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By J. H. Van Reenen, H. Thiele, C. Bergman

For some time spirals have been the process equipment chosen to recover metal in the size range 0.15 to 3mm from ferrochrome and silico/ferro manganese slags. Recoveries of metal obtained using spirals are usually about 70%. Spirals are also difficult to control. By combining a novel gate on the Apic pneumatic fines jig with the recently developed Apic classifier, metal recoveries of 76% and grades of over 90% have been obtained for FeCr and SiMn slags in the size range 0.15 to 3 mm. The paper compares classifier operating performance and costs with those spirals for FeCr and SiMn metal recovery from slags. The classifier technology can also be applied to chromite and iron ores and coal fines.

Jan 1, 2004

By Pablo Velasco

The Belize economy recorded modest growth during 1980; the growth of the gross domestic product (GDP) in real terms was between 1% and 2%. At current prices, the 1980 GDP reached $108 million2. This output was largely attributed to the performance of a few industries, mostly nonminerals. Such performance improved significantly the balance of payments situation by reducing the deficit from $19 million in 1979 to $4 million in 1980. The rate of inflation was an estimated 18% in 1980 and would have been greater if not for a conservative monetary policy and price control on a number of essential items. Expert earnings increased $43 million, or 50%, from the 1979 level. After increasing more than 25% in 1979, imports increased only 6% in 1980 to a level of $141 million owing to the decline in investment and stabilization of petroleum prices. The balance of trade deficit was $9.8 million in 1980, a marked improvement from the 1979 level of $45.1 million. The mineral output for Belize accounted for only a fraction of 1% of the GDP. Such activity was limited to the production of limestone, marl, and sand and gravel, all of which were primarily used in construction of the Northern Highway between Orangewalk and Belize City. Mineral resources are deficient or nonexistent in Belize for the majority of metals and nonmetals, although the Government and others continue to believe that petroleum must exist in Belize. The proximity to Mexican oilfields and the growing finds in the Peters area of Guatemala support this expectation. The Government continues encouraging exploration onshore and offshore and offers terms that

Jan 1, 1982

By Mark Colwell, Christopher Mark

This paper summarises the results of a research project whose goal was to provide the Australian coal industry with a rib support design methodology and software tool that could be utilised by suitably qualified colliery staff. The project was primarily funded by Australian Coal Association Research Program (ACARP) and further supported by several Australian longwall operations. The outcome of the project is a design methodology and software tool called, Analysis and Design of Rib Support (ADRS). ADRS is an empirical technique, which recognises that several geotechnical and design factors affect ribline performance and in addition that operational and safety issues essentially dictate the level of performance required. Therefore, the design recommendations associated with ADRS are specific to the Australian coal industry; however the procedure(s) for data collection and analysis could be applied to other countries' 'underground coal industries. Case history data were compiled from 34 longwall and two bord and pillar operations resulting in 204 case histories with each case history data set being defined by approximately 130 individual data fields. In addition monitoring (incorporating stress cells and extensometers) was undertaken at 10 collieries to assess and quantify the effectiveness of different rib support patterns and hardware on rib performance. The monitoring sites allowed for an improved understanding of the mechanisms of rib failure and degradation in terms of its interaction with the installed support and at the various stages of the mining cycle. The design methodology deals with both mains development and gateroad development specific to Australian longwall mines. This paper focuses on longwall gateroads subjected to abutment loading and in particular the travel road which becomes the tailgate of the subsequent panel. The statistical analyses associated with these cases suggested that the level of rib support should be based primarily on the development height and the pillar stress level. The ADRS software guides users through the design process, allowing them to develop rib support plans based on sound science and a broad base of in-mine experience To the best of the authors’ knowledge ADRS is the first systematic rib support design technique to be developed for any country’s underground coal industry. The development and use of empirical models in mining have substantially contributed to improving safety and productivity. ADRS further demonstrates that empirical techniques are particularly relevant and beneficial in dealing with the complexities of geotechnical design associated with underground coal mining.

