Bingham Leaching and Precipitation Plants
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This page last updated on June 2, 2022.
(This research focuses on the site and location just west of present-day Copperton where Utah Copper, and later Kennecott Copper built a large preciptation plant in 1929, as well as a more modern plant in 1966. In early newspaper news items, this was referred to as the "Lead Mine precipitation plant," and later as the "precipitation plant near Copperton.")
The leaching process at Bingham started very early when miners discovered that scrap iron that lay in the runoff water from the mine dumps, and which flowed into Bingham Creek, very soon gathered copper from the water. It was a known chemical process, but not economical. First they used scrap iron placed in wooden barrels of creek water. Too slow and too labor intensive. Then in 1922 George Robbe discovered that if he laid tin cans in troughs and let the water run across the cans, they also gathered copper from the water, but at a much quicker rate. All that remained was to scale the process up, and make it economical, and the rest is history. The result was almost pure copper in the form a reddish sand-like material, known as precipitate. It went straight to the smelter; no milling at Magna required. It was also very profitable. I have an entire web page about it.
As early as 1915 Utah Copper tried precipitation to extract copper from mineral-rich waters that flowed from the base of mine dumps, as spring runoff water percolated down through what was in most cases ore that was too low grade to ship to the smelters. This run-off water was high in copper sulfates, which make the water a green color. The early attempts used scrap iron from around the mining camps, and recovered only about 40 percent of the copper that was in the water, and they stopped. In 1916 Utah Copper built a leaching plant at Magna to process the low-grade ore it was having to set aside as it was mining the higher-grade ore from its Bingham open pit mine. This lower grade ore, known as oxidized carbonates, was shipped to Magna and Utah Copper attempted to leach the copper by using large concrete vats and capturing the water. The process was labor intensive and expensive, and the Magna leaching plant was closed in 1921 at the same time that the entire Bingham mining operation was shut down due to low metal prices. The Magna leaching plant remained closed when mining at Bingham, and milling at Magna resumed a year later.
The basic technology today is known as "leaching," and works by capturing water that has run off of the waste rock piles. Mining engineers at Bingham were on the cutting edge in the 1920s developing the chemistry of getting the copper out of the water. It worked by putting the green runoff water in concrete tanks and adding large loose piles of scrap steel. The water is high in sulphuric acid as part of the leaching process, and the chemical reaction consumes the steel and removes the copper molecules from the water, allowing it to settle at the bottom of the tank, in the form of a dark red "sand". This is about 85 to 95 percent pure copper (along with small amounts of gold and silver), which was then loaded into rail cars and sent to the smelter. The process has been greatly refined and improved today, but the basic chemistry is the same; runoff water and needed "reagent" chemicals for a reaction that produces almost pure copper. No milling or smelting required.
In the early days, the leaching took place in piles of mined ore, usually in the waste dumps of low-grade ore that could not be sent to the smelters at a profit. The water was gathered in reservoirs, then piped to the precipitation plants. These precipitation plants were constructed with large concrete tanks, which were covered with wooden (later steel) structures to keep out the weather, and foreign materials that might slow down the reaction. Traveling cranes run the length of the structures, loading scrap steel from adjacent railroad gondola cars.
"Early miners observed that waters loaded with copper trickled out of the various waste dumps, and mine portals in Bingham Canyon. This was such common knowledge that downstream ranchers could recover copper from Bingham Creek. The creek had so much acid and copper in it that the water was undrinkable, but it did kill disease causing bacteria. Miners attempted to recover the copper in the various mine waters and from the creek itself by erecting precipitation plants. The first ones were not much more than a barrel or a tub (sometimes called "launders") placed near the mine portals or dumps. The chemistry of recovery was simple. The metallic iron added to the tub went into solution and the copper in solution precipitated out as metallic copper. Later precipitation plants used exactly the same chemistry, but at a larger scale." (Oquirrh Mountains Mining and the Environment by Eva J. Hoffman, U. S. Environmental Protection Agency, Denver, April 21, 2005, page 44)
"Around 1900, copper leaching and precipitation operations began in the canyon. Full scale copper leaching and precipitation operations were started around 1923 by the Utah Copper Company. Water not used or recycled by the precipitation process continued to flow down the canyon." (Oquirrh Mountains Mining and the Environment by Eva J. Hoffman, U. S. Environmental Protection Agency, Denver, April 21, 2005, page 5)
In 1922, George Robbe saw how the water from McGuires spring as it flowed from beneath the Utah Copper waste dumps had become unsafe for drinking, but carried large amounts of dissolved copper. He began development of a process using tin cans made of sheet metal, which were plentiful for his tests, after the tin and lead solder was removed from the cans, a process known as detinning. With help from his employer, Montana-Bingham mining company, he built the pioneering Robbe precipitation plant at McGuires Gulch, above lower Bingham (where the D&RGW depot was). He and his partner, Tom Billings, found more reliable sources for tin cans and sheet scrap metal at the numerous canneries that were operating throughout northern Utah, as well as scrap from the American Can Co. can manufacturing plant in Ogden. Their first shipment in August 1922 was over 30 tons of copper, that previously was lost in the waste dumps.
Utah Copper saw the success Robbe was having using water that he was leasing from Mrs. McGuire, and claimed ownership of the copper in the water, since it flowed from their waste dumps. They proved in court that although they had chosen not to process the low-grade ore in the waste dumps, they still owned whatever copper and other minerals that still existed in the ore, including copper that was in suspended in the water. They won the court case, as well as two later appeals. With the ownership of the copper settled, against Robbe and his employer Montana-Bingham mining company, Utah Copper proceeded to build test plants to fully develop Robbe's process. One plant was built on the site of the former D&RGW rail yard at Cuprum, on the canyon wall above Bingham. A second plant was built at the mouth of Bingham canyon on the site of the former D&RGW railroad siding known as Loline Junction, immediately west of their new company town of Copperton. Loline Junction was previously known as Lead Mine, a name that many residents continued to use for the homes and businesses that had grown up in the near vicinity.
Utah Copper’s precipitation plant at Lead Mine was completed in 1929 and was an immediate success. The plant was expanded on a regular basis and continued in operation by Utah Copper, and its successor Kennecott Copper, until it was replaced in 1966. The new plant used more efficient cone precipitators and remained in operation until 2000, when it was closed by Kennecott’s successor Rio Tinto. By this time, the waste rock being dumped had a much lower concentration of minerals, and the cost of pumping the copper-bearing water was found to not justify the benefits of recovering the small amount of copper leaching from the dumps.
Early Leaching Plants
The earliest efforts of precipitation at Bingham were to recover gold, and used the cyanide leaching process.
