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By Robert H. Leach, C. H. Chatfield

THIS paper gives a brief summary of the process of manufacture of sterling silver, and some of its more important physical properties, as observed in commercial production of rolled sheet and wire. Although papers have been published by Turner and Smith,1 Rose,2 Sperry3 and Jordan,4 there are few technical data available, and unfortunately the time allowed for the preparation of this paper has not been sufficient to make it as comprehensive as the title might indicate. ANALYSIS OF STERLING SILVER Fine or pure silver is too soft for coinage and the manufacture of articles in which strength and resistance to wear are desired. From the earliest times of which we have record, copper has been the metal generally used to harden silver. Analyses of coins and silver articles from ancient tombs show varying amounts of copper, and old Roman silver objects in the British Museum have approximately the same analysis as our sterling. The first authentic record of the establishment of a stand¬ard alloy is during the reign of Henry II in England. During the twelfth and thirteenth centuries, the people in the Eastern Provinces of Germany had a reputation for the standard and purity of their silver coinage, and it is said that Henry II employed some of these Easterlings, as they were called, to improve and standardize the English coinage, which had become debased. The peculiar standard adopted is probably accounted for by the system of weights used. A troy pound contains

Jan 1, 1928

By J. M. Somers

Methane is a powerful greenhouse gas and the principal component of natural gas. Coal seams often contain significant quantities of methane, and underground coal mines must ensure that methane released into the mine during coal extraction does not build to dangerous levels. This is accomplished in part through the use of large-volume ventilation systems that remove methane from the mine and release it to the atmosphere. Although the methane concentration exhausted is quite low (typically <1 percent), the volume of air that ventilation systems move is so great that they actually constitute the largest source of methane emissions from underground coal mines. Each year underground coal mines throughout the world emit more than 500 billion cubic feet of methane from their ventilation systems. An air pollution control technology, thermal oxidation using a flow-reversal reactor (TFRR), has emerged as a potential solution to ventilation air methane (VAM) emission mitigation. One manufacturer of TFRRs has demonstrated its oxidizer design (the VOCSIDIZER?) at coal mines in the United Kingdom and Australia. These demonstrations tested the technology?s effectiveness at oxidizing low-concentration methane, as well as its ability to tap the excess heat to produce steam for electric power generation. In early 2007, the first U.S. demonstration of this technology began operation at an abandoned mine in West Virginia. The project is designed to prove the technology?s operational robustness, its ability to reliably oxidize methane at concentrations typical of mine exhausts, and its safety. If the technology is employed at active underground coal mines, it offers the potential to mitigate substantial quantities of global methane emissions. This paper discusses global VAM emissions, options for the recovery and utilization of VAM, and existing projects such as WestVAMP in Australia and the ongoing U.S. VAM demonstration project.

Jan 1, 2009

By L. C. IlsLey

The increasing use of Diesel engines for operating equipment on trunk-line railroads and for power-plant units has stimulated interest in the use of Diesel engines for other lines of work, among which is the possibility of substituting Diesel locomotives for trolley locomotives for mines. The possibility of developing Diesel locomotives for duty in American mines is not as remote as it might seem, particularly in view of the fact that locomotives of this type are already used in considerable numbers in European mines. A study of Diesel locomotives in Europe is contained in Report of Investigations 3320, Diesel Mine Locomotives - Development and Use in European Coal Mines, by George S. Rice and F. E. Harris.

Jan 1, 1938

By R. A. Cattell

The peacetime activities of the Bureau&apos;s petroleum and natural-gas program have been reoriented to serve the needs of a national-defense program. When the United Nations sent troops to Korea after the North Korean Army crossed the 38th parallel in the latter part of June 1950, the Bureau&apos;s coordinated national program on petroleum and natural gas, with each major project forming an essential member of its framework, was carefully reviewed by those in charge of the work. As a matter of fact, the era of normalcy in which the petroleum and natural-gas research of the Bureau of Mines prospered during the fiscal year 19502/ was no sedative to the need for alertness on a national-defense front. The program, although conducted along peacetime lines in general, was scanned critically and repeatedly during that period to see where - if the need should arise -the emphasis could be shifted from peace to defense or war. Judging from the experience of two wars, it would not be long before the Bureau would be asked to use its trained technical personnel in applying techniques already learned in peacetime research to the requirements of munition and fuel needs of national defense. Near the end of January 1951, petroleum and natural-gas engineers of the Bureau of Mines began a comprehensive study of reservoir conditions in the Canyon Reef fields of Scurry, Borden, and Kent Counties, Tex. This work was preceded by published analyses of crude oils from Scurry County as early as April 1950. Well-informed persons in industry have estimated that these fields hold reserves that will yield 3 to 6 billion barrels of stock-tank oil. Although generally accepted good operating practices have been followed, engineering tests have shown that the natural energy, except in some favorable parts of the reservoir, will not be adequate for obtaining a high percentage of recovery. Correct information regarding the extent and availability of this vast reservoir of hydrocarbons is therefore of great concern to the Petroleum Administration for Defense in carrying out its responsibilities under the Defense Production Act.

