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From 2009 to 2012, Aker Wirth, in cooperation with the BGR (German Federal Institute for Geosciences and Natural Resources), developed a concept for the deep sea mining of manganese nodules, which it also examined by means of a profitability analysis. The study was undertaken for the German Federal Ministry of Economics and Technology. The increasing scarcity of resources, coupled with the continuous rise in resource prices, drive the search for new raw material deposits. As a result, the deep sea is coming increasingly under the spotlight. At depths of more than 1,000 m (3,280 ft), large deposits of ores and precious and high-tech metals, such as manganese, cobalt, nickel, copper and gold, along with rare earths (which are important for the high-tech industry), can be found. The extreme deep sea conditions ? enormous water pressure, ice-cold temperatures and complete darkness ? present huge financial and technical challenges to the mining industry when extracting these materials. Aker Wirth has recognized the potential of this important future market early on and advances the development of relevant products.

Jan 1, 2013

By I. Demers, A. Blier, M. Mbonimpa, M. Benzaazoua, B. Bussière

The Doyon Mine in Quebec, Canada, evaluates the possibility of desulfurizing its tailings to produce material to be used as cover for the acid-generating tailings disposal site. Laboratory tests showed that a single-layer cover made of desulfurized tailings placed over reactive tailings can prevent the generation of acid mine drainage. Modeling with the software Vadose/W was used to optimize the design parameters, namely, cover thickness, water table position and residual sulfide content of desulfurized tailings following laboratory work. It was found that the optimal configuration includes a 1-m (3.3-ft) desulfurized tailings cover containing 0.8% S, with the water table kept at the interface between the reactive tailings and the cover. To maintain the cover performance to reduce oxygen flux toward acid-generating tailings even in the event of a long dry period, a sand layer is suggested to protect the cover from excessive evaporation. It is possible to reach the environmental objective for oxygen flux chosen for the Doyon Mine (10 mol/ m2/year) with the protective sand layer, even in extremely dry conditions.

Jan 1, 2009

By Gary L. Simmons

Over the past several years, Newmont Gold Company (previously Santa Fe Pacific Gold Corporation) developed a new technology for the flotation of refractory auriferous sulfide minerals which is referred to as the N2TEC flotation process. Starting in April 1997, the first commercial flotation plant utilizing N2TEC technology was successfully commissioned at the Lone Tree Mine near Valmy, Nevada. The Lone Tree flotation plant was designed to process 4,085 mt/d of ore producing 494 mt/d of sulfide concentrate. A flotation tails leach CIP circuit was added to recover cyanide-soluble gold from the flotation tails. A portion of the flotation concentrate is blended with whole ore feed to the Lone Tree autoclave, up to the limit imposed by the current oxygen plant capacity. The remainder of the concentrate is shipped to either the Twin Creeks autoclaves or the Carlin roaster for subsequent oxidation and gold extraction. This paper discusses the results achieved in the commercial flotation plant compared to pilot plant testing and engineering design flotation modeling. Capital and operating cost information are also presented.

Jan 1, 1999

By M. Sadegh Safarzadeh, Erich U. Petersen, Jan D. Miller

"An acid bake-leach process has been identified and applied to an enargite concentrate containing ~67% enargite, ~27% pyrite (FeS2), ~3% chalcopyrite (CuFeS2), ~6% sphalerite (ZnS) and <1% galena (PbS). Sulfuric acid baking of this concentrate resulted in the transformation of the concentrate to S8, As2O3, HFe(SO4)2•4H2O, PbSO4 and Cu0.47Fe0.53SO4•H2O, all of which (except elemental sulfur and PbSO4) dissolved during the water leaching step. More than 87% Cu and 64% As were leached when the concentrate was baked at 200°C over 7 hours with a sulfuric acid-toconcentrate weight ratio of 1.6. Less than 1% As was lost to the gas phase. Upon water leaching, copper and arsenic were released to the solution at a concentration ratio of about 3:1. While enargite is very reactive during the sulfuric acid baking reaction, other minerals present in the concentrate such as pyrite, galena and sphalerite may compete to consume sulfuric acid and be converted into their corresponding sulfates at different concentrations. The purpose of this paper is to present our examination of the effects of sulfuric acid dosage on the extractions of Cu, Fe, and As from an enargite concentrate. In this regard, the concentrate, baked concentrate, and the leach residues are characterized and a conceptual process flowsheet is described for the acid bake-leach process for the treatment of enargite concentrates.IntroductionThe occurrence of enargite (Cu3AsS4) in copper ores and concentrates and the associated high arsenic values in such resources have resulted in a considerable decrease in the demand for such concentrates because they cannot be economically processed using conventional technologies such as smelting and atmospheric leaching (Mihajlovic et al., 2011). The exploitation of such problematic deposits through competitive treatment strategies will be required in the near future in order to satisfy increasing pressure from the copper market. It is expected that the average arsenic grade of copper concentrates will increase from 0.17% in 2008 to 0.22% by 2020 (Mayhew et al., 2011).The acid bake-leach process was identified and selected for further investigation at the University of Utah as a possible process alternative for the treatment of enargite concentrates. In this case, adequate amounts of concentrated sulfuric acid are mixed with the concentrate and heated to the temperature range 150-300°C. Subsequently, the baked material is leached with water/weak acid and the acid bake-leach process has some advantages over conventional sulfuric acid leaching (Prater et al., 1970). During water leaching, metal sulfates are released in solution, after which they can be extracted through well-known hydrometallurgical techniques. While the majority of the work has been done on oxide minerals, there is a limited record of sulfuric acid baking of sulfides."

