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By Garrett R. Hyde, Aleksandar Stojsic

Introduction Economic pressures in the international marketplace have spurred advances in almost every facet of flotation. New developments have occurred in flotation chemicals, flotation machines, and in the application of automated process control technology to grinding and flotation. Many of these advances are the results of concerted efforts to apply the knowledge obtained from basic flotation research over the past 15 to 20 years, to develop industrial technology for the more efficient separation of sulfide minerals in real ores. Mining company executives and equipment manufacturers are being called on to make decisions for incorporating some of this technology into present operations. This discussion is limited to two developments now at the stage of being engineered into industrial scale operations. They are control of the electrochemical environment or redox potential of the slurry, and control of bubble size in column flotation. Potential economic impacts are noted. Froth flotation Froth flotation makes use of differences in the surface properties of finely ground minerals to obtain separation. If the mineral surface is water repellent, the mineral particle will stick at the air-water interface of a bubble and float. If a mineral surface is not naturally water repellent, a chemical collector is added to the slurry to make it so. The collector must adsorb on, and make water repellent only the mineral to be recovered, not the gangue minerals. To achieve this degree of selective adsorption, chemical modifiers may have to be added to the slurry. Modifiers include pH regulators, activators, and depressants. Electrochemical control One of the most significant developments in recent years in the area of mineral processing technology is the recognition that collector adsorption of sulfide minerals is an electrochemical process. Consequently, flotation of these minerals depends on the electrochemical or redox potential of the system. Many of the modifiers used to control various flotation processes are actually potential controlling reagents. For example, the role of well known depressants, such as cyanide, sodium hydrosulfide, and sulfur dioxide, is essentially to

Jan 7, 1987

By Jonathan M. Pachter

Introduction The Bailey mining complex is located in Greene County, PA, in the Talley Run valley. It includes two Pittsburgh No. 8 seam deep mines (Bailey and Bailey No. 2), a coal preparation plant, and two refuse areas. Clean coal is shipped from the complex by way of a 24-km (15-mile) rail spur. It con¬nects to the Monongahela Railroad in Waynesburg, PA. In early 1981, Consolidation Coal Co. (Consol) began a permitting effort aimed at building the mine. Construction began in Dec. 1981, less than six months after the first application submittal. Clean coal was produced by the Bailey preparation plant in Sept. 1984. Several factors allowed quick permitting at Bailey. Effective project planning, including early formulation of a project planning team, and identification of red flag issues helped. So did innovative responses to environmental questions, and development of environmentally sound project designs. Forming a project planning team Consol management decided that Bailey mine construction had to begin in late 1981. A project permitting team was immediately formed to see that this goal was achieved. Team members included a project manager and personnel from Consol's engineering, environmental, and operating departments. Communications among all team members was crucial in obtaining the various state and Federal environmental permits. All project permitting team members participated in weekly meetings during application preparation. Discussions at these meetings ranged from recent public contacts, to application content, to environmental design considerations. Establishing a project manager was critical to the team's success. The project manager was responsible for seeing that permit acquisition, facility construction, and operation of the mining complex proceeded on schedule. The project manager had the final word, mediated disagreements, and frequently served as project spokesman to the public. Identifying red flag issues Red flag issues are those environmental factors with the most potential for delaying the schedule or stopping the project. The first red flag issue identified was organized local opposition. This opposition had completely derailed a US Soil Conservation Service proposal to build a multipurpose dam on Enlow Fork, a short distance

Jan 9, 1985

By J. J. McDougall

The Windy Craggy copper-cobalt-bearing massive sulfide lies in the Tatshenshini map area of northwestern British Columbia, where British Columbia joins Alaska and the Yukon. The area is covered with numerous glaciers and ice fields that mask geologic detail and hamper ground access. In 1957, Ventures Ltd., the predecessor of Falconbridge Ltd., undertook a reconnaissance of the area using a float-equipped Supercub. At that time, large lakes and glaciers were unnamed and little was known of the geology. The prospecting team was led by J.J. McDougall with Stan Bridcut as pilot-prospector. Prospecting was directed at the St. Elias Mountains between the rich Kennecott copper deposits to the northwest and the Maid of Erin silver-copper mine on the Haines Road, BC. Reconnaissance flying in 1957 and early 1958 eliminated vast segments of the Kennecott-Haines Road terrain as being too inaccessible for mining. In 1958, the Supercub landed at an unnamed lake and the terminal moraine of an unnamed 12.9-km (8-mile) long glacier was prospected. The lake was called Tats Lake and the glacier named Tats glacier (short for Tatshenshini). Float of sulfide was found in the moraine. Follow-up investigation along Tats glacier led to the discovery of several small sulfide deposits and these were staked. Prospecting active glaciers in this area can be complicated because of drainage capture by eroding valley glaciers. Glacier capture resulted in the float from one mineralized area being deposited at different times in three widely separated moraines. Float of the Windy Craggy deposit, therefore, occurs along the course of older glaciers and at the base of the currently active ones. The problem of sourcing caused much additional Supercub reconnaissance. It is interesting to note that about 40 geographic names were given various features in this unmapped portion of the St. Elias Range, and these names were ultimately officially adopted.

