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By K. Witt, S. Steinlechner

In different nonferrous metal-producing industry sectors, the impurity element iron has to be removed from the process solution. Examples for the arising residues are jarosite or goethite precipitates from nickel or zinc production but also red mud from aluminum production. Regardless of environmental concerns, the material is landfilled in almost any case, although valuables such as indium, silver, nickel, or zinc are present in considerable amounts. Within the presented research, a low carbon dioxide emitting multi-metal recovery from such iron-containing residues by means of a selective chlorination extraction has been fundamentally evaluated by experiments but also by comprehensive thermodynamic calculations. The paper summarizes the thermodynamic fundamental concept exploited to separate the dominating iron matrix from the valuable elements and shows verification experiments in a lab size of several grams. Through thermodynamic calculations and smallscale experiments with pure metal oxides and sulfates, it has been proven that the metal chlorides AlCl3∙ 6H2O, FeCl3∙ 6H2O, and MgCl2∙ 6H2O are viable and effective reactants for chlorination. In trials with actual industrial iron precipitation residues from the zinc industry, especially, the use of MgCl2∙ 6H2O and FeCl3∙ 6H2O leads to high extraction rates for the investigated valuable metals Ag, Au, Bi, Cu, In, Pb, Sn, and Zn.

Nov 14, 2023

By Charles B. Escapule

The first successful heap leach of silver ores in the State of Arizona has been under continuous operation since early 1976 at the State of Maine Mine, two miles southwest of Tombstone, Arizona. The silver produced from leaching old mine dumps at this property vas the first in the Tombstone mining district to achieve a 999+ purity. While cyanide leaching of silver and gold ores is a time-proven accepted practice, a relatively new method of treatment called "heap" leaching was employed. Heap leaching is a comparatively inexpensive fast way to recover precious metals from low grade material.

Jan 1, 1981

By R. L. Grayson

As the total cost of labor has significantly increased over the past ten years, older underground mines have found it more difficult to compete- in a limited demand coal market. Many of the older mines were developed extensively into a reserve requiring a large number of workers to maintain and rehabilitate extensive track haulages and/or belt conveyor systems. Often, a large number of fans were required to maintain minimal airflows in areas where poor conditions and huge leakages prevail. This paper focuses upon problems which beset one such coal mine and projects undertaken to restore it to potential profitability.

Jan 1, 1986

By N. Arbiter

Fracture under low velocity free-fall and double impact, and under slow compression have been-investigated. The pattern of breakage and the size distribution of resulting fragments for sand-cement and glass spheres have been determined. Photoelasticity methods were used to simulate the stress distributions in free-fall impact in order to explain the observed patterns of breakage. Oblique fracture planes, occurring only in free-fall impact, develop along lines which coincide with the trajectories of principal compression as determined by mathematical analysis Breakage efficiencies for different modes of fracture were compared for both types of spheres. For the same specimen and loading system, static loading and low velocity dynamic loading induce geometrically similar stress fields resulting in reasonably similar fracture patterns and shapes of fragments.

Jan 1, 1968

By Yanan Zhang, Hongwei Deng, Feng Gao, Bo Ke

Recently, liquid carbon dioxide (L-CO2) blasting technology has attracted attention due to its good fracturing effect and safety performance, especially in coal seam permeability improvement. This paper analyzes the blasting effect of L-CO2 based on experiments and studies the fracturing mechanism from the perspective of stress wave action via theoretical analysis and peridynamic simulations. The results indicate that L-CO2 blasting achieves a good fracturing effect without forming a crush zone, and the loading rate and strength of the stress wave are key factors.

