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By David I. Smith, Kenneth Arnold, Bryan Aweh, Vincent Falkowsk, Brian Lakin, Andy Fer

Nassau County, New York, is undertaking several projects to improve the water quality in the Western Bays of Long Island. A major step forward will be the completion of the Bay Park Conveyance Project, which will divert most treated effluent away from the Western Bays to an existing ocean outfall at the Cedar Creek Water Pollution Control Plant. The ongoing works include 3.6 miles of microtunneling, 7 miles of sliplining, 14 shafts, and a 75 MGD pump station. This paper provides an overview of the design and an update on construction progress through December 2022. The project is a collaborative effort between Nassau County, New York State Department of Environmental Conservation, the design-builder, and various consultants.

Jun 13, 2023

By W. J. Miles

Diatomaceous earth or diatomite is a sedimentary rock of organic origin that is composed principally of the silicious skeletal remains of diatoms. Diatoms are microscopic single cell acquatic plants that are related to algae. Diatoms first became abundant in the Cretaceous period from about 65 to 135 million years ago. Most of the commercial deposits are of Pliocene through recent age, and are younger than 35 million years. Diatoms are still abundant in present day lakes and seas. The living diatom is supported and protected by two half cell walls or valves united by a connecting band or girdle. These valves are composed of opaline silica extracted from the water in which the diatom lives. After death of the diatom, the silicious remains settle in the lake or sea and accumulate at variable rates approaching several millimeters per year for very active diatom colonies. This accumulation of silicious sediments, after decay of the organism, burial, and uplift, can result in the formation of diatomaceous earth deposits.

Jan 1, 1987

By Elżbieta Węglińska, Andrzej Leśniak

The earthquake locations are generally scattered mainly due to a simplified velocity model or seismic event picking errors. The aim of our research was to increase the resolution of the cloud of microseismic events recorded during mining activity in the Bobrek hard coal mine on the 3/503 coalface to delineate seismically active structures using unsupervised machine learning algorithms. We presented results of applying two completely different algorithms for reducing scatter in microseismic location to all events recorded during mining activity on the coalface - the collapsing (proposed by Jones and Stewart in 1997) and condensation (proposed by Kamer in 2015). The collapsing method simplifies the seismic cloud by shifting events inside their error ellipsoids towards local source densities. The error ellipsoids are determined by errors in the measured parameters and seismic network configuration. The advantage of the collapsing method is the partial elimination of blurring of the microseismic cloud. The condensation method reduces the size of the set of seismic events without changing the geometrical information. The reduction of the number of seismic events in the catalog takes place through the condensation of localized events with larger uncertainty into events with lower uncertainty. The spatio-temporal analysis of microseismic events was performed separately on two processed clouds – collapsed and condensed one. We examined how collapsing and condensation methods affect the automatic detection of clusters of microseismicity using density-based spatial clustering of application with noise algorithms. We compared structures detected by the machine learning algorithms in both seismic clouds first created by collapsing and second by the condensation. We identified structures created by mining activity and structures related to the local tectonics activated by mining. The presented results are essential for the prediction of future tremors induced by the mining operation and tectonics and thus ensuring safety in the mine.

Apr 26, 2022

By Carla Da Corte, Kagisego Letsoalo, Ashma Singh

Banded Iron Formations (BIF) are sedimentary rock formations ranging in age from 0.8 to 3.8 billion years and consist of alternating layers of silica and iron. The thickness of the alternating layers varies between and within deposits, with this lithology forming approximately two-thirds of South Africa’s future low-grade hematite resources. The production costs for South African iron ore producers are approximately double that of the largest iron ore producers, namely, Brazil and Australia. This in conjunction with volatile commodity prices, necessitated a cost-sensitive beneficiation strategy for low-grade hematite to sustain the industry and extend life of mine. A BIF sample grading at 44% Fe and comprising predominantly of hematite and quartz with minor amounts of magnetite and goethite was subjected to three fines gravity processing routes to establish the amenability of this sample to beneficiation. To provide flexibility for iron ore producers who still have high-grade resources available, two product grades were considered, namely a 60% Fe product for further blending or a 63% Fe product for direct sales.