Jan 1, 1991

By Olivier Martin

In busy and historic cities, traditional open box metro stations are becoming outrageously difficult, unacceptable for the citizen and uneconomical. Hybrid stations provide an interesting alternative. In-house experience of Gautrain (South Africa), West bay (Qatar), Cairo line 3A (Egypt), and Melbourne (Australia) all aim to reduce disturbance to the city and its inhabitants during construction. Constructed in rock or in deep soil under water table, they take advantages of the latest construction techniques from cement grouting to freezing, and from traditional excavation of cavern to large tunnels constructed by sophisticated tunnel boring machines (TBM). Today, they form the ultimate construction challenge.

Jun 13, 2021

By S. S. Szoke

The concrete masonry industry, represented by the National Concrete Masonry Association has significantly expanded its markets since the industry's inception. The concrete masonry industry has developed and refined concrete masonry units by producing a variety of quality products on automated machines. In the sixties, architectural concrete masonry units gained popularity. In the seventies, the concrete paver market expanded. In the eighties, segmental retaining wall units became popular. The industry continues to research and develop new products and applications for concrete masonry to satisfy the needs of designers, specifiers, installers and owners. Both existing and innovative technologies in the concrete masonry industry are discussed.

Jan 1, 1993

By S. Vijayan

Despite the limited demand for rare-earth elements, as well as yttrium and scandium, in conventional applications, the emergence of ne~ high-technology applications such as supermagnets, lasers and superconductors is expected to result in significant demand for some of these elements. This paper examines the anticipated applications and demands for rare-earth elements over the next decade and their implications on the utilization of available resources. Process methods for the recovery of rare-earth elements from conventional and unconventional resources are reviewed in the context of their growing demand. Challenges facing the industries in meeting this opportunity are also discussed.

Jan 1, 1988

By S. A. G. Poppen

The lining of a mine shaft is one of the most important considerations in the planning and operation of an underground mine. Generally, the function of a shaft lining is to preserve the shaft opening in a manner compatible with the expected mine life and -the other shaft operations. Where shafts are the only means of surface access in a mine, they also serve a critical function for the safety of the entire underground operation. Routine repairs and maintenance work on the shaft linings are only possible in stable strata with only minor interruptions to the shaft operations.

Jan 1, 1988

By Hans von Michaelis

Welcome to RANDOL GOLD FORUM 88. It is clear from the list of delegates and speakers that this conference will lead to excellent discussions of the latest developments in this fast-moving industry. Less than a year ago Randol International Ltd. published an eleven-volume report titled "Innovations in Gold and Silver Recovery - Phase 111". In the short space of time since then, many new developments have been noted, many of which will be described in this Forum. I believe that some of the more significant innovations currently under development are those that address the following:

Jan 1, 1998

By G. Danko

Ventilation and refrigeration for mine climate modification, contributes significantly to the operating costs of a deep hot mine. Mine climate simulation programs can be used to minimize the impact of these costs. There are several computer codes available including CLIMSIM?, to assist in this work. Whichever simulation program is used, it is the mine ventilation engineer who must supply the input data. This paper raises and answers the following question, namely: what accuracy is required of the basic input parameters, in order for a certain precision to be obtained in the predicted air temperatures? In the first part of the paper a new approach is described to estimate the dry and wet bulb temperature of the airflow, either in a dry or wet roadway. The calculation procedure allows an arbitrary temperature change with time, using Duhamel's superposition solution. Matrix-vector representation is applied to simplify the computational structure. In the second part of the paper the sensitivities of the dry and wet bulb air temperatures are analyzed to the changes of the rock thermo-physical properties, the heat transfer coefficient and the wetness factor.

Jan 1, 1988

By Tim Haldane

Cyanide consumption at the Gold Fields Operating Company Mesquite Mine has shown a steady decline since the heap leach operation started up in 1986. A series of solution strength changes and equipment design improvements have resulted in a reduction of sodium cyanide consumption from peak levels above 1.0 pounds NaCN per ton of ore in 1986 to current levels at 0.15 - 0.20 pounds NaCN per ton of ore. Aside from the obvious cost benefits associated with this reagent consumption reduction, the property has also enjoyed environmental benefits which go hand-in-hand with these cost savings.

Jan 1, 1990

By M. S. Hunter, Al Bishop

In 1994, Lone Tree Mine invited Hunter Hawk to participate in a problem-solving arena at their mine located in Valmy, Nevada. Lone Tree was experiencing consistency problems with autoclave valve component quality and delivery. Based upon a prior working relationship at Homestake Mining Company's McLauglin Mine, located in Lake County, California, both customer and vendor enjoyed a measure of rap­po1i and trust - the keys to problem solving communication. This paper is an overview of the problem solving process that has contributed to Lone Tree's excellent record of 95 per cent autoclave availability since 1995.

