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By Panshi Xie, Yan Chen, Shaogang Wu, Yang Hang

In order to realize the intelligent mining of coal seam with large dip Angle, this paper adopts the methods of large proportion variable Angle loading threedimensional physical simulation experiment, numerical simulation and field measurement with digital twin technology. The hydraulic support with large dip Angle and large mining height is used as the prototype to design the physical entity model of 1:5 hydraulic support, combined with modeling and graphics rendering technology. Angle, displacement and load sensors were selected and placed to realize the data channel between the lower machine and the upper computer of the digital twin system, so that the position and load data of the physical entity model and the twin model of the laboratory hydraulic support could be shared in real time. Moreover, the multi-dimensional dynamic and static load transfer law and the position evolution characteristics of the support and surrounding rock under different inclination angles were analyzed. The results show that: with the increase of the Angle of the working face, first, the initial support force required by the support decreases, and the damage degree of the roof increases; When the roof is soft, the lifting operation can avoid the instability of the support to a certain extent. Second, under the action of positive pressure, the load of the top beam under different angles is balanced; Under the backpushing action, the load in the upper inclined area of the shield beam increases gradually, while the load in the lower inclined area decreases gradually. Under the lateral push, the load changes periodically, and the load in each cycle is increased compared with that in the previous cycle. Third, the numerical simulation analysis shows that the load on the lower bracket is less than that on the upper bracket, and the load on the bottom of all the columns is greater than that on the middle and upper brackets. In order to reduce the impact of the columns on the bottom plate or the base, it is necessary to improve the anti-subsidence ability of the base. Finally, according to the research results, the improvement and optimization measures of the support are put forward, and the field test shows that these measures effectively solve the problems of sinking, sliding and tipping of the support in the working face with large inclination Angle, and obtain good application results.

Feb 1, 2024

By Meng Li, Hao Nie, Weitian Ding, Mamdouh Omran, Ying Li, Yao Ge, Yaowei Yu, Abourehab Hammam, Lei Zan

This study examines the isothermal and non-isothermal reduction behaviors of iron ore compacts in a pure hydrogen atmosphere and compares the results obtained during the reduction process by CO. The different phases accompanying the reduction reactions were identified using X-ray diffraction (XRD) and its morphology was microscopically examined. In isothermal experiments, temperature plays a significant role in the reduction process. At any given temperature, the reduction rate during the initial stages is higher than that during the final stages. The reduction rate in H2 atmosphere was faster than in CO gas. The comparison of activation energy values suggested that reduction with H2 is more efficient thanwith CO. At the same temperature, the time required to achieve a certain degree of reduction was lower when using H2 gas than CO atmosphere. In non-isothermal tests, the heating rate has a significant effect on the reduction rate and reduction extent. At the same heating rate, the degree of reduction was higher in H2 atmosphere than in CO gas. Based on experimental data, the parameters of reaction kinetics were deduced by application of model-free and model-fitting methods. The reduction in H2 atmosphere was controlled by nucleation model (Avrami-Erofeev model), while the CO reduction reaction was controlled by gas diffusion.

