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By Xiaoguang Zhao

The coal mining area in Northern Shaanxi, China, has been taken as the study area, and the damage mechanism of the ecological environment is discussed on the basis of analyzing the characteristics of natural eco-environment and resource development in this area. Mining subsidence is taken as an example, and by using the Gray Correlation Analysis method, the key impact factors have been selected. An assessment model with fuzzy comprehensive evaluation has been constructed, and 12 coal mines have been quantitatively assessed. This paper also constructs an ecosystem health assessment method and index system in the coal mine area on the basis of ecosystem health theory, and assesses the ecosystem health status in the Shenfu coal mining area from 2000?2006. The research results are expected to help the eco-environment protection process in the designated coal mining area.

Aug 1, 2013

By W. L. Dam

Grand Junction, Colorado’s legacy with uranium mining and milling serves as a model attracting international interest. Access to water and central location to carnotite ore containing uranium and vanadium resulted in the World War II military creating a site in Grand Junction for developing extraction techniques; subsequently, several commercial mill sites were built in the area. Uranium mills produced ore into the 1970’s as well as tonnes of radioactive waste tailings. Tailings contain radium that emits radon gas. Despite the radiation hazard, sandy tailings were added to concrete and became incorporated into roads, schools, businesses and homes. Clean up of sites containing tailings and mill sites began in the 1970’s involving city, state, and federal officials. The Climax mill site had become an auto junk yard mixed with mill tailings. A new disposal site was built out of town and away from the river in the 1990’s. After Climax mill tailings were removed to the disposal site, the land sat vacant for two decades until citizens and city officials developed a masterplan for the riverfront property. The Las Colonias river park is being built in stages including an amphitheater, gardens, businesses and parks. One of the biggest obstacles to site remediation and reuse was overcoming public outrage, fear, and lack of trust which made funding sources scarce.

Jan 1, 2020

By Iain G. Bruce

The need to improve supply reliability while improving our environmental record during the past half decade of low metal prices has required the mining industry to prioritise expenditures. Quantitative Risk Assessments using third party reviewers and specialist risk management teams have assisted in identifying hazards that can both disrupt supply and impact the receiving environment. Graphical displays using risk ellipses can simplify the presentation of the results in a Probability-Consequence (PC) graph. Development of risk acceptability envelopes using readily available financial data superimposed onto the same PC space assists management to prioritise their risks and focus on risk reduction measures. Development of this system and examples of the successful implementation of the system from several recent projects are described.

May 1, 2003

By Geir M. Haarberg

Electrochemical techniques, mainly linear sweep voltammetry and potential step chronoamperometry, were used to study the behaviour of dissolved phosphorus species in cryolite-alumina melts, The presence of AIPO4 or Na3PO4 gave rise to voltammetric current waves due to electrode reactions involving phosphorus species at potentials where dissolved alumina is stable in cryolite melts, Diffusion kinetics for dissolved P(V) species were studied, Data from industrial cells were used to determine mass balances for phosphorus, For cells being fed with secondary alumina, more phosphorus tends to end up in the produced metal, Laboratory experiments to study the effect of phosphorus in the bath on the current efficiency for aluminium were also carried out.

Jan 1, 2004

By D. R. Reeves

This paper describes the geophysical Jogging of coal that is being carried out for the National Coal Board in the United Kingdom. An explanation of the technique is given and results are presented showing estimations of seam thickness to within ±0.5 in. and ash content to accuracies of ±2.5 per cent. The basic method of interpretation is outlined and some conclusions regarding the conditions of roof and floor material which may be deduced from the logs are explained. An indication of future developments in this field, including the identification of coal type and moisture content, is given.

Jan 1, 1971

By A. Tikhonov, D. Kipper, V. Korovin, A. Olifirenko, Yu. Shestak

The present paper deals with vanadium and molybdenum sorption from industrial wastes and intermediate processing products using Cybber macroporous strong- and weak-base anionites. Vanadium and molybdenum recovery by Cybber anion-exchange resins as well as desorption processes were studied in static and dynamic modes; their efficiency was demonstrated for that purpose. The results of the work may be used to design technologies for complex processing of both ores and industrial wastes containing vanadium and molybdenum.

