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By S. K. Kawatra, R. A. Seitz

Nonpolar hydrocarbon oils are commonly used in the flotation of minerals to fulfill a number of roles. These roles include reducing overall reagent costs by replacing part of the collector addition, improving coarse particle recovery without reducing selectivity, as well as several others. This paper will cover the types of oils which are available, their physical and chemical characteristics, and the effect of these characteristics on the function of hydrocarbon oils in flotation. In addition, techniques for improving the behavior of oils will be discussed.

Jan 1, 1986

By James E. McTurk, Sheldon B. Bland, Roger E. Melley

During the first fifteen years of operation at the Syncrude facility in northern Alberta, numerous improvements have been made in the field of ore conveying. The unique nature of the material conveyed coupled with the wide range of environmental conditions encountered results in a number of unparalleled challenges. Most of the improvements have been brought about with the use of detailed field evaluation. This paper outlines some of the programs which have been run to optimise belt and system construction, and conveyor performance and utilization.

Jan 1, 1993

By A. J. Surtees, M. P. Evans

This paper discusses the development and application of sophisticated monitoring equipment used to measure the operating parameters of conveyor systems. With the radical reduction in price of computer hard- ware and software during the last decade and an associated increase in memory capacity, the concept of continuous conveyor monitor is now a reality. With this tool, the various problems normally encountered in large conveyor installations can now be avoided at an early stage. • The four main areas of application are: • Design verification • Hand-over certification • Preventative maintenance and increase of system availability Failure analysis The paper introduces the techniques used and gives examples where the service has been used.

Jan 1, 1996

By C. L. Schneider, R. P. King

Size distributions and liberation spectra were measured in samples taken from 10 streams in a taconite milling circuit under normal operating conditions. The size distributions were deter- mined by sieving and the liberation spectra by image analysis using the linear-intercept method with proper stereological correction. The measured data were used to validate a simulation of the milling circuit using MODSIM which included the calculation of both size distributions and liberation spectra. Both the measured data and the simulator showed that liberated magnetite was returned to the mill in the cyclone underflow. The simulation will be used to improve the economic performance of the plant.

Jan 1, 1995

By V. K. Karra

Research by various workers has shown compressive comminution to be significantly more efficient than impact comminution. Based on the work being done at Nordberg, wet compressive crushing in cone crushers producing finer and finer products, shows the feasibility for partial substitution of conventional tumbling mills. For further substitution, major challenges are processing of fine feed slurries in cone crushers to realize a significant size reduction of the particles, and understanding the limitation of the gyratory type units in terms of finest product achievable. The paper addresses the challenges involved, efforts at Nordberg, and the implications to conventional comminution flowsheets.

Jan 1, 1989

By S. Zaman, John Bulter, M. E. Defoe, Franklin T. Davis

This section deals with the carbon minerals and materials: graphite, tar sands, gilsonite, and diamond. as well as sulfur and the sulfides of mercury, arsenic, antimony, and bismuth. Table I contains the production figures for each of these commodities in the United States and in the world. Specifications for concentrates are also summarized as are prices for concentrates at the time the section was written. In each chapter an attempt has teen made to describe the more common commercial mineral involved with the commodity, the processes used to recover and concentrate the minerals, as well as geographical areas where these processes are utilized.

Jan 1, 1985

Changes have been made in the Bulletin, Section I., for this month ; Personal and Employment columns have been added, and a Forum, in which will be included letters and discussions of general interest to members of the Institute ; live news and new matter have been inserted near the front; lists of officers and committees are placed next to the technical section, while standing matter and other information which is interesting chiefly when sought for, has been segregated as much as possible. Members are urged to co-operate with the Editor by sending in news items of themselves and others, and by giving some of their spare time to this department each month.

Jan 4, 1913

By Ronald D. Hill

Acid mine drainage is the result of the oxidation of pyrite and similar iron sulfide material and the release of iron and sulfuric acid into the environment. In addition to the acid water flowing from underground and surface mines, spoil materials in surface mines are acidic and will not support good vegetative growth; thus erosion is a major problem. Lime and limestone are the major neutralizing agents used to treat these acidic conditions. Lime is the reagent preferred by industry for treating acid discharges, although a few companies use limestone. Agricultural lime- stone is used to "sweeten" acid spoils.