"Further development of the Bingham District was brought about by the New York and Utah Milling Company which built a leaching plant for lead treatment at Revere Switch in 1880. A roasting plant was added for primary treatment of the ores. Unfortunately no information remains concerning the success or failure of the plant." (The Economic and Social History of Bingham Canyon, Utah, by George Addy, BYU thesis, 1949, page 32, citing the 1880 U. S. Bureau of Census for the Tenth Census of the United States)
May 22, 1892
The first cyanide leaching plant at Bingham was constructed to treat low grade gold ore, which was plentiful at the time in the Bingham District. The building, 50 feet by 100 feet, was constructed "just below" (a short distance east of) the Rio Grande Western railroad depot at Bingham. The plant was equipped with crushers and roll mills, as well as tanks, which together had a capacity of 100 tons per day and reduced the ore to 75 to 85 percent of its assayed value. leaching was seen as the lowest cost method of reducing low-grade ore, if the ore was of the needed chemical composition. (Salt Lake Herald, May 22, 1892, citing the Bingham Bulletin)
October 7, 1894
"Changing the Niagara Mill. -- The Niagara mill at Bingham is being remodeled by the new owners of the Commercial and will he operated as a leaching plant upon the ores from the Commercial. The company will also build a half-mile of tramway from the mill to the mine, operations to commence at once." (Salt Lake Herald, October 7, 1894)
November 8, 1894
"Getting Ready To Operate. -- General Manager Heffron, of the Bingham Gold Mines Company, is of opinion that within next ten days the changes in the leaching plant being put in by his company for purpose of obtaining an easy method of reduction for the gold ores taken from the Commercial mine, will all be made within the next ten days and then the plant is to be placed in operation. It is of 100 tons capacity. The tramway from the mine to the mill has just been completed and the entire working force is now engaged in putting in the leading tanks." (Salt Lake Herald, November 8, 1894)
February 21, 1896
"Colonel H. G. Heffron of the Niagara Mining Company informs The Herald that there is some talk of again starting up the Niagara leaching plant for treatment of the oxidized ores found in that property, which runs about three ounces in silver and $5.50 in gold to the ton. The colonel uses the Kendall cyanide process, and mad4e a very successful run last summer." (Salt Lake Herald, February 21, 1896)
"Over the years of mining in Bingham old mine dumps have been made near the bottom of the gulches and such gulches have since been filled with oxidized overburden and sparsely mineralized waste rock from the Utah Copper pit. In the spring of 1919 George Robbe, chemist for the Montana Bingham Consolidated Company, observed a blue water percolating through the old mine dump at the bottom of McGuire Gulch and by analysis found it carried approximately thirty pounds of copper per one thousand gallons of water. He determined that the copper could be recovered as a precipitate of copper by introducing tin cans into the water. This method of recovering copper had been widely used in the Butte, Montana area but hadn't been economically applied to Bingham waters. Mr. Robbe then formed a partnership with Tom Billings to investigate the possibilities of the copper laden waters escaping and finally lost in the Jordan River." (Thomas P. Billings, History of the Bingham Mining District, 1952)
(Other sources show that George Robbe was a mining engineer, and worked for Montana Bingham as an assayer and clerk.)
Robbe and Billings built an early precipitation plant at the mouth of McGuire Gulch, higher up and a branch of Winnamuck Gulch, directly above the Rio Grande railroad depot in Bingham. The partnership used the Montana Bingham tunnel to access copper-bearing waters leaching from under the Utah Copper waste dumps higher up in McGuire Gulch. A legal battle soon developed with the both the Robbe-Billings partnership, and Utah Copper claiming rights to the copper-bearing waters, and therefore ownership of the copper. With a decision from the Utah Supreme Court, Utah Copper eventually won the court cases, thereby establishing ownership of the copper from its waste dumps no matter the form.
April 20, 1921
George Robbe was granted a lease on the waters from McGuires Dump. His first shipment of precipitates is dated August 21, 1922, and consisted of 100,460 net pounds of concentrates carrying 18.1 of H2O and 63,060 pounds of copper. (History of Utah Copper, compiled by L.F.Pett)
August 21, 1922
Robbe had taken the lease on the waters from McGuires dump on April 20, 1921. The whole development process had taken 17 months before the first copper from precipitation was produced on August 21, 1922. This first shipment consisted of 100,460 pounds of concentrates carrying 63,060 pounds of copper.
April 2, 1936
After building the earliest version of his copper recovery process in the vicinity of the mouth of Winnamuck Gulch, near the site of the D&RGW railroad depot at Bingham, using runoff water from the waste dumps in McGuire Gulch, Robbe abandoned his process in about 1926. On April 2, 1936, Robbe took a 10-year lease from Utah Copper for the copper-bearing waters of Bingham Creek, and built a recovery site along the creek east of Copperton. "The Robbe Cells were concrete containment cells approximately 600 feet long and 12 feet wide. Steel and wood gates were used to separate the concrete structure into cells. There are smaller test cells of similar construction just west of the main precipitation cells. According to Kennecott , operations ceased in 1958. (Another report [Kennecott Fact Sheet, 1997] indicates that the facility operated 1922-1936." (Oquirrh Mountains Mining and the Environment by Eva J. Hoffman, U. S. Environmental Protection Agency, Denver, April 21, 2005, page 49)
(The so-called "Robbe Cells" were located along the north side of Bingham Creek, about two miles east of the Utah Copper precipitation plant at Lead Mine. Aerial photographs of the area taken in 1940, and in 1964 show the location.)
October 1, 1958
Kennecott purchased the Robbe Precipitation Plant east of Copperton. For the previous twenty-two and a half years Kennecott had been leasing the plant from a private owner. (Kennecott Historical Index)
August 4, 1961
"George B. Robbe of Holladay [5619 Holladay Blvd. (1715 East)], graduate of Michigan Tech, and a retired Utah mining man, has been awarded an honorary Doctor of Engineering degree from his Alma Mater. He is credited with inventing the tin can method of precipitating copper from mine waters." (Bingham Bulletin, August 4, 1961)
April 9, 1963
"George Bernard Robbe, Salt Lake mining engineer, died Sunday (April 7) at 11:50 p.m. of natural causes in a Salt Lake hospital. Mr. Robbe was the inventor of a precipitation process for recovering copper from waters of springs containing dissolved copper salts. The process first was used in the 1920s." "Mr. Robbe was born on October 18, 1884 in Frenchlanding, Michigan." Apparently, Robbe and his wife Hazel did not have children. (Salt Lake Tribune, April 9, 1963)
Underground, in-place leaching of ore body. (1923-1931)
In summer 1922, Ohio Copper was developing its own method of leaching by preciptating sulfuric acid through its underground workings in Bingham canyon. The acidic water was pumped to the surface of the Ohio Copper claims along the east side of Bingham canyon, just east of the county road. The water then percolated down through the caved and otherwise broken parts of the underground ore bodies. The copper-bearing water was gathered in "launders" located in the company's Mascotte tunnel where the water was run over scrap iron. The first month of operation, October 1922, produced 26 tons of "wet" concentrated copper ore which was then sent sent to a local smelter.
