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By R. Sellaro, E. Sarver

It has long been understood that extended occupational exposures to respirable mine dusts can lead to chronic lung disease. In underground coal mines, coal workers pneumoconiosis (CWP) and silicosis are major concerns. While many efforts have been made with the aim of understanding the mass-based concentrations and silica contents of respirable dusts under a variety of mining conditions, little research has been completed in characterizing dust at the individual particle level (by composition, size and shape). This study employed scanning electron microscopy with energy dispersive x-ray (SEM-EDX) to analyze dust samples collected from an underground coal mine in Central Appalachia. The results indicated that particle characteristics can vary widely between locations, though many trends might be explained based on knowledge of mining conditions. A continuous personal dust monitor (CPDM) was also used during the collection of some samples to determine respirable dust concentrations, which were compared against estimated concentrations based on the particle-level analysis.

Jan 1, 2014

THE opening session was held on Tuesday evening, February 17th, in the house of the American Society of Civil Engineers. The President of the Institute, Mr. E. B. Coxe, after a few introductory remarks, congratulating the members on the general prosperity in all the branches of the professions and manufactures represented by the Institute, called on Mr. E. F. Loiseau, of Philadelphia, for the first paper, On the Successful Manufacture of Compressed Fuel at Port Richmond, Philadelphia. Professor Prime called attention to the fact that the work of the United States Testing Board had been left unfinished at a point when valuable results had just been reached, and offered the following resolutions: WHEREAS, The American Institute of Mining Engineers has seen with regret that the work of the United States Testing Board has been suspended through the lack of an appropriation by Congress, which appropriation dues not seem likely to be renewed, and WHEREAS, It seems most important to the vital interests of our iron and steel manufactures that the experiments commenced by the United States Testing Board should be carried to successful completion ; Resolved, That a committee of three be appointed, to act with a like, committee to he appointed by the American Society of Civil Engineers, to carry out to completion the work commenced by the United States Testing Board. Resolved, That the American Society of Civil Engineers be requested to cooperate with this society by the appointment of a like committee. Resolved, That the committee have authority to request, in the name of the American Institute of Mining Engineers, contributions to a fund to be devoted to the completion of the experiments aforesaid. Resolved, That the Council of this Institute be authorized, whenever requested by the committee so appointed, to petition Congress for the free use of the testing machine at the United States Arsenal at Watertown. Resolved, That a committee be appointed by the President, to select the afore-said committee of experts. Resolved, That the President of the Institute have authority to fill any vacancies which may occur in the committee. The resolutions were unanimously adopted, and President Coxe appointed the following committee in accordance with the resolutions : Messrs. A. L. Holley, James Park, Jr., and J. F. Holloway. The President also appointed Messrs. Heinrich, Mickley, and Spils-

Jan 1, 1880

By Richard J. Robbins

Mechanical moles have developed through a tedious process of evolution. At times it has seemed that tunnel borers have been subject to the same Darwinian rules of evolution as their zoological namesakes who, despite their efficiency, are highly specialized and still restricted to soft soil conditions near the surface of the ground. HISTORICAL HIGHLIGHTS The Robbins Co. began its work in this field in 1947 with the development of a twin-bore continuous coal miner. Although these machines were used primarily in coal, two of the early prototypes were used to bore tunnels through shale. Disk cutters were first used on these machines and showed promising results as core breakers between drag-bit kerfs. In 1953, James S. Robbins and Assocs. undertook the development of a 25-ft 9-in.-diam circular tunnel borer for Mittry Construction Co. to be used at Oahe Dam in South Dakota (Fig. 1). This is believed to be the first rock tunnel-boring machine built since the end of the 19th century when short sections of the Channel tunnel were successfully bored in chalk from both the English and French shores. Another Oahe Dam machine was built in 1955, and then a series of three small-diameter machines for the company's first real experience with medium-hard and hard rock (Fig. 2) None of these three could be considered a success, although they laid the groundwork for the success that followed. Interbedded shale and limestone in Pittsburgh and hard limestone in Chicago quickly pointed up the weaknesses in these machines which were used by Perini, Dravo, and Healey. Among the problems were the high breakage rate of tungsten-carbide drag bits, too much flexibility in the drive shafts, failure of high-pressure hydraulic systems, chain-conveyor failure, and general lack of rigidity and strength. In 1956 another attempt at medium-hard and hard rock-boring proved this time to be a success and a significant turning point in the development

