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By Bruce L. Bryson

In the past decade a principal growth area in refractory technology has been the development and use of extra high alumina refractories. The refractories user is asking for, and is prepared to pay for, higher purity, more dense materials with longer life, less maintenance, and better dimensional tolerance to meet the exacting demand of high output processes. High alumina and bauxite refractories are being used more and more to keep pace with the demand for guaranteed performance. The steel industry, for example, is starting to place great reliance on these products. A unique material now available with all the requirements for extreme purity and density is tabular alumina, already proving itself in many refractory applications.

Jan 1, 1973

By P. D. Georgescu

Gold, like no other metal, has a fascinating and special place in the world. It is used in a range of every day applications essential to modern life. Gold has long been considered the most precious metal in the world. Gold is used mainly for making jewellery as well as for dentistry, adornments on building and artistic expression. For thousands of years it has been used as an ornament of kings, a currency and standard for global currencies, and more recently, in a wide range of electronic devices and medical applications. Gold?s many unique properties have secured in a central role in history and human development. Today, more often than not, gold is extracted from ores. It occurs in vein and alluvial deposits and is often separated from rocks and other minerals by mining and processing operations. Some of these processes cause environmental concern (cyanidation, amalgamation, roasting). Besides primary gold ore resources, a series of secondary resources can be taken into account and processed for gold and silver recovery. There are two main types of waste produced. The first type is process waste, which includes tailing consisting of processing residues and waste rock. The other type is refuse from other different processes and recyclable materials. Among other secondary resources and/or by-products containing precious metals, which have been studied some processes and technologies with low ecological impact are presented in this paper. Heaps and tailing ponds resulted from gold-bearing ore exploitation and processing, refractory gold-bearing pyrite concentrates, slag resulted from electrolytic slime melting, gold-bearing chlorous slime are taken into account. In order to establish environmental friendly technologies for precious metals recovery from these secondary resources, laboratory experiments have been carried out on a pilot scale and in some cases on semi-industrial scale by applying specific technological processes, namely hydro-gravitational concentration, bio-oxidation, non-ionizing electromagnetic radiation (microwaves), solubilization without utilizing cyanide and gold recovery by ion-exchange resin. This paper presents the research results, technological principles as well as the possibilities of applying combined processes in order to treat different secondary gold-bearing resources.

Jan 1, 2006

By Zhang Zhitie

The limitations in mechanism research of mineral comminution in the past and the basic features of the comminution process have been analyzed. Two kinds of catastrophe model, i.e., cusp model and swallowtail one in the mineral comminution have been put forward. The dissipative structure of the mineral comminution: entropy production rate, extra entropy, extra entropy production and system stability has been discussed. The physical nature of the behavior that an old structure was destroyed and a new one was produced in the mineral comminution process has been brought to light.

Jan 1, 1995

By Huo Zuzhao

The main feature of caving methods is to draw ore from the overlying waste rock. Research on the movements of ore and waste plays a very important part in reducing ore loss and dilution and raising the economic benefits. This paper gives the basic theory of computer simulation of ore-draw, exposses the physical significance of mathematical model, puts forword a new formula of similarity characteristic value, brings forth a method of adjusting similarity, introduces the major functions of the simulation program and describes the ore draw control and stope parameter selection through computer simulation.

Jan 1, 1986

By J. -C. Roegiers, M. Thiercelin

Accurate toughness determinations are difficult to achieve in the case of soft or heterogeneous rocks. The existence of a large process zone ahead of the crack tip makes the determination of the apparent toughness crack length dependent, in the case of subsized specimens. In order to use practical size specimens, the authors propose a new toughness test, the Modified Ring Test, which pre- vents a largely developed process zone to form ahead of the crack tip. This test has also the advantage that its geometry is core-based. Numerical and experimental results are discussed.

Jan 1, 1986

By C. A. Fleming, R. G. Williamson

Process development for Eskay Creek began in early 1990 at Lakefield Research, and was initially focused on producing a high-grade/high-recovery concentrate for sale. Owing to the significant base metal sulphide (Cu, Zn, Pb) content of the ore, such a product would have made an attractive feed to a copper smelter, while a gravity and/or flotation flowsheet would have circumvented many of the environmental permitting problems that were anticipated. In the event, it was found that neither gravity nor flotation (nor even a combination of the two) was able to produce a discardable tailing and, in late 1990, attention shifted to the development of a hydrometallurgical flowsheet.

