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By R. R. Rollins

Field data combined with theoretical derivations were used to design a surface mining operation using explosive casting. Calculated casting results varied from 44% to 65% depending on bench height. The field tests were performed at an Eastern, contour, coal stripping operation. Results from five experimental casting shots, using a shovel and trucks, are summarized and compared to conventional mining methods. The overburden material removed by casting ranged from 35% to 65%, with an average of 50%. Fragmentation was improved, and it was demonstrated that this procedure is economically attractive, with a resultant cost savings of $0.59/m3 or $5.93/t of clean coal.

Jan 1, 1988

By K. N. (Mani) Subramanian

A 2.5 meter diameter column has been successfully used in a 100 tph flotation plant at the Harbour Lights Mine in Leonora, Western Australia, to produce a final gold bearing sulfide concentrate from the ore in a single stage. This pioneering application of column flotation cells to rougher stage was pilot tested using a 11 cm column, which demonstrated column's capability in rougher, scavenger and cleaner flotation stages. A hybrid circuit involving columns and mechanically agitated flotation cell s was adopted for the commercial installation. This paper describes pilot plant results, design of the plant flotation circuit, and early results of commercial operation.

Jan 1, 1988

By K. S. Shivakumar, R. Bhima Rao, M. R. Patil

Liberation size can be estimated using various techniques such as grain counting, frequency curves, X-ray intensity and the mesh of grind. The present investigation deals with the estimation of the liberation size of graphite flake contained in a schistose ore from Shivaganga, India. It was observed that the flakes are liberated at from 75 to 150µm. The rougher flotation concentrate obtained after grinding the run-of-mine ore for 5 min contained 54% fixed carbon. This represented the first stage of liberation. After regrinding to <90 µm in the presence of sodium silicate and guar gum, a cleaner concentrate containing 82% fixed carbon was obtained.

Jan 1, 1998

By Levent Ozdemir, Roy H. Spitzer, Don W. Deere, John B. Blyler

This paper documents the construction of the Stanley Canyon Tunnel, the geologic conditions encountered, boreability of the rock, and the impacts of the conditions encountered on the construction. The 5.05 kilometer long (3.1 miles), 3.47 meter (11.4 feet) diameter, tunnel was driven through granites with a refurbished tunnel boring machine (TBM). Difficult ground conditions encountered included shear zones, high groundwater flows, and hard, tough, and strong rock. Detailed geotechnical studies during construction revealed that microscopic changes in the rock grain boundaries due to contact metamorphism, resulted in the hard boreability. Originally scheduled for five months, the tunnel construction required nearly three years, including periods of project shutdown.

Jan 1, 1995

By S. K. Kawatra, T. C. Eisele

Production of highly-cleaned coal for advanced utilization schemes requires close control of the coal ash content at very low levels. For this purpose, a sensitive, low-cost, robust on-stream ash analyzer is needed. The development of such an instrument based on x-ray backscatter and fluorescence is described, including features to improve its sensitivity at low ash levels. The performance of the resulting device in testing a real coal sample is discussed.

Jan 1, 1990

By S. Donges, P. L. Dunstan, B. J. Huls

The commissioning of a distributed digital control system for the grinding circuit at Cuajone was completed by mid-August 1985. Development of a successful strategy, excellent operator acceptability, and the visual aspects offered by the display of the central console improved mill through- put significantly. The inherent features of a digital system enhanced the flexibility in grinding control and allowed the milk and classifiers to be operated at maximum capacity. This paper discusses the strategy development and the production restrictions encountered, and evaluates the overall performance of the digital control system.

Jan 1, 1988

By M. Kuchta

A linear integer programming (MIP) model to solve the long-and short-term production-scheduling problem for sublevel caving operations is presented. The MIP model is designed as a multi-time-period problem to provide monthly schedules that meet production, blending and sequencing requirements. One of the most important issues during the development of the MIP model was the requirement of sequencing between blocks. In this mathematical model, unique constraints that ensure sequencing of the production from sublevels are developed. A suggested method of handling a large number of variables is also given. The MIP scheduling model was implemented on a data set obtained from the Kiruna Iron Ore Mine located in northern Sweden. The initial MIP model implementation was successful and provided a solution that optimized resource recovery while meeting monthly and yearly production constraints. The scheduling results obtained based on the Kiruna Mine are further presented and discussed.

