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By Y. B. He

The effect of the stability and rheological properties of magnetite dense medium on the separation performance of a 6" dense medium cyclone (DMC) is studied with the use of fine density tracers. The tests in which different size fractions of magnetite are used to prepare the dense media reveal that at low medium densities (<1.5 s.g.), the best separation is achieved when using the magnetite with intermediate particle sizes (du3.2=18 11m). At medium densities above 1.5 s.g., however, it is beneficial to use coarser magnetite. With the fine magnetite dense medium, an increase in medium density results in a decrease in separation efficiency. With the coarse magnetite, an opposite trend is observed; the separation efficiency is improved with increasing medium density. An accurate cutpoint control is critical in gravity separation. The cutpoint shift for coarse feed particles is found to decrease with increasing medium stability (density). It assumes values close to zero in a highly stable fine dense medium. When the size of the treated particles is small (<0.5 mm), the cutpoint shift is mainly determined by medium rheology. With increasing medium density, a continuous increase in cutpoint shift is observed.

Jan 1, 1993

By Jey K. Jeyapalan

A characteristic common to most tailings dam failures caused by earthquakes or excessive rain storm is that the tailings tend to liquefy and flow for substantial distances as a viscous fluid, with the potential for extensive damage to property and life. Failures of El Cobre, Chile (1965), Mochikoshi, Japan (1978), Aberfan, Wales (19661, Buffalo Creek, West Virginia (1972) are examples of such catastrophic incidents. In these four incidents more than 400 lives were lost, and the loss of property was approximately $200 million. In order to be able to assess the potential for damage in case of such a failure, it is necessary to predict the possible extent of flow slide movement. This paper discusses simple procedures for performing such analyses. Also, in order to illustrate the use of these analysis procedures in tailings dam design, two case histories are analyzed.

Jan 1, 1982

By F. W. Schweitzer

The trend toward development of large low grade ore bodies has accelerated in recent years. It has been estimated within the copper industry that "porphyry" type deposits will provide the bulk of copper production during the next 30 years. It is further estimated that in these deposits the average ore grade by the year 2000 will be 0.25% copper (1). Many of the new porphyry copper discoveries are of such extremely low grade that they are particularly sensitive to small fluctuations in cost variables and copper prices. Because haulage constitutes a major item of surface mining expense, the capability to transport large tonnages of material at increasingly lower unit costs is vital to the profitable operation of many of these mines. High capacity conveyor belts appear to have considerable promise in this area. The heaviest use of high tonnage conveyors has been in the brown coal industry in Germany. In the past 20 years several such installations have proven successful. In addition to the German installations, several other successful systems have been put into operation. Some examples are: The Oroville Dam project in the United States; the tar sand operation in Northwest Canada; the pre-mine stripping and mining of the Twin Buttes Mine in the United States; the Kursk Magnetite &apos;dine in the U.S.S.R.; and the Nchanga Copper Mine in Zambia. Most of the systems mentioned are handling alluvial material consisting mainly of fines. The noteworthy point regarding these installations is their high continuous capacity. One of the largest lignite mines in the world is at Fortuna, Germany, where over 15,700 tons (15,250mt) per hour of overburden is transported on an 87 inch (221cm) wide belt running, at over 1000 feet (305m) per minute.(2). Another example is a 20,000 ton (18,150mt) per hour system for loading iron ore into barges on the Great Lakes (3).

Jan 1, 1976

By Edward J. McNamara

Sulphur as an element has been used for centuries. The technique of storing, handling and transporting it in its various forms has changed through the years. Freeport Sulphur Company, a division of Freeport Minerals Company, has produced sulphur since 1912. The first storing and transporting of this product as a liquid began in 1947. Significant environmental problems occurred in the handling of solid sulphur in the late fifties and early sixties. Since the sulphur WAS produced in the liquid form and the major customers used it in the liquid form, it became obvious that a liquid transportation system was the solution. The liquid sulphur delivery eliminated the dusty and hazardous handling problems and the contamination of the sulphur by dirt, acid, moisture and other materials. The remelting by the customer to use the sulphur is thusly eliminated with a savings in energy. In addition, this change in the mode of handling permitted a broad development of new sulphur mines in the marshy coastal area of Louisiana and offshore in the Gulf of Mexico.