Jan 1, 2015

By William L. Rose

Production scheduling is an integral part of intermediate- and long-range open-pit mine planning, affecting equipment selection, manpower requirements and project economics. The development of mining phases, or pushbacks, is discussed in conjunction with generating the best spatial extraction sequence. An approach to scheduling production from these mining phases is then described. Using computers and a production scheduling algorithm, the impact of cutoff grade and advanced stripping policies can be evaluated through sensitivity studies to maximize the return on project investments.

Jan 1, 1985

By R. D. H. Bedd

GEOLOGICAL NOTES The area under discussion is situated approximately 150 m north of Loraine No. 3 shaft at ± 1500 m below surface. The block being mined extends from about halfway between 50 and 52 levels to just below 48 level (see Fig. 1). The EB reefs form the lower portion of the EB zone of the Elsburg series and in the 81 line area the various conglomerate bands show the best development. Up to 18 separate reef bands are developed and the distance from the bottom conglomerate band to the top is ± 26 m. The thickness of the quartzite which forms the middling between the various reef bands varies from 0.1 to 2 m. The strike is roughly north-¬south. The reef bands are payable individually. However, owing to the steepness of the reefs and their close prox¬imity, conventional mining would prove very difficult. The nonpayable reef bands all carry varying amounts of gold and the whole area is a massive payable reef body approximately 26 m wide and 60 m high at 300 to 400 m on strike. The major structure of the area consists of a north¬-south trending syncline. The western flank of the syncline has a steep easterly dip, in places approaching the vertical. This flank cuts out against the overlying rocks of the EA zone. The latter forms a noncon¬formity with the underlying EB zone. The eastern flank of the syncline dips to the west at an average dip of 0.17 rad (10°). The 0.1 rad (6°) north-plunging syncline was sub¬jected to severe faulting. The most important are the Nos. 4 and 10 faults, both of which have a roughly north-south strike. The No. 4 fault dips to the west at an angle of 1.04 rad (60°) with a downthrow of approximately 150 m to the west. The dip of the No. 10 fault is 0.69 to 0.81 rad (40° to 50°) west, with the western block having moved 150 m updip relative to the eastern block. The EB reefs are being mined by the sublevel stoping method down from the sub-outcrop position to the cutoff against the No. 4 fault. On the downthrow side of the No. 10 fault, that is just above the 54 level, two reef bands are payable and will be mined conven¬tionally. ROCK MECHANICS From the section in Fig. 1, it can be seen that the area under consideration is surrounded by stoped-out areas. This will naturally change the stress distribution extensively. The only way to calculate the stress field for such a geometry is to use the finite element method. It was established that this method worked for the present geometry and so the method was applied to predict the stress behavior of the final geometry. From the results, it appeared that the effect of the old stopes was to destress the area. There are, however, some areas-such as the 50 and 48 north footwall haulages-which will require continuous attention. In these two footwall haulages, deterioration can take place due to tensile stress which

