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By S. D. Thompson

Since 1965 several researchers have independently developed computer models for designing gathering belt and surge bin capacities in underground coal mine belt systems. Table 1 summarizes the models applicable to U.S. mining systems. Most of the models, employ the Monte Carlo simulation technique. Basically, the belt loading at each loading point is randomly produced from probability distributions. In some cases, a combination of deterministic calculations and probability distributions are used to simulate the loading. Once the loading is simulated, it is systematically moved through the belt system in a deterministic fashion based on belt speeds, belt lengths, and storage bin discharge rates. The coal flowing from each loading point is tracked as it moves through the belt system. When the loading from tm different sources combines on a belt or in a surge bin, checks are made to determine if capacities have been exceeded. If capacities have been exceeded the amount of spillage is calculated. At the end of the simulated time period, the cumulative spill- age is used to evaluate the belt and surge bin capacities. Naturally, a considerable amount of spillage indicates the capacities are unacceptable. Acceptable capacities are generally indicated by minimal spillage. Numerous trial simulations are often necessary to find the acceptable capacities.

Jan 1, 1987

By L. Alagha, O. Molatlhegi, S. Khatibi

"In the present study, the effect of organic/inorganic (hybrid) polyacrylamide polymer on fine coal flotation was investigated. Raw coal samples contain about 37% of ash-forming mineral at a feed size of -75 + 38 um were subjected to flotation tests in the presence of in-house synthesized hybrid Al(OH)3-PAM at different polymer dosages and pH values. Results show a significant improvement in both combustible recovery and ash rejection at 1 ppm polymer dosage. Further improvement of combustible recovery was obtained when flotation was performed at pH 5. Interfacial properties of coal particles before and after flotation were examined through electrokinetic (zeta potential) measurements of coal/water slurries. Zeta potential vs. pH curve were established and compared. In the case of raw coal/water slurry, zeta potential-pH curve resembles the ash-forming minerals (silica and clays) more than coal. After Al(OH)3-PAM-assisted flotation, the zeta potential of froth/water slurry shifted to more positive values point which strongly indicates significant removal of ash-forming minerals from coal by Al(OH)3-PAM. INTRODUCTION Coal has been a major commodity in meeting the world energy demand during the past several decades (Milici et al., 2013). According to the international energy agency, global coal demand will continue to increase for the coming decades. With increasing world population, the global electricity demand would also increase as more people would get access to basic electricity especially in developing countries (Maggio & Cacciola, 2012). Due to this increase in energy consumption, operations in coal mining and beneficiation processes have been highly mechanized to meet the demands. This mechanization has increased the quantity of raw fine coal particles produced which contain high amount of ash-forming mineral matter (slimes). Aplan et al., have reported that the major constituents of ash-forming minerals in U.S.A coal are clay minerals such as kaolinite, montmorillonite and illite (Aplan, 1997). Conventional froth flotation for fine coal cleaning suffers mainly from two major problems: 1) Low recovery of ultrafine coal particles due to slime coating by ash-forming minerals, and 2) The lack of selectivity, which results in the flotation of middlings and entrainment of mineral fines in the froth (Polat et al., 2003). Slime coating on both valuable and air bubbles have been proposed to explain the observed reduction in flotation recovery especially when fine grinding is required. In this case mineral matter may be degraded to extremely fine or colloidal sizes thereby creating difficulty in the water clarification process such as flotation. Slimes inhibit bubble-particle attachment, and increases reagent consumption due to the increase in solid/liquid interfacial area, resulting in low coal recovery."

Jan 1, 2015

An atomic force microscopy (AFM) has been applied to study the adsorption of collectors on mineral surfaces in a copper/molybdenum flotation system. AFM images show that collectors absorb on chalcopyrite surface in patches at pH 11. A study of temperature effect on surface morphology excludes the possibility that these patches are nanobubbles forming on hydrophobized mineral surface. Hydrocarbon oil absorbs on molybdenite quickly, while KEX (potassium ethyl xanthate) has little affinity for molybdenite. Pyrite is much more reactive in water and its surface is easily coated in Ca(OH)2 solutions at pH 11. Based on the obtained AFM images, the adsorption of chemicals on mineral surface and its impact on copper/molybdenum flotation were discussed.