Jan 1, 1978

By O. P. Burghardt

Blast furnaces of high specific throughput capacities producing 10,000 tpd of pig iron or even more, require burden materials which, because of their chemical, physical and metallurgical properties, guarantee such high performances. Meanwhile, it should be generally accepted that for evaluating the quality of iron ore pellets, it is not sufficient to know the chemical analysis and the physical properties, i.e. grain size distribution, cold compression strength and abrasion of the fired pellets. It is indispensable to determine the metallurgical properties indicated by swelling, reduction-softening under load and reducibility, as well as grain disintegration in the low-temperature range in the beginning of reduction. By introducing new test methods, and in the face of the need to meet more strict requirements, pellet producers are being confronted with steadily increasing tasks and problems which require a deepening of our knowledge of the ways and means of making high-quality iron ore pellets.

Jan 1, 1975

By Akira Ishikuro, Masamichi Shintaku, Futoshi Kusumoto, Takeshi Kudo

"The Bankei-Kitanosawa tunnel that is located in Sapporo, Hokkaido, Japan includes a 450m long section near the arrival point where mudstone which can liquate out natural hazardous materials such as arsenic and selenium exceeding the tolerance stipulated by country as well as weathered mudstone and unconsolidated sedimentary rocks with small overburden and the competence factor less than 1.0 are present. The mucks containing hazardous materials were disposed into the waterproof branch tunnels created from the inside of the main tunnel. The full face early ring closure method was employed to ensure the stability of the tunnel in the low strength rock masses having no stand-up time. As a result, the waterproof tunnels branching off the main tunnel can manage water tightness so as to ensure safety and relief against environmental risks of the hazardous materials. It is also demonstrated that the full face early ring closure method enable construction of the tunnel with a small overburden in the low strength rock masses. INTRODUCTION The Bankei-Kitanosawa tunnel includes a 450m long section near the arrival point where mudstone which can liquate out natural hazardous materials such as arsenic and selenium exceeding the tolerance stipulated by country as well as weathered mudstone and unconsolidated sedimentary rocks with small overburden and the competence factor less than 1.0 are present. In order to overcome the restrictions, the hazardous materials were designed to be disposed into large cross section waterproof tunnels which were newly designed and constructed in high strength and hazardous material free Andesite. The lining for the tunnels was composed of with shotcrete. In addition, full face early ring closure (Sato et al., 2013) was employed to stabilize the tunnel so as to enable safe tunnel excavation in low strength rock masses where a ground arch is deemed unachievable. This paper presents the safe disposal method of mucks which are likely to liquate out natural hazardous materials as well as the full face early ring closure method and its mechanical characteristics."

Jan 1, 2016

By D. M. Abbott

The problem with best practices occurs when they do not work. This happens when the seldom-stated assumptions underlying the practice are not met. This paper provides some examples for the mining industry: (1) when core splitting is inappropriate, (2) when the use of fire assays for placer samples is inappropriate, and (3) when high-grading may be acceptable. Geologic conclusions are, in the final analysis, expressions of judgment predicated upon knowledge and experience. A geologic conclusion, however, purports to be more than an arbitrary determination—it is reached as a consequence of method. No specific method is required, but the method used must be an orthodox method, in accordance with orthodox definition of terms, and the one best adapted to the dealing with the questions asked about the property in question. Whether the so-called “best practice” is really applicable to the job at hand must be decided on the basis of professional scientific judgment. When one decides to deviate from a published “best practice” for sound scientific reasons, describe in detail in the report what the so-called “best practice” is, why it was inappropriate for the project, and why the method used was better. If one becomes aware that a “best practice” is being proposed, actively urge those proposing it to include in its description the underlying assumptions that must be met in order for the “best practice” to be valid.

