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By Fangtian Wang

The fully mechanized longwall mining was employed in a shallow coal seam that was under the gobs of room and pillar mining and overlain by thin bedrock and thick loose sands. Operational practices have demonstrated that severe accidents would occur including roof structure instability, roof steps, damages of shield supports, and face bumps triggered by the large area roof weighting, resulting in serious threats to the safety of underground miners and equipment. This paper uses Shigetai Mine, located in the Ordos area, Inner Mongolia, as the study site. It fully considers the geological conditions of 3-1-2 coal seam and employs theoretical analysis, 3DEC numerical simulation, and field measurements to analyze the overlying strata movement for the shallow seams under an abandoned room and pillar mine without pillar extraction. The research results serve as an excellent guide to mining in similar geological and mining conditions.

Jan 1, 2014

By David F. Gearhart, Khaled M. Mohamed

"Trusses are primarily used as passive roof supports in coal mines. They are constructed of three main parts: two grouted bolts installed at opposing forty-five degree angles into the roof so that they are anchored over the ribs and a cross member that ties the angled bolts together. There is also hardware used to assemble these components. The capacities of the angled bolts are typically 30 to 40 tons and the tensile capacity of the cross member is also 30 to 40 tons. Importantly, the direction of the immediate roof loading on the cross member is unlike the direction of the loading on the angled bolts. The load on the cross member is transverse to the longitudinal axis instead of along it, and therefore the cross member is loaded in the weakest direction.Previous tests conducted on truss systems applied loads such that the increasing tension in the two diagonal bolts increased the tension in the horizontal cross member, resulting in a stiff response. By contrast, if the load is applied directly to the cross member, which then transmits those forces to the diagonal bolts, it results in a much softer response.Based on this difference, laboratory tests to apply transverse loads and measure the vertical load capacity of three different types of cross members were conducted using the Mine Roof Simulator (MRS) located at the National Institute for Occupational Safety and Health (NIOSH) in Pittsburgh. The length of the samples was about 16 feet. Single-point load tests, with the load applied in the center of the specimen were conducted to verify the performance of the test arrangement and the finite element models. Double-point load tests, with a span of eight feet, were also conducted. This arrangement replicates the performance of the cross members with a distributed load. Both of these test arrangements were conducted on one-inch-diameter threaded steel bars and 0.7-inch-diameter cable and 0.6-inch-diameter cable cross members.For the single-point load configuration, the yield of the one-inch bar was nominally 22 kips of vertical load, achieved at 17 inches of deflection. For both sizes of the cable cross members, yield was not achieved even after 18 inches of deflection. Peak vertical loads were about 20 kips for the 0.7-inch cables and 15 kips for the 0.6- inch cables. For the double-point load configurations, the one-inch bar cross members yielded at 33 kips of vertical load and 10 inches of deflection. The 0.7-inch-diameter cable cross members broke strands at 30 kips of vertical load and 10 inches of closure, and the 0.6-inch-diameter cable cross members broke strands at 25 kips of vertical load and 10 inches of closure. Finite element models of each of the six different configurations were developed and show the variation of the vertical capacity of the cross members and the difference of the behavior of the bar versus the cables."

