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By M. Westendorf, T. Banerjee, S. Kaushik, D. Tinney

"The Copper Mountain Mine is located in Princeton British Columbia, Canada and produces 80 – 90 million pounds of copper annually, as well as gold and silver by-products. The ore processing plant has a conventional SAG/ball mill circuit with inline pebble crushing, followed by flotation. At most plants, much time is spent evaluating and optimizing the comminution and flotation circuits. The cyclones are a key contributor to the effective operation of the plant: They define the circulating load in the comminution circuit and provide the classification that ensures liberated material is passed through to flotation. If the cyclones are not performing as they should, the results are often a combination of lost recovery, grade, capacity and reduced throughput in flotation. For such an impactful unit operation, cyclones have historically been under-instrumented. Consider as well that the cyclones are typically located at the highest elevation in a plant, and it becomes clear why they often underperform. Copper Mountain Mine recognized the critical role that cyclones filled in their plant and worked to optimize their operation through the implementation of a Portage Cyclone Detection (PCD) system to identify plugging and roping incidents, Portage Pumpbox Control (PPC) to manage the flow to the cyclones, and AwaRE to control the grinding circuit. As a result, cyclones overflow stability has increased, switching out a roped or plugged cyclone now happens within seconds rather than many minutes, and both the grinding and flotation circuits perform better. INTRODUCTION Cyclones are one of the most extensively used pieces of equipment within the mineral processing industry because of their simplistic operating and maintenance philosophies. The cyclones are commonly used as classifiers within the comminution circuit to control the grinding product particle size for satisfactory performance of downstream operations. The cyclones are a key contributor to the effective operation of the plant and have a significant impact on the mineral processing plant operations. If the cyclones are not performing as they should, the results are often a combination of lost recovery, grade, capacity and reduced throughput. Similarly, an inefficient cyclone operation may also lead to low or high recirculating loads that impact the efficiency of the comminution circuit. This highlights the importance to have proper stability in cyclone operation while implementing any plant-wide optimisation strategy."

Jan 1, 2015

By R. H. Snow

Although industrial size reduction methods have an energy efficiency of only about 1 percent, methods of size reduction have not changed much for many years. One reason for slow progress has been the oversimple viewpoint that a single law should exist to relate size reduction to energy input. Modern simulation methods decompose the grinding process into a grinding rate function (selection function) and a breakage function. The breakage function is difficult to measure, and it usually requires tracers if it is determined from milling experiments. Prediction of breakage functions from basic principles is one objective of this paper. In this study we focus attention not on the gross energy input to the experiment, but on the spatial distribution of stress energy within the particle. We are led to this viewpoint by experimental observations of a few previous investigators (Bergstrom2, Rumpf3, Axelson4) and our own observations. Oka and Hiramatsu recently used their calculations of stress within particles for prediction of breakage, but again they tried to correlate the size of the fragments with the total stress energy, rather than the approach we propose. We assume that the stress energy is stored in the interior of the particle as the load is increased, until the particle breaks. We assume that each element of the particle breaks into fragments of a mean size that depends on the locally-stored stress energy. The size distribution of fragments is the computed from maps of the stress-

Jan 1, 1972

By M. B. Freeman

Acrylic polymers have been found to be effective dispersants and stabilizers in a wide variety of mineral processing applications including rheology control in concentrated slurries. This paper will describe these low molecular weight, water-soluble polymeric dispersants and provide a basis for how they function in concentrated slurries based on computer molecular modeling and applications results. Data on homopolymers as well as copolymers of acrylic acid will be presented to demonstrate the optimization of a polymeric dispersant in preparing high solids slurries of inorganic materials such as kaolin, calcium carbonate, lime, and magnesium hydroxide.