Jan 1, 1974

By Jon C. Yingling

Techniques for optimization of mineral processing flowsheets are reviewed. Though not yet widely used in the minerals industry, approaches for chemical process optimization based on successive quadratic programming (SQP) algorithms may be employed to determine optimum unit design and control settings for a mineral processing flowsheet. Moreover, in certain mineral processing flowsheet applications, specialized techniques can be applied because of the nature of the system relations. These techniques offer advanta es in efficiency. Moreover, their capability exceeds that o f the SQP approaches since simultaneous optimization of circuit configuration and unit controls can be addressed.

Jan 1, 1990

By Fathi Habashi

Precipitation of a metal from an aqueous solution of its salts by another metal is known as cementation, because the precipitated metal is usually cemented on the added metal. This phenomena was once described by the alchemists as "transmutation," when they dipped a piece of iron in a solution of copper sulfate and the iron was coated with a layer of metallic copper. The process can be predicted in terms of electrode potentials. The metal with the more positive (oxidation) potential, as given in Table 13-1 of the electromotive series, will pass into solution and displace a metal with a less positive potential.

Jan 1, 1970

By D. R. Spears, C. E. Jordan

The U.S. Bureau of Mines examined the influence of turbulence on the fine bubble flotation of fine-sized (minus 40 micron) galena in order to improve flotation efficiency. Fine bubble flotation was carried out in a spinning-disk flotation cell and was compared to results obtained from flotation in a conventional cell at equivalent agitation levels. An automated electrochemical technique was used to monitor the turbulent velocity distributions of the fluid within the cell as a function of time and position. The velocity profiles were used to increase the precision of the fine particle, turbulent flotation model. While improved flotation response was obtained with intense agitation, the effect of bubble size was small. These results matched the model's predicted response for fine particle flotation.

Jan 1, 1989

By W. E. L. Minter

Discussion by E.S. Cheney Minter (1990) has provided an excellent summary of the sedimentology and theories of origin of the Witwatersrand paleoplacer Au/U deposits. However, recent stratigraphic, metamorphic and structural -tectonic research is radically changing the concepts about the Witwatersrand that now occur in most textbooks, review articles and North American minds. Presently, these concepts are biased by the past sedimentological research so well described by Minter. Specifically, the Witwatersrand Supergroup is Archean, does not occupy a depositional basin and is significantly metamorphosed and deformed. Thus, many of its sedimentary features, including the mineralogy of its ores, have been modified. The importance of the Witwatersrand ores cannot be overestimated. Since their discovery in 1886, they have produced 52% of the gold mined in all of human history (Pretorius, 1989). Setting Only one depositional item needs to be added to the excellent

Jan 1, 1992

By Y. J. Wang

The use of controlled recirculation began in the early 1930s. Although this method has been applied in many mines since then, a generalized comprehensive network analysis is still lacking. This paper presents a unique approach in which the ventilation network with a controlled district recirculation is divided into two subsystems: a main subsystem and a recirculation subsystem. The subsystems are analyzed individually, and the results and their relationships are then integrated into discussions of the total ventilation system. The analysis of the recirculation subsystem is facilitated by introducing a nondimensional parameter (A), which represents the ratio of the air quantity for the working face to that for the subsystem. As a result, far and regulator pressures and air power for various recirculation arrangements can be effectively expressed as a function of and the subsystem air quantity. Numerical examples are included.

Jan 1, 1997

By G. P. Brahmaprakash, K. A. Natarajan, N. Jyothi, K. N. Sudha

Some important electrochemical aspects involved in the bioleaching of mixed sulfides have been discussed with reference to selective sphalerite dissolution from different binary mineral combinations. Combination potentials and galvanic currents were measured in different binary combinations of sphalerite with other minerals such as galena, chalcopyrite and pyrite in order to under- stand the electrochemical dissolution behaviour of sphalerite when coupled with other minerals. The effect of applied DC potential was also studied with reference to selective sphalerite dissolution from a binary mineral mixture. An application of a potential of -500 mV (vs SCE) was found to enhance bacterial growth as well as selective sphalerite dissolution. Factors influencing bioleaching of sphalerite under a negative applied potential are discussed.