Jan 1, 1998

The bromine review did not arrive in time for publication in the June issue. Bromine production in the United States during 1992 amounted to 171 kt (376 million lbs), a 453-t (I-million lb) increase from 1991. Data compiled by the US Bureau of Mines indicates this increase was due mainly to greater exports of elemental bromine and bromine derivatives (flame retardants). Exports increased despite the economic slowdown in Europe and Japan. The United States remains the world's largest bromine producer, with about 42% of the total. Israel is ranked second, followed by the United Kingdom, the former Soviet Union and Japan.

Jan 1, 1993

By Len H. Steele

To date VMD have designed, built and supplied nine autoclaves to various mining companies in Canada, the US, and Papua New Guinea. Initially, completely fabricated and lead lined units were shipped. The logistics of Placer Dome's Porgera PNG Project necessitated fabricating and lead lining each autoclave in five sections for transportation to site, each piece weighing approximately 30.5 tonnes. Support equipment such as turning rolls, automatic and manual welding machines had to be set up on site to facilitate assembly of these units which was a challenge in planning. This on site erection programme was completed in three months.

Jan 1, 1992

By Boris V. Vlasenko, Vadim P. Potapov, Gennady I. Gritsko

In this paper we consider the elements of an information geomechanic monitoring system which is used in computerized mine planning and mining operations control. The automated sys tem is a technical means of geomechanic monitoring, as a complex system of regulated observations, estimation and prediction of changes in geomechanic state of rock mass and workings during underground mining of coal deposits. Geomechanic monitoring at coal mines and the automated system execute data collection, analysis and calculations of geomechanic situation in the panel during planning, development and carrying-out of mining operations for ensuring geotechnical stability of underground mining.

Jan 1, 1996

By Liang Ruilu, Guo Lihua

In light of the properties on process mineralogy of the old tailings in a certain copper mine in the People's Republic of China, a new process of combined reagent and stepwise flotation is applied in which the flotation of copper sulfides is followed by the flotation of copper oxides. Recoveries of copper and associated gold and silver have been greatly increased. The tailings obtained were subjected to the gravitational separation-magnetic separation process to recover iron minerals. Tailings from iron separation are taken as fillers and sent to the pit underground. Thus, the secondary resources are comprehensively utilized.

Jan 1, 1995

By P. Todd, K. Dever, P. S. Mills, A. A. Campoli

Resin bolt performance is dependent on the size of the resin annulus, i.e., the difference between the hole and bolt radii. The majority of the millions of resin roof bolts installed each year in the United States employ an annulus of 3.175 or 4.775 mm (0.125 or 0.188 in.). Short encapsulation pull tests with resin annuli of 3.175 and 2.413 mm (0.125 and 0.095 in.) resisted an average of 0.08 t/grouted mm (2.25 st/grouted in.) with no significant variation. Resin loses to simulated fractures increased as annulus size decreased.

Jan 1, 2003

By L. M. Bigler, J. L. Dobra

With the passage of Mexico's Mining Law in 1992, the tax treaty with the US in the same year, and the passage of the North American Free Trade Agreement, gold mining for non-Mexican mining companies in Mexico has changed dramatically. The statutory changes have created an opportunity for non-Mexican precious metals' producers to own 100% of a Mexican gold concession. This paper examines the financial feasibility of a hypothetical gold mine and processing plant in Mexico. The analysis includes the operational consequences of the recent weakness of the peso, as well as tax and employment issues.

Jan 1, 1996

By Terence G. McCusker

Precast concrete segmental tunnel linings have been used since at least 1903. More serious attention was devoted to them in England during the World War II steel shortage and they have become increasingly common since that time. They are now coming into common use in the United States, especially as primary linings for soft ground tunnels and for rock tunnels in poor ground, although they have also been used as final lining, especially in rock tunnels. The developmental logic, design considerations, and current practices are examined. Particular attention is given to unbolted linings, with and without secondary linings. Probable future developments are considered.

Jan 1, 1989

By Kenneth N. Han, Yichang Guan

The dissolution behavior of metals from Au/Ag/Cu-alloys has been studied using rotating disc electrodes in solutions containing acids, cyanide, and ammonia. Electrochemical methods as well as leaching tests were adopted in this study. The results showed that there was no galvanic effect on the dissolution of metals from homogeneous alloys. In aerated cyanide solutions, the dissolution of gold, silver, and copper from their alloys was partly controlled by surface chemical reaction, but largely by mass transfer. On the other hand, the galvanic coupling effect played a very important role in heterogeneous alloy systems.

Jan 1, 1995

By Donald W. Peters

The 191 million acres of public lands that are managed as National Forest System Lands contain extensive geologic habitat for over 40 industrial minerals. The Forest Service actively encourages exploration for and development of industrial mineral deposits within the National Forests. However, due to competing interests, the Forest Service may not always be able to accommodate industry needs. In order to successfully compete with ever-increasing demands for all resources in the 1990's, industry needs to become more active in public involvement and education and in communicating its contributions and needs to public land managers.

Jan 1, 1991