Jan 1, 2012

By J. M. Christian

Silver has been a much maligned metal in recent years. In the last three and a half years the price has fallen from around US$7.00 -$7.80 to as low as $3.50 this spring. It has consistently under-performed most other precious metals in the past few years, and has fallen to its lowest levels since the late 1940s in inflation-adjusted terms. Perhaps this is beginning to change. Since April, silver prices have outperformed gold and platinum. While this may continue in the years ahead, key questions remain regarding the pace and timing of any future silver price advances. I want to talk about the supply and demand factors that have led silver to its recent position. Also, I will outline a possible path for silver supply, demand, and prices for the next several years. Before I dive into my discussion of the silver market, allow me to explain who I am. One of the points we always make to clients early in a relationship is that, when you are listening to someone's opinions, you always must remember who it is you are listening to, and why he might be saying whatever it is he wants you to hear. So often, people take opinions from brokers, traders, or investment advisors as gospel truth, never stopping to ask themselves two key questions: Is there any reason to believe that this person knows what he is talking about, and, second, is he trying to sell me something, in telling me this.

Jan 1, 1992

By D. Hodouin

Abstract. Dynamic experiments were performed in a continuous open-circuit 40x40 cm ball mill using a pseudo-random binary sequence of the feed rate and measuring the variations of the discharge particle-size distribution. The impulse response is calculated by a cross-correlation technique. Then a model involving a discrete transfer function and a time-series stochastic equation is calibrated using maximum likelihood methods. Based on this empirical model. a minimum variance controller with constrained input is designed and its performances are compared. by simulation, to the performances of a conventional PID regulator.

Jan 1, 1987

By E. Sabina Brady

Over the next two decades there will be significant trade and development opportunities in China for mining, engineering, equipment, and construction companies interested in becoming part of the development of China's chemical and fertilizer industries. At last count, China's phosphate ore reserves of 11.8 Gt (13 billion st), ranked fourth in the world behind the US, the USSR, and Sahara-Morocco. However, a recent statement by the head of the Ministry of Geology and Minerals, Sun Daguang, claims that with increased prospecting in the last few years, China's phosphate reserves now rank first in the world. Whatever the actual size of its known and potential reserves, China's present phosphate processing capabilities fall far short of demand, while the substantial progress that has been made in this area points out the severity of the problems that still remain. Since 1949 China has developed 181 mines and increased its phosphate concentrate production from 10 kt (11,000 st) to 10.86 Mt (11.97 million st). By the 1980s, China was the third largest chemical fertilizer producer in the world-although this claim is slightly misleading as China's nitrogen/phosphate potassium ratios are far from average world ratios and even further from US standards. According to the Sixth Five Year Plan promulgated in 1982, the country's development plans emphasize the expansion and upgrading of key energy and industrial sectors, including that of fertilizer production-specifically phosphate and potash. Within the framework of the plan, the Ministry of Chemical Industry's development priorities are to: • Increase potash production by 150% to 50 kt (55,115 st). • Raise phosphate fertilizer production 21.2% to 2.8 Mt (3.1 million st), 46 kt (50,705 st) of which will come from new projects constructed and completed within the Sixth Five Year Plan, with projected new production of phosphate concentrate and complex fertilizer in the next decades totaling 500 kt (551,146 st). • Commence work to increase phosphate ore production by 8.33 Mt (9.18 million st). Facilities for 2.43 Mt (2.68 million st) will be completed and come on stream by 1985. • Commence work to increase iron pyrite ore production by 3.69 Mt (4.07 million st), facilities for 2.9 Mt (3.2 million st) will be completed and come on stream by 1985. • Verify 600 Mt (661 million st) of new phosphate ore reserves. Since the promulgation of the Sixth Five Year Plan, Chinese authorities have announced that 70 key construction projects will receive top priority in the implementation of the plan. These projects include five in the chemical industry area, including the construction of four fertilizer plants in Urumqi (Xinjiang), Zhenhai (Zhejiang), Beijing, and Lucheng (Shanxi), and a pyrite mine in Yunfu (Guangdong). In addition, by 1985 the state will expand or construct three major phosphate mines: Wangji in Hubei, Kaiyang in Guizhou, and Kunyang in Yunnan. Fertilizer Ratios In 1982, China's fertilizer production was slightly higher than 12 Mt (13.2 million st) and consisted of 80% nitrogen, 19% phosphate, and 0.19% potassium. By 1985, state officials project that fertilizer production will reach 13.4 Mt (14.8 million st) and consist of 78.4% nitrogen (10.5 Mt or 11.6 million st), 21.2% phosphate (2.8 Mt or 3 million st), and 0.39% potassium (52.3 kt or 57,605 st). To attain the world average using the country's 1985 projected production level for nitrogen, China will have to double its 1985 phosphate production to 5.76 Mt (6.35 million st) and increase its 1985 potassium production almost 80 times to 4.1 Mt (4.5 million st). These numbers demonstrate the seriousness of the fertilizer production problem in China today and the long-term nature of the problem's solution. Development Examples Yunnan is the third largest phosphate-rich province in China with verified deposits of 1.9 Gt (2.1 billion st). Despite this abundance, the province only mines around 3 Mt (3.3 million st) of phosphate rock annually. In June of this year, Yunnan announced its intention to initiate 39 development projects within the next two and a half years, requiring an estimated $200 million worth of foreign investment. The three areas receiving the most emphasis will be:

