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By Lewis Gordon, Alan Morrow, Aundra Nix

At the ASARCO Mission Mill, a multivariable, predictive controller was used to optimize parallel grinding circuits, improving throughput and product size. Using a dynamic model of the grinding circuit developed from on-line testing the software manipulates 4 variables to control 14 quality and constraint variables in each circuit. Traditionally, model-based control in grinding is difficult due to ore changes. This is addressed via a novel method to predict mill overload and automatic model switching.

Jan 1, 2000

By R. P. King, S. Middlemiss

A method is developed to convert a measured distribution of fracture energies to the equivalent work index. The method assumes that the energy required to grind the material from the feed size distribution to the product size distribution is equivalent to the sum of the impact energies that are required to reduce the feed material by successive single impacts to the required product size. The method was tested by measuring the fracture energy distributions for quartz and comparing the resulting calculated value of the work index with the work index for this material measured using the conventional Bond laboratory procedure.

Jan 1, 1998

By Maurice Rey

The copper segregation process is designed to concentrate oxidized copper ores or mixed sulfide-oxide copper ores which are refractory to normal and cheaper mineral dressing or leaching processes. Such ores contain copper silicates or highly disseminated copper minerals in a gangue not entirely free from limestone or dolomite. Concentra¬tion by flotation is, under these circumstances, not possible and the acid-consuming constituents do not permit acid leaching. A high temperature treatment at 700-800°C, in the presence of a small amount of sodium chloride and of finely divided carbon, concentrates the copper into easily floated metal by a kind of reducing chloridizing roast. The sulfides, if present, are either oxidized in the heating stage and react like oxides or float with the metallic copper in the flotation step. The ores which have the aforementioned characteristics and which are high grade enough to pay for the treatment are scarce, so that the process has only a limited application. Theory of Copper Segregation Sodium chloride, reacting with water vapor and the acid gangue constituents, produces hydrogen chloride which reacts with the copper minerals. The copper is volatilized as cuprous chloride and immedi¬ately reduced on the coal particles by hydrogen emanating from the volatile matter of the coal and from the water-gas reaction. Hydrogen chloride is

Jan 1, 1985

By Ian J. Duckworth, Pierre F. X. Mousset-Jones

A detailed heat flow project was conducted at the Homestake Mine in Lead, South Dakota. This paper presents results obtained from a stope sensor system installed in the mine. The design and installation of the system are described in detail in a previous paper (Duckworth et al., 1992). The major project objective was the construction of a comprehensive heat flow data base to allow the design and testing of a new climate prediction model applicable to irregularly shaped underground excavations in non-homogeneous surrounding rock types. A mechanized cut-and-fill (MCF) stope contributes a substantial overall heat source in a mine, and the effect of this source on the working environment must be considered when planning future ventilation and refrigeration requirements. The relative magnitudes of the component heat sources encountered with the MCF mining technique are presented, having been computed from actual stope beat flow data collected over a one-month study period. The percentage of the overall heat load that is removed from the scope for each component heat sink is evaluated, and the overall energy balance is analyzed. A one-month study length was considered a sufficient period of time to allow stope monitoring for a complete range of mining conditions.

Jan 1, 1993

By Kenneth J. Reid, Marian S. Stachowicz

A preliminary evaluation of a new in-stream particle size analyzer has been carried out using materials obtained from a taconite plant in Northern Minnesota. Results are reported for bench scale, pilot scale and full scale tests, the latter being carried out in a taconite plant concentrator. The unit employs a novel scanning laser microscopy principle and details of the equipment configuration and operating principles are presented and discussed. Data acquisition is via an eight channel digital electronic system and particle counts are collected on the basis of reflected light pulse time intervals which are a direct measure of particle size. Output is available as an eight point individual or cumulative size distribution or as computed averages. The practical aspects of sample point location and flow requirements for reproducible results are outlined and discussed.