Jan 1, 2011

By W. H. Zieman

NORMAN WEISS, Milling Engineer, American Smelting• and Refining Company: The subject of the Forum on Rod and Ball Mill Liners is very fascinating, and there is no end of discussion when operators get together on grinding. However, the hypotheses and suppositions easily outrun the facts, especially when we •consider the inaccuracy of many reported observations. Still surprisingly small is the number of concentrators even reasonably well equipped to measure power consumption of each grinding mill, together with running time, so that data on this tangible factor, at least, can be obtained with precision. While the more elaborate devices of this nature, producing for each 24-hour period the total power consumption, average kilowatt hours per hour, short-term demand chart, instantaneous demand, and print-out, may cost in the neighbourhood of $2,500 per mill and may be difficult to justify, the combination of an ammeter, watthour meter, and running-time meter will cost only a few hundred dollars, so there appears to be little reason not to in-stall them in view of their numerous advantages.

Jan 1, 1959

By A. Galibois, H. Monette, J. L. Collins

This paper deals with the problem of caving, which occurs in varying degrees in blast holes before loading. It is shown that the distribution of the amount of caving in materials may be described by a gamma density function. A decision model to determine the optimal depth of over-drilling 'in order to minimize the expected additional cost per hole is described. Two different policies are discussed. In addition, charts which permit the mine operator to realize significant savings have been drawn for different actual situations.

Jan 1, 1971

By Tony Szwilski

Using Unity 3D as a collaborative multi-user virtual on-line environment, an interactive virtual underground mine platform (IVUMP) is being developed to provide on-line access to mine safety preparedness training with a focus on mine emergency response exercises (MEREs). Communication and information flow among MERE participants and their actions can be monitored, recorded and evaluated. A mine ventilation simulation utility VFIRE is being incorporated to enhance the realism and interactive nature of the ?in-world? exercises as well as extend its functionality to include training in real-time ventilation and fire control.

Aug 1, 2013

By D. Sanguinetti, A. Consigny, M. Nodwell

"Alkali precipitation of dissolved metals is an inexpensive but non-selective means of treating mine wastewater. Alternatively, sulphide precipitation can treat to below parts-per-million concentrations while selectively recovering valuable metals. While technically feasible, sulphide treatment of dilute waste streams increases the size and cost of the plant relative to the metals loading. Ion exchange has been applied at two separate sites to pre-concentrate nickel containing wastewater prior to recovery in smaller and more cost effective sulphide precipitation circuits. The result is a dual-circuit system that can maintain high selectivity and reduce overall facility cost while meeting strict effluent regulations.INTRODUCTIONAlkali precipitation using lime is the most common method of treating mining effluents for dissolved metals removal. This method is generally sufficient for waste streams containing mixed metals of little value, and for meeting modest metal concentration limits in the final effluent. Due to the non-selective nature of the lime process, the produced metal hydroxide sludge is of little value. All metals are removed together in a sludge product which cannot be re-processed for further value recovery.By contrast, sulphide precipitation can be used to selectively remove and recover valuable base metals (such as copper, zinc, nickel and cobalt), since the sulphide will preferentially target these metals without reacting with less valuable metals (such as iron and aluminum). The low solubility of the metal sulphide solids also supports the removal of base metals to lower concentrations than can be achieved with alkali precipitation in addition to other benefits discussed more fully in a prior paper (Bratty, Lawrence, Kratochvil & Marchant, 2006). The corollary to this solubility feature is that sulphide precipitation can function on influent streams containing low (< 10 mg/L) metals concentrations to meet very low parts-perbillion final effluent concentrations. Reagent overdosing is also minimized when compared to alkali precipitation."

Jan 1, 2012

By T. Loos

The Norddeutsche Affinerie operates an Outokumpu-Flash-Furnace as a smelting unit. The pyrometallurgical slag cleaning process is based on the slag reduction and settling in the electric furnace. Since 1972 when the slag cleaning furnace was built the throughput could be increased fourfold. However, an extensive optimisation effort is required in order to keep the copper loss low. A parameter study with a neuronal network model based on real process data was conducted to identify parameters impacting on the copper loss in the slag. It could be demonstrated that the main parameters responsible for copper loss in the final slag are fixed parameters of the flash furnace. For a better understanding of the copper loss in the electric furnace microscopic analyses of the slag structure and viscosity measurements were performed. Based on these results the reduction and settling of the copper containing droplets could be increased in both pilot plant studies and industrial scale. 4

