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By Pengqi Zhang, Mingcheng Bing, Lixiong Shao, Shuxing Qiu, Qingyun Zhang, Shengfu Zhang

Coal desulfurization has been regarded as an effective pretreatment for clean fuel and less environmental pollution. The microwave irradiation was used to desulfurize the Nantong coal leached with H2O2 and NaOH. The results showed the desulfurization rate of the coal is very low by directly microwave irradiation, while the coal samples leached with H2O2 and NaOH by microwave irradiation could effectively improve the desulfurization rate. The optimum desulfurization conditions were obtained as 10-min irradiation time, 800 W irradiation power, particle size below 74 μm, 1:1 concentration ratio of H2O2:NaOH, in which the desulfurization rate reached 51.14% of the total sulfur content. Attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectra of coals structure before and after treatment have shown the bands in both coals changed slightly except the relative intensity of some absorption ones. It can be found that most of FeS2 and –S–S– functional groups transferred after treatment, while –SH and –S=O– had almost no changing by ATR-FTIR spectra analysis. The structures of coal matrix would not be broken by microwave irradiation in reasonable the reaction conditions.

Mar 1, 2017

By Howard E. McKinney

A high-pressure wellhead lubricator has been developed to facilitate telemetering electrical measurements from subsurface reservoirs to the surface with the well under normal flowing conditions. The field unit in use at the present time employs a 5/16-in diameter, single-conductor armored cable and is to be used in wells with surface pressures up to 5,000 psi. It has a pressure sealing element that maintains a continuous and absolute seal around the cable as it enters or leaves the tubing at speeds up to 175 ft per minute. A cable injecting device is used which obviates sinker bars or weight sections on the instrument. INTRODUCTION The development of instruments for securing physical measurements in pressure wells has been confined in the past to those instrument which would operate on a wire line and record the necessary measurements in the downhole instrument itself, or those which would operate on an electric cable in a well with the surface pressure killed by the use of weighted fluids or by the use of tubing plugs. In one case the accuracy of the measurements is questionable, and in the other the range of application is very limited. Considerable work has been done by other interests to provide effective means to accomplish the necessary telemetering. The U. S. Bureau of Mines developed a wellhead lubricator prior to 1947 which permitted a 5/16-in diameter single-conductor cable to be lowered into a well with a surface pressure of approximately 500 psi. This unit was used successfully in a number of tests in Oklahoma. A company which tests wells has recently offered on a service basis a wellhead lubricator with a 3/16-in diameter cable that reportedly operates up to 2,500 psi surface pressures. Each of the above operates on a staging principle to effect a seal. In both of these units some leakage of well fluid occurs when the cable is moved. SPECIFICATIONS FOR DESIGN In order to provide the maximum flexibility in its use, the following parameters were established for the design of our high-pressure wellhead lubricator: L An absolute well fluid seal up to 5,000 psi surface pressures. 2. Means for raising and lowering the instrument at speeds of at least 100 ft per minute. 3. Provision for the instrument to enter and leave the well without disturbing the well flow or the reservoir conditions. 4. A cable large enough to provide suitable electrical characteristics and suitable mechanical properties. 5. A method of operation that will not damage the well in any way. The present high-pressure wellhead lubricator field unit fulfills the above requirements. DESCRIPTION OF THE UNIT AND ITS OPERATION The cable selected for this use is the standard Amergraph 1H2 as manufactured by the American Steel and Wire Co. This particular cable is normally used by the Halliburton Oil Well Cementing Co. in their conventional well logging operations. Although the cable presents a noncircular cross-section (Fig. l), its diameter is very consistent; lor example, maximum diameter is 0.325 in., minimum diameter 0.314 in. This [actor permits the use of the sealing element, as later described. Early in the development of the high-pressure wellhead lubricator it was apparent that we could not effect a direct gas seal around a moving 1H2 cable. This becomes evident when an examination of the cable cross-section is made. The voids between the strands of the outer armor provide natural channels lor the flow and escape in large quantities of a low-viscosity fluid such as gas. However, it is relatively simple to