Jan 1, 1990

By John A. Herbst, William T. Pate

Column flotation is emerging as one of the most important new separation technologies of the decade. Attendant to this development is the need for a quantitative understanding of the dynamic characteristics of columns. An understanding of the many important sub-processes occurring in the cell makes possible the development of dynamic simulators for flotation columns which will aid in the design of control systems for dynamic and steady state optimization. This paper presents a dynamic model for the column flotation cell developed from a population balance point of view similar to that which has been successfully applied to conventional flotation cells. In particular, the mixing that occurs within the pulp is modeled with a distributed-volume, mixer-in-series model as an approximation to the axially dispersed plug flow transport that occurs in the cell. This simpler approach avoids the distributed transport model which often leads to mathematical intractability. Other phenomena dealt with are the attachment and detachment of particles from bubbles in the froth and pulp, the transport of water and the bubble volumes with the froth and pulp phases. Simulation of the flotation of an Illinois No. 6 coal in a pilot plant flotation column were performed to test control strategies.

Jan 1, 1989

By Haydn H. Murray

The three major catalyst markets that utilize industrial minerals as raw materials are petroleum refining, chemical processing, and emission control. Because of economic, competitive, and regulatory pressures, catalyst producers are pushed to develop products with improved performance to meet changing environmental standards. Also, refiners are demanding new families of cracking catalysts that will crack residual fuels. In 1987, worldwide cracking catalyst sales amounted to $457 million (Occelli, 1988a). Recently enacted federal and state laws to improve air quality have prompted strong growth for environmental catalysts, which in 1989 accounted for more than a third of the $1.9 billion catalyst market in the United States (Farrauto, Heck, and Speronello, 1992). A catalyst is a material that promotes or enhances a chemical reaction but does not itself enter into the reaction. One of the more important mineral groups used as catalysts is clays. The first recorded use of clay as a catalyst was its use in the dehydration of alcohol (Bondt et al., 1797). Clay minerals that are used as catalysts are kaolinite, halloysite, smectite, palygorskite, and sepiolite. Minerals used as catalysts, catalyst supports, or as a raw material to make zeolites are kaolinite, halloysite, sodium montmorillonite, calcium montmorillonite, hectorite, palygorskite, sepiolite, talc, calcined kaolinite, gibbsite, chlorite, and titanium dioxide.

Jan 1, 1994

By S. Corrent, F. A. V. Guimarães, M. G. Barbosa

"INTRODUCTION Moisture can be a villain, so new technologies have been explored to make more viable the production of high moisture iron ores. The current work presents the attempt of the utilization of a superabsorbent polymer (SAP) to aid in the screening process and in the ore handling process, such as stockpiles reclaiming and vessels/trains discharge in sub-zero temperature conditions. The results have shown that the polymer can be used in certain cases to improve productivity and increase safety in the process of handling the material (by increasing the TML). However, for size separation no advantages were found upon the use of the polymers. WATER ADSORPTION MECHANISMS The use of water in mineral processing is constant as its utilization brings an increase in the efficiency of separation. Although we have better results in the processing with water, materials with a high content of “natural” moisture can be very difficult to be treated by the conventional methods of separation. Nowadays many studies have been conducted in order to understand the effect of adsorption of water in the particles of complex minerals. Those studies have being divided in many different lines of research such as contact angle of a drop of water and the surface of the mineral to determine hydrophobicity, the particle size distribution and the porosity of particles. Mainly two forms of adsorption of water by the particles are possible: one the water is retained inside porosity of the particles. Laboratory tests developed in China have showed that capillary adsorption is faster in coarser particles that achieve the saturation degree earlier than finer particles (Xuewei Lv et al., 2011). The so called non-porous model considers the effect of water in the bulk sample of iron ores, in a physical connection when all the water works as a binder between particles as shown in the figure 1.If we take into account the compressibility of the system and compaction due to the weight of the bed over the particles, the thickness of the water film between particles is the same but the volume inside different particle size systems is much higher than in a system with particles of same size."