Jan 1, 2003

By F. Sill

The disposal of residual material from processing and combustion of coal, from incineration of domestic refuse and sewage sludges kind to the environment is a prior task for the future. Deutsche Montan Technologie (DMT) has developed a new technique which makes possible to fill-up goaf cavities behind running caving systems in coalmining. In a mixing and pumping station on the surface high concentrated suspensions are produced from the above mentioned materials. The paste is pumped through pipes to the coalfaces and via trailing discharge pipes stretched to the fracture zone in the caved-in goaf. Since three years a special designed plant is working successfully on a coal mine of Ruhrkohie AG.

Jan 1, 1994

By W. W. Simpson, S. A. N. Sheya

A procedure was developed by the U.S. Bureau of Mines for recovering gold, silver, cobalt, copper, and zinc from a massive sulfide ore by a hydro-metallurgical process. The procedure consists of (1) oxygen pressure leaching; (2) iron, arsenic, and copper removal from the leach solution by precipitation; (3) selective extraction of cobalt and zinc from solution; (4) electrodeposition of the cobalt and zinc from the strip liquor; and (5) cyanidation of the pressure leach residue to recover gold and silver. The results are discussed in terms of efficiency of metal recovery and conclusions drawn as to possible benefits and broad applications of the process.

Jan 1, 1990

By B. Amadei, A. Squassabia

This paper introduces the Rock Mass Median (RMM) index, a statistical measure of the mechanical quality of a rock mass thus is obtained through a mechanistic interpretation of the Poisson stochastic process. This process is the theoretical foundation of the Exponential Model, a probability distribution successfully used in practice to describe the spacing of discontinuities in rocks. Building on the Exponential Model, a simple method to compute RMM based on a widely accepted mechanical quality index is also presented. Verification is per formed through the analysis of two sets of core samples. Hypothesis testing at the 5% level of significance supports the validity of RMM for these samples.

Jan 1, 1994

By Jacques L. Mauboussin

The EUROPEAN ORGANIZATION for NUCLEAR RESEARCH (CERN) has undertaken the construction of a LARGE ELECTRON POSITRON COLLIDER (LEP), near GENEVA (Switzerland). The facility includes the main 27 km long tunnelled ring, 18 shafts, 20 experimental caverns and many auxiliary galleries. Roughly 800 000 cu.m were excavated in the molasse at 50-140 m depths, using roadheaders for caverns and auxiliary tunnels and 3 WIRTH, 4.5 m diameter, fullface TBMs for the main circular tunnel. Each TBM performs 25-30 m/day. Provisory lining behind them uses either precast concrete elements or shotcrete. Works a e being carried out by a joint-venture of European contractors led by FOUGEROLLE (France).

Jan 1, 1987

By Franz Deix, Bernd Braun

A sensitive portion of Section U 6/3 of the Vienna, Austria subway system required construction of two single-track tunnels under a telecommunications facility, where strict ground settlement limitations had been set. Local geology, hydrology, and site constraints led to the decision to use the New Austrian Tunneling Method (NATM) supplemented by compressed air and partial dewatering. In addition, ground freezing was used, as the tunnel would pass through alluvial layers beneath the facility, with a cover of as little as 1.5 m. Laboratory testing and two in situ test fields were used to collect frozen soil data so that the freezing scheme ensured minimal heaving magnitude.

Jan 1, 1987

By Michael Schultz, Gregory Sanders

In 2017, the North Texas Municipal Water District (NTMWD) initiated the design of the Sister Grove Regional Water Resource Recovery Facility (SGRWRRF) to provide additional treatment capacity for future population growth within the Lavon Lake watershed. To provide a discharge location for SGRWRRF approximately 4.5 miles of 2.4- meter (96-inch) internal diameter pipeline will be constructed, including 2.3-kilometer (7,800) feet and 487-meter (1,600 foot) long tunnel segments. This paper will discuss the anticipated geology of the two tunnel segments, selection of the tunnel alignment, the anticipated initial tunnel support requirements and other aspects of the project design

Jun 13, 2021

By H. J. Ilgner

Previous applications for using waste rock for backfilling in South African gold mines were reviewed and it was found that in many cases the mechanical equipment selected and the design philosophy applied did not meet the requirements. A more simplified system configuration is proposed, which allows the equipment to be relocated as mining progresses. Innovative high-intensity grinding and dense-phase pumping technology are proposed to provide a low-porosity backfill with a particle top size of 5 mm to 8 mm. According to recent rock mechanics modeling work, this comminuted waste backfill material can provide a good compromise between underground support characteristics and reliable hydraulic transportation behavior.