Jan 1, 2014

By Peter Amelunxen, Kain Nugent, Brandon Akerstrom, Willem Duyvesteyn, Todd Harvey

In 2024, Capstone Copper Corp commissioned a new sulfide flotation plant at Mantoverde in the Atacama region of Chile to process copper ore at a design rate of 32,000tpd. The pyrite associated with the copper ore body contains cobalt in solid solution, with Co replacing Fe in the pyrite matrix. As per the existing sulfide flotation flowsheet most of the pyrite is depressed and sent to tailings via the cleaner scavenger tail stream. A new project considers the recovery of the pyrite from the cleaner-scavenger tails via froth flotation to produce a cobaltiferous pyrite concentrate, which is then leached via the existing dynamic copper leach pad to oxidize the pyrite and dissolve the cobalt. The cobalt is recovered from the solution by treating a bleed stream of copper SX raffinate through a continuous, counter-current ion exchange (CCIX) facility. This approach to by-production of cobalt confers numerous benefits, including reduced costs compared with alternative cobalt recovery processes, reduced acid consumption in the heap leach, increased copper production, and reduced acid mine drainage potential due to the removal of pyrite from the mill tailings.

Feb 1, 2025

By A. K. Clarke

In any treatment process that requires a coarse feed material to be reduced to a fine size by crushing and/or grinding it must be determined whether a wet or dry comminution system should be utilized. All factors must be evaluated in reaching the decision. Among these factors are: 1) Ecology and Plant Environment: Unfortunately in many instances the decision on wet or dry is based on prejudice resulting from an unnecessary fear of dust. The writers submit that this fear, although once justified, is no longer valid because technology and equipment is now available to collect dust to meet any standard. When dry grinding is used it is very often possible to discard a portion of the waste product in a dry state. This will decrease the size of the tailing pond required. As pollution control standards increase it becomes increasingly difficult to clean up water from tailing ponds. 2) Operating Costs: Steel wear is often five or more times greater in wet grinding than in dry grinding. This is mainly due to corrosion. The evaluation of the economics of dry grinding must of course include the air system and dust collection; similarly in a wet grinding plant related pumping and material handling costs should be included. Pumping costs are often overlooked. This assumes water is made to flow for nothing. Pumping can account for 20 percent of the power consumption in the grinding plant. Large scale comparative tests were conducted in a wet and dry commercial plant in 1970. The same ore was used for both tests. With all factors included in both plants the dry system showed lower horsepower per ton.

Jan 1, 1971

By David Lynn Passmore

The reliability of mine operators reports to the Health and Safety Analysis Center of the U.S. Deparetment of Labor of days lost from work by injured miners is .267.

Jan 1, 1985

By Paul Soros

Lord Robens, Chairman of the National Coal Board of England announced recently to the world press plans for construction of the largest bulk terminal in Western Europe. This should result in annual freight savings of 22.4 million dollars and between 150 and 190 million dollars of new export business. These are rather substantial amounts for any mining enterprise. Or to put it another way, opportunities to make substantial savings in the delivered price of a highly competitive commodity such as coal are few and far between. One area where such opportunities still exist is in the economical; movement of bulk materials between producer and consumer.

Jan 1, 1966

By D. L. Langhans

Platinum-group metal (PGM) converter matte from the Stillwater Complex, MT, was subjected to chemical and biological leaching in an effort to upgrade the matte by decreasing the Cu and Ni content. Copper and NL extractions were optimized in a two-stage chemical leach. Atmospheric pressure sulfuric acid leaching removed over 90 pct of the Ni and Fe in the first stage, while 95 to 98 pct of the Cu was removed is the second stage using an acidified cupric chloride leach. This two-stage leach, followed by an elemental sulfur removal step, decreased the weight of the matte by 90 pct. The combined Cu and Ni content was reduced from 65 pct to less than 20 pct, while the PGM content was increased from less than 2 pct to 26 pct. Biological oxidation using Thiobacillus ferrooxidans also proved to be an effective method for removing Cu and Ni. Over 90 pct of the sulfide was oxidized and 99 pct of the Cu and Ni were solubilized, leading to a 60 pct reduction of sample mass during the 17 week bio-oxidation of the Stillwater converter matte. The final residue, after removal of jarosite that accumulated during bio-oxidation, contained less than 3 pct combined Cu and Ni and 6 pct MM.