Sep 29, 2020

By Frank J. Skudrzyk, Vladimir F. Petrov

In compliance with the current Russian environmental legis­lation, possible impact of industrial activities on the environment is restricted by acceptable limiting values (maximal allowable concentrations - MAC) of individual chemical substances in the natural environment - water, atmospheric air and soils. These norms have federal status and are valid for the whole territory of Russia. Disposal of the substances, for which no MAC is estab­lished, is forbidden by the law. Many gold mining companies use cyanide in precious metal recovery. This paper overviews the Russian experience in pro­tection of natural water reservoirs from technogenic impact of cyanic technologies. Major toxic compounds, contained in liquid and solid rejects from hydrometallurgical treatment of gold ore using cyanidation, are cyanides (CN), thiocyanates (SCN) and cyanide metal com­plexes. Unlike western classification of various cyanide types, in Russia any inorganic cyanide compounds (simple and in com­plexes with metals), with the exception of iron cyanide com­plexes, are considered toxic and the acceptable limiting value is established for them. MAC is 0.05 mg/I for fish reservoirs and 0.1 mg/I for drinking water. For iron cyanide complexes MAC is 0.15 mg/I for fish reservoirs and 0.25 mg/I for drinking water. Russian norms for thiocyanates are practically as rigid - the acceptable limiting value for them in fish reservoirs is at the level of 0.07mg/l (0.15 mg/I for potassium thiocyanate) and for drinking water - O. lmg/1. Norms for metals are established on the basis of total content regardless of the form in which they are present in water - as cations or complex ions. It should be noted, that in case several toxic compounds of the same limiting value (for cyanides, thiocyanates and base metals the limiting value is toxicological) are present in water. Their allowable concentra­tion is calculated as the sum of actual concentration of each com­pound, divided by the corresponding acceptable limiting value, with the result not to exceed one (compounding effect). Differences in cyanide classification and the necessity to include thiocyanates dictate different analytical methods. This, in a number of cases, results in certain discrepancies in analytical results. Until recently chlorination was used as a basic process of detox­ification of wastewaters. Calcium hypochlorite powder or hypochlorite pulp, prepared of lime milk and chlorine shipped to the plant, were used as a reagent. Chlorination is an efficient method: it allows to completely destroy plain and complex cyanide, in addition to iron complexes, and thiocyanates. A good example of high efficiency chlorination can be found at the Mnogovershinniy mill near the Okhotsk Sea located in the salmon spawning area, for which we designed an automated chlorination plant for tailings dam. Since plant start-up ten years ago, the required concentrations of cyanides and thiocyanates have been kept at the MAC level required by environmental regulatory agen­cies and no harmful affects on ichthyofauna has been reported. One major drawback of chlorination is high cost of the major reagent, as well as secondary contamination of detoxified waters by chlorides. Secondary contamination by chlorides becomes obvious in the course of detoxification of wastewaters of com­plex composition, which require increased reagent consumption. Recent changes in economic conditions in Russia caused the necessity to direct efforts to reduce the costs of precious metals recovery, and in particular, wastewater treatment. We have con­ducted certain work in this direction and obtained positive results. We hope that our experience described below will be of interest to other specialists particularly taking into account the current low gold prices.

Jan 1, 1998

By Alexander Sutulov

1. INTRODUCTION According to the classical economic approach of the open market economy, copper supply should be regulated by market forces which are (a) demand and (b) prices. In fact, demand is of primordial importance because prices are a reflection of supply-demand balance: they go up in times of shortages of supply and down when over-supply situation exists. In the past few years, this basic mechanism of market economy has been under pressure from a number of non-market forces, such as social and monetary problems of sane important copper producing countries; structural changes in copper mining companies through mergers with oil companies; and other factors which greatly contributed to distortion of the basic supply-¬demand equation. As a result, we have faced in the last three years a situation of oversupply rarely seen in the past, with a catastrophic fall in copper prices, huge losses at mines and unprecedented indebtedness of copper producers. This has deep repercussions in the copper business and its future supply outlook. This is particularly so when taking into consideration that high indebtedness and high interest rates conspire against the very survival of some traditional producers. As we write this comment (July of 1985), close to one half of U.S. copper production capacity is closed down, sane of it for good, while the same precarious situation exists in Canada, Australia, Zambia, and some other primary producers who cannot face present low prices with equally low costs. The question is then what this situation means for the medium-¬term future, until the end of this decade, Particularly when taking into consideration the fact that some of the factors influencing it are of a long-term character. 2. SUPPLY-DEMAND SITUATION IN THE LAST FIVE YEARS Since the last boon year, in 1979, when world copper consumption reached a record of 9.8 million metric tons of refined copper, demand dropped to only 9.0 million tons in 1982, when the crisis bottomed out, and then steadily recovered to the level of 9.7 million tons in 1984. Meanwhile, copper production, which in 1979 was only 9.4 million tons, in spite of the fall in demand, grew to 9.7 million tons in 1981 and 1983 and only temporarily was cut to 9.4 million tons in 1982 and to 9.5 million tons in 1984. As a result of this imbalance, hugh copper stocks were accumulated with supply systematically out¬growing demand by over 2 million tons at one time. With the Western World refined copper demand running at an average of 115,000 tons per week, this oversupply was equivalent to between 15 and 18 weeks production, i.e. twice as large as normal. This was immediately reflected in very low copper prices. Another contributing factor to relatively low copper prices was the lack of speculator interest for this commodity. Between 1981 and 1984 the world experienced a very intensive period of wealth distribution, high interest rates and intensive restructuring off world economy and its industrial sector. Therefore, much of the available money was attracted to more lucrative and attractive investments rather than to the lack-luster performance of copper, and for that matter, of the metal sector in general. The much announced and discussed recovery of the U.S. economy since 1983, and particularly in 1984, with an overall growth of the GNP by 6.8% in 1984, happened to be more oriented to the service sector than the industrial sector and therefore this recovery was not adequately reflected in copper consumption nor to metals in general. This put serious doubts about the future demand for copper. Consequently copper prices failed to improve in spite of an apparent fall in stocks and a healthy increase in the demand for copper since 1982. At the time of this writing (July, 1985), although same analysts claim that the available stocks are running at about 8 weeks of supply, which are considered to be below normal, copper prices are still very low at between 65 and 67 cents per pound of copper. Part of the answer may be the normal seasonal slow-down period in the Northern Hemisphere due to summer vacations and