Jan 1, 1996

By Chulho C. Song, Liam Coleman

Alkaline pressure oxidation (POX) is an oxidative pre-treatment option that is commercially used for high-carbonate sulfidic gold ores. The high carbonate grades within the feed ore shifts the ideal operating pH to a basic regime. Compared with acidic POX, alkaline POX typically requires additional steam input due to a lower sulfur oxidation load and a high rate of in-situ carbon dioxide generation that needs to be vented along with steam. The cost of this steam addition is the largest differentiator between acid POX operation and alkaline POX from a cost comparison. However, alkaline POX can offset these costs through reduced acid usage for pre-acidulation and decreased alkali reagent consumption for subsequent neutralization. This paper reviews the specific operating cost impacts of acid/base consumption between alkaline and acidic POX with ores which require pre-acidulation, the overall economics of alkaline POX, and the regimes in which alkaline POX is economically favorable. The findings aim to guide industry professionals in making informed decisions for alkaline POX adoption by providing a summary view of its operational benefits and costs, contributing to the development of cost-effective and sustainable gold ore processing techniques.

Feb 1, 2025

By B. M. Davis

The uncertainty associated with a reserve estimate has generally been expressed as a subjective ranking rather than a quantitative expression of either reliability or uncertainty. These rankings of estimate reliability have taken a very nonquantitative bent as well. For example, the U.S. Securities and Exchange Commission definition of proven reserves is given as: Reserves for which (a) quantity is computed from dimensions revealed in outcrops, trenches, workings, or drill holes, grade and/or quality are computed from the results of detailed sampling and (b) the sites for inspection, sampling and measurement are spaced so closely and the geologic character is so well-defined that size, shape, depth and mineral content of reserves are well-established. (U.S. SEC, Form S-18, Item 17A)

Jan 1, 1992

By James W. Derrick

General widespread interest in fine coal cleaning circuits did not occur in the United States until the mid 1960's. Up until this period the relatively low price for which bituminous coal was sold did not justify for many operators the capital and maintenance costs associated with the beneficiation and drying of fine coal. However, with current growing interest in this area, the introduction of new types of process equipment along with modifications to existing components is occuring to maximize the recovery of coal fines. In 1973 Derrick Manufacturing Corporation introduced high frequency screening machinery into the coal industry. The first design consisted of a 4 ft. wide 18 ft. long single deck screen frame with three 100 mesh woven wire screen surfaces divided by repulping troughs for the addition of wash water. In addition, a special slotted rubber dewatering deck was installed on the discharge end of the unit to assure adequate dewatering of the screen oversize. This panel had nominal 25 mesh X 3.0" slotted openings. The machine was also equipped with a special high speed-low amplitude (3600 RPM .032" % AMP.) integral vibrator.

Jan 1, 1983

By Brij M. Moudgil

Flotation was introduced in phosphate rock processing in the late twenties and since then it has been an important part of the concentration process. More than two thirds of the rock produced in Florida is upgraded by the flotation process. Since no crushing or milling steps are involved in the material preparation, the flotation plant feed is coarser than in most other mineral flotation systems. During hydraulic processing of the rock, particles in the size range of -14, +150 mesh constitute the flotation feed. This size fraction is further classified by hydraulic sizers, stationary screens and vibrating screens into a coarse (-14, +35 mesh) and a fine (-35, +150 mesh) flotation feed. The flotation techniques for concentrating the fine feed as practiced by the Florida Phosphate producers have been standardized over the years, however, methods for upgrading the coarse feed differ from plant to plant. In this paper an effort has been made to present relative merits of the techniques employed for concentrating the coarse phosphate rock..