Jan 1, 1952

By A. W. Laughlin

Laser-Induced Breakdown Spectroscopy or LIBS can be used to provide exploration companies with precise and accurate chemical analyses in the field, in real-time, resulting in major time and cost savings. Using a Field-Portable Analyzer (FPA), anomalies can be followed up immediately while crews are still in the field. Lower limits of detection (LLDs) are element dependent, but many are sufficiently low to be useful in exploration. LLDs in ppm for selected elements of interest are: Be-2, Cu-3, Zn-20, As-200, Sb-500, Pb-30, Ag4, Mo-100, B-33, Ti-500, V-350, and Cr-1. LIBS analyses require little or no sample preparation.

Jan 1, 1999

By C. M. McCulloch

More and more mining underground is being conducted using the longwall method. Likewise, many new surface mines use area or mountaintop removal methods. These methods can have a significant impact on surface and groundwater resources. The overall study of the effects on surface and groundwater from mining is referred to as the probable hydrologic consequences (PHC) determination of mining and reclamation. Collection and interpretation of information concerning groundwater and surface water quality and quantity, as well as detailed geologic analysis, is required to adequately define the impacts of mining. This paper discusses the present day requirements and methodology of preparing a PHC for a large mining operation in the eastern coalfields.

Jan 1, 1995

Current scrubber capacities vary from 1.89 to 4.72 m3/s (4,000 to 10,000 cfm), and there is interest in using scrubbers with capacities up to 6.61 m3/s (14,000 cfm). This paper describes research to compare the effectiveness of blowing and exhausting face ventilation systems using high-capacity scrubbers with flows up to 6.61 m3/s. Tests were conducted in a surface ventilation gallery with exhaust and blowing systems operating under similar conditions. The mining machine was equipped with a machine-mounted scrubber. Methane gas was released at constant flow at the mining face and measured at several face locations. Effectiveness of exhausting and blowing systems was compared by determining average face methane concentrations. For each operating condition tested, blowing ventilation was more effective than exhausting for controlling face methane levels. Raising scrubber flow to 6.61 m3/s reduced methane levels for both blowing and exhausting systems.

Jan 1, 1996

By David R. Black

Foundation problems due to collapsible and expansive soils are well known throughout the arid western United States. Millions of dollars are spent annually to counteract the effects of such soils for both new foundations and existing foundations suffering from settlement or heave. Over the last 20 years helical screw piles have come into wide-spread use as a permanent deep foundation element for these problem soils, especially in the arid western United States where, in some areas, they are a standard of practice. Independent research resulting in recognition by every national building code in the United States has legitimized helical screw pile technology. Once thought of in terms of light structural underpinning, helical screw piles of today are designed to take heavy structural loads, vertical and lateral, tension or compression, including seismic loads. With proper pile grouping, design capacities for column loads over 4,500 kN (1,000 kips) are attainable. This paper discusses design considerations specifically dealing with collapsible and expansive soils: soil investigation parameters, predicted settlement and long-term creep, heave in expansive soils, downdrag in collapsible soils, shaft slenderness buckling, maintaining shaft alignment during installation, refusal condition, water migration along the shaft, lateral loading, cyclical loading for seismic loads and machine foundations, corrosion, helix durability during installation, the installation torque vs. capacity equation, and design methodology. The paper concludes with several case histories where helical screw piles were used for new structural foundations and to underpin existing failed foundations in St. George, Utah, Cedar City, Utah, and Denver, Colorado, USA, sites of some of the most expansive clay and collapsible soil in North America. Soil descriptions and performance histories are presented.

