Search Documents

By Ralph Arnold

THOUGH production began in Canada only a short time after the discovery of oil in the United States, it has never attained large proportions, and if we were to judge entirely by the past the reserves of Canada would be put at a very low figure. There are only two areas from which oil is marketed at the present time; one, the old district around Petrolia in southern Ontario, and the other is the small Sheep Creek field near Calgary in Alberta. The former district has produced between 200,000 and 800,000 bbl. annually for the past 40 years, recent figures being near the minimum amount. Sheep Creek has produced about 12,000 bbl. annually for the past five years. The known reserves in proved territory in each of these fields are exceedingly small, when considered in terms of world reserves. The chief hope of Canada for reserves of considerable magnitude lies in the western provinces. Sedimentary rocks similar to those in the productive fields of the United States occupy thousands of square miles in the western provinces, so that it seems likely that somewhere within this great area the peculiar conditions necessary for the presence of oil pools will be found. Prospecting is being carried on energetically by several large companies, as well as by many independents. The Dominion Government, which controls most of the public lands, is pursuing a .fairly liberal policy toward the prospector, which should stimulate wildcatting; although the province of British Columbia, which controls public lands within that province, is at present unwilling to give adequate encouragement to make wildcatting attractive. As there is really no assurance that any productive pools will be found in western Canada, the estimates of reserves are subject to a wide possibility of error. In making estimates, the various areas within which geologic conditions are more or less uniform are discussed separately; the estimates given for each area are not given with the idea that there is a reasonable probability of their eventually proving to be correct. It is hoped that an average of these estimates, taken together with those made for other undeveloped countries, will give a correct total of reserves

Jan 7, 1922

By A. B. Kinzel

Advance in the art of slag control has been very rapid in the past few years. The viscosimeter method for slag-reaction rate and composition, together with the phosphorus and other methods mentioned by Dr. Herty, allow the steelmaker to rectify and control the slag in the finish period of the heat with much greater precision that ever before. However, the steelmaker's problem is more complex, and in order to make steel of proper analysis in the most economical manner the constitution of the initial slag that has formed immediately after the lime is up in the furnace is of prime importance, as it is one of the factors that determine the carbon content of the charge as melted. Many heats melt with high carbon and some with carbon much lower than is expected so that, on the average, increased furnace time is necessary before reaching the finishing period. The problem, therefore, is to so regulate the slag-making additions that a suitable initial slag will be formed at once. Where all cold metal charges are involved, particularly where the iron and scrap are selected, this may be done with a fair degree of regularity. This regularity results not only in better conditions at the beginning of the heat and during the carbon drop, but also the need for smaller slag-modifying additions toward the end of the heat. The above has been well demonstrated by the work reported by Reagan in the past few years. Where large amounts of cold pig or hot metal are used, the problem becomes more involved. It is much more difficult for the steelmaker to be sure that for any given furnace the heat will form the desired initial slag. Observations of many heats indicate that the pig iron is a dominating factor in the constitution of the slag formed. The scrap is also a factor but in general could be roughly classified and a correction made therefor. The necessity, therefore, arises for a method of correlating the pig-iron charge and type of slag formed for any particular furnace, which resolves itself into a measure of those qualities of the pig iron which affect the slag. The amount of silicon, manganese, phosphorus and sulfur in the pig iron will probably have some effect on the type of slag formed, but

Jan 1, 1935

By A. B. Kinzel

Advance in the art of slag control has been very rapid in the past few years. The viscosimeter method for slag-reaction rate and composition, together with the phosphorus and other methods mentioned by Dr. Herty, allow the steelmaker to rectify and control the slag in the finish period of the heat with much greater precision that ever before. However, the steelmaker's problem is more complex, and in order to make steel of proper analysis in the most economical manner the constitution of the initial slag that has formed immediately after the lime is up in the furnace is of prime importance, as it is one of the factors that determine the carbon content of the charge as melted. Many heats melt with high carbon and some with carbon much lower than is expected so that, on the average, increased furnace time is necessary before reaching the finishing period. The problem, therefore, is to so regulate the slag-making additions that a suitable initial slag will be formed at once. Where all cold metal charges are involved, particularly where the iron and scrap are selected, this may be done with a fair degree of regularity. This regularity results not only in better conditions at the beginning of the heat and during the carbon drop, but also the need for smaller slag-modifying additions toward the end of the heat. The above has been well demonstrated by the work reported by Reagan in the past few years. Where large amounts of cold pig or hot metal are used, the problem becomes more involved. It is much more difficult for the steelmaker to be sure that for any given furnace the heat will form the desired initial slag. Observations of many heats indicate that the pig iron is a dominating factor in the constitution of the slag formed. The scrap is also a factor but in general could be roughly classified and a correction made therefor. The necessity, therefore, arises for a method of correlating the pig-iron charge and type of slag formed for any particular furnace, which resolves itself into a measure of those qualities of the pig iron which affect the slag. The amount of silicon, manganese, phosphorus and sulfur in the pig iron will probably have some effect on the type of slag formed, but

