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By R. R. Klimpel

This paper demonstrates, using the results of an unusually complete industrial test sequence, what the various interactions are between grind size, collector dosage, and frother type. While particle size is universally acknowledged to be important in optimizing industrial copper sulfide rougher flotation circuits, many of the various interactions that do occur at the industrial level with particle size are still being identified and/or quantified. This study also presents, in a consistent manner, the changes in flotation kinetics that occur as a function of particle size, in a typical industrial circuit along with some insights as to how flotation operators can optimize rougher circuit performance.

Jan 1, 1993

By T. Lamond, J. O. Costello

Marble is a preferred surfacing material in up-scale buildings. Its use increased in the 1870's with rising national wealth and declined in the 1950's when synthetic materials for these applications were developed. Natural marble is now limited to high-end domestic and commercial structures. Cultured marble is a paste of white marble dust and polyester resin cured in molds yielding fixtures of specific finished dimensions. Dyes incorporated at different stages in the mixing cycle mimic shades and veining of natural marble. This paper discusses the filler requirements for cultured marble production and reviews new techniques to cut and finish natural marble.

Jan 1, 1999

By Cory Dippold, Michael Mett, Jérôme Steinkühler, Kristi Latimer

For decades, tunnels of all types have been a significant part of our infrastructure. In particular, water tunnels carry millions of gallons of fresh water every day to major metropolitan areas and surrounding communities. As a critical piece of public health infrastructure, it is important to inspect the condition of these tunnels regularly to ensure reliable and continuous operation. A specific challenge with water infrastructure is that it’s often difficult or impossible to shut down the system for long periods of time to perform the needed inspections. The latest method of tunnel condition assessment is the use of hybrid reality 3-D scan data. Photogrammetric and LiDAR based 3-D data ensure a reliable and objective view of tunnel conditions. The data can be used to support a detailed digital inspection including the compilation of databases that consist of a wide variety of deficiencies such as cracks and spalls within the structure. Mott MacDonald, a design engineer company worked closely with Dibit, used a 360-degree scanning system to collect high-resolution photogrammetric and LiDAR data on a recent project involving a water tunnel. The allows for full 360-degree coverage of the tunnel surface including a water covered invert. It operates at walking speed and ensures a fast and reliable data acquisition which can reduce the time of tunnel shutdowns. Several allocated inspection weeks can reduce to few days, with the final work product being a higher quality and more complete deliverable than traditional inspection methods would have provided. The true-color 3D-model has a photo resolution of 1 × 1 mm (0.039 × 0.039 inches) which makes cracks visible with a width of down to 0.3 mm (0.011 inches). The assessment of water tunnels, its technical challenges and the results of the 3D-tunnel inspection case study are illustrated and described in this publication.

Dec 1, 2022

By A. F. Grandt

What is prime farmland? Can such land, once it has been strip-mined for coal, be restored so that it will produce corn, soybeans, wheat, and alfalfa? What methods or practices are necessary to bring about restoration within a reasonable time so that crop yields will be equivalent to or higher than those of unmined prime farmland under high levels of management? These questions concerned land use researchers in Illinois as early as 1948 when the Illinois Agricultural Experiment Station experimented with growing cultivated crops on strip-mined land in St. Clair County (1). This research was done almost 30 years before requirements of Public Law 95-87 were passed by the United States Congress and signed August 3, 1977.

Jan 1, 1980

By III Sadler

Processing bauxite and clay ores to reduce Iron content to levels low enough for the ores to be suitable raw materials for such products as refractories and abrasives has long been regarded as a diffi9ult problem. Standard magnetic separation processing of the untreated ore has been attempted by previous investigators with only limited success due to the finely divided state and weak magnetic susceptibility of the iron minerals (hematite, geothite, etc.) present in these ores. The new process described in this paper consists of calcining the finely crushed ore at 500 to 800 C and then reducing (with hydrogen, carbon monoxide, etc.) the iron oxides present to magnetite or elemental Iron. The magnetic susceptibility of iron in these forms is enhanced 40-to 100-fold over that of hematitie and is readily removed by simple magnetic separation. Starting with a 2.7% Fe20s Alabama bauxite ore, a 1.5% Fe20s product was produced in one pass through a Davis tube magnetic separator with 95 + % recovery of the iron-free bauxite fraction and a 20% Fe20a magnetic product. These findings suggest that with the addition of light calcination, reduction and magnetic separation steps to the conventional refractory grain production process, the large U.S. reserves of high-iron bauxites could be used.

