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By S. K. Utimurd, D. C. R. Espinosa, J. A. S. Tenório

"Waste Electrical and Electronic Equipment (WEEE) has become an environmental issue due to technological advance and waste plastic is one of the main polluters. The excessive discard of these plastics result in a difficult to dispose it to landfill and need further separation with technique in order to produce high added value plastics. There are many kinds of plastics in extensive use at the present time and the co=on are the acrylonitrile-butadiene-styrene (ABS) and high impact polystyrene (HIPS) used in the production of electric appliances. These plastics are difficult to separate because they have similar densities. Flotation of plastics is one possible separation technique and using selective wetting agents. The separation may be possible given close control at particle size and the concentration of the reagent. The process was able to produce a concentrate of HIPS with at least of 93% purity and a concentrate of ABS with 99% purity.IntroductionThe current situation of municipal solid waste (MSW) management especially in emerging economies like Brazil, the growing population and economic activity will result in a significant increase in the generation of waste in the coming decades. It is worthwhile to review and update the sources, amounts and recovery technologies of specific materials from waste, particularly from municipal solid waste (MSW).The growing impact of the current waste management practices stresses the need for a change in how waste is handled. The 2012 survey and the Brazilian Association of Public Cleaning and Special Waste Disposal Companies (ABRELPE) reports the generation of 62 Mt urban MSW in that year, which is an increase of 13% compared to 2011. It has been reported that in Brazil about 90.17% of the generated MSW is currently collected, which indicates an increase in the coverage of collection services compared to 2011 [ l]."

Jan 1, 2014

By I. L. Nichols

Volatilization of cesium from pollucite ore was investigated as an initial step in the production of purified cesium metal or cesium salts. High recovery of cesium and rubidium as chloride sublimates was accomplished by 2-hour roasts in a tube furnace using charges containing 1 part ore, 2 parts limestone, and 0.23 part calcium chloride. Recoveries of cesium in the sublimate product were 89.1, 92.9, and 95.2 pct, respectively, using 1,100° C and vacuum, 1,250° C with an air sweep, and 1,250° C without an air sweep. Most of the lithium, sodium, and potassium sublimed with the cesium and rubidium, but virtually none of the calcium, aluminum, and silicon in the charges was volatilized.

Jan 1, 1966

The effect of addition of a flotation collector (dodecylammonium chloride) on grinding of quartz has been studied. The data obtained are correlated with the results of tests conducted under similar chemical conditions to study influence of these additives on relevant basic sub-processes (primary breakage, pulp fluidity, and dispersion and flocculation of ground products). Such correlations suggest that the role of chemical additives in grinding is determined by their cumulative influence on the above mentioned basic properties of the system.

Jan 1, 1982

By S C. Dominy

The gravity recoverable gold (GRG) parameter reflects liberated gold or gold-dominated composite particles that can be recovered by gravity separation. Recoveries depend upon mineralogy, in situ particle size and the comminution and extraction method used. Any ore bearing >15 per cent of gold greater than 50 ¦m in size is likely to have a GRG component. The principal characterisation methodology applied is the three-stage GRG (3GRG) test, based on a 40 kg to 100 kg sample. An alternative is the single-stage GRG test (SGRG), which is generally based on a 20 kg sample. Experience has shown that GRG values can vary throughout an orebody, particularly within different grade and/or mineralogical domains. Test programs must consider sample frequency and mass. This study demonstrates the variability of GRG results based on different sample masses. Consecutive underground faces on a coarse-gold dominated quartz vein were sampled taking five different masses from each. Each sample was processed using a SGRG approach. Subsequently, each development round was batched through a small gravity production plant. The results show that the small samples understate the plant GRG and show inter-sample variability. Large samples show less variability and a SGRG closer to the plant GRG. A high SGRG broadly correlates to higher gold grades, more coarse gold and larger gold particles. These results are intuitively correct, but indicate the likely challenges of sampling for gold recovery in heterogeneous systems.CITATION:Dominy, S C, 2013. Variability of gravity recoverable gold values in relation to test sample size, in Proceedings The Second AusIMM International Geometallurgy Conference (GeoMet) 2013 , pp 293-302 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 29, 2013

