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By J. C. Watts

Ball mill grinding circuit control has received increasing emphasis in the past few years due to such factors as declining ore grades, increasing production costs, and advances in analytical devices and minicomputer technology. Since ball mill circuits have been a traditional bottleneck in mineral processing plant throughput, control systems often improve through- put without requiring additional processing equipment. In addition, much of the variability of the grinding product size and consistency is often removed, allowing better process operation downstream. Among the problems which arise in designing and implementing a process control strategy for ball mill circuits are circuit constraints imposed by processing equipment and local management, proper instrument selection, installation and maintenance, and use of calculated or inferred variables for process measurements. This paper discusses these problems and attempts to identify valid approaches to their solution.

Jan 1, 1979

By Julius Rubinstein, Victor Badenicov

The development of column flotation is the most significant achievement in the area of mineral processing in the last few decades. The high efficiency of column flotation allows a reduction in process time, a decrease in the number of cleaner stages and in the volume of the circulating load in the flotation circuit, and, as a result of this, an increase in consistency and reliability of operations. Unique multisectional column flotation apparatuses were developed. Such designs have a number of essential advantages as compared to monocells. A change from monocells to multisectional column allows to provide favourable conditions for separation of particles of various floatability. To attain that aim particular hydrodynamics and aeration regime is established in each section of the column, operational variables being adjusted according to the floatability of the material. Therefore in multisectional column machines the material-apparatus feedback can be established, process variables optimized depending on the characteristics of the floated materials. This concept forms the basis of column designs we have developed. For the first time column cell with alternating slurry Rows (combination of co- and counter-current flows) were developed and commercialized . Successful operation was reported of the new generation of columns with cell volumes of 10 to 80 m3 and the height of 4-6 m in copper, molybdenum, antimony, tungsten and nickel ores and coal slurry processing at different plants. Operation experience of these cells showed their considerable design and operational advantages and verified the proposed options and relationships. The new apparatus is provided with a pneumohydraulic aerator allowing to control bubble size distribution, the service life of the aerator is not less than two years. A multilevel flotation model was developed and used to work out a technique of column design and process parameters calculation. A method of the apparatus design parameters calculation based on laboratory test results (scaling up) was worked out. The method is based on flotation macro and micro-hydrodynamics simulation.

Jan 1, 1995

By U. K. Custred

In 1973, the United States production of marketable phosphate rock set a record in excess of 42 million tons. This production rate is expected to continue to increase, due to the growing international requirement for fertilizer, at a rate exceeding 5% per year well into 1977. This trend contrasts sharply with the reduced phosphate rock production levels of the 1966 - 1971 period. The natural consequence of this growing phosphate rock market is an evaluation of the variety of means whereby plant capacity can be most effectively increased. One approach toward increased plant production capacity is through large capacity flotation cells provided they can be successfully applied to the recovery of the relatively coarse product which is characteristic of the phosphate rock feed. This paper will summarize the results of a nine month evaluation test program, conducted at the Haynesworth Mine at Bradley, Florida in which the flotation circuit "specific capacity" (tons feed/ft.2 floor space) and "specific input power" (Hp/ton feed) were determined, and the feasibility of achieving economically acceptable concentrate grade and recovery levels was demonstrated, using large, high capacity, flotation cells.

Jan 1, 1974

By Charles U. Keranen

The Tilden Mine is an iron ore mining, processing and pelletizing facility located on the Marquette Iron Range in Michigan's Upper Peninsula. It has a designed capacity to produce 8 million long tons of pellets annually from 21 million long tons of crude. It is a partnership owned by The Cleveland-Cliffs Iron Company, Algoma Steel Corporation, LTV Steel Corporation, the Steel Company of Canada, Wheeling Pitts- burgh Steel Corporation and the Sharon Steel Corporation. Cleveland- Cliffs manages and operates the Tilden. The crude ore averages 35% iron and is primarily non-magnetic iron oxide and silica. The major ore mineral is martite. Hematite, earthy hematite, goethite and magnetite are also present. The principal gangue mineral is chert. The ore grains are mostly in the 10 to 25 micron size range which necessitates very fine grinding for liberation. The concentrating process is the most complex one used in the iron ore industry. The unique technology for Tilden was developed in the mid and late 60's. The design and construction occurred in the early 70's and operation of the first phase which was of 4 MLTPY capacity began in October. 1974. Expansion of the facility to the current 8 MLTPY capacity was completed in 1979. Chemicals are the key to the beneficiation process at the Tilden Mine. The flowsheet utilizes selective flocculation - desliming, cationic silica flotation and concentrate dewatering by thickening and filtering. Nine different process chemcals are used. The control of the reagent feed systems is highly auto- mated. The entire concentrator is operated from a central control room. The concentrator flow diagram is presented in figure 1. The plant consists of 12 primary autogenous grinding lines, a common crushing circuit to handle an intermediate product within the primary grinding section, 24 pebble mill lines with cyclones and deslime thickeners, 12 flotation lines, 4 concentrate thickeners and slurry tanks, 8 lines of filters with six machines per line, and 2 tailings thickeners. A pumping system was installed in 1980 to permit the direct return of tailings thickener overflow water back to the reuse water pumphouse.