Jan 1, 1952

By Larry Stearns, Lori Tiefenthaler

Remediation of contaminated soil represents a significant market for application of Deep Soil Mixing (DSM). Eighty-one percent of U.S. Environmental Protection Agency (EPA) Superfund Program’s site remedies have involved contaminated soil. Contaminated soil is frequently treated by In-situ Solidification/Stabilization (ISS). ISS treatment of contaminated soil involves mixing binding agents into soil using DSM techniques. DSM is a core business for many DFI members. Members may improve and broaden their services to clients by learning about the recent ISS treatment of contaminated soil at a Superfund site. ISS treatment is part of the EPA-selected remedy for a Superfund Site in the metro New York City area. The property has seen heavy industrial use for more than a century. Soil at the site is contaminated with a variety of volatile organic compounds (VOCs), polycyclic aromatic hydrocarbons (PAHs) including coal tars and heavy metals, principally arsenic and lead. Beginning in 2017 and continuing through 2018, approximately 150,000 cubic yards (115,000 cubic meters) of soil will be treated by ISS at the case study site. Portland cement and slag cement are mixed into the soil by DSM techniques using GPS guided excavators to immobilize the hazardous constituents within the treated soil. ISS treatment by DSM will contribute to redevelopment of this valuable property. This paper will describe ISS constructability and performance, case study grout mix design with geotechnical results for strength and permeability, and deep soil mixing techniques. INTRODUCTION In-situ solidification and stabilization (ISS) is a deep soil mixing (DSM) technique applied in the environmental remediation field to physically encapsulate, or chemically bind, contaminates of concern such that the impacts to human health and the environment are mitigated. Common remediation applications of ISS include mixing cementitious reagents into contaminated soils to form a monolithic mass with desired performance characteristics, and the installation of vertical subsurface walls designed to control groundwater movement. A key characteristic of ISS is that the contaminated soils are treated in their existing location at the project site and then are left in place after treatment. Typical performance characteristics of the ISS treated soils include improved unconfined compressive strength (UCS), reduced hydraulic conductivity (HC), and reduced leaching potential of soil contaminants. Increased shear resistance of the treated soil may also be a performance requirement where seismic loading is a concern.

Jan 1, 2018

By Gaudin. A. M., S. C. Sun

THIS paper presents the results of a study of the relationship of the electrokinetic or zeta potential to flotation phenomena. The relationship is established on the experimental evidence that mineral behavior in flotation and in cataphoresis is generally governed by the chemical properties and amount of the reagents adsorbed at mineral surfaces. Cataphoresis1-5 or electrophoresis is the name given to the movement of a charged particle in a liquid medium under the influence of an applied electric field. Mineral behavior in cataphoresis, as indicated by the magnitude and sign of its ionic charge, can be represented by the term zeta potential. In this paper, the zeta potential represents the difference in potential between the immovable liquid layer attached to the surface of a solid particle and the movable liquid layer in the body of the liquid, and is the result of the tendency of ions on the surface of the particle and within the liquid boundary layer to establish a condition of equilibrium. A high positive zeta potential means that the mineral surface is dominated by cations, a high negative zeta potential indicates domination by anions, and a low zeta potential indicates that the surface is influenced almost equally by cations and anions. In terms of observed quantities the zeta potential is given by the relation [z = 47ruu(300)$ Kx] in which z is the zeta potential expressed in in volts, u the viscosity of the solution in poises, u the velocity of particles in centimeters per second, x the impressed potential gradient in volts per centimeter, and k the dielectric constant of the solution in c.g.s. units. A convenient source for the derivation of the equation is the book by Thomas,6 The term zeta coefficient is an expression coined to denote the difference between the magnitude of the zeta potential of a mineral suspended in solution A, and that of the same mineral suspended in solution B, which consists of solution A and an additional chemical agent, but is at the same pH. For example, the difference between the zeta potential of galena particles in distilled water and that in any chemical solution at the same pH is a zeta coefficient. Or, when the zeta potential of a mineral particle is measured first in distilled water, then in a mixture of water and copper sulphate, and finally in a mix-