Jan 1, 1993

By L. Yuan, J. Soles, W. Tang, R. Thomas

Lithium-ion battery pack fires pose great hazards to the safety and health of miners. A detailed experimental study has been conducted at the National Institute for Occupational Safety and Health (NIOSH) Pittsburgh Mining Research Division (PMRD) to investigate the effectiveness of different fire suppression systems on Li-ion battery pack fire extinguishment. Tests were conducted in a well-ventilated container. Two sizes of battery packs (12V, 24V) were heated by heater strips to trigger thermal runaway and fire. Water mist with different flow rates, ABC powder, type D dry chemical, and water mist with F500 additives were used as the fire suppression agents. Multiple thermocouples were installed on the battery packs to measure the temperature evolution during the tests. The results indicated that the water mist with F500 additives is the most effective suppressant among the agents tested. Dry chemicals, however, do quench the fire for a moment, but cannot prevent re-ignition of the battery since they do not provide enough cooling. The findings of this paper can be used to develop safer battery fire suppression techniques in mining environments.

Feb 1, 2023

By D. R. Nagaraj

Based on our finding that commercial copper chelating solvent extractants such as LIX65N® and LIX63® are excellent collectors for copper minerals, a detailed study was made using several water-soluble chelating agents belonging to the class of aromatic hydroxyoximes and having a gradual structural variation. A basic study of the system salicylaldoxime-tenorite was also carried out. Microflotation tests as a function of concentration of oxime, pH, addition of copper etc., using oxidic copper minerals such as chrysocolla and tenorite, and batch laboratory flotation tests using synthetic mixtures of quartz and oxidic copper minerals were carried out. The studies were aimed at an understanding of the collector function of the hydroxyoximes and of the general flotation behavior in these systems, in addition to studying the structural aspects of oximes vis-a-vis flotation. The results have demonstrated that all of the hydroxyoximes studied here have comparable collector property, and in all cases the oxime was found to be partitioned between the mineral surface and the copper in the bulk aqueous phase in the form of a bulk copper chelate. The occurrence of the latter could be accounted for by the formation in the bulk phase of a chelate between oxime and copper released from the mineral and/or by the detachment of the surface chelate. The role of surface and bulk chelates in flotation is discussed based on the results of partitioning of chelating agent into bulk and surface chelates in the system salicylaldoximetenorite. The effect of substitution of CH2 groups or benzene ring in the chelating agent molecule on its collector property is also discussed, in addition to the finding that only the anti-isomer has the ability to collect.

Jan 1, 1979

By Harvey P. Knudsen

Case studies are presented in this paper to illustrate the usefulness and applicability of using conditional simulation in under- ground coal mine planning. Conditional simulation is a technique developed in the last five years that allows the building of a simulated ore body (or coal deposit) model. Construction and validation of the simulated model is described in order to show how well the model reproduces the essential characteristics of the deposit. In the model, the thickness, ash, and sulfur content are known everywhere in the deposit and each variable has the same mean, variance, and spatial variability (variogram) as that variable has in the real deposit. Use of the simulated deposit in the design of drilling strategy for long range mine planning is demonstrated in me case study. Determining the potential of short term production scheduling to reduce the fluctuations of sulfur in run of mine coal is described in the second case study.