Jan 1, 1986

By D. W. Fuerstenau, J. Vazquez-Favela

This paper shows how the efficiencies of size-reduction processes depend on the mode of particle constraint and energy transfer within the comminution device: namely, whether the process consists of single-particle loading, confined-particle-bed comminution or loose- (unconstrained-) particle grinding. The relative efficiency of single-particle comminution, ball-mill grinding and particle-bed comminution in the recently invented high-pressure roll mill is evaluated by making use of the self-preserving nature of the size distributions of comminuted products. The highest energy efficiency can be achieved by utilizing a hybrid two-stage system in which the material is first ground in the high-pressure roll mill and then the ball mill.

Jan 1, 1998

By A. E. Hall, D. M. Mchaina

This paper outlines a proposed research project to investigate secondary sulphide ignitions. Sulphide dust explosions have resulted in loss of production and considerable capital and equipment replacement cost in Canadian mines. The practical application of laboratory test results to actual mine situations presents a complex problem and is a field requiring immediate investigation. The factors contributing to the outbreak of sulphide ignitions are not clearly understood. This indicates a need for future research to study the influence of blasting parameters, exhaust temperatures, and dust characteristics on secondary ignitions at source. The aim is to establish realistic quantities for each of the parameters and develop a model that will incorporate field and laboratory quantities. It may be possible to predict outcomes of sulphide ignitions when the parameters are known. It is also planned to study the techno-economic feasibility of the preventive and control methods. One aspect of planned future research requires quantification of some terms by obtaining measurements of pollutant concentrations and size distribution of the airborne dust in an underground environment immediately after a main blast. A blast-proof aerosol sampling package to measure the source term will be designed. This sampling package will consist of a sampling section and a shield which will be capable of withstanding a blast explosion. The accuracy in measuring the variables and combination of variables will be the main focus in this proposed study.

Jan 1, 1987

By Osvaldo A. Bascur, J. P. Kennedy

Companies have installed powerful desktops for their personnel and instrumentation and control systems in their plants. These desktops are, in many cases, connected to a company intranet. Still, process engineers have to obtain their data manually. Engineers use process calculations from manually calculated averages from the plant; field operators collect equipment data on log sheets; and maintenance engineers collect critical information on log sheets. All of this information resides in individual machines. What are the strategic tools that will enable collaboration between them? How can operators, engineers, and managers access plant information to proactively increase their effectiveness in process troubleshooting, plant debottleneclung, aligning with business strategic and customer demand, satisfying environmental and safety regulations, developing capital projects, and implementing control strategies? A nonintrusive environment at the desktop is required to provide the process information to these workers. How can value be added to MS Windows technologies with the legacy systems at a minimum cost? There is no straight answer; however, there is a proven framework to leverage the large investments in new technologies. Objects and components are changing the way everyone relates to their computer and networks. Three examples will be described to demonstrate paradigm change. Today, process engineers can access data at the required level of detail for analysis of critical process variables at their desk or remotely. 1. Process Troubleshooting and Analysis: The engineer can develop an inferential calculation, trigger a process advisor to deter- mine the behavior of the units for the last day, and get the population of a set of batches (heats, blocks, rolls, sheets, etc). 2. Process Control and Optimization: The engineer can connect to a process simulator at steady state or a dynamic simulator of the process to evaluate new control strategies or process unit line-ups and use the process simulator as a process observer for fault diagnosis. 3. Collaboration with Accounting and Maintenance: The engineer can review reconciled data and the process mass balances, suggest maintenance cleaning or recalibration of flowmeters, and evaluate key control performance of all advanced controls.