Jan 1, 1946

By J. C. Engel

Recent innovations in mine safety include the use of mercury vapor lamps for mine vehicle illumination. Such lamps, however, extinguish whenever the line voltage at the machine momentarily sags or is interrupted. The lamps must then cool for several minutes before they will restart. By supplying reduced high frequency power to the lamps from an auxiliary source, it is possible to maintain ionization in the arc tubes preventing the lamps from extinguishing. Essentially an auxiliary high frequency supply, the keep alive system provides additional power to the lamps automatically whenever the lamps are in danger of dropping out. The system can also provide the operator with the ability to dim the lamps at will for periods of up to three minutes by simply interrupting the 60 Hz power to the conventional ballasts. Each unit, housed in a steel explosion proof enclosure with a volume of approximately 0.6 ft3, is capable of servicing up to six 175 watt H-39 mercury lamps and two 100 watt H-75 reflector flood lamps. A total of 16 units were produced for the USBM under this contract and its extension.

Jan 1, 1979

By W. C. Babcock

This report covers Phase V of .a continuing program to apply a new liquid membrane process called coupled transport to the recovery pf metals from hydrometallurgical leach solutions. During this phase of the program, a membrane system of moderate scale was constructed and field-tested at the Exxon Highlands Mine and Mill Co. site near Douglas, Wyoming. The test unit contained four hollow-fiber membrane modules, each with 100 ft2 of membrane area. In the field tests, about 1000 gallons per day of leach solution was processed. The unit was operated on the leach solution for about 50 days. Leach solution entering the unit contained 100 ppm uranium. This concentration was reduced to about 5 ppm by coupled-transport treatment, and the uranium was concentrated to about 2 wt% as a uranyl carbonate product. Under these conditions, a transmembrane uranium flux of about 2.5 lb/ft2-year was obtained. An economic analysis showed that the cost of recovering uranium from this leach solution via coupled trans-port is about $1.20/lb. At higher concentrations of uranium in the leach solution this cost is reduced. For example, at 1000 ppm the cost of uranium recovery is about $0.30/lb.

Jan 1, 1983

By L. Westerstrom

Supply and Demand After a dismal first half, the industry saw a marked improvement in its markets during the final six months of 1983. Domestic consumption was 17.6% higher in the second half of the year, primarily due to a surge in electric power requirements. The sharp increase in demand for electric power during the third and fourth quarters afforded utilities the opportunity to lower stocks that had accumulated to record levels during 1982. Consumer stocks were reduced from 179 Mt (197 million st) at the end of June to 153 Mt (169 million st) by the end of the year. That is the largest inventory drawdown on record during a six-month period without a major coal strike. Despite the huge depletion in inventories, coal production in the second half of 1983 rose 1.3% above output in the second half of 1982. However, because of the disappointing first half, production in 1983 totaled only 712 Mt (785 million st), 6.4% less than the 760 Mt (838 million st) produced in 1982. Demand The extent to which the economic recovery affected coal markets in 1983 varied: • total domestic coal consumption increased 4.2%; • electric utility coal consumption increased 5.3%; • exports declined by about one-fourth; • coal consumption at coke plants declined 9.5%; and • coal consumption in the other industrial sectors increased 2.9%. Domestic coal consumption totaled 667 Mt (737 million st) it 1983, 27 Mt (30 million st) more than 1982. Electric utility consumption increased from 539 M1 (594 million st) in 1982 to 567 M1 (625 million st) in 1983. Coal consumption at coke plants declined from 37 Mt (41 million st) to 34 M1 (37 million st). Residential and commercial use increased 181 kt (200,000 st) - from 7.4 to 7.6 Mt (8.2 to 8.4 million st). Electric Utilities: Electric power generation increased 3.1% in 1983. Demand for electric power increased in all major consumer categories. Residential and commercial use rose 2.7% and 3.3%, respectively. The most striking increase, however, and indicative of the economy&apos;s strong upturn, was the increase in industrial electric power use. Industrial power requirements, which declined 9.8% in 1982, rose 4.1% in 1983. The electric utility sector continued to expand its use of coal last year while lowering its requirements of oil and natural gas. In 1983, electric generation from coal increased 5.7%, while genera-