In 1922 Ohio Copper company commenced leaching its copper ore body in place. Water was pumped to the top of the old caved stopes underground and distributed through them, being allowed to percolate through the broken ore, thus taking into solution the copper content. When the water reached the Mascotte tunnel level it was collected and the copper content precipitated by scrap iron and the water recirculated. This practice was highly successful, large amounts of copper being produced. For instance in 1927 production was 4,825,587 pounds of nearly pure copper. This operation was maintained till 1931 when the depression forced a shut down. The Ohio Copper property remained dormant till 1938 when a tailings retreatment plant was built at Lark. This plant was operating successfully in 1940. (The Economic and Social History of Bingham Canyon, Utah, by George Addy, BYU thesis, 1949, page 32, citing United States Geological Survey, Mineral Resources of the United States, 1927, page 665, and USGS Mineral Resources of the United States, 1931, page 568)
The following comes from the July 20, 1941 issue of the Salt Lake Tribune:
The mill (at Lark) employed gravity concentration from 1907 to 1918 and floatation during 1918. Recovery was less than 60 per cent. About 7,000,000 tons were treated before milling was suspended in 1919. This phase of the operations was unsuccessful although the mining costs of 2.3 cents per ton were a record for that time.
During the idle years of 1919 to 1923, examination of the accessible portions of the caved area of the mine disclosed that the entire surfaces of the tunnels and crosscuts were covered with crystals of copper sulfate. Ideal conditions for "leaching in place" being apparent, Mr. Goodwin continues, in 1923 the company entered upon the second phase, an innovation in the reclamation of copper until recently not duplicated elsewhere.
Bingham Creek water was pumped and distributed over the caved area and allowed to percolate down to the Mascotte tunnel where the copper in solution was precipitated on detinned scrap iron. From 1923 to 1931, more than 40,000,000 pounds of copper were produced by this method at a low cost of 6 cents per pound.
Since 1931 this method has been employed for a few years at a time between periods of rest when the caved area is allowed to oxidize further. Latest resumption of this leaching was late in July last year. (Salt Lake Tribune, July 20, 1941)
The following comes from the "History of the Bingham Mining District," an unpublished manuscript written by Thomas P. Billings in 1952:
The Ohio Copper, which adjoined the Utah Copper on the east and southeast was mining its orebody using the block caving system. With this system, as the mined ore is drawn from beneath the cap rock over the orebody the cap rock caves from surface and follows down upon top of the broken ore to be milled. This caving system developed huge holes at surface and the Utah Copper Company found it very desirable to build one of its tracks over the caved area for disposal of its overburden on surface available in the gulches below. So to establish a railroad grade it first had to fill in the huge holes produced from the Ohio's caving system and to maintain the track was currently filling the caves as the Ohio Company would draw the ore from below. Now in the agreement between the two companies covering this trackage the Utah Copper Company did not have the right of removal of the materials dumped by it into the caved area. For the maintenance of this trackage which was for a substantial period the Utah Copper Company dumped an immense tonnage of its overburden of oxidized copper ore into the caving area.
The Ohio Copper mine is connected to the Mascotte tunnel, 1000 feet vertically below surface, by a series of caved ground and mine workings, and the surface waters circulated freely through these caves and workings to the tunnel level where they were conveyed to the portal at Lark, Utah. (In 1922, Ohio Copper) constructed a small experimental precipitating plant that was successful during a brief period of the spring runoff. The Ohio Management, encouraged by the results, investigated the Robbe-Billings partnership operation of treating copper waters in Bingham and then proceeded to implement the leaching by natural causes of the oxidized copper minerals in the broken cap rock and Utah Copper fills by spraying with water pumped from the creek in upper Bingham. This percolating water dissolved the soluble copper minerals and on reaching the Mascotte Tunnel carried a comparatively high copper content in solution.
A large precipitating plant was constructed at a widened portion of the Mascotte Tunnel close to the bottom of the Ohio mine where the copper laden waters were collected to be conveyed to the plant. The problem of water supply to irrigate or spray the broken ore was solved by an arrangement with the Bingham Mines Company that was operating a lead-zinc mine and pumping into the Mascotte Tunnel from its workings below. This water was delivered to the Ohio Company and mixed with a portion of the tailing water of the precipitating plant then pumped through the Ohio incline shaft, of three compartments, to points on surface for spraying. The precipitating plant design was similar to the Robbe-Billings plant and larger. The detinned supply of can cuttings were shipped in 100 pound bales from California to Lark and there loaded into mine cars and hauled in the Mascotte Tunnel to the precipitating plant located about 12,000 feet from the portal. The copper precipitate or copper cement was pumped from the precipitating tanks into specially constructed mine cars, hauled through the tunnel to surface bins for loading into railroad cars on the Lark branch of the D&RG railway system and shipped to the Garfield smelter.
The Ohio leaching process was very profitable attained with relatively small capital expenditures but after a few years steady operation there was a gradual falling off in the copper content of the percolating waters collected at the tunnel level that threatened a continuation of the operation. Calculations of the probable amount of copper in the fills, and broken cap rock and ores showed that there should be considerable copper remaining susceptible to leaching. Sulfuric acid was then added to the spray water at surface to accelerate the leaching process and increase the copper content of the percolating water conveyed to the plant. This addition solved the problem temporarily but [by 1931 the process became] ineffective and unprofitable forcing suspension of operations. (Thomas P. Billings, History of the Bingham Mining District, 1952)
Ohio Copper Timeline
August 5, 1922
"The Ohio Copper Co. have recently acquired more water rights in Bingham and will improve and extend their present precipitation plant in the Mascotte Tunnel. The company recently purchased a carload of clippings and small pieces of tin cans from a firm in Ogden which have proven more lucrative than the cans which had accumulated rust." (Bingham Press Bulletin, August 5, 1922)
(This "firm in Ogden" was likely American Can Company, which had opened in Ogden in 1915, furnishing boxcars full of empty cans to Utah's large canning industry.)
