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By Nathaniel Arbiter

The development of flotation machines since the first industrial use of the process can be divided into three stages. The first, up to about 1930, was marked by diversity in the means for contacting floatable mineral with the air/ water interface and for generating the interface, as well as in cell design. By 1927 Taggart (1) could list 170 patents covering flotation cells, and he mentioned dozens which were or had been in operation. He divided cells into eight categories according to design, type of separating interface, and where in the cell and how separation took place. These were: (1) Film or skin flotation with wet or dry oiling of surfaces; (2) pulp body process with bubbles generated chemically by pressure reduction, by vacuum or by boiling; (3) agitation-froth processes involving local supersaturation with air; (4) bubble column; (5) pneumatic; (6) cascade; (7) subaeration; and (8) combination and miscellaneous types and processes. Most widely used then were the agitation-froth, sub- aeration, pneumatic types. By 1943 a significant reduction in categories had occurred to the two main divisions of mechanical and pneumatic cells according to whether agitation and aeration were (a) by an impeller with or without compressed air, or (b) by compressed air alone. Cells at that time were still relatively small; the Morenci Concentrator completed in 1942 used 432 1.7m3 (60 cu ft) Fagergrens for roughing 45,000 and later up to 55,000 t/d.

Jan 1, 1979

By G. W. Luxbacher

Coal mine infrastructure is rarely designed solely on the basis of ventilating the underground workings. Instead the optimization of a mining sequence, the minimization of coal quality variation, reduction of coal losses by adapting to property boundaries and geologic structure (seam inclination, roof conditions, coal thickness, etc.) or other similar considerations have formed the objective for mine plant design and layout. Infrastructure development may also reflect a desire to maximize production early in the life of the mine or to permit flexibility in mining according to market conditions. Requirements for coal mine ventilation, established by the 1969 Coal Mine Health and Safety Act, have mandated changes in the traditional concepts of mine plant design in the United States. Mines, in operation prior to the passage of the Act have experienced severe limitations when attempting to adapt the existing mine infrastructure to meet the requirements of the law. In addition the increased quantities of air required, velocity limitations on trolley haulage and belt lines, the establishment of separate intake escapeways and gob area ventilation have com- pounded the inherent complexity in planning mine ventilation systems. Past practices in mine ventilation planning and design are no longer adequate. Given the complexity of today's ventilation systems, effective planning and design approaches are required. As such, the interrelationship between the overall coal mine plant design and ventilation system design is examined. An approach to ventilation system design constrained by global considerations of mine plant design, is presented. The proposed approach is, however, applicable to the design of new mine ventilation systems as well as to the modification of existing systems.

Jan 1, 1980

By Ramkrishna Agarwal

A low grade iron ore is mined underground at Grace Mine using the panel caving method. Most of the development work is located in footwall. The runways for LHD equipments are heavily supported with steel sets on five foot centers. The sets are embedded in two to three feet of concrete. The initial cost of support is one of the largest single costs of production. During the process of ore-win¬ning, supports frequently fail, necessitating expensive repair. There is no systematic pattern to the failure of supports. A rock mechanics program was launched to isolate causes and their relative contributions to the failure of supports. The preliminary results are presented. A typical portion of a runway is instrumented to monitor rock mass movements around the runway and the corresponding response of supports as various mining activities are carried out in the neighborhood. We believe that such a program is a prerequisite to any remedial measure to alleviate pressure problem at Grace Mine.

Jan 1, 1973

By O. Tranbarger

In aging tunnels, wall and roof deterioration can eventually result in defects that must be detected and repaired to maintain safe structural conditions. In investigating tunnel defect conditions, a specialized FM radar system was developed with a programmable VHF and UHF operating sweep range for optimizing the penetration and measurement capabilities. The new FM radar technology was tested in two aging brick-lined tunnels in New York City. Test results showed that FM radar signals could penetrate eight courses of water-saturated brick and that the original steel liner outside the tunnel walls was intact.