By J. P. Bennett

The Bureau of Mines is investigating the acid resistance of ceramic materials to identify construction materials for emerging technology in chemical and metallurgical processes. Eight commercial ceramic materials, including two red shale, two fireclay, a silica, a silicon carbide, a carbon, and a high-alumina brick, were evaluated. Samples were exposed to 40 wt pct HN03 at 70° and 90° C and 60 wt pct HN03 at 50°, 70°, and 90° C for time periods of 110 days. Statistically significant changes in cold crushing strength were generally small or not detected, except for a strength drop in the high-alumina brick, which decreased in strength when exposed to the chosen acid concentrations at 90° C. Vol-ume and weight changes were also measured. The leach rates of Al, Ca, Fe, K, Mg, Na, Si, and Ti were monitored. Increasing temperature or a decrease in the acid concentration resulted in an increased ion leach rate. Of the conditions tested, the most severe corrosion occurred at 90° C for a 40-wt-pct-HN03 solution. The silica brick had the best overall acid-resistant properties, followed by a red shale and a fire-clay brick. The carbon and silicon carbide bricks are not recommended for service.

Jan 1, 1984

By A. Rosenfeld

The feasibility of applying laser induced optical emission spectroscopy to the high speed sorting of mixed alloy aluminum scrap is investigated. The basic spectroscopy for analysing aluminum alloys for the major alloying elements over their full concentration ranges is established. Materials handling issues are also described and the components of an overall sorting system are presented.

Jan 1, 1995

By John B. Miles

THE present period of depression in the iron industry, with the resultant close approximation of the cost of production to the selling-price of pig-iron, should make the discussion of this subject at this time not only interesting but, profitable. It is possible that it may result, in the collection of data, which when added to those set forth in this paper will clearly indicate the influence of the rate. of driving a blast-furnace upon its fuel-economy. The question is not whether an excessive rate of driving (meaning a rate definitely in excess of the average rate in the United States) results in, an increase in the fuel-consumption, but rather whether a rate considerably less than the average does not result in a marked decrease in the fuel-consumption. The commercial and metallurgical sides of. this problem must be kept separate. With a large margin between the cost of production and the selling-price of pig-iron, and a plant already in operation, it is frequently profitable to sacrifice a couple of hundred pounds of fuel per ton of pig-iron in order to secure the greater gross profits resulting from a larger tonnage. When this margin decreases with a plant in operation, or when the determination of the size of a new furnace intended for a certain production . confronts the management, a clear understanding of the effect of the rate of driving upon fuel-economy becomes necessary. If it be granted that slow driving leads to low fuel-consumption, it should he borne in mind in the design of a new plant for the production of a certain tonnage that the adoption of an economical rate of driving increases only the size of the furnace proper, whereas, due to the decrease in quantity of blast required on account of the decrease in fuel burned, the stoves, the blowing-engines, the boilers and the piping may be de-

Sep 1, 1908

By A. Hayatdavoudi, K. G. Sawant, F. Boukadi

"In this work, we found that contact between shale and water results in development of micro fractures. Based on results of experiments on Pierre shale, we conclude that appearance of micro fractures begin with saturation of capillaries, ionic and diffusive transport of water into the shale clays and once capillaries are saturated, the cause of micro fracture propagation is the conversion of ionic activity/exchange to excess pressure that did not exist before fracking. Based on these findings, the spread of micro fractures appear to be a time-dependent phenomenon which has not been addressed in the existing macro/micro fracture models.INTRODUCTIONShale has often been involved as a hazard in drilling operations. This hazard can be defined as “destabilization” of shale. When contacted with water-based drilling fluids, some shales readily swell and sometimes, cause the wellbore to cave-in, slough, wash-out, close, and pack-off, impeding the drilling by sticking the drill-pipe. However, once drilling reaches the desired depth or length, the casing is set, cemented, and perforated, and then actually we wish to initiate fractures and destabilize the shale formation, using hydraulic fracturing.Clays constitute a major portion of minerals in shale. These clays contain a large amount of free energy which is the main factor for “slick” water adsorption/absorption. In fact, the reason for using “surfactants” in hydraulic fracturing fluids is to make the penetration of the fluid into the capillaries much easier, thus water meets with less resistance to enter the small capillaries. Also, the result of high capillary suction pressure is due to small Angstrom size capillaries, smaller pores and presence of ions and hydrateable metal atoms. The free energy is thus, related to all the above mentioned and other affects. Capillary pressure, osmotic pressure and other pressures are responsible for creating the micro-fractures in shale, thus, increasing the network of micro-fractures which leads to more gas production. The objective of this study is to evaluate the pressures of the individual ions which are released by the diffusing “slick” water into shale. These pressures would be added to the above mentioned capillary pressure, osmotic pressure, bacterially-induced pressures, chemically-induced reaction pressure, pressure due to exchangeable ion-transport, pressure due to release of free energy of solvation and eventually to the pore pressure as suggested by Terzaghi’s equation."