Jan 1, 2002

By R. Bruce Thorndycraft

Pinson Mining Company was formed to develop a gold orebody located in northern Nevada near Winnemucca. A feasibility study was undertaken in 1979 by a consortium of three Toronto-based mining companies and a Reno-based exploration company. The study indicated a viable project with gold priced above $225 per ounce. A project manager, and mine and mill superintendents, were hired in late 1979 to expedite the development of a 1000 ton per day mine-mill complex. Plant design engineering was contracted with Industrial Design Corporation in Salt Lake City. Three experienced plant metallurgists representing Pinson were stationed in Salt Lake to guide the work of Industrial Design. Among the many design criteria spelled out by Pinson, foremost were bringing the mill on line as quickly as possible at minimum capital cost. Fourteen months after the beginning of design engineering, the completed Pinson mill became operational. Total capital cost, including mine development, was $18 million. The Pinson project has proved to be far more than viable; the entire capital cost will be recovered within 18 months of the mill start-up.

Jan 1, 1982

By W. A. Padgham, H. Helmstaedt

Field evidence for current hypothe e about age and kinematic ignificance of gold-bearing hear zones in the Archean Yellowkni fe greenstone belt is reviewed , and it is concluded that major disagreements between previous workers are a direct result of differences in stratigraphic and tructural in terpretations of the Yellowknife Supergroup. Although goldbearing hear zone appear to be confined to the mafic volcanic pile of the Kam Group. it can be shown that shearing affected all supracru tal rocks, including the Jackson Lake Formation. now con idered to represent the youngest unit of the Yellowknife Supergroup. tructural ob ervations are incompatible with the hypothe is that the hear zones represent loci of ynvolcanic gravity sliding but are consistent with earlier conclu ions that shear zone development commenced with rotation of the volcanic pile and continued as re ult of lateral shortening broadly overlapping with the emplacement of granitoid batholiths. Shear Zones are common throughout the entire green tone belt. yet productive zone are confined to the Yellowknife Bay Formation of the Kam Group and localized where flow abut with a high angle again t the contact of the We tern Plutonic complex. However. no obvious tructural and lithological features have been recognized that are more favorable for gold deposition and distinguish the shear zones and flows of the area around the mines from those of other parts of the greenstone belt. The model that gold wa transported by metamorphic solutions and that hear zones were the firs t-order control for gold deposition provides no explanation for the trong localization of the depo it . As porphyries with elevated gold contents are present in and near ome of the mines. the possibility that gold was deposited from hydrothermal system around fel ic intrusion representing early phases of the Western Plutonic complex should be given erious consideration.

Jan 1, 1986

By Lindsly. Ben E.

"The recovery or partial recovery of the oil remaining in oil sands after the usual methods of production have become unprofitable is perhaps the greatest problem in the petroleum industry today. The amount of this oil remaining in the sand is variously estimated by those familiar with the subject to be 25 to 90 per cent of the original content.2Lewis3 states, ""The estimate of 80 to 90 per cent of the oil left underground does not seem incredible.""It is estimated by the writer that approximately 91 per cent of the oil originally held in the Elliott pool, was still in the formation on January 1, 1924, and that it would take at least 12 years, at the 1923 rate of production, to further reduce this quantity by one per cent of the original content.The progress made in the oil industry during the past few years relative to the prevention of evaporation losses; to improvement in cracking processes, whereby the gasoline yield from many crudes has been doubled and trebled; to the increased recovery of gasoline from natural gas; and many other developments, remarkable as they are, can be applied only to that comparatively small portion of petroleum products which are raised to the surface. A device or process which would cut development costs to one-half would probably result in a much smaller profit to the oil industry, than the profit derived from an additional 10 per cent recovery of the total amount of oil in a pool. Various methods have been used and many others proposed, for the increase of oil recovery from normally depleted sands.In France, oil sands are being mined by means of shafts and galleries. In other places, notably the Bradford, Pennsylvania field, the yield has been increased by means of water flooding, wherein water is introduced into the sand to displace oil, and drive it to producing wells."