Jan 1, 1985

By Bruce C. Trent

In order to effectively model subsidence caused by underground openings, a two-dimensional computer code has been developed which couples near- and far-field response. The near-field is simulated by a discrete element block code and a finite difference code represents the continuum region in the far-field. The explicit equations allow rapid and inexpensive solutions to geometries which may lead to subsidence. Two sample problems are presented which illustrate the important features of the code.

Jan 1, 1979

By Norbert Patzelt, Johann Knecht

Future ore reserves of major gold producers in North America and elsewhere will consist of refractory gold ores. About 60 % of the current U.S. gold production is mined in Nevada. Several of the large gold operations in this state indicate that 40 to 90 % of their future ore feeds will contain refractory gold. To com­pound problems, average head grades for refractory U.S. gold ores had fallen from 8 - 9 g/mt to about 4 g/mt by 1991. In Latin America, 52 % of the gold operations will require milling for optimal recovery. Deeper reserves are, like in North America, refractory. Therefore a special treatment process is needed in order to allow for the gold ore to be leached downstream in a conven­tional cyanidation process for a high gold recovery. There are several options available for this oxidation process like treat­ment of the gold bearing ore in pressure oxidation, in a biooxi­dation or in a roasting plant depending on the reason for the refractoriness. If organic carbonaceous matters and sulfides are the prima­ry reasons for the refractoriness, whole ore roasting is a pre­ferred method for the treatment of this type of ore. Since dry ore is to feed to the roaster, a dry grinding mill is advantageous. For the dry grinding system, the moisture content and the ore char­acteristic is of importance. Those parameters decide the mode of the grinding system. For autoclave systems common wet grind­ing systems can be applied. This paper deals with technical aspects for dry grinding plants and gives an outlook on and pos­sibilities for new grinding systems.

Jan 1, 1996

By Eberhard Stolarski, Michael Tacke

When the oxidized surface gold deposits are mined out, the underlying refractory gold ores become the challenge of treat­ment systems. The size and value ofrefractory gold ore reserves are a function of recovery efficiency and operating cost. The start-up of LURGI's gold roasters at NEWMONT's Carlin site has established whole ore gold roasters as a key to high gold recoveries. The ores from several deposits of the Carlin trend are roast­ed utilizing LURGI / NEWMONT technology, which has achieved gold recoveries approaching 95%. This is in dramatic contrast to the traditional perception that roasting is limited to gold recoveries in the mid 80's. Extensive investigation in pilot scale is required to achieve stable high gold recoveries for most variables in the ore body. The key question for all pilot tests is the classic question of (ROM) run of mine ore roasting or concentrate roasting. All variables are dominated by the leaching/ recovery char­acteristics of the natural ores. The degree ofrecovery improve­ment by roasting / calcining establishes the frame of the eco­nomical conditions. The full range of flexibility is required for the design of the plant to allow for ore variations in heat values, combustible con­tents, agglomeration behavior and off-gas composition. The variables in the ore body influence, therefore, the price of the plant proportionally to its flexibility. Concentrates are usually fairly stable in composition, com­bustion behavior, heat values and particle size since they are a product of the very selective flotation process. Flotation is not the successful process step when the tailings remain high in refractory gold contents.

Jan 1, 1996

By Yuting Xue, Gamal Rashed, Zoheir Khademian, Connor Brown, Khaled Mohamed

Ground falls in U.S. underground coal mines can lead to significant consequences, including loss of life, injuries, damaged equipment, and production stoppage. Improving the safety of the workplace is of utmost importance for mine workers and the U.S. economy. The Mine Safety and Health Administration (MSHA) accident/injury/illness dataset provides short narratives for reported incidents, including ground-falls. The main objective of this study is to develop a framework that includes: 1) utilizing machine learning algorithms to categorize ground-fall incidents from narratives based on the main cause of the occurrence and 2) demonstrating an example of a user-friendly visualization to display injury/fatality trends from narratives in U.S. coal mines between 1983 and 2021. The developed framework was tested on a subset of the data and achieved an average F1-score of 96% in categorizing the incidents. The outcome will help identify areas requiring additional research and innovative solutions to reduce severe occupational hazards.

