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By John R. Green

Rotary kilns, varying in construction, are used in a variety of processes. Products differ and operating conditions vary accorcling to economic requirements. All of these variables influence the degree of instrumentation and type of control necessary or profitable to install. Products fired in rotary kilns are the results of combined temperature and time treatment and the interrelation of these two factors should be kept constantly in mind in the perusal of this paper. Measurements of Kiln Temperature The securing of proper temperatures within the rotary kiln, either of the charge or of the kiln lining in the high fire zone, are basic objectives of kiln operation; therefore the measurement of these high-temperature conditions merits first consideration. For these measurements, radiation pyrometers, properly designed and protected, have proved adequate, particularly where records ox automatic control are desired, while Optica1 pyometers may serve as portable indicators. Light-sensitive devices or photoelectric cells in this service are capable of producing records as well as certain forms of automatic control. High-temperature measuring devices for rotary-kiln work should have the measuring unit protected from dust, as a continued accumulation of deposit would lower the readings. Fig. 1 shows a typical application of radiation equipment to a rotary kiln, mounted far enough away from the sighting hole through the kiln hood to be protected From puffs or stingouts and with a sighting tube having a series of settling chambers, to prevent dust from reaching the lens. Although dust conditions inside the kiln itself usually fluctuate considerably and have their effect upon the readings at that moment, such effects are not cumulative and show as a continuous fluctuation in the temperature indicated, provided the radiation unit and recorder are responsive to such slight and rapid temperature fluctuations. The ambient temperature to which a measuring unit is subjected fluctuates from possibly 0" to over zoo°F., therefore these changes should have no effect upon the final reading or upon the life of the measuring unit. A very narrow sighting angle is desirable, so that measurement of temperature may be made as far as possible into the high fire zone without effect of the flame temperature. There should some sighting means on the measuring unit, so that the proper field may be viewed. Measurement of wall temperature taken at a point where the charge has just left the wall is less affected by dusting conditions than when taken elsewhere. Factors influencing Temperature Table I gives an outline of the factors that produce kiln temperatures and comments on the possibility of measurement and control. Of greater number and of varied influence are the factors that control when, where and how the heat is delivered to the kiln, the type of flame and the rate of

Jan 1, 1942

By H.A. Bedworth

AlloTs of copper and silicon have been known for one hundred years or more but the commercial development of this type of alloy has taken place during the past few years. In 1905, Sperry l proposed the use of copper-silicon alloys for springs and other purposes for which copper-tin bronzes were used. Some attention was given to this proposal at the time but no one succeeded in producing a practical alloy containing more than a fraction of a per cent. of silicon. The equilibrium relations of the copper-silicon system were studied first by Rudolfi2 and later by Sanfourche 3 and Corson. 4 The constitution of the system has also been recently investigated by Matuyama, 5 and in the laboratories of the American Brass Co. by Smith. 6 Some of the physical properties of the copper-silicon alloys have been investigated by Norbury7 and by Geiss and Van Liempt.8 Summarizing the results of various investigators of the constitution of copper-silicon alloys, the solubility reaches its maximium value, 6.7 per cent. silicon, between 721" and '782" C. At 852" (1. the solubility is 5.25 per cent., while at 400" C. it is only 4.1 per cent. silicon. The copper-silicon alloy begins to get so hard at about 3 per cent, silicon that it is difficult to manage. It was found by Jacobs that the addition of manganese to this alloy considerably improved the working

Jan 1, 1929

By H. A. Bedworth

AlloTs of copper and silicon have been known for one hundred years or more but the commercial development of this type of alloy has taken place during the past few years. In 1905, Sperry l proposed the use of copper-silicon alloys for springs and other purposes for which copper-tin bronzes were used. Some attention was given to this proposal at the time but no one succeeded in producing a practical alloy containing more than a fraction of a per cent. of silicon. The equilibrium relations of the copper-silicon system were studied first by Rudolfi2 and later by Sanfourche 3 and Corson. 4 The constitution of the system has also been recently investigated by Matuyama, 5 and in the laboratories of the American Brass Co. by Smith. 6 Some of the physical properties of the copper-silicon alloys have been investigated by Norbury7 and by Geiss and Van Liempt.8 Summarizing the results of various investigators of the constitution of copper-silicon alloys, the solubility reaches its maximium value, 6.7 per cent. silicon, between 721" and '782" C. At 852" (1. the solubility is 5.25 per cent., while at 400" C. it is only 4.1 per cent. silicon. The copper-silicon alloy begins to get so hard at about 3 per cent, silicon that it is difficult to manage. It was found by Jacobs that the addition of manganese to this alloy considerably improved the working