Jan 6, 2008

By N. Raeis Hosseiny, S. H. Bassir

"Chador-Malu iron ore is one of the most important iron mines of Iran.About 98 percent of Fe in the ore is in shape of Magnetite, Hematite, Martite, aqua oxide of Iron and the other irons are with ferrous silicates, actinolite, cholorite and ferrous dolomites. 1% of Fe has replaced in pyrite. The phosphor distribution in the ore is non-hemogenous and its average in the whole of the deposit is 94%. It is in shape of Apatite.This mine contains considerable phosphor, which makes it useless for metallurgical uses. At this mine the phosphor is reduced in the iron ore at two steps. At the first step, magnetic part of the ore is separated from the gangues and phosphors by magnetic separator. At the second step, the ore is enriched by the flotation methods. Experimental flotation methods to obtain the optimum conditions are as follows:• Effect of Starch as Hematite depressant with ATRAC as Apatite collector• Effect of Sodium silicate as Hematite depressant with ATRAC as Apatite collector• Effect of ASAM as Apatite collector with Sodium silicate as Hematite depressant• Effect of ATRAC (BEROL) as Apatite collector with Sodium silicate as Hematite depressant• Effect of ASAM & ATRAC mixture as Apatite collector with Sodium silicate as Hematite depressant• Effect of Kcarbonate as pH-modifier• Final test to Optimize pH, Collector, DepressantAt this research we have found the optimum circumstance of the flotation of Chador-Malu iron ore in order to decreasing phosphors of iron oxide and floating of Apatite to make pure Hematite.To reach the optimum conditions, some tests were done with different amounts of pH, collector and depressant. The results are as follows:"

Jan 1, 2003

By R. C. Diehl

Coal, fly ash, and flue gas samples were analyzed for mercury (Hg) by double gold amalgamation-flameless atomic absorption spectrophotometry. The purpose of the study was to elucidate the fate of the trace mercury in the coal when the coal is burned. Samples were collected from a bench-scale 100-g/hr combustor, a 500-lb/hr combustor, and three coal-burning powerplants. In all cases mercury was found in the fly ash. The amounts ranged from about 9 to about 70 percent of the mercury in the coal that was burned.

Jan 1, 1972

By L. Holappa

Ferroalloy production is an energy-intensive industrial sector with significant CO2 emissions. In this paper the current situation in ferroalloy processes is discussed from the standpoint of global environmental issues, trends and development. Progress and data of ferroalloys production are frequently compared with the steel industry, which is a closely related sector and the main user of ferroalloys. Emission factors of processes and electricity production are examined as well as possibilities and future scenarios of how to diminish CO2 emissions. As a part of this study a questionnaire was submitted to experts in the field of ferroalloys worldwide to survey opinions on the ferroalloy industry today and in the near future (2020). Eighteen questions concerning raw materials, energy, environmental aspects, by-products and economic aspects were responded to by seventeen experts, the answers were analysed and conclusions were drawn. Keywords Ferroalloys, energy, CO2 emissions, electricity, sustainability, questionnaire.

Jan 1, 2010

By Enrique Ibarra, Manuel J. Mendoza

"Abstract: This paper describes the current state-of-practice for the design of cast-in-place drilled shafts in granular soils under axial loading, addressing recent advances that take into account the surrounding soil grain size distribution and their behavior. The important role of the gravel content in the shaft response under axial loading is emphasized. Usual design approaches in Mexico are described, and the results of load tests from different sources are discussed. The analysis emphasizes the primary contribution of the lateral area of shafts to their axial bearing capacity, raising doubts regarding the common local idea of “point bearing shafts”. Finally, some lines of research are noted to permit advances in the important field of deep foundations. 1 INTRODUCTIONIn Mexico, cast-in-place drilled shaft foundations are widely used to support various structures in the west area of Mexico City, where alluvial and volcanic deposits predominate. Deep foundations are also used in modern construction works located in other major cities of Mexico. In fact, the use of drilled shafts for tall buildings and overpasses in the center of Guadalajara as well as in transportation works related to the Metro and roadways in Monterrey is well known. It is worth mentioning that these same structures have been applied in road bridges throughout the country.Procedures for pile construction in Mexico have been basically the same for the past 20 years (Paniagua et al., 2005); however, modern equipment has been incorporated into the construction industry, including innovations in sludge-drilling technology, control and the quality of the castings. In addition, novel and efficient procedures such as construction with continuous auger displacement piles have been implemented (Auger Cast in Place, ACP) and have begun to be used locally with success (Schmitter and Paulin, 2006).However, it can be argued that the technological developments that have resulted in more efficient construction procedures have not included a breakthrough in the full understanding of the phenomena or basic mechanisms of load transfer from piles to the surrounding subsoil and therefore in supported, tested and practical design methods. This is particularly true when seeking to determine the unit side shear strength of shafts drilled in granular media with gravels, where it has been observed that the commonly used calculations developed for sands underestimate the load-bearing capacity by frictionin a most important way. Due to the above reasons, it seemed appropriate to present in this paper a review of the current stateof- practice in Mexico for the design of cast-in-place drilled shafts, particularly in granular media, highlighting some recent advances and research that takes into account the grain size distribution and behavior of granular soil."