Feb 1, 2024

By Aarne Visnapuu

Unmodified pneumatic rock drills may have noise levels of 115 to 130 dB at the operator's position. Experimental modifications have been made to a standard drill to suppress the noise from the three main sources: the air exhaust noise, the noise radiated from the drill, and the resonance noise of the steel drill rods. A prototype model developed at the Bureau of Mines, Rolla Metallurgy Research Center, operates at a noise level below 100 dB. A close-fitting case and muffler unit, consisting of a metallic skeleton filled with viscoelastic absorber and having a durable cover, provided both muffling and noise absorption. Damping alloys were used at strategic points in the drill. Drill steel resonance noise was reduced by a constrained-layer treatment on the outside of the drill rod. The singular and combined effects of the treatments are presented in detail.

Jan 1, 1973

By John R. Hawley

Ontario, one of the richest mining districts in the world, is a natural storehouse for much of the earth's fresh water supply. Covering over 344,000 square miles, the surface of this Canadian Province is dotted with 250,000 fresh water lakes and is laced with uncounted thousands of fresh water rivers and streams. The southern portion of the Province, for the most part, is flat or lazily rolling farmland. This is where most of the people in Ontario live. Although it is not a major mining area, southern Ontario does possess important deposits of salt, oil, gas and gypsum. Most of these deposits are being actively worked. Toronto, the capital city of Ontario, lies deep in the southern region. Here the climate is mild and the winters are short. The total annual precipitation consists of 27 inches of rain and 65 inches of snow. Most of the major mining companies that do business in Canada have made Toronto their Canadian headquarters. There are two reasons for this. The first, of course, is money. Toronto is the gathering place of many well- known financial institutions. The second is access. Toronto lies within a few hundred miles of some of the most spectacular mining enterprises that exist in the world.

Jan 1, 1973

By R. K. Mehta, M. G. Bersch

Characterization of an ore or mill product is routinely performed by time consuming and tedious chemical analyses, sink-float separations, etc. Additionally, these types of tests do not provide data concerning the interrelations and interlocking of the mineral constituents. This paper discusses some of the applications and capabilities of the Minerals and Material Science Research Center at The University of Alabama. Back-scattered electron images of coal, oil shale, complex suldfide, and tantalium ores were acquired using a JEOL 8600 electron microprobe with a NORAN (formerly Tracor Northern] 8500 image analysis system. Methods of analysis and typical results are discussed.

Jan 1, 1992

By M. E. Rossi

Reconciliation of production information is critical to evaluating the effectiveness of the predictive models, and to allow for optimization of mining operations. Whether mining open pit or underground, mine-to-mill reconciliations can be one of management's better tools to perform proper accounting, and a very useful evaluation and optimization tool. This paper proposes a set of criteria and objectives for a typical reconciliation program; also presents a stepwise, logic approach to performing reconciliations, and discusses the benefits and costs associated with the up-keeping of the information. It also highlights some of the potential pitfalls involved, and methods used to avoid collecting misleading information. These issues are illustrated with an example of a model-to-mine-to-mill reconciliation program being implemented at an operating mine; the program involves multiple predictive models (Long-term and Short-term block models), different open pit and underground mines, stockpiling, and at least 23 different mill streams. This paper presents the initial results of the program implemented at Minera Michilla S.A.