Jan 1, 1929

By D. W. Smith, Robert F. Mehl

It has been shown by numerous studies that the orientations of new metal crystals are determined by the orientations of the crystals in the original matrix, whether these new crystals are formed by recrystalliza-tion, by precipitation from solid solutions, or by transitions in the solid state. The orientations of crystals formed by recrystallization of cold-worked metals that bear preferred orientations are occasionally simply related to the initial preferred orientation; often, however, the relationship is not simple, but complicated and obscure in origin.1 The orientations of crystals formed by precipitation from solid solutions have been shown by many studies in this and other countries to be determined by the orientation of the crystals of the solid solution stable at the higher temperatures, though here again complicated cases have been found and no general theory is available.2 Related to this latter class are the relationships found in crystals formed by suppressed transforma-

Jan 1, 1935

By D. W. Smith, Robert F. Mehl

It has been shown by numerous studies that the orientations of new metal crystals are determined by the orientations of the crystals in the original matrix, whether these new crystals are formed by recrystalliza-tion, by precipitation from solid solutions, or by transitions in the solid state. The orientations of crystals formed by recrystallization of cold-worked metals that bear preferred orientations are occasionally simply related to the initial preferred orientation; often, however, the relationship is not simple, but complicated and obscure in origin.1 The orientations of crystals formed by precipitation from solid solutions have been shown by many studies in this and other countries to be determined by the orientation of the crystals of the solid solution stable at the higher temperatures, though here again complicated cases have been found and no general theory is available.2 Related to this latter class are the relationships found in crystals formed by suppressed transforma-

Jan 1, 1935

By V. H. Whihelm

Since 1935 California has enjoyed a remarkable cycle of discovery, which has placed the state in a very satisfactory position in regard to oil reserves. Most ol the geophysical plays have been drilled and it is possible that new discoveries must be made by the application of careful geologic and stratigraphic studies. During 1940 only one new field was discovered, which, although not of major importance, may lead to additional discoveries. During the year, 113 wildcats were drilled. New discoveries, extensions and a reappraisal of discoveries made in 1939 will not approximate over 50,000,000 bbl., as against an estimated withdrawal during the year of 224,000,000 barrels. Demand in terms of crude for 1940 was 632,000 bbl. per day as against 626,000 bbl. per day for 1939. Demand for gasoline was the same as in 1939, but the demand lor fuel oil increased 3.8 per cent. Compared with 1939, Japanese shipments decreased from 75,786 bbl, per day to 61,000 bbl. per day, but the balance of Pacific foreign shipments increased from 59,409 bbl. per day to 61,304. Total with-drawals from storage during the year will approximate 7,000,000 bbl., almost all of which is fuel oil. Drilling activity was slightly greater than in 1939 and accounted for 890 new producing wells as against 851 for 1939 (Table 3). Production averaged 611,900 bbl. per day as compared with 614.,842 bbl. per day for 1939. The productive acreage figure of the state was increased by 4000 through discoveries and extensions. New Discoveries Los Angeles Basin District Del Vdle Field.—Northwest of Newhall, where the first oil well in California was drilled, R. E. Havenstrite completed his Lincoln No. I well, flowing 390 bbl. of 50" gravity oil together with 7000 M CU. ft. of gas. Later the well was recompleted, after cutting off the gas, for 950 bbl. of 34" gravity oil. The type of structure from which this production is coming is a plunging anticline, complicated by faulting. The Lincoln No. I well uncovered approximately 180 ft. of net sand. This field contains a gas cap and its indicated productive area approximates 500 acres. An intensive wildcat drilling campaign is expected during this coming year in the district in the vicinity of the Del Valle field. Extensions and Deeper Sand Developments Los Ange1es Basin District Athens Field.—On the northwest plunge of the Athens structure, the Thorley Oil Co. completed its No. 12-1 well, flowing 250 bbl. of 3 2" gravity oil from a depth of 8097 ft. The area in which the well is located is complicated by faulting and it is impossible at this date to determine the importance of this deep-zone discovery.