Jan 1, 2015

By J. A. Cremeens, D. D. Overton, J. C. Varnier

"Slope failures that occurred in 2008 and 2009 at the Pikeview Quarry in El Paso County, Colorado, USA were investigated using three-dimensional discrete element modeling methods. Large scale block sliding failures occurred along weak bedding planes that dip steeply into an excavation located at the toe of the slope. Several mining sequences at the toe of the slope were simulated to evaluate the effects of various degrees of extraction and backfill on slope stability. Slope stability back analysis was conducted using pre-failure and post-failure conditions to determine the joint shear strength properties. Laboratory testing was also conducted to determine intact rock properties. Three-dimensional discrete element analysis was uniquely applicable to this evaluation because it allowed representation of shear stress of the basal sliding surface and it afforded evaluation of several scenarios of extraction and backfill at the toe of the slope. INTRODUCTION The Pikeview Quarry is an aggregate quarry located approximately five miles northwest of Colorado Springs in El Paso County, Colorado, USA. The quarry has been operated by several owners since the early 1900s. The Pikeview Quarry has been a major source of construction aggregate for the Colorado Springs area for many years (MSHA 1986). In the 1950s, the site was mined by Peter Kiewit and Sons to provide limestone for the construction of the nearby Air Force Academy. A large scale slope failure occurred on December 2, 2008, which stopped mining activity at the Pikeview Quarry. A second, related slope failure occurred on September 13, 2009. The second slope failure was located immediately adjacent to the initial December 2008 failure. The objective of this publication is to discuss the three-dimensional slope stability evaluation. The causal relationships of slope instability are not within the scope of this publication. However, omitting the precursors to slope failure would limit understanding of the nature of the slope stability evaluation. The regional and local geology and the history of slope instability at the Pikeview Quarry aid in understanding these precursors. Two main failure mechanisms were hypothesized during the failure investigation to explain the triggering of the 2008 and 2009 large slope failures at the Pikeview Quarry. Both mechanisms are given equal credence in this publication. Quarry excavation was a key factor in the slope instability for both failure mechanisms. The objective of the three-dimensional model was to evaluate the effects of extraction and backfill at the toe of the slope with respect to slope stability. GEOLOGY Regional and local geology are both important factors in slope instability at the Pikeview Quarry. Geologic structure at the quarry is related to regional mountain building and basin development associated with the Laramide Orogeny and the Rocky Mountains. Lithologies at the Pikeview Quarry are also related to regional trends. Localized geologic features, primarily related to weathering and erosion, have also been major contributing factors to slope instability at the Pikeview Quarry."

Jan 1, 2017

By P Hayes, D Fadhlurrahman

Molten slags, fluxes and salts play key roles in a wide range of the high temperature industrial process applications, including metals production, refining and recycling, metal manufacturing processes, electrochemical metal production cells, batteries, and efficient heat transfer media. Recognising the importance and significance of fundamental scientific knowledge of these systems, the International MOLTEN Conference series was established to provide a forum to bring together leading academic researchers and industrial engineers to present and discuss the latest scientific ideas and findings, and their application in their respective fields. This article presents an analysis of the research carried out in this field over time in terms of the number of journal articles, fields and slag systems studied and geographical origin of the research.

Jun 19, 2024

By J. E. Brantly

In October 1939, a drilling program was commenced on the Atlantic seaboard of Brazil, with three steam rotary rigs of medium capacity. One of these was assigned to the State of Alagbas and the other two to the State of Bahia. During the remaining few months of 1939 and during the year 1940, some eight wells were drilled, two in Alagbas and six in Bahia. Two small producers were found in the latter state. In early 1941 three medium-weight Diesel rigs were added to the equipment, thus permitting the drilling of some 15 wells during the year 1941. The two small producers found in 1940 in the State of Rahia were near the city of Silo Salvador. In 1941 three additional small wells were brought in, in the same area, and a further producer on an isolated structure some 75 km. to the northwest of this production. No commercial production has been found in the State of Alagbas. Approximately 26 wells have been drilled or are drilling, six of which are producers— five in one area and one in another. The program for 1942 calls for the development of the two areas in which wells have been found and also the drilling of several wildcat structures located either by geophysics or surface geology. All production in the area of the several producing wells is somewhat less than 2000 ft. and in the other area about 3800 ft. The area of the several wells is known as the Lobato field, and is practically within the city limits of Sao Salvador. The area 75 km. northwest of the city will be known as the Candeias field.

Jan 1, 1942

By J. E. Brantly

In October 1939, a drilling program was commenced on the Atlantic seaboard of Brazil, with three steam rotary rigs of medium capacity. One of these was assigned to the State of Alagbas and the other two to the State of Bahia. During the remaining few months of 1939 and during the year 1940, some eight wells were drilled, two in Alagbas and six in Bahia. Two small producers were found in the latter state. In early 1941 three medium-weight Diesel rigs were added to the equipment, thus permitting the drilling of some 15 wells during the year 1941. The two small producers found in 1940 in the State of Rahia were near the city of Silo Salvador. In 1941 three additional small wells were brought in, in the same area, and a further producer on an isolated structure some 75 km. to the northwest of this production. No commercial production has been found in the State of Alagbas. Approximately 26 wells have been drilled or are drilling, six of which are producers— five in one area and one in another. The program for 1942 calls for the development of the two areas in which wells have been found and also the drilling of several wildcat structures located either by geophysics or surface geology. All production in the area of the several producing wells is somewhat less than 2000 ft. and in the other area about 3800 ft. The area of the several wells is known as the Lobato field, and is practically within the city limits of Sao Salvador. The area 75 km. northwest of the city will be known as the Candeias field.