Jan 1, 2014

By D. A. Meyer

The long and arduous process of bringing aggregate produced in Mexico to the Gulf Coast of the United States really began in the 1970s when the first exploratory trips were taken by Vulcan's geologists. It was not until the middle of the 1980s that all of the elements of the project seemed favorable and the largest capital investment in Vulcan's history was given the green light. The history of the project will be covered along with a discussion of the role that market forecasting played in the process. Is this the first of many or a once in a lifetime project? In July 1987, Vulcan and its joint venture partner broke ground in Mexico for a world-class limestone quarry and crushed stone production facility. This project is the largest ever undertaken by Vulcan's Construction Materials Group, with a total cost of over 200 million dollars -a cost shared equally by Vulcan and its joint venture partner, Ingenieros Civiles Associados, or ICA, a diversified Mexican company which is also the largest construction firm in Latin America.

Jan 1, 1995

By Don Langlois, Udo Weber

"The effect of grinding media performance on milling and operational behaviour was demonstrated under different selected milling conditions of calcium carbonate. A variety of grinding media material and bead sizes, along with 2 different stirrer tip speeds, were used in the grinding process to generate a particle size reduction of the calcium carbonate (CaCO3). To determine the optimum milling parameters the collected test data was used to calculate and evaluate specific energy as well as stress intensity under different milling conditions.INTRODUCTIONAs a result of increasing energy costs and raw material prices it is important to look at the efficiency of the manufacturing process. Wet grinding and ultrafine wet grinding in stirred media mills are now a possible cost-effective production step for the processing of industrial minerals and precious metals. The generation of smaller particle sizes (down to micrometer scale) can be advantageous for further production steps – i.e. better liberation of precious metals or improved industrial mineral qualities.In the following, the wet grinding process is investigated under different milling conditions of calcium carbonate. Different grinding media materials varying in specific weight, bead size and stirrer tip speeds are used to determine optimal energy consumption for the milling process.DESCRIPTION OF TEST CONDITIONS AND PARAMETERSMill ParametersTests were performed in a Drais Laboratory Perl Mill PML H/V with an installed electrical motor power of 3 kW. The mill chamber is silicon carbide where as the stirrer and discs are made of yttria stabilised zirconia. The mill working volume is 0.9 l. A screen cartridge with a screen size of 0.2 mm is used to separate the beads and slurry at the outlet of the mill. All tests were performed with a grinding media filling grade of 80% (Mill working volume). The stirrer tip speed was set at 6 m/s and 10 m/s."

Jan 1, 2009

By Christian Wawrzyniak

An analysis method for modeling compensation grouting based on the finite element method is presented. By this method the design parameters of compensation grouting, grouting pressure and grouting volume, can be evaluated. Also the subsidence of a building due to tunnel driving as well as the lifting of the building by compensation grouting can be simulated. The stress changes in the tunnel lining and in the foundation of the building are computed as well. The application of the analysis method is demonstrated on two examples for compensation grouting in combination with construction of tunnels.

