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By George A. Lawrence

A new super-large 100 m3 (3500 ft3) pneumatic mechanical flotation cell is now available to meet today's mineral processing challenges. Several innovative design concepts represent a marked departure from conventional flotation cell designs. The radial discharge from the pump action rotor and the overhung vane type stator is contained in a conical bottom round tank with no dead comers. Peripheral launders collect froth overflowing the entire circumference of the tank and these launders are of a hexagonal design permitting cells to be nested together in a honeycomb fashion. The mechanism drive is either a customized right angle gear reducer or a conventional Vee belt drive. Both drive systems are available with an optional variable frequency control system that permits infinite speed adjustment of the rotor in each flotation cell or group of cells. Results of side-by-side comparative testing between three major manufacturers of super-large pneumatic mechanical flotation cells are discussed. These results were obtained at a large copper concentrator in Chile during several weeks of commercial scale testing.

Jan 1, 1995

By Heinz Distelmeier

The New Austrian Tunneling Method was, as is well known, developed from conventional rock tunnelling. In Germany about 10 years ago the NATM began to be applied to partially stable soils by incorporated excavation and support methods to allow its use with these soils. The advantages of this tunnelling technique - adaptability, ecomomy, and quality have resulted in its widespread usage. Today, about 85 % of all mined tunnels in Germany are produced with this technology. This rapid development has resulted in about 40 companies operating within a geographical area about the same size as the state of Illinois that are capable of utilizing the NATM. In most cases German contract/award procedures allow the contractor to develop alternate design and plans. As a result of this flexibility and intense competition, safety factors have been gradually reduced to the lower limit of what could be regarded as demonstrably safe, and the utilization of the NATM has expanded to include higher risk conditions, namely * excavating larger cross sections. * working with less overburden. * work undertaken under less stable soil conditions.

Jan 1, 1983

By S. Kelkar, H. Murphy, Z. Dash

Nearly 30 estimates of the minimum earth stress were obtained from hydraulic stimulation tests in 5 boreholes at depths varying from 0.6 to 4.3 km in jointed granitic rock near the Valles Caldera in New Mexico. This site is located within the transition between the Colorado Plateau and Basin and Range provinces. Stresses were determined from open hole hydraulic fracturing experiments conducted with water at pressures up to 48.3 MPa (surface). The virgin bottomhol e temperatures ranged up to 327°C. Pressure records show no evidence of rock breakdown, indicating injection into pre-existing joints. A typical pressure response consists of an early wellbore storage period followed by linear fracture flow, which then evolves into a steady pressure, fracture extension mode. Shut-in behavior is characterized by a sharp pressure drop followed by a more gradual decay. The minimum earth stress shows a general linear trend with depth, increasing with a gradient of 19 MPa/km. A low stress anomaly occurs from 2490 to 3100 m where the minimum stresses are as much as 28 MPa lower.

Jan 1, 1986

By G. Brofas

The reforestation potential of bauxite mining spoils by seeding was examined on this research work. The experimental plot was established on the location Strofi Koukouvista 5, Ghiona Mountain. The experiment consists of 3 species (Pinus nigra, Robinia pseudoacacia, and Spartium junceum) with 4 sowing treatments and 2 sowing seasons (autumn and spring). The treatments were: (1) broadcasting; (2) broadcasting and soil cultivation; (3) broadcasting with straw mulching and straw binding with asphalt emulsion; (4) broadcasting with soil cultivation, straw mulching and straw binding with asphalt emulsion. Third year results show that spring is better than autumn as a sowing season. Only the Spartium junceum species were found to germinate and survive in autumn. The results are better for all the species on the spring seeding. The most effective treatments for Robinia pseudoacacia and Pinus nigra are 3 and 4 while for the Spartium junceum even simple broadcasting shows good results although the best ones are achieved with treatments 2, 3 and 4. The paper?s findings show that reforestation by sowing could be effective for some species but further experimentation with other species is recommended. Concerning Robinia pseudoacacia, testing of different seed preparation treatments is needed in order to maximize the germination of seeds.