August 24, 1922
Ohio Copper started its small-scale leaching operation by pumping 200 gallons per hour on the surface of an area of caved ore in its underground mine. The recovery of water at the end of its percolating cycle was 80 percent. The precipitated copper concentrate sent to the smelter was 89 percent copper. (San Francisco Examiner, January 7, 1923)
October 15, 1922
"As the result of a preliminary test of a plan to leach the Ohio Copper ore deposits in place, approximately 32 tons of wet copper precipitates were shipped from that property in the Bingham district for the week ended last night. The total shipments from the district for the was 86 carloads of ore." (Ogden Standard Examiner, October 15, 1922; the total excluded Utah Copper and Utah Consolidated, which made their production reports in their annual reports to shareholders)
December 29, 1922
"Experiments being conducted by the Ohio Copper at Lark and Bingham Utah are most interesting to the copper mining fraternity. Ohio has an area of broken ground, caved from previous mining operations containing approximately 37,000,000 tons with copper content of about 6 pounds per ton. A similar area in the property, if caved, will give a like amount of tonnage with the same copper content. This ore when broken oxidizes quickly making it possible to leach out copper values with water containing a small amount of dissolved sulphate. At present the company is pumping such water through the broken ore and thence into launders in its Mascot tunnel where the contained copper is being percipitated by scrap iron. Company is enlarging its equipment so that profits from this source by January should be about $10,000 monthly and it is planned to increase this to $25,000 monthly." (Butte Miner, December 29, 1922)
July 30, 1927
Ohio Copper was producing 400,000 to 500,000 pounds of copper each month from its leaching operations at Bingham. (Salt Lake Mining Review, July 30, 1927)
"Leaching of ore in place continued during 1930 at the property of the Ohio Copper Co. at Lark, but the production of copper decreased as it has done since 1924. In 1930 the output of copper recovered from precipitates was 2,048,369 pounds, compared with 2,215,178 pounds in 1929. Operations resulted in a loss of $52,724, due to the pronounced drop in the price of copper, although the cost of producing copper was reduced to 13.264 cents a pound." (USGS, Mineral Resources of the United States, 1930, page 594)
November 1, 1931
"Leaching of ore in place continued during 1931 at the Ohio Copper Co. property at Lark, but production of copper decreased from 2,048,369 pounds in 1930 to 659,213 pounds in 1931 (a drop of 66 percent). No development was done on the 700-foot level in the limestone area of the mine, and no efforts were made to treat material from the large tailings dump at Lark. Work for the year resulted in a loss of $44,963, and the property was closed November 1." (USGS, Mineral Resources of the United States, 1931, page 568)
Early Precipitation Plants -- Precipitation plants operated in Bingham canyon after it was discovered that copper in solution from mine wastes could be recovered by reaction with scrap iron. Following these discoveries, many small operations were installed in the canyon to precipitate the copper. Most were built and operated during the period 1913 - 1925. Many of the precipitation plants obtained the iron needed from Hewlett's Cannery in Salt Lake City and later from a source in California. These small operations included what was known as the McGregor Plant (1933-1936), which was replaced by the Robbe plant (1936-1958). (EPA Superfund Record of Decision: Kennecott South Zone Site, November 1998)
"Utah Copper’s early vat copper leaching at Magna eventually led to experimental leaching of the estimated 40 million tons of oxidized leached cap dumps at Bingham, running 0.3 to 1 percent copper, in the early 1920s. In 1928, a successful launder precipitation plant was constructed in Bingham Canyon. (Engineering and Mining Journal, 1928)
The Cuprum precipitation plant treated, on average, 1 million gallons per day, carrying 20 pounds copper per 1,000 gallons, recovering 97.5 percent, and producing a precipitate of 87 percent copper. During 1929, 4,420,460 pounds of copper were recovered from precipitates." (Kenneth A. Krahulec, History And Production Of The West Mountain (Bingham) Mining District, April 1998, page 31)
Magna Leaching Plant
April 28, 1914
Utah Copper announced that it would build a leaching plant to process the carbonate ore that the company was removing as part of the stripping operations of its mine. As the capping was being stripped from above the ore body, an average thickness of 114 feet, the portion of the overburden with sufficient qualities of low grade ore was set aside to be processed by leaching. By early 1914, the leaching process had been developed and plans were under way to begin construction of the leaching plant. (Ogden Standard, April 28, 1914)
December 31, 1915
"The Directors have authorized the construction of a leaching plant to treat the oxidized capping which has been, and is being, removed from the ore bodies. It is the intention to build this plant with an initial capacity of from 2,000 to 3,000 tons per day, the arrangement being such that this capacity can be readily increased, if an increase is warranted by the experience gained in the operation of the first installation. Construction on this plant will be commenced as early in the summer of 1916 as weather conditions and preparation of designs will permit. For the purpose of furnishing acid for this plant and supplying other local and some commercial requirements, the Company has undertaken to participate equally with the Garfield Smelting Company in financing the construction and operation of an acid works near the smelter." (Utah Copper 1915 Annual Report, dated December 31, 1915)
"In 1916, Utah Copper began construction on an innovative 2,000-tons per day vat leach plant at Magna, which treated their oxide ores from Bingham Canyon. Operating from October 1917 until December 1920, this facility used sulfuric acid, which was produced by the Garfield Chemical and Manufacturing Company, a 50/50 joint venture between American Smelting and Refining and Utah Copper. Successful early vat leaching operations at Magna, resulted in an experimental dump leaching program during early 1920's, which treated oxide material from leached cap (0.3 to 1.0% copper). The success of this program, lead to the commissioning of the commercial scale Cuprum precipitation plant in 1928." (David Briggs, Bingham Canyon, 2005)
July 1, 1916
"About the first part of July work will commence on the construction of the new Utah Copper Co.'s leaching plant. Plans have been completed and the site decided on. The initial capacity will be about 2500 tons and it is the intention to gradually increase the capacity as the work progresses. The plant will not be finished before the first of next year. The designs for the steel work, tanks and machinery have been completed. Just what the process of leaching is has not been announced. It will be by some use of sulphuric acid. For several years work has been carried on in the experimental department of the company for a process of leaching. A small plant has been running at the Magna plant for some time so that sufficient data has been secured for the construction of a commercial plant. About 40,000,000 tons of carbonate ore, carrying an average of 1% copper, has accumulated from the development of the mine. This has been a capping over the sulphide ores that are shipped to the mills. It is impossible to treat the carbonate ores by the same process as the sulphides, as the values will float off in the slimes and tailings." (Mining and Engineering World, Volume 1, Number 1, July, 1916, page 33)
September 12, 1916
"[In July 1916] Work was started the last of the month on the active construction of the new leaching plant." (Ogden Standard, September 12, 1916)
December 16, 1916
"The 100-ton sulphuric acid plant of the Garfield Chem. & Mfg. Co. started operations Dec. 1. It is backed by Utah Copper and American Smelting & Refining Co. The leaching plant of Utah Copper mill will not be ready until June 1, 1917. In the meantime Garfield Chemical expects to supply many leaching plants in Montana, Washington and Utah. The plant was constructed at the cost of more than $500,000 and within a short time will be producing 150 tons a day. It has in connection a concentrating plant, which, with the original plant, will produce three grades of sulphuric acid." (Mining and Engineering World, Volume 1, Number 25, December 16, 1916, page 1051)
December 31, 1916
"In order to furnish acid for the leaching plant and mills, as well as to supply some other local and commercial requirements, the Company agreed to participate equally with the Garfield Smelting Company in the construction and operation of an acid plant near the smelter. The construction of this plant was begun on March 8th, 1916, and the work was far enough along by December 22nd, 1916, to permit commencement of acid production." (Utah Copper 1916 Annual Report, dated December 31, 1916)
February 12, 1917
Ogden Standard newspaper published a detailed description of the yet-to-be-completed leaching plant at Magna.