Jan 1, 2015

By Maurice Guillaud

The most striking innovations on diaphragm-wall construction plant are those associated with continuous real-time trajectory monitoring of the excavating tool (either a grab or a hydro-cutter). The recent equipments are fitted with clinometers and gyrometers to control deflection, rotation or deviation from the vertical, thus allowing to install diaphragm-walls with a verticality accuracy of less than 0.3%. One of the greatest advantages of extensive use of on-board IT systems on the Hydrocutters and hydraulic grab machines is that it aids quality control by automatically producing complete real-time reports of all excavating data (verticality, depth, type of ground, rate of progress, stoppages, etc.). These reports are available to the Engineer, providing the total transparency required for Works Supervision and the Quality Assurance Plan. They also provide the Contractor with input data for databases used for optimising efficiency and progress criteria on future jobs.

Jan 1, 2002

By D. R. Pyke

Many of the gold deposits in the Timmins• area show a close spatial association to ultramafic metavolcanics. Available analytical data suggest that ultramafic rocks contain significantly higher gold contents than other major rock types. In addition, recent analyses by Keays (1975) suggest that talc-carbonate alteration of ultramafic rocks releases significant quantities of gold. It is proposed that the ultramafic volcanics formed the principal source of gold for the deposits in Timmins, and that the gold was derived from the ultramafic flows when they were extensively carbonatized. Carbonatization of the ultramafic rocks and emplacement of the auriferous quartz-carbonate veins was probably coincident with the last major period of deformation in the gold camp. Delineation of hitherto unrecognized ultramafic volcanics could be an important guide to the discovery of further gold deposits.