Jan 1, 1999

By Gary W. Hausler

Bergbau AG Niederrhein, a subsidiary of Ruhrkohle AG; Essen, Germany, is working coal mines on both sides of the Rhine River. The Prosper Mine in the City of Bottrop has a production of about 13,000 tons per day and has been in operation since the turn of the century. Mining has moved to the north as coal deposits south of Bottrop are exhausted. To facilitate ventilation, material handling, and transportation new shafts are being constructed in the northern coal fields. The Prosper 10 shaft is being sunk to develop the Prosper - Haniel coal field which has reserves of 280 million tons. In October, 1976 Bergbau AG Niederrhein awarded the shaft sinking contract for the 1047 m deep, 8 m inside diameter Prosper 10 shaft to Gewerkschaft Walter; Essen, Germany. Construction costs will amount to about 40 million DM with construction completion scheduled for 1981. GEOLOGY The shaft, located near the town of Kirchhellen north Bottrop, is being sunk in the Grafenwalder Horst between two faults on the south west flank of the Kirchheller Anticline. 270 m of upper cretaceus sands and marls overlay sandstone bedrock at the shaft location. The upper 124 m of this section contain highly saturated sands interspersed with marl. In order to successfully sink the shaft through this section, ground stabilization by freezing was used.

Jan 1, 1979

Integrated mining information and process control systems can reduce information delays, enhance decision making and improve the responsiveness of mining operations to, for example, variations in market conditions, mineral grades and ground conditions. This paper examines developments in the areas of: monitoring, data analysis and diagnosis,' communications systems; integrated mining support system;, and process and machine control. It concludes that the development of a comprehensive information technology plan is fundamental to the phased implementation of these technologies. In addition, hardware and software standards and concurrent digital design and simulation practices in selected manufacturing industries are examined and concluded to have relevance to the mining industry. Integrated information and process control systems will lead to emergence of the "digital mine". Such advances in mining information infrastructure as well as mining equipment will enable mining operations to shift from mass production methods to leaner production techniques. "Lean mining" aims to enhance and accelerate cash flow over the life of a mine by focusing on reduction of' throughput times; stockpiles for volume and quality control; and wastage and rework.

Jan 1, 1995

"A commercially available through-the-earth (TTE) communications system was evaluated at an underground coal mine in eastern Kentucky. This field study was conducted as part of a larger multisite evaluation of available TTE systems. The mine detailed in this paper was idled at the time of the study, which provided the nearest practical representation of a postevent mine shutdown environment. For this study, surface-to-underground and undergroundto- surface communications were tested. Standard deployments of the TTE system using the manufacturer’s recommended procedures were able to achieve clear communications between underground and surface locations. Other arrangements of the units yielded mixed results. Future experimentation is planned to further examine the phenomena observed at this mine IntroductionThe ability to establish effective communication between surface and underground personnel after a mine event is essential for both evacuation and rescue efforts. Current wireless underground communication technologies are reliant on intermediary physical infrastructure, such as antennas and repeaters, to enable underground communications. As such, communications are easily disabled during a mine event because of the inherent vulnerabilities to physical damage (Damiano, 2012; National Academy of Engineers, 1970; Yenchek et al., 2011). A true emergency communications system would function regardless of a mine’s physical state. Through-the-earth (TTE) wireless communication technology only requires the use of a single transmitter and a single receiver to achieve point-to-point communication through solid strata. With this capability, TTE systems have the potential to serve as a true emergency communications platform."

Apr 1, 2016

By Frank E. Dalton, Forrest C. Neil

INTRODUCTION The Tunnel and Reservoir Plan (TARP) (Figure 1) was adopted in 1972 as the most cost-effective way to bring Chicago area waterways up to Federal and State water quality standards. TARP will significantly reduce pollution of these waterways and provide flood relief for Chicago and 53 adjacent suburban communities. These communities, covering an area of 971 sq km (375 sq miles), are at present served by combined sewers, which carry both raw sewage and stormwater. Because porous ground surfaces have been covered over in recent years by buildings, streets, and parking lots, stormwater runoff into sewers frequently exceeds the capacity of the sewers. When this happens, sewers back-up into hundreds of thousands of basements, and the overflows on the combined sewers discharge rainwater mixed with raw sewage directly into the area's waterways at 645 overflow points. The result is severe pollution of the waterways and flooding in 53 communities. During particularly heavy rains, overloaded rivers have to be relieved by opening the locks and allowing the polluted waterways to flow into Lake Michigan, the region's water source. Goals of TARP 1. PREVENT BACKFLOWS INTO LAKE MICHIGAN. 2. ELIMINATE WATERWAY POLLUTION CAUSED BY COMBINED SEWER OVERFLOWS. 3. PROVIDE AN OUTLET FOR FLOOD WATERS.