Jan 19, 2022

By T. Grounds, K. Singh, W. R. Reed, R. Cross, G. Ross, S. Klima, M. Shahan

"A 2nd generation roof bolter canopy air curtain (CAC) design was tested by National Institute for Occupational Safety and Health (NIOSH) at a Midwestern underground coal mine. During the study, the roof bolter never operated downwind of the continuous miner. Using a combination of personal Data Rams (pDR) and gravimetric samplers, the dust control efficiency of the roof bolter CAC was ascertained. Performance evaluation was determined using three methods: (1) comparing roof bolter operator concentrations underneath the CAC to roof bolter concentrations outside the CAC, (2) comparing roof bolter operator concentrations underneath the CAC to the concentrations at the rear of the bolter, and finally, (3) using the gravimetric data directly underneath the CAC to correct roof bolter operator concentrations underneath the CAC and comparing them to the concentrations at the rear of the bolter. Method 1 dust control efficiencies ranged from -53.9% to 60.4%. Method 2 efficiencies ranged from -150.5% to 52.2%, and Method 3 efficiencies ranged from 40.7% to 91%. Reasons for negative and low dust control efficiencies are provided in this paper and include: incorrect sampling locations, large distance between CAC and operator, and contamination of intake air from line curtain. Low dust concentrations encountered during the testing made it difficult to discern whether differences in concentrations were due to the CAC or due to variances inherent in experimental dust measurement. However, the analyses, especially the Method 3 analysis, show that the CAC can be an effective dust control device. INTRODUCTION Canopy air curtains (CAC) have been shown to be an effective respirable coal mine dust control for roof bolters in a laboratory setting with dust control efficiencies ranging from 14% up to 75% [Goodman and Organiscak 2001, Listak and Beck 2012, Reed et al. 2017]. Unfortunately, there is limited information on their effectiveness for controlling respirable coal mine dust in the field. On continuous miners, CAC dust control efficiencies ranged from 23% to 69% [Krisko 1975]. Two underground tests of the CAC on roof bolters demonstrated dust control efficiencies of 35% and 53% [Listak and Beck 2012] before problems occurred with operation of the CAC. Since the implementation of the new respirable coal mine dust limit from 2.0 mg/m3 to 1.5 mg/m3 (Code of Federal Regulations, 30 CFR 70.100, 2015), roof bolter CACs are becoming more commonplace in underground coal mines as a dust control tool to prevent roof bolter operator overexposure to respirable coal mine dust. J.H. Fletcher & Co. has been instrumental in delivering an effective design which incorporates the filter, blower, and canopy plenum seamlessly into the design of the roof bolter, resulting in a successful operational roof bolter CAC."

Jan 1, 2018

By A. Arik

Reliable ore reserve estimates for deposits with highly skewed grade disributions are difficult tasks to perform. Although some recent geostatistical techniques are available to handle problems with these estimations, ordinary kriging or conventional interpolation methods are still widely used to estimate the ore reserves for such deposits. The estimation results can be very sensitive to the search parameters used during the interpolation of grades with these methods. This paper compares the ore reserve estimates from ordinary kriging using several cases in which certain search parameters are varied. The comparisons are extended to different mineralizations to show the changing effects of these parameters.

Jan 1, 1990

By Raymond T. Moore

The Federal Coal Mine Health and Safety Act of 1969 (FCMHSA) begins with this statement: "Congress declares that the first priority and concern of all in the coal mining industry must be the health and safety of its most precious resource -- the miner; . . ." At the Federal level this responsibility is shared by the Department of the Interior and the Department of HEW. The health research and standard setting activities under the Act are largely the responsibility of the Department of HEW, and with the exception of Title 4, Black Lung Benefits, have been delegated to our Institute, which I will refer to henceforth as NIOSH. In addition, we bear certain joint responsibilities with the Department of the Interior. These include dust sampling and respirator approval. To complete the picture, the Department of Labor has recently assumed Black Lung Benefit respon¬sibilities from the Social Security Administration under Title 4 of the Act.

Jan 1, 1974

By Ralph Musick, Brian Briggs

The U1h Shaft Project is a design/build subcontract to construct one 6.1 meter(m) (20 feet [ft.]) finished diameter shaft to a depth of 321.6 meters (m) (1055 ft.) at the Nevada Test Site (NTS). Atkinson Construction was subcontracted by Bechtel Nevada(BN) to construct the U1h Shaft for the Department of Energy (DOE). The project consists of furnishing and installing the sinking plant, construction of the 321.6 m(1055 ft.) of concrete lined shaft, development of a shaft station at a depth of 297.5 m(976 ft.), and construction of a loading pocket at the station. The outfitting of the shaft and installation of a new hoist may be incorporated into the project at a later date. This paper will describe the design phase, the excavation and lining operation, shaft station construction and the contractual challenges encountered on this project.