Jan 1, 1970

By W. D. Mcmillan

The Dempsey tract in Washington County, Mo., had a small production of lead-zinc ore from shallow workings. Old dumps from early-day lead mining contain about 25,000 tons of ore averaging about 3 percent combined zinc and lead. Because of the urgent war requirements for lead and zinc, the Dempsey property was examined by Otto Ruhl, formerly an engineer of the Bureau of Mines in August 1942 and selected for further investigation by churn drilling twenty holes totaling 1,309 feet were bored in the fall of 1943. The results of the work are presented in this paper.

Jan 1, 1948

By Enid C. Plante

To extend our knowledge of the flotation behavior of sulphide minerals, the response of the following minerals to ethyl xanthate as collector was studied by captive bubble and cylinder flotation tests: antimonite (Sb2S3), arsenopyrite (FeAsS), covellite (CuS), rnarcasite (FeS2), orpiment (As&.), pyrrhotite (FeS) and tetrahedrite (4CU2S, Sb2S3). Lollingite (FeAs2) was also exarnined to determine if its behavior could be correlated with that of pyrite or rnarcasite (FeS2. Experimental Method Mineral for Flolation and Contact Tests Mineral was prepared in the manner a1ready described1 and its behavior both freshly ground and "oxidized" was studied. Tests in which the mineral was allowed to oxidize for various periods showed that a uniform response to xanthate was reached in two days or less. Oxidation Products The soluble oxidation products from most of the above minerals were measured and their effect on the flotation of the mineral studied. The mineral samples were wet ground to minus-52 mesh and deslimed, and 20 g of this material placed in 200 ml of distilled water of a measured pH value, and CO2-free air bubbled through each suspension at a constant rate (about I bubble/sec) for 5 days. It has been shown1 that the size of the mineral is unimportant in the rate of formation , oxidation products and that probably the supply of oxygen to the mineral is the rate-determining step. At the end of 5 days the pH value of the 'supernatant liquid was measured again, the mineral filtered off and the soluble products determined. Methods for estimation of sulphur acids, ferrous and ferric iron and copper have already been described.l No satisfactory method was found for antimony. Arsenic was estimated as the arsenate.2 Flotation of "Unoxidized" Minerals with Ethyl Xanthate as Collector Fig I to 3, 4. 6, show the effect of alkali and cyanide as depressants for the minerals with 25 mg potassium ethyl xanthate per liter as collector at 35°C. Wark and Cox8 have shown that with ethyl xanthate as collector, galena, pyrite and chalcopyrite show a greater tolerance to cyanide and hydroxyl ions at room temperature than at 35°C Covellite (Fig I), marcasite (Fig 2) and pyrrhotite (Fig 3) behave similarly. The independence of the curves for pyrrhotite at 35°C with respect to cyanide

Jan 1, 1949

By Paul E. Rosten

This paper describes some of the latest improvements that have been incorporated or planned by the Cleveland-Cliffs Iron Company to reduce operating costs and improve pellet quality. The Cleveland-Cliffs Iron Company operates and manages mining, beneficiation, and pelletizing operations in Michigan, Canada, and Western Australia. This paper deals with the grate-kiln pelletizing operations at Republic, Humboldt, Tilden, Empire, and Pioneer in Michigan, and the Adams and Sherman in Ontario, Canada. Table I characterizes .each operation in regard to location, ore type, pellet capacity and date that pellets were first produced. All of the operations with the exception of Pioneer and Tilden, utilize downdraft-two-pass grate cycles of drying followed by preheating. Pioneer utilizes an all-downdraft, three-pass grate cycle which consists of three drying zones followed by the preheat zone. The Pioneer and Tilden cycles have been described previously. (1) (2)(3) Tilden utilizes a three-pass grate cycle with a stage of updraft drying, followed by two downdraft drying stages. Recuperation systems which supply hot gases to a drying zone from second stage cooling were designed and furnished for Tilden I. Tilden II will be identical. Empire IV will also be furnished with a recuperation system. The Adams grate-kiln system was retrofitted with a recuperation system. This paper will summarize some of the efforts that are in effect or planned for grate-kiln pelletizing systems to (1) reduce operating and maintenance costs, (2) reduce energy requirements, (3) improve product quality, and (4) meet environmental standards.