May 12, 2023

By J. Hart, P. W. Conrad, S. Rosenthal, R. A. Hogan

The Mining Engineering Department at Montana Technological University (Montana Tech) has a new Mine Safety and Health Administration (MSHA) approved program for Part 46 and Part 48 mine health and safety training. The training program will utilize the facilities and faculty from Montana Tech’s Mining Engineering and Safety, Health, and Industrial Hygiene departments to provide superior mine health and safety training to the mining industry. The faculty of each department includes professionals with experience in safety training and the mining industry. The training program incorporates adult learning techniques and extensive hands-on activities in all training modules. The instruction will exceed MSHA requirements. The resources available on Montana Tech’s campus will be utilized to strengthen the training program providing the mining industry with a world class mine health and safety training program.

Feb 1, 2023

By F. Harold Weber

On July 13, 1967 the San Bernardino County Planning Commission approved publicly a request by American Smelting and Refining Company for a zone variance to conduct a silver mining and milling operation in the Calico district, southern California, Coincidentally, on July 14 the U.S. Treasury halted its sales of silver, and the U.S. free market price quoted rose immediately from $1.30 to $1.77 per ounce. In its request to the commission Asarco stated that about 13,500 to 15,000 tons of rock would be moved daily by surface mining, including 7,000 tons of ore. The ore would be crushed to minus three-quarters inches and the silver recovered "by a chemical process." The grade of the ore was not given, but the company said that it might also recover barite as a byproduct, The operation would employ 150-160 people. Additional activity in the district includes exploration programs by Superior Oil Company and Calico Silver Mines, Ltd. History and production: In retrospect, as the price of silver began to rise in 1961 from 91 cents an ounce, and as Asarco began its exploration program in late 1964, a new era for an old bonanza silver district would seem to have begun. The Calico district has been mined for silver only on a very, very small scale since 1882 to 1896, when an estimated $12 to $20 million (perhaps 15 to 20 million troy ounces) of that metal was produced from the 50-odd mines of the district and vicinity. These mines include the Silver King, Oriental, Waterloo, Garfield, Odessa and Waterman (which is about 8 miles west of the district). Much smaller-valued amounts of barite, gold, lead, and copper also have been produced from the ore deposits of the district; and from 1884 to 1907 the region yielded about $9 million worth of borate minerals.

Jan 1, 1967

By B. R. Stewart

The exclusion of coal fly ash from regulation as a hazardous waste has led to increased interest in returning ash to the coalfields for co-disposal. A multi-year column study used coal refuse with high potential acidity (4% total-S), and two alkaline ashes in various bulk-blends. The unamended refuse acidified rapidly, producing acidic (pH 1.7) leachates, high in dissolved metals. Treatments blended with sufficiently high amounts (20 to 33%) of alkaline ash produced alkaline (PH >8.4) leachates with low metal levels, while lower ash blending rates acidified over time to produce metalliferous leachates. Examination of solid materials indicated that pyrite oxidation was occurring to some extent in all treatments. A regression equation (r = 0.95) was developed to estimate time to net acid release for mixtures of these materials. Ash alkalinity and refuse potential acidity must be balanced to insure water quality for co-disposal environments, or the ash materials should be isolated away from acidic drainage waters.

Jan 1, 1997

By Michael W. Roper

McDermitt Mine is located in northern Humboldt County, Nevada, approximately 5 miles south of the Orgeon-Nevada line (Figure I), within the Opalite Mining District. The operation is a joint venture between Placer Amex Inc., San Francisco, and Mineral Exploration Company Ltd., a limited partnership. The McDermitt orebody possesses a discontinuous, gently dipping blanket-like form within 150 feet of the surface over an area 2200 by 2500 feet. The ore zone averages 20 feet in thickness. The ore minerals consist of cinnabar (HgS) and corderoite (Hg3S2C12) deposited parallel to bedding within argillized, Miocene age, tuffaceous lacustrine sediments. Exploration indicates reserves of approximately 3,000,000 tons ore at a grade of 10 pounds mercury per ton (0.5%) An open pit mining operation utilizing scrapers and bulldozers supplies a concentrator with 700 tons of ore per day. The milling operation consists of autogenous grinding, flotation concentration, concentrate dewatering, and tailing disposal, with a design capacity of 100 tons per hour. The furnace section consists of a concentrate filter, vertical six hearth furnace, mercury condensing system, and exhaust gas scrubbing systems. It has a design capacity of 1000 pounds of dry concentrate per hour. The McDermitt orebody is situated about 2000 feet north of the Cordero Mine which, with adjacent properties, produced over 115,000 flasks (76 pounds per flask) mercury from 1941 to 1972' Two other major mercury producers in the district have been the Bretz and Opalite Mines, located in southern Malheur County, Oregon, within 5 miles of the Oregon-Nevada line. Bretz and Opalite have produced about 14,800 and 12,370 flasks mercury respectively, from 1926 to 1965.1/