Jan 1, 1941

By V. H. Whihelm

Since 1935 California has enjoyed a remarkable cycle of discovery, which has placed the state in a very satisfactory position in regard to oil reserves. Most ol the geophysical plays have been drilled and it is possible that new discoveries must be made by the application of careful geologic and stratigraphic studies. During 1940 only one new field was discovered, which, although not of major importance, may lead to additional discoveries. During the year, 113 wildcats were drilled. New discoveries, extensions and a reappraisal of discoveries made in 1939 will not approximate over 50,000,000 bbl., as against an estimated withdrawal during the year of 224,000,000 barrels. Demand in terms of crude for 1940 was 632,000 bbl. per day as against 626,000 bbl. per day for 1939. Demand for gasoline was the same as in 1939, but the demand lor fuel oil increased 3.8 per cent. Compared with 1939, Japanese shipments decreased from 75,786 bbl, per day to 61,000 bbl. per day, but the balance of Pacific foreign shipments increased from 59,409 bbl. per day to 61,304. Total with-drawals from storage during the year will approximate 7,000,000 bbl., almost all of which is fuel oil. Drilling activity was slightly greater than in 1939 and accounted for 890 new producing wells as against 851 for 1939 (Table 3). Production averaged 611,900 bbl. per day as compared with 614.,842 bbl. per day for 1939. The productive acreage figure of the state was increased by 4000 through discoveries and extensions. New Discoveries Los Angeles Basin District Del Vdle Field.—Northwest of Newhall, where the first oil well in California was drilled, R. E. Havenstrite completed his Lincoln No. I well, flowing 390 bbl. of 50" gravity oil together with 7000 M CU. ft. of gas. Later the well was recompleted, after cutting off the gas, for 950 bbl. of 34" gravity oil. The type of structure from which this production is coming is a plunging anticline, complicated by faulting. The Lincoln No. I well uncovered approximately 180 ft. of net sand. This field contains a gas cap and its indicated productive area approximates 500 acres. An intensive wildcat drilling campaign is expected during this coming year in the district in the vicinity of the Del Valle field. Extensions and Deeper Sand Developments Los Ange1es Basin District Athens Field.—On the northwest plunge of the Athens structure, the Thorley Oil Co. completed its No. 12-1 well, flowing 250 bbl. of 3 2" gravity oil from a depth of 8097 ft. The area in which the well is located is complicated by faulting and it is impossible at this date to determine the importance of this deep-zone discovery.

Jan 1, 1941

By C. E. Van Orstrand

An intrusive body is a mass of igneous rock that has migrated upward, presumably from great depths. Great variations in form, composition and depth of burial occur. It is not proposed in this paper to go into all of the details of the problem. Instead, it mill be assumed here that the intrusive has the form and characteristics represented in Fig. I. According to W. 11. Emmons minerals are not deposited in appreciable quantities below the "dead line." Important amounts of ores of virtually all metals may be found around summit cupolas, but only gold, copper and zinc (in limited quantities) are usually associated with trough cupolas. Most students of ore deposits agree that temperature changes are largely instrumental in precipitating many ores in the "hood" and that the difference in temperature between the intrusive and that of the country rock may be the chief factor in determining the mineralogy of a deposit. A problem then of some interest is to correlate the principal physical features of the intrusive with the phenomena of heat conduction as evidenced by the cooling curves and the isothermal surfaces. Mathematical Theory In order to show the possible application of heat conduction to the interpretation of the processes of metalliferous deposition associated with intrusives, it will be as- sumed that the intrusive is a large par-allelopiped of dimensions, 2l, 2m, 2n. The equation that represents the flow of heat from the parallelopiped into country rock (v = o, 1 = o), which has the same thermal properties as the intrusive, is2,3 l-x v I FT 2 [2 2 — l-x m — y — m — y n — z In this equation, the origin, x = o, y = o, z = o, is at the center of the parallelopiped. v = temperature at point x, y, z, time 1. v, = initial temperature throughout the intrusive, 1 = o. k = coefficient of thermal diffusivity. a, ß, y are variables of integration. Put n = m in Eq. I, and we have v I [2/5 [2I-x 2 — l-x m — y 2 2 2 kt 2 20xt e-a2da ebrdß