Jan 1, 2001

By E. J. Berentsen

The Turquoise Ridge gold deposit is located near the Getchell Mine, 72 km (42 miles) northeast of Winnemucca, Nevada. The deposit is owned by First Miss Gold Inc. The host rocks consist of Ordovician and Cambrian age shales and limestones. They have been crosscut by the northeast-trending Turquoise Ridge shear zone and northwest-trending shear zones. Gold mineralization occurs at depths from 427 m (1 400 ft.) to 671 m (2 200 ft.), along the intersection of these structures. Large tonnage, flat-lying deposits occur where folded, favorable beds are intersected by the faults. The carbonate within the beds has been replaced with silica, pyrite and arsenic sulfides.

Jan 1, 1996

By Yosry A. Attia

One of the most significant advances in Mineral Processing in recent years, is the development of the selective flocculation technology. The technology is primarily aimed at recovering the mineral values from ultrafine ore suspensions. This is achieved by selectively aggregating the mineral particles in question to such size as to enable their effective separation from the suspension. Selective flocculation utilizes the differences in the physical-chemical properties of the various mineral components in the mixed suspension. It is based on the preferential ad- sorption of an organic flocculant on the particular solids to be flocculated, leaving the remainder of the particles in suspension. In order to understand the mechanics of this process, selective flocculation may be divided into four major sub processes; these being: ore slurry dispersion, in which all the particles are stably and uniformly distributed in the suspension with the individual particles being essentially separate; flocculant selective adsorption and floc formation; floc conditioning, which aims at obtaining flocs with desire properties for their subsequent separation and with minimum entrapment of dispersed particles; and floc separation from the suspension. These sub processes will be reviewed later in this article.

Jan 1, 1982

By William S. Fyfe

The world's biomass with its species-specific ability to concentrate metallic elements must provide one of the dominant concentration and transport systems for such elements. Given that about thirty elements are now considered bio-essential, for all these biomass may control their environmental behavior. Life appears to be present in almost all places where liquid water is present at temperatures near 100°C or below. In the surface environment a very large array of simple minerals are produced in living cells and such processes can lead to economic concentrations. Because of the specific nature of bioconcentration of elements, in all environments where biomaterials accumulate, interesting metal concentrations may occur or the molecular fragments from bio-degradation may allow specific metal transport and concentration. The scale of biological-inorganic interactions on our planetary surface is still inadequately appreciated.

Jan 1, 2013

By HONGWEI YANG, Lili Zhang

The oxidation behavior of copper smelting slag under non-isothermal conditions was studied by thermal analysis. The results indicate that the copper slag is mainly composed of fayalite ( Fe2SiO4) and magnetite ( Fe3O4). The oxidation behavior can be divided into two reaction stages with the increase in temperature; the first stage is the oxidation of fayalite to magnetite, and the second stage is the oxidation of magnetite to hematite. The two reaction stages cannot be strictly separated; that is, the reaction of fayalite is not complete, and magnetite has begun to transform into hematite. Based on the TG (thermogravimetric) curves, the ABS (Achar–Brindley–Sharp–Wendworth) differential and the Coats–Redfern integral methods were employed to investigate the oxidation kinetics of copper slag during the continuous heating process. The oxidation of fayalite into magnetite and amorphous silica phases occurs mainly in the temperature range of 673 to 1083 K. The activation energies calculated by the two methods are 193.69 and 195.52 kJ mol− 1, respectively. The reaction is consistent with Avrami–Erofeev equation, and the mechanism of oxidation is random nucleation and growth. The oxidation of magnetite to hematite occurs at 1083–1303 K. The activation energies are 308.79 and 328.77 kJ mol− 1, respectively. The mechanism conforms to the Jander equation and is controlled by the two-dimensional diffusion.