Jan 1, 1976

By W. R. VanSlyke

Scrubbing is gaining increasing recognition as a valuable tool in the treatment of Mesabi Range intermediate iron ores. In general, the earliest washing plants included log-washers in their various flowsheets. While log-washers certainly did impart a degree of scrubbing to the crude ore, such treatment bears little resemblance to the type of scrubbing being practiced today. At the time that these early plants were erected, only the true wash-ores were being processd. ("Wash-ores" are defined as crude ores in which relatively coarse chunks of almost completely liberated iron are found in a matrix of loosely-consolidated fine sand.) To treat ores of this type, sizing at approximately 65 to 100 mesh was sufficient to produce a merchantable concentrate. As crudes were being treated in which there was little "locking" of iron and silica, log-washers tended to disappear and large screens and classifiers took their place in Mesabi range flowsheets. The "screening and classification" type of flowsheet 'had its greatest usage in the 1945-55 period, generally speaking. During this same period, many operators found it necessary to supplement the "wash-ore" type flowsheet with heavy-media treatment.

Jan 1, 1959

By E. De Souza

Rockbursts and rockfalls cause very large safety and productivity losses in underground mines. One of the major unsolved problems of safe, economical rock support in underground mining has been that of maintaining anchorage during dynamic rock loading conditions or seismic related occurrences. It is recognized that the large displacements and high strain rates in excavation walls and underground structures cannot be countered by increasing the strength of stiff rock-reinforcing systems but must be accommodated by introducing yieldability into the support elements. This paper introduces a low cost yieldable support system which provides viable solutions to dynamic support loading. Such system should not only provide a feasible and more effective rock mass stabilization strategy but improve mine safety and reduce losses.

Jan 1, 1998

Spirals have become one of the most popular methods for treating fine coal. Unfortunately, spirals tend to produce an undesirably high specific gravity cut-point and often misplace significant amounts of coal and/or rock. In the present study, a process-engineering tool known as linear circuit analysis was used to identify problems with traditional spiral circuits and to suggest alternative configurations. These analyses indicate that a modified rougher-cleaner circuit incorporating a middlings recycle stream offers the best option for improving performance while maintaining a reasonable circulating load. In light of this finding, a full-scale test circuit was installed and evaluated at an existing preparation plant. Data obtained from the plant tests indicate that the new spiral circuit can simultaneously reduce cut-point and improve separation efficiency. Preliminary economic analyses show that the new circuit provides an attractive payback on the capital investment.

Jan 1, 1998

By J. Kou

In this paper the activation behavior of quartz using Ca(OH)2 as an activator in quartz reverse flotation with anionic collector was evaluated and their adsorption behavior was investigated using a variety of techniques. The adsorption of the collector KS-I on the surface of quartz with and without Ca2+ was primarily characterized using Quartz Crystal Microbalance with Dissipation technique (QCM-D), which is a high sensitivity in-situ surface characterization technique. The flotation performance was evaluated using a laboratory mechanical flotation cell at different process parameters such as pH, collector dosage, and Ca(OH)2 dosage. The anionic collector evaluated was a commercial fatty acid KS-I. The QCM-D data showed that the collector adsorbed on quartz more readily with Ca2+ as activator. The mass and structural property of the collector layer adsorbed on quartz surface at 2.16×10-3 mol/L of Ca2+, 0.3 g/L of collector and pH 12.0 have been studied using the technique of QCM-D. The chemisorption of the collector KS-I on the surface of quartz in presence of Ca2+ were also demonstrated by means of zeta potential, QCM-D and FTIR analysis.

