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By CDC CDC

In 2004, a total of 251 metal mining operations reported employment to the Mine Safety and Health Administration (MSHA). Metal mines were the smallest mining commodity sector, comprising 1.7% of all mining operations. • Gold mines

Sep 1, 2007

By P. A. Riveros, J. Binvignat, V. M. McNamara, D. Koren

The recovery of cyanide from a gold mill solution containing high levels of copper (400 mg/L to 900 mg/L) using the AVR process was evaluated. It was determined that acidification to pH 2 to 3 provides a suitable balance between HCN generation, copper precipitation and acid consumption. A short pilot plant campaign showed that ~75% of the feed WAD cyanide was recovered while the remainder precipitated along with copper upon acidification. The acid consumption averaged 3.5 g H2SO4 per litre of solution. The copper precipitate, consisting mostly of CuCN and CuSCN, was readily separated from the solution by gravity. The volatilization of HCN in countercurrent packed columns averaged 98.7% efficiency. Reabsorption of HCN was practically 100% in NaOH solutions and slightly lower in a lime slurry. Basic volatilizer design parameters applicable to a large-scale operation were determined, including the Henry’s Law constant and the mass transfer coefficient of HCN gas.

Jan 1, 1998

By C. Cutts, K. Wheatley

The Dragon Lake Zone (uranium prospect) comprises a N160º trending vein that is approximately 110 m long, up to 5 m wide and from 1 to 40 m high. The zone is mostly within altered sandstone of the Fair Point Formation, the basal unit of the Paleoproterozoic Athabasca Group, but it also extends downward (up to 3.5 m) into basement rocks that occupy the northerly trending Maybelle River Shear Zone (MRSZ). This subvertical shear zone separates graphitic paragneiss and weakly deformed granitoid rocks to the east from non-graphitic paragneiss and foliated granitoid rocks to the west. The Dragon Lake Zone cuts across both the MRSZ and N060º-N070º-trending cross-faults that offset the shear zone but not the mineralized vein, which contains values up to 54.5% U over 50 cm core length. Strong chloritization occurs in graphitic paragneiss and sandstone adjacent to mineralization. Silica was depleted from the basement rocks and redeposited at the borders of the 5-15-m-wide alteration zone, as well as within overlying sandstone of the Manitou Falls Formation. There are minimal alteration effects in the overlying Lazenby Lake Formation. Geochemistry shows that the alteration zone in the Fair Point Formation is highly anomalous in metals, most notably in Ni, As, U, Pb, Co, and B. Clay within this zone is illitic and Fe-rich chlorite is also present. Brittle deformation is not as widespread or as well developed in the Fair Point Formation as it is in the overlying Manitou Falls Formation, which is extensively brecciated and contains some anomalous metal values.

Jan 1, 2013

By A. R. Kirchner

This paper describing the practice at the concentrator of the Minas de Matahambre, S. A., is one of a series being; prepared by the Bureau f Mines on milling methods and costs. The Minas de Matahambre, S. A., concentrator treats the production of the Matahambre mine and has a capacity of 1,300 tons of copper ore per day by selective flotation. During the year 1930 the heads averaged 4.55 per cent copper, the concentrates 29.20 per cent copper and the recovery was 95.96 per cent.

Jan 1, 1931

By Kenneth N. Han

Thermodynamic and kinetic aspects of nickel and cobalt leaching from metals. minerals and ores in various media have been reviewed and discussed in this paper. A kinetic model developed to delineate the leaching mechanisms for these metals has been discussed in view of experimental observations. The current review also includes the dissolution behavior of nickel and cobalt from various minerals such as oxides, sulrides. ocean floor manganese nodules, and laterites. A particular emphasis has been extended to similarities and differences of the dissolution behavior of these two metals in various media. The leaching of nickel as well as cobalt metal in acidic solutions and arnmoniacal solutions exhibits in most part mass transfer controlling. although at some pH's, chemical controlling or mixed controlling mechanisms seem to prevail. The leaching of nickel and cobalt from oxides in acids and ammoniacal solutions. on the other hand, can be described best by chemical controlling mechanisms.

