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By T. Veneroso

Comminution is the process by which rock or ore is reduced to a size where the liberation of the minerals is maximized without changing the chemical or physical properties of the rock. Comminution accounts for about 50% of all energy that mines use (Klein et al., 2018). Growing demands from stakeholders and shareholders for sustainable development and CO2 reduction will increase the need for energy-efficient comminution. Ores with different mineralogical characteristics, textures, strengths, apparent stiffness, and mass-specific fracture energies need to be processed with a specific, new, and efficient comminution technology to increase the production and profitability of mining companies. The adoption of crusher wear parts built with new materials, such as non-Hadfield manganese steel or synthetic materials or traditional manganese with wear-resistant components, could improve the efficiency of the crushers, reduce downtime, increase production, improve the desired P80 (the aperture through which 80% of the product will pass) product size distribution, and enhance mine safety.

Feb 1, 2023

By Vas P. Srinivasa

A comminution circuit is an important integral part of a mineral processing plant. Nearly 40% of the capital cost and 30 to 40% of the operating cost are taken up by the crushing and grinding circuit. Therefore, considerable care should be given to the design and selection of this circuit. Several factors affect the selection of a comminution circuit--energy consumption, avail- ability of the equipment, the remoteness of location, and availability of trained personnel, to mention a few. Each of these factors influences the choice. Selecting a comminution circuit strictly on lower capital cost may not be optimal. Crushing and grinding circuits are usually site specific and should be selected - only after careful analysis of all the factors involved. The objective of this paper is to show the effect of these factors, which are extranious to capital cost. Usually, the capital cost of a semiautogenous grinding circuit is lower than that of an equivalent conventional circuit. However, due to lower equipment availability and high power costs in certain locations, the economic advantage of lower capital cost is lost. Analysis indicates that a break even point occurs at a power cost of 5¢/kWh. This paper describes the procedure utilized for selecting the most economic comminution circuit and states the conditions applicable for each cominution circuit.

Jan 1, 1983

By J. T. Carlson

Dolomite is an objectionable impurity in phosphate ores, due to its MgO content. Even though dolomite and apatite liberate at a coarse size, the very similar densities of dolomite and apatite makes density separations difficult. However, if operated correctly, jigging can be a very efficient process. This has led to the development of a unique laboratory scale jig that allows for easy alteration of effective jigging properties. Key jigging parameters have been investigated for the separation of dolomite from phosphate ores. It was found that a pulsation rate of approximately 200 pulses/minute worked best for separating dolomite from apatite.

Jan 1, 2010

By P. W. Finck

Detailed mapping, using a large diameter diamond-drill in conjunction with high resolution reflection seismics, has increased known resources of kaolin clay and glass-grade silica sand from scattered deposits generally < 1 km2 to large areas of Cretaceous valley fill up to 130 m thick. Detailed chemical and physical analysis of drill core is presently underway. Silica sand deposits intersected in this study are up to 99.4 % SiO2 without beneficiation. Light grey to white kaolin clays identified by XRD and DT A have concentrations values (without beneficiation) up to 47.28% SiO2, 37.44% Al2O3, 0.45% Fe2O3, 0.49% K2O, 0.07% Nap, 0.07% CaO and 0.39% MgO.

Jan 1, 1996

By J. P. Allen

Cobalt, nickel, and manganese can be recovered quickly, cleanly, and selectively from cobalt-rich manganese crust by leaching in dilute acid solutions in the presence of hydrogen peroxide. Common selective precipitation methods can then be used to recover these metals from the leach liquor. The leaching reaction produces only oxygen as a byproduct, and the waste residue from leaching was tested and found to be non-hazardous under existing EPA specifications. The leaching process is effective in either fresh water or seawater. This research is a part of the Bureau of Mines program to identify the mineral resources of the Exclusive Economic Zone and devise methods for recovering their valuable components.

Jan 1, 1990

By T. H. Phillips

The Mission Mine is an open-pit copper mine located 18 miles south of Tucson, Arizona in the eastern foothills of the Sierrita Mountains. Mining is done on 40 foot benches using P & H 2100 shovels and 170-ton Terex trucks. Drilling is accomplished With two (2) Bucyrus-Erie 45R?s, one (1) Bucyrus-Erie 60R and two (2) Ingersoll Rand T-5?s. For secondary drilling. a Joy VCR-ISO truck mounted drill is used. The mine is currently operating 3 shifts/day, 7 days/week at 59,100 tons per day, with the mill receiving 28,500 tons per day. The management of the drilling and blasting program requires extensive record keeping in all phases of the operation. This is essential in order to evaluate different products and procedures.

