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By Hassan Madani, A. Malek Mohammadi

Dorreh barite mine located in the central part of Iran is one of the largest barite mines, in the country. The mine is subdivided into three blocks, which are called block 1,2,3 according the barite quality. In the central part of each block, a heavily concentrated grid of exploratory drill holes have been drilled and the reserves of area was calculated based on these holes, some years ago. It was decided to compute the reserve of the area by geostatistical methods, in the form of an M.Sc. project. In order to study the area, three regionalized variables including density, thickness and density-thickness (accumulation) was studied and the spherical variograms were fitted to these variables. These models were evaluated by cross-validation method. The optimized block size was chosen in order to compute the reserves by kriging method. The reserves of explored parts of each block of mine was calculated and the results were extended to the whole area of the blocks. The reserve of the explored parts and the total reserve of the area were calculated to be 96,000t and 1,670,000t respectively.

Jan 1, 1996

By W. Dresler

Since 1900, smelters have produced in Canada over 10 million tonnes of iron silicate waste slag containing significant quantities of nickel, cobalt and copper. The slag is reduced with aluminum and calcium oxide additions to produce a copper, nickel, and cobalt enriched alloy and an obsidian slag. It was found that the obsidian slag contained very low copper, nickel, and cobalt contents, indeed below 0.06% of each the base metals. These metals have been collected in a type of ferroalloy with up to 1.6% Cu, 2.1% Ni, and 0.7% Co. These alloys can be recycled according to standard procedures in base metal smelters. Surprisingly, the obsidian slag was found to display good cementitious and pozzolanic properties, which is a requirement for cement production. The strength producing properties of the obsidian slag are considered to be exceptional at the 28 day standard test age. In most cases, the obsidian concrete is characterized by significantly greater strengths than control concrete tests and concrete containing fly ash or blast furnace slag. Compressive strength data at 365 days for the obsidian concrete is impressive.

Jan 1, 2003

By Thomas D. Kaufmann

The 1982 recession set the US mining and metals industries reeling. Will the oncoming recession of 1991 hit as hard? Probably not, thanks to a shallower downturn, a weaker dollar and remarkable lower costs. Effects of the last recession That the 1982 recession was traumatic to the American mining and metals industry is an understatement. Quantities of metals consumed dropped. Metals prices fell despite continuing general inflation. The resulting real gross revenues of producers of each of the major metals plunged, in the trough of 1982, to levels one-fourth to two-thirds of those of the peak of 1979 (Table 1). By contrast, most industries in the United States were not hit anywhere nearly as hard. Real GNP, the aggregate of all production, slipped only 1 % from 1979 to 1982. Metals are most sensitive to the business cycle because of their applications. All metals but gold are raw materials to downstream industries. Raw materials are victims of strong fluctuations. This is because buying industries try to hold high inventories in boom periods when goods are in short supply. They reduce inventory levels in buyers markets when suppliers have idle capacity and raw materials are in ample supply.

Jan 1, 1990

By Levent Ozdemir, Russell Miller, Fun-Den Wang

The full utilization of tunnel boring machines for excavation in medium hard and hard rock has been limited by insufficient knowledge of rock behavior under the action of mechanical cutters. An understanding of factors affecting the rock removal process will permit: (1) the more efficient design of tunneling machines, (2) the prediction of boring performance from geologic data and cores taken from the proposed tunnel alignment, and (3) an improved excavation rate, thus a lower tunneling cost.. The Colorado School of Mines, under the sponsorship of the National Science Foundation, is studying the effects of a number of parameters in regard to tunnel boring using both full and small scale laboratory tests, analyzing field boring performance and comparing the laboratory and field data. Results indicate: (1) the field boring performance can be reproduced in the laboratory, (2) the optimum spacing of cutters or optimum spacing to penetration ratios may be found in laboratory testing, (3) it is promising to use small core samples and laboratory testing to predict field machine performance and (4) effect of joints on boring rate is significant and should be included in predicting tunnel boreability.

Jan 1, 1974

By J. H. Lalor

The Olympic Dam deposit was discovered in July 1975 with the intersection of 38 m (125 ft) of 1.05% copper in diamond drill hole RD 1. A further eight holes were drilled with only marginal encouragement to November 1976 when RD 10 cored 170 m (558 ft) at 2.12% copper and an economic discovery was confirmed. The discovery of Olympic Dam is an excellent example of the application of broad-scale scientifically based conceptual studies to area selection combined with the backing of an exploration management willing to support its exploration scientists in testing their ideas with stratigraphic drilling. It also illustrates the persistence required in mineral exploration. The project began in 1969-1972 with the development of a conceptual model for the formation of sediment-hosted copper deposits. This model suggested that the alteration of continental-type basaltic rocks could release copper into solution from which it could be concentrated in favorable stratigraphic positions. In mid-1972, this concept was applied to a review of the Proterozoic and Lower Paleozoic rocks in South Australia aimed at defining targets for stratigraphic copper deposits.