Jan 1, 2002

By Wenhua Li, Tsuyoshi Adachi

Resource nationalism is essentially mandatory government intervention in natural resources businesses by political or economic means in order to benefit the nation and the people. It is attacking the mining industry more and more rampantly by all kinds of means since the twenty-first century. Poor countries who count on a resource-led economic growth usually find themselves trapped into “resource curse”. The harmfulness of resource nationalism for investors is that one event can quickly escalate and lead to a chain of events which make projects commercially unavailable. In spite of historical and theoretical social investigations in the causes of resource nationalism, rare studies engaged in quantification of dominant parameters of it. The objective of this study is to find significant factors that dominate the occurrence of resource nationalism for important metal and energy resources producing countries and quantify their marginal effects. The study applies binary choice logit model for panel data using pooled method. One feature of the research is that binary data set of occurrence of resource nationalism are sorted out by authors referencing U.S. Geological Survey’s reports. The results indicate that high-technology export (% manufactured export), ores and metals exports (% merchandise exports), rule of law (world governance indicator), trade (% GDP), and natural resource rent except forest (% GDP ) dominant the occurrence of resource nationalism for high and upper middle income group countries; government effectiveness (world governance indicator), policy perception index (The Fraser Institute), high-technology export (% manufactured export), and mineral rent (% GDP) dominant the occurrence of resource nationalism for lower middle and low income countries. According to our model, probability of occurrence of resource nationalism in 90 countries are predicted. Top 10 risky countries in 2012 are estimated to be North Korea, India, Honduras, Indonesia, Kazakhstan, Burkina Faso, Mongolia, Cuba, Bolivia, and Peru. The study is a primary trial of researching on resource nationalism and provides some insights for theoretical building and simulation on the issue.

Jan 1, 2017

By N. Roqueñí, J. Loredo, F. Pendás

Impacts of mining on surface water and groundwater occur frequently not only in active mines but in abandoned mines, then the establishment of effective legal mechanisms for the regulation and control of mine waters is a necessary step in order to avoid pollution from mine waters and in consequence to contribute for a sustainable development of the mining industry. Currently there is a lack of a specific European legislation about mine waters and this absence of legislation occurs too at national level in many European countries. This absence of an European specific regulatory framework for mine water pollution questions the effectiveness and the applicability of the current legislation and this fact has led the EC to put forward proposals legislation to adequately deal with environmental and social consequences of mining, and among those proposals is a draft for a directive on waste from the extractive industry that includes provisions for mine water pollution.

Jan 1, 2005

By W. Setzepfandt, J. Henneke

PREFACE Debris disposal can very often be a severe problem and major restriction on tunnel boring projects, especially for small diameter tunnels and in underground mines. Hydraulic transport could provide a suitable solution. Investigations have therefore been made in connection with a full-scale project of 4.8 km length and 2,3 m diameter, to obtain the required technical and economical data for planning an optimized transport system, e.g. for a tunnel boring drivage of 6 - 7 m diameter in underground coal mines. INTRODUCTION The Radau-Tunnel, chosen for the investigations, has been designed for transferring flood peaks between the rivers Radau and Grosse Romke in the Harz-Mountain of Lower Saxony. A DEMAG TVM 20/23 H tunnel boring machine was used to drive the tunnel on a rising gradient of 0,53 %. The rock consisted of shale and hornblende (55 %), granite (15 %), diabase (15 %), chert (8 %) and gabbro (7 %). The project has been sponsored by the Federal Ministry of Research and Technology.