Jan 1, 1990

By W. G. Lawrence

The rapid development of science and technology in Russia has been the result of well laid plans since 1918. At that time the Institute of Silicates was established is Moscow and later the establishment of similar more specialized institutes for the study of cement, glass, refractories, construction ceramics, electrical ceramics, building materials and asbestos provided the necessary research facilities for studies related to all types of ceramic inorganic materials. The' Institute of Ceramics and the Institute of Silicate Chemistry, Academy of Sciences, USSR, were founded in Leningrad. The work now going on in these various research' institutes covers every branch of silicate science and ceramics The impetus behind such establishment of special¬ized laboratories is no doubt due to the 5-year plans and the necessity of improving the scientific knowledge regarding the materials being used and the products being manufactured.

Jan 1, 1960

By D. M. Walters, C. M. van der Vyver, L. J. deVulliers

The occurrence of underground fires in narrow tabular ore- bodies where high density timber support is used is a dangerous and disruptive occurrence. The containment and extinguishing of the fire remains a very important consideration in reducing not only the loss in production time but also in limiting the extent of the area damaged by the fire. Mindful of this, Gold Fields have adopted and developed the inert gas generator system from its origins in Poland for use in Group precious metal mines. The system generates an oxygen- deficient atmosphere which is introduced in the fire area after this has been sealed. A number of problems had to be overcome to operate this system successfully within the infrastructure of these mines. Of particular significance is the operation of a jet engine, the prime component of the system, at air pressures encountered below sea level. The modifications have been found to be satisfactory to the point where, since 1992, ten underground fires have been extinguished using this system. Invariably, the areas affected by these fires were extensive (over 1 000 000 m3) and required continuous operation of these units over extended periods of time (in some cases in excess of 400 hours).

Jan 1, 1997

By D. R. Spears

Conventional round tank thickeners have been widely used in the mining industry for many years. The mining industry was well satisfied with the ability of conventional thickeners to improve minerals beneficiation operations. However, development of improved flocculants (the polyacrylamides) made possible much more rapid settling rates, since polyacrylamides produce large flocs rapidly (unlike starch or inorganics). Traditionally considered to be a slow operation if maximum underflow density was achieved, and therefore there was some justification for the expense. Thickeners required large volumes to permit sufficient time for settling. The oversize not considered a drawback but the initial capital cost was. In high rate thickeners, a bed of thickened material is allowed to build around the feedwell, even above the bottom of the feedwell. The slurry is fed directly into the bed at a velocity that allows the material to be evenly dispersed over the thickener area This more efficient use of settling area allows a higher solids throughput per unit surface area (rise rate). In this paper, high rate thickener rise rates and polymer consumption are compared.

Jan 1, 1998

By Peter J. Conroy

Introduction Most subsidence monitoring to date has been surface monitoring to develop empirical relationships of the magnitude and extent of subsidence effects. Federal regulations are forcing a better understanding of subsidence. Empirical methods of subsidence prediction may not be adequate, since the empirical relationships may not be valid between or even within coal fields. A better understanding of the mechanics of subsidence is required in order to develop and verify analytical models. This paper presents some of the results of surface and underground monitoring in longwall faces of a coal mine. The seam thickness in these mines ranges from 5 feet to 6 feet at depths of 600 to 1100 feet.

Jan 1, 1982

By S. R. Bryan, J. D. Stephens, D. R. Rothbard

The distributions of gold and associated elements in mineral grains from a pyritic gold ore were studied by optical microscopy, and by SEM and SIMS imagery. Products studied were a sulfide flotation concentrate, a calcined sulfide concentrate, a cyanide leached calcine, and a cyanide leached pressure oxidation residue. Individual pyrite grains are compositionally zoned and solid solution gold occurs in some, but not all zones. Most of the gold in calcined products is present as metallic coalesced grains that are smaller than 100 angstroms. Gold lost into cyanide leached residues from the calcines tends to be in “semi-dense” grains that cannot be distinguished from gold-free grains except by SIMS analysis. The gold in cyanide leached pressure oxidation residues occurs as solid solution gold in unoxidized pyrite remnants.