Jan 1, 1946

By C. E. Van Orstrand

An intrusive body is a mass of igneous rock that has migrated upward, presumably from great depths. Great variations in form, composition and depth of burial occur. It is not proposed in this paper to go into all of the details of the problem. Instead, it mill be assumed here that the intrusive has the form and characteristics represented in Fig. I. According to W. 11. Emmons minerals are not deposited in appreciable quantities below the "dead line." Important amounts of ores of virtually all metals may be found around summit cupolas, but only gold, copper and zinc (in limited quantities) are usually associated with trough cupolas. Most students of ore deposits agree that temperature changes are largely instrumental in precipitating many ores in the "hood" and that the difference in temperature between the intrusive and that of the country rock may be the chief factor in determining the mineralogy of a deposit. A problem then of some interest is to correlate the principal physical features of the intrusive with the phenomena of heat conduction as evidenced by the cooling curves and the isothermal surfaces. Mathematical Theory In order to show the possible application of heat conduction to the interpretation of the processes of metalliferous deposition associated with intrusives, it will be as- sumed that the intrusive is a large par-allelopiped of dimensions, 2l, 2m, 2n. The equation that represents the flow of heat from the parallelopiped into country rock (v = o, 1 = o), which has the same thermal properties as the intrusive, is2,3 l-x v I FT 2 [2 2 — l-x m — y — m — y n — z In this equation, the origin, x = o, y = o, z = o, is at the center of the parallelopiped. v = temperature at point x, y, z, time 1. v, = initial temperature throughout the intrusive, 1 = o. k = coefficient of thermal diffusivity. a, ß, y are variables of integration. Put n = m in Eq. I, and we have v I [2/5 [2I-x 2 — l-x m — y 2 2 2 kt 2 20xt e-a2da ebrdß

Jan 1, 1946

By H. J. Stehli

The first sintering of zinc ores was done at the Bartlesville plant of the National Zinc Co., under the auspices of the late Otto Rissman. Mr. Rissman, who had had a long experience in the treatment of zinc ores, well realized all the difficulties of satisfactorily roasting zinc concentrates, which were becoming finer and dustier as each year went by—thus increasing the difficulties of roasting them in the existing forms of roasters, which were furnaces of the Ropp, Hegeler or similar types. Mr. Rissman's idea of the advantages of sinter was expressed in this way: in a zinc ore dead-roasted in a mechanical furnace there are many particles that are just like an egg; that is, they have a hard and impervious film of fused material on the outside, and in the retorting this completely cuts off access of the reducing gases to the center of the egg until a temperature has been reached at which this shell of the egg can be broken down through fusion. A particle of sintered zinc sulphide, on the contrary, is exactly like a piece of sponge. The moment the retort reaches the temperature at which the reactions can take place, they begin, because the reducing gases have ready access to the interior of the particles by means of the pores of the '" sponge." His faith in the advantages of sinter was amply borne out by the results obtained at the pioneer sintering plant for zinc ores installed by the National Zinc Company. Early Method of Sintering The method of procedure at Bartlesville was to roast the zinc concentrates down to somewhere in the neighborhood of 8 per cent residual sulphide sulphur; to cool these, then to wet them down to the proper moisture and mix them in the mixer of the sintering plant; then to sinter them by means of the heat available from the residual sulphides. The sulphur contents of the roast varied considerably, of course, as it was difficult with the furnaces in use to control the roasting exactly at any point short of dead roast. Hence at times the concentrates were roasted a little too low to sinter readily, and at such times the lack of sulphur was made up by the addition of raw concentrates to the sintering-machine charge in suitable amount.

