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By J. M. Ortiz, J. Haas, W. Kracht, G. Pamparana

This work explores the effect of ore hardness variability on the design of a solar photovoltaic system with battery storage and grid backup, to operate a semi-autogenous grinding mill (SAG). First, a case of two synthetic ore populations was studied, without any consideration of spatial distribution. The mean and variance of the ore hardness (measured in specific energy consumption, SEC) of both populations were subjected to a sensitivity analysis. The operation was evaluated with one and two stockpiles. The latter allows classifying according to ore hardness as a way to adapt the SAG energy consumption to the solar cycle. The results show that using two stockpiles allows achieving a larger autonomy (i.e. less energy imports) at lower total costs, especially when the difference of mean hardness between the two populations is large. The difference in variance (between the two populations) has a smaller impact on the design recommendations. Second, a case study was performed considering the spatial distribution of geometallurgical units. Two cases were considered: (a) brownfield, when there is historical information of the actual variability of the ore hardness; and (b) greenfield, when the system design relies mainly on geometallurgical modeling. Brownfield and greenfield planning result in similar sizing recommendations of the solar power plant, if precise drill cores are available. In this case, geometallurgical modeling is an effective tool for forecasting the energy demand necessary for designing the power plant.

Jan 1, 2018

By A. L. Engel

In the period of 1942-1945, medium-grade, oxidized, lead-silver ore was mined and shipped from the Diamond district near Eureka, Nev. An encouraging tonnage of low-grade ore was developed during these operations and partly blocked-out for future mining. If the low-grade ore could be treated profitably, further development of the district would result, and production of an important strategic metal might be increased. A representative sample of Diamond district ore was obtained through the Reno office of the Mining Division for the studies described in this report. The sample consisted of lumps and fines of a highly altered siliceous rock containing much earthy red hematite and some granular black hematite. Examination with the binocular microscope showed the lead carbonate mineral, cerussite, in seams and disseminated in the hematite. No zinc or silver minerals were identified, and no sulfide minerals were present. Analyses of the ore showed:

Jan 1, 1951

By Michael J. Beus

The National Institute of Occupational Safety and Health-Spokane Research Laboratory (NIOSH-SRL) have developed a Shaft Conveyance Monitoring System (SCMS). Assessment of current hoisting technology has shown that monitoring wire rope tension and conveyance position and load directly from the skip or cage top offers several significant safety, production, and maintenance advantages. The SCMS consists of conveyance position and guide displacement sensors, a battery power supply and charging system, and a new sensor to measure hoist rope tension. This device provides a warning of the occurrence of ?slack rope? a particularly dangerous condition. A 2.4 GHz radio link transmits data to the hoistroom. A reduced scale hoisting test facility has been constructed to test these components prior to field trials. The advantages of monitoring wire rope tension and conveyance position and load directly from a skip or cage top will be discussed. Field tests are underway in full-size shafts to refine the concept and evaluate long-term reliability and maintenance requirements. Application of this technology may result in decreased maintenance costs as well as safer, more productive hoisting operations.

May 1, 2001

By R. R. Tatiya

The following procedure was used to determine cut-off grades: define the orebody profile; plan the stope layout and quantify the work involved; formulate equipment-performance norms; calculate unit costs; input process recoveries and metal prices; and calculate the cut-off grade. Use of the method is illustrated using data from a copper mining complex in India. Results from the study led to the following conclusions for underground mines in general. Cut-off dependent costs vary significantly with the stoping method employed, orebody thickness, the degree of mechanisation and the working efficiencies of the workforce and equipment. This applies even within the same deposit. Sub-level stoping and its variants can be operated at a lower cut-off grade than cut-and-fill and its variants. Thinner orebodies affect cut-off grades adversely, but with thinner orebodies very little further reduction in cut-off grade can be achieved once a certain minimum width has been exceeded. For the same stoping method and in the same mine the cut-off grade varies with the degree of mechanisation. Labour-intensive methods require higher cut-off grades. An allowance for working efficiency should be made when calculating cut-off grades. Higher process recoveries allow a significant lowering of cut-off grades

Jul 1, 1996

By Alfred G. Hoyl

The author, in exploring a virgin area vertically in two known ore shoots requiring decline shaft sinking, drifting, crosscutting and diamond drilling, chose to use electric, electric hydraulic, and diesel rubber-tired equipment. A rebuilt hoist, and electric hydraulic shaft shovel (mucker), hydraulic sinking drills, single boom electric hydraulic jumbo, electric hydraulic LHD, and electric hydraulic diamond drill were used successfully. Slides of the equipment and its use are shown. The advantages and disadvantages of the equipment are discussed, together with costs and production.