Jan 1, 1990

By T. Harrison

Surface coal mines in West Virginia are receiving stringent NPDES discharge limits for total recoverable selenium. With limits in the low parts-per-billion range, selection and implementation of proper sample collection and analytical methods are imperative for quality assurance and control and for consistency in results. Given the typical oxidized form of selenium in the water, the low limits and the large and variable flow rates from the watersheds, end-of-pipe treatment is difficult and cost-prohibitive to implement. Discharge locations in the remote and steep terrain exacerbate the problem. To evaluate options for end-of-pipe treatment at a Patriot Coal Corporation surface mining operation in West Virginia, CH2M HILL performed wastewater characterization for a range of key constituents and selenium species at three outfalls for selection and preliminary sizing of appropriate treatment processes. A preliminary evaluation of base and wet-weather flows was done to understand flow variability considerations for discharges. A conceptual evaluation of technologies to treat selenium to permitted levels was conducted in con-junction with order-of-magnitude life-cycle cost estimates.

Jan 1, 2010

By Clarence O. Babcock

A simple robust rock bolt load gage was tested in the laboratory to define its characteristic behavior and to obtain a measure of its performance. The gage uses three vibrating wire sensors crimped 120 degrees apart into the outer surface of a hollow cylindrical steel tube. The resonant frequencies of the wires change as the gage is loaded. This change is read with a Creare meter developed for the Bureau on a previous contract to read borehole stress gage results. A statistical analysis of data obtained defines the variables influencing results. A U. S. patent (3,914,992) assigned by the author to the Department of the Interior was granted October 28, 1975.

Jan 1, 1976

By Edward F. Divers, J. Drew Potts

Powered dust-filtering helmets (dust helmets) have become increasingly prevalent in the underground mine environment in recent years. Many longwall operations use dust helmets to reduce the respirable dust exposures of miners required to work downwind of crusher, roof support and shearer operations. While continuous mining sections are usually less dusty, use of diesel equipment represents a new potential health problem. The U.S. Bureau of Mines recently conducted a study to determine the efficiency of a dust helmet on diesel-size particulate. Two underground evaluations were conducted on continuous mining sections that were using diesel haulage vehicles. Model No. AH21 Racal airstream helmets equipped with AS22-3 prefilters, AS23-3 main filters and AS60476 tyvek full-face seals were tested. Helmets were placed on mannequin heads and mounted in the ram car cabs. Andersen Model 298 (eight-stage) personal cascade impactors were used to sample air inside and outside of the helmet. Impactor stages 8 and the final filters were analyzed to determine submicrometer (0 - 0.93 µm) particle concentrations. Results from this study showed that the dust helmet was 94% (± 3% at 95% confidence level) efficient on submicrometer particles. Typically, very little coal dust is observed in the submicrometer size range, therefore, these particles were assumed to be from diesel exhaust. Results from this study indicate that proper use of the dust helmet on continuous mining sections that are using diesel haulage vehicles may be beneficial to the health of miners.

Jan 1, 1991

By J. A. Brierley, Arpad E. Torma, Victor C. Storhok, C. L. Brierley, Batric Pesic

Chemical and electrochemical studies were performed during bioleaching of cobaltite concentrate with Thiobacillus ferrooxidans. The two principal minerals present in the concentrate were pyrite and cobaltite (CoAsS). During chemical studies, the effect of pH on dissolution rates was examined under uncontrolled and pH-controlled conditions. It was found that in the pH range 1.5-3.0 there was no pH effect if the initial pH was not controlled (maintained). When the initial pH was controlled, the leaching of Co, As, and Fe depended strongly on pH. Electrochemical studies were performed by using cyclic voltammetry and constant potential techniques. A sequential reaction mechanism was proposed for dissolution of cobaltite.