Jan 1, 1937

By K. Severin, B. Flanigan, P. Marion

“Plutonic-related” gold deposits in Interior and SW Alaska (Tintina Gold Belt) vary significantly in size, grade, vein/deposit morphology, depth of emplacement, distance from causative pluton and metal association. Metal associations such as Au-Bi and Au-As-(Sb-Hg) are a good empirical indicator of depth of emplacement and distance from causative pluton and have been used successfully in exploration. Results from a variety of analytical techniques also suggest a phenomenological cause for these metal associations, e.g. gold and bismuth have linked metallogenesis at high temperatures and thus are best correlated at deposits that are deep and/or close to causative intrusions.

Jan 1, 2000

By J Parnell, B Manson

Bitumen occurs in the basins in reservoir sandstones, in veinlets close to hydrocarbon source rocks, in veins through lava beds and in sulphide-mineralised veins where it is closely associated with, but predates, the sulphides. The role of organic matter was probably in enhancing metal reduction by creating a low-Eh environment rather than in metal transport. Coeval euhedral quartz crystals or albite in sulphide-bearing carbonate veins provide evidence of an aqueous component to the hydrocarbon fluid

Aug 1, 1995

By D Craw

The Rise and Shine Shear Zone is a mineralised low angle deformation zone traceable for at least 7 km through biotite zone schist of the Dunstan Range, central Otago. Rocks from the shear zone obtained from recent drillholes are unweathered and facilitate paragenetic studies. There is a progression of mineral deposition from semiductile foliation-parallel shearing, to subsequent folding, and brittle fracturing. Sheared rocks are dominated by microshears containing fine grained hydrothermal muscovite and rutile that has recrystallised from metamorphic muscovite and titanite respectively. Euhedral pyrite occurs within segregations in the schist and is locally brecciated by the shears.   Arsenopyrite occurs within microshears and is intergrown with hyrothermal muscovite. Fractures within relatively undeformed schist are filled with ankerite, siderite, chalcopyrite, sphalerite and galena and these veinlets also crosscut the microshears. Locally the schist is folded and zones of brecciation, silicification and vein deposition overprint the rock. Vein quartz and albite predominate and arsenopyrite and gold infill breccia matrix and crosscutting veinlets. Sulphide deposition began in the later stages of metamorphism with pyrite deposited in quartz-albite segregations. Subsequent shearing caused brecciation of some grains and accompanied deposition of arsenopyrite ¦ gold and rare sulphides along foliation-parallel microshears. Minor amounts of chalcopyrite, sphalerite and galena were then remobilised in ankerite veins that crosscut the shears. In areas of high strain, arsenopyrite was then deposited as euhedral grains in veins and breccias. Synmineralisation deformation caused the brecciation of some grains and gold was deposited infilling fractures in the arsenopyrite. The paragenetic sequence shows gold mineralisation occurred in two distinct sets of structures (semiductile and brittle) that formed at different times in the formation of the shear zone.

Jan 1, 2006

By Norman A. Jull

"Factors which affect the separation achieved in a hydrocyclone are discussed and illustrated with graphs of some mathematical relationships.Definitions of separation and sharpness include comment on use of elutriation devices.A plea is made for better evaluation of field data prior to their reporting or use in calculations. Methods of evaluation are suggested, with samples of the relevant calculations.An example of the effect of percent solids errors is given, with computer printout and plotted corrected recoveries.INTRODUCTIONThe range of interest in cyclones runs from a simple demand for classification results to a detailed study of published equations defining cyclone characteristics. Probably this group covers as broad a range and, in an attempt to offer something for everyone, I will begin with general operating comments, then move on to more analytical topics. Ideally, an author would compose his paper after the discussion period, when he would have a better idea of the areas of special interest to his audience.Sor'1e of you may share our incurable fascination with classification, especially as performed in cyclones. It is amazing that such a simple device could be in use for more than 20 years and retain as much mystery as it does. Substantial parts of the mystery have been solved but some remains, to keep up our curiosity. There is at least one valid reason: the unusual compactness of this device, which makes internal observation very difficult. What other unit can you think of which performs such a complex separation between particle sizes, shapes and specific gravities at such high capacity? Retention time in a cyclone is typically 3 seconds!Mutual Agreement - In a cyclone, every parameter of geometry and of operation interacts with every other. In an orderly discussion of individual parameters it would be necessary to repeat, in every section, 11 if all other factors are equal"". Could we agree now, for our mutual convenience, that that phrase is clearly understood between us during the remainder of this paper?"