Jan 1, 1999

By N. P. Titkov

This paper presents the results of laboratory and pilot plant investigations for the development of efficient methods of beneficiating hematite ores from the Krivoi Rog, Kursk Magnetic Anomoly, Olenogorsk, and other localities. The tests included gravity, magnetic (in a high intensity field), flota¬tion, and magnetizing roasting methods. It was possible to develop efficient beneficiation methods depending on the mineral composition of the ore and degree of dissemination of ore and gangue minerals. The paper shows the relationship between the iron silicate and quartz content of the ore and the technologic indices of the various beneficiation methods. Some of the conclusions based on these investigations and the technical and economic computations related to the cost of one ton of pig iron produced from concentrates obtained by the various beneficiation methods are: 1. If the hematite ore is not disseminated uniformly, it is expedient to use a combined gravity and flotation process. Ore particles up to 50 am. in size are beneficiated by gravity (heavy suspension, jigging, and others) and yield a lump concentrate. The middlings from this process are recrushed and floated; 2. Finely disseminated hematite ores, containing small quantities (less than 5 percent) of iron silicates, are most effectively beneficiated by flotation. Anionic (sulphate soap, tall oil emulsion with various foam depressors) as well as cationic collectors may be used. Depending on the mineral and chemical composition of the ore, it is possible to obtain concentrates containing up to 65 percent iron with an extraction up to 94 percent; 3. Finely disseminated, mixed hematite-magnetite ores may be beneficiated by flotation or a magnetic separation-flotation process; 4. Finely disseminated hematite ores, containing large quantities of iron silicates and earthy hematite ores are most efficiently beneficiated by the magnetizing roasting method. This method will yield concentrates containing up to 68 percent iron with extractions up to 90 percent. Although beneficiation by the magnetizing roasting process is costly, it will nonetheless, when employed on this type of ore, yield the least expensive pig iron.

Jan 1, 1960

By J. Appleby

This paper reviews earlier in-plant testing at the Sidbec-Normines pelletizing plant at Port Cartier, Quebec, Canada. It describes the result of the more prolonged use of coke breeze during recent months and in addition, the effects of varying dolomite and coke additives upon the metallurgical properties of the pellet production have been studied. Mention is also made of some brief test work carried out to use peat moss as a carbonaceous additive to the pelletizing process and in particular the plans for future work in this respect. Earlier laboratory pot-grate test work had indicated that a production rate increase of between fifteen and twenty percent was a practical possibility, or alternatively that the plant could be run at design rating with significantly lower energy consumption. These energy reductions were of the order of ten to fifteen percent for fuel and main process fan power respectively. The physical and metallurgical pellet properties for both blast furnace and direct reduction furnace use were little affected by the production rate increases, and were actually somewhat improved when practicing maximum energy conservations. Pellet properties could be further improved by not extracting the maximum energy economy. Two phases of carefully controlled in-plant testing were run to assess the effect of energy conservation under plant conditions. These two phases of testing confirmed that an overall fuel saving of approximately fifteen percent could be realized, with a reduction in the Bunker C oil consumption of about forty-five percent, and a reduction in main process fan power of approximately ten to fifteen percent. The present scope of work is aimed at establishing the use of varying levels of coke addition up to about one percent under normal plant operating conditions.

Jan 1, 1980

By Rolando V. Cuaño

For geostatistical applications, heterogeneous spatial phenomena are better modeled as mixtures of populations. However, the modeling of the constituent populations can become complex. The alternative mixture model offers a simplified approach to the w modeling problem. The model is applied and tested on the Walker Lake data set. Compared to the univariate ordinary kriging model, the alternative model generates less biased block estimates.

Jan 1, 1996

By J. A. Siekmeier

The thickness of the laminated beam modeled in this study is based on bridging potential and TDR measurements. The laminated beam stiffness is based on the effective stiffness of an equivalent transformed section. The maximum deflection of this near-surface laminated beam is compared with the maximum measured surface subsidence. The spreadsheet provides a rational technique to graphically display the character of the overburden and potentially allows prediction of a subsidence factor based on boring logs and the proposed mine plan. The U.S. Department of the Interior, Bureau of Mines (Bureau), utilizes a commercially available computer spreadsheet program in combination with a modified version of Bieniawski's Rock Mass Rating (RMR) system to characterize the geology overlying high extraction coal mines. The spreadsheet program calculates a RMR for each bed based on the lithology, thickness, and engineering properties, which are determined from boring logs and laboratory tests. Once the RMR is calculated the spreadsheet has two major functions. First, the spreadsheet calculates values used to graphically represent the character of each individual bed in the overburden. It calculates an in situ deformation modulus using an empirical rela¬tionship between the modulus and the RMR and then uses this effective modulus along with additional parameters that are based on mine geometry to calculate the bending stiffness and bridging potential for each bed. Second, the spreadsheet creates a transformed section that allows groups of beds to be modeled as an elastic beam. It then calculates a bridging potential for the entire rock mass. The bridging potential of the rock mass is a single value that takes into account both the geology of the overburden and the geometry of the mine. It seems reasonable that there would be a strong correlation between the bridging potential, the overburden response to high extraction mining, and the subsidence ratio. The results presented in this paper focus on the relationship between the bridging potential of individual beds and the deformation measured using Time Domain Reflectometry (TOR). Subsurface displacements measured over seven high extraction coal mines in southern Illinois were correlated with the bed stiffness and bridging potential profiles. Based on these correlations it was evident that the process of caving and subsidence over these high extraction mines involved momentary bridging by individual beds or groups of beds and the ultimate development of a laminated beam near the surface.