Jan 1, 1982

By Kenneth V. Luza

Underclays are associated with coals found in eastern Oklahoma. These coals are of bituminous rank and are in beds of Middle and Late Pennsylvanian age. They occur in an area of about 8,000 mi2, within the southern part of the Western Interior Coal Region. The rocks of the area consist of a thick series of sandstones, shales, underclays, coals, and limestones. There are more than 40 beds of bituminous coal in the state, but only 12 of these have been mined over large areas. The 12 are, from oldest to youngest: the lower Hartshorne, upper Hartshorne, McAlester (Stigler), upper McAlester, Cavanal, Rowe, Secor, Weir-Pittsburg, Mineral, Croweburg, Iron Post, and Dawson coals. None of the underclay associated with these coal beds is known to have been exploited commercially. Nine samples of underclay from beneath the Croweburg coal were collected over a wide area in the eastern Oklahoma coal field for evaluation. The underclays are usually shades of gray with brown or orange iron-oxide staining. Although soft and plastic in some places, they are generally hard and slickensided, and contain abundant carbonized plant fragments. Bulk chemical analyses, clay mineral identification, and ceramic tests were performed on each underclay sample. The dominant clay minerals are illite and kaolinite with some mixed-layer clays. Silica (Si02) ranges from 45.96% to 59.03% and alumina (Al2O3) varies from 14.98% to 23.60%. The U.S. Bureau of Mines Tuscaloosa Re- search Center conducted the ceramic evaluations. Samples were slow fired from 1,000°C to 1,250°C in 50°C intervals. Bulk density, color, percent linear shrinkage, and percent absorption were determined for each slow fire test. All Croweburg underclay samples are best suited for building brick.

Jan 1, 1999

By M. J. Blattman

The problem of measuring the amount of rock removed during a given time interval is faced by most milling operations. Many methods have been developed with varying degrees of success, dependent upon the mining method and the availability of usable data. The Rosebud Mine has been in production for nearly two years, employing several techniques to estimate monthly production from underground production stopes. The use of three-dimensional solids generated from survey data has greatly improved the reliability and confidence of monthly production reports. The authors will summarize the methodology currently being utilized at Rosebud.

Jan 1, 1999

By A. R. Hollbach

This paper presents a succinct overview of the Canadian coal situation. The topics treated specifically are: the rates of growth of coal supply and demand; the relationship between the coal and electricity generation industries which form its dominant market; the unique impact of nuclear generation on coal demand in Canada; and finally, a view of the developing technologies which will create opportunities for growth in the coal industry of the future. Resources The most important element of coal supply is the resource. The disposition of Canada&apos;s coal resources has a marked effect on their utilization, since industry in Canada has not generally developed around coal-fields. The distance from the major industrial centres of Ontario and Quebec to the major region of coal supply in Alberta and British Columbia has crested an economic barrier to the expansion of the use of domestic coal.

Jan 1, 1985

By F. Varley, J. Whyatt

A variety of dynamic failure cases with regional impact were described at a bump symposium held in 1958. These types of events, while rare, are of particular interest because their ability to impact a large area has disaster potential. These cases can be grouped into two broad classes of events by mechanism. These are (1) a slip along steeply dipping faults and (2) the fracturing of strong strata above or below the coal seam. Both failure modes produce dynamic or “shock” loads on the perimeter (roof, rib and floor) of mine openings. Special consideration should be given to these failure modes in the planning of deep coal mines, since their occurrence is not within the professional experience of many contemporary workers. In addition, their potential is not evaluated by many of the analysis tools commonly used to evaluate hazards in coal mine plans.

Jan 1, 2009

By T. M. Gurr

Large quantities of phosphate rock are mined and processed in Central Florida (Figure 1). The phosphate rock from the mines is further processed in "chemical plants" to produce phosphoric acid (Figure 2). A by-product of the processing&apos; of the phosphate rock to produce fertilizer chemicals is an impure form of gypsum referred to as phosphogypsum. For each ton of phosphate rock processed, approximately 1.5 tons of phosphogypsum is produced (Figure 3). The typical method to dispose of this by-product gypsum is to stack it in large piles, locally referred to as gypsum stacks or gypsum fields (Figure 4). These gypsum stacks have been the focus of many studies in recent years in an attempt to identify the potential for ground water and/or air pollution associated with the stacks. This paper attempts to discuss some of the ground water impacts and current attempts to minimize these impacts.

Jan 1, 1990

By Betty L. Gibbs

A clear and accurate knowledge of the status of ventilation in an underground mine is essential to continuing safe operation. In a small mine with a few working faces, the problem is simple and can easily be solved by choosing the appropriate fan. In larger, more complex mines the problem of supplying the working faces with fresh air is a problem beyond the scope of &apos;finger in the wind&apos; analysis. In today&apos;s climate of stiffer government regulation and mining company concern for the safety of workers, computer programs which analyze ventilation networks are helping mining companies meet the standards. The development of computer programs for ventilation network analysis is summarized. Early programs were developed at universities or government agencies and required large expensive computers. As computers have become smaller and less expensive, the development or revision of programs for micro computers has become more available. Prices have lowered to the point of affordability even for medium and small companies. A list of ventilation network analysis programs is provided along with a summary of capabilities, costs, and hardware requirements for each program.