Jan 1, 1995

By I. Tsolas

Sustainable development is becoming increasingly more important for the mining industry and therefore mining companies should be able to measure their progress towards sustainability. Greek Public Power Corporation (PPC) S.A. is a company which produces lignite in open cast mines in Western Macedonia and in Peloponnesos. The present paper uses operational data kindly offered by PPC S.A. to derive sustainability indicators by means of Data Envelopment Analysis for three large scale lignite open cast mines of PPC (i.e. Main Field, Kardia Field and South Field mines). It also examines three environmental parameters related to the contribution of these mines to sustainable development; namely, the annually produced volume of waste masses, the annually produced quantity of ash from the lignite combustion and the annual volume of pumped water. The calculated sustainability indicators were keeping constantly better during the last years of the different periods for each one of mines studied here, showing that the mines met their goals from both economic and environmental aspects during the last years of their operational periods studied. The contribution of open cast lignite mines studied here to sustainable development can be monitored by the derived indicators analyzing annual mine operational data. The derived indicators can serve as tools to detect where improvements can be made, though another potential use of these indicators can also be during the preparation of feasibility studies or environmental impact studies using necessary benchmarking data.

Jan 1, 2007

By Wilfred Walker

A working hypothesis is presented herein mineral belts are split as all world oceans opened. Rather than plate tectonics, expansion is favored as the most recent expression of the sequence of convecting systems in the Earth's mantle. Throughout the geological record this sequence has produced similar mobile belts. This similarity lends itself to both stratigraphic classification and the theme of mineralization in mobile belts demonstrated by Y. A. Bilibin. Crustal evolution should, therefore, serve as an important guide in understanding Pacific mineral belts.

Jan 1, 1982

By Anthony Delvescovo, Gregory F. Aluce, Joseph A. Sopko, Lyle C. Smith

Construction of a 13m shaft through approximately 100m of water bearing soils and another 100m of bedrock was attempted using the Slurry Diaphragm Wall Method with a combination of deep dewatering wells. During excavation within the slurry wall, unexpected groundwater inflows occurred in a structure of loose silty sands. Artificial ground freezing was selected as a remedial method to seal the leaking slurry wall, and as a primary excavation support and groundwater control method for the 30m of overburden material below the base of the wall. Design of the ground freezing system required analysis of both the structural requirements of the unsupported soil, the frost effects against the existing slurry wall and the groundwater control in the area of the breech in the wall. These design procedures are summarized, and construction and excavation techniques and corresponding schedules compared in this paper. Advanced drilling techniques, ground freezing quality control and general contractor procedures for efficient shaft construction are discussed.

Jan 1, 1993

By J. E. Osmanski

This semantically ambiguous title purports to describe an examination of the question of automation and its effect on the industrial worker. More explicit titles might be "Painless Automation" or "Mechanization without a Sting" or, if I may steal a few phrases from the title of a recent interview Pith John L. Lewis, "More Machines, Fewer Men -- Is the Union Happy About It?" Automation has become the biggest ?scare word? for many industrial workers and their unions since "wage stabilization.? "To many a union orator," reports TIME of January 4, "automation is the sinister business of eliminating jobs." TIME might better have phrased this description by saying that many unions regard automation as the attempt to eliminate not jobs, but workers, The recent steel dispute was hung up for so long primarily because of the problems evolved of increased job efficiency through automation and job changes. Everywhere today there is heard the cry of our need for maintaining full employment within the context of an expanding economy echoing against the sheer reality of automation's displacement of thousands of workers through a rapid acceleration of productivity.

Jan 1, 1960

By H. W. Gussmann, R. G. Rohrs, E. van der Merwe

Salinity in Effluents carries a high penalty as a result of toxic­ity, corrosion, limited re-use potential, scaling and environmental impact. Although the high TDS, such as Calcium sulfate, other than metals are still being dealt with a low key non issue basis, they are receiving more and more attention from regulators. Traditional solutions to solve these problems are costly and inefficient and create therefore severe constraints on the prof­itability of mining operations and out-price in general the finan­cial resources for environmental clean up operations. Going up the technology versus cost curve the most econom­ic solution to pollution is dilution but which is difficult in a coun­t1y shoti of water. If this can't be done, the second best, at least in sunny areas, is, to pump the whole effluent on a tailings dam for evaporation. Depending on the contaminants, one may have to pond the efflu­ent to avoid re-dissolution and seepage into the ground. The next most common solution to pollution is the addition of lime to remove and concentrate any dissolved metals and then dump the product, hidden in a mass of gypsum in a convenient place. Again ponding may be required to avoid ground pollution. However the treatment costs start to rise steeply if it is not allowed to discharge the limed overflow solution because of its high calcium sulphate content. Further treatment is then required in the form of high cost and high tech membrane process tech­nology such as reverse osmosis or dialysis or even mechanical driven evaporation.