Jan 1, 1942

1. New publications International minerals/metals review - 1982. Washington D.C., McGraw-Hill, 1983.720 pp. U.S.$1l7. Mining subsidence engineering, by Helmut Kratzsch. New York, Springer, 1983.580 pp. U.S. $63,20. Papers presented at the 6th International Symposium on Jet Cutting Technology, Guildford, England: April 6-8, 1982, edited by H. S. Step hens and E. B. Davies. Cranfield (England), BHRA Fluid Engineering, 1982. £40. 2. Mintek reports Report M95 Modern applications of polarography and voltammetry to inorganic analysis. Report M96 The mathematical modelling of the reduction behaviour of chromite from the Upper Chromitite Layer of the Bushveld Complex. Report M113 The selective flotation of South African chromite. Conference on copper The International Conference 'Copper 83', to be held in London on 1st and 2nd November, 1983, will provide a valuable forum for all connected with the manufacture and use of copper. Underwater mining The 14th Underwater Mining Institute will be held in Madison, Wisconsin, on 7th and 8th November, 1983. Asian mining The Institution of Mining and Metallurgy, in conjunction with the Chamber of Mines of the Philippines, will hold an international conference, Asian Mining '84, in Manila, Philippines, from 6th to 8th November, 1984. Apcom '84 The Eighteenth International Symposium on the Application of Computers and Mathematics in the Minerals Industries will be held in London in the week 26th to 30th March, 1984. The Symposium is being Jet cutting Another Symposium on the very successful and popular series of international conferences on Jet Cutting Technology is being arranged by BHRA.

Jan 1, 1983

THE LIFE and works of Alexander Agassiz, first president of the Calumet & Hecla Mining Co., were recalled to memory when a monument bearing his statue was unveiled in Agassiz Park, at Calumet, Mich., on Sept. 26, The statue is the work of Paul W. Bartlett, of New York, and was erected by George R. Agassiz, eldest son of Alexander Agassiz. We are indebted to Rodolphe L. Agassiz, now president of the Calumet & Hecla Consolidated, for the accompanying photograph of the statue. The principal address at the unveiling ceremony was delivered by Allen F. Rees, of Houghton, who said, in part: To the world at large Alexander Agassiz was preeminently the man of science. With all his devotion to the industrial life of this district, he found the time to devote to the con-tinuation of his work of scientific research which had been the life work of his fa-ther, Louis Agassiz. Not only did he acquire eminence for his scientific at-tainments and learn-ing, but he was recognized and hon-ored throughout the civilized world for his achievements and accomplishments in the realm of original research. His work in the fields of nat-ural science, in oceanography, in marine zoology, and in other similar lines of research, has added much to our knowledge of the world's mysteries. His life was one of accomplishment also in the industrial world. The union in one life of acknowledged achievement as a scientist and the accomplishment of great results in the prac-tical industrial world is a rare thing, and its possibility has never been exemplified in greater measure than in his life and its results.

Jan 11, 1923

By R. J. Mechin

TOP-SLICING was introduced in the Pachuca district in 1917 by T. C. Baker, at that time mine superintendent, of the Santa Gertrudis mine. There then existed 1200 ft. (365.7 m.) below the surface, lying between the fourteenth and eighteenth levels (a vertical distance of 108 meters) a block of ore having a length of 295 ft. (90 m.), and an average width of 82 ft. (25 m.) and dipping at an angle of 65°. This block lay in the hanging wall of the vein and consisted of highly altered and fractured andesite, cut through with mineralized quartz stringers. On the foot-wall side, 26 ft. (8 m.) of old filling, left by former operators, was of payable grade. Stoping therein was first undertaken by the square-set filling system, but because of the extremely heavy hanging wall and loose dry filling in the foot wall, all square setting had to be accompanied by spiling, which made the operation exceedingly slow and costly. A system of mining was sought that would eliminate the difficulties inherent to the square-set system in heavy ground and that at the same time would effect the desired economies in mining. After several years, top-slicing has met all the conditions most satisfactorily, so that when similar conditions presented themselves in El Bordo mine, this method was adopted with necessary modifications. El Bordo mine is operated by the Santa Gertrudis company, and is situated about two miles north of Pachuca. Because of the diversity of the orebodies, a number of different mining methods are in use, among them top-slicing.