Jan 1, 1984

By G. Jenny

The particle size distribution of ground minerals is of decisive importance for downstream processes like floatation, separation, drying or others. In order to optimize the process efficiency on one hand and the final product quality on the other hand an early control of the grinding or classification stage is essential. The ultrasound based particle size analyser OPUS is capable of performing on-line particle size distribution (PSD) and solid content measurement of mineral slurries such as iron ore, copper ore, fluorspar, or quartz sand and alumina directly in heavy and rough process environment. The instrument provides a PSD of 31 size classes and can be applied for particles from nanometer range up to several millimetres. Arbitrary interpolations in between the 31 measured points are available. Typical residue values show an excellent agreement to off-line particle size analysis methods such as e.g. sieve analyses or laser diffraction. OPUS is designed as rugged in-line probe made from stainless steel. The applied technique is independent of product flow dynamics, contamination, optical properties, vibrations, pressures or changes in solid concentrations. The instrument provides all data on the system?s PC or on the process control system by a variety of interfaces.

Jan 1, 2014

By Zhihe Dou, Yan Li, Qiuyue Zhao, Guozhi Lv, Yan Liu, Hongliang Zhao

"Abstract: How to reduce carbon dioxide emissions has become a vexing problem, meanwhile, there exist high energy consumption and low efficiency problems in the existing CO2 capture and storage technologies. For CO2 comprehensive Utilization, this paper researches a new technology of absorbing the CO2 emission with high alkaline calcium or high alkaline wastewater sludge mineralization of calcium and invent a core device for multi-level jet carbonation. The industrial test has been carried out in China Xinyu slag Engineering Co., Ltd. The wastewater flow is 150m3/h in the pilot scale. The prepared calcium carbonate has a whiteness greater than 90%, particle size less than 150nm. The mineralization of aluminum exhaust with waste carbide indicates that the CO2 absorption rate is greater than 99.0%, CO2 concentration in the exhaust gas is lower than 0.08%, the purity of mineralized calcium carbonate is greater than 99.0% and particle size is less than 100 nm.InstructionAccording to the statistic data from IEA (2009), the carbon dioxide discharge from fossil fuel consumption in China has exceeded it in the US by the year of 2007, China, has become the largest emitter of carbon dioxide all over the world. Meanwhile, the economic scale is still on an increasing trend in the next 50-100 years, leading to a continuous increment in carbon dioxide discharge. According to the international energy agency forecasts, the energy-relative CO2 discharge in China will rise to 11,615 million tons, 91.3% higher than it in 2007. In the year of 2012, the CO2 gross discharge has reached 10,000 million tons, obviously higher than the predicted value. It is a tremendous task to reduce the emission. Non-ferrous metals industry is one of the largest emitters of carbon dioxide among the industrial circle, the whole industry might discharge a huge amount of carbon dioxide (over 600 million tons), in which the electrolytic aluminum industry is the largest energy consuming industry and CO2 emitter. At present, the CO2 discharge has focused by the whole world due to the environmental problems it causes; meanwhile, supplement of new carbon source is needed due to the exhausting oil and coal resources, so that various countries in the world are attaching importance of the recycle and purification of CO2. Many countries are studying on the cyclic utilization of carbon dioxide. Gas CO2 is mainly applied in chemical, pharmaceutical raw materials, beverage filling agent, refrigerant, inert medium, solvents, pressure source, the welding protective gas, antioxidant and fire extinguishing agent, etc. Solid CO2 is mainly applied in penicillin production, fish, cream, ice cream and other food storage and transportation at low temperature, etc. nowadays, such methods as absorption method, membrane separation, adsorption, etc. are widely used to recycle CO2, with such problems as high investment cost and technical constraints etc."