Jan 1, 1989

By R. Harris, M. Misra

Column flotation technology has a demonstrated potential for recovering clean coal from high-ash waste fines. The effect of different variables such as air flow rate, frother addition, depressant addition, percent solids and particle size on the quality of separation are discussed. Results indicate that air flow rate and depressant addition are the important variables which control the selectivity in the flotation of fine coal in a column cell. Separation efficiency achieved with column cells is significantly better than that with conventional flotation cells. Under appropriate experimental conditions with a deep column, more than 80 percent coal can be recovered in the concentrate containing 10 percent ash from waste fines containing over 60 percent ash.

Jan 1, 1988

By R. J. Sweigard, R. V. Ramani

Estimated costs and revenues can be used in evaluating postmining land use alternatives. However, postmining land use decisions have to be made in an environment complicated by several additional factors. These factors, including cultural, natural, and managerial issues, are not as easily quantified as costs and revenues but may be more important determinants. There fore, some approach is needed to attach relative weight to the various factors. The concept of fuzzy sets assembled into a structured hierarchy facilitates analysis of the relative value of individual factors and their impact on each alternative under consideration. In this paper, a method is presented that employs fuzzy set analysis to evaluate postmining land use plans on the basis of these nonquantitative factors.

Jan 1, 1988

By G. T. Adel

The growing interest in column flotation has created a need for a fundamental scale-up procedure which is capable of meeting the necessary design and control criteria for industrial columns. Unfortunately, most of the avail able scale-up procedures deal with column diameter only and not overall column volume. Current work focuses on the effect of bubble size distribution and air hold-up on the scale- up of column volume. A series of pressure transducers has been used to measure air hold-up along the length of a bench-scale column. These measurements have been used to validate a mathematical model of the air phase. In addition to scale-up, the model appears to have the potential for use in control of air hold-up and bubble size.

Jan 1, 1990

By Robert J. Wise, Mark Alspaugh

Underground longwall coal mines depend on conveyor haulage to transport large volumes of coal from the longwall face conveyor to the mine portal. In the last few years, the need for longer and larger longwall panel conveyors has become very significant. In order to keep conveyor equipment to a minimum and still transport higher tonnages over longer lengths, intermediate drive technology has been developed. The use of DC motors and controls in conjunction with load sharing techniques have a1 so proven effective. A case study of a new longwall panel conveyor at Utah Fuel's Skyline Mine incorporating these design techniques will be presented.

Jan 1, 1993

By Thomas E. McNider

On July 20, 1990, a Spontaneous Combustion Control Plan was approved by MSHA for Jim Walter Resources, Inc. No. 5 Mine. The mine operated under the plan for twenty-nine shifts before MSHA revoked the plan. A total of fifty-five seals were constructed during the process of implementing the plan. The major difficulty in applying the control concept resulted from problems controlling leakage at the numerous seals. The number of seals was a direct consequence of attempting to merge the traditional bleeder system, used in all the Blue Creek Mines, with the bleederless system Jim Walter Resources proposed as a means of controlling the spontaneous combustion hazard. This paper discusses Jim Walter Resources experience with spontaneous combustion control and the new safety standard which applies to underground coal mines that demonstrate a history of spontaneous combustion and how this standard would apply to our No. 5 Mine. The new Ventilation Standards were published in the Federal Register on May 15, 1992, and scheduled to go into effect August 16, 1992.

Jan 1, 1993

By James P. Cooney

The global mining industry is in the process of redefining its activity and purpose in terms of sustainable development. This process is impelling a growing number of companies to engage their stakeholders on environmental and social issues. Nongovernmental organizations (NGOs) have customarily acted as critics of the mining industry's performance. A new relationship between mining companies and NGOs is emerging in the context of sustainable development, ranging from dialogue to joint action. If positive interaction among mining companies and NGOs is to succeed, clear terms of engagement must be articulated, and measurable progress toward achieving both corporate and NW objectives must be demonstrated. The experience of Placer Dome is illustrative of the rewards and challenges of engaging with NGOs.

Jan 1, 2001