Jan 1, 1935

By J. J. Bodmer

THE substances or materials employed in this manufacture, are the same as those used in the preparation of mortar and concrete, viz., the different kinds of lime and sand. Instead of, or in conjunction with, sand there may be used calcined clay, blast-furnace slag, clinkers or ashes from furnaces, natural puzzolana, powdered chippings from stone quarries, etc. Of the different kinds of sand, pit-sand-siliceous sand, as it commonly occurs mixed with gravel-and the sand found on the seashore, where the salt has been washed out by long exposure, whilst out of reach of the tide, may be used. The purer the above-named materials are from admixtures of clay, earth, or organic substances, the more complete will be their combination with the lime, the quicker will the manufactured brick or block set, and the more satisfactory will be the quality which it ultimately attains. For this reason, subdivided blast-furnace slag is preferable in most cases to sand, and the only sand which, in reference to setting capacity, is analogous to blast-furnace slag, is the volcanic sand occurring in different localities in North and South Wales, as an almost pure calcined silica. The lime used for the manufacture may be either slaked or unslaked. In the first case, (slaked), in order to obtain satisfactory results, the lime must be strongly hydraulic. The use of unslaked lime, however, is by far preferable. A process for using fresh or unslaked lime has been patented in England by Major-General Scott. Lime thus prepared is called " selenitic lime," and consists of a mixture of fresh (un¬slaked) lime with sulphate of lime, or plaster of Paris. The gray-stone lime, for instance, found by the Medway, is mixed with from 5 to 7 per cent. of plaster, which has the effect of keeping the lime from slaking when water is added. This mixture also partakes of the nature of cement, and when used for mortar, or concrete, attains in a shorter time a greater degree of hardness than the same lime would ever have obtained after being slaked. Bodmer's process for the manufacture of artificial stone bricks consists chiefly in the use of automatic measuring, forwarding, and mixing apparatus, by means of which the materials are supplied and unite in a continuous stream, and are accurately measured. They

Jan 1, 1874

By R. S. Shoemaker, F. W. McQuiston

REFINERY SECURITY "Highgrading, " a polite word for stealing gold and silver, has been a way of life since the metals in native form have been mined or produced. Unfortunately, in the past, highgraders were not always severely prosecuted or even looked upon unfavorably in their communities. Recent high metal prices with attendent world wide publicity, however, has made highgrading or thievery again a serious problem in mines and plants. When a small button of gold the size of the end of ones little finger has a value equal to about one week's wages, the safe-guarding of gold production by enforcing tight security measures becomes a prime responsibility of management. The higher the gold price, coupled with unrestricted owner- ship, the greater the temptation to “get-your-cut”, and diligence by management must become an integral part of plant security. Primary security begins by knowing the expected gold production and the sampling of a gold ore mill feed for this determination has proved not reliable. However, solution flows can be accurately sampled and measured thereby closely predicting the gold recovered each day as precipitate. The progressive record of total ounces of gold contained in the precipitation press, referred to in cyanidation plants as I1solution calll1 predicts the accumulated production. The "callH is an important adjunct to security and extreme caution must be used so that the pregnant solution meter and sample are confined in a security area. It should be recognized that this key sample may be the target for Ifdoctoring" by trusted insiders (assay office employees) as a preliminary step for stealing precipitates and/or metal. Security measures similar to the following were adopted after one operation experienced a sizeable theft of gold precipitate and metal by trusted employees. The refinery area where precipitates are handled and melted to bullion and all other gold products are kept should be completely enclosed with a tight security fence preferably of solid construction. Access to this enclosure should be through one of two electrically controlled gates, one for personnel and another for occasional truck entrance. Admittance should be restricted to essential personnel who are required to sign a register in and out with the date and time. I£ there is a "back gate" to the restricted fenced area, it should remain locked except in an emergency and then opened only by a supervisor. Television monitoring cameras viewing the gate entrance and other sensitive areas connected to a viewing screen located in the general office afford visual observation at all times.