Jan 1, 1981

By Walter E. Heinrichs

This case history really started during the tail end of WWII when two Navy men, both Colorado School of Mines graduates, got together in Washington, DC, while they were assigned to the Office of Navy Petroleum Reserves doing some of the first aerial magnetometer work ever done on a practical oil exploration basis over the offshore area of the Gulf Coast. When separated from Naval Service active duty in 1946, the two men, Walter E. Heinrichs, Jr., and Robert E. Thurmond, tried, unsuccessfully, to form a commercial air magnetometer business. Later they got together again in Jerome, AZ, with Newmont Mining's early geophysical exploration endeavors from 1947 to 1949. Subsequent to the Newmont experience, they jointly proposed a specific mining geophysical exploration and development program to Herbert Hoover, Jr., then president of United Geophysical Co. of Pasadena, CA. Mr. Hoover, in consultation with his father Herbert Hoover and others of his staff at United, particularly Edwin G. Schempf, executive vice president, and Raymond A. Peterson, vice president of research, agreed to establish the proposed program under United's auspices, to be headquartered at Tucson, AZ. The primary objective would be to practically test and develop various mining geophysical methods and techniques while exploring particularly for base metals in the general area of southeast Arizona and southwest New Mexico.

Jan 1, 1991

Steady state simulation has become a highly effective approach to the optimization of existing mineral processing plants and the design of new facilities. Accurate phenomenological models imbedded in user-friendly software packages make this advanced technology available to the mineral processing engineer. The new version 2.0 of the USIM PAC software package contains many improved features, and a new Windows 3 graphics interface. The main features include Objective-Driven Simulation, new fields of application, improved data processing algorithms and improvements in the design and optimization capabilities.

Jan 1, 1992

By R. J. Smith

Hornestake's Mclaughlin Mine is the first commercial application of pressure oxidation pretreatment of gold prior to cyanidation. Inherent to the autoclave process are several liquid/solid separations. Flocculant consumption represents a significant portion of the consumable reagent costs at McLaughlan. This paper focuses on the efforts of the Operating, Metallurgy and Engineering groups to improve thickener operation and minimize flocculant consumption. An operating philosophy incorporating feed solids control, increasing flocculant dilution water and minimizing flocculant solution shear has resulted in a reduction in 1986 flocculant costs of $0.054/t ($0.06 st) versus 1985 costs. Additional changes are projected to result in a further cost reduction of $0.20/t ($0.22/.st) in 1987.

Jan 1, 1988

By A. Mertzanis

The way and methods used for the surface mining of bauxite until the end of the twentieth century in the area of Ghiona, resulted in a significant burden to the natural environment, especially in the cases where it covered extended parts of forests and forest areas as well as important geomorphological formations. The impacts from the surface mining of bauxite which in fact constitute the object of this study relate mainly to the interruption of the natural continuity of the land relief and the alteration of the natural geomorphological activities and are due to: a) the alternating excavations with fronts of great heights, b) the depositions of large volumes of waste materials which originate from the revealing of the ore and c) the dense road network constructed in order to get access to the mine locations.

Jan 1, 2006

By Gerald J. J. Aleva

Lateritization is a surface and near-surface process enhanced by a humid and warm climate and by good drainage. It closely follows the development of the regional landscape. The cyclic landscape development on the Guiana Shield is accompanied by a progressively thicker and more evolved laterite mantle the older, and hence in most instances the higher the planation level. The known, economically interesting bauxite and aluminous laterite eposits of the Shield are restricted to the remnants of the oldest of the Cainozoic planation levels (level I1 and 111).