Jan 1, 1988

In this paper, a number of novel hypotheses that provide a fresh perspective on the characterization of strata movements associated with longwall mining are developed by analyzing subsidence measurements with an influence- function-based computer program. With this influence-function technique, easily obtained surface displacements can be used to determine some of the complicated, expensive, and difficult to measure movements of the immediate roof strata in a longwall panel. The primary hypothesis developed by this analysis proposes the existence of an area of partial roof caving near the edge of a panel called the "edge effect." A second hypothesis, interrelated with the first, promotes the importance of the effect of gate-entry closure on the observed strata movements. Both the primary edge effect hypothesis and the secondary hypothesis concerning gate-entry closure are justified and quantified in an extensive analysis of surface subsidence that uses supporting information from related theories, design criteria and insitu measurements. Next, the edge effect and the gate closure hypotheses are extended further and used to provide an explanation of the complex subsidence interaction of adjacent longwall panels in what is termed a "redisturbed" effect. Finally, in the conclusions of this paper, the importance of accurately understanding these longwall strata movements for proper subsidence prediction or gate design is stressed.

Jan 1, 1986

P.T. Freeport Indonesia&apos;s latest expansion has increased total mill throughput to 125,000 dry metric tonnes per day. The most recent expansion included the installation of a Semi Autogenous Mill designed to treat more ore than any other single SAG mill currently operating in the world. Also included in the expansion were two large ball mills, rougher and cleaner flotation including conventional and column cells and a regrind circuit. All equipment is supported by a modem distributed control system. This paper describes the design considerations, construction, commissioning and start-up of the SAG concentrator and support facilities and includes an overview of the oreflow and milling facilities.

Jan 1, 1996

By Giuseppe Gaspari, Xiangrong Wang

The pandemic emergency is forcing transit agencies to define strategies allowing social distancing, which are more challenging in underground interchange stations in crowded downtown cores. Toronto Transit Commission’s (TTC’s) Bloor-Yonge Station Capacity Improvement Project in Toronto was approved to meet increasing demand and represents an opportunity to fight COVID-19. This paper discusses cost-effective solutions in expanding the cut-and-cover station box over the existing Toronto Subway Line 2 and connecting it through ventilation openings in the cast-iron tunnel liner. Potential uplift risks and structural damage due to minimal vertical clearance were analyzed via three-dimensional finite element analyses with advanced constitutive laws to simulate the multi-stage construction process. Based on the simulation results, a series of countermeasures, including excavation support systems, king posts, ground-consolidations, and liner reinforcements were integrated into comprehensive design options to ensure the serviceability and structural integrity of the subway tunnels.

Jun 13, 2021

By V. Gangrade, J. Addis, S. Vanderslice

Researchers at the National Institute for Occupational Safety and Health (NIOSH) are conducting research to improve the ventilation of large-opening underground stone mines. The mine ventilation in these mines are characterized by: (1) challenges related to keeping airflow velocities high enough to effectively remove or dilute airborne contaminants, (2) low pressure losses needed to move large air volumes of air, and (3) costly stoppings needed to direct ventilation airflows. Each of two field studies was dedicated to specific focus areas. The first focus area was the characterization of underground mine ventilation airflow. The primary means of airflow control in stone mines is through the use of freestanding booster fans. The primary goal of this study was to identify the effectiveness of various fan types and optimize their placement. Both traverse and grid-based airflow readings were taken at various distances from the fans, ranging from 70 ft to 425 ft away from the fan. The air readings were taken using a vane-anemometer and a handheld hotwire anemometer. The data was used to develop precise computational fluid dynamics models. The second focus area was to determine diesel particulate matter (DPM) concentrations in the mine. For large-opening underground stone mines, controlling DPM exposures dictates the design of the ventilation system. Therefore, researchers carried out the DPM sampling campaign to identify potential areas of concern within the mine. The samples collected during the campaign were analyzed using NIOSH Method 5040. The sampling was done using the Mine Safety and Health Administration’s (MSHA) compliance sampling methodology.