Jan 10, 1925

By William T. Folwell

The Lucky Friday mine east of Mullan, Idaho, is an outstanding example of a property in the Coeur d’Alene district where a small and insignificant- appearing silver-lead-zinc vein at the surface has changed at depth into a large vein of great importance. The Lucky Friday vein has little if any surface expression and above the 1200 level the ore shoots are small and discontinuous. Between the 1200 level and 2450 level, the lowest developed level, the main ore shoot has shown remarkable improvement on each succeeding lower level, and today the mine is one of the major lead-silver producers in the Coeur d'Alene district. History: The Lucky Friday property is on the north side of the South Fork of the Coeur d'Alene River in sections 25, 26 and 35, T. 48 N., R. 5 E., Hunter mining district, Shoshone County, Idaho. This is about one mile east of the town of Mullan, which serves the eastern portion of the Coeur d'Alene district. The southern part of the property is crossed by a branch line of the Northern Pacific Ry. and by U. S. Highway 10. This highway is the principal road crossing the panhandle of Idaho and connects the district with Spokane, Wash., on the west and Missoula, Mont., on the east. The main portal and surface plant of the Lucky Friday mine is at an elevation of 3365 ft, only a short distance above the valley floor and a few hundred feet from U. S. Highway 10, so the mine is readily accessible for year-round operation.

Jan 12, 1958

By L. Bombardieri, H. F. Mills

Iron King mine, producing gold-silver-lead-zinc-ore, is 10 miles east of Prescott, Ariz. At present the 1806 level is being developed. The echelon pat tern of ore deposit continues at depth but is less pronounced, and the orebody is now more or less continuous over 2600 ft of strike length, with widths 5 ft to as high as 26 ft where overlapping of lenses occurs in one section of the mine. Better continuity of ore at depth has encouraged systematic mining and improved plant facilities to offset higher operating costs. With favorable persistence of ore at depth, the three-compartment No. 6 hoisting shaft appeared inadequate to handle increased tonnage from greater depths, and in 1952, a four-compartment steel and concrete shaft was started. This is now at a depth of 1906 ft, and shaft pockets and loading cartridges are being installed on the 1806 level. Ore from the new shaft, hoisted in 5 ½ -ton Jeto bottom dump skips, is dumped into a 500-ton shaft bin, from which it is fed to a 16x30-in. gyratory crusher and conveyed 415 ft through an undersurface concrete gallery to the secondary crusher and conveying system supplying the 900-ton mill. Lead, zinc, and pyrite concentrates are floated, and the flotation tailings are cyanided after desliming. Waste from the new shaft is dumped into a 250-ton surge bin, fed from this bin to a 24-in. conveyor, and discharged into the glory hole above the block cave. The new shaft is served by a double-drum 400-hp hoist used for ore and waste; the No. 6 shaft conveys men and material.

Jul 1, 1956

By H. F. Seifert

THE classification and preparation of non-ferrous scrap metals is a subject of interest to every individual and corporation that employs in its processes of manufacture non-ferrous metals and alloys and accumulates in such manufacture scrap from these materials for disposition in the form of turnings, borings, short ends, punchings, clippings, grindings, washings, etc. All too frequently the disposition of such scrap is left to individuals who have no knowledge of the subject either from a metallurgical or a commercial standpoint, or both. Much money is thus lost which with a little more intelligent effort might be saved, and in this day of fierce competition and small profits such an opportunity cannot be ignored. The Mineral Resources of the United States for the year 1925, the latest issue available (Part 1, page 221), gives the secondary non-ferrous TABLE 1.-Some Secondary Non-ferrous Metals Recovered in the United States for the Year 1924-25 Material Short Tons Value Copper, including that in alloys other than brass.... 250,600 $ 71,170,400 Brass, scrap remelted 242,300 56,270,800 Lead as metal 112,4201 39,477,100 Lead as alloys 112,460 Zinc as metal 61,430 11,359,000 Zinc -in alloys other than brass 13,300 Tin as metal 1 7,950 35,165,400 Tin in alloys 23,000 Antimony as metal 1 } 3;794,000 Antimony in alloys 10,839 Aluminum as metal 17,700 24 Aluminum in alloys 26,300 ,816,000 Nickel as metal 19 1 1,518,000 Nickel in non-ferrous alloys 2,109 Total 882,600 $243,570,700

