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By Yoginder P. Chugh

The mining methods used at many opencast brown coal mines in Poland and the German Democratic Republic are not used in the US to any extent. Using bucketwheel excavators, bucket chain excavators, and mobile conveyor bridges, the mining techniques may offer efficient, economic alternatives for operators in the US. These mining methods were observed during visits to several open-cast brown coal mines in Eastern Europe over the past two years. Some of them may be particularly attractive for the large lignite mines being planned in North Dakota and Texas.

Jan 11, 1980

By S. Behl

A major limitation in developing successful selective, flocculation schemes is the difficulty encountered in adsorbing the polymeric flocculant only on the desired substrate. In this paper, a correlation between selectivity of flocculant adsorption and separation efficiency is outlined, and a potential technique to achieve selective adsorption of flocculants is discussed.

Jan 1, 1994

By Trevor J. Smith, Kevork A. Chouzadjian, Rob S. Burns, Steve J. Roden, Michelle A. Spieth

Investigations were undertaken to improve the recovery of silver from CRA's Hidden Valley gold/silver deposit by the addition of calcium peroxide. The addition of 0.75 to 1.5 kg/mt of calcium peroxide improved silver extraction by 5 - 300 and reduced cyanide consumption by up to 30%. Gold extraction was also marginally improved in some of the tests. The results are of economic interest and plant trials will be initiated once operations are underway.

Jan 1, 1990

By Daniel P. Farjeat, Hector A. Canseco, Juan M. Schmitter

Since the early sixties, tunneling in the soft clay of Mexico City, has been done with the aid of open face shields and recently with compressed air. The use of pressurized shafts up to 1.5 kilograms per square centimeter, (147 kilo pascals) with vertical locks to launch the shields, have been used in two cases. After advancing almost 200 meters of tunnel, the same vertical locks were transformed into horizontal locks, to continue the work. Due to the high decompression times involved, it was necessary to install long locks, using the tunnel itself as part of the system. This article describes those cases.

Jan 1, 1981

By L. Lichty

Treatment of refractory gold ores containing arsenic has always presented a major problem in their processing to recover the contained precious metal values. The major difficulties are concerned with lower recoveries and production of hazardous fumes, effluents and residues. Due to these arsenic related problems, many otherwise economically attractive precious metal deposits and dumps all over the world are not exploited. In recent years, treatment processes for refractory gold ores and concentrates have been explored. A few commercial operations employing roasting or pressure leaching have resulted. Roasting has limitations due to environmental constraints related to off gases. Pressure leaching involving high temperatures (180° to 200° C or 356° to 392° F) and pressures (2.75 MPa or 400 psi) is accompanied by high capital and operating costs.

Jan 1, 1990

By H. V. Scotland

Lafarge Corporation's Texas Quarry, in Baltimore MD, achieved a substantial expansion of pit reserves by removing an inactive underground mine. The daylighting program, designed, and completed in 1997, open pit mined more than400 meters of room and pillar workings which were originally developed to recover high brightness Calcium Carbonate. The project proved to be a challenge throughout its course as the pit plan was modified and successful daylighting techniques were developed to remove the mine without adversely affecting the safety of the operation, quality of the stone recovered, or negatively impacting the surrounding community. The design parameters and techniques developed and implemented at Texas may prove of interest to other operators as they are faced with daylighting opportunities. This article will detail the challenges we faced and the solutions which made the project a success.

Jan 1, 1999

By Richard J. Frechette

Final reclamation of mine tailings impoundments typically involves addressing the broad issues of surface stabilization and water management. Surface stabilization includes immobilizing the tailings particles and providing long-term protection of the containment facility. Water management typically includes provisions for handling both the external water (rainfall and runoff) and the internal water (pore fluids). Wet tailings disposal facilities, and sites with limited access and steep topography, present challenges to implementing effective surface stabilization and water management plans. This paper presents a generalized discussion of the approach to tailings impoundment reclamation based on project experience.

Jan 1, 1995

By Thomas S. Bubanovich

This paper will discuss the installation and operation of the Mundix Monitoring System at the Freeman United Coal Mining Company's Orient No. 4 Mine. Detailed explanations of the objectives set by Management, description of the mine, description of the system, installation procedures, and material used, operating procedures, maintenance procedures, and personnel requirements as well as experiences with carbon monoxide monitoring.

Jan 1, 1987

By Haydn H. Murray

A hydrothermal bentonite located in the high Sierras in Nevada is being mined and processed for use as a natural dietary supplement. Because hydrothermal clay deposits are normally zoned and not uniform in composition, a special stockpile was constructed to assure uniformity of processed products. The stockpile of clay was layered and rectangular in shape. Channel samples were taken from 10 locations around the stockpile and were mixed and quartered to provide representative samples. The samples were then chemically and mineralogically analyzed. The results showed excellent uniformity. The mineralogy and chemical analyses will be discussed in the paper.

Jan 1, 2005

By R. L. Grayson

Compliance standards for respirable dust, which are reduced because of high quartz concentrations, have become an industry-wide problem. Research on the physical and chemical character of quartz-classified particles in respirable coal mine dusts indicates that they may exist in intermixed layers or may he coated by clay or coal material. The relative amount of intermixing varies with the coal seam being mined. If most of the quartz particles of a mine dust are "pure," then the dust may have a high fibrogenic risk potential because of truly free silica and the compliance standard should he lowered. If, however, the quartz is locked inside another material matrix, or coated, a reduced compliance standard may not he appropriate.