Jan 9, 1983

Remote sensing methods have been used to evaluate vegetative growth patterns for many applications, though relatively little work has focused on tracking mine reclamation progress. For coal mines in Central Appalachia, reclamation approaches that include production of biofuel feedstocks are increasingly attractive, as these may yield significant post-mining land values and contribute to carbon-neutral energy supplies. To optimize biomass productivity, the influence of reclamation practices on biomass production must be well understood, which necessitates tracking biomass production over long time periods. Satellite-based estimations may offer low-cost alternatives to conventional biomass estimations and, also, the potential to provide critical input for carbon accounting at varied spatial scales. In this paper, experimental biomass production plots on reclaimed mine sites established in Wise County, VA, are used for a comparative study of satellite spectral derivatives, which are evaluated against groundbased biomass estimates. Metrics based on four spectral derivatives, band ratios and spectral transforms were regressed against biomass measured in situ for different species. The results demonstrate that greenness and principal component 2 (PC2) were more efficient than the other spectral derivatives for monitoring the biomass of this reclaimed area. Also, it is shown that Landsat-5 TM has provided promising results for monitoring of the biomass changes occurring from 2008 to 2010 over the study area.

By John Rajala

The Otjikoto Gold Mill was commissioned during November–December 2014 as Namibia’s first new gold producer in 30 years. Its operations consist of surface mining with a modern gravity/carbon-in-pulp mill for ore treatment and gold recovery. The initial mill design capacity was 2.5 Mt/a. Its capacity was expanded after nine months of operation to 3.1 Mt/a, and process performance has significantly surpassed design expectations. After startup, the Otjikoto Mill’s throughput and gold recovery ramped up quickly, with both parameters exceeding design after only two months of operation. The robust process performance continued into 2019, with key performance indicators (KPIs) eclipsing design values in almost every aspect of mill operation. The Otjikoto Mill’s gold recovery is exceptionally high, exceeding 98 percent every year following startup, especially considering the low-grade nature of the deposit.

By Basil W. Mercer

Increased emphasis on industrial pollution control has intensified investigation of waste treatment technology for methods of reducing the amount of pollutants discharged by industry. The mining and mineral processing industry can point to a record of considerable accomplishment in the field of wastewater treatment and reclamation because these operations are so frequently an integral part of the entire operation of an ore dressing facility. This is amply demonstrated by metal producers in the arid regions of the Southwest where water shortages require maximum use of available water. For example, the copper industry in Arizona during 1960 employed an estimated 184 billion gallons of water of which 87% was reused water. (1) Only 0.0003% was discharged to streams and the remainder was consumed by evaporation (8%) and seepage (5%). The most severe pollution problem facing the mining and ore processing industry today is that resulting from acid mine drainage. This problem is largely associated with the mining of coal although it occurs to a lesser degree with the mining of other materials. The degradation of streams by acid mine drainage in the vicinity' of the Appalachian coal fields has been widely publicized and a major effort is underway to determine the best means of correcting this situation. Other forms of pollution from mining operations are less well-known, but it is anticipated that improved or advanced waste treatment techniques will be required for segments of the industry to comply with new pollution control regulations. The current emphasis on redefining hazardous levels for heavy metals and various chemicals with regard to the total environment will in all likelihood lead to tighter discharge controls in some cases. It is the purpose of this paper to review some of the waste