Oct 1, 1926

By M. Saghaeian, R. Hejazi, M. Farahani, M. Dehghani, A. Tohry

"Wet tailing dams of iron ore processing plants typically contain a significant amount of valuable minerals. In more recent years, due to the increase in iron’s prices and technological innovations, as well as the low energy consumption which required for processing of materials from tailings, dams can consider as potential valuable deposits. However, the production of iron concentrate from tailings is usually complicated where the high moisture content of the material, the high clay content and the presence of chemicals of processing such as flocculants, acids and flotation reagents, all make materials highly sticky which can be easily swollen. In the present paper, the optimization of operational parameters to recover ultrafine hematite iron ore from the wet tailings dams of the Chador-malu iron ore mine was investigated. The optimization of operational parameters, showed that with modification of the washing unit components for slurry making, the challenge of constraints from feeding the plant could be overcome. To decrease the magnetite content in the tail stream of the medium intensity magnetic separation (MIMS) and subsequently increase the efficiency, the orifice of the cleaner tail flow exit pipe was changed from 7 inches to 3 inch and yoke angle changed from 14 to 8 degrees. These changes increased mass yield by 3% and decreased the magnetite content in the final tailings to 1.2%. By recirculating the cleaner SLons of final tailings within the circuit, the solid percentage of the feed to rougher SLons decreased to around 15%, and as a result the matrices were not overloaded that easily, and mass yield increased to about 13% from 7%. All the above mentioned optimizations were achieved without significantly affecting the concentrate Fe grade."

Jan 1, 2018

By Reginald N. Boryor, Steven D. Woods

1.0 Introduction ?Low grade, high tonnage, open pit gold mine. ?Gold bearing Tarkwaian conglomerates. ?Reverse Circulation percussion drilling (25m X 25m grid). ?Composite 1m intervals, logged and split in the field to provide±2Kg samples. ?Samples used to build grade control block models using SURPAC. ?Approximately 100,000-130,000 meters drilled per year. ?RC samples are assayed using Rapid Cyanide Leach (RCL). ?Check assays are done using Fire Assay

Jan 1, 2005

By A. F. Peterson

There is no single mining problem at Benson that does not exist at some other mine. There are four, however, that require special attention primarily because they occur together and have an influence on each other. These are the nature of the mineral occurrence, the shape of the ore body, the operating schedule, and the climate. It is the purpose of this paper to describe mining practices in relation to these four factors. Iron ore was first noticed in the Star Lake area early in the nineteenth century. Prior to Jones and Laughlin leasing the facilities built by the Defence Plant Corporation, several companies tried to mine the ore body but gave it up as uneconomical. While there is a little high grade (40%) magnetite, most of the ore contains 20 to 25% iron and not enough was known prior to World War II to design a profitable operation. By 1943, and certainly in the years that followed, technological developments in ore dressing and mining not only put the magnetite into the category of a commercial ore, but made possible the concentration of the non-magnetic iron mineral, martite. This last development nearly doubled the ore reserve. Jones and Laughlin bought the DPC holdings in 1946 and has since expanded the plant to its present capacity of 4,400 gross tons of concentrates daily or 1,600,000 gross tons per year. Magnetite makes up 62% of this production at the present time, but it will be necessary before long to bring martite production up to about 45% of the total because of the ratio of the two ores in the reserves. To keep the plant supplied, 14,000 to 15,000 tons must be mined and crushed daily, with a ratio of concentration that varies from 2.8 to 3.4. The ore body is 12,000 feet long and varies in width from 600 to 1,500 feet. The waste rock is, for the most part, a granite gneiss, and the overburden, of which little is left, is a glacial drift sand. For the entire reserve, there is a half ton of rock for every ton of concentrate, but the stripping ratio is more than one to one at present because of the existence of more rock in the upper mining levels in relation to the ore. The dirt stripping or development work that cannot be handled by company facilities is contracted to an outside firm. The need for this diminishes every year and will soon disappear. The deposit looks like a "J" in plan, with the long leg running approximately north and south and the short leg to the west. The primary crushing plant, consisting of a 54" gyratory followed by two 18" gyratories and a 1,500 foot conveyor belt to the fine crushers, is located on the third level where the long and short leg of the mine meet. The widest part of the pit lies just the north of the crusher. The mine is operated on a lease that expires in 199l0 There are two fee owners, the Benson Iron Company, which owns slightly overhlf of the reserves, and the Newton Falls Paper Company, which owns the balance. There is no appreciable difference in the mining on the two fees, so the ore is removed in strict proportion to calculated reserves during each year. Basic mining equipment consists of eight 45 yard electric shovels, a fleet of twenty-five 22 ton end dump trucks, eleven churn drills for nine inch blast holes, and two small percussion drills for four to five inch holes, There are the normal auxiliary items, such as dozers, graders, wagon drills, and two drop-ball cranes. Power is purchased and, where practical, is used at 4100 volts. Pit drainage pumps can handle a maximum of 11,500 GPM from the several sumps, but water is a problem only during the spring or when a sudden thaw follows a heavy snowfall.