By Ramón Alanís, Filiberto Orrante, Andrea Festa, Baldomero Gutiérrez, Fernando Cornejo

"SGS implemented two rules-based fuzzy logic expert applications on two grinding circuits operated by Peñoles Group in Mexico. Both expert systems are based on control strategies that push against process constraints to improve throughput. Based on proven methodologies, the projects also required some new approaches that led to permanent changes to the mill control strategy.This paper provides descriptions of the implementation, operation and performance of both expert systems. It also reviews how improved production rates were achieved through the use of a common set of expert technology tools. An overview of the resulting control strategies implemented on the two circuits is presented. The paper also discusses the identification of the process constraints within each circuit and how these constraints are used within the expert systems.INTRODUCTIONMexico-based mining company Peñoles Group and the Advanced Systems group at SGS, formally known as MinnovEX Technologies Inc., collaborated on the implementation of two expert systems in two grinding plants, both located in Northern Mexico.The primary objective of the expert systems was to increase throughput whilst still maintaining the cyclone overflow product size within an acceptable range. The secondary objective was to achieve a high level of utilisation of the expert technology.In order to achieve these objectives, SGS proposed a proven methodology which leveraged the existing operating and technical expertise at site through the client’s involvement in the design and implementation stages. The in-house operating and technical expertise of SGS was also brought to the project and implemented with the client’s approval at all stages. At both sites the final acceptance was defined upon meeting both process and utilization parameters.The development and deployment of rules-based fuzzy logic applications has matured as a technology and consequently, clear definition of process states and their place in the logic structure to control a given circuit are now transferable. The key to the robustness of the control logic depends on selection and tuning rules for maintaining stability and optimizing a given circuit. Application integrators need to have a standardized approach for timely integration and deployment; a critical component to avoid the common critiques that expert applications are idiosyncratic and difficult to maintain."

Jan 1, 2009

By C. Pelley, S. Kelebek, P. D. Katsabanish, M. Pollanen

A series of small scale tests have been conducted to evaluate the effect of blasting on the grinding resistance of rocks. The samples consisted of homogeneous blocks of granodiorite and limestone while blasting was performed using single and multi hole configurations. Grinding resistance was evaluated using relative ball mill tests, rod mill tests and the SAG Performance Index test (SPI) developed by Minnovex. It was shown that the grinding resistance was affected by blasting. However the effect depended on the final product size. In the case of the coarse grained granodiorite, a negligible effect was observed for grinding below the natural grain size of the rock, while the fine grained limestone exhibited more significant changes, in the range of 13-16%. Grinding of granodiorite in the coarse size range indicated a general reduction of its work indices, as evidenced by the results obtained from the ball mill, the rod mill and the SPI tests.

Jan 1, 2004

Illumination hardware developed in conjunction with previous Contracts H024202l, H0242049, and H0242023 had not been adequately tested in actual underground work situations. The purpose of this contract was to install and monitor this equipment on mining machines and in actual working places of coal mines to gain experience with the use of the lamps and support equipment in the abusive and critical environments for which they were intended. The equipment that was to be tested consisted of the following: a. Lamps -A variety of sizes of permissible fluorescent lamps which operate from 12 volts DC power. These include the following sizes: Model 8, (9 watts) 2" diameter; Model 15/2 (14 watts) 2" diameter; Model 15/3 (21 watts) 3" diameter; Model 20 (25 watts) 3" diameter; Model 30, (28 watts) 3" diameter; and Model 40, (39 watts) 311 diameter. Representative photographs of these lamps are shown in Figure 1-1 and 1-2.