Jan 1, 2018

By J. B. Pateiro Fernandez, S. Möllerherm, E. Drüppel

"Since 1997 the Institute of Mining Engineering 1 at the Aachen University is dealing with the concept of sustainable development in the mineral industries. During this time it has conducted several research projects in this field. Its latest project is on the development of sustainability indicators for the German mineral industry. This paper describes some results of this project. A process chain analyses have been carried out identifying economic, social and environmental effects of the minerals extraction. Thirty indicators reflecting the particular conditions in the mineral industry have been designed. One important challenge was the design of quantifiable indicators taking into account the life cycle of a mining operation as well as mineral beneficiation and enrichment of the raw material."

Jan 1, 2005

By T. Tamagawa, I. Iwasaki, N. X. Fu, M. Kobayashi

A three-stage fluidizing-bed process consisting of chlorination, selective oxidation and sulfur chloride conversion was tested for processing chalcopyrite concentrate. It was found that the use of excess oxygen was essential for the stable operation of the oxidation reactor. The excess-oxygen gas inevitably causes the oxidation of the sulfide concentrate in the chlorination and sulfur chloride conversion reactors. A new flowsheet is proposed to separate the chlorination and selective oxidation steps with separate flow paths of the fluidizing gases, thereby, preventing the passage of excess-oxygen gas in the chlorination and sulfur chloride conversion reactors. The feasibility of the proposed flowsheet was demonstrated in a laboratoryscale fiuidizing bed setup.

Jan 1, 2002

By Gemei Yang, Yihui Zhao

In caved goaf, the friction loss of fluid head is: [h = (R'+ R/Q/ )] Q (for one-dimensional transition flow). The R' and R, which are the functions of two dimensional spaces, are calculated through an empirical formula. Then, the bulking factor and permeability are determined. It is supposed that the airflow in porous media are similar to those in tiny tubes crossing each other. Therefore, the network calculation technique can be used to tackle the field transition flow problem. A lot of case studies showed that the emission of methane in mines mainly depends on the air velocity and has little relation to air pressure. Summing up our experience and experiments, we provide an empirical formula to calculate the gas emission rate per unit area. By means of mass conservation and network calculation, the methane content distribution in steady-state is worked out. Then the dynamic change in airflows and gas content can be analyzed by the characteristic-difference method.

Jan 1, 1987

By Andrzej M. Wala

A prototype expert system for planning and designing an underground coal mine has been developed in a doctoral study at the University of Kentucky. This prototype expert system for underground coal mine planning and designing consists of a number of knowledge bases concerning different elements of design (e.g., ground control, excavation and bulk materials handling, ventilation, etc.). The objective of this paper is to present the development process of the ventilation design knowledge base for this prototype. This expert system prototype is intended for building an instructional expert system for underground coal mine design. Therefore, the undergraduate course on mine design has been used as the basis, for its development. Because of the availability of knowledge and expertise, this research study has been limited to development of a knowledge model for the Appalachian coal mining region.

Jan 1, 1993

By William L. Carter

Through your presence here this morning and your membership in the Society of Mining Engineers, you have shown that you are interested in keeping abreast of the latest technology and mining procedures, want to be part of the continuing progress made by those in your profession, and are looking for ways to participate in expanding your professional and personal experiences and skills. All of these factors are part of your continuing education, the need for peer identification or recognition, and the desire to make a specific contribution to strengthening your profession. However, you may be here with or without your company support and financial backing, unless you are self-employed. Whether you are here for the above reasons, or for many others, your presence reflects a recognition of the importance of participating in the organizational structure of your profession.

Jan 1, 1981

By I. WILKOMIRSKY, J. BECKER, F. Parada

CORRECTION

Jan 18, 2023

By W. R. Bush

Radiation protection in uranium mines and nuclear reactors is compared, with the objective of determining if any radiation protection practices which have worked well in one area can be adapted to the other area, especially from reactors to mines since radiation protection is more highly developed in reactors. Several areas are identified where improvements can be made in radiation protection in mines, the most important being improvement in ventilation at the workplace, greater attention to special monitoring during upset conditions, and a need for a substantial increase in radiation protection staff. It is concluded that, although considerable room exists for improvement, the general approach to radiation protection presently being followed seems appropriate for the circumstances encountered in mining.