Jan 1, 1993

By J. J. Shields

The Bureau of Mines observed two different types of longwall mining; the advancing longwall method and the retreating longwall method at seven bituminous coal mines located in five of the coal producing states. In two mines using the advancing face method, the coal faces were abandoned because of roof failures and poor production. In the other five mines using the retreating method, roof control was good as was production. The success of longwall mining depends on good roof control and good production. The use of self-advancing hydraulic roof supports, such as Westfalia, Dowty, and Wanheim props along with Westfalia coal planers and the Anderton and Eickhoff shearer-loaders have been a factor in recent successes.

Jan 1, 1967

By R. J. Kuczynski

The U.S. Bureau of Mines operated a 2,000-g (4.4-lb) batch process development unit for recovering platinum-group metals (PGM) from automobile catalysts. Virgin monolith, used pellet, and used monolith catalyst samples were tested. Leaching twice with 1-pct sodium cyanide (NaCN) solution at 1600 C for 1 h dissolved more than 95 pct of the PGM from virgin catalysts and more than 90 pct from used pellet catalysts. More than 85 pct of the PGM was dissolved from used monolith catalysts when a third autoclave step was added. Solid PGM concentrates containing more than 99.8 pct of the dissolved PGM and analyzing greater than 70 pct PGM were recovered by heating the pregnant leach solutions from virgin catalysts to 2500 C and used catalyst to 2750 C for 1 h. The solution after heating contained less than 0.2 ppm. total cyanide. The virgin residues passed the EPA Extraction Procedure Toxicity Test (EP Tox Test), the EPA Toxicity Characteristic Leaching Procedure (TCLP), and the California Waste Extraction Test (WET) for all elements except Ba. Adding sodium sulfate (Na2S04) to the virgin leach residues reduced the amount of Ba dissolved to an acceptable level. The used leach residues passed the EP Tox Test for all elements but failed the WET and TCLP for Pb.

Jan 1, 2010

By P. A. Bloom

Bureau of Mines research was conducted to develop effective separation methods that might be used in exploiting substantial tonnages of complex barite-fluorspar ores in Arizona. The exploitable reserves now may be increased as recent batch and continuous flotation tests demonstrated that a complex barite?-fluorspar ore from the Red Chief deposit, Yuma County, Ariz., could be selectively treated to concurrently produce (1) fluorspar and (2) a barite byproduct of marketable grade. The sample contained 24.8 percent CaF2 and 24.3 percent BaS04. Processing comprised production of a fluorspar product containing 97 percent CaF2 with an 82 percent recovery, using a sodium fluoride-lignin sulfonate-fatty acid reagent combination. Concurrent retreatment of the fluorspar tailing, using sodium cetyl sulfate as a collector, yielded a barite product of 94 percent BaS04 grade with a 71-percent recovery. The products met specifications for acid-grade fluorspar and drilling mud-type barite.

Jan 1, 1963

By Stephen W. Paff

The EPA has estimated that there are over 3,000 sites across the United States contaminated with lead. Techniques to remediate these sites include standard stabilization/disposal technologies, reclamation of lead using secondary lead smelters, soil washing, and biological removal technologies. In this paper, the current technologies used for lead remediation will be reviewed. Factors affecting the use of each technology, such as range of applicable concentrations, soil types, interferences from other contaminants, economics, and current technology status will be assessed. The paper will also focus on the results of a recent study completed by the Center for Hazardous Materials Research (CHMR), in conjunction with a major lead smelter, which demonstrates that secondary lead smelters may be used economically to reclaim lead from a wide range of lead-containing materials frequently found at Superfund sites. Such materials include battery case materials, lead dross, and debris containing between 3 and 70% lead. The results of development work completed by CHMR on the Acid Extraction Treatment System (AETS), which has been demonstrated to extract Lead from soils containing up to 30,000 mg/kg lead, will also be presented. The use of these technologies will be compared with other options for the remediation of sites.