Jan 1, 1977

The Carboniferous sedimentary rocks of southwestern Newfoundland merit investigation because of petroleum, salt and gypsum possibilities and indications of base metallization along the equivalent of the Horton-Windsor con-tact. In this paper, Lower Mississippian (Anguille) strata are divided into three formations: (1) the Cape John below, (2) the Snakes Bight and (3) the Seacliffs. A correlation between these formations and the Craignish, Strathlorne and Ainslie formations of the Horton group? in western Cape Breton Island is suggested. The criteria for the Anguille subdivision are essentially lithological, but preliminary study of included spore assemblages suggests more precise interformational correlations between Anguille and Horton sequences. The re-measured lower portion of the type section of the Codroy group is presented to define more clearly the stratigraphic position of numerous gypsum and limestone beds. Because of rapid facies changes within the Codroy group a simplified two-fold division into upper and lower units is proposed on the grounds of

Jan 1, 1964

By C. Y. Garber

INTEREST in the sink-float plant operated by the Bunker Hill and Sullivan Mining and Concentrating Co. at Kellogg, Idaho, has recently been largely confined to the preparation and reconditioning of the galena medium. The ease and simplicity of these operations in a concentrating mill producing a flotation lead concentrate has occasioned enough comment to possibly justify a brief description. The subject is treated from an operator's viewpoint only; no effort is made to discuss it in a theoretical or technical manner. PLANT AT BUNKER HILL The sink-float plant was first operated in December 1941. It was built for the purpose of quickly increasing mill capacity with a minimum of equipment. It is the Huntington-Heberlein sink and float process using galena medium and is operated under license from the Sink and Float Corporation, New York city. Lead-zinc ore from the Bunker Hill mine is crushed to pass a I ¼ in. screen and is then washed and separated on vibrating screens having 4 ½ -mm. round-hole punched plates. The screen undersize, amounting to 33 per cent of the mill feed, is dewatered and sent to the ball-mill feed bins. The screen oversize goes to the sink-float plant, where 50 per cent of the oversize, or 33 per cent of the mill feed, is float, which is washed free of medium and disposed of as a tailing. The remaining 33 per cent is sink, which, after washing, is crushed to pass ½ in. and joins the undersize in the ball-mill feed bins. The normal plant capacity is 1700 tons per 24 hr. About 1.7 per cent of the total lead and 3.3 per cent of the total zinc in the feed is lost with the sink-float tailings (Table I). [ ] More complete descriptions of the H. H. process and Bunker Hill sink-float plant are given in several recent articles, listed at the end of the paper. PREPARATION OF MEDIUM AT BUNKER HILL New medium is made intermittently as needed, usually 12 hr. in each 6 days. A small portion of the current mill flotation concentrate is diverted from the lead cleaner cells to a I-in. vertical sand pump and pumped to a two-cell 36-in. Agitair flotation machine, where NaCn and ZnSO4 are added and the grade of concentrate is improved as shown in Table 2. Tailing from this operation is returned by gravity

Jan 1, 1946

By M. R. Geer, H. F. Yancey

Four coals were treated in the Humphreys spiral concentrator, and the products were examined by float-and-sink and screen-sizing tests to determine fundamental performance characteristics. The efficiency of the separation between coal and impurity was shown to be influenced greatly by particle size.