Jan 1, 2001

By T. E. Wilson

The length of Alaska’s coastline, combined with the presence of a significant number of fjords, encourages consideration of marine disposal of mine tailings. However, since various factors govern the viability of the submarine tailings disposal (STD) option, the decision making process is complex. An expert system, called Submarine Tailings Disposal Expert System (STADES) that will help mining project planners explore the feasibility of STD, was developed. Existing literature, supplemented by engineering recommendations, on the various aspects of marine disposal of tailings was reviewed and formed the knowledge base for the expert system. The shell used to develop the expert system was LEVEL5®.

Jan 1, 2001

By Lynn B. Hales, John A. Herbst, Thomas L. Gabardi

A system for a continuous determination of the charge volume of grinding media in ball mills and SAG mills has been developed. The system, comprised of a unique measurement device and a model based Kalman filter algorithm, determines grinding media level within a mill and calculates media and liner wear rates. The signal from an instrumented washer mounted on the exterior of the mill shell is used to provide the measurement that, along with mill power and on-line models for media mechanics, result in estimates of mill parameters that can be used in media addition control strategies. Data are presented for a 12.5 x 15 ft. ball mill.

Jan 1, 1990

By H. M. Castrantas

Caro&apos;s (peroxymonosulfuric) acid has been reported to destroy WAD (weakly acid dissociable) CN-but, until recently, the technology has not been demonstrated in other than a laboratory setting. During the last two years, Caro&apos;s acid has been shown to successfully detoxify WAD CN-in tailings at two large North American gold mines. Using on-site FMC generators, Caro&apos;s acid reduced the WAD CN-from 40-55 ppm to below 20-35 ppm WAD CN-, the target range for the two mines. The detoxification costs using Caro&apos;s acid were less than 50% of the treatment cost of using hydrogen peroxide, the previous oxidant of choice. In addition to the considerable savings in CN-detoxification costs, lower WAD CN-values were achieved and the detoxification time with Caro&apos;s acid was greatly reduced compared to hydrogen peroxide.

Jan 1, 1995

By L. Bloom

In 1996, lack of confidence in assaying methods and sample handling affected companies as diverse as Bre-X and Timbuktu. Both share prices and the ability to raise financing are impacted when the quality of assay data is suspect. Overseas projects are subject to enhanced scrutiny when local facilities are used that are unfamiliar to brokers, financing agencies and banks. Quality control systems can be -implemented but there are associated costs. These costs should reflect the risk to the mining company, investors and financiers and the size of the proposed investment. In this regard, assay control call is considered a form of insurance to enhance the value of an exploration or mining project.

Jan 1, 1997

By S. Michael Feroz, Michael J. Britch, Frank S. Buehler

The City of Portland is constructing the Columbia Slough Consolidation Conduit as a part of its commitment to reduce combined sewer overflows into the Willamette River and the Columbia Slough. Known as “The Big Pipe,” the conduit has a 3.7 m. (12 ft.) internal diameter and is 5,640 m. (18,500 ft.) long. Construction Segment 1 of the project includes 250 m. (814 ft.) of reinforced concrete pipe (RCP) installed by boring and jacking. Five separate crossings were constructed beneath Union Pacific Railroad tracks and Columbia Boulevard, an adjacent arterial roadway. This paper describes the design and construction of these bored and jacked crossings.

Jan 1, 1999

By G. Barelli, C. Giusti, W. H. Langer

Natural aggregate – sand, gravel, and crushed stone – is the number one non-energy mineral resource in the world in terms of both volume and value. A plan for the sustainable development of aggregate resources can include: 1) policies and economic incentives to encourage identification and protection of potential resources, 2)efficient quarrying and processing of aggregate, 3) efficient use of primary aggregates, 4) greater use of recycled, waste, or substitute material, 5) inclusion of costs of all environmental impacts in price of material, 6) reclamation to beneficial secondary uses, and 7)identification of objectives, targets, actions, and sustainability indicators. Quarrying can also contribute to sustainable ecosystems through natural habitat reclamation.

Jan 1, 2003