Jan 1, 1984

By T. Bednarski, T. McCallum

"Physical impurity transfer in solvent extraction (SX) has a significant impact on operating costs, electrowinning (EW) performance, and cathode quality. Some operations use a wash stage to limit impurity transfer by diluting the entrained pregnant leach solution (PLS) to prevent direct transfer to EW. Wash stage operating conditions vary impacting impurity transfer. A number of factors impact dilution efficiency including mixer continuity, wash aqueous acidity, and organic quality. The impact of these variables on dilution efficiency was studied and compared to current industry practice. INTRODUCTION With the exception of iron, impurity transfer in copper SX is due to PLS carryover in the loaded organic via aqueous entrainment and crud movement. The quantity of impurity transfer is influenced by many variables including operating set points, organic quality, and settler housekeeping. Crud management and treatment is a common practice aimed at minimizing transfer of impurities to EW. Crud is a complex solid-stabilized emulsion of aqueous and organic[9]. As such, it contains a large aqueous component and the associated impurities (from the PLS). A common practice is to remove interfacial crud to prevent movement. Additionally, mixer continuity can be altered to enable compaction and improve the efficiency of interfacial pumping[10]. Understanding the factors impacting aqueous entrainment and optimizing the available controls should be a key focus for any operation. Aqueous entrainment in the loaded organic can be impacted by: • Mixer continuity • Mixer organic/aqueous (O/A) ratio • Mixer speed and impeller type • Organic and aqueous depths • Specific settler flow • Use of settler internals (picket fences, coalescing packs) • Organic quality • Design and operation of loaded organic tanks Conventional thought is to run the E1 mixer in aqueous continuity to reduce aqueous entrainment. Generally, O/A ratios close to 1:1 result in improved metallurgical and physical performance. Mixer speeds should be chosen to achieve acceptable stage efficiencies while minimizing over-mixing. Organic depths can be increased in the E1 stage to increase retention time and minimize aqueous entrainment. Settler internals can also be used, but require maintenance to maintain effectiveness. The quality of the plant organic inventory will impact physical performance. Poor organic quality can lead to higher phase disengagement times increasing impurity transfer to the electrolyte. Additionally, the design and operation of the loaded organic tank can impact impurity transfer[8]. Despite the variables that can be used to reduce aqueous entrainment and crud movement, impurity transfer is still an issue in some operations. For these operations with high PLS impurity concentrations, a wash stage may be beneficial to manage impurity transfer. Understanding factors impacting wash stage performance is important to optimize performance and limit impurity transfer."

Jan 1, 2016

Not quite a year ago, during a speech to a group of mining professionals in Washington, DC, the subject centered around the long-range importance of conducting research projects and how much that research needs to specifically apply to health and safety matters in our industry. The point was made about the critical need to work together with government, private industry, labor organizations and academia speaking with a unified voice as we all march into the future together. The fundamental benefits of competitive research were mentioned --to improve our quality of life, to develop our energy resources, to achieve a safe and healthy environment and to ensure long-term economic growth. Very importantly, emphasis was given to the natural link that makes my agency, the Mine Safety and Health Administration, and the National Institute for Occupational Safety and Health --NIOSH --the beneficiaries of each other's findings. Unquestionably, there are lines of separation. The main responsibility of the agency I represent, MSHA, is enforcement of the nation's mine safety and health laws. But we also have an additional responsibility and that is to coordinate and give priority to research in a never-ending hunt for answers.

Jan 1, 1999

By Michael J. Howes

The nature of business in a free enterprise system is to maximise the return on an investment i.e. to maximise the wealth of the shareholders. This is normally achieved within constraints dictated by many agencies, one of which is the health and welfare of the employees. In the mining industry considerable effort has been expended in improvements in this field, however, the major problem still confronting the practicing ventilation or environmental engineer is the determination of what standards he should design for, which satisfy both the economic and health requirement s. Normally the basic health requirements are satisfied by the minimum standards defined in regulations and codes of practice. These are, however, based on an acceptance of a certain risk or lower production potential. A prime function of the ventilation engineer is therefore to financially justify and implement improvements to both standards and systems. The main purpose of this paper is to examine the basis and techniques of providing this financial justification. Changes in existing methods to achieve the same standards but at lower costs are also covered.

Jan 1, 1980

By E.C. Jong

Resumen ¦ Un sistema de comunicaciones “a través del suelo” (TTE) comercial y disponible fue evaluado en una mina de carbón subterránea en la zona Este del Estado de Kentucky. Este estudio de campo fue realizado como parte de una evaluación multisitio mayor de sistemas TTE disponibles. La mina detallada en este estudio se encontraba paralizada al momento de la evaluación, lo que proporcionó la representación más cercana a la realidad del medio ambiente en una mina luego de una operación de cierre. Para este estudio se probaron las comunicaciones superficie a subterráneo y subterráneo a superficie. El despliegue estándar del sistema TTE usando los procedimientos recomendados por el fabricante logró obtener comunicaciones claras y nítidas entre el socavón y la superficie. Otras disposiciones de las unidades arrojaron resultados mixtos. Existen planes para examinar más los fenómenos observados en esta mina.

Apr 1, 2016