Jan 1, 1950

By Mario Mauro, Jeff Taylor, Carlos Morales

"In 2007 the US Army Corps of Engineers classified the Herbert Hoover Dike in Florida as a Dam Safety Action Classification (DSAC) 1 dam, and started the implementation of one of the largest dam rehabilitation projects in the nation. The construction of the cutoff wall is a key feature of this rehabilitation work to upgrade the dike to current dam safety criteria. The cutoff wall installation is currently being completed on Reach 1, which extends from Port Mayaca to Belle Glade, under a Multiple Task Order Contract based on performance specifications and stringent verification criteria.For the construction of the cutoff wall TREVIICOS selected the self-hardening slurry method. Since the cutoff wall is installed through a layer of highly variable limestone with Unconfined Compressive Strength (UCS) up to 14,000 psi, the excavation requires the use of the hydromill equipment. This is the first successful application of the hydromill technology with self-hardening slurry in a large scale project in the US. This paper presents the details of the method utilized, the quality control procedures, and the experience gained over seven miles of cutoff wall installed.INTRODUCTIONProject LocationThe Herbert Hoover Dike (HHD) system, around Lake Okeechobee in South Florida, consists of a series of levees, culverts and locks and is approximately 143 miles long (Figure 1).Lake Okeechobee is the second largest freshwater lake in the lower 48 states of the United States. The lake is the primary drinking water source for numerous communities around the lake and to millions of people living along the lower east coast. The lake is also a vital source of irrigation for the agricultural industry in the South Florida region.Lake Okeechobee is 33 miles wide from north to south and 30 miles wide from east to west and has a surface area of 730 square miles. The average water depth of the lake is 9 ft."

Jan 1, 2017

By P. M. Daling, C. A. Geffen

The objectives of this study were to examine a representative cross section of formal safety analysis techniques developed for the nuclear and aerospace industries, to recommend those methods that would be suitable for application to the mining industry, and to include those methods in a user's manual. Volume XI of this report, the user's manual, describes several methods that were determined to be immediately transferrable to the mining industry. The handbook gives detailed instructions on appropriate application and utilization of the methods. Other techniques will require further development before they can be effectively transferred to the mining industry.

Jan 1, 1983

He took a great interest in technical matters and his inclination was strongly toward research investigations. At the same time he was effective in manual and mechanical work and was generally found working side by side with the men under his direction. His nature was unselfish and he was extremely popular socially. He was a member of the Coeur d'Alene Commandery, Knights Templar. Stanly A. Easton. Lieutenant.Louis Baird Louis Baird, a Lieutenant in the Royal Field Artillery of the British Army, died on the battlefield in 1915. Lieutenant Baird was born July 28, 1880, at Stirling, Scotland. His technical education was obtained at King's College, Melbourne, Australia, in 1893 to 1895, and at the Technical College at Glasgow, Scotland, in 1897 to 1900. After an apprenticeship with the Mexican J. & 8. Rec. Co. of Mexico, lasting from 1900 to 1903, he became mill superintendent for the Cia. Minera Benito, at Juarez, Zac. During the year 1905-6 he was assistant manager of the Candelaria y Anexas, at Pinos, Zac., and from 1906 to 1907 was engineer with the Cia. Minera Jalisco, San Sebastian, Jalisco. At the time of his admission to the Institute, in 1908, he was practising as a mining engineer at Etzatlan, Jalisco, Mexico. For the next four years he practised his profession in the City of Guadalajara, Jalisco, removing, in 1913, to Ixtlan del Rio, in the State of Tepic. It was from here that he returned to England to put his services at the disposal of the British Government. The Institute is not definitely informed as to how, where, or when Lieutenant Baird met his death. Captain John H. Ballamy John H. Ballamy, Captain on the Regimental Staff of the 103d Engineers, was killed near Fismes, on Aug. 9, 1918. Captain Ballamy was born at Plvmouth. Pa.. in 1886 and graduated from' the High School of that town in 1903. In the following year he began work as a coal miner, and at the same time began the study of mining engineering in the evening and any other spare time. He continued this diligent and energetic practice for many years. For sixteen years he continued in the employment of the Delaware, Lackawanna & Western Rai1roa.d Company's coal mining