Jan 5, 1984

By Chu E. Ho

Current methods of determining jet grout column diameters are highly empirical and site specific, and do not take into account the jet hydrodynamics and soil parameters explicitly. A theoretical model which describes the jet excavation mechanism is introduced in this paper, with the aim of providing an improved prediction tool that can be used in jetting design. The model is based on the assumption that the velocity distribution in the cutting jet is equivalent to that of a free jet with boundaries corresponding to the dimensions of the cavity excavated in the ground. The shape of the cavity formed depends on the erosional properties of the soil and jet expansion is limited by the resistance at the jet-soil interface. The model predicts that the limit of jet penetration is reached when the average dynamic pressure at the jet tip becomes equal to the ultimate soil bearing resistance. The reliability of the model, evaluated using results from four case histories of jet grouting field trials, is within ±15%.

Jan 1, 2006

By D. J. Coolidge, H. L. Sheakley

THIS paper does not deal with all sands used in the glass industry in Missouri; it covers only that used in the plate-glass factory at Crystal City. However, it is probably safe to say that other sands, pro- [ ] duced throughout the state for this purpose, are of identical nature. The glass sand used in Missouri is commonly called the St. Peter deposit, which is ascribed to the Ordovician Rock series in the form of sandstone. This St. Peter deposit, aside from a few small outliers, covers a large area of eastern Missouri. It forms, through a broad curve, the northeast margin of the typical Ozark region between Cape Girardeau on the southeast and Mineola, Montgomery County, on the northwest. The belt is extremely irregular, varying from one to ten miles in width; its length is 150 miles in a straight line. [ ] The outcrop near the entrance to the Crystal City mine appears in the form of a sandstone bluff approximately 30 ft. high, running along Plattin Creek (Fig. , I). Above the sand rock an overburden of Joachim limestone appears, which, thickens to nearly 300 ft. and forms the hill commonly called Buck Knob. Test holes, where drilled at various points and the drillers&apos; log indicate that the St. Peter deposit ranges in thickness from 63 to 71 feet. PROPERTIES OT THE ST. PETER SAND From an analysis of the glass sands of the St. Peter formation in Missouri, the follow-

Jan 1, 1942

By C. V. Corless

1. Introductory Some members may recall that at the Annual Meeting two years ago I read a paper, &apos;The Future of the Mining Industry in Canada." Discussing this large subject it was possible only to outline the facts and inferences leading to ?the conclusion that Canada is a country endowed with enormous mineral wealth, of which the fringes are yet scarcely touched. In the present paper, I wish to examine in somewhat fuller detail the evidence, both direct and inferential, concerning the mineral wealth of the greatest physical and geological feature of Canada-the Precambrian Shield. Many, if not most, of these facts are already familiar to you. But, since they will form the basis of the reasoning employed, they will be recalled for explicit reference. First, let us review very briefly the position and extent of the Shield. The area of the entire Shield is given in textbooks as 2,000,000 square miles, of which perhaps 10 or 12 per cent. is exposed in the south-easterly part of Canada&apos;s Arctic islands. The remainder occupies roughly two-thirds of the North-west Territory; the north-east corner of Alberta; one-third of Saskatchewan ;two-thirds of Manitoba; three-fourths of Ontario; and nearly ninety-five per cent. of Quebec.

Jan 1, 1924

By J. Mitchell Linne

The principal mineral commodity in the Orleans Mountain RARE II area (No. 35019) is gold. Gravel deposits along the Salmon River contain placer gold. Lode gold with associated silver is contained in quartz veins. Many placer mining claims have been located within the study area in the Salmon River district. Four placer patents totalling 230 acres were issued for claims on the Salmon River between Lewis Creek and Forks of Salmon. On this same reach of river, adjoining and overlapping the study area boundary, approximately 3.3 million cu yd (2.5 million cu m) of gold bearing gravel with values ranging from $0.51 to nearly $5 per cu yd (50.66 to $6.50 per cu m) (gold valued at $400 per troy oz), are contained in three placers, the Bloomer, Pot Luck, and Horn (table 1). Within the study area boundary there are approximately 950,000 cu yd (726,000 cu m) of gold bearing gravel in these three placers. These three mines yielded nearly 12,000 oz (373,000 g) of gold and more than 300 oz (25,000 g) of silver between 1872 and 1913.