Jan 1, 1976

By W. J. Birch, A. Wetherelt

The scaled-distance model for blast vibration analysis is the standard method employed throughout the surface mining and quarrying industries to model Peak Particle Velocity (PPV) data. Although empirical, the method is widely accepted and through the simplicity of its application and ease of graphical verification is set to remain a popular option. The validity of the technique relies principally on the fundamental parametric assumption that blasting data is normally distributed. Throughout the evolution of scaled-distance modelling, this is an issue that has most often been presumed rather than proven (most likely due to the tediousness of the calculations involved). In the few cases when normality has been given some degree of consideration, the result has been the product of a simple visual inspection of frequency distributions: clearly unsatisfactory. However recently the soundness of this assumption has been brought into question, with obvious connotations for blast modelling in general. This paper considers this fundamental issue and seeks to investigate the normality hypothesis within the blasting context through an in-depth statistical analysis of what possibly can be described as an ‘ideal’ blasting dataset. This being a rare case study concerning an opencast coal site in England, where for the entire life of the site every single blast was monitored and recorded through the use of permanent monitoring stations. This has provided a unique ‘total population’ dataset of considerable size from which the assumptions of normality are put to the test.

Jan 1, 2005

By M. H. Dunn, T. P. Danehy, C. F. Denholm, S. L. Busler

The problems associated with abandoned minelands are so extensive that neither federal, state, or local governments nor the mining industry nor watershed groups can adequately address these problems individually. By combining talents and resources, however, these problems are being solved efficiently, effectively, and economically. Utilizing existing water monitoring data, local public-private partnerships have successfully designed and built passive systems within five weeks to six months which treat discharges up to hundreds of gallons per minute that vary in quality from net alkaline to highly acidic, containing as much as 200 mg/L dissolved iron and 70 mg/L dissolved aluminum.

Jan 1, 2002

By Kazimierz St. Sztaba

"Mineral processing – the first technological stage of utilization of mineral – has a very long history. In particular, it revealed and reveals the continuous development and perfection of technological operations and process organization, comprising not only new design solutions and exploitation procedures but also, for example, perfected systems of control and automation as well as methods of process description and result evaluation. During the recent decades the attitude to mineral raw materials was clearly changed, both to the primary ones, i.e. minerals, and to the secondary ones, such as side products and waste, formerly considered useless and at present more commonly used. This results both from the appearance and growth of demand for more and more numerous components of mineral raw materials and also from the necessity of protection of natural resources, constituting the integral part of the system of sustained development of society.These circumstances, and especially the requirements concerning gaining some components which cannot be separated by means of “classical” (used for many years) technological processing operations and aiming at increasing the technological procedures, evoked the necessity of using new technological solutions, applying other basic operations, also the ones characteristic so far for other processing technologies, i.e. chemical, biotechnological and others.These development tendencies, in general commonly perceived, allow us to formulate an opinion that the former state of tasks and processes of mineral processing is being transformed into a qualitatively new form. It can be assumed that this process was signaled by a situation in which, due to the growing role of technological operations based on physicochemical phenomena (flotation and others), magnetic and electrical ones, etc., one should have observed that the former term of “mechanical processing” became inadequate for the real content of the notion determining the discussed stage of mineral utilization, so the adjective “mechanical” disappeared in most languages."

Jan 1, 2003

By Frank K. McIntosh

Bauxite was first discovered in Tennessee, at Chattanooga, in 1906, during the construction of' the McCallie Street tunnel through Missionary Ridge. Several years later, bauxite was found in sinking a well on the Perry or Isabella Stewart property. These and other deposits furnished a substantial tonnage for the abrasive and chemical industries during the years 1906 to, 1920. The search for domestic sources of war material prompted by World War II brought the Tennessee bauxite deposits to the attention of the Bureau of Mines. During the summer of 1942, James S. Cullison and E. Godwin, geologists of the United states Geological Survey, made a survey of the bauxite deposits of the area. In August 1942, Harold B. Ewoldt, a Bureau of Mines engineer, accompanied by the Geological Survey party visited the area and a drilling program was prepared. Drilling was started in November 1942 and continued until March 1943. A total of 2,519.5 feet in 38 holes was drilled on three properties.