Feb 23, 2014

By T. D. Arnold

The Barrick Bullfrog underground mine was established as an afterthought to the main open pit. As open pit ore dwindles, the underground mining becomes increasingly more important as an ore source, and to the overall economics of the project. This situation is similar to many other mines, and there is a strong move towards underground mining in the United States today. There are inherent problems in starting and operating underground mines in the shadow of any open pit operation, and at the Bullfrog there were several attempts at productive increases that were both successful and unsuccessful.

Jan 1, 1996

By J. Perlacia

"As the bulk handling sector continues its transformation to Industry 4.0, the mining industry, and its harsh working and environmental conditions, provides a perfect spot to study the feasibility of remote analysis and maintenance of the components used for bulk handling. The most important and expensive tools have been adapted to the digital era in recent years, from remotely controlled haul trucks to monitored conveyor belts.However, the big items of the installations rely on smaller parts that have been leftaside, mainly due to the difficultyof adapting them to the Internet ofThings (IoT).The paradigmatic example is the lack of monitored rollers, while all the other components of the conveyorbelt installations (the belt itself, motors, drums, etc.) were monitored some time ago. The main problem is that a failure of a single roller can cause the stoppage of the entire conveyor, due to possible damage to the belt. Thus, the implementation of an integral monitoring system of all the components of the conveyor is a must.The research and development department of ULMA Conveyor Components has been working since early 2012 on the development of monitored rollers, testing all the problems until their final installation in different demanding conditions, from the extreme heat in Australia to the freezing cold of Norway. All the tests have been done under actual working conditions, in real installations and have provided valuable knowledge in the identification of problems, their solutions and the final advantages of a roller monitoring system.Background and current stateThe malfunction of a single roller in certain conveyor belts can force the standstill of the entire installation until its replacement, due to the risk of greater and more expensive failures, such as a rip in the belt. In the case of a bulk handling installation, where a continuous supply of material is necessary, an unexpected stop of one hour could result in huge economic losses."

Nov 1, 2019

Computerized financial models can be used in all phases of the mineral industry from setting exploration targets to projecting profit plans for producing mines. In this presentation, I will use the example of an exploration company entering a new district to trace the application of financial models through the following intermediate phases. 1. Hypothetical analysis and strategy 2. First encounter of mineralization 3. Preliminary drill results - decision process 4. Feasibility studies 5. Post-feasibility negotiations 6. Producing mine 7. Acquisition of producing mines or mineral properties. I will conclude with a brief discussion of the mechanics of the financial models that we use at Wright Engineers Limited. As we progress through the seven phases, the availability and accuracy of the data will parallel the complexity and application of the financial models. However, the same basic financial models are utilized throughout the seven phases. I will begin by suggesting that the exploration group is somewhat autonomous and has the mandate to explore in Western Canada.

Jan 1, 1979

By Raymond E. Zimmerman

The cleaning of coal by the use of jigs is one of the oldest methods of separating coal from its impurities. Although in many situations jigs have been replaced by other methods, by far the largest percentage of coal today is still being cleaned by some form of jigs. Some piston- or plunger-type jigs are still in use throughout the world; however, the greater number are air pulsated, generally called the Baum jig, named after the original inventor, Fritz Baum of Germany. This standard jig, with slight modifications, has been in use for over 75 years. Up until recently, however, it has had certain limitations in obtaining the high performance and efficiencies required in modern coal preparation practice. TO improve its performance, some radical modifications have been made in its design and operation SO that there is now a Baum-type jig giving much higher performance in terms of capacity, efficiency and sharpness of separation- This new jig is called the Batac, and the purpose of this paper is to describe its characteristics and present data giving its performance in treating coarse and fine sizes of coal.