Jan 1, 1994

By Joan T. May

The Federal Bureau of Mines investigated the potential for recovering aluminum from copper-dump leach liquors by use of single-contact ion-exchange technology. A strongly acidic ion-exchange resin was used to extract aluminum from a typical dump leach liquor and from synthetic leach liquors. Aluminum was stripped from resin with a HS04 or NaCl solution. Bench-scale experiments indicate that a single-contact ion exchange is technically feasible, but that the process is limited by the relatively low loading capacity of the resin and the excessive amount of stripping agent required. A further limitation is that significant amounts of magnesium and iron are loaded and stripped along with the aluminum.

Jan 1, 1976

By W. J. Fene

The lowest number of fatalities from coal-mine explosions in the United States in any year since records have been kept was the total of 8 in 1949 and again in 1950. Even incomplete records as far back as 1870 reveal a larger annual loss of life from explosions. From 1890 to 1948 the lowest annual loss was 32 in 1946. A smaller total of 15 fatalities was reported in 1952. Figure 1 shows the total yearly loss of life from explosions in all coal mines since 1880. Those in anthracite mines alone are shown by the shaded area. The erratic variation of the chart line shows the difficulties that have confronted the industry in the struggle to control and eliminate mine explosions. Potential hazards have existed in marry mines without realization that only a small change in conditions could initiate a disaster. Many disasters causing great loss of life occurred in mines that had been regularly operated without incident for long periods. Although the number of coal-mine explosions causing great lose of life has been kept down in recent years, the exceptions still make the record anything but satis¬factory. There have been almost no widespread explosions for several years, but in a few instances many lives were lost from afterdamp. Although the violence and spread of mine explosions may be controlled, the loss of life may be heavy if many of the men happen to be in the path of the smoke and gases. For these reasons, the strictest controls must be maintained to eliminate all factors that might combine to cause even a small ignition of gas or dust.

Jan 1, 1953

By H Ishikawa, H Zhou, M Spagnolo, R Halomoan, S Palaniandy

The Karara Mine concentrator commenced operation in November 2012 to produce high-grade magnetite concentrate. The circuit consists of three stages of comminution plus magnetic separation at each stage for early gangue rejection. High-Pressure Grinding Rolls (HPGRs) are used for fine crushing, followed by ball mills and TowerMills in secondary and fine grinding duties respectively. In recent times, the plant throughput rate has had to exceed design by 18% to maintain the targeted concentrate productivity. Meanwhile, the ore hardness has increased by 25% to 15 kWh/t, leading to changes in the circuit operation and design. These changes led to coarser and harder feed to the TowerMill circuit that affects the subsequent separation processes. Nippon Eirich (the TowerMill manufacturer) has partnered with Karara Mining Limited (Karara) to optimise the TowerMill circuit operation to achieve a circuit product with an 80% passing (P80) of 35 µm. Several activities, including a TowerMill circuit audit and performance evaluation, multi-component analysis, modelling and simulation, were carried out as part of the optimisation exercise. The circuit audit results revealed that the TowerMill circuit feed size F80 had increased and ranged from 67–75 µm. The circuit product P80 ranged between 42–55 µm. The average circuit specific energy was 3.4 kWh/t. Moreover, the differences in density between magnetite and gangue minerals had affected the hydrocyclone performance where the efficiency curve exhibits coarse end deflection indicating that low-density coarse material was bypassing to the overflow stream. A multi-component analysis was carried out to further investigate the coarse end deflection of the hydrocyclone efficiency curve. The analysis showed that the magnetite and gangue minerals had different cut sizes of 32 and 64 µm respectively. Furthermore, 33% of the magnetite (below 35 µm) was being recycled back to the mill due to the density effect. Based on these findings, several recommendations for process improvement were identified and implemented including:• converting to a bottom feeding configuration to improve the grinding efficiency in the mill• additional grinding power in the fine grinding duty to compensate for the increase in plant throughput and ore hardness• improved classification efficiency by converting to smaller size hydrocyclones. Simulation studies carried out to evaluate the impact of these implementations had indicated that a P80 close to 35 µm with a steeper size distribution could be achieved by using the bottom feed configuration with additional grinding power. The TowerMill circuit was converted to bottom feed configuration and the performance was evaluated. The operating work index, size specific energy and circulating load were 30% lower than the top feed configuration, indicating that the bottom feed configuration had a higher grinding efficiency. This paper discusses the outcome of the circuit audit, multicomponent analysis, circuit simulations, improvement strategies and quantification of the improvements. CITATION:Palaniandy, S, Spagnolo, M, Halomoan, R, Zhou, H and Ishikawa, H, 2017. Fine grinding circuit process improvement at the Karara mine concentrator, in Proceedings MetPlant 2017, pp 101–120 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 11, 2017