Jan 1, 1949

By Robin B. Dill, Mark Pelletier, Daniel J. Dobbels, Subodh Bhaumik, Daniel J. VanRoosendaal

Although primarily cut-and-cover excavations are required for replacement of the existing elevated I-93 interstate highway through the heart of Boston for the Central Artery/Tunnel (CA/T) project, some mined tunnel construction was also undertaken. The mined tunneling conducted was the 22-m-wide northbound roadway structure which passed below a 20-m-deep operating underground subway station that was built in 1913. The innovative underpinning scheme used to support the subway station during construction resulted in the successful mining beneath the subway station with negligible vertical settlement. Two grouting galleries were carefully mined below the subway structure, and pre-grouting of the granulary, pervious glacial soils and weathered bedrock was carried out from these galleries. The reinforced concrete walls of the underpinning structure were constructed within three stacked drifts that were sequentially mined below each grouting gallery. After 11 cross adits were mined between the grouting galleries, cast-in-place post-tensioned girders that spanned between the stacked-drift walls were constructed to support the subway station. The stacked-drift walls also provided lateral support for the 22-m wide by 29-m long by13-m high opening beneath the girders.

Jan 1, 2001

By R. A. Ozerkevich, R. J. Voisey

"SherrGold's MacLellan V ne is located about five miles south east of Lynn Lake immediately to the east of the Keewatin River. (Figure # 1)The property is accessible by an all weather road, leading north from the provincial highway 391, which links Lynn Lake with the Town of. Leaf Rapids and the city of Thompson to the south.The MacLellan Mine (formerly the Agassiz property) was discovered in the early 1950's and optioned from Comiesa Corporation in 1979 by Sherritt. SherrGold Inc. was formed in September 1985. Sherritt then transferred the MacLellan Mine, 15 other gold prospects in the Lynn Lake area and the old Lynn Lake nickel-copper mill to SherrGold. At the same time Sherrgold entered into a management agreement with Sherritt whereby Sherritt would develop and operate the MacLellan Mine and conduct SherrGold's exploration activities.The ore body as outlined in the original feasibility study is expected to produce in excess of 300,000 ounces of gold and 450,000 ounces of silver over the next 5 years. However the deposit is open to depth and exploration is continuing on and around the main zone and the many satellite deposits.The start of construction of the MacLellan mine and mill was scheduled to phase in with the closure of the Fox copper-zinc mine located 30 miles west of Lynn Lake. The majority of the employees from the Fox Operation were either employed at the MacLellan mine or relocated to Sherritt's Ruttan Operation."

Jan 1, 1987

By W. G. Pariseau

Introduction Caverns of 50 m in linear dimension at depths below 2300 m with a life of more than 25 years are proposed for the next generation of water-filled neutrino detectors. Little precedent exists for excavations in such an extreme environment, although some guidance is available from mining experience at great depths, for example, in South Africa, in Canada and at the former Homestake Mine in the U.S.A. Unlike mining for ore, there are choices available in the construction of such caverns that may mean the difference between success and failure. These choices should be informed by rock engineering principles. Recently proposed guidelines for orientation of brick-shaped caverns where the long dimension is a small multiple of the short dimension indicate that the most favorable orientation is with the long and short dimensions parallel to major and minor preexcavation principal stresses (Pariseau, 2005). Numerical analyses at reduced strength indicate some yielding at cavern walls should be expected but that an equilibrium state is quite possible and is aided by arching the back into a spherical dome when the cavern is an empty cylinder (Tesarik and others, 2002). The same indications of stability occur with brick-shaped caverns. However, the most dangerous situation occurs during the excavation sequence to final cavern dimensions. There are any number of excavation sequences that lead to the same final cavern shape, so there is an opportunity to partially optimize the sequence with construction guidelines that minimize peak stress concentrations during construction. This contribution discusses three practical excavation sequences that lead to the same brick-shaped cavern in the strong, massive Yates formation at the Homestake Mine where considerable rock mechanics data has accumulated through the years(e.g., Pariseau, 1985, Pariseau and others, 1995) and where actual mining on the 8000 Level indicates a strong possibility of successful investment in the next generation of large, deep neutrino detectors. The main results are: (1) a favorable brick-shape is one with dimensions in the same proportion as the preexcavation principal stresses (compressionpositive), and (2) favorable orientation of the most extreme but temporary shape of excavation is also best for the construction sequence. Analysis results from a mix of Homestake Mine data and possible excavation geometry illustrate the advantages of these guidelines.

Jan 1, 2006