Jan 1, 1986

By C. Bazin

The fundamental error associated to the sampling of heterogeneous ore particles is unavoidable and can only be minimized by an adequate selection of the sample mass and/or size reduction of the sample before division into sub samples for testing or assaying. The preparation of ore batches to carry out the mineral processing evaluation of an ore is a sampling process. The fundamental error associated with the division of the ore into batches is responsible for the differences in the composition of the batches. This paper attempts by various means to assess the reproducibility of the gold content of test batches prepared from a gold ore sample. The results of the investigation shows that for fine gold grain sizes the variability in the composition of the batches is less than that predicted by Gy?s formula and that the gold grain size is a strategic information in the assessment of the gold content variability of test batches.

Feb 23, 2014

By Peter Zhang, I. BERK TULU, Morgan M. Sears, Heather Dougherty, Ted Klemetti, DYKE MARK VAN, Gabriel S. Esterhuizen

Ground falls in longwall gateroad entries remain a concern in modern longwall operations. The gateroads are subject to changing horizontal and vertical ground stress induced by longwall extraction. These stress changes can result in failure of the strata around an entry leading to large deformations of the entry roof, floor and ribs. The gateroad support systems are required to control the failed strata while maintaining safe access to the longwall face and unimpeded ventilation. This paper presents research conducted to better understand the stability issues in gateroad excavations and to develop procedures for evaluating support and layout alternatives for longwall gateroads. Using the results of a field-monitoring program and numerical model analysis of case histories, a conceptual model of gateroad support needs was developed. The conceptual model formed the basis for developing a set of equations that can be used to estimate likely roof sag and support loading for given roof geology and longwall-induced loading conditions. The developed equations were used to compare predicted gateroad stability to field study results, showing satisfactory agreement. The calculation procedures are used to demonstrate their application in assessing support alternatives at a case study mine. It is concluded that the developed analysis procedures provide realistic assessments of likely ground stability and can be used to evaluate alternative gateroad support systems at operating longwall mines.

By C. Ford, R. E. Salas Rojas, J. P. Contreras Rodriquez, S. A. Pierce

Heightened environmental consciousness has resulted in the development of various international accords dealing with natural resource management. This international awareness is now being translated into regional and local initiatives that proactively implement collaborative environmental management programs. One such program was recently initiated in northern Chile in recognition of the interconnection of Andean salars. Cooperative efforts between industry, governmental agencies and academic professionals have resulted in the implementation of simultaneous environmental monitoring of flora and fauna in the salars of northern Chile. This coordinated effort is leading to an improved understanding of the migratory patterns of South American fauna, as well as improved access to an expanded database for the multiple user groups associated with the Andean salars. The El Abra Mine is actively participating in these coordinated monitoring efforts.