Jan 1, 1980

By Klaus Schönert

In the analysis of comminution processes, it is necessary to have a detailed knowledge of such sub-processes as: (i) The transportation of the particles to the zone where they are stressed, (ii) The stressing of the particles to a level high enough for breakage, (iii) The removal of the fragments that are smaller than the limit size from the grinding zone, and (iv) The prevention of agglomeration of the fine fragments. The breakage phenomena of particles is the most difficult sub-process to understand. It can be understood only by applying the principles of fracture physics to obtain information about the stress-strain field in particles which are loaded either by compression or by impact, and by using this theoretical knowledge to interpret experimental results obtained from single particle crushing studies. It is not only of academic interest to know how a particle breaks, but also it is important for practical applications because it provides a basis for evaluating both the direction and limitation for any potential comminution improvement.

Jan 1, 1971

By John E. Tilton

Mining is one of the oldest human activities. It goes back at least to the Bronze Age and possibly even the Stone Age. The Romans mined copper in Spain and tin in England some two thousand years ago. The writings of Agricola in the 16th century show that mining was important in the Middle Ages. Today we mine more mineral commodities in greater tonnages than ever before. This long and fascinating history closely tied with the economic development of the human race is one of the charms of the mining industry. It also, unfortunately, gives rise to some widespread misconceptions.

Jan 1, 1997

By S. Makni, R. E. McIvor

Grate discharges historically outnumbered the overflow type of industrial wet ball mills. However, overflow discharge mills now strongly dominate. In order to understand their comparative advantages and disadvantages, Corem carried out a broad review of this topic. Where the data made it possible, the Functional Performance Equation was used to separate circuit classification from mill grinding effects. Batch tests were conducted in a torque-metered mill at different slurry levels. This paper presents the outcome of these investigations, which is a very strong case for the industry to once again consider grate discharges.

Feb 1, 2023

By Mike Perkins

The Summitville Au-Ag-Cu district in the southeastern part of the San Juan volcanic field has been a major gold producer in Colorado. Mineralization is hosted by the composite South Mountain quartz latite porphyry volcanic dome, which is believed to have been localized by the intersection of the northwest margin of the Platoro-Summitville caldera complex and the northwest-trending Platoro fracture zone. K-Ar age dates indicate that alteration and mineralization were nearly contemporaneous with emplacement of the dome at 23-20 m.y. ago, 6-7 m.y. after collapse of the Platoroo-Summitville caldera complex. The dome consists of at least four major phases including strongly altered quartz latite porphyry; a late-mineral, coarse-grained sanidine quartz latite porphyry; and postmineral quartz latite dikes. The dome was emplaced into intracaldera rhyodacite and andesite. Gold-silver-copper mineralization is concentrated near the top of the dome and is associated with pods, pipes and steeply dipping tabular zones of silicification and advanced argillic alteration. Alteration is zoned outwards from the center of mineralization through argillically and propylitically altered rocks, and is largely confined to the area of the dome. Trace element geochemical patterns for the deposit indicate a central zone of anomalous As-Au-Pb-Ag and low Mn within an exterior zone of anomalous Ag-Au-Pb-Hg and high Mn. The chief ore mineral is native gold which is associated with goethitic iron oxide in the oxide zone. In the sulfide zone, native gold is associated with copper sulfide-sulfosalt mineralization. A genetic model for the Summitville deposit is based on recent models of modern geothermal systems, with which it shows similarities in alteration, ore mineralogy, zoning, and structural patterns.

Jan 1, 2013

By Herman Gill, Dani Delaloye, Madelyn Rubin

The Foothill Tunnel is a remote 16-mile-long untreated drinking water tunnel in the San Francisco Public Utilities Commission’s (SFPUC) Hetch Hetchy Water and Power (HHWP) system. The 14-foot horseshoe shaped tunnel, constructed in the 1920s, is lined intermittently with concrete over approximately 53% of its length, with the balance being unlined rock. After detailed planning, in January of 2020 Mott MacDonald and HHWP staff completed a visual inspection and documented the condition of the tunnel with electronic data collection, photographs, and video with audio recording. The result was a comprehensive condition assessment that identified key areas of the tunnel to monitor.

Jun 13, 2021