Jan 1, 1977

By C. E. Chapin

The Hansen orebody is a large (1 2 million kg U3O8, 0.08% U3O8 average grade) sandstone-type uranium deposit in the Eocene Echo Park Formation of central Colorado. The deposit occurs in carbonaceous braided-stream sandstones that are part of a wet-alluvial-fan complex that prograded eastward across a narrow strike-slip basin. The Echo Park basin is one of a series of basins that formed along the east side of the Colorado Plateau as it was translated northward during the Eocene culmination of the Laramide orogeny. The valleys of east- and southeast- flowing perennial streams, whose courses were transected by the subsiding Echo Park basin, were filled with permeable volcanic and sedimentary rocks during construction of the Oligocene Thirtynine Mile volcanic field. These paleovalleys funneled large volumes of uranium-bearing ground waters through the braided-stream facies of the wet alluvial fan. Uplift of a basement horst downfan from the Hansen orebody reduced transmissivity and helped maintain a reducing environment in the Hansen area; this later became an important factor in preservation of the Hansen orebody. The horst also deflected uranium- bearing ground waters upward into the Oligocene Tallahassee Creek Conglomerate where they formed the Picnic Tree orebody (1.1 million kg U3O8, 0.09% U3O8 average grade) in an altered ash-fall tuff that is essentially barren above the Hansen orebody. Several potential source rocks for uranium are present and range in age from Proterozoic quartz monzonites of Silver Plume age to lower and upper Oligocene ash-flow and ash-fall tuffs. Uranium may have been contributed to the Hansen orebody several times from different sources. Uranium and thorium analyses of ash-flow tuffs indicate that ample uranium was released during cooling and ground-water leaching to form several Hansen orebodies. The host sandstones are conspicuously altered, and their initial high permeability has been greatly reduced by precipitation of intergranular cements, especially clays and opal C-T. The alteration and cementation mineral assemblages and the chemical composition of stagnant ground waters recovered from pump tests indicate that uranium deposition occurred under alkaline, reducing conditions preceded and/or accompanied by bacterial production of framboidal pyrite.

Jan 1, 2013

By D. Gill, R. Burgess, B. Kyslinger

"There is always a demand in the mining industry to improve the safety and efficiency of roof bolting. Since 2008, Anglo American and Fletcher® have been working together to develop a new roof bolter concept that is safer and more ergonomic while maintaining current production rates. The recognized types of machines currently used in South Africa are always under constant review for improvement; however, there are limitations to the current design. The majority of the machines in South Africa are the “Man in Position” roof bolters. There are currently over 200 of these roof bolters in South Africa, with the bulk of the machines being twin-boom units. When operated correctly, these machines are safe, versatile, reliable and productive. However, with the operators located close to the drilling and bolting operations, they can be exposed to operational hazards. In addition, the major amount of material handling can be quite difficult on an operator. Anglo American, with a desire to improve safety, approached Fletcher to develop a remote style machine with simplified controls that maintained the productivity of the twin-boom machines. After several prototypes, the current model was developed. The chassis was designed for better operator comfort. A dual mast drill module was implemented to reduce the total time to bolt a cut. A remote operator’s station was incorporated to remove the operator from the front of the machine. The design was all about producing a safe and ergonomic machine from front to rear. This paper will explain the evolution and technological advancements from earlier prototypes to the current production machine. INTRODUCTION With mining, especially coal extraction, comes the necessity of supporting the roof. Since the 1950’s, the primary method for roof support has been the use of roof bolts. Roof bolting is considered one of the most hazardous jobs in underground coal mining. In 2004, there were 3,405 injuries reported to MSHA (Mine Safety and Health Administration). Of those injuries, 17 percent were associated with bolting machines (593 injuries). The majority of the injuries resulted from rock falling from supported roof. However, injuries involving a part of the body being struck by, or caught between, during bolting and drilling occurred with relatively high frequency (Burgess and Steiner). Roof drilling and bolt installation is labor intensive and repetitive. These labor intensive and repetitive requirements can lead to cumulative trauma. Operators are expected to perform a considerable amount of lifting, carrying, bending, reaching and stretching. Back and shoulders become sore from bending and twisting to install bolts or lift and position drill steels, wrenches and bolts. Confined operator spaces also contribute to difficult and awkward working positions for the operators (Cornelius and Turin)."