Jan 1, 1993

By J. A. Organiscak

Data on dust-control practices, mining conditions and occupational exposures were gathered for approximately 80 underground continuous mining units. Despite silica contents on dust samples in excess of 5%, nearly forty units successfully maintained silica concentrations at or below 100 µg/m3 on a majority of occupational dust samples, while the remainder had difficulty maintaining this level. These two sample sets were termed Group A operations and Group B operations, respectively. This data was compared to identify causes of high occupational silica dust exposures. Analyses of dust-control parameters and geologies revealed only minor differences between these two groups. However, subsequent comparisons of face ventilation design showed considerable differences in silica exposure and silica content between Group A and Group B at the continuous mining machine and roof bolter operator occupations. These differences were minimal when using exhaust curtain ventilation with a dust scrubber. This face ventilation system can benefit operations having difficulty controlling silica dust exposure and silica dust content. The collected data also showed that occupational samples from Group B operations possessed generally higher silica exposures and silica content than similar samples from Group A. The single head roof bolter (helper) possessed among the highest silica exposures and silica contents in both groups.

Jan 1, 2002

By Arthur E. Lewis

A contained nuclear explosion is proposed to produce a chimney of broken ore well below the water table. After the chimney is filled with water and reaches hydrostatic equilibrium, oxygen, under pressure, is introduced near the bottom of the mass of broken rock. The increase in solubility of oxygen at high hydrostatic pressure is sufficient to initiate the oxidation of the primary sulfides: chalcopyrite and pyrite. The oxidation and dissolution of these sulfides produces enough heat to increase the temperature of the ore and water in the chimney as much as 1000 to 150°C. The rate of dissolution of chalcopyrite becomes so rapid under these conditions that the rate of recovery is no longer limited by the rate of chalcopyrite dissolution, but by the degree of exposure and other factors. Means of solution control and distribution of oxygen in the chimney have been examined in some detail. A calculational model utilizing experimentally determined solubility rates is utilized to estimate the temperature rise in the chimney and the rate of copper recovery as a function of initial temperature, sulfide content of ore, size of sulfide particles, and fraction of sulfide exposed to solution.

Jan 1, 1972

By A. Ang-Ug, L. Gurieff

"The Phu Kham Cu-Au mine in Laos is owned and operated by Phu Bia Mining Limited. The deposit is a complex and low grade Cu-Au porphyry ore. The rougher feed has a particle size distribution of 80% passing 110 µm, and the rougher concentrate is reground for cleaning to 80% passing 25 µm. The Cu losses in the cleaning circuit are primarily in the <12 µm fraction. A randomised paired ON-OFF test of magnetic conditioning in one of the two parallel cleaner 1 circuits was undertaken. The results showed that with magnetic conditioning there was approximately a 10% reduction in the <12 µm Cu distribution in the cleaner 1 tail to a 98% level of confidence. The Cu distribution in the <12µm fraction is a less variable measure of changes in the <12µm Cu recovery, therefore, this was used to evaluate the impact of magnetic conditioning. Subsequently, magnetic conditioning was installed in both cleaner 1 circuits and the plant results monitored after this installation. Comparing the plant results immediately before and after this installation showed that there was a 20% reduction in <12µm Cu losses to the cleaner tail. INTRODUCTION The Cu-Au, Phu Kham Mine (PKM) is located within PanAust's Phu Bia Mining Contract Area in Laos, approximately 140 kilometres from the capital city, Vientiane. PKM is PanAust's flagship operation and the significant cash flow generated by PKM has supported PanAust’s growth, while contributing to a strong balance sheet. PKM comprises an open-pit mine and a conventional milling and flotation operation that produces and exports a Cu and precious metals concentrate. The concentrate contains around 23% Cu, 6 ppm Au and up to 35 ppm silver. Process Overview The PKM deposit consists of complex heterogeneous mineralogy horizons of Cu-Au stockwork and skarn mineralisation. It contains areas of soft-leached zones, overlying transition zones and supergene chalcocite dominant secondary Cu mineralisation and clay-rich gangue. Areas of high As and Zn also pose a challenge in treating the highly variable ore. In addition, hardness of the ore increases with deposit depth. The ROM is hauled to a primary gyratory crusher to produce a coarse ore stockpile with size distribution suitable for the 13 MW semi-autogenous mill. The SAG product feeds two parallel ball mills each equipped with a cyclone cluster producing a product particle size distribution of 80% passing 110 µm. The conventional flotation circuit consists of two parallel rougher banks. The rougher concentrates feed the regrind cyclone where the underflow is split and reports to two parallel, 3MW, M10000 IsaMills. The regrind mill discharge combines with the regrind cyclone overflow with a product particle size distribution 80% passing 25 µm and reports to the Jameson cell."

