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By Ingvar Janelid

During recent years, numerous articles have been published regarding theories and practical applications of sublevel caving. The reason is the great interest this method has created through its possibilities of standardizing and mechanizing operations and equipment. Other advantages are that the method can be adapted to orebodies of different shape, size, strength etc., and especially that working conditions can be made safe and relatively comfortable since all work is carried out in drifts. As is well known, the disadvantages or sublevel caving are that ore recovery hardly exceeds 85-90 % if waste rock dilution is to be kept below 20-30 %. Therefore, the main research and development work has been concentrated on parameters which can affect and reduce these disadvantages. This paper deals only with principles and problems which apply to large, massive orebodies. The problems with narrow, vertical or inclined orebodies are so different that they require a special handling. In my opinion, the intense research and development work during recent years, combined with practical experience, has given enough knowledge of the influence of different parameters, so that normal sublevel caving can be efficiently planned.

Jan 1, 1975

By Mahmoud Sepehrmanesh, Verya Nasri

The purpose of this paper is to outline the advantages and disadvantages of single tube and twin tubes for subway systems. Different aspects such as diameter of the tunnel (tunnel spaceproofing), configuration of subway line and stations, impacts on passenger safety and evacuation, ventilation system as well as rail system for each solution were evaluated and compared. In addition, a multi-criterion approach is established to facilitate the decision making for these two different subway systems. The practical example of a mega project has been discussed and the details of the decision-making process has been explained. This proposed multicriterion can be used to facilitate selecting the best subway system in any urban areas.

Dec 1, 2022

By Benjamin K. Pocock

When considering alternative equipment choices in mill or process flowsheets, it is important to determine both capital and operating costs of such equipment as well as other possible savings related to downstream operations. This paper presents a few case studies and shows cursory guidelines for the selection of equipment for new installations or in the retrofitting of existing plants. Based upon recent plant experience, suggestions are given to improve the operation of clarifiers, thickeners and vacuum filters.

Jan 1, 1986

By Roy H. Werner

The environmental demands on the mining industry coupled with rising production costs have created a need for a low cost sludge removal system. The HYDRA* system meets these demands by offering a unique means of removing settled solids from the bottom of a clarifier or a thickener. This underflow system combines experience and proven concepts to form a low cost sludge removal system. The HYDRA system incorporates a flexible design that can be adapted to any settling area. The components are readily available and cost less than a conventional clarifier or thickener. Existing technology developed by preparation engineers provides for retrieval and recovery of mine preparation plant refuse. However, past retrieval methods have been extremely costly. The HYDRA system, because of its low cost, makes the complete process of retrieval and recovery economically feasible. This allows wasted resources to be converted to a saleable product.

Jan 1, 1975

By D. Gove

All mining operations using trucks have a common need to properly match the number and size of hauling units (trucks. wagons. scrapers. etc.) to a loading unit (wheel loader. hydraulic shovel/excavator, cable shovel. push tractor. etc.) to provide the best possible fleet match. Optimizing fleet match minimizes the cost per unit of material moved by that fleet. As haul conditions change (haul length. grade. or rolling resistance), there may be need to adjust the number of trucks to maintain the optimum fleet match. Fleet Production and Cost is a tool which, among other things, can be used to optimize the truck-loader match.

Jan 1, 1994

By L. R. Chirinos

The Tintaya mine of BHP Copper, located in Southern Peru, includes a copper oxide deposit hosted in a mineralized skarn zone. The ore contains large amounts of clays and high acid consuming species resulting in low heap leaching performance. A treatment scheme was proposed that included a wet screening separation. The coarse fraction would be treated by heap and the fines by agitation leaching. The dissolved copper would then be recovered through solvent extraction and electrowinning (SXEW). Testwork determined the optimum heap leaching conditions to treat the oxide in on/off pads of 3 meter height with an initial acid cure followed by variable acid strength during irrigation. The method resulted in a reduced acid consumption and good copper recoveries.

Jan 1, 1997

By Robert D. Schmidt

The Cyprus Casa Grande Corporation has provided Bureau of Mines researchers with an opportunity to investigate the hydrology of leaching an in place copper ore deposit. Hydrologic investigations of underground in situ copper leaching are being jointly conducted under a cooperative agreement. The hydrologic concerns of leaching operations at the Casa Grande mine focus on maintaining adequate solution injection and recovery rates, and on distributing the injected leach solution effectively within the ore deposit. Hydrologic considerations underlying these concerns relate to the permeability of the oxide ore zone during leaching, the unsaturated condition of the deposit prior to leaching, and the constraints imposed on in situ hydrologic design by the underground mine setting. The investigation involves monitoring of flow and pressure conditions in 58 injection and recovery wells, estimating permeability conditions using a hydrologic model, and on-site testing of hydrodilation and airlift pumping. Transient, fracture-controlled permeability is determined to be the dominant hydrologic consideration. A statistical modeling procedure has been developed for estimating changes in permeability during leaching. Flexibility in well design and operation is essential for accommodating the changes in fracture permeability that occur during leaching.

