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By Y. Zeng

Experiments were performed under batchwise wet grinding conditions with dolomite mineral. The vibration signal was received by an accelerometer and transmitted to a mini-processor. The signal was first stored on a digital tape recorder (OAT) in voltage format during the grinding tests. The original signal was then re-sampled and converted into data format for IBM or compatible personal computer by a digital oscilloscope. The root-mean-square (RMS) and power spectrum was estimated on the time-domain vibration signal. A partial correlation analysis was applied to the frequency-domain signal to detect the non-zero correlation between the frequency bands and the operating parameters. A multiple stepwise regression was used to locate the key frequency bands for describing a particular operating parameter. After vibration analysis, the operating parameters in grinding, for example, the mill speed, the powder filling, the pulp density, the pulp temperature and the particle size were found to be strongly correlated with a few frequency bands. The grinding process could therefore be monitored using the vibration signal.

Jan 1, 1992

By M. Abdelkhalek, M. Hepworth, D. Tao, B. K. Parekh

Pre-combustion coal cleaning and post-combustion flue gas desulfurization (FGD) using lime or limestone are the primary methods employed to reduce sulfur dioxide (SO2) emission from coal combustion. These processes generate voluminous pyrite and gypsum solid wastes that are usually landfilled, occupying thousands of acres of land and creating serious land and water pollution problems due to the release of acids and toxic substances. An integrated process has been developed for the combined utilization of gypsum and pyrite wastes by converting them into useful products including lime, sulfur, and direct reduced iron (DRI). The process includes four major steps. The first step is to concentrate pyrite from coal preparation tailings using flotation or gravity separation. The second is the thermal decomposition of pyrite into pyrrhotite and sulfur. This is followed by the reduction of pyrrhotite with carbon in the presence of lime to produce iron and calcium sulfide. The fourth step involves the reaction of calcium sulfide with gypsum to produce lime. The chemical reactions involved in the process were studied using thermogravimetric analysis (TGA) and X-ray diffraction (XRD)techniques. Process variables studied included reaction temperature, time, reactant composition, and purity of reactants.

Jan 1, 2000

By M. Ericsson

The extractive industries consist of five major sectors: - Mining equipment and services - Dimensional stone - Industrial minerals - Aggregates - Metal mining These industries produce some finished goods but mostly semi-finished products as they feed into other industrial sectors: Basic metals, fabricated metals, construction, chemicals, dyes and pigments, inorganic chemicals, fertilizers, rubber and plastics and non-metallic mineral products. These are the major down-stream industries in this study. Taken together with the extractive industries they form the mineral resource based cluster. The mineral resource based cluster is a substantial part of the Finnish economy: It employs 211 000 persons, 39% of the number of employees in industry. The cluster?s exports account for 20% of industry exports. Value added is 34% of total value added in industry. Investments reach 35% of total industry investments.

Jan 1, 2003

By R. W. M. Lai

The study of flotation kinetics was first reported by Garcia-Zuniga1 in 1935. Since then, literature on the subject has grown with the time. 2-19 Although there is an abundance of flotation kinet¬ics models available in the literature to describe flo¬tation systems, they are mostly of academic interest and are seldom applicable for use in the industrial environment. Several reasons contribute to the wide gap in the industrial -application of the academic models. These include: 1) the lack of generality in the model, e.g., the model is limited to certain size ranges; 14 2) the academic models involve complicated mathematics; 5,6,10,11 3) confusion about the order of the flo¬tation rate, e.g., several authors proposed a first order rate model, 1,15,16 whereas the others propagated a second order rate model: 2,17,18,194) the use of an unrealistic rigid value, such as the use of a maximum recovery of 100%, 5,8,19 which is unrealistic in industrial operations; and 5) the use of graphs that confuse the reader rather than interpret information. 2,3,10 This paper intends to introduce a simple and easy to understand empirical flotation kinetics model along with a way of presenting the model in an informative graphical form, which should stimulate the interest of other practical engineers to become concerned with practical application within the mineral industry.