Jan 1, 1981

Various computer packages are now available for balancing data obtained from complex concentration plants. It is well established that the filtered data generated by these programs are statistically better than the raw data. However the degree of improvement as well as the accuracy of the estimated variables depend strongly on the propagation of measurement errors through the estimation algorithm. Therefore, for the subsequent use of the filtered data, their confidence intervals are as important as the data themselves. Variance of filtered variables have been derived in a very general way for any arbitrary flowsheet and when data originate from various sources such as flowrates, chemical assays, particle size distributions and pulp percentages of solids. The theoretical formulae are incorporated in the BILMAT package for mass balance calculation and illustrated on various flowsheets involving grinding, classification and flotation. The validity of the proposed method is discussed by a comparison to a Monte Carlo approach, for a simple processing circuit.

Jan 1, 1986

By Bruno Mattle, Max John

For tunnels with low overburden, the shotcrete lining is the main element of ground support, which is why shotcrete behavior is of prime importance. Following its application, shotcrete not only gains strength and stiffness with time but—if loaded at an early stage—it is also subject to creep which in turn leads to stress relaxation. For two-dimensional FE calculations, a computational modulus of elasticity of shotcrete is to be used. Based on parameter studies it was found that the modulus of elasticity of shotcrete depends on both shotcrete mix and ground behavior. While the Young’s Modulus used for young shotcrete may range from 1,000 to 7,000 MPa, the Young’s Modulus used for hardened shotcrete is best represented by a value of 15,000 MPa.

Jan 1, 2003

By Gary F. Meenan

Continuous pi lot scale dewatering tests compared the performance of the vacuum disc filter with that of the screen bowl and the solid bowl centrifuges. The test results allow the a priori prediction of plant product moisture based on the feed particle size. This information is useful for selecting the best dewatering device for a given size material and for optimizing the dewatering performance of existing plant installations. Quantitative information was gathered on the ability of filter aids to improve the filtration rate of fine coal slurries. A polymeric flocculant and oil were added to the disc filter feed material at various dosage levels. Both filter aids increased the disc filter output. For the coal tested, the flocculant filter aid achieved higher filtration rates at a lower cost.

Jan 1, 1988

By Donald Ross-Watt

Mining project investment concerns the installation of mine capacity for the purpose of generating a stream of future economic benefits. In order to make this type of investment decision, the optimum specifications for the project must first be determined. Then, the economic justification of the investment tin be evaluated based on these specifications. Economic evaluation to guide mining project investment decisions is based on a proposed plan for mining the deposit over its operational life. If single point estimates are made of deposit characteristics and environmental parameters* as the basis for assessing a future stream of economic benefits associated with the investment, a future mining-plan can be optimally fitted to these estimates and, to the extent that such estimates are actually realized, this plan will retain optimality.

Jan 1, 1979

By R. R. Oder, R. J. Gray

We report measurements of the effects of rank, type, and grade of coal on grinding energy and grinding media consumption in a Pitt Mill. The rank of coal has a greater effect on grinding energy than does coal type. The effect of coal grade on grinding energy depends upon the relative grindability of the mineral matter and of the hydrocarbon components of the coal. The mineral matter is primarily responsible for abrasive media wear in a Pitt Mill. The widely recognized HGI test for coal breakage may yield misleading results, particularly for multiple-banded bright and dull coal where the screening procedure used in sample preparation favors the testing of the hardest coal fraction. The work reported here indicates that the Pitt Mill, which grinds the whole coal in a single stage and which yields easily interpreted results, is an excellent candidate for testing coal pulverization characteristics including energy requirements and equipment wear. The measurements of the effects of coal characteristics on grinding energy and on media consumption have been used to estimate the cost of fine grinding in a Pitt Mill. The results, based on a conceptual level evaluation of grinding at the rate of 1 TPH, show that there are trade-offs possible between the cost of energy and cost of media consumption which involve choice of grinding media size. The use of fine-size grinding media to lower grinding energy and to increase throughput can be deceptive because the total cost of grinding must consider both energy and media consumption.