Feb 1, 2023

By R. A. Wyman

"The froth flotation process was patented by E.L. Sulman, H.F.K. Pickard, and John Ballot in 1906 . . . . . . . . . .James M. Hyde installed the first froth flotation process in the U.S., about August 1, 1911, at the Basin Reduction Co. plant, Basin, Montana . . . . . . . . . .By 1914, 42 mining companies were operating or experimenting with the flotation process . . . . . . . . . .The period 1930 to 1960 saw the application of flotation spread to nonsulphide ores and become the key factor in the economic production of many industrial minerals". So states FROTH FLOTATION, 50th Anniversary Volume, published by AIME in 1962. It is interesting, to observe that the Mines Branch, now part of the Canadian Department of Energy, Mines and Resources, was established in 1907 through an act of Parliament entitled, "The Nines and Geology Act". In 1911, a mineral dressing group was formed and a laboratory was constructed. By 1921, an engineer was devoting full time to industrial mineral processing problems.

Jan 1, 1971

By Louis M. Schlesinger

KMG Minerals, Inc., a mica-feldspar-quartz producer in Kings Mountain, N.C., uses about 50% of its plant&apos;s -200 mesh slimes to manufacture brick. However, the company is unable to market the remaining 50% of this fine mineral mixture. The NCSU Minerals Research Laboratory operated a pilot plant to process these slimes to produce an additional product. The process, consisting of blunging and hydraulic sizing, was designed to separate a kaolin-enriched -270 mesh product from the bulk of the coarser +270 mesh "grit" minerals. Size analysis showed that this product was 80% finer than 20 microns and 50% finer than 6 microns (in equivalent spherical diameter). An evaluation indicated that it is a hydrous aluminum silicate that might be suitable in the filler and extender markets for traffic paint, some types of plastics, joint cements, and dusting compounds. Because of its high viscosity, it will be difficult to use more than a small percentage in cast ceramic bodies. However, it might be possible to use up to 10% in extruded ceramic bodies (i.e., electrical porcelain). The 15.2 cm (6 in,) diameter Linatex Hydrosizer was tested using a range of teeter water flowrates, so that the net rise velocity was varied from 0.10 cm/s to 0.40 cm/s. The solid feed rate to the sizer was maintained at approximately 1.1 t/hr/m2 (0.12 ton/hr/ft2). Tests were run using both "shallow" (i.e., 6 in.) and "deep" (i.e., 15 in. teetered beds. The best overall result was obtained when the sizer was operated with the "deep" teeter bed and a net rise velocity of 0.10 cm/s. About 97% of the +270 mesh material was rejected and approximately 79% of the -270 mesh material was recovered in a 14% solids slurry.

Jan 1, 1994

By Felicia F. Peng

The plant data were collected from three streams around a dense medium drum for coarse coal cleaning operated at various volumetric ratio of medium-to-feed. The effect of the volumetric ratio of medium-to-feed (MF) and particle sizes on the performance criteria, g50 and Ep, of the dense medium drum. These measured data were adjusted and calculated for the yields and balanced relative density distributions by mass balanced method based on the statistic principle. These balanced data were then used to formulate the mathematical models of the separation distribution curves for the various feed size intervals. The correlation equations for the g50 and Ep as the function of inverse of the feed size, and MF and total throughput were established. A numerical algorithm utilizing the Secant method, based on the root searching principle, was developed for yield optimization and simulation of dense medium drum separation to improve the separation efficiency and hence the product yield. The relationships between the direct ash content and relative density of the particles in feed and the products were established and incorporated into the numerical algorithm for predicting the product quality.