Jan 1, 1999

By Earl L. Rau

At the present time, whether an electric utility uses high-sulfur coal is largely determined by geographical location, clean air legislation, and the age of the power plant. Acid rain legislation may well be the new force to change the use of high-sulfur coal. A number of coal papers were presented at the SME Fall Meeting in St. Louis, MO, Sept. 1986. These papers discussed high-sulfur coal in relation to its economics, trends and prospects, value of cleaned coal, and coal-cleaning technology. The Clean Air Act of 1970 required the reduction of SO, emissions from most stationary electric-generating plant to 0.5 kg (1.2 lbs) SO2, per million Btu of heat input. It was possible for many plants to utilize lower-sulfur coal or a mixture of high-sulfur and low-sulfur coal to meet this emission requirement. This 1970 act greatly increased the use of low-sulfur western coal. The 1978 amendment to the Clean Air Act required all new plants to use Flue Gas Desulfurization (FGD) to meet a requirement of 70% reduction of potential SO2 emissions to 0.3 kg (0.6 lb) SO2 per million Btu of heat input. With the requirement to use FGD, there was little or no demand for low-sulfur western coal in new eastern power plants. If' new acid rain legislation is enacted, it likely will require sizeable reductions in SO2, emissions by existing coal users. There might then be a shift to greater use of low-sulfur coals. The low-sulfur coals could come from either western or eastern mines or from cleaned eastern coals. Economics will dictate the approach older power plants will take to meet new regulationsuse FGD or low-sulfur coal. Coal use for electric power generation has changed from 1970 to 1985. Table 1, (Land, preprint 86-333) shows the change. The table shows that in 1985, US utilities used about 255 Mt (280 million st) of high-sulfur coal. Some 45 to 54 Mt (50 to 60 million st) of high-sulfur coal is being used in plants equipped with FGD and most of this use is in eastern states. This leaves 200 to 209 Mt/a (220 to 230 million st) of high-sulfur coal being used without FGD treatment. These plants are at risk if acid rain legislation is passed. Most of these plants are in the east and are more difficult to supply with low-sulfur coal. Estimates range from $20 to $30 billion capital investment and from $5 to $9 billion dollars per year operating costs to reduce SO2, emissions from those old medium-to-high-sulfur coal-burning plants. G. W. Land, (preprint 86-333), also presents tables relating to power generating costs and coal types. The author's tables are extracted from Land's tables IV and V. Table 2 here presents costs for a new plant. This includes the impact of different heat rates, fuel costs, fuel qualities, operating and maintenance costs, labor costs, and waste disposal costs. Table 3 compares estimated costs to retrofit an older plant with a limestone scrubber versus switching the same plant to low-sulfur eastern or western coal. Costs of switching include upgrading the electrostatic precipitator and - with western coal - costs of derating. Bhagwat, (preprint 86-325), details the trends in high-sulfur coal markets from 1974 to 1984. He also gives some prospects for high-sulfur coal markets, 1984 to 1994. The prospect depends mostly on whether acid rain legislation is enacted. By 1994, if New Source Performance Standards (NSPS) continue to be applied, high-sulfur coal demand from six mid-west and eastern states is expected to increase by 27 Mt (30 million st). • L. A. Khan and J. W. Baxter, (preprint 86-373), discuss several coal cleaning technologies such as froth flotation of fines, bulk oil separation and oil agglomeration, oil agglomeration/flotation, and air-floc flotation. ? (Space limitations preclude listing references. A complete list is available from the author.)