Jan 1, 1992

By R. A. Hodge, J. W. Murray

By an order of the Executive Council of the Provincial Government dated January 18, 1979, a Royal Commission was established under the Public Inquiries Act to: 1) Examine the adequacy of existing Federal and Provincial requirements for the protection of the health and safety of workers associated with exploration, mining and milling of uranium in B.C. and for the protection of the environment and of the public. 2) Receive public input on these matters. 3) Make recommendations for setting and maintaining standards for worker and public safety and for the protection of the environment as a result of the exploration for the mining and milling of uranium ores. At that time,and at the present time in British Columbia, no uranium mines were, or are, in operation. Exploration at a number of sites was under way and one deposit, the Blizzard deposit, with estimated reserves of 1.92 million tonnes containing approximately 4.74 million kilograms of U308 was at an advanced stage of exploration. With our Terms of Reference, and because of the diverse geology of the western Cordillera which could potentially host a broad variety of uranium, deposit types, the Commission was faced with the task of considering environmental and health protection necessary for the potential development of [any] kind of uranium mineralogy situated in [any] of the environments found in British Columbia. Over the past 17 months since that time, much has transpired, culminating in the February 27, 1980 Provincial Government announcement of a seven year moratorium on exploration, mining and processing of uranium coupled with the termination of our Inquiry before completion of the hearings. The Government sebsequently modified its decision to terminate the Commission completely, deciding instead to stop the hearing but allow time for the Commission to gather in the work that had been initiated

Jan 1, 1980

By Ammar Henchiri

INTRODUCTION A current need of the phosphate industry is the development of process technology for treatment of high carbonate content ore. About 75 to 80 percent of the world phosphate reserves (1) are associated with carbonate gangue, which is not amenable to treatment by the existing techniques. Numerous laboratory and pilot plant studies have been devoted to carbonate-phosphate separation. Different techniques were involved (washing, sieving, attrition, flotation, calcination, and leaching). For technical and economical considerations, flotation appears to be an efficient process for this problem. Separation of carbonates (calcite and dolomite) from igneous phosphate is applied in industrial plants in Brazil, Finland, and South Africa. But, for sedimentary phosphate, no industrial realization exists at this time, with the possible exception of some plants in China. The main problems with sedimentary phosphates are: • high substitution by CO3-2 and F- for P04 -3 in the apatite lattice. • larger surface area of the phosphate particles because their surface is porous and irregular. • tendency of sedimentary minerals to produce more slimes in conditioning than the crystalline minerals, hence, larger dosages of collectors are required for sedimentary minerals. Investigations reported in the literature indicate that most processes developed for sedimentary carbonate-phosphate separation involved inverse flotation of carbonates using fatty acids as collectors (2), (3) associated with phosphoric acid (4), monosodium phosphate (5), F- (6), or SiF6 -2 (7) as phosphate depressants. Later investigations, conducted by A. Henchiri and G. Baudet (8), (9), (10), (11), (12), (13) in the BRGM technology department, of phosphoric esters revealed that these reagents are selective collectors for carbonate-phosphate separation. The above investigators developed a process which used phosphoric esters to collect carbonate minerals and sulfuric acid or sodium fluorosilicate as depressants for phosphate. Extensive comparative tests for different processes on the same phosphate sample show that the process developed at BRGM is one of the most promising methods proposed for sedimentary phosphate-carbonate separation. It should be pointed out, however, that phosphoric esters make abundant froths. The handling of these excessive froths will be a problem in an industrial-scale plant. This paper outlines test work performed in order to optimize and to improve the efficiency of the flotation process on a sedimentary phosphate ore selected from the Sra Ouertane orebody. The Sra Ouertane flotation process, illustrated on Figure 1, first removes carbonate minerals by inverse flotation and then recovers phosphate as a froth product, leaving quartz as a cell product.