Jan 1, 1974

By L. L. Probert

A three-year project focusing on the depth profiling of respirable coal mine dust particles using scanning electron microscopy coupled with energy dispersive x-ray analysis resulted in the development of statistically classified particle-behavior models. The models depict the changing silicon fraction for 5-, 7-, 9-, and 11-keV accelerating voltages, thereby giving a clear indication of the nature of various types of particles. This paper will focus on the results for respirable quartz particles that occur in underground coal mines across the U.S. The relationship between the amount of surface-available quartz and coal seam rank is well established for Pennsylvania

Jan 1, 1994

By O. Lopez

"Stringent regulations and increased arsenic presence in ore bodies being exploited have created the need for cost effective and environmentally compliant technologies to remove selenium and arsenic from mine waters and metallurgical waste streams. Existing treatment methods have high life cycle costs and/or produce residues that, due to their unknown stability over the long-term, may represent future liabilities. This results in high compliance costs and uncertainties which negatively impact existing operations and projects in permitting. Selen-IX™ is a new ion exchange based process that selectively removes selenium from mine impacted waters down to 1 ppb while producing a stable inorganic iron-selenium product. Results of piloting completed on streams generated from coal and copper-gold deposits are presented along with preliminary equipment sizing and life cycle costs of full scale treatment. An example of a commercially available system for arsenic removal using sulphide precipitation is presented. The benefit of this treatment method is discussed based on recently completed technical feasibility assessment including laboratory testing and preliminary engineering design. INTRODUCTION Selenium Due to the chemical similarity between selenium and sulfur, selenium substitutes sulfur in many minerals that can be found in a wide range of deposits including coal, base metal, precious metal, phosphate, and uranium. One of the main environmental challenges facing the industry in North America today is related to the removal of hexavalent selenium, e.g. selenate, to ultralow levels, typically between 1 to 10 ppb, from large flows of often cold water containing less than 1,000 ppb of selenium. Recent studies commissioned by the industry identified biological selenium reduction systems as the best available technology. Although the biological selenium reduction process is commercially proven in certain applications to remove selenium to ultralow discharge levels, the technology has been primarily applied to relatively low and constant flows of warm water produced by the Flue Gas Desulfurization (FGD) scrubbers in the power generation industry. The wide spread adoption of this treatment method by the mining industry is hindered by high capital and operating costs associated with treating large flows of cold water, lack of data and knowledge about the long term stability of solid residues produced by this treatment, and limited capacity of biological systems to respond to sudden changes in flow and/or mass load of contaminants. Furthermore, it has been reported that reaching discharge limits less than 3 ppb could be a challenge and that polishing treatment for the removal of BOD and phosphate maybe required to avoid the impact of the biological treatment which requires organics and nutrients, on aquatic environment downstream of treatment plants. Alternate treatment systems are being developed to overcome and/or completely avoid some of the challenges of biological systems. One such treatment system is BioteQ’s Selen-IX™ process which is purely physico-chemical treatment system."

Jan 1, 2015

By G. Soni

A first principle flotation model has been derived from the basic mechanisms involved in flotation. The model consists of a series of analytical equations for bubble generation, bubble-particle collision, attachment, detachment, and froth phase recovery. The model can predict flotation from both hydrodynamic and surface chemistry parameters such as bubble size, particle size, energy dissipation rate, ?-potentials, contact angles (?), etc. The model has been validated in a series of laboratory batch flotation experiments, in which mono-sized glass beads are used as feeds. The experimental results are in good agreement with model predictions both in terms of grade and recovery.

Feb 23, 2014

High-pressure grinding rolls (HPGR) are an accepted, but continuously expanding, comminution technology. The copper industry has a growing need to process harder ores with progressively lower grades, more challenging metallurgy and increasing demand for efficient bacterial leaching applications. This has resulted in a major focus on HPGR use in a crushing circuit. If the industry is to increase leach extraction while lowering energy costs in high-throughput hydrometallurgical operations, HPGR will be of inherent significance. The following paper summarizes test work on copper leach ores utilizing the benefits of HPGR comminution, while increasing several critical metallurgical parameters. Based on the current work and previous investigations, it was found that HPGR comminution within a crushing circuit, in specific instances, can result in 2 - >10% increases in cop-per extraction. The tested variables are crush size, rock type and copper mineralogy dependence. Various other process parameters may also be optimized.

Jan 1, 2011