Jan 1, 1928

By H. F. Seifert

THE classification and preparation of non-ferrous scrap metals is a subject of interest to every individual and corporation that employs in its processes of manufacture non-ferrous metals and alloys and accumulates in such manufacture scrap from these materials for disposition in the form .of turnings, borings, short ends, punchings, clippings, grindings, washings, etc. All too frequently the disposition-of such scrap is left to individuals who have no knowledge of the subject either from a metallurgical or a commercial standpoint, or both. Much money is thus lost which with a little more intelligent effort might be saved, and in this day of fierce competition and small profits such an opportunity cannot be ignored. The Mineral Resources of the United States for the year 1925, the latest issue available (Part 1, page 221), gives the secondary non-ferrous TABLE 1.-Some. Secondary Non-ferrous Metals Recovered in the United States for the -Year 1924-25 Material Short Tons Value Copper, including that in alloys other than brass.... 250,600 8 71,170,400 Brass, scrap remelted : 242,300 56,270,800 Lead as metal : 112,420 39,477,100 Lead as alloys 112,460 Zinc as metal 61,430 11,359,000 Zinc in alloys other than brass 13,300 Tin as metal 7,950 Tin in alloys 23,000, 35,165,400 Antimony as metal 1 3,794,000 Antimony in alloys : 10,839 Aluminum as metal 17,700 24,816,000 Aluminum in alloys 26,300 Nickel as metal 191 1,518,000 Nickel in non-ferrous alloys 2,109 Total l 882,600 $243,570,700

Jan 1, 1928

By C. E. Semler

A multiyear program involving online, in-vessel exposures at Barrick Goldstrike Mines Inc. (BGMI) has provided information and experience about the materials and designs for brickwork linings in pressure oxidation autoclaves. A variety of brick and mortar products was evaluated. Properties before and after exposure were used to document the performance. Some benefits include the development of a new silicate mortar, a better understanding of brick requirements and increased autoclave operating time between maintenance shutdowns. BGMI operates six pressure oxidation autoclaves at its Eureka County, NV gold operation. These autoclave process 15.8 k/ld (17,500 stpd) of gold ore. Figure 1 is a flowsheet of the six autoclave circuits. The gold ore is refractory, in which the gold particles are mineralogically encapsulated on a micro- and submicroscopic level. The autoclaves are 4.4- m- (14-ft-) diam and 26 m (85 ft) long (tip-to-tip). Inside of each is a full brickwork (brick plus mortar) lining that divides the vessel into five compartments. Each compartment has a motor-driven agitator that keeps the slurry suspended and disperses the oxygen to enhance reaction. During autoclave operation, the conditions are steady state at 210° to 232° C (410° to 450° F) and 61 to 62 kPa (420-430 psi). As shown in Fig. 1, there are other accessory vessels (splash and flash towers) in the autoclave circuits that are also brickwork-lined. The linings used to date, other than small test sections, have all been acid-resistant fireclay bricks, bonded with alkali silicate mortar, PbO- based mortar and/or vinyl ester mortar, but mainly alkali silicate mortar.