Jan 1, 1993

By Gary Beerkirkcher

INTRODUCTION The mine hoisting equipment that is selected and installed at a mine is for the lifetime of the mine and, therefore, it is extremely important that a proper choice be made. Several types of mine hoist designs, including double drum hoists, single drum hoists, friction hoists, and various special designs of these, are available to¬day. Each has advantages and disadvantages and they should only be used in suitable applications. Drive systems for mine hoists must be evaluated together with the mechanical systems for each hoist application. It does not make sense to properly select the hoist mechanical system and then choose a drive system that turns out to be a bottleneck. MINE HOIST TYPES There are two basic types of mine hoists available in the world today: the drum hoist, on which the hoist rope is actually stored during the hoisting cycle, and the friction (Koepe) hoist, which merely passes the rope over the wheel during the hoisting process. Drum Hoists Single Drum Hoist: A single drum hoist (shown diagrammatically in Fig. 1) can be used as a service or production hoist with the cage or skip in balance with a counterweight (Figs. 2 and 3). It can efficiently service one or more levels, since the location of the counterweight at any time is not important. As a pro¬duction hoist with skips in balance, the single drum hoist is best used for single level hoisting. All rope adjustments for proper spotting must be done manually for the single drum hoist. This has to be done periodi¬cally to compensate for rope stretch. A variation of the single drum hoist is the divided drum hoist. If multilayer winding is necessary, the single drum hoist must have a divider to allow a sep¬arate compartment for each rope. If a counterweight is used with a divided drum application, the counter¬ weight rope can be wound on a smaller diameter (Fig. 4). Consequently, it moves a lesser distance than the main conveyance and rope adjustment problems are re¬duced. Double Drum Hoist: A double drum hoist in oper¬ation is shown in Fig. 5. Double Drum Hoist With One Drum Clutched: As a service hoist with cage and counterweight, a double drum hoist with one drum clutched (Fig. 6) can serve several levels efficiently. The advantage of having the clutched drum is that it allows rapid adjustment of ropes due to initial stretch. Some users may prefer the single drum hoist with manual rope adjustment, while others consider the added expense of the second drum and clutch is justified to make rope adjustments quickly. The value of this feature for a particular application should be discussed with the hoist manufacturer. As a production hoist with skips in balance for a multi¬level operation, the clutch can be adjusted for efficient hoisting from any level. Double Drum Hoists with Both Drums Clutched: There are also double drum hoists that have both drums clutched (Fig. 7). The main advantage claimed for this type of hoist is that if something happens in one of the two compartments, the hoist can operate in the other compartment to raise and lower men and sup¬plies. This feature is particularly favorable if there is only one shaft entrance to the mine. Multiple Drum Hoist: The multiple drum hoist, a South African innovation, is a type of drum hoist about which everyone should be aware. Basically, it uses two hoist ropes per conveyance which at great depths per¬mits use of smaller ropes and smaller drums. There are none in use in the United States today. However, they should be considered in very deep mines. Friction (Koepe) Hoists This hoist (Fig. 8) was introduced to the mining world by Frederick Koepe in 1877. The basic prin¬ciple of the friction hoist is that the hoist rope passing

Jan 1, 1982

By J. Nowak

Polish power industry is based on brown and hard coal combustion and transferring the heat into electric power. Over 99% of lignite is used as a fuel in power plants. Lignite is mined on in open pits. Therefore very deep (for example 300 m in Belchatow open pit) excavations having great volume are formed. Thus such type of mining has the impact on land degradation. In order to reduce this effect, at the earliest possible moment the cap rocks are dumped in the pit but at the safe distance from the mining face. Due to the big amounts of lignite delivered to the power plant, there are shortages of solids for filling the pit after completing the mining operations. Geotechnical properties of dumped combustion by-products depend on the lignite type, combustion technology and ashes haulage methods. The paper presents lignite combustion methods used in Poland and their impact on properties of ashes and methods of their transport determining the parameters of dumped wastes. Geotechnical, physical and chemical test results concerning transport and deposition of hydraulically active ashes from the Belchatów power plant are presented. The critical role of geotechnical properties in selecting the deposition technology and post mining management of open pit excavations was showed. The importance of filling the post-mining spaces for restoration the useful function of brown fields and for neutralization of negative effects of mining activity, was underlined.