By S. M. Shelton

The widespread occurrence of domestic manganese deposits and the shortage of ferromanganese-grade ore have been sources of much speculation and investigative effort for many years. The present emergency has intensified the search by the Bureau of Mines for methods of producing ferromanganese-grade concentrates4/ from low-grade ores.

Jan 1, 1941

By D. M. Dabbs

A static dew point technique has been used to evaluate the solubility of arsenic in ?slag and its dependency on P02 at temperatures of 1458 and 1523K. The ferrous-ferric ion ratio of the slags ranged from 3.9 to 23.8. These values correspond to partial pressures of 02 ranging from 10-8 to 10-12 atm. The solubility of arsenic in slag was found to be independent of? P02? The data indicate that elemental arsenic exists in silicate ?slags. This result was further substantiated by mass .spectrometric analysis of doped slag specimens.

Jan 1, 1983

By R. L. Bullock

For the past 30 years there has been a gradual evolution of mechanical excavating systems in underground hard rock mining applications. This paper traces many of the tests of various tools and methods to break hard rock, up to the present. The tools include impact hammers, boring machines, disc on boom mining machines, disc on revolving wheels and drums, picks and drag bits on revolving hubs, rock splitters, slot cutting systems, and with customized explosives/powder mini-blasting. While the progress has been slow, successes are being achieved in hard rock and more opportunities exist today than ever before.

Jan 1, 1995

By K Hortin

Kidd Creek mine in north western Ontario is developing phase 1 of the deep mine project for mining between 2100 m and 3100 m below surface. Heat problems were experienced during the 2003 summer in working places about 2300 m below surface. At the time the mine had a æcold stopeÆ for cooling the air supplied to the mine below 1500 m from surface. The æcold stopeÆ is where during winter, ice is created in both the open pit and its connecting airways to the mine and used to cool air in summer. The operation and limitations of the existing cold stope were evaluated and led to the requirement for additional mechanical cooling to be available for the summer of 2004. The first stage of a surface refrigeration plant providing 7.5 MWR of cooling was approved, the compressor set was ordered in early January 2004 and the plant commissioned six months later in early July 2004. Based on the current modifications to the mining plan, further plant expansions are required in 2006 and 2009 leading to a total of 19 MWR of mechanical refrigeration and 8.5 MWR equivalent from the extended cold stope. The refrigeration system is described with emphasis on the specific adaptations necessary to suit Canadian conditions. Additional investigations were; using the refrigeration compressors in winter for heating and, extending the performance of either cold stopes or alternative ice storage systems. The winter use of refrigeration involve removing heat from the mine exhaust air to provide a cooling load and to use the hot water in the condensing circuit to heat the intake air and reduce reliance on mine air heating with natural gas. This paper follows on from an earlier one presented at the Seventh International Mine Ventilation Congress where the background and planning of the mine ventilation and cooling requirements were described for extending the mine at depth to 3100 m.

