 14 furnaces, all in or close proximity to the town of Eureka2. There was a great increase in production in 1873 which was furnished by eight smelting works with a total of 17 furnaces2. There are now in Eureka (1876) nineteen furnaces, whose daily capacity varies from 40 to 60 tons each. The Lemon Mining & Milling Company has also erected a mill of 15 stamps1.
The average recoveries attained by smelting in 1874 were 81 to 83 percent of the lead and 82 to 85 percent of the gold and silver, based on the assay contents of the ore. The principal losses of precious metals occurred in dust and fumes, 8 to 10 percent, in the speiss 4.5 to 5 percent and in the slag, less than percent1.
Charcoal was used as fuel and it was the most important related business in the district. Annual consumption reached 1.25 million bushels per year and as many as 800 men were employed in charcoal manufacture. All the mountain ranges within a radius of 60 miles from Eureka were denuded of trees suitable for use in making charcoal1.
During the first years of smelting operations a number of small companies erected their own plants, but later the operators realized that the smelting rate charged by a large plant was less than the operating cost of a small individually owned one, so that eventually the smelting business reverted to the two major companies, the Eureka Consolidated and Richmond Consolidated1.
Up to 1877, all the base bullion (produced in Eureka) was shipped for refining either to Balbach Refinery in New Jersey or to the Selby Smelting & Lead Company at Selby, California. In 1877, the Richmond Company constructed a refinery for desilverizing bullion by the Lucien Rozan process, a modification of the Pattinson method. The lead was refined by successive crystallation in pots, into which steam was admitted. The silver-rich lead obtained in this manner was cupeled twice in wood-fired furnaces holding about 1 ton per charge1.
Site Investigation — NDEP and EPA are investigating the effects of historic smelting activity within the Town of Eureka on human health and the environment. Initial sampling conducted by NDEP and EPA in the Spring of 2012 indicate that slag piles present in town have very high levels of lead and arsenic. Additional sampling indicated that elevated lead and arsenic soil levels exist throughout much of the Town of Eureka.
Similar smelting operations have occurred in numerous towns across the western United States. In many of these towns, EPA and State agencies have conducted cleanup activities in order to reduce the threat posed by elevated levels of lead and arsenic.