Jan 1, 1971

By Y. Nakahiro, T. Wakamatsu, M. S. Elsalmawy

The flotation of quartz, feldspar and alumina was studied as a function of pH when using N-alkyldiamines as collectors. The lengths of alkyl chains of diamines were 8, 9, 10, and 12 carbon atoms. It was found that shorter hydrocarbon chain length of alkyldiamines has stronger tendency to float quartz while the feldspar responded poorly to flotation with these collectors at high pH values. The effect of addition of nonionic surfactant of Brij type, when using dodecadiamine as collector, was investigated. Flotation studies in the absence and in the presence of sodium dodecylsulfonate were carried out. These studies have indicated that sodium dodecylsulfonate, in the concentration studied, functions as strong depressant for feldspar.

Jan 1, 1995

By Swati Mohanty, G. V. Rao

Sedimentary dolomitic phosphate ores are difficult to treat by flotation, and high-grade phosphate concentrates with high recoveries are difficult to obtain. The literature indicates that the reagents required for beneficiation of such ores are generally dictated by the nature of the gangue. In this paper, the optimum flotation parameters necessary for enhancing the grade and recovery of a typical low-grade dolomitic rock phosphate ore from Jhamarkotra, Rajasthan, are highlighted. The standard design-of-experiment (DOE) technique was used to obtain empirical models for both grade and recovery. The model equations were then used for optimizing the flotation parameters, including pH, percent solids, collector dosage and depressant dosage. Laboratory experiments demonstrated that a phosphate concentrate containing about 36% P205, with a recovery greater than 95%, can be obtained in a single-stage by the reverse flotation of carbonaceous minerals at the optimized conditions. Key words: Phosphate, Flotation, Dolomite

Jan 1, 2003

By John N. Murphy

The past five years have seen communications techniques and hardware developed by the Bureau of Mines and its contractors increasingly brought into use in U.S. mines. The Bureau of Mines philosophy has been to help develop and introduce new hardware that goes as far as possible toward meeting the mining industry's needs. The Bureau of Nines programs are also designed to provide continuous fallout of new communications capabilities which are introduced to the mine operators as they occur. As more progress is made in meeting mine comnications needs, it is hoped that the mining industry will readily adopt the equipment and techniques that it finds most useful in meeting its individual needs. This paper reports on recent advances achieved in the development of improved nine communications systems.

Jan 1, 1976

Despite two large projects represented in the keynote docket, the mood of the 2011 SME Arizona Conference was summed up best by Ferol Baker, general manager of New Mexico Copper Corp. (a wholly owned subsidiary of Themac Resources Group), ?In the past, it seemed like you couldn?t go to a conference like this without hearing about one big new greenfield project after another. Now what you see is companies doing internal expansion or small-scale brownfield development.? Overall, the tone of this year?s meeting, held at the J.W. Marriott Resort at Starr Pass in Tucson, AZ, was upbeat, yet practical. From the keynote and luncheon addresses to the six panels of sessions, the projects described were positive about the future, yet focused on the details required to make those projects come to fruition.