Jan 1, 1996

By M. L. Free, N. Dhawan, M. S. Safarzadeh, J. D. Miller, M. S. Moats

"The drum agglomeration of nickel laterite and gold ores has been optimized through the design of experiments (DOE) using a Taguchi L16 (45) orthogonal array to determine the optimum conditions for maximizing average agglomerate size and minimizing the amount of fines. The effects of controllable operating factors including moisture content (nickel laterite ore: 34-37%; gold ore: 7-10%), retention time (2-3.5 min), drum speed (15-45% critical speed), drum load (nickel laterite ore: 8-32 %; gold ore: 6-22%) and acid concentration (150-600 g/L) on the performance of the agglomeration process were studied.For nickel laterite ore, maximum average agglomerate size and minimum percent fines (-1 mm) occurred under the following conditions: drum load (23.7%), moisture (36.5%), time (3 min), drum speed (30% critical speed) and acid concentration (150 g/L). Under the studied nickel laterite ore conditions, the most effective parameters for maximizing average agglomerate size and minimizing the amount of fines were found to be drum load and acid concentration, respectively. Drum speed had a statistically significant effect on minimizing the amount of fines. Maximum average agglomerate size and minimum percent fines (-1 mm) for gold ore occurred under the following conditions: drum load (19.3%), moisture (8.5%), time (2 min 15 s) and drum speed (40% critical). The most significant factors for maximizing average agglomerate size and minimizing the amount of fines for gold ore were found to be drum load, time and moisture.IntroductionSeveral heap leach operations have experienced problems in terms of poor recovery due to percolation issues caused by low-grade complex ores, tailings and clayey deposits. Poor percolation can lead to low metal extraction due to solution channeling or the development of impermeable/dead zones within the heap (Dhawan et al., 2012; Kappes, 2005). Improper heap building practices such as the use of loose agglomerates and inadequate attention toward the presence of clay minerals have been among the main reasons for percolation issues. During the transport of ore material, severe segregation of the material can occur. To overcome percolation problems, a major improvement was made through the introduction of agglomeration prior to ore placement. If the ore particles and agglomerates are of similar size, segregation can be avoided to a great extent (Dhawan et al., 2013; Kinard and Schweizer, 1987; McClelland and van Zyl, 1988). Agglomeration improves the uniform percolation of solution through ore heaps and is applicable to many ores, wastes and milled tailings (Bouffard, 2005; Dhawan et al., 2013). Manning and Kappes (2005) reported agglomeration/ stacking accounts for ~14% of the total heap leaching operating cost. The cost of binder is a primary contributor toward the total cost. Also, the lack of consistent quality control tests for agglomerate often leads to operational problems. The details are mentioned elsewhere (Dhawan et al., 2013). Considering the significant contribution of the agglomeration/stacking step toward the total heap leach operating cost, it is appropriate to study the agglomeration behavior and its optimization for two different ores. The reason to study the same parameters for different ores is the fact that significant variability in the agglomeration behavior of different ores has been reported to exist in industrial operations."

Jan 1, 2015

By Subhas G. Malghan

Feldspathic deposits occur widely throughout the United States, but North Carolina, California, Connecticut and South Carolina accounted for over 80% of the total domestic feldspar output for the year 1973.1 Pegmatites and granites constitute the major feldspar reserves of the United States,2 and in addition, feldspar is produced as a by-product by firms whose major products are spodumene and mica.3 Feldspar is concentrated by hand-cobbing and flotation; the latter forms the major method of separating and concentrating feldspar. Feldspar flotation is practiced in the United States, Mexico, Finland, Norway, West Germany, Japan and the USSR. According to the U. S. Bureau of Mines estimates, the production of feldspar in the United States and rest of the world were 704,000 tons and 2,514,000 tons respectively. Feldspar is principally used as a flux in making glass, pottery, porcelain, enamel,-tile and other ceramic products. In recent years, the domestic feldspar industry is faced with a number of problems. As a result of increased cost of energy and the introduction in 1972 of new legislative programs relating to air, water, and noise pollution, land-use restrictions, and mined-land rehabilitation, the production costs have increased. Apart from the increased cost of operation, an operational problem exists with the feldspar producers in North Carolina, especially those in the Spruce Pine area. This problem is concerned with the use of hydrofluoric acid in the feldspar flotation. Feldspar producers in Spruce Pine, North Carolina have been discharging process waste water into the North Toe River. The mill waste water contains active fluoride ions. Fluoride in excessive concentrations is undesirable in waters used for drinking. It is stated that water

Jan 1, 1976

By T. J. Smolik

The Golden Sunlight Mine started full-scale operations in February 1983, with a conventional open-pit mine supplying 4464 tonnes (5000 tons) per day of milling ore. After crushing and grinding, the ore is leached with cyanide solution in large agitation tanks. Soluble gold values are removed from the sand portion of the leached ore with five stages of countercurrent washing cyclones. After thickening of the cyclone-wash overflow slurry, the gold is recovered in activated carbon with a six-stage carbon-in-pulp circuit and a five-stage upflow carbon column circuit. Pressure stripping, carbon reactivation, electro-winning and refining complete the gold recovery process.