Jan 1, 1990

By Thomas M. Larimer

Prior to April, 1961, the coal charge to Clairtonts coke oven batteries was 3" x 0" mine waslied coal having approximately 6.0% to 7.0% moisture. Even at this size and moisture content, the arching, rat-holing and hang-up was excessive and the effective live storage of coal was only 60% to 70% of the rated capacity of the coal bunkers, depending upon the moisture of the coal. In addition, many production delays were encountered in the time and methods required to fill the larry cars. The need for an improved metallurgical coke led to the introduction of pulverized coal to a portion of the plant in 196 1. When the full potential of the pulverizing equipment was realized, we were able to serve seven batteries in our second unit of batteries with pulverized coal through two coal bunkers. The discharge hoppers of these bunkers were equipped with air vibrators to assist the flow of pulverized coal into the larry cars. The vibrators were helpful in this respect but required considerable maintenance and caused damage to the bin plates.

Jan 1, 1968

By Gonzalo Barrientos

Instrumentation and observation of real mine structures helped define the pressure arch at White Pine, a large copper mine in sedimentary rocks. The pressure arch, which is attributed to inherent horizontal stresses, is used in the design of mine openings.

Jan 1, 1969

By Charles A. Hickey

The dining industry game tome Spruce Pine area a few years after tine Civil War. Two Yankees came down from Massachusetts to mine sheet mica to sell to the stove manufacturers for windows in heating stoves. At this time the method of mining was very crude; it was done only with pick and shovel. They were mining mica from the soft veins. Later they progressed to hand grilling and blasting. Hand drilling was quite an art in the area. One man would hold and turn the steel while one or two other men would drive the steel with hammers. In shaft raining, the muck and water was removed by hand winches called windlasses. About 1920 air compressors and jack hammers came into use. These were perhaps tide greatest improvement that has ever come to the area's mining industry. Later carne gasoline hoists, air drive water pumps, and all electrical equipment. Mica mining has, for the past few years, been very modern and efficient.

Jan 1, 1962

By William H. Dresher

A study has been made of the reaction mechanisms occurring during the salt-roast process to form water-soluble sodium vanadate compounds from the vanadium oxide compounds present in vanadium-bearing ores and concentrates. Two reactions have been identified, either of which lead to water-soluble compounds--oxidation of sodium chloride by water vapor and. oxidation of sodium chloride by oxygen. The former reaction has been found to be predominant in the salt-roast process. A kinetic treatment of the data has shown that for the formation of sodium metavanadate the rate-controlling step in the reaction, in which sodium chloride is oxidized by water vapor is the decomposition of a species containing water and sodiumm chloride, on the surface at the gas-solid interface. For the formation of sodium pyrovanadate, the rate-controlling step is the decomposition of a species containing water and sodium metavaradate on the surface. The transportation of water through the system, perhaps as a sodium chloride-water complex or a sodium metavanadate-water complex, and the actual chemical reaction are relatively fast compared to the initial surface decomposition step. A similar treatment on the data for the oxidation, of sodium chloride by oxygen has shown that the rate-controlling step, is the actual transportation of oxygen from the gas-solid interface to the reactive site. This transportation is by a sequence of two diffusion processes. Transportation during the early stages of the reaction is by the diffusion of oxygen through a continuous layer of reaction product. After, the first few minutes of reaction time a second diffusion process begins and is continuous for the remainder of the reaction. This second diffusion process involves the diffusion of oxygen, through a layer of reaction product that has developed voids around which the oxygen must diffuse. The hindering, nature of this latter process causes the rate of transportation of oxygen to the reaction site to be considerably slower than by the simple diffusion mechanism initially followed. A thermodynamic treatment of the data has shown that the energy of activation for the decomposition of the water-sodium chloride species on the surface is -12.1 Kcal. per mole. For the decomposition of the water-sodium metavanadate species on the surface' the energy of activation is -15.1 Kcal. per mole. The results of this study indicate the limiting mechanisms of the basic reactions occurring during the salt-roast process. These results suggest what variables should be examined in applying this information to actual plant operations.