Jan 1, 1991

By Jack E. Fraley, Robert E. Simpson

INTRODUCTION Spokane Mining Research Center (BuMines) is researching sealants for underground coal mines to: 1. Reduce sloughing of shale roofs. 2. Reduce sloughing of coal ribs. 3. Seal block stoppings against air losses. 4. Construct stoppings by spraying over jute cloth or metal lath. 5. Render incombustible in-place polyurethane foam. Originally the work was directed towards reducing sloughing of shale roofs. Many underground coal mines have shale directly over the coal which weathers severely after exposure to the mine atmosphere. Lab investigations(l, 2, 3, 4) have shown that many shales separate into layers when immersed in water or stored in a high relative humidity environment. Upon drying or after removal from high humidity, the shales continue to separate. Underground coal mines become wet in the warmer months from condensation of the ventilating air. Conversely, the mines become dry in the cooler months from evaporation. The mines experience severe shale break-up during the summer and much less break-up during the winter. Figs. 1, 2 and 3 show weathered shale roofs. in underground coal mines. Fig. 4 shows fallen shale on the entry floor. Sealing the shale reduces this sloughing problem.

Jan 1, 1974

By J. G. Groppo, B. K. Parekh

A series of performance studies were conducted using countercurrent column flotation to recover a marketable clean coal product from existing preparation plant fine waste streams. The test work was conducted at several preparation plant sites in Kentucky and Virginia using a 150-mm (6-in.) inside diameter column that was 5.8 m (19 ft) high. Both thickener feed and classifying cyclone overflow with a typical size distribution of 150 µm (100 mesh) X 0 were tested. The percent solids of the column flotation feed varied from 1.5% to 15% while the ash content ranged from about 30% to 60%. The concentrates produced contained 2% to 10% ash with Btu recoveries of nearly 90% using 0.12 to 1.25 kg/t (0.25 to 2.5 lbs per st) fuel oil and 0.12 kg/t (0.25 lbs per st) MIBC. These results were consistent with or better than results obtained in preliminary laboratory scale column flotation evaluation. Test results from seven different seams are discussed as well as scale-up relationships used to design a full-scale installation presently in operation.

Jan 1, 1991

By Victor J. Scaravilli, C. Richard Linamen

This paper presents a case history of Southwest Interceptor Contract No. 1, Cleveland, Ohio. It details some of the problems and solutions of handling and erecting precast concrete segments in a small bore soft ground tunnel. It also reviews how specific interpretations of contract requirements and contract administration effect production, performance and productivity.

Jan 1, 1987

In a future world of 8.5 billion people in 2035, the Energy Information Administration's (EIA) projected 50% increase in energy consumption will require true "all of the above" energy resource use from oil, gas, renewables, nuclear, and coal. In particular, coal will continue to be the world's energy cornerstone, providing more incremental energy over that same time period than any other single fuel. Coal has long been a centerpiece of a low-cost, high-reliability electricity grid. Today there are 1.3 billion people across the globe without access to electricity and 2.7 billion people who do not have clean cooking facilities. The problem is spread across the developing world, but it is particularly severe in sub-Saharan Africa and developing Asia, which together account for 95% of people in energy poverty. Without a commitment to achieve universal energy access it has been estimated that by 2030, there will be an additional 1.5 million premature deaths per year caused by household pollution from burning wood and dung and through a lack of access to clean water, basic sanitation and healthcare. Modern energy sources are essential to meeting these challenges.

Jan 1, 2012

By A. C. Beaulieu

CITY OF EDMONTON Rate of Growth The City of Edmonton has been classed by some economists as being the most progressive City in Canada since the early 50's. The high rise buildings that are changing Edmonton's skyline, the rapidly expanding sewer and water network, and the proposed rapid transit system all indicate the requirements of an ever expanding City. Edmonton, the core of Canada's Energy Empire is the country's seventh largest metropolitan area. Bisected by the 22 mile long park of its magnificent river valley, it sits in the midst of the 50,000 sq miles of riches that have created it. Underneath the City, however, extending down for thousands of feet and encircling it for a radius of scores of miles, lies a fabulous store of petroleum wealth. By the early 1940's, based upon the needs of the farming areas, accompanied by some small exploitation of coal and timber, Edmonton grew to 100,000 people. Then in a short space of 20 years Edmonton shot up to be a city of 450,000. Figure 1 (Slide No. 1) indicates the population growth in the City of Edmonton and the Census Metropolitan Area from 1906 to 1971.