Jan 1, 1958

By Pitter Chumpitaz, Pedro Gonzáles, César Espejo

En nuestra Planta de procesos de La Arena, uno de los principales insumos químicos en nuestro proceso es el cianuro de sodio. La lixiviación del oro con una solución de cianuro sigue siendo el proceso hidrometalúrgico más ampliamente utilizado para la extracción de oro en los minerales. El cianuro de sodio por ser parte esencial del proceso también es el que tiene un alto impacto en los costos operativos del área. En base a resultados de pruebas metalúrgicas se concluyó que, a partir de la segunda mitad del ciclo de lixiviación del mineral, el requerimiento de cianuro para continuar con la lixiviación del oro es menor. Es por ello que se analizó la viabilidad de implementar un sistema de bombeo para realizar un riego diferenciado en el Pad y así optimizar el consumo de este reactivo.

Sep 30, 2022

By Pedro Antunes Amaral

Currently there is a constant and essential concern of preserving nature. Over the years the concern with the environment is increasing, new environmental laws are emerging and being applied more rigorously and consequently emerge economic needs and mineral processing practices and other materials. In this sense briquetting becomes an alternative to fine particles agglomeration by means of pressure and or temperature, with the aid or not of a binder, which allows to get a product not only compressed, which presents shape, size, and adequate mechanical properties. The reduction in volume of the material in some cases (beyond the technological benefits) also allows fine materials can be transported and stored more economically, safely and effectively. The production of coke is greater as the content of better coking coal is, thus he low capacity coking coal is not much used in coke ovens. This research aims to demonstrate that briquetting of mineral coals with low coking coal capacity is possible, additionally allows increased coke production, obtaining then a better yield of coke. Basically they take advantage of low price of no coking coals without changing the quality of the coke produced. Anyway, briquetting became a smart alternative to aggregate values, economy and care for the environment.