Jan 1, 2007

By F. Chevarin

The reaction of O2 with the carbon anode is considered as the main parasitic chemical reaction affecting Hall-Heroult process anodes. The current study aims at investigating the influence of the microstructure of baked anode on its overconsumption. Samples were removed from different positions of an industrial anode. Density, porosity, Lc and BET specific surface area were measured. The anode reactivity was evaluated based on the weight losses for the samples resulting from the reaction of anode with air at 550°C after 7h. The essential parameters determined to control the air reactivity are closed porosity, Lc and pores with a pore entrance radius of 1.5, 8.5 and 12 p.m. The knowledge of effects of these parameters allows better understanding of the reactivity of anodes and consequently reduction of their overconsumption in electrolysis bath.

Jan 1, 2011

By Tomoya Kawasaki, Tatsuya Motomura, Yutaka Yasuda

Saganoseki Smelter, one of the largest copper producers in Japan, currently operates a single flash smelting furnace to produce 450,000 tons of new copper annually. The smelter used to employ two flash furnaces, and integrated the two into one in 1996. Since then, various improvements to its facilities and technologies have been made to increase productivity. To upgrade the operation efficiency, "stability" was considered a key issue, and the measures were taken to increase the operation and facility reliability. Currently, the furnace is running at a feed rate of 215 DMT/h, while the furnace utilization has been maintained at 97%. This paper outlines recent improvements that have made to increase furnace productivity and efficiency.

Jan 1, 2014

By K. E. Waters, M. Mirnezami, R. Gauvin, A. Jordens, K. W. Malas

"There is currently very little information on the physico-chemical properties of rare earth elementbearing minerals, or on their processing. With the increasing demand for rare earths, this is something that needs to be addressed. This paper introduces some surface chemistry analysis of fergusonite (YNbO4), and the bubble-particle attachment. Zeta potential measurements indicate adsorption of sodium oleate and, to a lesser degree, potassium amyl xanthate onto the surface, and an increase in attachment to an air bubble is observed at pH 4.5 and 6.5. At a pH of 10.5, no attachment is observed, whether in the presence of the reagents or not. This analysis, although initial, will be used to initiate flotation tests, in order to facilitate the selective recovery of fergusonite. INTRODUCTIONRare earth elements (REE) are increasingly in demand, due to their prevalence in both renewable energy devices and high-end electronics. An article in the New Scientist highlighted the importance of a number of REE, many of which most people are be unlikely to have heard mentioned (Crow, 2011). From batteries (lanthanum and cerium) to magnets (dysprosium and neodymium) and lighting (yttrium), the REE are crucial to the advancement of technology and energy saving devices. For example, neodymium is finding most use in the high end magnets that keep the motors turning that power wind turbines and electric cars. In the case of yttrium, the demand outstripped the supply in 2010, emphasising the need to develop deposits containing this and other REE (Crow, 2011). The impact of our dependency on REE has become even more apparent with the reduction in exports by China, which currently controls 97 % of the world’s rare earth production (Pitts, 2011).With the increasing demand for rare earth elements (REE), there is a drive to exploit the known resources around the world. However, the physical beneficiation of the rare earth element bearing minerals is a subject which will require a great deal of investigation to fill the knowledge gaps surrounding these developing rare earth projects. There are numerous articles on REE mineralogy as well as the hydrometallurgical processing of REE concentrates (Alex, Suri, & Gupta, 1998; Peter Gromet & Silver, 1983; Ring et al., 1993; Schnetzler & Philpotts, 1970; Uda, 2000), however a common feature amongst these resources is the lack of detailed descriptions of the physical beneficiation processes required to concentrate REE-bearing minerals. There is work being conducted into reagents and methods for use in recovering some rare earths from their associated ores (Bulatovic, 2010; Ni, Parrent, Cao, & Liu, 2011), but much more in-depth research is required."

Jan 1, 2012

By J. I. Gazzarri

A model of solid oxide fuel cell AC impedance behaviour has been developed and is used to simulate the frequency response of a single cell with and without mechanical damage. The results indicate that the presence of mechanically induced damage within the components of a solid oxide fuel cell can be detected by comparing the frequency response of the undamaged cell with that of a cell in which in-plane cracking or delamination has occurred. The presence of such defects manifests itself as a new semicircle in the Nyquist impedance diagram of the full cell. A parametric study reveals the resolution capabilities of the method in terms of the geometrical characteristics of the defects.