Jan 1, 1998

By Hazal Melis Aytac, Lana Alagha, Fardis Nakhaei

Gallium (Ga) and Germanium (Ge) are essential strategic elements that are extensively used as semiconductors in many technological fields. Owing to their essential uses and supply disruption, Ga and Ge are deemed critical by the U.S. They are typically found as substitutions or inclusions in zinc minerals. However, their distributions within zinc minerals are not well understood. To address this, trace element and mineralogy analyses of representative samples obtained from an old high-zinc-grade tailing were performed using various qualitative and quantitative techniques. These techniques included Inductively Coupled Plasma Mass Spectrometry (ICP-MS), Tescan Integrated Mineralogical Analysis (TIMA) with Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD). Moreover, bench-scale froth flotation tests were conducted to enrich zinc minerals, the major hosts of Ga and Ge, using PAX as a collector, Na2S as a sulfidizer, Pb(NO3)2 as an activator, and MIBC as a frother. Comprehensive characterization analyses of the flotation products showed significant enrichment of Zn, Ga and Ge in the flotation concentrates.

Feb 1, 2025

By Paul Hosford, B. Thrall

There has been a surge of exploration activity and interest in mineral properties located in cold Northern climates, with gold and copper properties as the two most attractive targets. There are already a number of mining operations located in the Arctic, for example, Red Dog, Polaris, and Lupin, all located in the Canadian Arctic. The logistics of sustaining operations, the engineering design and construction methods for such inhospitable regions are now relatively well understood. However, at least three of the proposed new mines in the Yukon Territory, Canada are designed to be heap leach operations. Rescan Engineering has recently completed Feasibility studies for two heap leach operations in the Yukon, one of which, the Brewery Creek Mine, is now in operation. The purpose of this paper is to explore some of the engineering and operating concepts that have been developed to make heap leaching an appropriate process method for gold recovery in a cold climate. Many of the readers will be familiar with the general and specific details of heap leaching, and it is not the intention of the authors to deal with any of the established "do's" and "don'ts" that have been addressed in numerous previous papers, but only with those pertaining to cold weather operations. This paper also examines these design concepts in specific relation to the results of the first winter's operation at Brewery Creek Mine, the first "far" North heap leach operation.

Jan 1, 1997

"In the mining industry, high-level commitments to adopt sustainability have been made at the corporate levels of mining companies, but there continue to be problems when attempts are made to adopt these high-level sustainability aspirations and translate them into appropriate targets and methods at the more-specific operational level. The integration of sustainability principles into day-to-day minerals processing operational decision-making processes has unique challenges that are not addressed adequately by current tools and methodologies. A proposed methodology to achieve integration of sustainability at the operational level will direct the systematic and rigorous identification and characterisation of sustainability issues in an operation. The methodology allows different approach strategies for assessment, comprehensive accounting of sustainability indicators and has the ability to identify sustainability issues which may have significant business implications that cannot be identified using traditional analysis processes."

Jan 1, 2011

By J. Bouchard, V. Aubé, A. Desbiens, R. del Villar

The metallurgical performance of column flotation is determined by the concentrate grade and recovery. Although the former can be continuously measured using an on-stream analyzer, the latter must be estimated by a material balance calculation based on seldom verified steady-state assumptions. Consequently, the automatic control and optimization of flotation columns should be performed using secondary variables having a strong influence on the metallurgical performance, such as froth depth, gas hold-up or bubble surface area flux and bias. The aim of this paper is to present a method to get froth depth and bias measurements using virtual sensors. Fractional factorial experiment design for the neural network calibration of the bias sensor, pilot plant results, and eventual industrial applications – including the possibility of achieving effective real-time optimization from bias and froth depth measurements – will also be discussed.

Jan 1, 2003

By Philip U. Santacroce, James H. Meinholz

INTRODUCTION The Milwaukee Metropolitan Sewerage District (MMSD), is a special purpose sub-regional agency that provides collection and treatment services for sanitary wastewater for an area of 420 square miles (1088 km2) in 27 municipalities in the Milwaukee, Wisconsin metropolitan area. During its almost 75 years of existence, it has constructed 464 km of intercepting sewers, the majority in tunnel, and two sub-regional secondary wastewater treatment plants. The present program, the $1.7 billion Milwaukee Water Pollution Abatement Program, was started in 1977 and developed from ongoing internal planning, the Federal Clean Water Act and court judgments. Elements of the Program include improvement and expansion of the two treatment plants; rehabilitation of older in-place sewers; building new interceptors and relief sewers and providing capacity for high volume storage in approximately 32 km of deep, large diameter rock tunnels; reducing combined sewer overflow; and disposal/utilization of the solids that remain after the treatment process. The construction phase of the Program accounts for $1,105,900,000 within 335 separate construction contracts, 211 let to date, and covers a span of 15 years, starting in 1979 and running through 1994. Conveyance System construction cost is estimated to be $650,000,000 or about 60 percent of the total. Through December 1986, in terms of dollars, the total construction program is about 38 percent complete with Conveyance at 34 percent complete.