Jan 1, 1976

By J. C. Swartz

Measurements of the effect of precipitation stresses on the solubility of cementite (Fe3C) precipitates in a iron are reported. Solubilities were determined from measurements of the Snoek relaxation due to interstitial carbon after quenching from various equilibrium treatments. Stress-free precipitates were obtained by a spheroidizing treatment of vacuum-melted Fe 0.06 wt pet C. Subsequent equilibration treatments were designed to suppress nucleation of other precipitates. The results for stress-free cementite give a heat of solution of 14.8 i 0.2 keal per mole and an entropy change of 1.1 i 0.2 eu in the temperature range 400" to 715°C. Comparison with previous data indicates that the heat of solution increases about 6 keal per mole as temperature increases from 700" to 1000°C. Data on self-stressed cementite in quench-aged specimens of Fe 0.013 wt pet C indicate 1) an apparent heat of solution of 12.1 i 0.4 keal per mole in the range 280" to 690°C, 2) a strain energy of- 1.1 keal per mole Fe3C accompanying precipitation at 280°C, and 3') a gradual decrease in the strain energy of precipitation with increasing equilibration temperature. In com-parison with 2 and 3 the strain energy calculated for an isotropic model is 1.7 keal per mole Fe3C. The lower values obtained from the experiment indicated substantial stress velaxation by dislocation motion. WHEN a supersaturated solution of carbon in a iron is aged at temperatures in the range 200o to 700oC, the carbon clusters by interstitial diffusion and forms cementite (Fe3C) precipitate particles. Unstressed cementite has a volume per iron atom 9 pet higher than that of a iron;' hence, cementite precipitate particles are usually under pressure from the iron matrix. The pressure would tend to increase the solubility of cementite in iron.' This report describes anelastic measurements of the solubilities of self-stressed and stress-free cementite in a iron. Previous determinations of the cementite solubility are summarized in Table I. The method of cementite formation for each reference was studied to ascertain the state of stress of the cementite. The results judged to be for stress-free and stressed cementite are distinguished in the table. In the next section an estimate of the stress effect is obtained which is clearly too small to account for the large difference between the previous results in parts A and B of the table. THEORETICAL Let AGO be the standard free-energy change of the reaction Fe3C (eem.) = 3Fe (a) + C (in a) [1] in the absence of stresses. Since cementite precipitates appear to be rather pure10 and the carbon is so dilute in the iron,8 the cementite and iron of Eq. [ I] for the stress-free case have essentially unit activities and the activity of carbon equals its atom fraction xoC Then the stress-free equilibrium is expressed by RT In XoC = -?GO 121 To first approximation the change in the chemical potential of carbon due to the precipitation stresses equals the elastic strain energy W accompanying precipitation of a mole of cementite.2 Hence, in the presence of the precipitation stresses the equilibrium is described by RT In x sq = -?G° + W [3] where xsC is the mole fraction of dissolved carbon in the stressed case. An approximate value of W can be obtained from analysis of the inclusion problem in elasticity theory. The inclusion is a small portion of the matrix phase which has suffered a transformation while still imbedded in the matrix. In the absence of the constraint of the matrix the transformation would be equivalent to a uniform dilational strain eT. Both the matrix (a) phase and inclusion (0) phase are assumed to be homogeneous, isotropic materials. When the a and 0 phases have the same elastic moduli, which is approximately true for iron and cementite,11 the total strain energy per mole ß is12 2µVß(eT)2(3 +4 µx)-I [4]

Jan 1, 1968

By A. G. Waters, N. J. Bristow

A comparative study was made of an untreated and a heated haematite ore and a sinter produced from a feed consisting of 100% ore, to study the influence on reduction behaviour of sinter bonding phases such as SFCA (silico-ferrite of calcium and alumina). Under low-temperature reduction conditions the order of increasing reducibility followed that of increasing porosity and surface area but under similar conditions at 900 degrees C the sinter exhibited higher reducibility than the ores even though the total porosity and chemical reducibility of the individual phases were lower. This behaviour can be explained in terms of the higher total porosity of the natural ore at low temperatures and the higher level of fine pores in the sinter at high temperatures due to the presence of SFCA, which acts to support the fine (c.0.1 micrometre) pores created by the reduction process. This leads to the conclusion that the main role of SFCA in sinter during high-temperature reduction is to maintain a high level of fine porosity. Some implications of this work for granule design and sintering practice are discussed

Apr 1, 1991

By Sharpe E. J

The Triton lode is a schistose feldspar biotite chlorite rock with quartz, carbonate, pyrite and some pyrrhotite. Its more chloritic sections strongly resemble the enclosing greenstones, its more feldspathic portions are indistinguishable from the flne-grained phases of the porphyry dyke into which the southern extremity of the ore body merges. The ore body' has a length of 880 ft. and an average width of I2t ft.; in places this widens to as much as 30 ft.The average dip is 85° west and pitch of the ore shoot 75° south.METHOD OF SAMPLING.With the exception of a limited amount of channel sampling (a reference to which is made elsewhere in this paper) all the sampling is by chip sample.The samplers use a hammer weighing approximately 11 lb. and chip directly into the sample bags. Sampling is generally carried out over 3-ft. sections and portions thereof to the nearest half foot-thus a face 8t ft. wide is divided up into two sections of 3 ft. each and one section of 2 ft.-no measurements of less than 4 ft. are used and calculations are all in feet and dwt. per long ton.In the oxidised stopes wp.ere the lode is much narrower, .i.e., 6 ft., sampling is over 2-ft. sections. All borehole samples are over 2-ft. sections, this corresponding approximately to steel changes.(a) DEVELOPMENT SAMPLING.Driving.-This is done by following the east wall and each face is sampled-this corresponding to an advance of 5 ft. If the full width o,f the lode is not exposed boreholes...