Jan 1, 1997

By R. H. Seraphim

The name is derived from an Egyptian myth, "A beautiful lone bird which lived in the Arabian desert for 500 or 600 years and then consumed itself in fire, rising renewed from the ashes to start another long life." HISTORY This account of the first history is gleaned from old reports and documents which are listed in the Bibliography and from discussions with old-timers of the district. Prospectors were active in the vicinity of Greenwood in 189 1, and in that year staked the Mother Lode, Crown Silver, and Sunset. Henry White staked the Knob Hill claim in Phoenix on Jul. 15, 1891, and by the end of the year, other prospectors had staked most of the claims covering the valuable ore bodies in the camp. Much surface work done in the early years indicated that the values in copper, gold, and silver were low. Large capital investments were required to develop the ore bodies and build smelters. The discovery that the ore was practically self-fluxing greatly enhanced the value of the deposits. A map of the area showing the geology is given in Fig. 1. The bedded Brooklyn conglomerate is shown in Fig. 2.

Jan 1, 1991

By John D. Shaw

1. Introduction 2. The Hydraulic Mine _ (i ) Development (i i ) Extraction ( i i i ) Transport 3. The Water Circuit 4. Manpower and Results 5. Modifications 6. Conclusions 1. Introduction The Kaiser Resources Ltd. hydraulic coal mine is located in south eastern British Columbia, Canada, at the western end of the Crowsnest Pass, next to the Town of Sparwood. The seam presently being mined is the number 10, known locally as the Balmer seam, which is a high quality coking coal, 50 feet in thickness and of an average inclination of 35 degrees. The mine was designed in the late sixties as a small scale trial unit, and was to use a single monitor unit, working 3 shifts per day on a 5 day per week basis. Experience has proved the method to be so successful as to warrant the expansion of the ancilliary facilities to cater for the increased production. The annual raw coal production from this single monitor unit has risen from 108,988 short tons in 1970 to 942,334 short tons in 1975, with a total mine labour force of about 160 men including the surface de-watering plant, mine supervision and mine administration.

Jan 1, 1977

By Robert W. Bartlett

Heap biooxidation of sulfidic refractory gold ore requires large amounts of oxygen, as shown in Figure 1. Bacteria, Thiobaci/lus ferrooxidans, are donnant at oxygen concentrations below about 3% in air (1 ppm in aqueous solution) because ofmonod kinet­ics. Hence, the maximum possible utilization is only about 75%, and it may be much less than that due to poor air sweep effi­ciency. At the maximum oxygen utilization, an ore containing two percent pyrite requires nearly 100 cubic meters of air per tonne (4,000 cubic feet per ton). The stoichiometric air require­ment to oxidize arsenopyrite is similar to that of pyrite. While the leaching solution percolating through the heap introduces some dissolved oxygen, the amount is insignificant because of the low solubility of oxygen in water, 7 to 8 ppm at atmospheric saturation. There are only three ways to provide oxygen to the heap: either air flow by natural convection, diffusion of oxygen from the surface (through stagnant air in the air-filled void space in the heap), or forced air ventilation of the heap. Each of these processes will be reviewed.

Jan 1, 1996

By G. I. Voiloshnikov, A. F. Panchenko, N. S. Voiloshnikova

Low world gold prices stimulate development and introduction of economically efficient ( cost saving) technology for operating gold mills. This report covers the results of testing and introduction of CIL technology to recover gold from flotation concentrate of Samarta gold concentration plant located in Buryatia (Russia). This plant is treated the ore of Zun Kholba gold deposit using gravity and flotation of gravity tails as preconcentration processes. Till recently high grade gold gravity concentrate was smelted to gold bullion and shipped to gold refinery, gravity middlings were leached by cyanidation in cone type equipment developed by Irgiredmet and flotation concentrate shipped to copper smelter. The disadvantages of flotation concentrate shipping to copper smelter are following: high concentrate transport cost; problem with gold shipped balance; high cost of flotation concentrate treatment; comparatively low gold recovery. In this connection IRGIREDMET developed the hydrometalurgical technology for gold recovery from flotation concentrate. The flowsheet was developed on the base of laboratory, pilot plant and industrial scale tests conducted by IRGIREDMET in 1987-1997 and lrgiredmet experience on CIP process testing and industrial scale introduction in Yakutia [1-6]. The flowsheet is presented in Fig.1 and consists of following base operations: concentrate regrinding;