Jan 1, 1986

By D. E. Larson

The U.S. Bureau of Mines has developed a image analysis methodology to correlate the energy consumed during the grinding of an ore to the mineral liberation achieved. Energy consumption values are obtained using a laboratory-scale ball mill equipped with a torque sensor, and an automated image analyzer is used to determine the liberation present in ground products. By combining liberation information with energy consumption data an appraisal can be made of the energy required to liberate the mineral(s) of interest. Results of tests performed on a complex sulfide material determined the effects of grind duration on the liberation achieved and the energy efficiency.

Jan 1, 1995

By Gregg J. Hodges

The Stillwater Mining Company, a partnership of The Pittsburg & Midway Coal Mining Co. and Manville Corporation, began commercial production of flotation concentrates from the western hemispheres' only primary platinum palladium deposit at Nye, Montana in March 1937. In the fall of 1987 an integrated pilot plant testing campaign of electric furnace smelling and oxygen? blown converting confirmed the feasibility of further upgrading to semi? refined matte or 'white metal". In the summer of 1990 the production smelter was brought on-line at Columbus, Montana. This paper describes the technology transfer from the pilot to the production smelter. Emphasis is placed on flowsheet development and the scale factors between the test and production furnaces and gas cleaning plants. The metallurgical results of the pilot plant and of the early months of production of the commercial works are also compared.

Jan 1, 1991

By R. E. Musgrove

At the present time Climax Uranium Company recovers vanadium oxide from carnotite type uranium ores in the mill at Grand Junction, Colorado, The flowsheet of this mill is shown in Figure I. Vanadium is solubilized by a salt roast of the slime fraction of the ore and dissolution is accomplished by a water leach. The metal is precipitated from the pregnant liquor as sodium polyvanadate by heating to boiling and adjusting the pH to 3 with sulfuric acid. The sodium polyvanadate, commonly called, "red caken, is filtered, melted, and cast into thin flakes. This fused flaked vanadium oxide is the material which is packaged for sale. Fused vanadium oxide, marketed by Climax, contains approximately 87% V205, 7% alkali oxide, 0.08% sulfur, 0.03% phosphorus, and less than 0.5% Insoluble. This material is of a lower grade and has a higher alkali oxide content than other vanadium products offered for sale at this time. A typical analysis of a high grade vanadium oxide currently offered for sale by another company is 98% V205, 1 - 2% alkali oxide, less than 0.05% sulfur and less than 0.2% Insoluble. The only reagent consumed in the precipitation of the sodium polyvanadate is sulphuric acid. The total reagent cost is 0.58 cents per pound of vanadium oxide produced.

Jan 1, 1958

By D. J. Beeby

California's Surface Mining and Reclamation Act (SMARA) was passed in 1975 to identify and protect mineral resources in areas of high land use conflict and ensure reclamation of mined lands. Under SMARA, aggregate resource availability is quantified and compared to forecasted demand in specific market regions. Fifteen regions studied thus far cover 51,800 km2 (20,000 sq miles) and contain 45 Gt (50 billion st) of high-quality aggregate resources that have been legally designated as "regionally significant," providing a measure of protection previously unavailable. SMARA reports and state testimony at local hearings have supplied objective information and helped reduce conflict in mine permitting decisions.

Jan 1, 1987