Jan 1, 1991

By Leslie S. Rubin, John C. Roberge, Mackenzie Burnett

A self regulating helical inducer has been developed and tested for dry injection of coarse or fine solids into a hydraulic pipeline. This centrifugal pumping device has also been modified and tested for use as a boost pump in medium and long distance pipeline haulage systems. The helical inducer has been operated as an integral component of a slurry injection vehicle. This compact, low profile vehicle also includes crushing and screening components, solids feeding components, a track drive system for mobility and is run by a single operator. The helical injector and boost pump operate without speed and flow controls allowing for the practical hydraulic transport of excavated materials.

Jan 1, 1983

By Michael Brittan

For several years, Independence Mining Co. (IMC) has routinely used oxygen fluid-bed roasting to pre-oxidize refractory gold ores ahead of conventional carbon-in-leach (CIL) processing. Oxygen serves jointly as the fluidizing medium and the combustion gas. This technology has proven to be reliable, environmentally sound and cost-effective. IMC is a subsidiary of the Minorco group. The company operates the Jerritt Canyon (a joint venture with FMC Gold) and Big Springs gold mines in the Independence mountain range north of Elko, NV. Ore bodies in the range contain characteristic refractory ore. It requires pre-oxidation ahead of conventional CIL processing. This article describes the technology developed specifically to treat these difficult ores.

Jan 1, 1995

By D. A. Robbins

Remote sensing for environmental measurements is already being used. Aircraft-mounted imaging spectroscopy has been used to evaluate historical mining operations, as well as active mine sites. To the extent that remote sensing can provide more sensitive, cost effective and timely monitoring potential, the technology is of interest to the industry. Questions, however, remain about the application and validation of the data and concerning the availability of the technology in the private sector. This paper discusses some of the potential uses, benefits and concerns related to remote sensing. And it discusses efforts to monitor the technology's development.

Jan 1, 2000

By E. H. Partelpoeg, B. G. Belew

In 1990, the Chino Smelter completed the construction of a plant designed to recover metal values and water from smelter scrubber effluent. Equipment was installed to maximize effluent recycling and minimize costs. The process utilizes magnesium hydroxide as a neutralizing agent which has the advantage of precipitating copper from solution with minimum generation of solid reaction products. The neutralized stream is clarified, with solids recycled to the smelter for metal recovery while the clarified effluent is recycled to the concentrator for use as process water.

Jan 1, 1992

By J. H. Ahn, J. E. Gebhardt, W. K. Tolley

Color measurements were made for pure minerals, mineral mixtures and flolation froths loaded with different minerals. The research objective eras to correlate color with the composition of mineral streams. An industrially available system consisting of a fiber-optic-based illuminator and detector was used to measure color. The color values of binary mineral mixtures varied according to the type and proportion of minerals in the mixture. The measured color values of mineralized froths in the laboratory and in a commercial flotation circuit were dependent on the amount and type of minerals present.

Jan 1, 1994

By J. L. Post

A near-surface body of readily available Na-montmorillonite is located about 24 km (15 miles) southeast of Fallon, NV. The clay, which forms an irregular deposit about 4.8 km (3 miles) long, lies in altered rhyolite within a fault zone. The clay is similar to Wyoming bentonite but is less uniform in composition and contains less MgO and more Fe2O3 in its crystal structure. The clay interlayer cation population can be estimated by using a modified DTA procedure. With selective mining, the industrial properties of the Nevada clay are adequate for use as drilling mud, in foundry applications and as a sealant for hazardous wastes and canals.

Jan 1, 1997

By R. Todd Swinderman

Impact cradles are installed below the belt in conveyor loading zones to cushion the forces from material loading. In this paper, the author will discuss the need for and then explain the new CEMA standard for engineering of impact cradles. He will review the engineering theory and work through an example to demonstrate the assumptions used in the standard do not inappropriately affect the CEMA rating system.

Jan 1, 2002

By Jim Avraamides

The properties of activated carbon which are important for gold recovery applications include activity, capacity, wear resistance, particle size distribution and bulk density. There are experimental difficulties in attempting to simulate the plant environment in the laboratory in order to measure the above properties. However, standard tests can be set up to compare the characteristics of different carbons and to assist in monitoring the performance of carbon in CIP operations. These laboratory tests are critically evaluated and data are presented on the performance of carbon from a number of CIP plants.

Jan 1, 1989

By Paolo Massacci, Marco de Nardis

SPL (Spent Pot Linings) are hazardous waste. The described work seeks to identify simple and inexpensive processes for recovering the recyclable materials and thereby both reduce the volume to be handed to the dumps and produce a waste that belongs to a less dangerous class. For this purpose a study was conducted to characterise the structure of the cell and the refilling elements at the end of the Aluminum process. The properties of the material that make up the SPLs were determined in order to apply the related selection procedures. The study permitted the design of treatment process able to reduce the negative environment impact of the aluminum production cycle.

Jan 1, 1995

By T. Valentine

The SX-EW operation at Morenci includes three electrowinning tankhouses. Stainless cathode blanks require the use of insulating plastic edge strips, which typically have a service life of 1-2 years, therefore, regular replacement of edge strips is a fact of life in tankhouse operations. The largest tankhouse, Central, converted from starter sheets to stainless steel cathode blanks in 1999. During the first year of stainless blank operation at Central Tankhouse, the initial installation edge strips started failing at accelerated rates and there was a sudden need to replace edge strips and repair between 350 and 400 cathode blanks per day. This paper details the design and building of cathode repair shops at the Morenci tankhouses, including choice of equipment and layout design. The objective was to increase efficiency through the use of cathode handling equipment and flow of material.

Jan 1, 2002