Jan 1, 1982

By M. B. Daza, B. Lattimer

"Even with modern detection and firefighting techniques, mine fires continue to be a safety concern. However, some underground mine fires can be addressed with the remote application of high expansion foam, reducing firefighter exposure to hazards. The flow of this foam can be numerically or computationally simulated in order to gain a better understanding of its behavior, but rheology parameters are needed as inputs to produce accurate simulations. For this reason, this work studies the rheology of firefighting high expansion foam using a foam generator and Poiseuille –Flow Rheometer. Rheological parameters for foams with expansion ratios between 250-1280 are represented by the consistency index (k) and the power law index (n) due to the results show a strong agreement with the Power Law model for non-Newtonian fluid viscosity. Furthermore, experimental results show that high expansion foam behaves as a shear thinning fluid with a power law index around 0.4 and viscosities in the range of s 0.1 Pa-s and 0.042 Pa-s under shear rates between 44 ??-1 and 187.3 ??-1. INTRODUCTION High expansion foams are called to foams with expansion ratio greater than 200. Expansion ratio (??) is defined as the ratio between the volume of foam produced (i.e. volume of foam solution and volume of gas) and the volume of foam solution used (NFPA 2014). Because of its high expansion ratio, one of the most important application of high expansion foams is to fill or flood large spaces such as hangars, storage facilities and underground mines for fire suppression. The foam can fill large structures using small quantities of foam solution within a short time (Sthamer 2012) (Martin 2012). Although the specific high expansion fire suppression mechanism has not been understood on a quantitative basis, a possible mechanism is fuel isolation when the foam act as a physical barrier between oxygen and the flame. Furthermore, as a consequence of this contact water is evaporated, causing cooling of fuel and surrounding air. Besides, water vapor as product of water evaporation causes a dilution of oxygen concentration available to the fire (Fleming and Sheinson 2012). High expansion foam can be applied remotely by means of conduit pipes or in situ close to the fire. In most of the underground mines scenarios, fires have to be addressed remotely to reduce miner and firefighter exposure to the hazards (Smith et al. 2005). Although high expansion foams should not be blasted and must be deposited directly on the area of application because of their low density (Harding et al. 2016) sometimes it is complicated to apply it directly to the fire due to complex access areas at underground mines. In these cases, foam has to be applied far away from the fire. Despite of this fact there is a lack of knowledge in terms of rheological behavior of high expansion foam under high shear rates (Gardiner, Dlugogorski, and Jameson 1998). Furthermore, there are a few attempts to simulate numerically the high expansion foam flow due to the ignorance of its rheological parameters and its complex behavior. (Weaire 2008)."

Jan 1, 2018

By S. Chatterjee, A. K. Gorai, Sahendra Ram, Kapil Kumar, J. Anil

Extraction of underground coal or mineral by the caving methods leads to surface deformations and the accurate measurement of this deformation is becoming a demanding task. Thus, the study demonstrates a Persistent Scatterer Interferometric Synthetic Aperture Radar (PS-InSAR) technique for surface subsidence measurement. The method was applied to measure the subsidence level over three mechanized depillaring panels with caving at GDK-11 Incline mine, India. The study was conducted using C-band data of Sentinel 1A/B sensors, which captured the data in the descending path from October 25, 2017 to March 07, 2020. The deformation level was measured based on the identified PS points in the specified region. In this case, 12 zones were identified (4 for each panel), based on the observation of permanent scatterer (PS) points. The maximum subsidence level and deformation rate range in 12 zones are −43.12 to −65 mm and −73.8 to 100 mm/year, respectively. The deformation level obtained through the PS-InSAR technique showed a good agreement with those of the field measurement. Thus, the PS-InSAR technique can detect and monitor the subsidence level over the goaved-out panel(s) of an underground mine using C-band SAR data of the Sentinal-1A/B sensor.