Jan 1, 2005

By SANDVIK WHITE

The mining industry produces approximately 4-7% of global greenhouse gas (GHG) emissions. It is fundamental for mining operations to take immediate sustainable action to actively contribute to an emissions-free future for the next generations. The mining industry has traditionally relied heavily on diesel technology and transitioning to more sustainable solutions requires change management to drive cultural acceptance and new product development. Sandvik was interested to find out the lifetime emissions of a single drill rig and to compare similar application diesel and BEV drill rigs with same use profile to each other. That led the calculation and pondering towards comparing different countries and mine sites as well

Jan 1, 2023

By K. Östcrdahl

We are developing a cost-saving and environmentally friendly process with low energy consumption to recover the metal content and recycle the acid from spent pickle baths. The metals are precipitated as metal fluorides, which can be turned into metal oxides and hydrofluoric acid by thermal hydrolysis. In the proposed process the solution is concentrated by nanofiltration and the metals are precipitated in a subsequent crystallization step. Different nanofiltration membranes have been evaluated in experimental batch tests. The membrane MPF-34 from Koch Membrane Systems offered both good flux and acceptable metal retention even after long periods of acid storage. The solubility of B-FeF3.3H20 has been measured at varying acid concentrations and at different temperatures. The solubility decreases with increasing hydrofluoric acid and nitric acid concentrations. This suggests that the crystallization process should be operated at high acid concentrations. The crystal growth rate of B-FeF3.3H2O is found to be quite low but increases significantly with temperature. This suggests that the crystallization process should be operated at higher temperatures (40 - 60°C). Within the project a pilot plant has been constructed where the spent pickle bath solution is concentrated by nanofiltration to the desired metal fluoride supersaturation, and B-FeF3.3H2O is crystallized in a 10 L continuous crystallizer.

Jan 1, 2006

By Tibor Horvath

Dust abatement is possible on bulk materials, whether conveyed or stockpiled. Minimum (ppm) quantities of chemical additives can efficiently and rapidly control dust of conveyed substrates with no effect on floatation chemistry. Top coating of large surface areas can control surface dust and wind erosion. Environmental and toxicity impact must be considered in any treatment, especially on areas with percolation runoff, leachates, or limited containment. The most effective dust control is preventing release of substrate fines rather than trapping and removing air borne dust. Techniques to prevent release of fines from conveyed substrates will be discussed. Dust control dynamics are a very complex combination of solid phase physical and chemical interactions between the substrate and the fines. ?Smart Technology? products permit dust abatement of stockpiled substrates and tailing fields with no environmental impact. Using ?Smart Technology?, the dust abatement products remain active and can re-seal damaged areas. Efficient, low environmental and toxicity impact, dust control will be demonstrated through case studies where these principals have been applied.

Oct 1, 2010

By R. Salimi

Tricalcium aluminate hexahydrate (TCA) is used as filter-aid for security filtration in the Bayer alumina process. TCA is typically produced on-site by mixing Bayer liquor with slaked lime. Specific properties are required from the TCA to ensure adequate filter throughput, lifetime and importantly effective reduction of solid/colloidal impurities from the solution. The effect of reaction time on morphology and particle size distribution of tricalcium aluminate was studied for a batch experiment at simulated process conditions. It was found that reaction time plays a critical role on the morphology, crystal structure (diameter and crystallinity) and particle size distribution. In the early stages of the reaction, nucleation dominates the crystallization process followed by growth dominated by agglomeration up to a mean particle size of 10 µm. The particle morphology shifted from an irregular shape to more spherical throughout the course of the reaction.

Jan 1, 2014

By G. M. Castillo

Newmont?s Phoenix mine started production in March of 2006. Due to the extreme hardness of the ore, the mill has struggled to meet throughput projections. Grinding studies showed that optimizing the existing circuit would not achieve budgeted throughput. These studies also showed that the pebble crusher was being underutilized due to the inability of the SAG mill to break the rock. The concept was developed to supplement the feed to the existing pebble crusher with a secondary crusher. Models of this process looked favorable so a portable crusher was installed to test the process. The temporary crusher was successful at increasing the throughput by 7% and based on the operating data, plans are currently being developed to install a permanent secondary crushing system in front of the SAG mill. This paper will review the results from the test crusher and the flow sheet for the permanent secondary crusher.

Jan 1, 2012