Oct 30, 2017

By F. R. Archibald

MR. A. F. B. Norwood: Having been associated in the past few years with nine different plants roasting aurif erous concentrates in Australia, two of which were new installations for which design and construction were undertaken by the writer, I read Mr. Archibald's paper with very great interest, and I deem it a great privilege, as a member of a sister Institution, to be invited to contribute to the discussion on the paper. I wish to congratulate the author on a very informative and interesting paper, and, although situated many thousands of miles away, I feel I have gathered from it a very close idea of the operating conditions and of the work that has been carried on at the Beattie gold mine. Working along somewhat different lines, it is interesting to note that the conclusions drawn by the author run closely parallel to those accepted in Western Australia, viz., that the object of roasting is to obtain a porous calcine, and that this can best be achieved by roasting first at a temperature below 900 deg. F. to 1,000 deg. F., and then raising the temperature at the finish of the roast. Turning first to the laboratory work, the materials I have studied in Western Australia cover a range from those with little or no arsenic to concentrates carrying as high ?as 20 per cent, i.e., even higher than in the analysis quoted for the eoncentrates from Nepheline Products, Limited. In the ease of arsenic-free pyrite concentrates, the roast is ideally carried out at a temperature ranging from 900 deg. F. to 1,000 ferric oxide is one cause of the refractory gold remaining In deg. F. No improvement in extraction is obtained when the calcines are cyanided by raising the final temperature above this point; nevertheless, in technical practice it is desirable to finish the roast at 1,200 deg. F. in order to decompose basic ferric sulphate and thereby reduce the consumption of chemicals in the subsequent cyanidation step. However, if at any stage of the roast the temperature is raised above 1,200 deg. F., the extraction by cyanidation falls, and continues to do so the higher the maximum temperature that is reached. Line A in the accompanying graph typifies this effect.

Jan 1, 1949

By W. G. Campbell

"The region discussed comprises approximately eight million acres spreading across the Arctic Circle in Yukon and North West Territories.Encouraged by four years of surface geological and geophysical work, which strongly suggested that suit-able conditions existed for the entrapment of oil and gas, a decision was reached to drill. In due course two holes were drilled; Eagle Plains No. 1 drilled to 9589 in 1957-8 and Western Minerals Chance No. 1 spudded in 1959 is being deepened this year.Thick sections of sedimentary rocks occur on both sides of the Richardson Mountains, however, most of our activities have been concentrated to date on the west side in the Eagle Plains basin. Here are found stratigraphic units ranging from Precambrian to Tertiary age. The drilling of the two exploratory wells proved the presence of these strata at depth and have confirmed the presence of promising structures. A geological cross-section across Eagle Plains presents an interpretation of these conditions.Physical and engineering aspects of exploration in the northern Yukon and North West Territories are de-pendent largely upon seasons and transportation. Reconnaissance gravity and surface geologic mapping by air presents no serious problems. However, seismic operations on the ground are greatly affected by the season, presence of permafrost and mobility of equipment.The actual drilling of the hole may well be the simple part of a wildcat undertaking once equipment and supplies are on location. Over-all planning, assembling supplies, transporting equipment and personnel seems to be the real job. Serious consideration must be given to per-ma-frost effect in the drilling pro-gram and on surface installations as well.Programming for -the various exploration activities should be under-taken well in advance of the actual doing. Considerable extra costs may be the results of crash programs. Costs are high, and the rewards uncertain. Economic evaluation is based •on the long term outlook."

Jan 1, 1960

By B. C. Morrison

Because of U.S. Forest Service regulations and the consequent cost of leaving several diamond drill holes open at the same time, it was necessary to develop an electrical method that could be used in one hole at a time to extend known mineralization. This was achieved by balancing the surface current electrodes so that the two potential electrodes in the hole being surveyed were in the same equipotential surface. This condition eliminated stratigraphic response but enhanced any asymmetry due to ore between the hole and either current electrode. This method was successfully used in mineralized holes at West Fork, Reynolds County, Mo., to show the direction in which to extend the drilling into areas of better mineralization.

Jan 1, 1972

By Marshall K. I

THE problem of satisfactorily eliminating the fumes and dust which are unavoidably produced in various metallurgical and manufacturing industries is one which has received considerable attention in the past, and has been the subject of much investigation and research. The solution of this problem was urgently desired for two reasons, the principal one being the fact that a considerable percentage of the total process losses in many industries was represented by the commercial values of the fumes and dust that escaped from the stack.The other reason is that, in some instances, the emission of the matter is regarded as objectionable. Various methods have been designed with a view to solving the problem thus presented, and the latest development that has beendesigned is the process of electrostatic precipitation. Continued investigational and developmental work with this process has already demonstrated its applicability to many industries, and new uses to which the process can be put are being opened up. Its use is already widespread, and the economic success that has attended its application in most instances would indicate that its use will become more general in the future.It has proved its ability to treat gases over wide ranges of temperature, and has successfully handled various types of fumes whose chemical characteristics differ very considerably. In many processes it has now come to be regarded as standard equipment.HISTORY OF ELECTRICAL PRECIPITATIONThe first recorded observations on the influence of an electrified insulated wire on gases containing solid particles in suspension was made as early as 1824 by Hohlfeld, in Leipzig. He found that, if he electrified a wire hung in a bottle filled with smoke, the smoke cleared rapidly, and a deposit formed on the sides and bottom of the bottle.