Jan 1, 1975

By T. Prof. Egleston

ALL industrial establishments whose operations depend upon chemical reactions use gases. In the simplest case the oxygen of the atmosphere, heated or not, as the case may be, is used, and in other cases, gases which are produced by a special apparatus of more or less complex composition. The manufacturer depends, for the success of his operations, entirely upon having these gases arrive at the right time, in the proper proportions, at the required temperature. It often requires but a slight variation in their composition to make a given process a success or a failure. In most cases the gas used is formed from fuel, and according as variations in its composition are produced by alterations in the manner of charging the grate, not only different, but often directly opposite, results are obtained. The great industrial question of the present time, and one upon which the prosperity of the world depends, is how to get the greatest amount of useful effect from fuel, whether the caloric is used directly or is transformed into horse-power. In almost all industrial pursuits this translates itself into the question of how to construct a fireplace and its adjuncts in such a way that the heat of the flame and of the products of combustion shall be made to produce a maximum effect. Unfortunately, until very recently, except by comparison, there was no means of ascertaining whether the loss of useful effect was 80, 40, or 20 per cent. of the total amount of fuel employed. It seems now strange that there should have been furnaces so constructed as to produce 20 per cent. of carbonic acid in the fireplace, but this has been proved by analysis to have been true. It does seem incredible that, notwithstanding the immense number and variety of furnaces used for different processes, and the great difference in kind, quality, and quantity of fuels consumed, there should formerly have been used for them all, the same stereotyped fireplace, varied only in its dimensions of height, length, and breadth. It is true that, with a good fireman, excellent effects may be, and have been, produced, but the manufacture is here, as in many other cases, dependent on the intelligence of the workman, a very uncertain reliance for capital to rest upon. The workman, unless he receives a prime for fuel saved, or is fined for excessive use of it, may be said

Jan 1, 1874

R. Schuhmann, Jr. (Purdue University)— Fulton and Chipman's results on rate of silica reduction from slags are analogous in many was to the results of Parlee, Seagle, and Schuhmann10 on rate of alumina reduction from alumina crucibles. Both investigations have given comparably low rates of reduction and slow approaches to equilibrium. Accordingly, we may hypothesize that the rate-determining step is the same in both kinds of experiments; that is, oxygen diffusion across the stagnant boundary layer on the liquid-metal side of the interface between the liquid metal and the oxide phase (slag or solid oxide). I suggest that silica reduction involves the following consecutive steps: I) At the slag-metal interface: SiO2(slag) Si+ 20 II) Transport of oxygen from slag-metal to gas-metal interface: a) diffusion across liquid-metal boundary layer at slag-metal interface. b) convection within the body of liquid metal. c) diffusion across boundary layer at metal-gas interface. 111) At the metal-gas interface: C +O- CO (gas) Iv) At the graphite-metal interface: C (graphite) -C At steelmaking temperatures it is reasonable to assume that equilibrium is attained in all three chemical reactions (I, 111, and IV) right at the respective interfaces. Convection within the stirred liquid metal (step IIb) is also rapid. Transport of Si and C should be orders of magnitude easier than transport of 0, because of the relatively high concentrations of Si and C. Accordingly, we might expect the overall reaction rate to be determined by boundary-layer diffusion of oxygen, either IIa or IIc. Fulton and Chipman's demonstration that bubbling CO through the system had no major effect on reaction rate indicates that IIc is not the slowest step. Therefore, it becomes logical to estimate the maximum rate for step IIa and to compare this theoretical estimate with Fulton and Chipman's experimental data. If oxygen diffusion across the liquid metal boundary layer at the slag metal interface (step IIa) is rate-determining, In this equation, dn sio, /dt is the rate of silica reduction in moles per sec,A is the area of slag-metal interface in sq cm, Do is the diffusivity of oxygen in sq cm per sec, 6, is the boundary layer thickness in cm, c,* is the oxygen concentration right at the slag-metal interface in moles per cubic cm, and co is the oxygen concentration in the body of the liquid metal, also in moles per cubic cm. Equilibrium data" on the silicon deoxidation reaction in liquid iron and steel at 1600°C indicate that the oxygen contents of the liquid metal in Fulton and Chipman's experiments at 1600°C probably fell in the range of 0.5 x10-3 x10-3wt pct. That is, the maximum conceivable value of co*-co for the system under consideration was on the order of 10"5 mole oxygen per cubic cm. On the basis of previously published data,1O,11 it is estimated that Do/0 will fall somewhere in the range from 10-3 to 10-1 cm per sec. The surface area A in Fulton and Chipman's experiments was approximately 20 sq cm, and the weight of metal involved was about 500 grams. Combination of all these figures with the above rate equation leads to an estimate that the rate of silica reduction should fall within the range from 0.002 to 0.2 wt pct Si per hr. This estimate is consistent with the experimental data. For example, Fulton and Chipman's Fig. 2 shows a change of about 0.3 pct Si in 10 hr, corresponding to an average rate of 0.03 pct per hr. According to the proposed hypothesis, increasing the temperature will increase the reaction rate ill two ways: 1) by increasing oxygen diffusivity and 2) by increasing the oxygen concentration (oxygen solubility) in the liquid metal. The combination of these two effects accounts for the high value of the observed activation energy. Summarizing, I propose that the rate of silica reduction, like that of the carbon-oxygen reaction, is diffusion controlled and that low oxygen concentration in the liquid metal is the major factor accounting for the very low observed rates of silica reduction. John Chipman (author's reply)—The authors thank Professor Schuhmann for his interesting contribution. His proposed explanation may well prove to be the correct one. There is clearly a need for much further experimental work on this problem, and further research is in progress.

