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By S. K. Kawatra, H. L. Dilley, W. W. Wen, T. C. Eisele

To improve the sulfur-rejection capability of a coal-cleaning plant, it is first necessary to evaluate the performance of the existing circuit. This information can then be used to decide whether there would be significant benefits from improving the operation and control of the existing circuit, or whether further improvements would require more radical process changes. This paper describes a simple model for evaluating heavy-media separation circuits, and presents a case-study of such an analysis of an operating heavy-media coal cleaning plant. Efficiency curves were calculated and modelled using Lynch's method, and a simplified expression was derived for calculating the Ecart Probability value from the model parameters.

Jan 1, 1995

By H. H. Murray

New and improved beneficiation techniques are available to allow the production of clay minerals of exceptionally high purity. This is particularly true for kaolins and smectites. Wet processing techniques include particle size separation, high intensity magnetic separation, chemical leaching ,flotation, and selective flocculation. The blending of clay minerals with other minerals provides opportunities to make special ceramic materials such as cordierite and other minerals that have very special ceramic properties including low heat expansion, high fired strength, low absorption, and other desired qualities.

Jan 1, 1990

By Mostafa Benzaazoua, Mariam El Adnani, My Ahmed Boumehdi, Rachid Hakkou, Salah Ouhamdouch, Abdelmalek Goumih

This study focuses on the environmental characterization and assessment of long-term neutral mine drainage (CND) potential from waste rock piles at the abandoned Erdouz mine in Morocco. The study involved metallographic analysis, static tests, and column tests. Results indicate that the waste rock is not an acid mine drainage generator but produces CND, mainly with sulfates exceeding Moroccan standards. The waste rock is relatively stable and could be reused after pretreatment.

Jan 25, 2022

By C. E. Jordan

The Bureau of Mines conducted research to measure the improvement provided by fine bubbles on the flotation of fine-sized particles (minus 20-um size) in an effort to improve flotation efficiency in our domestic minerals industry. The turbulent velocity distributions of the fluid within the flotation cell were measured as a function of time and position and used to increase the precision of a fine particle, turbulent flotation model. For the mineral system investigated, improved flotation response was obtained under laboratory conditions by using small bubbles and intense agitation. These results matched the model's predicted response.

Jan 1, 1989

By S. Bahrampour

One of the basic requirements for designing an optimized rock support for an underground opening is having reasonably enough geological information. It is often financially impractical to obtain detailed geological information about the rock surrounding the excavations. The geological and geotechnical information which are obtained during the construction phase are also usually inadequate and need periodic operation stoppage. Penn State University- J.H. Fletcher & Co. joint venture is to improve the existing instrumented roofbolter so that the 3D geological and geotechnical map of the rock mass surrounding the underground working can be generated real-time as the data is being collected. This information will also be used to design appropriate support for different sections of mines. In this paper, recent results in improving the performance of the measurement while drilling system will be discussed. Moreover, updates related to borehole probing methods for estimating the properties of the rock masses will be presented.

Feb 23, 2014

By Roger Bell

Most modern mines can profit from improvements in information handling. Recording systems in many cases were designed to satisfy certain necessary legal requirements, but not specifically to provide management information. As a consequence, the top managements of these properties work with cost data and production information that is dated, lacking in detail and clouded with supposition. It is the intent of this paper to describe an information system for a mine-plant complex in terms of the type of data, application areas and the existing equipment technology that may be applied to improve this situation. The economics of information processing and data handling will not be discussed in detail. This paper is based on the premise that information is something of value and that information processing like a manufacturing operation works for and is subject to management control. Information, the product, must be of quality, and the cost must be favorable in terms of its use.

Jan 1, 1965

By James W. Baxter

State geological surveys promote sound procedures for evaluation of mineral resources before development-procedures that protect the environment and accrue maximum benefit to citizens. Sophisticated laboratories have been equipped for geophysical, geochemical, petrographic, and mineralogic characterization of materials to assist citizens in land-use planning and optimum development of natural resources, activities clearly within purview of the state. Proper use of these facilities in support of exploration in a competitive, free-enterprise system should be based on achieving ultimate benefits to the public, but, in general, should not entail competition with commercial laboratories.