Utah Copper Porter locomotive no. 36 and several waste rock dump cars were sent from the Bingham mine to the newly completed Magna leaching plant to be used in the removal of tailing from the leaching process, "from the vats to the dump." The leaching ppant closed in January 1919 due to cold weather, but the railroad equipment was retained at the leaching plant. No. 36 was transferred from mine ownership to B&G ownership, with an accounting value of $4,100.00. Porter 0-4-0 saddle tank locomotives 5 and 6 were already assigned to the Magna mill for miscellaneous switching duties, and were also used at the leaching plant, although their capacity limited their usability. (Internal Utah Copper written communications)
A 2,000-ton leaching plant was completed at Magna to recover copper from very low grade (less than 1 percent) ore. Construction started in August 1916. (Kennecott notes; Engineering & Mining Journal, July 1, 1916, page 71)
October 1, 1917
"A leaching plant was built at Magna and the first vat filled on this date. The plant continued operating until January 17, 1919 when it closed, to reopen again on July 17, 1920, and to be closed December 13, 1920, on account of freezing weather. A final cleanup of the precipitates was made in August 1921, the plant being idle since that time." (Utah Copper Chronology, citing a History of Utah Copper compiled by L. F. Pett)
Operations of new Magna leaching plant began. (Kennecott notes)
The book The Utah Copper Enterprise was published in 1919, and included a full description of the recently completed leaching plant at Magna.
Utah Copper Porter locomotive no. 37 was sent from the Bingham mine to the Magna leaching plant to be used in the removal of tailing from the leaching process, joining no. 36 and other waste rock cars already assigned to the site. Utah Copper purchased four Western air-dump high-side cars specifically for leaching plant service, to handle the 4,000 tons per day of tailings being produced at the plant. The dump cars were 26 feet long and held 30 cubic yards (48 tons). The tailings were moved to the dump in either 10 or 11 four-car trips per day, powered by one of the locomotives. (Internal Utah Copper written communications)
Magna leaching plant was shut down permanently due to the low price of copper, and the high cost of the leaching operation. The plant was under construction between September 1916 and September 1917, and was in operation from January 1918 to February 1919, and again in May 1920 through February 1921. (Kennecott notes)
Utah Copper Porter locomotive no. 36 was returned to the Bingham mine upon the closure of the leaching plant. No. 37 and the four Western waste rock dump cars remained at the leaching plant as part of the final cleanup of the closed site, and were returned to the Bingham mine in July 1922. (Internal Utah Copper written communications)
Tiewaukee (Winamuck) Dump Precipitation Plant
Utah Copper built a small precipitating plant about 200 feet north of the Denver and Rio Grande Railroad depot in lower Bingham. The plant was built to recover copper from Utah Copper dumps in Winamuck Gulch. (Oquirrh Mountains Mining and the Environment by Eva J. Hoffman, U. S. Environmental Protection Agency, page 55)
By 1919 Utah Copper had already dumped 20 million tons of waste rock into Tiewaukee, McGuire and Little Eddy gulches. Utah Copper had planned to send the copper water from these dumps to a leaching plant in the valley. This apparently did not happen because Robbe acquired leaching rights to McGuire Gulch in 1923. (Oquirrh Mountains Mining and the Environment by Eva J. Hoffman, page 85, citing Rickard, 1919)
In 1925, the Ute Copper Company owned the underground mineral rights under the Tiewaukee Dump. They drove a raise to the bottom of the overlying dump and diverted water to precipitation boxes. Although Utah Copper owned the surface rights and the dumps, the Ute Copper Company intercepted the water by extending their underground tunnnel in bedrock and diverted the copper laden waters from underneath. The water flowing down Winamuck Gulch from the Utah Copper waste dumps were diverted from the gulch into the old Tiewaukee mine workings. The water flowed to the lower tunnel, where the precipitating plant was located on the old mine dump at the portal of the Tiewaukee lower tunnel. Utah Copper then drove tunnels of their own in Winamuck Gulch to intercept the water. The competing companies engaged in a race with their competing tunnels. The Supreme Court later ruled that this water belonged to Utah Copper. The Tiewaukee Dump was located in Winnamuck drainage approximately one-half mile below the confluence of Carr Fork, and Bingham Canyon. An internal Utah Copper memo from 1937 indicated that the cost of the plant was $5100. Later, waters from this operation were combined with waters from other dumps at a central plant in Cuprum. (Oquirrh Mountains Mining and the Environment by Eva J. Hoffman, page 50)
Bingham Open Pit Mine Leaching Plant
A test precipitation plant was built in the bottom of the pit to recover the dissolved copper in drain water which collected at the bottom of the pit. (Arrington and Hansen, "Richest Hole on Earth," 1963, page 74)
In 1923, Utah Copper began experimenting once more in an attempt to recover the copper in the accumulating mine dumps. It had been noticed that rain and snow percolating down through these dumps emerged greenish-blue. Investigation indicated that some of the copper exposed in the waste rocks had been oxidized into a form soluble in water. Company engineers and scientists soon found a cheap and effective way of extracting this copper by placing metallic iron in the solution and allowing the copper to trade places with the iron. The copper would precipitate out in the form of copper mud, while the iron went into solution. By this process, the company hoped to recover approximately 1,000,000,000 pounds of copper from the otherwise worthless dumps. To make this possible, Utah Copper set up a test plant at the bottom of the pit in 1923. An improved precipitation plant was erected in 1924, followed by still another which operated successfully until the present plant (at Copperton) was built in 1929.
Cuprum Precipitation Plant
The Cuprum precipitation plant (or Utah Copper Central Precipitation Plant) was located on the hillside east of Central Yard. The site was the former D&RGW Cuprum rail yard, which was wide enough to accommodate four tracks.
October 6, 1928
"Operations at the new plant began on March 26, and, during the period to June 1, the average flow treated was 1,000,000 gal. in 24 hours. Plant heads averaged 20 lb. of copper per 1,000 gal., from which an extraction of 97.5 per cent was made, tailing averaging 0.5 lb. of copper per 1,000 gal. The average grade of precipitate produced was 87 per cent copper. Contents of the company's dumps on the mountainsides and in the canyon gulches near the Bingham mine are estimated to be 87,000,000 cu.yd. The copper assay value of the various dumps ranges from 0.3 to 1 per cent, 50 per cent of the copper being in the form of chalcocite, 30 per cent covellite, and 20 per cent chalcopyrite.... Detinned iron scrap, which is used as the precipitating agent, is heaped into the upper chamber of the boxes.... Consumption of this scrap is 1-1/4 lb. for each pound of copper precipitated.... Precipitate in the settling tanks is allowed to accumulate to within 4 ft. of the top of the tanks, the water in the tanks overflowing at this elevation through slots at the foot, and then passing in launders to join the tailing flow from the plant. This mixture of plant tailing and overflow from the settling tanks is conveyed by a wood-stave gravity pipe line to the Bingham Canyon sewerage system." (Engineering Mining Journal, October 6, 1928, pages 534-536, research completed by Steve Richardson)
"An internal Utah Copper memo from 1937 indicates that a precipitation plant was built at Cuprum Yard during 1927 and 1928. It was built to serve as a central plant with pipelines laid so that all the upper waters could be handled in one plant. The Cuprum Precipitation Plant was located on a hillside east of the current central yard near the Bingham Mine Truck Shop on the northeast margin of the Bingham Pit. The plant was a precipitation plant that extracted copper from waters that had passed through waste rock. Operations begin in 1928 and continued through the 1930s. Detinned scrap iron was used as a precipitating agent. Tailings and overflow from the settling tanks was conveyed by a wood-stave gravity pipeline to Bingham Creek. The site is near the edge of the pit; a portion has been mined away and another portion is under the dumps. The only remaining remnant of the site are some cement pillars. The date of demolition is not known." (Oquirrh Mountains Mining and the Environment by Eva J. Hoffman, U. S. Environmental Protection Agency, Denver, April 21, 2005, page 56)
A review of available photographs shows that the Cuprum precipitation plant, with its very long building covering the vats, was in place on November 10, 1930 at the site of the former D&RGW rail yards (Bingham 84; Larry Sax 195). By the time of another photograph of the same area (UCM-184), dated April 23, 1940, the structure had been completely removed and the tracks changed.