Jan 1, 1987

By Peter Zhang, Daniel Su, Mark Alexander Van Dyke, Heather Dougherty, Bo Hyun Kim

The National Institute for Occupational Safety and Health (NIOSH) has been evaluating longwall mining-induced strata fractures and their impacts on casing stability of Marcellus shale gas wells located in longwall pillars. To understand the extent of overburden fractures after longwall mining, NIOSH researchers drilled a post-mining corehole into the fractured strata above the Pittsburgh coal seam longwall gob. Knowing the extent of the fracture zone height will help gas operators minimize the hazards of drilling into longwall gobs. The core was retrieved from the surface down to the top of the gob void. Various fractures were encountered varying from 35 to 64°, depending on lithologic type and relative closeness to the gob. The longwall panel dimension was 457-m wide and 3657-m long, in which the total fracture zone height was found to be at 141 m and the hydraulic connected fracture zone at 87.7 m above the top of the Pittsburgh seam. In addition to core drilling through the gob, FLAC3D modeling was also used to simulate the formation of fracture zone and the orientations of longwall-induced fractures. This study provides much-needed evidence on the fracture zone of Pittsburgh seam longwall gobs to help gas operators avoid potential hazards associated with drilling through highly fractured zones in longwall gobs.

Jun 9, 2022

By G. Deschênes

In Part I of the work, gold and silver were shown to be efficiently extracted from Kupol samples using lead nitrate in a cyanide leach system. In Part II, a comparison of the technical and economic merits of a new technology called CELP (CANMET Enhanced Leaching Process) was made with the cyanidation/AVR(Acidification-Volatilization-Recycling) process using 8 metallurgical variability samples as well as a large composite sample which represented initial two years of Kupol mill feed. The composite sample had 33.4 g/t Au and 289 g/t Ag. The metallurgical demonstrated that the CELP produced very similar gold and silver leach extractions compared to the standard Cyanidation /AVR leach conditions at 1/2 the cyanide concentration (1000 ppm NaCN in CELP vs. 2000 ppm for cyanidation/AVR leach conditions). It was estimated that the total cost per ton, were approximately the same for the two technologies (total cost of the CELP with the use of Merrill-Crowe at $46.48/ton, with cyanidation/AVR at $46.13/ton). However, the implementation of the CELP would eliminate a capital expenditure of approximately $5 million. Eight variability samples used to confirm the previous results showed that on average the gold and silver leach extractions with the CELP and the feasibility leach conditions were very similar for gold extractions, but 4.6% higher for silver extractions compared to the conventional cyanidation. The decision was made to remove AVR cyanide recovery from the Kupol flowsheet and implement the CELP at Kupol. The ability to use conventional leach equipment with the CELP and simplify the flowsheet was also a factor, given the remote location of the Kupol Mine.

Jan 1, 2009

By John Newby, Mahmood Khwaja, Bernard Theron, Janice McGovern, Bernard Catalano, Michael S. Schultz

Launching a full-size pressurized-face Tunnel Boring Machine (TBM) in difficult ground conditions is always challenging. Recently, few projects have innovated the process by scaling the trenchless method of pipe jacking, and modified steel bell approach, to facilitate the launching of a full-size TBM without the need for large and deep trenches, starter/tail tunnels, or for incrementally installing supporting gear as the machine advances. This paper presents three such projects; evaluates the post-bid contractor proposed modifications; details the innovative use of pre-cast pipe segments to facilitate machine launch; and, provides an overall assessment of the benefits, challenges and lessons learned related to the modified approach.

Jun 13, 2021

By Luis Yacher

CONTAC Engineers is a Chilean based company which works on process control and automation, principally for the minning industry. Jointly with other local and international engineering firms, CONTAC has participated in most of the last expansion and modernization plans being carried out at the Chilean pinning industry. At presente, CONTAC is involved on a research and development plan for the design and implementation of new instrument and process control procedures for mineral process automation. One of these efforts is the design of an ore size analyzer for coarse ore being transported over a conveyor belt. A feasibility and prototype study was made at a SAG Mill Plant and currently a high resolution, high speed analyzer is being developed. It will became available on early 1986.