Jan 1, 2018

By Brian W. Hester

Ore was first discovered at the Kidd Creek mine site during the first few days of December 1963 when a diamond drill hole there cut sulfide mineralization. This event marked the end of the search started 11 years earlier with the conception of a geological idea. Economic forces provided the stimulus needed for the application of this idea but other-events, and legal considerations, also played arole in delaying the ultimate discovery. The location of Kidd Creek is shown in Fig. 1. Management of the then Texas Gulf Sulphur Co. had become concerned in 1951 at the company&apos;s declining reserves of native sulfur in Texas. This problem was to be alleviated by new discoveries and development of methods to recover sulfur from sour gas. At the time, however, the solution appeared to lie in the recovery of sulfur from pyritic ores. Canada was chosen as the best country in which to find these ores. Walter Holyk was hired in 1951 to conduct the search. By 1952, he was working in the area near Sherbrooke, Quebec, known as the "Eastern Townships" where mineralization consisting of base metal sulfides in volcanic rocks has long been known. His observations here led him to the then revolutionary conclusion that such mineralization could have formed as part of the volcanic process and not, as was generally supposed at the time, by replacement. On learning of the discovery of similar mineralization near Bathurst, NB, he moved there in the spring of 1953. He was able to utilize his new concept and found the Half-Mile Lake sulfide deposit.

Jan 1, 1991

By D. Van Orden, Y. Kamiya, R. Lee, E. Ilgren

Crocidolite is a well-known causative agent for mesothelioma. However, studies have shown that the pathogenicity of the fiber from different mines varies considerably and it has been postulated the parameter that appears most likely to account for this variation is fiber width although this has never been formally confirmed. To date, crocidolite appears to be the only asbestos mineral for which an epidemiological study comparing the risk of mesothelioma in a population exposed to ‘thin’ fibers with another exposed to ‘thick’ fibers of the same species may be carried out. Finnish anthophyllite, South African amosite, and African Transvaal crocidolite can also be classified as thick fibers, and there is a paucity of mesotheliomas in populations exposed to them compared to those exposed to thin Cape crocidolite. No thin occurrences of these minerals are known. Our previous study looked at crocidolite from several sources. The present study considers the amphibole anthophyllite found in many places in the world. This mineral, regardless of source, does not show the same variation in fiber width found with crocidolite from different areas. All anthophyllite fibers that have been mined may be classified as thick and populations exposed show very low levels of mesothelioma. We suggest the most likely explanation is related to the fiber width distribution and a concomitant reduction in the ‘Stanton fiber size’ fraction.

Jan 1, 2012

By Michael J. Mankosa

Increased emphasis has been placed on recycling consumer and industrial waste products. This trend has created a new industry that is focused on recovery/ separation of byproducts from waste material. As a result, interest has increased in the development of separation systems designed for the recycling industry. Much work has been done in this area. However, existing techniques developed for minerals beneficiation are often ignored. An example of is the foundry industry. There are currently more than 3,000 foundries in operation throughout the United States. Each consumes between 9 and 900 t/d (10 and 1,000 stpd) of sand for mold production. Either silica, chromite or zircon is, used in various combinations with chemical or clay binders. After casting, the sands are typically discarded into a landfill. This practice has become an environmental concern, especially the disposal of chromite and zircon. Silica sand is not environmentally sensitive. But it is used in greater abundance (6 to 7 Mt/a or 6.6 to 7.7 million stpy)and thus has prohibitive haulage and landfill costs. Current technology for sand reclamation involves thermal treatment to remove residual binders followed by dry mechanical attritioning (Leidel, 1993; Klein, 1994). This approach results in high losses due to fines generation and high costs associated with thermal treatment. As a result, this approach has shown only limited success. Stringent regulations are also affecting the disposal of secondary materials, such as plastics and metals. This is particularly true for the ferrous and nonferrous scrap metal industry. It plays a major role in industrial recycling of steel, aluminum and copper. Applications such as wire recycling present challenging problems since a hazardous byproduct (plastic insulation) is generated by the recycling.

Jan 1, 1997