Jan 1, 1987

By Derek. C. Arnold

In order to meet increasing demands for water supply in the next millennium, the Government of the Hong Kong Special Administrative Region have identified the need for a major new water treatment and transfer scheme. The project now under construction will comprise a 1.2 km long raw water aqueduct, a major new 0.25million cubic metres per day water treatment works (with space for upgrading to 1.2Mm³/d), a 12.1 km long treated water aqueduct and a primary service reservoir. In order to meet increasing demands for water supply in the next millennium, the Government of the Hong Kong Special Administrative Region have identified the need for a major new water treatment and transfer scheme. The project now under construction will comprise a 1.2 km long raw water aqueduct, a major new 0.25million cubic metres per day water treatment works (with space for upgrading to 1.2Mm³/d), a 12.1 km long treated water aqueduct and a primary service reservoir.

Jan 1, 1999

By Fengyu Ren, Kunpeng Yu, Gideon Chitomb, Qiangqiang Gao, Liqiang Ma, Jiangtao Zhai, Ichhuy Ngo

The penetration of rock fragments of overlying strata causes advanced ore dilution during drawing. The results of numerical and physical experiments showed that the proposed numerical simulation was applicable and the microscopic parameters of the model were reliable. The penetration under the variables of particle diameter ratio, density ratio, overlying strata thickness, and particle morphology was clarified. The penetration was quantitatively characterized by the discharge amount and the dilution rate. The experimental results showed that the diameter ratio and density ratio had a significant influence on the penetration. On the irregular shape of particles, the penetration is weakened. The overlying strata thickness had little effect on the penetration. This study could provide a theoretical basis for the full section uniform drawing, avoiding advanced ore dilution and further optimization of recovery rate.

Nov 13, 2023

By Geoffrey Berry

Exposure?response relationships between the relative risk of lung cancer and quantitative measures of exposure to asbestos are available from a number of epidemiological studies. Meta-analyses of these relationships have been published by Lash et al. (1997) [Lash, T.L., Crouch, E.A.C., Green, L.C., 1997. A meta-analysis of the relation between cumulative exposure to asbestos and relative risk of lung cancer. Occup. Environ. Med. 54, 254?263] and Hodgson and Darnton (2000) [Hodgson, J.T., Darnton, A., 2000. The quantitative risks of mesothelioma and lung cancer in relation to asbestos exposure. Ann. Occup. Hyg. 44, 565?601]. In this paper, the risks derived in these meta-analyses have been compared. Lash et al., concentrated on process and found that the risk of lung cancer increased as the asbestos is refined by processing. Hodgson and Darnton concentrated on fibre type and found that the risk was highest for exposure to amphibole asbestos (crocidolite and amosite), lowest for chrysotile and intermediate for mixed exposure. Some of the differences between the conclusions from the two meta-analyses are a consequence of the choice of studies included. The range of asbestos types included in the studies in the analysis of Hodgson and Darnton was wider than that in Lash et al., enabling differences between fibre types to be analyzed more readily. There are situations where occupational exposure to chrysotile asbestos has shown no detectable increase in risk of lung cancer. Taconite miners have shown no increased risk of mortality due to lung cancer. © 2007 Elsevier Inc. All rights reserved. Keywords: Mesothelioma; Amosite; Grunerite; Taconite; Crocidolite; Tremolite; Anthophyllite; Winchite; Risk assessment; Etiology

Jan 1, 2007

By Priscilla P. Nelson, Yousof Abd Al-Jalil, Christopher Laughton

Prediction of excavation rates is a critical element in the pre-planning of a tunnel boring machine (TBM) project. A realistic evaluation of performance expectations is needed that reflects both the knowns and unknowns of the excavation process and geologic conditions. Current planning procedures are often based on deterministic “best guess” estimations. In this paper, a probabilistic approach to performance simulation is presented that will permit rational consideration of general and project-specific uncertainties in establishing realistic performance estimates. Companion to the simulation software is a database of over 600 public-domain case histories.