Jan 1, 2017

By David Brown, Adrian St. John, John Comins, Mike King

"INTRODUCTION The Crossrail project provides an East-West link across London enabling an additional 200 million journeys each year linking up major business centres and existing transportation interchanges, while reducing congestion at street level and within the current underground system. The project has built major structures in Sprayed Concrete Linings (SCL), including 5 new stations, 6 crossover caverns and numerous passages, adits and ventilation tunnels. Construction has taken approximately 4 years, and has involved the spraying of over 200,000m3 of concrete. At the start of the project there was a lack of available records from previous projects concerning concrete falls, which hindered risk assessments and the ability to make meaningful comparisons around spraying or material performance. This paper redresses this lack of data by providing information on falls experienced on this project and makes recommendations to assist future projects. Construction Methods Table 1 below summarises the main contracts with elements of permanent SCL. The listed primary lining lengths include pilot tunnels, side drift tunnels and enlargements as separate tunnels.A range of construction sequences were used in order to deal with the design requirements, geometry, and the ground and ground water conditions. The following briefly summarises the build up by layers, with typical design dimensions provided for a platform sized tunnel (approximately 9m internal diameter), excluding tolerance allowances. Some linings were sprayed in more than one layer to allow for inclusion of reinforcement layers or to avoid a too aggressive build-up of thickness: •,Initial shotcrete, or sealing, layer (ISL) of 75mm followed by a Primary Lining (PL) of 300mm. •,Regulating layer of 40mm followed by a Waterproof membrane (Sprayed membrane, 3-6mm). •,Secondary lining (SL) of 250mm with a separate sprayed fire protection layer (FPL) of 50mm."

Jan 1, 2016

By B. W. Cavender

Innovative mining and metallurgical operating techniques and processes can be identified and developed by analyzing changes as they occurs within the mine, plant, technology or industry. Sources of change to be monitored for innovative opportunities include unexpected successes or failures, incongruities between perceived and actual events, process needs, changes in perceptions and the development of new knowledge. Innovation can be organized, practiced and managed. The perception of change as an opportunity rather than a threat is mandatory, as is the systematic measurement of innovative performance. Innovation is enhanced by specifically designed policies regarding organizational structure and staffing, daily management practices and compensation and incentives.

Jan 1, 1996

By Richard E. Hucko

The Coal Preparation Division of the Pittsburgh Mining Technology Center conducted an investigation to assess and compare the pyritic sulfur reduction potential of coal-pyrite flotation and high-gradient magnetic separation (HGMS). Tests were run on three coals--an Upper Freeport bed coal, a Lower Kittanning bed coal, and a Pittsburgh bed coal--to establish grade- recovery relationships characteristic of both processes. Representative portions of each coal sample were crushed to two top sizes--nominal minus 35 mesh (0.5 mm) and nominal minus 100 mesh (0.149 mm)--and subjected to conventional froth flotation. The froth product was then beneficiated by coal-pyrite flotation or HCMS to provide a direct technical comparison of the two processes. At minus 35 mesh (0.5 mm), the size normally employed for coal flotation, both coal-pyrite flotation and HGMS effectively separated pyrite from coal, and the performance of the two processes was essentially the same. At a size of minus 100 mesh (0.149 mm) , however, the performance of HGMS exceeded that of coal- pyrite flotation. The separations effected by HGMS were more efficient at minus 100 mesh (0.149 mm) than at minus 35 mesh (0.5 mm). On the other hand, it was concluded that either the effectiveness of coal-pyrite flotation decreases with diminishing top size, or the process has not been optimized to treat material finer than 35 mesh (0.5 mm).

Jan 1, 1981

By S. M. Robinson

Wollastonite is recognized as one of the most unique, non-metallic minerals in the world. Its history for use in industrial applications is recent compared to other minerals, however, its distinctive physical properties, such as acicular particle shape, and alkaline pH creates incorporation possibilities ranging from bowling balls to automotive fascia, from ceramic tiles to automotive brakes, and from thermal insulation board to industrial and trade sale coatings. Its future use will be impacted by the exploitation of deposits which will ensure maintenance of the acicularity and purity of this naturally occurring mineral. Additionally, closely held surface treatment technology will open up additional niches requiring highly engineered performance.

Jan 1, 1995

By Frank Matter

The production of ultrafine slurries and powders is possible with small media made out of Si02, A1203, Fe203, Zr03 or other raw materials due to the fact that since approximately 12 years from now, entirely new machines have been developed which allow to use this small media for the production of ultrafine pigments. Basically we distinguish between two grinding methods which are: A.) Dry Grinding with Air Classification: This method is used for more than fifty years but only since four years this technology is realized with small grinding media. Many problems like cooling, abrasion, control of the media flow, separation media from product, grinding media recycling etc. had to be resolved before it was possible to get in full production with this new system. Hereafter a flow-sheet of such a TRZK mill with an air classifier especially designed to produce end products with a top size between 2,5 and 3,0 micron and with an average particle size between 0,3 and 0,5 micron.