Jan 1, 1982

By Bradshaw, Y. S. Cho

The size of bubbles plays an important role in flotation. Equations used to calculate the size of bubbles all show the effect of liquid/gas surface tension. However, the surface tension does not change much with frother concentration and experiments conducted using single capillaries (or single-hole spargers) do not reveal any clear effect of the frother concentration on bubble size. The size of bubbles does, however, strongly depend on frother concentration when multi-hole spargers are utilized (or when measured in a flotation cell); at low frother concentrations the bubble size is much larger indicating coalescence as a main mechanism determining the size. Coalescence can be prevented at frother concentrations exceeding the critical coalescence concentration (CCC), which in turn was found to be interrelated with the dynamic foamibility index (DFI).

Jan 1, 2001

By Arthur H. Redfield

The expansion of city street laving which characterized the ten years ended December 31, 1929, according to a survey of 201 representative cities, made by the bureau of Mines, reached it climax in 1927, with decreases reported for 1928 and 1929. The upward trend, followed by a decline, was general in cities of all sizes included in this study, but was most pronounced in cities of 40,000 to 100,600 inhabitant and in the Northeastern, Southeastern, and Southwestern States. In the North-Central States the trend of paving; was downward from 1925 to 1929; in the Pacific, and Rocky Mountain States it was generally upward. Over the nation as a whole, bituminous types of paving continued to lead, furnishing two-thirds of the total street pavement laid in the 201 cities from 1925 to 1929. The actual yardage of bituminous pavement laid in these cities, however, was 3.8 per cent less in 1923-than in 1925, and the ratio of bituminous pavement to the total pavement t dropped from 70.4 per cent in 1925 to 62.1 per cent in 1928, rising to 65.1 per cent in 1929. The area paved with Portland-cement concrete amounted to only one-fourth of the total, pavement laid in these cities from 1925. to 1923., but the yardage of Portland-cement pavement increased by half during the period, and its share in the total pavement grew from 19.3 per cent in 1925 to 30.0 per cent in 1928, declining to 29.5 per cent in 1929. Brick, block, and stone pavements, which constituted the remaining one-twelfth of the total pavement laid in the 201 cities, decreased one-third in yardage, and declined in relative importance from 10.3 per cent in 1925 to 6.6 per cent in 1929.

Jan 1, 1931

By J. Wiese

Recently the operating philosophy at concentrators processing platinum bearing ores has started to move from a recovery dominated system to one in which the production of high grade concentrates at the expense of some recovery would provide greater benefits in the further upgrading of the platinum group minerals (PGM). The low grades usually obtained are associated with the presence of naturally floatable talcaceous gangue minerals in all PGM ores. Polysaccharide depressants such as guar gum and carboxymethyl cellulose (CMC) are used to improve the grades of the concentrates. Recent testwork has shown that the use of high depressant concentrations can prevent any naturally floatable gangue from reporting to the concentrate. The only gangue present in the concentrates would be due to its entrainment in the froth. Under these conditions much higher grades can be achieved. The sulphide minerals themselves, however, become susceptible to depression at high depressant concentrations. This work examines how the recovery of sulphide minerals in two Merensky ores was affected by the type and concentration of the collector in the presence of high depressant concentration (500 g/t) and that the response of the sulphide minerals was also dependent on the type of depressant used (guar or CMC).

Jan 1, 2009

By A. Haines, O. Varaud, I. Baidoo

Abosso Goldfields Limited (AGL) is in the process of developing an expansion of their Damang Open Pit gold mine in Ghana. AGL acquired the Damang mine in January 2002, with SRK participating in the geotechnical investigation and design for the project since 2001. A deep resource drilling program, completed during 2004, intersected an extension of the orebody below the then planned final pit floor. A feasibility study has been completed to determine the economic extraction of this deep ore with an expanded pit shell. The Damang mine is in a stockwork sulphide deposit at the culmination of the Damang anticline. The deposit occurs as hydrothermal mineralisation associated with dominantly east dipping thrusts and sub-horizontal quartz veins. Primary gold mineralisation also occurs in the conglomerates of the Tarkwaian Formation. The geological units consist of steep easterly dipping dolerite, sandstone, siltstone and phyllite beds, with the weathering profile comprising saprolites overlying a relatively thin joint oxidized horizon. It is planned to deepen the current open pit to a final depth of up to 270 m, primarily by the development of a push-back of the eastern and western walls. The edge of the Eastern Tailings Storage Facility (ETSF) is currently located within 80 to 100 m of the crest of the existing pit. The geotechnical design focused on the optimization of the bench face angle and finally recommended a ?Steep Slope Strategy?, involving 24m high near vertical benches. Limiting bench stack heights of 96m at a maximum of 66° were derived from the influence of major structures and the variation in rock mass conditions. The overall slope angles in each pit sector were developed around the requirement for haulage ramps. One of the main design challenges was to optimise the standoff distance between the final pit crest and the ETSF. This process had to consider maximum access to the resource without undue influence on or from the nearby tailings dam. A planned increase to the height of the dam wall was an additional factor in the design. Dewatering of the pit walls was also a major consideration in this tropical environment.