Jan 1, 1972

By Wolfgang Gütter

India is targeting to boost its electrical capacity from 100 GW to 200 GW within the next 10 years. The National Hydroelectric Power Corporation (NHPC) has decided in2001 to take execution of the 800 MW Stage-II of the prestigious 2,051 MW Parbatihydrol electric project in Kulu district of the northern province Himachal Pradesh. Two parallel 30° inclined underground pressure shafts of 1.542m in length each will be excavated in different geological formations and lined with hexagonal concrete segments by a hard rock double shield TBM. That kind of heading will be a novelty to India and an innovative method for inclined pressure shafts. The 4.88m Mitsubishi DSTBM will be assembled underground on a swivelling steel platform especially designed for the launching as well as for the acceptance of the TBM in the upper cavern of each shaft. The hexagonal segmental lining system causes a significant higher job safety than an open TBM with conventional support. Each ring consists of four honeycomb segments with 20 cm thickness. After finalisation of the excavation a steel liner will be installed and concreted. The Joint Venture Jäger-Seli will perform the two pressure shafts as a sub-contractor for the Indian company Gammon India Ltd.

Jan 1, 2005

By M Kozikowski

The primary purpose of these investigations is to determine dewatering requirements and likely impacts associated with mining operations. Standard aquifer testing techniques were carried out at multiple locations within the Ord Range near Pardoo, Western Australia. Aquifer properties of an oxidised haematite orebody were calculated from test pumping data conducted in five fully penetrating test bores. Hydraulic properties of the Ridley magnetite orebody were calculated based on short term constant rate pumping tests, and packer tests. Packer tests were conducted in undeveloped and uncased exploration holes and diamond core holes. The new data sheds light on the hydrogeological properties of this previously unexplored region of Western Australia.Aquifer testing procedures for each bore included a preliminary step test followed by a constant rate test. Recovery data were collected in each bore over a period of four to six hours. Prior to testing, background water levels and water samples were collected in a network of monitoring and exploration bores to establish baseline water levels, gradients and water quality. Water quality within the bedrock of the Ord Range varies from 2000 to 5500 mg/L TDS whereas water quality within the alluvial sequence of the De Grey River is highly variable (400 to 2500 mg/L TDS), but is predominantly brackish with some water of potable quality which is used to supply Port Hedland. Test pumping supports the conceptual hydrogeological model that consists of a pod like orebody (aquifer) surrounded by low permeability waste rock (BIF), with very weak hydraulic connection to the adjacent alluvial systems. Calculated hydraulic conductivity from test pumping data across Pardoo ranged from 0.01 to 59 m/d, depending on deposit tested.A groundwater model was used to simulate dewatering required in proposed pits and to estimate the impact of dewatering on the surrounding shallow alluvial aquifers. Test pumping and numerical groundwater flow modelling indicate the proposed below water table pits can be successfully dewatered utilising in pit dewatering production bores. Yields from individual dewatering bores will reduce with time due to the reduction in saturated aquifer thickness.Based on the numerical groundwater modelling and field investigations the likely impacts to the adjacent De Grey River alluvial aquifer system (within the Priority 1 De Grey River Water Reserve) resulting from mining and dewatering activities is considered minimal. Recalibration of the groundwater model will be undertaken once several months of dewatering data are available.The aim of this paper is to present a range of aquifer parameters derived through standard aquifer testing techniques for an area previously unexplored in terms of hydrogeological characteristics. It is the goal of the authors to provide this comparison data set for future work in similar geologic media.