Jan 1, 1961

By W. L. Freyberger

In many papers concerned with fundamentals of the froth flotation process, authors have considered the contents of a flotation cell to be comprised of two immiscible phases, the froth and the pulp. I (Of course, each of these phases is in turn made up of several solid phases plus air and water.) This generalized concept of the flotation system can be extended by considering the cell contents to include two phases: an extracting phase, the air bubbles plus the collector, which removes a selected mineral component from the second phase, the ore pulp. Thus, there is an analogy between a flotation system on the one hand, and chemical extracting systems, such a solvent extraction system or a leaching system, on the other hand. Such extracting systems may be operated in cocurrent or countercurrent fashion. This paper includes first a brief discussion on the general nature of cocurrent and countercurrent operation as applied to froth flotation, and then presents the experimental results of flotation of a specular hematite ore by each method, using a tall oil fatty acid as collector. Cocurrent Flotation A conventional flotation circuit involving roughing, scavenging, and cleaning flotation is illustrated schematically in Figure 1. In such a circuit the col¬lector, or extractant, and new feed ore enter together at the head of the rougher circuit, and flow cocurrently to the scavenger circuit where more collector is added. According to this practice, sufficient collector is added to the head of the rougher (and scavenger) so that the final tailings are of low enough grade to be discarded. Since the flow of collector and ore is cocurrent, the process consists of single stage contact between the extracting phase and the ore pulp. If the scavenger concentrate is recycled to the head of rougher, the overall circuit has some of the characteristics of countercurrent flow. In such a case part of the extractant (collector) is added at the discharge end of the circuit, and may

Jan 1, 1971

The main goal of this paper is to present readers with recommendations for choosing coaxial cables appropriate for mining applications of Time Domain Ref 1 ectometry (TDR) to monitor rock mass movements. Prior to discussing the recommendations, mining applications are illustrated with examples and the operating principle of TDR is discussed briefly. Items that affect the result of the monitoring system performance include the coaxial cable selected, the grouting material used, and the installation procedure.

Jan 1, 1986

By Ben H. Daud

The systems optimization approach to mine planning has led to the adoption of a number of mathematical and computer models for short, medium and long range planning of mining operations. In the realm of open pit mine planning, the most common uses of such an approach have been in the areas of optimal pit design and planning of materials handling operations. Since a truck-shovel combination is the most widely used method of materials handling in open pit mines, a number of models have been presented in the past to analyze and optimize such systems. Broadly, these models can be divided into two categories. The simulation model, which is primarily used as an aid in analyzing the performance of either an operating or a proposed haulage system under the influence of externally alterable parameters, and the linear or integer model which is used as a tool for short or medium term optimization of the system under the operating constraints. In the first part of this paper, a brief discussion is presented of the linear/integer optimization models presented in the past, and in the second part a new model is described which is actually a combination of the simulation and the integer programming models. In its bare essentials, the model consists of an integer optimization algorithm, but the constraints are regularly and dynamically updated by incorporating the conclusions drawn from a stochastic simulation model of the mine haulage system. Since the successive optimization is performed by the mine operator who manipulates the constraints to guide the model towards the optimum, the mystical black box approach is minimized and should help in adoption of the model by the mine personnel. Also, by combining the stochastic simulation model and the deterministic integer model, some of the advantages of each are acquired.

Jan 1, 1976

By Immo H. Redeker

Tile Asheville Minerals Research Laboratory is a member of the Engineering Research Department of North Carolina State University. The Laboratory is engaged mainly in applied nonmetallic mineral processing research to assist the North Carolina mining industry. A few out of state projects are handled at times. The Laboratory helped to bring the flotation process to North Carolina feldspar, spodumene, mica and phosphate producers and maintains versatile batch and pilot plant facilities at Asheville. It is of interest that North Carolina has now one of the newest and largest flotation plants at Lee Creek where Texas Gulf Sulphur Company produces 10,000 tons of phosphate concentrate per day, and one of the smallest flotation plants at Pittsburgh Plate Glass Company's fiberglass plant in Shelby, North Carolina where $50,000 per year of platinum-rhodium metal is reclaimed from wasted fiberglass furnace refractories in a tiny flotation operation of pilot plant size. The conservation of mineral resources through improved processing methods has been the object of most of the Laboratory's projects. This work has been extremely interesting and rewarding in many instances. Or, the example of projects for Kings Mountain Mica Company it will be demonstrated how waste could be reduced step by step from 20 tons of waste per ton of product to LO tons of product per ton of waste by improved processing methods. Brick, high grade potash feldspar, and silica sand are now produced from formerly wasted materials. AL this time Laboratory work sponsored by three feldspar companies, the State of North Carolina, and the U. S. Bureau of Mines, is aimed at reducing the amounts of feldspar tailings in the Spruce Pine area. Mineral dressing techniques are applied to reclaim saleable mineral products such as feldspar, mica quartz, and to make more uniform material for possible ceramic and other applications. Processes to produce new products such as sand-lime brick, and lightweight foamed autoclaved calcium silicate building products will be tested.