Mar 14, 2023

By Yi Luo

Subsidence events occurred over inactive room and pillar (R&P) mines, including abandoned mines or sealed portions of active mines, are classified as unplanned subsidence because of their timing and distribution are unpredictable. When investigating such subsidence cases, many uncertainties exist and disputes often focused on whether the observed structural damages are caused by mine subsidence or other natural or artificial causes. However, solid evidences to identify the causes are often lacking. In order to conduct a thorough and impartial investigation, good knowledge in subsidence theories a

Jan 1, 2009

By G. Jalkanen

Parameter estimation of the inverse distance estimation algorithm is presented. The objective function to be minimized is a sum of squared cross validation errors. The unknowns to be estimated are the exponent of the inverse distance estimator and anisotropic angles and ratios that are used in determining the distances in the algorithm. Examples are presented for both two and three dimensions data sets.

Jan 1, 2009

By David B. Spencer

This paper describes a process for separating non-ferrous metals such as aluminum, copper and zinc, from other residential and industrial waste by means of permanent magnets. Although the separator may be used in the recovery of non-ferrous metals from auto scrap, most of the testing to date has been aimed at recovery of non-ferrous metals from municipal solid waste, especially recovery of aluminum from the heavy fraction of a resource recovery plant. In most resource recovery plants the incoming solid waste material is first shredded and then air classified into a light and a heavy fraction. The light fraction which contains mostly paper, cardboard, etc., can be used either as a fuel for power generation or in the production of new paper products. The heavy fraction which remains consists mostly of glass, ceramics, wood, ferrous metals and non-ferrous metals. The ferrous metals may be removed from the heavy fraction by conventional magnetic separators. After primary shredding, most of the glass and ceramic is fine in size and may be screened away leaving a residue of wood, cardboard, and non-ferrous metals. This residual heavy fraction is the input material for the separator described in the present paper.

Jan 1, 1975

By Venkata Aneesh

This paper examines the desired blast fragmentation results associated with mining fleet performance at Sidney Quarry of Pike Industries, A CRH Company by reducing cycle times and hauling less oversize material generated from the blast to the crusher to increase the overall plant throughput. We are constrained with blast patterns due to the poorly sorted and fractured seams in the quarry, which is angled at 35° NE and dipping at 80° and runs parallel to the Interstate-95 highway on the east of the quarry boundary about 600 ft, making it challenging to alter the blast patterns for optimal yield. We evaluated multiple relationships between blast patterns in conjunction with loader diggability. Results analyzed include the digging hours, fleet cycle times, and the fragment size with the optimized blast design through 3GSM software to arrive at the optimal yield to maximize the crusher throughput. Our primary objective is to focus on safety with efficient cycle times and clean floors & clean face generation for better operational efficiencies. Secondly, to optimize the crusher yield which is an integral part of quarry operation. Further, this paper provides the utilization of 3GSM blasting techniques in quarry applications with computer vision fragmentation analysis and VizaLogix, a fleet management software to analyze the cycle times sampling.

Feb 1, 2024

By William C. McBee

A sulfur concrete technology has been developed by the U.S. Department of the Interior, Bureau of Mines, in which chemically modified sulfur is utilized with suitable mineral aggregates to produce construction materials which are resistant to corrosion by acids and salts. This report presents a summary of the basic technology and results of testing the materials under actual operating conditions in 50 corrosive environments in 40 commercial plants. After 4 years of testing, there was essentially no evidence of material degradation or loss of strength. Regular concrete materials were attacked and in some cases completely destroyed under the same conditions. Testing is continuing to establish ultimate longevity and durability of the sulfur concretes. The materials are finding widespread applications in metallurgical, chemical, and fertilizer processing plants.

Jan 1, 1983

By G. Delagrammatikas, M. Karmis, J. Mastoris

The evaluation of raw materials in terms of quality profile, mineralogical character and mechanical properties is of great importance to the cement industry. The variability of their chemistry and structure is among the decisive design parameters in the choice of any mining, handling and preblending systems. Furthermore, clinker and cement production require sound estimates of the above parameters, to help produce some appropriate and realistic raw mix configurations and achieve minimum standard deviation of the major components. This paper addresses this subject from the perspective of a cement producer and presents the principles of a methodology aimed at optimizing mine planning and process design. Finally, results from case studies on actual sedimentary deposits currently in operation are discussed.