Jan 1, 1997

By H. R. Peiffer

Recently artin has indicated that the recovery of resistivity at 145°C following elongation of molybdenum at room temperature was the result of the annihilation of vacancies. The activation energy for this process was, according to Martin, 1.26 ev. This energy seems to be a reasonable one for the activation energy for the diffusion of vacancies in molybdenum. However, impurity atoms such as carbon, nitrogen, and oxygen4 have an activation energy for diffusion in molybdenum of the same order of magnitude (i.e., 1.45, 1.15, and 2.09 ev, respectively). Cottrell and Churchman have already correlated the return of impurity atoms to dislocations in cold-worked iron with the return of the upper and lower yield point. According to cottrel16 the diffusion of carbon atoms to dislocations results in the return of the yield point. As the carbon atoms become trapped by dislocations, Bhatia has shown that a decrease in the electrical resistivity is to be expected. Cottrell and Churchman were able to correlate experimentally the decrease in electrical resistivity with the return of the yield point. Since one would expect strain aging to occur in molybdenum, an experiment was performed to determine whether the resistivity recovery at 150°C for molybdenum cold-worked at room temperature can be correlated with the return of an upper and lower yield point. For this experiment 3/16-in. tensile bars of Climax molybdenum, 99.961 pct pure, were used. The specimens were annealed at 1000° C for 1 hr in an argon atmosphere and then were elongated up to 10 pct on a Baldwin-Lima-Hamilton FGT

Jan 1, 1959

By W. Hrynewich

"The Central Canada Potash facility, a division of Noranda Metal Industries Limited, is located 3 kilometres south of the junction of Highways 16 and 2, about 75 kilometres south-east of Saskatoon, Saskatchewan. The site occupies 26~ hectares of land and includes well-equipped machine and electrical _shops, a 325,000-tonne muriate storage and reclaim warehouse, a stores warehouse, processing plant (mill), two mine shafts (one for production, the other for servicing and personnel transport), as well as a two track product loading complex. Access to the site is by road and railway (CN and CP Rail). Suppliers of operating and maintenance use both means of transportation, whereas muriate shipments are entirely by railway.Currently five continuous mining machines - one a Goodman 526 borer and four Marietta 911-A units produce some 10,500 tonnes of ore per operating day. A smaller Voest-Alpine Af.1-100 boom type miner is used for floor cutting which was previously done by a production unit. In order to maintain safe, competent ground conditions only 35 percent of the total ore is extracted. At this rate mine reserves are deemed adequate for about 100 years. The plant has operated since August 1969 and has a current practical annual capacity of 1,270,000 tonnes of muriate. As of June 30, 1981, some 11.9 million tonnes of muriate had been produced from 31.4 million tonnes of ore. Of the total muriate, 6.1 million tonnes was granular, 4.8 million was coarse, and 1.0 million was standard. No standard product has been made since August 1978."

Jan 1, 1982

By E. A. Barrett, L. L. Rethi

Throughout all segments of the United States mining industry, 163 independent contractor employees were fatally injured between 1990 and 1997. Factors that contributed to these injuries were identified after reviewing descriptive information contained in Mine Safety and Health Administration fatality reports for each of the incidents. Thirty-three unique contributing factors were identified and multiple factors were noted for each fatality. Those most frequently discerned were "failure to follow `standard operating procedures"', (35% of the fatalities), "poor positioning of employee" (26% of the fatalities) and "failure to maintain equipment" (23% of the fatalities). Contributing factors were then associated with the accident and job classifications of the victims. Factors having the highest frequencies in the top five accident classifications where most fatalities occurred were as follows: powered haulage - "failure to maintain equipment"; machinery - "poor positioning of employee"; slip/fall of person - "inadequate fall protection" and "failure to wear safety line"; electrical - "equipment contact with power line"; and falling/rolling/sliding rock - "poor positioning of employee. " Among the job classifications in which most fatalities occurred, leading contributing factors were as follows: truck driver - "failure to follow standard operating procedures" and "poor positioning of employee"; laborer/utility man/pumper - "poor positioning of employee"; mechanic/ repairman and welder - "failure to follow standard operating procedures." Recommendations for utilizing contributing factor information as a basis for safety training are proposed. Training programs may be developed that inform independent contractor employees of factors which, in the past, have contributed to fatal injuries in their job classifications. Then, by combining this information with contributing factors identified in "related" accident classifications, a truly focused training intervention that addresses very specific workplace hazards may he developed.