Jan 1, 1982

By Qingwen Shi, Yun Zhao, Brijes Mishra

The effect of discontinuities on the fracturing and mechanical behavior of shale has been extensively investigated on a laboratory scale in previous works. It is well agreed that the lamination properties, including discontinuity and lamina properties, affect the behavior of shale. However, it is still unclear how the lamination properties are affecting the stability of the shale roof in an underground coal mine entry. This paper investigated the effect of lamination properties using the discrete element method on a mine-scale entry model as an extension to the previous work conducted on laboratory scale models.

Jan 11, 2022

By W. K. Summers

During the past few years monitoring systems have been installed to measure the effects of environmental changes on the ground-water resource. The design of a monitoring system depends upon the designer's perception of how the environmental factors merge with his perception of the ground-water flow system. The validity and representativeness of measurements made during a monitoring program depend upon the validicy of the designer's perceptions and concepts. To optimize the design of a ground- water monitoring program the designer should make preliminary measurements to confirm his assumptions.

Jan 1, 1985

By Christian F. Baiz

The author will present a discussion of the steps which must be taken by the prospective developer of a small mining operation to establish technical credibility when seeking financial backing. Particular emphasis will be given to the differing levels of technical work (and their relative cost) which must be accomplished to supply the information necessary to satisfy potential investor groups, whether they be other mining companies, equity investors, or financial institutions such as venture capital firms or commercial banks.

Jan 1, 1981

By Cheng Li, Yanlei Wang, Lingrui Kong, Jianxin Tang, Fang Yuan

Coal mined-out areas have a significant impact on mining safety and affect the pressure distributions of neighboring coal faces. The PFC3D software is used to study the goaf mechanical characteristics, and the core loading test verifies the rationality of the numerical simulation method. The results from the numerical modeling showed that the void ratio, particle size ratio, and particle size distribution of the rock particle sample (RPS) had a significantly remarkable influence on the compression deformation characteristics of the rock block. The parallel-bond tensile strength and parallel-bond cohesion had a notable impact on the compression deformation traits of the rock block only when the axial stress level was lower than 12 MPa. By contrast, when the axial stress exceeded 5 MPa, the effective modulus significantly influenced the compression deformation features. However, the stiffness ratio, loading rate, and parallel-bond friction angle had almost no effect on the compression deformation characteristics. Furthermore, when the stress level was less than 10 MPa, the stress–strain curves from the rock core samples’ numerical simulation and loading tests were approximately linear. In addition, the Pearson correlation coefficients of the stress–strain curves suggest that the goaf zone’s core numerical simulation results had a robust correlation with the loading test results. The findings of this study can serve as a reference for the field application of PFC3D software and safety assessments in goaves.

Jan 18, 2022

By F. Ansheng

Though it becomes increasingly important with the valuable minerals in their deposits tending to be fine and poor, the solid and liquid separation remains difficult especially when the particles are of micrometer size and of low density. Almost of all conventional thickeners result in that fine particles lose into overflows which often costitutes a loss of potentially valuable resources as well as an environmental hazard. The addition of flocculations may improve the settling of solids but may also not work well for the final removal of fine particles from the overflows (Ref.1).

Jan 1, 1990

By Yun-tao Xin, Yu Yi, Kang Yan, Gang Li, Xiao-dong Lv

This study investigated the selective removal of arsenic from high-arsenic dust in alkaline systems and the effects of different leaching conditions. The results indicated that the liquid–solid ratio, NaOH concentration, and sulfur dosage had a significant influence on the process. The leaching efficiency of arsenic reached 99.57%, while that of lead was as low as 0.03% under appropriate conditions. In particular, the addition of sulfur can effectively promote the leaching of arsenic and reduce the dissolution of lead in the solutions. An artificial neural network was used to model the leaching process. It consisted of a back-propagation artificial neural network model with a “6–10–2” structure that could effectively simulate and predict the value with more than 99% accuracy. Based on the difference in weights of the different parameters in the neural network model, the relative importance of the parameters related to arsenic and lead leaching efficiency was obtained, which followed the order of NaOH concentration, liquid–solid ratio, sulfur dosage, temperature, time, and stirring speed.