A large concrete retaining wall had been built during the 1920s to hold back the Cuprum rail yard embankment, and was an obvious visual feature in photos of th era, being located directly across the canyon from the B&G steel bridge which itself spanned Carr Fork. This large concrete retaining wall remained in place well into the 1960s.
Lead Mine Precipitation Plant
The following comes from a 1939 history of Utah Copper Company:
As mined, ore with less than 0.25 percent copper in sulphide form is not soluble. But after remainig in exposed dumps for three or more years, copper sulphides change to soluble copper salts. Much of Bingham's 15.5 inches of precipitation falls in the form of snow. During spring, melting snow water percolating through the loose dump material, gathers in solution soluble copper salts. This water emerges at the toe of dumps, differing in color from pale blue green to almost black, depending upon the amount of copper salts gathered along its path.
It was early observed that coins or pieces of iron placed in these colored solutions were rapidly coated with pure copper. The first practical application of the replacement or precipitation principle at the mine was begun during 1915. This was of an experimental nature and only partially successful. The copper water was run through wooden boxes filled with heavy junk iron. Successive coats of copper were brushed from the iron and the precipitate shoveled into barrels. Recovery averaged about 40 percent, with the grade of precipitates running about 30 percent copper. Yearly production, following these experiments, amounted to about 20,000 pounds per year until 1922, when recovery of copper from waste dumps became more than an experiment.
Water tunnels were driven into the gulches below dumps to collect the copper bearing water. Copper banded wood stave pipe lines lead to small plants of the wood box variety. These plants showed marked improvement and demonstrated the advisability of constructing a central plant capable of handling water from all gulches. Accelerated action which followed replacement of heavy scrap iron with thin sheets of detinned scrap iron was also demonstrated.
Construction of the Lead Mine Plant near the mouth of Bingham Canyon was begun late in 1928. Collecting lines along Main Canyon and Carr Fork were increased in size to accommodate streams, which each intercepted, until lines joined near the lower end of Bingham. From this point, two 14 inch copper banded wood stave lines lead direct to the central plant at Lead Mine.
This plant, housed in the longest building in the world according to "Ripley", is 1520 teet long. The west portion ot the building, 63 feet wide and 544 feet long, is used as storage for scrap iron, while its east portion, 50 teet wide by 976 feet long, contains four parallel rows of concrete precipitating vats. Each vat, four feet wide by four feet deep, follows a grade of 0.8 percent throughout the full length of 960 feet. Vats are divided into 80 foot sections with by-pass valves at each end tor diverting water during washing. Baffles, made of boards at each 20 teet, regulate the depth and circulation ot water. A false bottom of wood lattice rests 18 inches above the floor, allowing copper precipitates to settle below the scrap iron. Vats are loaded with detinned scrap iron as a precipitating medium.
Detinned scrap received at the plant in open cars is unloaded by crane from two tracks which extend the full length of the storage space. Track space is used for storage as side alcoves become filled. Electrically operated tram rail cranes are used in transferring scrap from shed to vats. Cranes have carriers, with two forks attached, each capable ot picking up and transporting 1000 pounds of iron. An operator rides inside the cab of the cranes.
Production and percent of extraction is much higher in the first ftew 80 foot sections, so that washing or cleaning of these sections is required often. This is acccmplished by closing intake gates, draining the copper water into settling tanks, am flushing with fire hose connected to fresh water supply lines.
Two pairs of men, each with a flush hose, scour an 80 toot section in about two hours, washing from five to ten thousand pounds of copper precipitates from vats to settling tanks.
Concrete settling tanks, 24 feet wide by 7 teet deep, built on a 1 percent grade, extend the full length of 960 feet. Copper bearing water reaching tanks during washing operation is returned to vats by a portable pump. Tanks are divided into 40 foot sections. A traveling crane, with clam shell bucket, is used to load precipitates from tanks to cars. Cars are spotted on a loading track which parallels the outside of settleing tanks. (History of Mining at Utah Copper, 1939, pages 177-185)
(Between 1916 and 1922, it was estimated that copper recovery by replacement, or preciptation, totaled 200,000 pounds of copper. In the first year of operation of the Lead Mine plant, 609,753 pounds of copper was recovered, and the total steadily increased to 7,704,362 pounds in 1939. During 1939, a total of 871,466 gallons of "impregnated" water flowed through the plant, with over 98 percent recovery of the copper content. A total of 7,434,362 pounds of copper was produced by precipitation during 1939.)
To augment mining operations, a Precipitation Plant was built in 1929 at the mouth of Bingham Canyon following six years of testing methods of recovering trace amounts of copper from waste rock. A revolutionary Cone Precipitation Plant, developed by Kennecott engineers, augmented leaching operations near Copperton in 1966 and replaced the original plant. (Kennecott Utah Copper Centennial, 1903-2003)
Early April 1929
"The new precipitation plant at the mouth of Bingham canyon was placed in operation in early April. The plant has a capacity of more than 5,000,000 gallon of copper-bearing water a day and makes a recovery of about 97 percent of the copper." (Ogden Standard Examiner, January 19, 1930)
May 9, 1929
Precipitation Plant Boosts Copper Output -- Bingham, May 9 (Special) -- Copper output of the Utah Copper company is being materially increased by the new precipitating plant near Copperton, at the mouth of Bingham canyon. It is estimated that 5,000,000 gallons of water, which contains about sixteen pounds of copper per 1000 gallons, passes through the plant every twenty-four hours, yielding fifty tons of the red metal." "The water is run onto the dumps of waste removed by the power shovels in mining the ore from the Utah copper property and is carried in a pipeline to the precipitating plant. The building housing the plant is one of the longest in the state, having twelve sections, each 80 feet long (960 feet)." (Salt Lake Telegram, May 9, 1929)
(During the 1930s and 1940s, newspaper news items regularly referred to the precipitation plant near Copperton as the "Lead Mine precipitation plant.")
(Research suggests that by the 1940s, the precipitation plant at Lead Mine, immediately west of Copperton, was the only precipitation site used by Kennecott Copper at its Bingham mine.)