Jan 1, 2014

By F. T. Mooney

Introduction The Flin Flon mine of the Hudson Bay Mining and Smelting Company, Limited, is on the interprovincial boundary between Manitoba and Saskatchewan, about four hundred miles north of the Canada-United States boundary. The orebodies are gold, silver, zinc, and copper replacement deposits occurring as irregular lenses of massive sulphides, arranged en echelon, and irregular masses of disseminated copper sulphides in chlorite. The country rocks are of Precambrian age, dominantly lava flows. Development of the Mine The mine is opened by two vertical main shafts- the North Main and South Main shafts- 3,800 feet apart. The North Main shaft has a depth of 2,210 feet and the South Main shaft is completed for stoping operations to the 3,250-foot level (see Figure 1). These shafts are connected by main haulages driven, on the footwall side of the orebodies, at 520-foot intervals down to the 2,210-foot level. No. 3 (subsidiary) shaft is on the footwall side of the orebodies at a point between the North Main and South Main shafts, 2,400 feet south of the former. It has a depth of 3,250 feet and connects with all main haulage levels- with both Main shafts down to the 2,210-foot level and with the South Main shaft on the 2,750-, 3,000-, and 3,250-foot levels. Other openings tO the mine include B North fan raise, the opening due to the recovery of the open pit sill pillar, and several back-fill raises.

Jan 1, 1949

By G. W. Poling

Sedimentation behaviour of siliceous mill tailings derived from a magnetite-chalcopyrite ore in fresh water, fresh water - sea water mixtures and full-salinity sea waters are compared. Results of batch settling tests are presented in the form of settling curves and solids flux curves. The addition of a few per cent of sea water markedly enhanced the zone sedimentation rate due to particle agglomeration caused by a reduction in zeta potential of the suspended solids. The presence of a small amount of residual, previously magnetized magnetite in the tailings also enhanced agglomeration and sedimentation. The significance of these results to submarine disposal of mill tailings is discussed.

Jan 1, 1973

By Terry A. Rightnour

Multiple seam mining is predominant throughout the central Pennsylvania Appalachian coal fields. Wide ranges in individual seam thickness, coal quality, and overburden characteristics are common throughout the region. On typical mining permits, ranging from 404 x 103 to 2023 x 103 m2 (100 to 500 acres), often as many as eight seams are concurrently mined, with each interburden requiring unique economic and environmental consideration in the mine plan. Specifically, this paper presents several planning tools and operational guidelines developed in response to current regulations for the special handling of potentially acid-forming materials as they are related to development and operation of multiple seam mines.

Jan 1, 1984

By Horace Freeman

Introduction This paper is an amplification of the paper presented by the writer at the last (1930) Annual Meeting of the Institute (1), and is somewhat in the nature of a progress report upon the introduction of pyrite into the field of Canadian consumption. The burner installed at the plant of the Canada Power & Paper Corporation, St. Maurice division, has been slightly changed in dimensions and has been put into continuous operation during the past year. As predicted, it has been possible to somewhat increase the steam consumption and at the same time decrease the amount of sulphur remaining in the calcine. The grade of the sulphur-dioxide gas produced has been maintained very steadily at 12 per cent, and sufficient experience has been obtained to determine the renewal cost of continuous operation. The object of this paper now is to encourage the development of pyrite, particularly by-product flotation pyrite, as it is shown that there is a very definite field in Canada for this material and that all the previous objections to the use of pyrite have been overcome, and that the use of the material in practice in paper mills has been developed to such a point that the operation of manufacturing the sulphite cooking-liquor is as simple as, or simpler than, the present style of operation with the use of sulphur.

Jan 1, 1931

By N. P. Reddy

This paper describes an experimental setup for multiple-fan ventilation systems at the ventilation laboratory of the WVU Department of Mining Engineering. Housed in a 30 ft by 70 ft room, the experimental setup consists of three 18 in. variable-speed axial-flow fans, the 18 in. diameter fiberglass tubing and fittings for arranging networks, and the pitot tube measuring and data acquisition system. The fiberglass tubing and fans can be organized into the non-planner network of two fans or three-fans. It is mainly designed for studying the characteristic curves, operating points, and fan stall for the multiple-fan ventilation system.