Jul 29, 2021

By P. James

"INTRODUCTION High sulfate (SO4-2) levels often occur in MIW (mining influenced water) either as the result of oxidation of sulfide minerals exposed by mining activity or by deliberate addition – commonly by sulfuric acid (H2SO4) use in hydrometallurgical leaching activities. Increasing regulation of sulfate discharge is creating new pressure to treat or mitigate sulfate release to prevent its entry into the environment. Current treatments include precipitating as gypsum during lime treatment, filtration separation using membranes such as reverse osmosis and nanofiltration technology, and biological elimination via methods like constructed bioreactors. Blue Planet Strategies (BPS) focuses on improved resource utilization targeting electrolytic treatment and waste conversion into resources and has now demonstrated that its proprietary DEMET™ (Dynamic Electrolytic Metal Effluent Treatment) platform can also remove sulfate from target streams as a byproduct of its usual primary treatment focus points of metal species elimination and/or pH adjustment.[1-6] This powerful new capability can mitigate sulfate contamination and recover the sulfate in a useful and potentially saleable form as a byproduct of improved primary treatments focused on enhancing production or treating waste. This provides a new treatment opportunity and value proposition for lowering overall sulfate consumption/addition or creating new revenue to defray conventional treatment costs. The DEMET Alternative DEMET utilizes a patented electrolytic technology platform employing proprietary dynamic high surface area electrodes in innovative configurations to achieve a variety of novel selective chemistries. DEMET‘s unique elements can yield higher processing rates at practical efficiencies, lower energy consumption, plus improved processing stability and lower maintenance requirements due to enhanced resistance to cell fouling and shorting; while also thwarting cross stream (catholyte vs. anolyte) contamination. Consequently, DEMET can provide a superior, extremely versatile, and cost-effective electrolytic treatment option where a multitude of FEED and PRODUCT stream combinations might be employed in comparison to traditional tankhouse electrolytic cells. Secondary reactions (Figure 1A) which could also occur at the cathode (plating/electrowinning, precipitation/scale formation, etc.) are controlled through process tailoring and operation parameter selection. Additionally, DEMET‘s innovative dynamic system mitigates potential fouling and electrode occlusion or shorting challenges which could occur when process particulars demand some of these secondary side reactions occur."

Jan 1, 2015

By J. A. Herbst, L. B. Hales, R. Zaragoza

INTRODUCTION The Control Problem The need for automatic control in flotation plants stems from frequent and randomly occurring disturbances to the feed slurry. Typical disturbances occur in the solids feedrate, the slurry percent sol ids, and the mineralogy and flotability of the gangue and valuable minerals. In plants where semi -autogenous grinding mills (SAG) are used, feedrate changes are very large and changes in feed percent solids of 1m or more are common. Mineralogy changes between valuable minerals are common, as are changes in the host gangue rock. As these changes occur, the operator can attempt to compensate for them by making adjustments to the flotation cell levels, the dosage rates of the collectors and frothers, the pH, and in some cases the aeration rate of the cells. This problem is sometimes complicated by the fact that different sections of the flotation plant will be processing different ore types at the same time. Potential Savings with Control Flotation control brings about savings or plant improvements in two areas; the first is in improved metallurgy and the second is in reagent savings. Improved metallurgy includes increases in the average plant recovery and achieves target concentrate grade level s more consistently. Average recovery increases between 1.0 and 5.0 percentage points have been widely reported (Paakkinen, 1979; Sutherland, 1984). Reagent savings of up to 40 percent have also been reported (Hales, 1985). VARIABLES OF IMPORTANCE Control led, Manipulated, and Disturbance Variables The initial step in the analysis of the flotation control problem is identification of important variables which can affect the efficiency of separation. The efficiency of separation is represented by a group of controlled variables which can quantify the performance of a flotation circuit. This group includes variables such as grade, recovery, tonnage through- put, and circulating loads. The efficiency of separation of a flotation circuit may generally be defined by a grade recovery map, where each point on this map re- presents a set of operating conditions (see Figure 1). However, the combination of operating conditions must be set to operate close to the economic optimum. The group of operating variables which are changed in order to achieve desired circuit performance are called manipulated variables and can be classified into two