Jan 1, 1999

By William J. Maloney

Blind drilled shafts are becoming increasingly popular as a secondary and sometimes primary means of ventilation. This is particularly true in the Appalachian coalfields. Some reasons for the rebirth of blind shafts are economics, timeliness, safety characteristics and their inherent independence from underground operations. Blind drilling has had limited use in hard rock and tunneling ventilation. Advances in cutters, bit design, equipment and lining systems have made blind drilled shafts the shaft construction technique of choice for ventilation specialists. History of blind drilling Blind drilling's roots include the Nevada test site, the coalfields of Appalachia and Germany, and the uranium mines of Arizona. Early technology was developed using a variety of equipment mainly of oilfield origin. Shafts completed by oilfield equipment ranged from the shallow 1.5 and 1.8 m (5 and 6 ft) lined shafts on the Nevada test site to two 3 m (10 ft) lined, 222 m (730 ft) deep shafts in Alberta for heavy oil development. Several of these shafts were completed to extraordinary depths. The record, completed in 1969, is a 2.28-m-diam (90-in.-diam), 1875-m (6150-ft) deep shaft, located in the Aleutian Islands of Alaska.

Jan 1, 1993

By D. Sotiropoulos

In the recent years, the mining sector is looking for specific indices, taking into account economic, environmental and social criteria, in order to meet the sustainable development requirements. In the present study traditional and environmental sustainable indices used in the Agios Dimitrios Power Plant, Northern Greece, are compared to those of ESKOM Company, South Africa, taken as reference. These indices are referred to, a) the solid fuels consumption, such as lignite, and, b) the emissions to the atmosphere, such as SO2, NO2 and dust. Last five years data show a remarkable improvement of all indices in the Agios Dimitrios Power Plant. Although the lignite used in this Power Plant is by far of poorer quality than that used by ESKOM - net calorific value 1272 and 4638 kcal/kg, respectively - dust emissions in both Power Plants are similar (52 and 31 g/kWh, respectively). The SO2 and NO2 emissions are very low in Agios Dimitrios compared to those of South Africa, respectively 1.92 and 7.91, and 1.74 and 3.61 g/kWh. This is mainly due to natural desulfurization (by the lignite?s calcium content) and the low NOx burners.

Jan 1, 2003

By Russell K. McFarland, Gloria T. Saxton

Introduction The March 1969 issue of Civil Engineering contained on article entitled "BART" Subway Construction: Planning and Costs" authoried by Thomas R. Kuesel. This article describes in some detail the innovations developed in planning and management to undertake the design and construction of the BART Project. This 75 mile long system contained 17 miles of urban tunnels and 13 subsurface stations. Within this article Mr. Kuesel very nicely listed the cost of the 70,000 linearfeet of bored tunnel, 23,380 linearfeet of cut and cover tunnel, and the costs of the thirteen underground stations. Ten years subsequent to the publishing of Mr. Kuesels article, it is very sobering to realize that San Francisco obtained a bargain of a magnitude that we are just beginning to realize. Table 1 is a listing of tunneled line sections taken from the paper. The average cost shown in this figure, including sections constructed under compressed air is $1,620 per foot of tunnel, with bid dates ranging from June 1966 thru October 1968. This average cost translated to about $16 million per double track mile of twin tunnel system.

Jan 1, 1979

By Harold L. Hinds

The refining of precious metals from steel wool cathoodes is completed by one of two methods: 1) By direct fire smelting or: 2) Acid treatment of the cathodes to dissolve the steel wool and then followed by fire smelting. To further the refining of the cathodes, the Miller Process and the Wohlwill Process are used.

Jan 1, 1981

By John C. Balla

The Spar Lake deposit is located in northwestern Montana, approximately 27 km (17 miles) south of Troy, MT, under Mt. Vernon. The deposit is a stratiform, stratabound copper-silver deposit occurring in the Revett Formation of the Proterozoic Belt Supergroup. Distribution of known sandstone-type deposits in the Revett Formation is shown in Fig. 1.

Jan 1, 1991

By D. A. Dahlstrom

Crushing and grinding consumes about 1.3% of the nations produced electrical energy.( Furthermore, only one in the first ten highest consumers comes from an industry other than mineral processing. This is the grinding of wheat to make flour. The other nine are all in the metallurgical industry and are easily the largest consumers.

Jan 1, 1988