Jan 1, 1992

he leaching behavior of palladium in ammoniacal solutions has been investigated by using the rotating disk technique in an autoclave. The study included the effect of rotating speed, temperature, oxygen pressure, composition of ammoniacal solutions, and catalyst on the overall leaching rate. The dissolution of palladium in ammoniacal solutions was discussed in view of the thermodynamics and a kinetic model. Even though the potential-pH diagram suggests that palladium metal can dissolve in ammoniacal solutions at room temperature, it was found that the dissolution was too slow at temperatures below 100°C but was significantly improved at higher temperatures. It was also found that the rotating speed of palladium disk had no effect on the leaching rate. The apparent activation energy was found to be 69.7 kJ/mole. Based on the results obtained, it is concluded that the dissolution of palladium is controlled by chemical reaction.

Jan 1, 1997

By B. Zeifert, C. Martínez-Morales, A. Romero-Serrano, A. Pineda-Rivera, H. Martínez-Gutiérrez, G. Diaz-Sandi

In this work, the effects of CaO/SiO2 ratio and the FeSO4 and FeS2 contents on the stability of the mineralogical species in chromium-based slags were studied. The chemical stability was evaluated by leaching with an acid solution. The main Cr-compounds in slags with FeSO4 and CaO/SiO2=1 were FeCr2O4 and Ca3Cr2Si3O12, while Cr3S4 predominated in slags with FeS2. The slags with CaO/SiO2=2 mainly contained CaCr2O4. The highest Cr concentration levels in the leaching liquors corresponded to slags with CaO/SiO2= 2, and the lowest Cr concentration corresponded to slags with high FeSO4 or FeS2, owing to the stable binding of chromium in the compounds FeCr2O4, Cr3S4 and FeS•Cr2O3.

Jan 1, 2011

By Ihsan Berk Tulu, Ted Klemetti, Deniz Tuncay, Cicek Sena, Zhao Haochen

"Analysis of Longwall Pillar Stability (ALPS) and Analysis of Retreat Mine Pillar Stability (ARMPS) treat the pillar as a passive structure that is designed to carry overburden dead-weight. This dead-weight is calculated by simple rules based on the geometry of the mining, such as “tributary area theory,” “pressure arch theory,” and “abutment angle theory.” Although the pressure arch loading approach indirectly accounts for the generally stiffer overburden response of narrow and deep panels, it does not include the effect of specific geology of the overburden in load calculations. The relationship between successful pillar layouts and overburden geology can be incorporated into the load calculation by using the Ground Response Curve (GRC) approach.This paper introduces the GRC modeling methodology to investigate the effect of overburden geology and excavation geometry on load transfer mechanisms using seven field measurement case studies from four U.S. mines. It was also shown that the modeling methodology used to derive GRC in this study approximates mining-induced stresses and deformations within 5% of the values measured in the field.INTRODUCTIONFrith and Reed (2017) stated that current state-of-the-art pillar design methods ignore the overburden mechanics and use estimated dead-weight of overburden to compute pillar sizes. In the United States and around the world, overburden loading is typically estimated by simple geometric rules, generally with the tributary area theory (TAT). The specific overburden mechanics, structural competence of the overburden strata, geology, in situ stresses, and overburden/pillar interactions are typically ignored. However, these important mechanical responses affect the stability of the mine pillars and openings; therefore, they also affect the safety of the mine workers.Research conducted by the National Institute for Occupational Safety and Health (NIOSH) after the Crandall Canyon mine disaster (Esterhuizen, Mark, and Murphy, 2010) showed that small panel width-to-depth ratios and stiff-strong overburden result in a reduction of the observed pillar loads, much smaller than the TAT estimate. In fact, as a response to the Crandall Canyon disaster, Mark (2010) implemented a pressure arch loading approach into the latest ARMPS program to recognize the inherently greater stability of narrow panels at depth. The pressure arch approach is a first logical step to introducing non-tributary area loading into the practical ARMPS program. Although the pressure arch loading indirectly accounts for the generally stiffer overburden response of narrow and deep panels, it does not include the effect of specific geology and mechanical response of overburden in the load calculations."

Jan 1, 2019

By James P. Kimball

Jan 1, 1881

By Edward D. Thimons

Because of the high number of accidental methane gas ignitions in metal and nonmetal mines, the Bureau of Mines searched for a simple guideline that would allow mine personnel to evaluate the methane hazard in a given mine. Air samples were collected by the Bureau in 53 metal and nonmetal mines and analyzed for trace evidence of methane gas. Samples were collected in the returns and at the working faces. Those mines classified as gassy by the Mine Safety and Health Administration had a significantly higher average methane concentration than those classified as nongassy. Of the 9 gassy mines sampled, 7 had methane concentrations above 100 ppm, whereas only 1 of the 44 nongassy mines had a concentration above 100 ppm. The 100-ppm concentration may be used as a simple and convenient guideline for forecasting the methane hazard in a mine, whether or not the mine is classified as gassy. There was no consistent correlation between commodity mined and methane concentration, nor was there a correlation between mine depth and methane concentration. Neither of these factors can be considered a guideline for predicting methane hazards.