May 16, 2022

By E. Siami-Irdemoosa, S. R. Dindarloo

"Pareto analysis was used to investigate the failures database of a Hitachi EX1900 hydraulic shovel over one year of continuous operation. The hydraulic system and hydraulic links, hoses and piping were identified as the most critical system and subsystem, respectively. A three-parameter gamma distribution function was identified as the best fit for a probabilistic modeling of the time between failures (TBFs). This distribution was used in a Monte Carlo reliability analysis of the hydraulic system. Autoregressive integrated moving average (ARIMA), within the context of a time series analysis of the TBFs, was proposed as a viable alternative to the traditional technique of distribution fitting. The mean absolute percentage error (MAPE) metric was used to compare the two models. The MAPE value that resulted from the ARIMA was 66 percent smaller than that from the traditional technique in predicting the TBFs. Resumen ¦ Se usó análisis Pareto para investigar la base de datos de fallas de una pala hidráulica Hitachi EX1900 durante un periodo de un año de operación continua. Se identificó al sistema hidráulico y a los enlaces hidráulicos, mangueras y tuberías como el sistema y subsistema más importantes, respectivamente. Se identificó una función de distribución de tres parámetros gamma como el más apto para un modelado de probabilidades del tiempo transcurrido entre las fallas (Tabes por sus siglas en inglés). Esta distribución fue usada en un análisis de confiabilidad Monte Carlo para un sistema hidráulico. El promedio de movimiento integrado auto-regresivo (ARIMA por sus siglas en inglés), dentro del contexto de análisis de serie temporal de los TBFs, fue propuesto como una alternativa viable a la tradicional técnica de ajuste de distribución. Se usó el porcentaje de la media absoluta de error (MAPE) para comparar los dos modelos. El valor MAPE que resultó de la ARIMA fue 66 por ciento menor que el resultado obtenido con la técnica tradicional de predicción de TBFs."

Jan 1, 2015

By Thomas F. Martin

Contract 75-124-211 extends along the Chicago River from Roosevelt Road on the south to Ogden Avenue on the north. In addition a branch tunnel runs east from approximately mid-project ending near Lake Michigan. The contract was bid on December 14, 1977 with three joint-ventures submitting bids. Of these the joint venture of J.F. Shea Co., Inc. Walnut, California, (Sponsor), Peter Kiewit Sons' Co., Omaha, Nebraska and Shea Company and Associates, Walnut, California was low with a bid of $101,976,680.00. The MSD awarded the job to the Joint-Venture on January 5, 1978 with a scheduled completion date of January 23, 1983. The project consists of the following major items of work: (1.) A 25'-0" minimum diameter Construction Shaft, 220 feet deep (2.) 13,726 Linear Feet of 30'-0" Concrete lined Tunnel in rock (3.) 6,648 Linear Feet of 13'-0" Concrete lined Tunnel in rock (4.) Seventeen concrete lined Drop Shafts varying in finished diameter from 4'-0" to 12'-0", and each approximately 250 feet deep with chambers and connections to the tunnels varying from 100 to 1300 feet in length.

Jan 1, 1979

The visible portion of accounting-record keeping and preparation of financial statements-suggests a lack of sophistication and imagination. In reality, accounting is based on a large body of theory. Accountants philosophize, theorize, judge, create, and deliberate as a significant part of their professional practice. The subjective aspects that are so critical to current accounting practice, such as searching for truth and fact, judging what is fair presentation, and considering the behavior induced by presentations, are often overshadowed by the appearance of exactitude, precision, and objectivity that accompanies the use of numbers to express the financial results of the enterprise. * Fundamental accounting principles are hypothesized in the same manner as mathematical principles. These principles are justified by acceptability and intuition. Accounting theory is built upon these hypotheses, resulting in a coherent set of standards and rules. Although it does not specifically address every situation that may be encountered, this conceptual frame- work enables the manager or analyst to resolve specific situations. This framework also aids in the understanding and confidence in financial statements and ensures comparability between statements from different companies. This framework is referred to as "generally accepted accounting principles," or GAAP.