Jan 1, 2012

By J. M. Beck

Mineral property appraisers engaged in eminent domain actions on properties for which mining is the highest and best use must be fully competent in all phases of mineral resource estimation, mine project development, and mine operations (or retain the requisite competent assistance), as well as educated in eminent domain appraisal (USPAP Competency Rule). Failure to ensure such triggers the issue of appraisal competence and demonstrates a flagrant disregard of the myriad code(s) and guidelines to which the appraiser is subject. The cavalier assertion of some vague, undefined “latitude” in the valuation process does not exonerate the appraiser from a disregard of the USPAP Competency Rule. Lack of independence (i.e., “advocacy”) in mineral property appraisal is the usual result of a weak background in mining and/or appraisal theory. While it is readily apparent to those able to recognize it in reports and testimony, judges and juries cannot be expected to detect or recognize purposefully misleading (or even fraudulent) valuation concepts or testimony. Purposeful deception by the appraiser can lead to specious over-compensation of the property owner (thus victimizing the taxpayer); or, a failure to provide appropriate and just compensation to the property owner – yet, the purpose of an eminent domain proceeding is to leave the property owner no richer or poorer as a result of the taking. This paper highlights some of the deceptive practices encountered in litigation settings and raises issues of competency, professional ethics, and the effectiveness of the inherent enforcement capabilities within those institutions awarding professional certifications. INTRODUCTION The practice of eminent domain mineral property appraisal requires (particularly with respect to undeveloped mineral properties) that the appraiser possess the requisite level of competence in all phases of mineral resource estimation, mine project evaluation, mine development, and mine operation (through closure). To the extent the appraiser lacks such competence, it is incumbent on the appraiser not only to divulge this lack of expertise but also to seek competent assistance in the performance of the appraisal. This competence or expertise can only be obtained through a combination of appropriate and relevant technical education and direct mining industry experience. There exist a number of professional certification and/or credentialing authorities that speak to such competency. In a similar manner, eminent domain mineral property appraisal (as the term implies) also requires that the appraiser possess the requisite level of competence in the practice of eminent domain appraisal. This competence or expertise can only be obtained through appropriate and relevant education, direct knowledge of appraisal theory, particularly as it relates to the concept of eminent domain, and licensure.

Jan 1, 2019

By William Gleason

While a fleet of 100 t (110 st) haul trucks were busy removing overburden from the open pit mine in the distance, a host of dignitaries, including congressmen and California state representatives, gathered for Molycorp?s official groundbreaking ceremony at the Mountain Pass Mine on April 20. The mine, recognized as arguably one of the richest rare earths deposits in the world, is at the center of Molycorps? strategic ?Mine to Magnets? plan. It aims to secure America?s future supply of rare-earth-dependent technologies by developing a strong domestic rare earth industry. Molycorp identifies rare-earth-dependent technologies as those that cannot be produced without rare earth materials. The list of these technologies is long and growing. It encompasses everything from personal electronics and batteries for hybrid cars to permanent magnet generator wind turbines and national defense applications.

Jan 1, 2011

By E. G. dos Santos, M. M. Veras, C. H. Sampaio, A. S. Young, R. S. Paranhos, C. O. Petter, A. C. Bastos

"The major challenges of the current mining are the energetic optimization, the lowest water consumption and minimizing environmental impact. One technique that eliminates much of the waste avoiding milling sterile, operating without water and to decrease the generation of waste at the end of the process, must be considered a major innovation. One of the most important developments in these past 10 years in the mining industry was expanding the use of high-tech sensors aimed at pre-concentration of ore. Among the mining areas where this type of technology is booming is the industrial minerals. The most common sensors are color sensors with Charge – Coupled Devices (CCD cameras) allowing through the RGB colorimetric system, the separation of minerals with different hues, and in many cases, a difference in brightness. More recently, the development of the use of dual energy X-ray transmission (DE-XRT) Dual Zone allowed the separation by atomic density of the mineral constituents of the rock. This paper presents a review of these two techniques (CCD and DE – XRT) as well some results showing the use of these two techniques for Earth Rare and Limestone. INTRODUCTION The mining industry is going through one of its biggest technological changes since the industrial revolution by the implementation of new technologies, according to Australian Mining Magazine (2015), whose theme emphasized one of the 10 greatest challenges that mining will face in the coming years. Optimization of the energy matrix in mining is focused on reducing water consumption and minimizing environmental impacts. The implementation of sensor technologies (Sensor-Based Sorting - SBS) allows elimination of mill tailings and permits the mill to operate with reduced use of water or totally eliminate this consumption (Young et al, 2016). According to Jönsson (2014) mining has undergone striking changes with the expansion of sensors of high technologies applied in the pre-concentration of mining ores. These techniques have contributed over the past 10 years in the recapture of mining areas with emphasis on the environment and/or operational optimizations. In line with the requirements of technological innovation, the mining industry is forced to make improvements in gravimetric processes ensuring better levels of Run of Mine ore feed in beneficiation plants. The implementation of automatic sorting, assisted by dual energy x-ray transmission (DE-XRT) sensor technology, or charged coupled device (CCD) image capture camera technology in the feed plant, allows for the selective sorting of individual particles into pre-concentrations (Veras et al, 2016)."