Jan 1, 1986

By David A. Newman

The Geomechanics Classification (Bieniawski, 1979) was modified for entry and roof support design in underground room-and-pillar coal mines. Adjustment multipliers were introduced to incorporate the influence of strata weatherability, high horizontal stresses, and the roof support reinforcement factor into the existing classification system. Sixty-two case histories of both standing and fallen mine roof were collected from two mines in the northern Appalachian coalfield. Twenty-seven engineering and geologic parameters were recorded for each case. A partial correlation analysis was carried out on the cases to establish which parameters have a significant impact upon the supported stand-up time of coal mine roof. Survival analysis, a statistical technique used in medical research to assess the effect of a drug or treatment on a patient's life expectancy, was conducted together with stepwise multiple regression to derive values for the adjustment multipliers. A practical example is included to illustrate the application of the modified Geomechanics Classification to underground coal mine design.

Jan 1, 1985

"The profile of the respondents was that of a professional responsible for communications, community relations or corporate social responsibility programs. By targeting a consistent professional profile it was possible to ensure that most respondents had a similar degree of responsibility and/or decision-making ability related to the application of communication technologies. The research attempted to be inclusive and attention was paid to interview respondents from both genders and from indigenous groups.4, 5 A codebook of 80 themes was developed that highlighted recurring topics; for example, codes were created to identify risks, benefits, policies and learning process of using social media and included topics that were repeatedly emphasized by respondents (i.e. age, efficiency and language). Both manifest coding (i.e. coding of the visible content, such as specific words) and latent coding (i.e. coding of underlying meanings) was undertaken (Creswell [13]). The codes were used in the qualitative analysis using ATLAS.ti software and network views were created to illustrate the relationship between major themes of this research. There are limitations to this research, largely related to the changing nature of the Internet and communication technologies. There is also a geographic limitation to the application of this research because most of the data was gathered primarily from Canadian sources.6 Different levels of Internet penetration, or limited access to computers or mobile devices, and low literacy rates may reduce the applicability of the research in countries with low Internet penetration. A more systematic process to selecting candidates may have helped bring balance to the final list of interview respondents. For example, most of the corporate respondents were from medium and large companies and there was not adequate representation of small mineral exploration companies. The research did not probe into social media applications by different business groups within the mining sector, such as smelting and processing."

Jan 1, 2011

By Young C. Kim

Introduction and Objective of This Paper Computerized open pit mine models* are more and more used today for feasi¬bility studies as well as for long range mine planning. In fact, using these models is becoming an enforced practice due to various reasons. One main reason is its capacity to evaluate several designs in a fraction of time required by manual effort. Another reason is the necessity to evaluate several. pit designs due to ever decreasing grade of the orebody and increasing financial risk due to smaller profitability margin. In spite of today's accepted use of computer models, very little guidelines are available which the average practitioner can follow either to choose or to build the type of model best suited for his need. Consequently, the objectives of this paper are: 1. To review the current state of the art in the computerized open pit mine models. 2. To provide some suggestions for model selection. 3. To share our experiences in developing a model for a highly irregular copper ore deposit (see Appendix).

Jan 1, 1977

By Dermot M. Ross-Brown

The objectives of this generic study were to use numerical modeling techniques to determine under what conditions seismic waves generated by an earthquake might cause instability to an underground opening, or cause fracturing and joint movement that would lead to an increase in the permeability of the rock mass. In general, the study showed that moderate earthquakes (up to 0.41 g) did not cause instability of the tunnel or major fracturing of the rock mass. An artificial rock-burst tremor with high accelerations, however, was found to be amplified around the tunnel, and fracturing occurred as a result of the seismic loading in salt and granite. In shale, even moderate seismic loading resulted in tunnel collapse.

Jan 1, 1981

By Jim Huerta

Diesel fuel usage in the mining industry continues to escalate. This is because approximately 60 percent of all mined materials are surface extracted by large equipment using diesel fuel, which continues to increase in cost per gallon. For example, coal mining uses large equipment such as wheel loaders, wheel dozers, draglines and [ ] dredgers. In one year, three of the largest U.S. coal mining operations consumed approximately 567 million to 852 million L (150 million to 225 million gal) of diesel. At an approximate cost average of $3.25/gal the expenditure on diesel is $487 million to $731 million per year. So, are there any solutions that could reduce this cost burden? Yes, there are. Coal mining companies can extract less ore; use more efficient extracting equipment that consumes less fuel; wait for a significant reduction in the cost of fuel; or find and use technology that would create efficiencies that would lower the cost. Nanotechnology is one such technology that might provide the means to create the efficiencies that will significantly lower diesel fuel costs.