Jan 1, 1999

By F. A. Camisani-Calzolari

South Africa has adopted its own code for public reporting of Mineral Resources and Mineral Reserves in 2000. The South African Code for Reporting of Mineral Resources and Mineral Reserves (SAMREC Code or Code) (SAIMM 2000) is presented here in its local and global context. The main aspects of the Code are listed and elaborated upon. The Code has been written with the participation of the major South African stakeholders in the field including Government institutions, the legal confraternity and the mining industry. The Code is modelled on, and is 90% compliant with, the Australasian Code for Reporting of Mineral Resources and Ore Reserves (JORC Code) (AusIMM 1999). The paper also elaborates on the duties and responsibilities of Competent Persons signing off resource and reserve reports and on the listing requirements of the Johannesburg Securities Exchange (JSE), formerly the Johannesburg Stock Exchange, which has officially adopted the Code. The listing requirements were updated in 2000 to incorporate the SAMREC Code and subsequently in 2002, effective 2003. The ongoing obligations of the JSE for the exploration and mining companies are being compiled and are expected to be effective from early 2004.

Jan 1, 2003

By V. T. McLemore

Rare earth elements (REE) are becoming more important in our society. REE deposits are found throughout NM. Some REE past production (1950s), as bastnaesite, came from the Gallinas Mountains district, Lincoln County, NM. Several companies and the U.S. Bureau of Mines (USBM) have conducted exploration programs to identify REE potential. Four types of deposits are found in the district: epithermal REE-F veins, Cu-REE-F veins, REE-F breccia pipe and iron skarn deposits; all are associated with Tertiary peraluminous, alkaline to alkalic-calcic volcanic rocks. District zonation is defined by base metals (REE-F-Cu veins) that form center of the district, surrounded by REE-F veins. The magmatic-hydrothermal breccia pipe deposits form a belt partially surrounding the veins. Iron skarns formed at the top and edge of the trachyte intrusion and are likely the earliest stage of mineralization. In 1991-1992, USBM calculated an inferred resource of 0.487 million metric tons with a grade of 2.95% total REE. With the projected increase in demand of REE, areas such as the Gallinas Mountains district in New Mexico are being re-examined for additional REE potential.

Jan 1, 2011

By C. G. Janes, N. Finkelstein, L. M. Jr. Johnson

In May, 1966, the General Services Administration (GSA) announced a program to encourage additional domestic production of copper in the interest of national security. Upon learning of the copper production expansion program, Duval Corporation entered into negotiations with GSA for development of the Sierrita copper-molybdenum property under the program. Agreements between the GSA and Duval Sierrita Corporation, a wholly owned subsidiary of Duval Corporation, were concluded in 1967, with the Sierrita Concentrator beginning operation in 1970 at a designed capacity of 72,000 STPD. Subsequent additions and modifications have expanded capacity to 90,000 STPD. This property, located approximately 20 miles south of Tucson, Arizona, represents an investment including working capital of about $200 million. These funds were provided from an $83 million loan from GSA, repayable in copper valued at 38 cents per pound, $48.75 million of bank loans subject to U. S. Government V- loan guarantees, and Company capital contributions. Current general operating statistics for the concentrator are listed below: Ore Grade 0.32% Cu., 0.030% Mo. Daily Tons Milled 90,000 STPD Annual Copper Production 94,600 Tons Annual Molybdenum Production 15,000,000 Lbs. Annual Silver Production 1,135,000 Ounces

Jan 1, 1976

Many investigators believe that column flotation cells offer significant advantages over standard mechanical machines for the flotation of fine particles. However, because of their unique design and operation, conventional techniques for flotation cell scale-up and design cannot be applied to columns. In an attempt to help alleviate this problems a population balance model based on first principles has been developed for fine particle flotation in a column. Two different terms have been considered in the model, i.e., transport and rate. Transport terms, incorporating fluid flow and bouyancy, are used to describe the movement of air bubbles, unattached particles and bubble-particle aggregates along the length of the column. Rate terms, which describe the bubble-particle attachment process, have been derived from first principle considerations. Because the model is based on first principles, it can be useful for the design, control, optimization and scale-up of column flotation cells.

Jan 1, 1987