Jan 1, 2005

By I Ametov, S Harmer, R Alford

A process that allows selective flotation separation of low Cu/S ratio minerals (chalcopyrite and pyrite) from high Cu/S ratio minerals (bornite and chalcocite) from a mixed copper mineral concentrate under controlled oxidative-reductive potential conditions has been developed. The process has been extensively tested on samples with varying mineralogy using laboratory batch flotation tests and mini pilot plant trials.In this process, the mixed final copper mineral concentrate is purged with nitrogen, and then treated with sodium dithionite to achieve a slurry Eh in the -200 to -100 mV standard hydrogen electrode (SHE) range. Flotation was then carried out using nitrogen gas. As a result, a low Cu/S ratio concentrate (<1.3) and a high Cu/S ratio (>1.6) tailing stream were produced. QEMSCAN analysis of the flotation products showed that more than 85 per cent of the chalcopyrite and 95 per cent of the pyrite reported to the froth concentrate. Chalcocite and bornite were almost evenly distributed between the concentrate and tailing streams.Surface analysis studies, focused on the mechanism of separation, showed that at a negative redox potential xanthate and possibly dixanthogen are the dominant hydrophobic species on the surface of chalcopyrite and pyrite. As a result, the flotation of these minerals remained unaffected. In contrast, a much lower concentration of xanthate species on the surface of chalcocite and bornite particles was observed. Therefore, it is likely that at low Eh the copper xanthate complex desorbs from the chalcocite and bornite surfaces, causing a decrease in surface hydrophobicity and the diminished floatability of chalcocite and bornite.CITATION:Ametov, I, Harmer, S, Grano, S and Alford, R, 2014. Selective flotation of chalcopyrite and pyrite from a mixed copper mineral concentrate under controlled redox potential conditions, in Proceedings 12th AusIMM Mill Operators’ Conference 2014 , pp 131–140 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 1, 2014

By Alexander Sutulov

Si bien América Latina posee una riqueza mineral extraordinaria y es un importante proveedor de materias primas en el mercado internacional, no hizo un buen uso de sus recursos minerales. En ese sentido, el presente texto señala el análisis económico y tecnógico de Latinoamérica frente a la demandas de tres potencias industriales (EE.UU., Europa Occidental y Japón) que, al mismo tiempo son los principales clientes. Para mantener su ritmo de desarrollo industrial, Latinoamérica necesita divisas provenientes de la exportación de materias primas, donde la conservación de los mercados y el aprovechamiento de los mismos. Asimismo, es necesario un mayor grado de elaboración y purificación de materias primas y que la producción de productos minerales sea de alta calidad a precios competitivos.

Sep 1, 1969

By Kendall Y. Onstott

The paper presents the results of a plant test using WEMCO 1 + 1 enclosed flotation machines for inert gas (nitrogen) flotation of by-product molybdenite from copper sulfide concentrate. Copper depressant consumption in the rougher flotation stage was reduced by 68% as reagent consuming oxygen was removed from the flotation air. Unlike other nitrogen flotation systems used in the industry, nitrogen is recovered above the flotation cells and from froth in tails and concentrate streams and recycled, resulting in minimal nitrogen makeup requirement.

Jan 1, 1984

By C. Thomas Hillman

This Bureau of Mines report describes an investigation of factors influencing economic viability of a proposed system to mine and process manganese nodules. The system consists of hydraulic dredging and ammonia leach processing designed to recover three metals: nickel, copper, and cobalt. A ferromanganese recovery plant is a considered option. Annual capacity is 3 million dry metric tons (t) nodules. Aftertax rates of return (ROR's) of only 7.38 and 6.63 pct are predicted for three-and four-metal base scenarios, respectively. Sensitivity analyses indicate that variations in commodity prices, metal recoveries, and deposit grades produce similar incremental changes in ROR. Estimated cumulative effects of price variations are greatest. While three-metal operations generally yield higher predicted returns, potential increases in manganese price and process recovery could make four-metal operations most profitable. Maximum variations in both capital costs and three-metal operating costs result in ROR changes of about 25 pct. In contrast, four-metal ROR's exhibit variations to 70 pct. Even so only a best case analysis, utilizing favorable variations in all categories tested, generated ROR's approaching a level thought necessary to trigger company interest. Consequently, it is concluded that nodule mining will not take place in the foreseeable future without significant financial incentives.

Jan 1, 1985