Jan 1, 1938

By Zachary Q. Maassen

Upon approval from the Las Vegas Convention and Visitors Authority (LVCVA), Turner/Martin Harris, A Joint Venture began construction on the estimated $860 million expansion for the Las Vegas Convention Center District Plan. Totaling around 600 shafts (60 feet depth and 3-foot diameter), the foundation installation completed via uncased drilled shaft operation, spanned from October to December of 2018. During this installation, flowback water from the water table was encountered that contained various solids ranging from cobbles to clays to silts, as well as trace amounts of contaminants of concern (COCs) left behind as a result of previous business that used to occupy the same real estate as the current expansion; more specifically, Perchloroethylene (PCE), an organic chemical widely used as a solvent and degreaser. With over 2.5 million gallons of waste slurry to be treated, technologies were deployed to reclassify the waste from liquid to solid waste as well as recover and treat the water for reuse in land spraying applications. Utilizing these technologies, it is estimated that 1.2 million gallons of water was able to be reclaimed along with over 6,400 tons of solids; resulting in hundreds of thousands of dollars in cost and environmental savings. PROJECT OVERVIEW Amidst its famous attractions from gambling to world class entertainment, Las Vegas has long been highlighted as the “No. 1 trade show destination in North America for 24 consecutive years” (LVCVA, 2018). Each year, Las Vegas hosts approximately 22,000 meetings, conventions and trade shows, which support an estimated 65,000 jobs paying $2.7 billion in wages and salaries. In 2017, the Las Vegas Convention Center hosted 21 percent of convention attendees traveling to southern Nevada, which supported approximately 13,800 jobs, paying more than $576 million in wages and salaries. Including indirect and induced impacts, the Las Vegas Convention Center’s attendees generated $2.1 billion in economic impact for the local economy (LVCVA, 2018) . This substantial economic impact of course due in part to the attractions Las Vegas offers to its trade show attendees, along with Las Vegas’ easy accessibility to major metropolises along the West Coast and reasonable travel prices offered if coming in from the East, allows for a very attractive venue. And while being a famous destination is great for business, the city wants to further distinguish itself by offering the best venue as well. For this reason, the Las Vegas Convention and Visitors Authority (LVCVA) approved a three-phase expansion plan for the Las Vegas Convention Center District totaling well over a billion dollars, slated for completion by 2023.

Jan 1, 2019

By S R. Grano

The selection of the proper frother, specifically for a given ore, is essential in flotation. Traditionally, strong and stable froths are required in the scavengers, where metal recovery needs to be maximised, while selectivity must be achieved in the roughers and cleaners, where grade of concentrates is the main issue. The physical properties of a froth are determined both by frother type, by process water composition and by the amount and nature of the suspended particles. The evaluation of different frothers, in terms of metallurgical performance, is complicated at plant scale, since it may lead to periods of malfunctioning of the process and unacceptable decreases in recovery. On the other hand, evaluation based on frother chemistry only, is often unsatisfactory, because the frothing response is strongly ore dependent. A procedure, and proper tools, was developed at the Wark in order to perform the screening of candidate frothers at batch scale on real pulp samples. The main parameters related to froth stability (half-life time, froth height) are measured after introducing the pulp samples into a foaming column, where different conditions in terms of frother addition, agitation and aeration can be maintained. The approach has been applied to the selection of frothers for the flotation of an Australian sulfide ore. Procedure and results are discussed.