Cement copper production at the Lead Mine Precipitation Plant totalled 15,481,465 pounds. (Mines Annual Report 1954, page 4)
Cement copper production at the Lead Mine Precipitation Plant totalled 11,841,006 pounds for the year. (Mines Annual Report 1955)
February 27, 1955
"This additional [spring runoff] water, seeping through the waste material, can really bring down copper. Under normal leaching operations, some four to six million gallons of water are percolated through the huge waste dumps every 24 hours. When a heavy spring run-off hits. as much as 11 million gallons of copper-containing water can be processed through the precipitation plant at the bottom of the canyon during the same period. Precipitate production of eight pounds of copper per 1,000 gallons of copper-bearing water at the collection plant can be increased during the same period." (Ogden Standard Examiner, February 27, 1955)
"Pictures of the precipitation plant launders available in Kennescope [May, 1956 and Nov, 1958] show extensive use of concrete troughs [launders] and long settling tanks. The 1958 article said the launders were four feet deep, four feet wide, and 960 feet long. An attached shed for storing scrap iron and unloading rail cars carrying the scrap iron was 550 feet long. The product, copper mud, was 75 to 90 percent copper. The better grade concentrates were sold directly to paint pigment and powder metallurgists, the remainder was shipped to the smelter for further refining." (Oquirrh Mountains Mining and the Environment by Eva J. Hoffman, U. S. Environmental Protection Agency, Denver, April 21, 2005, page 46)
March 2, 1958
"Dump leaching and precipitation plant operation is set up as a separate department to be headed by a general leaching foreman." (Salt Lake Tribune, March 2, 1958)
Operation of precipitation plant produced 20 million pounds of copper, about 5 percent of 1962 production. (Arrington: Richest Hole, page 74)
November 2, 1962
Kennecott announced that a tunnel (2,100 feet in length) was to be driven under the waste rock filling Dry Fork Gulch, with its purpose being to gather water that was leaching through the waste rock. This leach water had a high concentration of copper and would be moved in a pipeline to the precipitation plant at Copperton. The tunnel would be 6 feet by 8 feet. A new water reservoir had been completed and new pumping systems were in place to pump water to the top of the Dry Fork waste dumps. In its current operations, Kennecott was dumping 235,000 tons of waste rock every day. The tunnel was expected to be completed in March 1963. (Bingham Bulletin, November 2, 1962)
The 1962 production of this leaching plant was approximately 20 million pounds of copper which is almost five percent of the total 1962 production. Kennecott (1996) reports that the concrete launders were demolished in 1965. (Oquirrh Mountains Mining and the Environment by Eva J. Hoffman, U. S. Environmental Protection Agency, Denver, April 21, 2005, page 46)
January 23, 1963
"O'Keefe also said production of precipitate copper from the waste dumps at the pit would be gradually expanded to approximately 6,000 tons per month. He said this will require expansion of the company's precipitation plant located near Copperton, Utah. Precipitate production is now running 1800 tons per month. The precipitation plant produces copper through a means of leaching." (Provo Daily Herald, January 23, 1963)
April 7, 1963
"Setback Brings Progress at KCC Plant" "Bingham Canyon -- Kennecott Copper Corp. has turned a setback into progress. Two months after a gust of wind flattened much of it, the Utah Copper Division precipitation plant is back near peak production and with many improvements. Immediately after the damage, some copper-bearing water was diverted temporarily to a stand-by plant or to bypass lines to avoid flooding and facilitate cleanup. Copper precipitate production at the stand-by plant averaged 4,000 pounds daily during a 10-day period, compared to the normal run of about 100,000 pounds daily at the regular plant. Four days after the big wind, 50 per cent of the damaged plant was cleared and back in use, producing more than 11,000 pounds of precipitate daily. Present precipitate production is averaging more than 100,000 pounds daily. Prior to the storm, huge piles of de-tinned scrap iron, used as a precipitant, were carried into the plant by overhead tramway cranes. Now, fork-lift equipment and mobile cranes are used to move the scrap more efficiently and at less expense. Because travel space no longer is required under the roof for tramway cranes, larger tonnages of iron can be stored at the plant. Lifts and cranes, unhampered by walls and roofs, can move more rapidly and with more flexibility along the troughs than could the tramway cranes. During cleanup and repair, a concrete center aisle between the trough sections was reinforced to take a load limit of 12-1/2 tons imposed on it by the movement of the lifts and smaller cranes. Further improvements in the plant will result in average daily production of 150,000 pounds of precipitate by mid summer. (Salt Lake Tribune, April 7, 1963)
(The wooden roof of the precipitation plant collapsed from unknown causes, although a strong gust of wind was suspected as the cause. The wind gust apparently entered the western end of the building, and exited the eastern end, collapsing about 800 feet of the 1000 feet of wooden roof boards. -- Provo Daily Herald, February 3, 1963)
January 11, 1964
"Key to the [1964 expansion] program is the expansion of the precipitation plant at the mouth of Bingham Canyon, which will boost precipitate copper production by 4,200 tons to 6,000 tons monthly, according to officials. The process uses a new type of cone precipitator developed by Kennecott at its research center at University of Utah and is capable of recovering copper from overburden or waste material." (Salt Lake Tribune, January 11, 1964)
Bechtel Corporation was awarded contract to build new $4 Million precipitation plant at Copperton. (Kennescope, March/April 1965)
February 11, 1965
"Kennecott Copper Corp. has awarded a $4 million contract for construction of a new precipitation plant near the mouth of Bingham Canyon. The contract went to Bechtel Corp. of San Francisco. General Manager J. P. O'keefe said this is the final major contract for Kennecott's $10 million, four-year project begun in 1963." (Ogden Standard Examiner, February 11, 1965)
March 22, 1966
"The Watered-Down Copper Story" "The old art of recovering copper from mine dump water and scrap iron will become an exact science when Kennecott completes its new $20,000,000 precipitation plant near the Bingham Canyon mine. About all that will remain of the old plant will be the chemical principle that changes scrap into copper. When treated mine water flows into long troughs over the scrap iron, a surprising chemical reaction takes place ... the iron goes into solution and the copper comes out. Through extensive research, Kennecott has speeded up the chemical reaction with 26 specially designed precipitator cones. Instead of dumping scrap iron into troughs, it will be fed automatically into the top of the cones. Meantime, the mine water solution will be forced, under pressure, from the bottom of the cone and will be swirled through the scrap iron. The result will be the treating of more material in less time with greater recovery of copper. This will make it possible for Kennecott to compete more successfully in the world-wide copper market by increasing its precipitate copper production from 2,250 to 6,000 tons per month. (Salt Lake Tribune, March 22, 1966, Kennecott Copper Corp. advertisement)
The new cone precipitators made use of a new processes patented by Kennecott:
Proler Steel Corporation began construction of scrap metal de-tinning plant at junction of old Bingham highway and Lark highway. The plant will furnish scrap iron to new precipitation plant. (Kennecott Historical Index)
The process included taking scrap steel cans "tin cans" and passing them through an open-flame oven to burn off the tin coatings and solder, and any other foreign material, to produce a raw steel product that could be used in Kennecott's precipitation plant at Copperton. The scrap "tin" cans arrived by rail car at Proler's facility, and after processing were re-loaded into rail cars for their trip to the precipitation plant. In early 1991, officials in the city of San Jose, California, were concerned when they found out that cans from the city-wide recycling program, instead of being recycled as new steel cans, were being sent to Utah to be sprayed with sulfuric acid solution, and used to produce copper concentrate in the precipitation process. In fact, the steel cans were totally recycled, at the elemental chemical level, from steel to almost pure copper by the precipitation process in which water that had been sprayed on the waste dumps of the copper mine, and after becoming a mildly acidic copper-sulfate solution, was being gathered at the base of the dumps and in-turn being sprayed on the scrap iron. The process completely consumes the scrap iron, leaving behind almost pure copper. Three pounds of steel produces one pound of copper. (part from Deseret News, April 21, 1991; April 28, 1991; May 12, 1991)
Two 70-ton diesel-electric locomotives were transferred from Nevada to operate as switchers at the new precipitation plant at Copperton. (Kennecott Historical Index)
The following comes from a 1994 U. S. EPA report:
For many years, Kennecott has operated a precipitation plant which employs a cementation process to extract copper from aqueous solutions. The precipitate plant contains 12 cones and operates on a continuous basis. Annual precipitate production in 1985 was 6,000 tons (Kennecott 1992).