Jan 1, 1920

By G. R. Hopkins, E. W. COCHRANE

The number of completed petroleum refineries in the United States continued to decline in 1937 , but the total capacity to process crude oil continued to increase . These facts were ascertained in the Bureau's annual canvass of refinery capacity as of January 1 , 1938 . Several important changes were made in the census questionnaire for January 1 , 1938 . First , the basis of reckoning cracking capacity was changed from cracking stock charged to cracked gasoline produced . Although this is a definite improvement , in that it is no longer necessary to consider the yield , it is unfortunate that the data for January 1 , 1938 cannot be compared with cracking - capacity statistics since 1925. Other changes or additions included separating capacity at operating plants into that actually operating and that closed down ; collecting data on capacity added or retired during the previous year ; breaking down idle capacity according to physical status ; and separating new capacity into that built for replacement and that built to augment existing capacity . Prior to January 1 , 1938 , the total capacity of an operating plant was listed as " operating " even though some stills might have been closed down ; furthermore , the only capacity reported as being under construction was that of new plants that were being built on January 1. To make the statistics clear , the totals for the United States as of January 1 , 1938 , are given on both the old and the new bases . On January 1 , 1938 , there were 551 completed plants compared with 572 the previous year . Ten new plants were under construction on that date compared with 11 the year before . The greatest number of completed plants recorded was 632 on January 1 , 1936 ; since then , competitive conditions , particularly in the East Texas field , have been instrumental in reducing the number of small independent plants . The total crude- oil capacity of the completed refineries on January 1 , 1938 , was 4,351,151 barrels , of which 3,970 , 196 barrels ( 91 percent ) represented the capacity in actual operation and 380,955 barrels ( 9 percent ) was shut down . The " shut -down " capacity ( 199,875 barrels on the old basis ) was the lowest since pre- depression days , chiefly because numerous idle East Texas plants were removed from the list . The new method of compiling the statistics sheds considerable light on excess crudeoil capacity , which has been the subject of considerable speculation in recent years . The highest daily average crude runs to stills reached in this country was about 3,460,000 barrels in September 1937. At that time , the total crude - oil capacity was about 3,925,000 barrels . This indicates that at peak operation the excess capacity was somewhat less than

Aug 1, 1938

By D. Renda

With thise Process of obtaining a solid fuel which is both ecological clean and has a high calorific value by a two-stage method of enriching preferably type lignitic coals to remove a high content of all sulphurs, incuding organic sulphur, which method comprises converting the coal to a semi-coke from followed by magnetic separation. In the Experiments given the best results the washed lignite coal in the West-Turkey, Tavsanli- Region, size -3.35 mm on dry basis. In the microscopic studies of the brigh-thin cross-section taken from the samples of sulfur min-erals pyrite in the dimension of 2~50 micrometers and melnicovite 10 micrometers particles. An thermal treatment an semi-coking themperature between 370°C to 650°C give the best Result of 480 °C. The oxidation and decomposition of sulphur minerals pyrite and melnicovite in lignite coal proceed the iron oxides Fe2O3 and pyrrhotite FeS on the surface layer. The Magnetic Seperator (Rare Earth Magnetic Separator, REMS) is capable this two form of sulphur, including organic and inorganic sulphur, in semi-coke and resulted in the magnetic-fraction in REMS. The non-magnetic-fraction remove total sulphur by 68 %, ash by 44 % and increase the upper calorific value in 15 %. The clean lignitic coal can be utilized in human or energy power stations.

Jan 1, 2014

By A. B. Campbell

The mines in the eastern part of the now active region of the Tri-State zinc district of Missouri, Kansas, and Oklahoma have unusually acid water, which during periods of moderate or no rainfall As used in the mills to replace losses from evaporation, seepage, and tailings disposal. Its use has caused difficulties by corrosion of equipment and by interference with flotation. The growing importance of flotation- Which requires good water, and the increasing troubles caused by the corrosion of the milling equipment have prompted the Mississippi Valley Experiment Station of the United States Bureau of Mines, in cooperation with the Missouri School of Mines and Metallurgy, Rolla, Mo., to investigate the action of the waters on flotation and to undertake to develop means of obviating their harmful effects.