Jan 1, 1984

By Nathaniel Arbiter

A fully-instrumented driving mechanism has been constructed to study the power, aerating and solid suspension characteristics of several laboratory flotation machines. Machines operating over normal flotation speed ranges give constant power numbers in liquid&apos; systems indicating that they operate under fully baffled turbulent flow conditions. Owing to lack of geometrical scaling, power numbers for different sizes of cells of the same make are different. Even larger differences occur between cells of different manufactures. For a given impeller, varying the tank size did not significantly affect the power consumption. Tank geometry and baffling has a slight effect on power consumption with shrouded impellers. For a given impeller speed, suspension height decreases while power increases with increasing mass of solids in suspension. While power consumption is hardly affected by particle size and clearance between the impeller and tank bottom, the suspension height significantly increases as clearance increases and as particle size decreases. Aeration was found to affect not only power but also the suspension characteristics of the machine. For closely sized particles drastic sedimentation occurred when a critical value of the air flow number was exceeded. The critical air flow number decreased with increasing particle size. This effect was less marked with a wide particle size range. The self-aerating capacity of flotation machines increases with cell size at a given speed for the same impeller-shroud system, but decreases in the presence of frother and solids. Equations have been established for correlating all of the studied variables. Data taken from the literature were also correlated with these equations.

Jan 1, 1968

By Shiou-Chuan Sun

Notwithstanding the fact that unsaturated fatty acids are used in preference to saturated acids for most flotation purposes, information regarding their collecting properties is sketchy. Keck, Eggleston, and Lowry1 reported in 1939 that the collecting power of fatty acids on hematite decreased in the order of oleic, lauric, myristic, palmitic, and caprylic acid. Keck and Jasberg2 described in the same year that "unsaturated oleic acid with 18 carbon atoms was a better collector than saturated stearic acid" for floating magnetite. Gaudin and Cole3 stated in 1953 that the double bonds of oleic and linoleic acid were not oxidized during the flotation of fluorite, whereas the double bonds of linolenic acid were measurably altered even after one single flotation step. In August, 1953, Hukki and Vartiainen4 concluded that the collecting power of palmitic, oleic, linoleic, and linolenic acids on ilmenite, magnetite, pyrite, and rutile increased with an increasing number of double bonds in the acid molecules. This was subsequently proved to be generally true for the flotation of mapganese5, phosphate6, and magnetite7. The above cited literature indicates that, prior to the present paper, only about ten minerals were tested with pure unsaturated fatty acids as collectors.

Jan 1, 1959

By Andrew Trusiak

Brunswick Mining, employing approximately 1600 employees, is located 40 km south of the city of Bathurst in north eastern New Brunswick. The mine has operated as two lead-zinc operations - the underground mine(No.12) and the open pit mine (No.6). The open pit orebody is presently being&apos; mined by underground methods. It is expected that the No.12 mine will furnish the entire ore supply by the end of 1981. The flotation practice prior to 1971 has been described by Neumann and Schnarr(1) and by Erskine (2). More recently, the current flotation practice has been described by McTavish(3) and deals with some major circuit modifications between 1972 and 1978. The period 1978 to 1980 has seen the completion of. a major flotation cell replacement and expansion program for the No.6 concentrator, and the implementation of computer control in the No. 12 CuPb and Zn flotation circuits.

Jan 1, 1981

By Trenton Cohen, Joseph McDivitt, Shimi Tzobery, Joseph Sinacori, Scott Zylstra

The 2-mile Beach Interceptor Sewer Tunnel was constructed in 1954 to then-current mining and construction standards. Due to its lifespan and deteriorating condition it is now being stabilized and rehabilitated using conventional excavation and ground support. At its southern end, below the prestigious Three Arch Bay community, the original tunnel alignment passes under a historic landslide where the tunnel was sand-backfilled and capped by bulkheads in 1957 due to severe and caving ground conditions. Video footage of the existing 21- inch clay pipe showed that the pipe is severely damaged, which could potentially cause a catastrophic pipeline failure and sewage spill into the Pacific Ocean. This paper summarizes the thorough investigation and design process, tunnel realignment construction and monitoring, and the notable cooperation between all parties to overcome the project risks.

Dec 1, 2022