Jan 1, 1923

By Denni Nikols

"Planning for coal beneficiation in the electric utility industry is relatively complex, involving the coordination of experts and specialists in a broad range of fields, as well as compliance with a wide variety of government regulations.This paper examines the role of the planner, reviews possible benefits of coal beneficiation, identifies potential problems and illustrates a typical planning schedule.The steps involved in the planning process are:Step I-Bench- and pilot- washability studyStep 2- Wash plant designStep 3- Power plant and boiler designStep 4-Mine designStep 5-Major environmental and technical problems to address.IntroductionElectrical utilities and coal have a long and intimate relationship . Cleaned coal is becoming an increasingly popular fuel with the utilities for a variety of reasons. Generally, the greatest impetus to burn a cleaned or prepared coal fuel comes from the need to control airborne pollutants.Long-range planning is a standard practice for electric utilities, forecasts of demand must be made well into the future. Since the lead time required to provide new facilities is often as long as 10 years and the cost very high , planning becomes an important task.For a utility that owns and directs the operation of its coal mines, the mine planning or fuel acquisition planning takes on the magnitude of other corporate planning functions. It is from this perspective that a utility would view coal preparation. Except for the interaction of a coal-fi red plant on the actual mine design the planning considerations o f a beneficiating facility for a captive mine or a contract raw coal supply are about the same. Because TransAlta Utilities is currently supplied from captive mines, this discussion will tend to focus in that direction.It is the role of a planner to plan. This is easy to say but it is not always easy to do. Often we are working within a context that resembles the geological time scale. Frequently the objectives are not clearly defined when we begin and ultimately our plans are tested in the waters of government regulations and cost benefit analyses .Planning for beneficiation of Plains coal, or any coal, provides just such a test. The planner's role in this endeavour requires a wide vision. While parts of the process may be amenable to classical methods of project scheduling, the broad range of subjects and interaction of seemingly unrelated tasks is sure to obscure some of the considerations that must be made. Therefore, the planner's chief role is coordinating the work of many experts and specialists toward the final objective.Among the specialists are combustion , geo technical, mining, civil , and mineral processing engineers , geologists, hydrogeologists, soil, and reclamation experts to list a few.When one considers coal beneficiation, the planning part o f that consideration is probably more complex than any other single engineering function. Due to the company's location in the Alberta Plains and the proximity o f the mine to the thermal generating station, this paper will tend to emphasize that situation.Beneficiation may offer some advantages over run-of-mine coal to the power plant opeator. Some of these advantages are: removal of a contaminant, power plant efficiency gains , lower plant capital costs (for new plants), possible lower mining costs."