Jan 1, 1969

By Richard D. Lang

The paper provides an overview of the activities which culminated in the decision to construct a major diamond mine in the north west of Australia. It presents a broad summary of the geological, mining, processing and marketing work which has been required to bring the project to the construction phase. The implications of the development for the world industrial diamond market are also discussed.

Jan 1, 1985

By V. F. Hollister

Copper and gold were discovered in the Copper Canyon area of the Battle Mountain district of Lander County, Nevada, in August of 1866. By 1876 a gravity plant was con¬centrating oxidized Copper Canyon copper-gold ores. The history of mining in the district to 1967 has been summarized by John E. Frost (in press) as a case history of the discovery of the Battle Mountain porphyry copper deposits. His summary is not repeated here; rather, the present case history covers exploration since 1967, primarily for gold ores. Subsequent to the construction by Duval of facilities to mine the porphyry copper deposits in 1967, Duval established a geologic staff at the mine to continue district exploration. The staff was guided by David W. Blake, who acted as chief geologist for Duval's exploration in this part of Nevada. Blake's activities led to the publication of numerous technical articles, including his contribution to the US Geological Survey Professional Paper 798-B. A part of that volume is attached as a reprint (pages 23 through 66) as an explanation of the geological setting of mineralization in the district. The work by Blake and his staff recognized metal zonation in the skarn environment at Copper Canyon, and their studies were incorporated in the development of the Tomboy-Minnie gold deposits that are peripheral to the porphyry. Exploration continued beyond the immediate vicinity of the porphyry and the Fortitude ore zones were discovered. These skarn deposits are described in the attached article by Wotruba, Benson, and Schmidt, published in the July 1986, MINING ENGINEERING. The continued exploration successes at Battle Mountain reflect on the well organized and effective exploration team developed at the mine. The team has provided successive discoveries in a district known mostly for ore bodies that are exhausted in a few years' time.

Jan 1, 1990

By G. V. Henderson

Limestone and Dolomite quarries located near Salto-De-Pirapora, Arroia Grande Gaucho, Conde Francisco and Candioita probably represent the closest, major sources of high quality lime and cement grade carbonate rocks to the major population center of Sao Paulo Brazil. The nearest major city to most of the limestone - dolomite sources is Sorocaba and Palma. All of the mining properties visited during this study are located in the state of Rio Grande Do Sul at approximately -32 degrees south latitude and -52 degrees west longitude, southwest of the major port city of Porto Alegre.

Jan 1, 1981

By D. A. Dahlstrom

Crushing and grinding consumes about 1.3% of the nations produced electrical energy.( Furthermore, only one in the first ten highest consumers comes from an industry other than mineral processing. This is the grinding of wheat to make flour. The other nine are all in the metallurgical industry and are easily the largest consumers.

Jan 1, 1988

By O. H. Rostad

The importance of geology in ore reserve estimation has been stated by several authors. King et, a1 (1982) reported that the geological factor was the key deficiency where serious weaknesses in ore reserve estimation appeared, especially in grade. The foundation for a successful mining operation is an ore reserve estimate that neither overstates nor understates the true situation as to tonnage and grade. Overestimation of reserves can have devastating economic results. Overestimation of tonnage may lead to wasting money on an overbuilt plant or worse yet, if grade is seriously overestimated also, to undertaking an operation that is doomed to economic failure from the outset. Understated ore reserves can result in building a plant that is smaller than optimum which may result in higher unit costs. At worst, understated tonnage of ore reserves can result in a missed opportunity for a profitable operation. Failure of the ore reserve estimator to properly take into account all geologic and allied factors pertaining to the deposit can result in an ore reserve estimate that is overstated either as to tonnage or grade or both. This paper will focus on these factors and will not discuss rules about distances above or below a drift that should be given a classification of proven or probable, etc. Each deposit has its own particular characteristics which often require modification of general rules for defining limits of proven and probable ore blocks that work satisfactorily in another deposit. A number of references are included which discuss some of these problems. Definitions of ore reserve classifications and an illustration are given in the Appendix.

Jan 1, 1985