Jan 1, 2002

By J. C. Reed

CINNABAR was discovered in southwestern Arkansas on Little Missouri River in sec. 1, T.7S., R.26W., in April, 1930, and near Antoine Creek in sec. 28, T.6S., R.23W., some 15 miles farther east in May of the same year. It was not, however, until June, 1931, that cinnabar was identified as such in a specimen from the original discovery area sent to W. M. Weigel1 by Walter F. Hintze of Murfreesboro. Almost simultaneously2, in July, 1931, Moritz Norden of Hot Springs identified specimens from the Antoine Creek area as cinnabar. Immediate interest in the district followed the identification of cinnabar and by January, 1932, the district was known to extend as a mineralized belt about one mile wide trending east-northeast from sec. 13, T.7S., R.27W., in Howard County-across central Pike County and into Clark County to sec. 19, T.6S., R.23W., thence extending southeast into sections 33 and 34 of the same township. Since then, cinnabar has been found in sec. 6, T.7S., R.22W., thus giving a total east-west length to the district of approximately 30 miles. Interest focused mainly on the two discovery areas, with the result that mining development has progressed most rapidly in those localities. In the Antoine Creek area the Arkansas Quicksilver Co. has done con-siderable exploration work and has retorted the high-grade ore so .obtained. In the Little Missouri area the Southwestern Quicksilver Co. has had a 12-ton rotary furnace in more or less continuous operation since April, 1932, and has been the largest producer in the district.

Jan 1, 1935

Reduce well construction and operation costs associated with in situ leach mining while increasing mineral recovery. Approach To accommodate the size of centrifugal pumps presently in use, in situ leaching production wells are typically drilled to 6 inches in diameter, while monitor wells are drilled to measure 4 inches in diameter. However, in order to reduce the cost of drilling these larger diameter wells and to increase recovery, the Bureau has developed jet pumps which have smaller diameters than centrifugal pumps of the same capacity. This allows both production and monitor wells to be drilled smaller. Bureau estimates indicate that the cost of drilling a 3-inch-diameter production well at in situ leaching operations would be about 35 percent less than the cost of a 6-inch well. Similarly, the cost of drilling a 2-inch-diameter monitor well would be about 26 percent less than the cost of a 4-inch well. Such significant savings in the cost of drilling these wells would effect a substantial reduction in total capital cost. Use of the new jet pumps can also increase the percentage of recovery because less costly wells allow closer well spacings, improving the distribution of the leach solution. How the System Works After the borehole is cased, the new small-diameter jet pump, along with piping and accessories, is installed and connected to a centrifugal pumping unit on the surface. High-pressure water from the surface pump is forced through a nozzle into the venturi of the jet type pump injector. This jet action lifts the leach and mineral-bearing solution to the surface.

Jan 1, 1984

By Wm. C. Madge, H. P. Allen

The chloridizing mill of the Standard Reduction Co. is located about 75 miles south of Salt Lake City on the Tintic branch of the Denver & Rio Grande Western R. R. and 12 miles from the Tintic Standard mine. The daily capacity is 200 toss of a siliceous, low-grade, silver-lead ore from this property. It has operated continuously since it was started in January, 1921. The process consists essentially of a chloridizing roast followed by a percolating leach with a nearly saturated solution of common salt, acidified with sulfuric acid, the precipitation of silver on sponge copper and of copper and lead on tin-plate cuttings. The precipitates are shipped to a smelter. Some of the general ideas involved are said to have been used by Augustin in England, in 1840. A number of textbooks treat of the subject, especially the chloridizing roast followed by a leach with sodium hyposulfite or amalgamation. The process was revived in this district by Theo. P. Holt, N. C. Christensen, the Bureau of Mines, and others. Nature of Ore Treated The average assay of the ore treated during 1924 is as follows: Gold, ounces per ton...................................... 0.025 Silver, ounces per ton..................................... 18.26 Copper, per cent......................................... 0.30 Lead, per cent........................................... 5.00 Silica, per cent........................................... 65.00 Iron, per cent............................................ 10.00 Lime, per cent........................................... 0.70 Sulfur, per cent.......................................... 3.00 Arsenic, per cent......................................... 0.70 The silver is finely disseminated and occurs as native, combined as a sulfide and, to a very small extent, as the chloride. The lead may be present as carbonate, sulfide, or sulfate.

Jan 1, 1926