Jan 1, 1987

By Z. Eisenstein, H. Heinz

INTRODUCTION Contemporary underground transit systems often require cross sections which are not adaptable to shield tunnelling. Due to the frequently large dimensions of these cross sections, which are normally situated at shallow depths and in soft ground, full face advance is not feasible because of ground control and construction requirements. Ground deformation and face stability are controlled by "staged excavation", which consists of sequentially driving smaller, specially arranged, individual headings hence avoiding full-face excavation. Shotcrete is normally used for initial support and these tunnels are frequently described as applications of the New Austrian Tunnelling Method (NATM). Figure 1 illustrates the relative size of large cross section tunnels with respect to conventional shield tunnels. Within the scope of this paper, 'large' cross sections are defined as those whose continuous (i.e., without intermediate pillar support) cross sectional excavated area exceeds 60m2. This definition includes most double track highway, railway and subway tunnels, subway stations and some single track railway tunnels. Excavation schemes which have been more frequently used for continuous cross sections (i.e., with no intermediate pillars) are presented in Figure 2. This classification is an extension of that presented previously by Eisenstein et al. (1986). The symbols used for classifying the excavation schemes are formed by the letter T (for "type"), followed by a number, which represents the number of excavation stages fully embraced by a shotcrete ring, termed "cells" by Lessmann (1986). The numbers inside the cross sections in

Jan 1, 1989

By C. E. Tackett

The Greenwich Collieries Co. is a subsidiary of the Pennsylvania Mines Corporation, and a wholly owned subsidiary of the PP&L Co. which serves the northeastern portion of Pa. PP&L annually consumes about 11 million tons of coal per year and is the largest consumer of both bituminous and anthracite coal on the eastern seaboard. Development work for Greenwich started in 1969. The coarse coal plant was constructed in 1970, with the raw fines bypassed. This worked very well for our requirements at that time; however, the Greenwich mining plans were extensively changed, longwall mining units were installed and low coal was encountered, resulting in dirtier coal, a finer coal and an ever increasing ash in the shipped product. All this demanded a more efficient ash removal process for the fine coal fraction. In 1971, the Pennsylvania Department of Environmental Resources and the Federal Environmental Protection Agency were pushing for the now stringent sulphur emission limits at our power plants. The Greenwich Mine coal reserves contained large quantities of 3.5 to 4% sulphur along with some low sulphur reserves. It was, therefore, essential that any new plant have the capability of efficient sulphur removal to meet the Pennsylvania Department of Environmental Resources and the Federal Environmental Protection Agency required limits. To meet these limits our design would have to be capable of producing a product of 2.0% sulphur or less.

Jan 1, 1977

By Peter S. Schneidkraut

This paper will discuss the Final Tunnel Linings which were placed in 6700m of a 2.32m inside diameter precast concrete lined interceptor sewer tunnel in Staten Island, New York. Two methods were employed to install the final tunnel linings. One method involved forming and placing a polypropylene fiber reinforced concrete cunnette invert, followed by an arch pour. The second method involved the jacking of reinforced concrete pipe into the tunnel, followed by a low density cellular concrete backfill grout. These two methods will be described and compared.

Jan 1, 1993

By Samuel S. Adams

Economic concentrations of potassium are essentially limited to thick, stratigraphic sections of marine evaporites. These deposits were precipitated through the evaporation of sea water in restricted epicontinental seas or in grabens related to continental margin rift systems. Following deposition the deposits were subjected to diagenesis and varying degrees of metasomatism and structural deformation. The origin and characteristics of potash deposits are easier to study and interpret than those of most ore deposits because the phase chemistry of the salt systems is known and the approximate composition of the ore-forming fluid (sea water) can be inferred with confidence. It is particularly helpful that the temperature and pressure of deposition approximated that of present earth surface conditions and the pertinent mineral assemblages can readily be duplicated in the laboratory. The study of these comparatively simple salt deposits provides examples of the practical advantages of understanding the genesis of an ore deposit. These observations, in turn, illustrate the importance of pursuing research on the more complicated magmatic, hydrothermal, and ground-water systems as a means to the more successful exploration for and exploitation of the deposits they have produced. It is the purpose of this paper, therefore, to discuss certain aspects of salt deposit geology as they contribute to exploration and mining through some understanding of ore formation. References to field examples and chemical relations in the salt systems are brief. All examples are more fully discussed, however, in the references cited.

Jan 1, 1970