Jan 1, 1983

By Werner Wenzel

Methods to increase the gas penetration through sinter layers. In the field of agglomeration, sintering has gained importance, specially in Europe; in Best-Europe this trend will continue till the year 1980, since it is quite probable that in the blast furnace burdens with 50-60 sinter, 10-20 % pellets and 20-25 % ore lumps will be employed. In order to meet this demand for sinter, new sinter bands with reaction areas between 300-400 m2 will be constructed. Chemical and physical phenomena during the Suction-Draught-sinter process. Iron ore sintering is generally considered as a burning process where the material contains 90-95 % ash i.e. non-combustible ingredients. Sintering represents a heterogeneous exothermic reaction in which the chemical phenomena as combustion, calcination, hydration, reduction and oxydation are superposed by physical phenomena. The physical phenomena are devided into material transport and simultaniously occurring heat transport processes. The velocity of these combined physico-chemical reactions i.e. the change in the reaction site per unit time determine the efficiency of the sinter process. The gas permeability as an important criterion of heat transport during the Suction-Draught sinter process.

Jan 1, 1971

By Nancy J. Wheatley

I. INTRODUCTION The Massachusetts Water Resources Authority (MWRA) is a regional water and sewerage authority which provides wholesale water and sewer services to the Metropolitan Boston area. The MWRA was created by the Massachusetts Legislature as an independent authority in 1985 following the filing of a lawsuit in federal court to correct the pollution of Boston Harbor resulting from inadequate and inadequately maintained sewerage facilities. Immediately upon its creation, the MWRA began to tackle treatment plant issues, including addressing the need for a secondary treatment plant, planning for ceasing ocean discharging of sludge, and making interim repairs to the existing, antiquated treatment plants. The MWRA's initial activities led to a court-ordered schedule for construction of a single new primary and secondary treatment facility, for development of sludge management plan focussed principally on reuse, and for completion of a short term program of repairs to existing facilities. Once a schedule for completing these activities had been negotiated, the U.S. Environmental Protection Agency (EPA), a plaintiff in the federal court case, asked that the MWRA take "responsibility" for controlling discharges from combined sewer overflows (CSOs) within its service area. Combined sewers (sewers in which both sanitary sewage and storm water runoff are carried in a single pipe) presently discharge over 10 billion gallons of untreated wastewater into Boston Harbor and its [ ]

Jan 1, 1991

By Robert C. Pease

Siskon Gold has started gold production at the San Juan deposit in northern California. The mine is located about 27 km (17 miles) north of Nevada City, CA (Fig. 1). It is scheduled to be-come the largest underground gold mine in California. It is situated in the western foothills of the Sierra Nevada Mountains in the Mother Lode gold belt. The property consists of 8 km2 (2,000 acres) of patented land. It is situated in a topographically high area known as San Juan Ridge, which is 213 m (700 ft) above and between the Middle Yuba and South Yuba rivers. The elevation is between 790 and 914 m (2,600 and 3,000ft) above sea level. Annual precipitation averages 1,346mm (53 in.). Most of that falls between November and April.