Jan 1, 1932

By A. K. Fallaw, D. L. Taylor, G. Wang, L. R. Moore, S. Dobson, C. B. Parkinson

"Over the years, the decline of high grade ores have become an increasing problem in the global mining industry. As such, techniques and chemistries must change in order to continue to meet the market demand and quality. Reverse cationic flotation of quartz and silicates is one of the most important techniques for generating the industry standard product from minerals such as iron and phosphate ores. Amine collectors are the global standard in such processes. However, as the ore quality continues to decline so must the chemistry change to meet the change in ore composition. This paper will focus on the introduction and full scale application of a novel amine collector towards a cleaner flotation process in phosphate beneficiation with Crago process. The results suggests the collector is capable of improving the phosphate recovery, in this cleaner circuit, to approximately 94% with minimal sensitivity to the everyday changes in feed grade.INTRODUCTION The days of mining high grade minerals are long gone, but the demand continues to increase. Phosphate ore, for example, is most dominantly demanded from the agriculture industry as a fertilizer component (i.e. diammonium phosphate, DAP) (FAO, 2014). Some literature suggests that global food production must increase by approximately 70% by 2050 (Cordell, 2009). It is also suggested that the peak global phosphorus production will occur around the year 2033, which is the period at which the easily accessible reserves have been depleted. Currently, phosphorus is commonly mined with a BPL (Bone Phosphate of Lime) concentration of 12-20% and a remainder typically being gangue minerals such as silica, clays, metal oxides, calcareous minerals, and carbonaceous minerals. These gangue components can lead to various negative processing and utilization consequences. Calcium, from carbonaceous minerals, is problematic due to the elevated levels of sulfuric acid required to convert the phosphate rock to the acid form (SRI Consulting, 2009). Calcium can also lead to elevated dosages of flotation reagents due to the desire of the fatty acid to coordinate to calcium minerals. Carbonate leads to increased levels of foam during the wet acid process. Silica is associated with the level of insols (acid insolubles), which must be less than 10% in the final concentrate that will be transferred to the chemical plant for acidification. Phosphate ore can generally be classified as carbonaceous or siliceous (El-Shall, 2003). Siliceous ores are commonly processed through various sizing steps followed by multi-staged flotation (Figure 1) (FIPR, 2014 & Güven, 2010). Though the higher grade phosphate pebble is declining, many mines are still able to size good enough to produce some amount of such pebble. Unlike most metal flotation processes where grinding is a necessity for an optimal process, Florida phosphate flotation does not generally require aggressive grinding and can typically operate at 0.1-1.0 mm. The rougher flotation step applies pH modification to achieve the optimal pH of 8.8-9.3 followed by conditioning with a fatty acid type collector, which builds a hydrophobic waxy layer on the surface of the particle to assist in the flotation. This generally achieves higher than 85% recovery of a product with 50-60% BPL and 15-30% insols. Unfortunately, DAP production generally requires 3.5 tons of phosphate rock containing greater than 63% BPL to produce 1 ton of phosphoric acid (ArgusMedia, 2014). Thus, further purification is required to achieve the grade by the chemical plant for fertilizer production. After the fatty acid is scrubbed off the phosphate particles using sulfuric acid (pH 2.5-3.5), the pH is generally operationally readjusted to 6.5-7.2 by washing with “fresh” water. A second collector is applied prior to the cleaner, which is a reverse cationic flotation process. This collector is typically a cationic amine based reagent, which should have an affinity for silica containing mineral"

Jan 1, 2015

By Lloyd A. Morley

Previous research conducted for the USBM by Penn State personnel (Grant GO-101729) found that a need existed to physically model a typical a-c/d-c coal mine section electrical system. Its purpose would be to permit preliminary evaluations of electrical problem solutions prior to launching full-scale investigations. Such use can result in greater flexibility than afforded by present computer models. Furthermore, numerous problems, which would be virtually impossible to incorporate in a computer model at this time, are more easily analyzed with physical simulation. The development of this system is now proceeding at the USBM's Bruceton Research Facilities. However, electrical specifications of scaled down components for its construction are required. This project is a result of that need and has been funded as an extension to Grant GO-133077. The following report covers these specifications. Scope of Work To represent a mined a-c/d-r. coal mine section, the typical component specifications must detail at least: a. one a-c continuous miner, b. two a-c or d-c shuttle cars, c. one a-c or d-c roof bolter, d. one a-c section fan, and e. feeder cables. Further, each machine should be portrayed by each of its general