Jan 1, 1986

By James W. Mitchell

On December 2, 1942, a scientific team lead by Nobel Prize winner Enrico Fermi first initiated and controlled a self-sustaining nuclear chain reaction. This historic event occurring beneath the stands of the University of Chicago football stadium instantly created an entirely new and tremendously broad area of technology. Indeed, the event probably changed the course of world history and considering the curret energy shortage, it probably came none too soon. Following many technological breakthroughs in the ensuing years, this event led to the first full scale nuclear fueled electric generating plant. In December, 1957, the Shippingport Nuclear Power Plant became operational and the United States had entered the era of the nuclear fueled electric generating station. Today, only fifteen years later, there are some thirty-five operating nuclear power plants in the United States with another 56 under construction and 116 on order. Still, we are only scratching the surface of this tremendous energy source. In 1970, less than one-percent of the total electric generating capacity in the United States was nuclear fueled. By 1985, it is projected that 45% of our generating capacity will result from nuclear power plants. These projections are based upoa statistics of six months to a year ago and considering the current energy shortage and recent attempts by the United States Atomic Energy Commission (USAEC) to speed the licensing process and encourage standardized plants, the contribution of nuclear power to our total generating capacity may be even greater. In summary, it is obvious that nuclear power is now, and will continue, playing an important role in our future. Those factions of government, industry and the professional community charged with fully developing this tremendous energy source must deal with it rationally, logically and expediently. The various environmental considerations in nuclear plant siting play an important role in the overall plan.

Jan 1, 1974

By X. X. Shao

Dewatering of ultra-fine clean coal slurry to a low moisture level of20 percent is difficult using the conventional techniques. A novel approach, which utilized mixing of fibrous waste material, such as paper, carpet and wood, with coal slurry prior to dewatering was developed. It was found that addition of about 10 Kg/t of carpet fibers or 5 Kg/t of raw paper pulp lowered the filter cake moisture from 22.5 to 18 percent. The compressive strength of the filter cake improved from 0 to 4.5 Kglcm2 and impact resistance from 0 to 4. The experimental data indicated that the handling character of the dewatered fine coal was improved significantly.

Jan 1, 1998

By Richard S. Della Valle

Sandstone and shale samples from the Morrison (Late Jurassic) and Dakota formations (Cretaceous) from northwestern New Mexico have been analyzed for the major elements Na, K, Fe and the trace elements Sc, Cr, Co, Rb, Sb, Cs, Ba, Hf, Ta, Th, iJ and the rare earth elements (REE) in whole rock and clay sized fractions by instrumental and delayed neutron activation analysis. The clay sized fraction clearly shows enrichment patterns and halo effects ; whereas, the whole rock fraction does not. Important elemental dispersion halos associated with uranium in sedimentary environments include the REE, Hf, and Sb. The distribution of these halos are due to a combination of complexation, chelation and the orignal paleoenvironments.

Jan 1, 1984

By D. J. Beeby

California's Surface Mining and Reclamation Act (SMARA) was passed in 1975 to identify and protect mineral resources in areas of high land-use conflict and ensure reclamation of mined lands. Under SMARA, aggregate resource availability is quantified and compared to forecasted demand in specific market regions. Fifteen regions studied thus far cover 20,000 square miles and contain 50 billion tons of high-quality aggregate resources which have been legally designated as ?regionally significant?, providing a measure of protection previously unavailable. SMARA reports and State testimony at local hearings have supplied objective information and helped reduce conflict in mine-permitting decisions.

Jan 1, 1987

By R. H. King

The US coal industry has been using continuous room-and-pillar mining (CRPM) machines for more than 30 years for longwall development. This equipment has also been used for production mining in areas that are not appropriate for longwall mining. From 1977 to 1987, the portion of annual US production mined by continuous miner (CM) sections grew slightly from 65% to 70%. Over this time, mine operators and manufacturers have made some advances to attain the full production potential of this method. This is evidenced by the fact that average tons per eight hour shift for continuous miners in the US grew from 180 t (200 st) in 1977 to 431 t (475 st) in 1987. The authors (1990) reported that the increase in productivity was due to several factors: • a drop in prices; • a more mature workforce; • union stability and incentive programs; •procedural improvements; and •technological advances. The authors estimated that about one-third of the increased production came from the first three and other unaccounted for factors and one-third each for the last two. Even though improvements were considerable, continuous miner capacity is much higher than 431 t/shift (475 st per shift). For example, the machinery is capable of mining more than 9 t (10 st) per machine for the 6.5 available hours per shift or 3.5 kt (3900 st). However, this has never been attained on development. The averages of most mines are less than 900 t/shift

Jan 1, 1991