Jan 1, 2006

By A. Pavlidis

This paper investigates variations of lignite quality attributes with geostatistical methods. The study focuses on lignite from the Southern Field in the Greek province of West Macedonia. The targeted quality variable is the ash water-free content (AWF). A geostatistical model is constructed based on data from 480 drillholes (approximate drill hole spacing of 250m). For each drillhole, the vertical average of the AWF is calculated. The coarse-grained AWF is then modeled as the superposition of a trend surface and fluctuations. The spatial dependence of the fluctuations is modeled by means of the experimental variogram. Kriging estimators are used to determine the AWF values on a rectangular grid, and the uncertainty of the estimates is calculated. Implications of the analysis for the variability of the produced lignite are discussed, and recommendations for additional drilling are proposed.

Jan 1, 2006

By J. West-Hansen

The problem of long-term production scheduling in an underground coal mine is approached through the concepts of sequencing theory. Based on a typical layout of mining sections, the principles for the approach are: 1. The definition of mining sections as jobs, and mining methods as machines. 2. The reduction of the overall mining activity to the general problem of nonpreemptive scheduling of precedence related jobs on parallel machines. 3. The simplification of the layout to a general type directed network with the nodes representing jobs and the arcs representing precedence relations. 4. The determination of a feasible and near-optimal job schedule given the objective of maximizing the total net present value of the jobs. A general scheduling heuristic is being developed for implementation on an IBM personal computer (PC) as part of an interactive computer system for long-term production planning.

Jan 1, 1986

By Peter J. Suardini

Over the last few years, researcher have been working on improving procedures for fine-coal (minus 150 microns) washability analyses. The effort was stimulated by past difficulties in obtaining accurate and reproducible results from the various commercial laboratories providing fined washability services. This paper contains the results from fine-coal washability testing, performed by Process Technology, Inc. (PTI), as part of a U.S. Department of Energy (DOE)-sponsored project. The testing focused on comparing the performance of a number of media options (i.e., aqueous solutions and organic solvents), as well as evaluating the impact of a number of procedural steps on separation performance. The paper summarizes PTI's recommended washability procedures for various size fractions and ranks of coal, and makes recommendations for future studies of certain phenomenon, such as void penetration and particle density changes, which are not well understood.

Jan 1, 1995

By Jodie Robertson, Isabel Barton, Cristian Caro

Prior to mining, all rocks contained in a mineral deposit must be placed in one of several categories known as ore types. Each ore type describes a different way that the rock will behave in processing. The ore type determines which process stream a particular mined unit will be sent to, sets expectations for process engineers and metallurgists, and forms the basis for recovery predictions and production estimates. At first, ore types are assigned mainly by geologists based on visible geological criteria (dominant ore mineralogy, estimated grade, rock type, alteration type). As metallurgical tests are carried out and process data accumulate, the resulting criteria may be factored into the ore typing process, typically as assays and recoverable metal using the relevant process(es). Other variables may also be incorporated into ore typing at operations if they are particularly important, such as grindability, preg-robbing, gangue reagent consumption, and the presence of especially deleterious minerals such as talc or smectite. The mine operation department may also redefine ore types and/or process destinations based on economic criteria. A “best” ore type is designated that (in theory) best describes how the rock will behave in processing. Codes representing this ore type are entered into the drill-hole database, then interpreted on cross sections and level plans, and finally added to the block model. Ore types are iteratively reexamined and adjusted over the life of a project. Major difficulties in effective ore typing are (1) lack of communication between geologists and metallurgists, (2) the imprecision inherent in imposing clean categories on messy natural systems without discrete divisions, (3) the need for ore types to provide useful information for a wide range of processes, (4) difficulties in scaling up laboratory test results to mine production, and (5) conflict among geological, metallurgical, and economic criteria for ore typing.

Jul 1, 2024