Jan 1, 1974

By Ruirui Wei, Mingrui Yang, Xuewei Lv

Copper slag is a by-product obtained during smelting of copper from copper ores. In China, for one ton of metal production about 2.2 tons of copper slag was generated, and approximately 15 million tons slag is produced in 2013. Dumping and disposal of such huge quantities of slag will cause environmental and space problems. Most importantly, copper slag cannot be made full use of to maximize its value. In this study, copper slag was used to take the place of scrap iron and part of silica in traditional process and to produce FeSi alloy as the main material. Utilizing silica and copper slag as the raw materials and coke as the reducing agent, FeSi45 was produced in the induction furnace. In addition, the effect of different n(C)/n(O) on FeSi45 has been investigated.Increasing n(C)/n(O) is beneficial to form the stable phase of FeSi. Meanwhile, n(C)/n(O) greatly affects the reduction and recovery of silicon than iron. When n(C)/n(O) equals 1.10, the recovery of silicon and iron is about 77 and 95%, respectively.

Mar 1, 2017

By P Esteves, J L. Bechir, R Galery, C Senna, V Souto

The current moment experienced by the mineral industry is marked by a series of economic, social and environmental challenges. Among the main challenges, it is important to highlight the decreasing in ore grades with the gradual depletion of the existing deposits, the high volatility in international commodity prices and the operational inefficiencies in the mine, beneficiation, and metallurgical plants. In this context, mining companies are continuously looking for alternatives that minimize production costs and maximize overall production. In addition, recent tragedies involving tailings dam collapses in Brazil, reinforced the need for a more responsible, sustainable, and conscious mining, such as aiming the preservation and rehabilitation of the land environment. In this scenario, the Sensor-Based Sorting (SBS) technology is currently getting more space into the mining market. This separation technology aims the removal of gangue material in coarse particle size fractions, prior to comminution and concentration stages. As a consequence, the technology allows a smaller consumption of energy, water, chemical reagents and other inputs. Moreover, the sensor-based sorting is a dry processing technology and favors the reduction of fine material to be sent to the tailings. The aim of this paper is to provide information regarding the technical and economical evaluation of SBS technology applicability to a zinc silicate mining in Brazil. The project evaluation was performed in two stages: laboratory test work and the execution of a pilot plant. The execution of a pilot plant allowed the technology optimization, quantification of downstream process effects, such as a proper economic evaluation about the technology benefits. Keywords: Sensor-Based Sorting; Particle Sorting; Ore Sorting; Preconcentration; capital expenditure (CAPEX); operating expenditure (OPEX); zinc; comminution; dry processing.

Nov 10, 2020

The Malvern Hills coal project is now in an advanced stage of development with the stripping of overburden from above former underground workings in which a 3 m seam of subbituminous C coal with very low ash and sulphur was previously mined. The main seam dips at 45¦ to the south-east, along with other adjacent potentially recoverable thinner seams, and the strike extent of past coal mining in the Malvern Hills approaches 10 km with most extraction by underground methods. Overburden and interburden is predominantly weak mudstone, with only very minor sandstone, whilst a 1 - 2 m thick veneer of Last Glaciation loess covers the area. The coal product from the present mine site will supply the local industrial market, with production planned to peak at about 20 000 tpa. Settling pond design has been based on several different approaches, including an estimate of likely inflows from the contributing catchment of about 5 ha under predicted storms having a ten year recurrence interval. A pond of about 1000 m2 in area has been constructed with its invert in mudstone bedrock, and soil slopes have been lined with lime-stabilised clayey loess silt incorporating a gravel armour layer. The pond outflow takes place via a 2 m high 1.8 m diameter concrete dewatering tower, with a skimmer arrangement to lower the pond by approximately 500 mm between storm events. The overflow water discharges to the main stream above a natural wetland, which will act as a secondary polishing pond, and this is to be enhanced in conjunction with the neighbouring forestry company. Discharge consents specify turbidity and pH as the controlling criteria, and both will be monitored at the settling pond discharge point as well as at the entry to the main stream. Investigations to date indicate that the pH of water exiting from previous underground workings is in the range 6.8 to 7.2, and that acidic drainage will not be an issue with this mine site. No dispersive clays have been identified in assessing the overburden and batter materials, although erosion during storm events is expected and all drains will ultimately be routed through the main settling pond to ensure adequate control of runoff-generated sediment. Reestablishment of vegetation on cut and fill batters remains a priority, and ongoing monitoring will ensure satisfactory long-term performance of the pond system.

Jan 1, 2003