Jan 1, 1999

By E. Sabina Brady

Over the next two decades there will be significant trade and development opportunities in China for mining, engineering, equipment, and construction companies interested in becoming part of the development of China&apos;s chemical and fertilizer industries. At last count, China&apos;s phosphate ore reserves of 11.8 Gt (13 billion st), ranked fourth in the world behind the US, the USSR, and Sahara-Morocco. However, a recent statement by the head of the Ministry of Geology and Minerals, Sun Daguang, claims that with increased prospecting in the last few years, China&apos;s phosphate reserves now rank first in the world. Whatever the actual size of its known and potential reserves, China&apos;s present phosphate processing capabilities fall far short of demand, while the substantial progress that has been made in this area points out the severity of the problems that still remain. Since 1949 China has developed 181 mines and increased its phosphate concentrate production from 10 kt (11,000 st) to 10.86 Mt (11.97 million st). By the 1980s, China was the third largest chemical fertilizer producer in the world-although this claim is slightly misleading as China&apos;s nitrogen/phosphate potassium ratios are far from average world ratios and even further from US standards. According to the Sixth Five Year Plan promulgated in 1982, the country&apos;s development plans emphasize the expansion and upgrading of key energy and industrial sectors, including that of fertilizer production-specifically phosphate and potash. Within the framework of the plan, the Ministry of Chemical Industry&apos;s development priorities are to: • Increase potash production by 150% to 50 kt (55,115 st). • Raise phosphate fertilizer production 21.2% to 2.8 Mt (3.1 million st), 46 kt (50,705 st) of which will come from new projects constructed and completed within the Sixth Five Year Plan, with projected new production of phosphate concentrate and complex fertilizer in the next decades totaling 500 kt (551,146 st). • Commence work to increase phosphate ore production by 8.33 Mt (9.18 million st). Facilities for 2.43 Mt (2.68 million st) will be completed and come on stream by 1985. • Commence work to increase iron pyrite ore production by 3.69 Mt (4.07 million st), facilities for 2.9 Mt (3.2 million st) will be completed and come on stream by 1985. • Verify 600 Mt (661 million st) of new phosphate ore reserves. Since the promulgation of the Sixth Five Year Plan, Chinese authorities have announced that 70 key construction projects will receive top priority in the implementation of the plan. These projects include five in the chemical industry area, including the construction of four fertilizer plants in Urumqi (Xinjiang), Zhenhai (Zhejiang), Beijing, and Lucheng (Shanxi), and a pyrite mine in Yunfu (Guangdong). In addition, by 1985 the state will expand or construct three major phosphate mines: Wangji in Hubei, Kaiyang in Guizhou, and Kunyang in Yunnan. Fertilizer Ratios In 1982, China&apos;s fertilizer production was slightly higher than 12 Mt (13.2 million st) and consisted of 80% nitrogen, 19% phosphate, and 0.19% potassium. By 1985, state officials project that fertilizer production will reach 13.4 Mt (14.8 million st) and consist of 78.4% nitrogen (10.5 Mt or 11.6 million st), 21.2% phosphate (2.8 Mt or 3 million st), and 0.39% potassium (52.3 kt or 57,605 st). To attain the world average using the country&apos;s 1985 projected production level for nitrogen, China will have to double its 1985 phosphate production to 5.76 Mt (6.35 million st) and increase its 1985 potassium production almost 80 times to 4.1 Mt (4.5 million st). These numbers demonstrate the seriousness of the fertilizer production problem in China today and the long-term nature of the problem&apos;s solution. Development Examples Yunnan is the third largest phosphate-rich province in China with verified deposits of 1.9 Gt (2.1 billion st). Despite this abundance, the province only mines around 3 Mt (3.3 million st) of phosphate rock annually. In June of this year, Yunnan announced its intention to initiate 39 development projects within the next two and a half years, requiring an estimated $200 million worth of foreign investment. The three areas receiving the most emphasis will be:

Jan 9, 1983

By A. Bruynesteyn

Procedures are discussed to determine if a waste material can become acid producing when left exposed to the environment. When wastes proves to be acid producing, methods are described that can be used to determine the characteristics of the effluents produced from a commercial size waste dump, taking into consideration that large quantities of pollutants can accumulate inside a waste dump during dry periods. The length of such dry periods and the quantity of rainfall greatly affect effluent characteristics.

Jan 1, 1980

By Surendra K. Mishra

With increasing regulatory pressure from the environmental authorities, waste management has become a focal point of industrial operation. To offset the waste management costs, industry has made conscious effort to recover usable resources from the waste streams. This paper reviews the technical developments and current practices in processing of waste materials. Methods for recovering metallic, non-metallic and organic species from solid wastes and effluents generated by operating plants are discussed.

Jan 1, 1997

By John E. Tilton

Real copper prices during the past several decades display two striking characteristics. First, they are highly volatile. Within a year or two, copper prices can rise or fall by 30% or more. Second, over the longer term, they are falling. Indeed, since 1970, the secular trend price for copper is down by more than 50%. Figure 1 highlights both of these characteristics. It shows the average annual US producer price for copper since 1970 measured in constant 2001 US dollars. While the London Metal Exchange (LME) copper price is not shown, it and the US producer price have for some time moved more or less together. So pronounced short-run fluctuations around a significant long-run decline describe copper prices, not only in the United States, but around the world.

Jan 1, 2002