Jan 1, 2009

The purpose of this paper is to describe briefly the clean-up procedure adopted at the treatment plant of Paringa Mining & Exploration Co. Ltd. at Kalgoorlie, Western Australia.A clean-up is carried out at the end of each four-weekly period, and all figures subsequently quoted are taken from a summary of the results of the eight periods ending 8th April, 1941.STRAKING AND AMALGAMATIONOf the total gold won 22· 77 per cent. is recovered by straking and amalgamation.The discharges of both the primary and secondary ball mills are pumped over a common set of five ten feet long by three feet wide straking tables, set at an angle of 10 degrees, before passing to the 14 ft. diameter by 30 ft. by 8 ft. Dorr bowl classifier.This classifier is in closed circuit with both of the ball mills, hence the whole of the circulating load of the fine grinding circuit, which approximates to 800 per cent., is required to pass over the straking tables. For convenience in handling, corduroy cloths are used in lengths of 5 feet, and are picked up and replaced by clean cloths at four-hourly intervals. The avaHable straking area provided is, therefore, 900 square feet, or approximately 3·30 square feet per original ton per 24 hours. The density of the pulp passing over the tables is about 54 per cent. solids, the area provided per ton of pulp per 24 hours being approximately o· 2() square feet. Washing of the corduroy cloths is carried out on the day shift only, about 800 lb. of strake concentrate being obtained daily.This concentrate is sluiced from the washing trough on the elevated straking floor to the 4 ft. by 2 ft. diameter amalgamating barrel located in the gold room below.The barrel is of standard design and is rotated at 25 r.p.m. It is charged each day at 4 p.m., and grinding of the strake concentrate at approximately 70 per cent. solids is continued until 8 a.m. the following day. The barrel is then stopped, and the contents generously diluted with water, and after a few minutes rotation some of the slime is carefully poured off through the small discharge hole. This dilution and decantation is repeated until a good deal of the valueless slime has been removed.A further quantity of strake concentrate is then charged to the barrel, which is allowed a further 16 hours grinding period. After again diluting and decanting, approximately 25 lb. of mercury and 15 lb. of lime are added to the charge, which is then given an amalgamation period of 2 hours before cleaning up.By the process of grinding, diluting and removal of slime by decanting...

Jan 1, 1941

By C. E. Capes

INTRODUCTION In the coal industry, ever greater amounts of fine coal must be processed due to the need to crush to finer sizes for impurity liberation in low cost physical cleaning processes. Fine coal processing is a major problem for the industry, both through the cost of disposal of reject fines and through the mining cost of lost coal values. Of the available disposal methods, impoundment has always been the most popular. In many cases, when the coal fines were of sufficient quality, froth flotation and expensive filtration methods were used to recover the coal in these waste streams. The coal fines are not always of a marketable quality, however, and flotation, due to poor yields and difficult dewatering, has always been an expensive and not necessarily profitable process. The oil agglomeration method is increasingly important as a technology for the treatment of fine coal-in-water suspensions. These fines can be preferentially wetted and agglomerated by many different oils mixed with the suspensions. Ash-forming impurities remain in suspension and are rejected when the agglomerates are recovered, for example, by screening. Agglomeration-based methods provide perhaps the only practical means for upgrading extremely fine coal to useful products on a large scale. As with froth flotation, oil agglomeration relies on differences in the surface properties of coal and impurities to effect separation. Whereas flotation be- comes less effective with particles finer than 200 mesh (0.075 mm) or coarser than 50 mesh (0.3 mm), there appears to be no lower limit on particle size for oil agglomeration while particles % in. (3.175 mm) diameter or larger can also be treated, if desirable. In addition to this ability to clean a broader size range of coal particles, oil agglomeration can produce a dense, coarse granular product of acceptable strength and low water content without the need for vacuum or thermal drying. The preferential wetting of solid surfaces by immiscible liquids has been utilized, if not fully understood, for a long time. Indeed Gaudin,229 in tracing the ancestry of froth flotation, refers to a 15th century oil-pulp kneading procedure in which water-wetted particles were freed under water from an oiled mass. An understanding of the physical chemistry involved in such

Jan 1, 1991

By John H. Weigand, Stephen V. Crum

"VIBRONICS, INC. instrumented and monitored a residential structure for response to,blasting at aMidwestern surface coal operation. The residence was owned by the mining company and was extremely close to the operation. Blasting was conducted within 120 feet (36.5 meters) of the test structure. Up to seventeen (17), four (4)-channel seismographs were used during the monitoring period. The basement walls and floor were monitored. VIBRONICS, INC. also monitored a brick chimney in the basement and attic. Structural responses were then compared to outside vibration measurements taken in the soil near the foundation."

Jan 1, 1998

Jan 1, 1970