Jan 1, 1979

By Mu Chen, Ye-Shuang Xu, Dong-Wei Hou, Shui-Long Shen, Huai-Na Wu

"This paper presents a laboratory investigation on the mechanical behaviors of the cement-clay admixture improved by polypropylene fiber. Cement can significantly improve the clay admixture. The fiber additive also improves the strength and ductility of the improved clay. The Unconfined Compression Strength (UCS) of the polypropylene fiber-reinforced cement-clay presents an overall trend to grow with the increase of fiber length. The improved clay reached its peak strength at the fiber content of 0.5%. Then the UCS of the improved clay will slowly reverse if the fiber content continues to rise. For study of curing time, improved clay behaves better in its early strength, but an inhibition will be brought about if fibers are excessive.INTRODUCTIONGround improvement technology is essential for construction of structures in soft ground. Some traditional techniques often cost much but result in little. For instance, along the coastal region of China, soft ground is often improved by backfill with high quality sandy soil transported far away, leading to high additional haulage costs and long construction period. Reutilizing the excavated soil as backfill or subgrade after treatment, by contrast, will be more economical and effective (Hufenus et al., 2006). Many researches have been conducted to improve the compression strength of soft soil, among which, the method of mixing the soft soil with cement and fly ash is one of the most common ways (Kolias et al., 2005; Horpibulsuk et al., 2009; Porcino et al., 2012). It is known that soil resists well against compression and shear force but behaves poorly in resistance to tension. Therefore, utilizing tensile elements such as fibers and strips to improve the tensile strength will be effective because of its strength isotropy, better durability and cost effective (Haeri et al., 2000; Kaniraj and Havanagi, 2001; Consoli et al., 2010)."

Jan 1, 2015

With significant increase in steel output in the world the price of iron ores has been soaring recently. Especially, there is a strong demand for iron ores in China, leading to more attentions paid to developing low grade iron ores. In this paper mineralogy of nm-of-mine hematite ore was deter-mined, and coal-based direct reduction-magnetic concentration was successfully developed to beneficiate low grade hematite ore. Mineralogy analysis indicates that this hematite ore is a super fine refractory ore, with the main valuable mineral hematite being closely associated with quartz and distributing uniformly and mostly occurring within the size of 3~5J.lITI,leading to being difficult to beneficiate due to super fine hematite and only grading 28.83% Fetotal. This hematite ore failed to be effectively upgraded by traditional processes in trial tests, such as reverse flotation, gravity concentration, and magnetic separation, or the integration of the above processes. In contrast with adoption of the coal-based direct reduction-magnetic separation process, concentrate was produced with high iron grade and metallization degree in the present work, which provides a theoretical basis for utilization of low grade iron ores. By optimization of direct reduction conditions, such as reduction temperatures, duration and mass ratio of reductant coal to iron ore, the reduced ore with 93.72% metallization degree was prepared, and then three-stage grinding-magnetic separation of the reduced ore were conducted, the final concentrate was manufactured, assaying 69.54% Fetotal and 98.01 % metallization degree, and with low content of impurities. This iron concentrate with high metallization degree produced by this process is a superior burden for converter instead of blast furnace. This process is enviromnent friendly by directly making iron using coal and iron ores instead of coke, resulting in less emissions and low production cost.

Jan 1, 2014

High flotation of iron sulfide minerals at high pH values in copper ores is mainly due to the activation of these minerals by copper species dissolved from copper sulfide minerals during grinding. Several methods have been tested to reduce this copper activation during grinding and therefore to depress iron sulfide flotation. They include grinding the minerals at high pH values or with a less reactive medium such as high chrome, and addition of a thiol collector or copper complexant during grinding. The efficacy of these methods in the flotation of a copper ore was tested against more common methods of depression of iron sulfide flotation. The mechanism of iron sulfide depression in these methods was also investigated.

Jan 1, 2014