Jan 1, 2011

By Ari Jokilaakso, Junjie Shi, Zhuo Chen, Pekka Taskinen, Xiang Gao

The amount of copper flash smelting slag has increased during the recent years along with an increasing slag-to-metal ratio. During slag tapping, some copper sulfide is mechanically entrained. As a result, it is necessary to recover copper matte from the slag by suitable methods. At present, the most common way is slow, controlled cooling in a transfer ladle. However, research on the detailed effects of slow cooling and the function of slag modification is rare. This paper described experiments that were performed at different cooling rates (0.5, 1.5, 3, and 7 °C/min), with and without additive. A detailed characterization of the copper-rich phase and its particle size was subsequentlymade using SEM-EDSmicrographs and image analysis software.With a decrease in cooling rate, the particle size of the copper-rich matte phase became larger. The addition of gypsum and carbon as a slag modifier affected the size of the copper-rich phase slightly, and its chemical composition was modified compared with the experiments without additive.

Jul 31, 2020

By J. Gibson

"INTRODUCTION As one of the most pressing and important political debates of this century, climate change has captured global attention and is forcing governments to take action towards decreasing GHG and carbon emission levels below what was previously thought to be necessary. With the ever-increasing price of diesel fuel accompanied by the popular topic of carbon taxes and greenhouse gas emissions, the mining industry is looking to industry specialists for assistance. The benefits of a no-idle policy reach far beyond carbon reduction and fuel savings, ranging from decreased maintenance to increased engine life. With products like battery powered A/C systems and diesel-fired heaters, going no-idle is easier today than ever before. With both systems being manufactured to withstand the harsh environments of the mining industry, the end user will see a seamless change from conventional, inefficient belt-driven systems to future, stand-alone mobile equipment HVAC. THE HISTORY OF GHGS AND CLIMATE CHANGE In 1896 Svante Arrhenius first claimed that the combustion of fossil fuels may eventually result in enhanced global warming, but not until 1955 did Gilbert Plass draw global attention to global warming by summarizing that adding carbon dioxide to the atmosphere would intercept infrared radiation and thus warm the earth. Then in the early 1960’s Charles Keeling developed modern technology to produce concentration curves for atmospheric CO2 (Figure 1). In 1988 the Intergovernmental Panel on Climate Change (IPCC) was founded by the United Nations after acknowledgement of a rising global annual temperature. The IPCC consists of over 2500 scientific and technical experts from more than 60 countries, and because climate change could not be solved by a single country, the Kyoto Protocol was negotiated in 1998 requiring all participating countries to reduce their GHG emissions by at least 5% from the 1990 levels. The Protocol was signed by 186 countries in 2001 (since then several countries have retreated from the agreement, including the United States)."

Jan 1, 2015

By J. S. Bays

Industries are challenged to meet increasingly stringent regulations for selenium and metals. Cost-effective treatment is required to minimize the economic impact of environmental compliance. Low-cost biological treatment of selenium can be achieved passively using biochemical reactor cells composed of natural organic media components such as wood chips, sawdust, hay, composted manure, and peat. The reactor cells create an anaerobic microenvironment for biological reduction and sequestration of selenium and other metals. Biochemical reactors can be combined with constructed wetlands for flow equalization and to remove the organic byproducts in reactor cell outflow. Passive treatment reduces capital cost and operational effort compared to more expensive and complex physical and chemical treatment. Recent pilot and full-scale projects by mining companies and by the US Bureau of Reclamation demonstrate that passive treatment can achieve compliance with selenium concentrations over a range of flows and environmental conditions. Case histories of passive selenium treatment systems and their key findings are provided, and prospects for future applications are summarized.

Feb 27, 2013