Jan 1, 2002

By B. P. Spigarelli

To meet the growing need for CO2 capture and storage technology, Michigan Technological University is researching CO2 capture and storage using carbonate solutions. The objective of the present study was to increase the absorption rate of CO2 into the carbonate solution without reducing the absorption capacity of the solution. This approach used a polypropylene glycol methyl ether (PPGME) as a surfactant to chemically alter the gas bubble size. Experiments were conducted to study the absorption rate of CO2 at varying surfactant concentrations of 0, 0.12, 0.24, 0.36 and 0.48 g/L. Results showed that as the concentration of surfactant increased in solution, the absorption rate also increased. The CO2 absorption rate increased from 3.45 mmol/min CO2 at 0 g/L PPGME to 3.92 mmol/min CO2 at 0.48 g/L PPGME. This amounted to a 14% increase in the CO2 absorption rate with no decrease in absorption capacity of the solution.

By R. S. Rickard, B. Ball

INTRODUCTION Pyrite responds to the flotation reagents normally used in sulfide flotation systems. For example, it is well known that xanthates are good collectors for pyrite, and cyanide, sulfide and hydroxides are depressants. The particular response of pyrite to these and other reagents is used to advantage in several areas. By careful control of depressant and collector additions, pyrite can be separated from other sulfides by flotation. This is of obvious importance in base metal sulfide flotation where pyrite depression is often required to produce a marketable grade concentrate. Flotation of pyrite has long been employed in gold ore processing, and it appears that pyrite flotation from coal may become important in the future (1). It is probably a direct consequence of this relative ease of separation, plus the low economic value of pyrite, that detailed investigations on the chemistry of its flotation and depression are relatively limited. Gaudin (2,3,4) and others, in the mid-1950's published data on the flotation of pyrite, but detailed or consistent mechanisms were lacking. In 1955, Sutherland and Wark's book (5) was published, in which a large amount of empirical information, especially earlier work of Wark and Cox, was presented. More recently, in 1968, significant contributions have been made by Fuerstenau et al. (6,7) and Majima and Takeda (El. These papers introduced electrochemical explanations of the effects observed with xanthate and cyanide ions.

Jan 1, 1976

By J. Kern, M. Cain, T. Torries

Until recently, the generation of electricity was regulated in all states and the value of generation assets in a regulatory environment for ad valorem taxation were based largely on the book value of the plant plus the rate of return on capital allowed by the state regulatory agency. This method of appraising utility generation assets is inappropriate in a competitive environment because past capital expenditures are not relevant in a competitive environment. However, it is not clear what valuation methods are appropriate after restructuring. This paper identifies key problems and advantages of other appraisal methodologies and makes comments on various valuation and taxation methods.

Jan 1, 2001

By Richard Adsero

The Australian Bureau of Statistics and the United States Bureau of Labor Statistics publish data for a range of industries, allowing a measure of performance to be quantified, called multifactor productivity (MFP), and allowing performance between industries to be compared on a consistent basis. At the time of writing, the last released data was for 2011-2012. For Australia, the plot of mining industry productivity and a basket of the 12 most significant industries in Australia?s economy (including mining) are shown in Fig. 1. For the United States, mining and petroleum and all manufacturing productivity are also displayed in Fig. 1. The trends are as follows: ? The MFP in the Australian mining sector rose 36 percent from 1986-1987 to 2000-2001. There was a 47-percent decline in MFP from 2000-2001 to 2011-2012 (Australian Bureau of Statistics, 2011). ? The MFP in the United States mining sector rose 17 percent from 1986-1987 to 2004-2005. There was a 7-percent decline in MFP 2004-2005 to 2010-2011, (Topp et al., 2008).