Jan 1, 2006

By R. C. D. Phillis

Conventional stoping in hard rock mining is largely considered an operational environment. This paper suggests that stoping falls within the realm of a project management environment typified by uncertainty, variation, and large numbers of interdependencies. Stoping was then equated to a micro-project with many simultaneous activities that had to be executed accurately using finite resources within limited shift durations in order to reach specific goals. Critical chain project management (CCPM) principles were applied to the stoping activities, and the results showed that the number of blasts per panel can be significantly increased by successfully moving the distribution of work as close as possible to the start of shift. Critical chain principles also assisted in facilitating re-focusing and teamwork among stoping crews as well as between day- and night-shift crews. The main recorded success was in managing inherent protective capacities/local contingencies/fat/buffers that are found in all projects. The impact on mine health and safety (MHS) was significant as individual operators and crews became convinced that they could perform all stoping tasks (activities) without compromising accuracy or speed.

Jan 1, 2011

By M. B. Shongwe

Pt-based alloys are being developed for high-temperature applications with the aim of replacing some of the currently used Ni-based superalloys (NBSAs) in the highest temperature applications. The Pt-based alloys have a similar structure to the NBSAs, and since Pt is more chemically inert than nickel and has a higher melting point, they can potentially be used at higher temperatures, up to 1300°C, and in more aggressive environments. Several experimental Pt-based alloys were studied at Mintek, and an optimum composition was found to be Pt84:Ahi:Ru2:Cr3 (at.%). On the basis of hardness and microstructure, a later study identified a new optimum: Ptr8:A111:Ru5:Cr6 (at.%). There are at least two Pt3A1 allotropes, and the high-temperature cubic structure has better properties than the lower temperature tetragonal form, and so needs to be stabilized. This work describes the latest results obtained in transmission electron microscopy (TEM) studies of the quaternary Pt-based superalloys. These results are both interesting and important, because the samples have a higher precipitate density compared to those from earlier work. The precipitate morphology is mainly cubic, with minor areas having irregular-shaped precipitates. The high volume fraction of the precipitates is a major breakthrough, since the objective of this work is to improve the alloys. A prior disadvantage was that the proportion of the precipitates was too low in samples before this work, especially compared with the work from Germany on Pt-Al-Cr-Ni¬-based alloys as well as the NBSAs. TEM -Pt3A1 diffraction patterns were studied, and for each diffraction pattern, many possible lattice point combinations were tried, with the angle between the lattice spots as well as interplanar spacings being calculated for each phase (cubic or tetragonal) to match the measured results. An overall analysis of the diffraction results indicates that the cubic phase fitted the experimental lattice points with much lower errors compared to the tetragonal phase. Thus, with the close match achieved with the cubic structure, the structure of -Pt3A1 precipitates is likely to be cubic. X-ray diffraction has been carried out on selected samples, and the results confirmed the presence of cubic -Pt3A1 and (Pt). Different X¬ray diffractometers were used to further verify the results, and the results were also compared with those from TEM.

Jan 1, 2012

By P. A. Rey

Water recycle is an important part of the coal preparation process. This study was directed toward: (1) a survey of current practice and an evaluation of both the solid and liquid components of blackwater, (2) an experimental study of blackwater flocculation, and (3) a fundamental analysis of the flocculation process. The solids contained in the blackwater discharge to the fine refuse thickener of a coal preparation plant were found to contain, on average, 56% coal and 44% mineral matter. The mineral matter was largely illitic clay, while the water phase contained relatively large amounts of S04 and Ca++. Detailed studies were made of both natural and synthetic flocculants and the influence of polymer type and pH on the settling rate, turbidity of the supernatent liquid and sludge volume of the settled solids. More tundamental studies were made that clearly indicate the need for controlled mixing of polymer into the suspension to be flocculated, and the need to evaluate, more closely, the structure of the flocs formed during the process. Research recommendations are given.

Jan 1, 1983