Jan 1, 1996

By Robert M. Stevens, Arnoldo Acuña

INTRODUCTION In the early 1950s, underground miners and tunnel¬ing contractors were experimenting with ways to supple¬ment or eliminate track-bound loading and hauling equipment. Diesel-powered crawler and rubber-tire mounted front-end loaders and trucks designed for use on the surface were being modified and tried with limited but encouraging success. Miners began working with interested manufacturers to explore the develop¬ment of vehicles specifically designed to meet the de¬mands and constraints of underground material han¬dling. By the mid 1960s, load-haul-dump (LHD) vehicles were firmly established as a fundamental part of what has become known as the "trackless" mining concept, used in many mines and many countries around the world. The flexibility, mobility, and versatility of these units have given the industry a useful tool and have added new dimensions to mine development and produc¬tion. Many old mines have been redesigned to accom¬modate these trackless vehicles, and few new mining plans have failed to find some use for the concept during some phase of development and production. By 1977, several manufacturers in several different countries were producing a variety of LHD vehicles to meet the growing worldwide demand. GENERAL DESCRIPTION LHD vehicles combine certain characteristics of conventional front-end loaders and dump trucks, spe¬cifically designed for materials handling in underground mining and tunneling. The design intent is to provide one vehicle with one man, with the vehicle loading itself, hauling the load over level or inclined haulageways, and dumping the load. A typical production cycle of the most popular units has the operator driving the vehicle forward, forcing the bucket into the muck at or near floor level, and using the tractive effort of the vehicle and the prying action of the bucket to roll out and tilt back the load as shown in Fig. 1. With the bucket rolled back into the carrying position on the boom and the boom resting on the main frame of the vehicle, the load is hauled (trammed) to the dump point as shown in Fig. 2. At the dump point, the boom is raised, the bucket is rolled forward, and the load slides out as shown in Fig. 3. After dumping, the bucket is rolled back to the carrying position, the boom is returned to rest on the main frame, and the unit is driven back to the loading point for another load. There are two other types of LHD units that are slightly different in the cycles that they perform. One uses a hopper arrangement carried on the front of the machine, with a small bucket mounted ahead of the hopper. Several passes with the small bucket load the hopper, which is dumped by opening its floor. Al¬though this concept is several years old, it has gained less than 0.5% of the total market. The most recent LHD concept differs in that it has one bucket nesting inside another. The smaller inner bucket is loaded first, and it is then tilted back and above the larger bucket. When the larger bucket has been loaded, it is rolled back, and the total load is trammed to the dumping point. The dumping operation tilts the buckets in the reverse order from that of the loading operation. The impact of this new concept on the mining industry has not been measured yet. This chapter concentrates on the LHD vehicles employing the cycle described by Figs. 1 through 3, since these LHD units constitute an estimated 99% of the units in current use. MAIN VEHICLE FEATURES In general, the LHD vehicles available from most manufacturers share the same basic features.

Jan 1, 1982

By Ch. R. V. S. Nagesh, Ramesh Naidu Mandapati, Venkata Swamy Nalajala, Tondepu Subbaiah, Naga Jyothi Kothamasu

Leaching studies of magnesite obtained from Tamilnadu Magnesite Limited, Salem, have been carried out using hydrochloric acid leaching and percentage of magnesium chloride recovered was estimated. The variables considered in this study were the following: duration of leaching, volume percentage of hydrochloric acid, temperature, and pulp density. Percentage recovery of magnesium chloride increased with duration of the leaching, volume % of concentrated hydrochloric acid, and temperature. Percentage recovery of magnesium chloride decreased with increase of pulp density. The optimum conditions found to be pulp density (10%), hydrochloric acid concentration (30%), duration of leaching (2 h), and temperature (348.15 K). Iron was removed by treating the leach liquor with hydrogen peroxide and by raising the pH to 3.5–4. The purified leach liquor was subjected to spray drying for producing high pure magnesium chloride.

Jun 7, 2022

By Irving Hoch

INTRODUCTION The demand for tunnelling can be related to urban population size and density; often, tunnelling occurs when a certain city size and density threshold is reached, and increases thereafter as a function of those population characteristics. Subways for rail mass transit are the most notable example, of course, but tunnels for water supply and perhaps for sewerage can also be related to size and density. As cities grow large they sometimes outgrow their local water supply and have to import water from distant places via tunnels; witness New York City, Los Angeles and San Francisco. And it has been suggested that Chicago use deep tunnels for storm water storage because tertiary treatment to meet water quality standards will require treating storm water runoff.(1) Other uses of underground space also increase with urban density, e.g., underground parking, concourses and shopping centers such as Rockefeller Center in New York City and the Place Ville-Marie in Montreal. These examples can be viewed as illustrative of the central point of urban land economics. As the number of people locating in a place increase, they bid up land values and make the more intensive use of land economic, with land defined to embrace the space both above and below the surface. Hence, we are led to think about the city, and of urban land use, in three dimensions. Now, if we accept the relation of underground space use to urban size and density, recent demographic trends seem anything but hopeful for future tunnelling demand: urban density is declining, population growth is slowing down generally, and there

Jan 1, 1974