Jan 1, 2017

By Richard R. Klimpel

INTRODUCTION The purpose of this paper is to summarize the current status of reagents used in the mineral industry plus present some current challenges and possible new technologies of the future. Table 1 lists the important families of reagents which, when taken together, constitute at least 95% of the current commercial reagent market. A very approximate estimate of the free world reagent market size in mineral applications is about 1.5 to 2.0 billion dollars (U.S.) using 1985 data. Obviously, to serve such a large market requires the effort of many different types of commercial supply sources. It is estimated that there are over 300 industrial firms in the free world that have a dedicated business/technical structure for supplying reagents related to the mining industry. There are a number of characteristics which are associated with the product families listed in Table 1. Understanding these characteristics helps to provide a realistic economic/technical basis for outlining future challenges in mining chemicals. 1.Essentially all of the products listed are old chemistry in the sense that the molecules have been known and manufactured for at least 25 years. This has not been a highly dynamic field of endeavor from the viewpoint of new product introduction. 2. The greater majority of the products listed can be viewed in commercial terms as "commodity" chemicals, that is, they are available from many sources and the pricing of a some- what generic product generally dominates differences in product quality or uniqueness. With commodity pricing, reagent suppliers significantly reduce research expenditures, loosen product quality somewhat if the applications of the reagents allow, etc. in order to be cost competitive.

Jan 1, 1989

By T. J. De Mull

The Alligator Ridge Mine is located 70 miles northwest of Ely in White Pine County, Nevada. Development of the mine began in the late 1970's as a joint venture between Amselco Minerals, Inc. and Occidental Minerals Corporation, with Amselco as the operating partner. Early in 1983 Nerco Minerals Company acquired Occidental's share of the property. The mine and ore processing facility have operated at capacity since 1981 producing 680,000 tonnes of ore and 1,900 kg of gold per year. The gold ore deposits at Alligator Ridge consist of disseminated micron-size gold particles in a silicified siltstone matrix. The deposit comprises three separate but adjacent areas of mineralization that are designated as Vantage 1, Vantage 2, and Vantage 3 after the name of the basin in which the deposits lie.

Jan 1, 1983

By Robert Bohman

I truly free enterprise system requires free and unrestricted competition among a diversity of suppliers, in order to function properly. The natural attrition of the marketplace tends on the one hand to narrow the competitive field ... but the flow of new competitors entering the arena provides a "diluting" effect, and a "balanced" market place. Without the ready flow of new business entrants, the market becomes increasingly concentrated in the hands of fewer and. fewer firms. Competition among suppliers is diminished and the "free" marketplace suffers accordingly. A number of organizations, both governmental and private, have recently expressed grave con¬cern over the competitive future of the Western coal market. While most have noted that there is currently adequate competition within the Western market, some have cited the growing con¬centration of coal ownership ... particularly federal lease ownership ... in the hands of a relatively few firms. They suggest that unless this apparent trend is reversed or at least stemmed, the number of new firms entering the federally-dominated West may become reduced to the point where competition will suffer.

Jan 1, 1982

By Peter W. Harben, Edward M. Dickson

The distribution of metallurgical grade bauxite deposits will be discussed with the aid of a comprehensive table and a reference map. Information will include operating companies, mine locations, ore grade, and chemical analysis, geological environment, and production capacities. General comments will be made on the distribution of production and its relationship with major consuming regions. The pattern for the future will be assessed, including potential new producers, changing specifications and industry structure.

Jan 1, 1984