At Kennecott's precipitation plant, the pregnant solution flows through a cone precipitator filled with iron shavings that works similar to a cyclone (U.S. Congress, Office of Technology Assessment 1988).
The precipitation system consists of a cylindrical wooden tank (measuring 6 to 7 meters high and 4 to 6 meters in diameter) in which a 4-meter-long stainless-steel cone is fixed (apex down). The upper third of the cone is constructed of stainless steel screen. The [leach solution] is swirled into the cone via openings in two rings attached to the inside of the cone (the openings are one-third and one-half the way up the cone's side). The PLS swirls upwards through the shredded iron scrap, causing the copper to precipitate (Biwas and Davenport 1976; U.S. EPA 1989e).
The swirling action washes the copper from the iron surfaces, and the particles become suspended in the solution. The copper particles are carried upwards to near the top of the cone, where, as the velocity decreases due to increased cone width, they sink through the screened section into a collection area at the bottom of the tank. Kennecott's cone system is a high-capacity unit, which can handle up to 10 cubic meters (m3) of solution per minute. Furthermore, the system is flexible, and two or more cones can be placed in series to maximize copper recoveries and/or handle solutions with high copper concentrations. Finally, an additional advantage of this system is that it has a low iron consumption rate (Biwas and Davenport 1976). (U.S. Environmental Protection Agency, Technical Resource Document Extraction And Beneficiation Of Ores And Minerals, Volume 4, Copper, August 1994, page 1-133)
"In 1981, Kennecott reported that the precipitation plant consisted of two cone modules, or structures, each housing 13 cone units. The modules are operated in parallel. Each of the 26 cones is designed to process copper bearing solutions through shredded scrap iron. The scrap iron is combined with the solution in the cones to react on a continuous basis to produce a solid copper precipitate. The copper precipitate slurry is discharged at pre-set intervals into a thickener. The thickened slurry is then pumped to a surge mixing tank. Precipitate slurry is pumped from that tank to filter presses for dewatering and drying. The precipitate material is then conveyed to a loading and storage building where weighing, sampling and loading for smelter delivery takes place. Tailing solution from the cones passes in parallel through two 140 foot diameter settling basins. The overflow goes to the sump of the central pump station where it is recirculated throughout the leaching system." (Oquirrh Mountains Mining and the Environment by Eva J. Hoffman, U. S. Environmental Protection Agency, Denver, April 21, 2005, page 47)
"In 1986, the production of copper from the leaching operations was estimated at 11 percent the total [Kennecott, 1984]. The active facility consists of upright redwood tanks. (Oquirrh Mountains Mining and the Environment by Eva J. Hoffman, U. S. Environmental Protection Agency, Denver, April 21, 2005, page 46)
The was a news story in 1991 that the City of San Jose, California, was upset that their recycled cans were not being "recycled" by their definition, i.e., melting them down to make more steel. They found that their cans were being shipped to Utah, burned to remove tin, and sprayed with acid, to produce copper. The ultimate recycling, steel to copper.
During 1995, Kennecott built a pilot plant to test the Solvent Extraction/Electrowining process. The pilot plant was located at Dry Fork and was closed in 1998. A new Solvent Extraction/Electrowining plant was constructed at Copperton in 2008, and replaced the existing precipitation plant. (Utah Air Quality Control Board comment sheet dated August 4, 2008)
"What Was Once Profitable Is Profitable No More -- Early in the century, it was discovered that the water in Bingham Creek contained a bunch of copper. Drop some iron into the water and it turned blue as the copper plated itself to the iron. Some enterprising Kennecott worker figured out that there was copper -- and money -- being sent down the creek and in the mid-1920s, a small precipitation plant was built to recover the copper.
"In the 1950s, a more aggressive approach was taken where water was actively pumped onto the dumps. At that time, it was possible to recover 16 to 18 pounds of copper per thousand gallons of water. That represented good money. But, over time, the productivity of this process has declined. Today, 1.3 to 1.4 pounds of copper is recoverable per thousand gallons of water. Given the cost of pumping (there's 25,000 gallons a minute pumped) and other considerations, the precipitation plant has become uneconomical. In fact, one can say that the nature of the plant has changed from being a metal recovery system to becoming a water management system. It has been decided to stop the active pumping of leach water onto the dumps -- we will no longer be in the business of pumping and treating leach water -- which will drastically reduce our power and iron consumption." (KEEP Program summary, dated September 8, 1999)
"The precipitation plant was closed in 2000 with the cessation of active dump leaching. The facility is scheduled for demolition and cleanup in 2005." "Kennecott ceased active leaching operations in the fall of 2000." (Oquirrh Mountains Mining and the Environment by Eva J. Hoffman, U. S. Environmental Protection Agency, Denver, April 21, 2005, page 48, 93)
"Several other historic facilities underwent demolition and reclamation during this year including a pump house, inactive portions of the Precipitation Plant, and the Bonneville Crushing and Grinding facility." (Kennecott 2006 Sustainability Report)
During 1995, Kennecott built a pilot plant to test the Solvent Extraction/Electrowining process. Located at Dry Fork, the pilot plant was closed in 1998. In 2008, a production Solvent Extraction/Electrowining plant was constructed at Copperton, and replaced the existing precipitation plant. (Utah Air Quality Control Board comment sheet dated August 4, 2008)
- Historical Notes On Mill Sites In Bingham District, by Steven Richardson, November 1995
- Oquirrh Mountains Mining and the Environment by Eva J. Hoffman, U. S. Environmental Protection Agency, Denver, April 21, 2005) (PDF; 343 pages; 84MB)
- History of the Bingham Mining District, Thomas P. Billings, 1952