Jan 1, 2006

During heap leaching of secondary copper sulphide ores operated at low heap temperatures and high levels of leach solution salinity, copper recovery is usually unsatisfactory, due to a slow chemical and bacteriological leaching of the covellite minerals either formed from leaching of chalcocite or naturally occurring in ores. A laboratory test program was conducted to investigate the effect of leach solution temperature in the range of 20 to 50°C on copper extraction during stirred reactor, bottle roll, and short column leaching of fresh or heap leached secondary copper sulphide ores. It was demonstrated that increasing heap temperature is an effective approach for improving recovery of copper from secondary copper sulphide ores. A review of the technologies available for heating heap leach solution or decreasing solution salinity to improve copper recovery from secondary sulphide ore indicates that an integration of copper concentrate pressure leaching with heap leaching is potentially a cost-effective approach. A copper flotation concentrate sample was tested through pressure oxidation with the use of heap leach solutions of varying strengths for the repulping of the concentrate in order to examine its effect on pressure oxidation performance. The test results indicate that use of heap leach solution of high salinity in the pressure oxidation process does not cause a negative impact on the process performance for copper extraction, sulphide oxidation, and recovery of gold (if present) from pressure leach residue, and has additional advantages of removing the bacterially inhibitory aluminum from heap leach solution and generating more acid and ferric iron in the pregnant leach solution. A flowsheet configuration for full integration of the copper concentrate pressure oxidation with heap leaching of secondary copper sulphide ore is proposed and discussed.

Jan 1, 2014

By R. A. Guidotti

The Federal Bureau of Mines studied the thermal decomposition of the nitrides of the Group V A metals (CbN, Ta3N5, and VN) with the goal of preparing high-purity metals. Solid-state purification and arc and electron-beam melting were examined. Electron-beam melting proved to be the most efficient means of nitrogen and oxygen removal. Columbium and tantalum of 99.9-pct purity were prepared by this technique; in the case of vanadium, however, nitrogen could not be reduced below the solid-solution level.

Jan 1, 1976

By Steve T. Laflin

Since the beginning of the nuclear era, there has never been a commercial solution for the large quantities of depleted uranium hexafluoride generated from uranium enrichment. In the United States alone, there is already in excess of 1.6 billion pounds of DUF6 currently stored. INIS is constructing a commercial uranium processing and fluorine extraction facility. The INIS facility will convert depleted uranium hexafluoride and use it as feed material for the patented Fluorine Extraction Process to produce high purity fluoride gases and anhydrous hydrofluoric acid. The project will provide an environmentally friendly and commercially viable solution for DUF6 tails management.

Aug 1, 2010

By R. Venkataramani

Crushed stone operations have become more difficult due to rising costs of labor and equipment, with the consequent reduction in profit margins. Competition from other operators and the encroachment of vertically integrated companies place severe restrictions on available markets. The seasonal demand for stone precludes any definite production level, and changes in productivity have to be accommodated. These influence profitability, and therefore production plans must be continuously adjusted to keep pace with rapidly changing conditions. The basic problem of stone companies seeking to maximize profits is one of balancing stone production costs, costs of inventory holding and stock-piling, marketing costs and any other charges accruing over time against the selling price of stone. Because of high peak demands, slack period production must be stored and then distributed to supplement peak period production. For a multi-plant operation, there is a need to evaluate at the same time the interaction between the plants and the various marketing sectors. In a multi-plant operation with different production capacities and production costs, stone producers are interested in the answers to the following questions: 1. How much stone should be produced at each plant in each time period? 2. What should be the optimum stone shipment from each plant to each market? 3. What are the effects on net returns and shipping plans, if production capacities are altered at the plants? These questions have many different answers that, will satisfy demands. From the point of production scheduling, the minimum production cost may be the objective. From the inventory standpoint, the best solution will be to synchronize production with sales. However, when the transportation of stone is also considered, the desired end is to achieve that delivered cost which maximizes the company f s net return. Besides, only an extremely naive analysis ,wouId attempt to

Jan 1, 1971

By George W. Pawel

OWING largely to its value as a toughener and strengthener of steel for both industrial and military purposes, nickel is playing, an important role in the current war. It is fine of the metals in which the Allies enjoy a definite edge over the Axis nations and this time there is no place to which the Germans may send another submarine "Deutsehland" and expect to pick up a cargo of nickel to replenish their exhausted supplies. Total world nickel production thanks almost entirely to the expanded operation of the International Nickel Co. of Canada at Sudbury must now be at the rate of around 175,000 tons a year scarcely more than 5 per cent of which is accounted for by Germany, Italy and Japan. This represents more than four times the world output at the end of the first World War.

Jan 1, 1943