Jan 1, 1984

By D. S. Flett, D. W. West

The solvent extraction of chromium 111 has been studied for the system Cr 111, H,SO., H,O/RNH/RNH., xylene, where the primary amine used was Primene JMT. Rate studies have shown that extremely long equilibrium times are required, ranging from 1 hr at 80°C to 20 days at room temperature. Heating the solution prior to extraction increases the rate of extraction. The variation in the amount of Cr 111 extracted is an inverse function of the acidity of the aqueous phase. Thus, the slow rates of extraction appear to be connected with the hydrolysis of the Cr I11 species. Extraction isotherms for the extraction of Cr 111 have been obtained for two sets of experimental conditions, namely at 60°C and for a heat-treated solution cooled to room temperature. The separation of Fe 111 from Cr 111 and Cr 111 from Cu 11 in sulfate solution by extraction with Primene JMT has been studied and shown to be feasible. A survey of the literature relating to the solvent extraction of chromium showed that, although many systems exist for extraction of Cr VI, only a very few reagents have been found to extract Cr 111. The extraction of Cr III by di-(2-ethyl hexyl) phosphoric acid has been reported by Kimura.' A straight-line dependence of slope —2 was observed between log D,, and the log mineral acid concentration at constant extractant concentration. Since the slope of this plot reflects the charge on the ion extracted, it must be concluded that a hydrolyzed species of Cr III is being extracted. Carboxylic acids generally do not form extractable complexes with Cr III but di-isopropyl salicylic acie does extract Cr 111. Simple acid backwashing of the organic phase, however, failed to remove the chromium. Similar difficulty in backwashing was found by Hellwege and Schweitzer8 in the extraction of Cr I11 with acetyl-acetone in chloroform. The extraction of Cr 111 from chloride solutions by alkyl amines has been reported4-' but the maximum amount of extraction achieved in these studies did not exceed 10%: From sulfate solutions, however, Ishimori" has shown that appreciable amounts of Cr I11 were extracted by amines. The amines used were tri-iso-octyl amine, Amberlite LA-1 (a secondary amine, Rohm & Haas) and Primene JMT (primary amine, Rohm & Haas). The efficiency of extraction with regard to amine type was primary>secondary> tertiary. Appreciable extraction of Cr I11 was recorded for Primene JMT as the aqueous phase acidity tended to zero. The major difficulty with Cr I11 in solvent extraction systems stems from the nonlabile nature of the ion in complex formation. This accounts for the slow rate of extraction generally experienced and the difficulty encountered in backwashing the Cr I11 from the organic phase in the case of liquid cation exchangers. Consequently, the possibility of extraction of Cr I11 as a complex anion is attractive since the backwashing problems should be minimized in this way. From published data, it appeared that the extraction of chromium from sulfate solutions of low acidity by primary amines afforded the best chance of success for a useful solvent extraction system for Cr iii This paper presents the results of a study of the extraction of Cr I11 from sulfate solution by Primene JMT and examines the application of such an extraction procedure for the recovery of chromium from liquors containing iron and copper. Experimental Chromium solutions were prepared from chrome alum in sulfuric acid and sodium sulfate so as to maintain a constant concentration of sulfate ion of 1.5 molar. Solutions of Primene JMT were prepared in xylene and the amine equilibrated with sulfuric acid/sodium sul-fate solutions, of the same acidity as the chromium solution, until there was no change in acidity between the initial and final aqueous phases. The solutions of Primene JMT conditioned in this way were then used for the equilibration experiments. Equilibrations at 25°C were carried out in stoppered conical flasks shaken in a thermostat; equilibrations at all other temperatures were carried out in stirred flasks in a thermostat. After equilibration, the phases were separated and analyzed for chromium. In the tests on the rate of extraction, small samples of equal volume of both phases were withdrawn from time to time and the chromium distribution determined. The chromium analyses were carried out either coloi-imetrically using diphenyl carbazide, or volu-metrically using addition of excess standard ferrous ammonium sulfate and back titration of the excess iron with potassium dichromate. The oxidation of Cr 111 to Cr VI in the case of the raffinate solution was effected by boiling with potassium persulfate in the presence of silver nitrate and, for the backwash solution, by boiling with sodium hydroxide and hydrogen peroxide. Results Preliminary experiments indicated that extraction results were effected by the age of the chromium solution, higher distribution coefficients being obtained with solutions which had been allowed to stand for some time. Consequently a stock solution of chrome alum, 10 m moles per 1 Cr I11 in 1.4 M Na,SO,/O.l M &SO,,

Jan 1, 1971