Jan 1, 1981

By L. Zhou, D. Bahrami

Mine ventilation is one of the most important aspects of mining operations in underground mines. It is critical to maintain and deliver required fresh air to the active areas to reduce the risk of overexposure to hazardous contaminants or explosive atmospheres. An unexpected or unknown event such as roof collapse, unexpected mine door closure/opening, a fire/explosion, or fan malfunction could adversely alter the airflow distribution within the mine ventilation network that could lead to a hazardous underground environment. Knowing the occurrence and location of such an incident is of critical importance. In this study, the authors developed a novel methodology to assist mine operators in quickly identifying the location of any abnormal airflow change within the network using the airflow changes at monitored airways. The concept is based on a direct derivative method developed by the authors. This paper provides the details of the developed method as well as numerical verification examples. The application of this method can benefit mine operators and safety personnel in making better decisions during a mine emergency response operation to mitigate hazardous conditions arising from an unexpected airflow disturbance

Mar 2, 2022

By Mike L. Aziz, Keith D. Ferguson, Glenda Ferris

The Equity Silver mine has been a severe producer of Acid Rock Drainage (ARD) since 1982. The mine was closed in 1994 and a compacted clay cover installed, but ARD continues to be produced. Three permanent employees manage the collection and treatment system at the site. The site still poses a significant environmental risk to the environment and downstream users and requires a high level of diligence. Various stakeholders' perspectives of the risk posed by Equity, and what constitutes acceptable risk, will be examined in this paper from a company operation staff, corporate environmental manager and downstream environmentalist perspective.

Jan 1, 2000

By C. R. Stephan

Explosion-resistant seals in underground coal mines isolate the environment within the sealed area from the active workings of the mine. The current United States Title 30 Code of Federal Regulations (CFR) requires these seals to be constructed of solid concrete blocks. The CFR also allows for alternative methods or materials to be used to create a seal if they can withstand a static horizontal pressure of 138 kpa (20 psi), provided the method of installation and the material used is approved in the ventilation plan. The purpose of this report is to identify those explosion-resistant seals that have been tested and meet or exceed all the requirements of the CFR.

Jan 1, 1997

By Howard E. Banta

From Alaska to Florida and California to Maine, the National Forest System (NFS) is host to unprecedented levels of prospecting and development. The NFS is large (191 million acres), geologically attractive from the mineral standpoint and relatively unexplored. Significant recent finds and developments involve silver, gold, platinum group metals, molybdenum, cobalt and phosphates. Exploration and development are closely regulated, but most of the NFS is open. The Forest Service endeavors to be a good host to the mineral industry, but increasingly is asked or forced to delay or disapprove mineral projects to protect the environment.

Jan 1, 1984

By G. Robert Ganis

The folded Appalachians are a physiographic province of eastern North America extending from Nova Scotia to Alabama. The province strikes through the state of Pennsylvania (see Fig. 1) comprising roughly 20 percent of the state and it is here that the focus of this paper will attend. The province is a thick sedimentary sequence which was compressed into a folded mountain belt by the Appalachian Orogeny which terminated at the end of the Permian. The stratigraphy contains both carbonate and non-carbonate rocks as a reflection of the depositional environment at any specific time and place during the Paleozoic geosynclinal accumulation. Although a great deal of variety and difference exists in the geology from one end to another, a common thread of structural and stratigraphic style exists. Carbonate rocks, limestones and dolomites, comprise a substantial percentage of the total Appalachian stratigraphy and are interbedded with clastic materials such as sandstones, siltstones, and shales. The carbonate rocks are extensively mined and collectively represent a vast economic resource.

Jan 1, 1983