Sep 1, 2013

By Bodo Peinemann

For more than 35 years Lurgi has been providing its fluid bed roasters on a world­wide basis. The current total annual capaci­ty of the 250 Lurgi roasters approaches 26 million mt of sulphide minerals, including gold-bearing flotation pyrite concentrates. While the stationary fluid bed has been uti­lized for roasting exclusively, Lurgi has now commercially introduced its Circulating Fluid Bed (CFB) technology for gold roasting in a successful effort to maximize gold re­covery.

Jan 1, 1990

By R. V. Ramani

An improved mine environment is the single most critical factor affecting the health and safety of workers engaged in underground coal winning. A very important subclassification of this wide field is mine ventilation, which essentially deals with 'mine atmospheric environmental control.' To ensure proper mine atmospheric environmental control, adequate quantities of air must flow through working sections in the mine. In recent years much attention has been paid to the fan and its prime movers, but the efficient use of the fan output in the workings has not received an equal amount of investigation. In mechanically ventilated mines friction losses in main airways often account for 70 to 90 percent of the total pressure loss sustained in the system. Also the leakage losses are a serious detriment to the efficiency of mine ventilation systems. It is not uncommon to loose 60 to 70 percent of the air between the fan and the last open cross-cuts due to leakage directly into the return Proper assessment of these losses in simulating and projecting complex ventilation systems is vital. Network analysis of ventilation systems is not new. Scott and Hinsly (1951) presented the detailed mathematical framework. Since then work has been done in adopting this technique to analog, and within the past few years, to digital computers. Development of computer programs to solve ventilation network problems has been reported in United Kingdom, Japan, U.S.S.R., South Africa, Germany, and the United States. The purpose of these programs is to serve as an experimental mine wherein analysis of proposed alternatives or ventilation planning can be tested. The great power of the computer as a planning tool lies in the ability to input empirical or Projected data into programs with predicting ability. But, however good a computer program is, unless fairly accurate input information is available accurately assessing the engineering factors of the ventilation system, the output will be suspect. Thus, to simulate and project mine ventilation systems, good estimates of leakage and friction factors are important. Yet, relatively little work has been done in the past three decades to determine these more realistically.

Jan 1, 1973

By G. W. Mannard

The large massive sulphide deposits present a formidable challenge to the economic geologist. They represent such huge concentrations of iron, sulphur, base metals and precious metals that it is difficult to conceive how they were derived from the crust or mantle of the Earth. The problem of the origin of massive sulphide deposits has generated a geological controversy which has lasted two hundred years and shows no sign of abating. The economic incentive to solve this problem is great, as the massive sulphide bodies are the moat important source of the world's zinc, lead, and silver, as well as yielding large amounts of copper and gold. Using the criteria of abundance, size, age distribution and gross value of contained metals, the predominant sub-group of the massive sulphide deposits is that which comprises the crudely conformable pyritic (or pyrrhotitic) deposits which occur in stratified volcanic and sedimentary rocks or their metamorphosed equivalents. Examples of this sub-group are: the Buchans, Bathurst, Noranda, Kidd Creek, Flin Plon and Sullivan deposits of Canada; the Mt. Isa and Broken Hill orebodies of Australia; the Cyprus, Rio Tinto, Meggen and Rammelsberg deposits of Europe; Ducktown and the United Verde in United States; and the Kuroko deposits of Japan.

Jan 1, 1973

By Wern-ping (Nick) Chen

In concrete lined tunnels, formwork removal timing may be controversial. Contractors seek to strip the form as soon as possible, and designers seek to keep the formwork in place as long as practical to protect the fresh concrete. Formwork removal timing is normally specified as a function to its insitu concrete strength. This approach may work for smaller diameter tunnels, but fallacy occurs when applying this approach to larger diameter tunnels, since a larger diameter would experience more displacement than a smaller diameter tunnel from its own weight. Excessive deformation may fail a tunnel to meet its roundness criterion and overstress the lining causing cracking or falling from the crown. This paper presents a contractual mechanism to mitigate this issue.

Jan 1, 2008