Jan 1, 1961

At its meeting on February 21, 1933, the Board of Directors passed the following resolution defining and expressing the policy of the Institute with respect to official participation or action in controversial matters: WHEREAS, the Board of Directors at its last meeting. passed the following resolution: "The Board of Directors, having been appealed to by several Local . Sections for advice concerning the attitude and policy of the Institute relating to the endorsement of candidates for public office, the following statement of policy is formulated:

Jan 1, 1937

By Lap-yan Chan

Chan and Goodman (1983) presented a procedure for simulating joint traces and identifying key blocks on an excavation. This paper defines six measures of support requirements that characterize the number and dimensions of key blocks, taking into account the frictional properties of joints and actions of support systems. When correlated with case histories, these measures of support requirements can help in choosing an optimal design for shallow excavations in discontinuous hard rocks.

Jan 1, 1984

By L. C. Reese

The ultimate resistance against a rigid cylinder which is moved laterally in a cohesionless soil is a function of the geometry of the cylinder and the properties of the soil. An approximate method is developed for computing this resistance and is tested against results of laboratory experiments. Satisfactory agreement between the method and experiment was obtained. Not only was the ultimate resistance against the cylinder measured, but measurements were made of the shape of the rupture surfaces. These measurements should allow the development of a more rigorous computation procedure. INTRODUCTION A critical aspect in the design of offshore drilling platforms is assuring the stability of the platform during a hurricane. The large horizontal loads from waves and wind make a severe loading condition. Piles are generally employed as the foundation since they can be effective in resisting both horizontal and vertical loads. Spuds are sometimes used with a mat foundation, where the spuds are designed principally to resist horizontal loads and the mat designed principally to resist vertical loads. The research reported in this paper is related to one aspect of the problem of laterally loaded piles or spuds in sand. The complete solution to the problem of the laterally loaded pile in sand would require the prediction of soil resistance against the pile as a function of pile deflection; only the ultimate resistance against short piles is considered in this paper. A considerable amount of additional research will be necessary in order to obtain a complete solution to the problem of the laterally loaded pile in sand; however, the work reported here should be useful as a guide in the performance of some of the additional research. ULTIMATE LATERAL RESISTANCE AGAINST A LONG FALL IN SAND To aid in the understanding of the theory which is developed for a cylinder, the theory for earth pressure against a wall is reviewed. In Fig. l(a), a long wall of height H is shown embedded in soil. Soil resistance will develop as the wall is deflected, and the soil resistance will increase with deflection until some limiting value is reached. In this discussion, and those following, it is assumed that all points on the wall deflect equal amounts. A possible shape of the real curve which relates soil resistance to deflection is shown by the dashed line in Fig. l(b); however, as a means of simplifying the discussion, an idealized curve (shown by the unbroken lines) is drawn. If such a wall as this were furnishing the horizontal support for an offshore structure, the dashed curve in Fig. 1 would be the information needed in performing a foundation analysis, with the idealized curve possibly being an acceptable substitute. For the idealized curve, the soil resistance is linear with deflection for the early portion of the curve such that

* Phosphate from the Maiden Rock deposits in the Missouri River Basin, Mont., are to be developed by the Victor Chemical Works of Chicago. A $5 million plant for processing the rock into elemental phosphorus is to be constructed in the vicinity of Butte. The plant will receive power from the Bonneville Power Administration. * Tests are being made to determine whether iron pellets from taconite concentrates will boost blast furnace and open hearth output at the Campbell Works of the Youngstown Sheet & Tube Co. About 35,000 tons of iron pellets have been shipped from Minnesota for this purpose.

Jan 2, 1951

By George Haworth

ELECTRICAL illumination of shafts, stations, and haulageways has been successfully practiced for many years, but its use in drifts and stopes where mining operations are carried on has- been limited. The large underground drifts of the Tri-State field present a lighting problem that is not satisfactorily solved by the use of the carbide lamp. It has, for some time, been the policy of the Anna Beaver mine to provide ample lighting throughout the underground haulage drifts and working faces. This has, in the

Jan 6, 1928

The volumes of Transactions, which are published annually, contain the list of officers, rules, etc., the Proceedings, and the papers revised for final publication. (In this revision, after the preliminary publication, authors are permitted to use the largest liberty; and the changes and additions made in papers are sometimes important. It should be borne in mind by those who study or quote a paper in the preliminary edition, that they may not have in that form the ultimate and deliberate expression of the author's views. It should be added, however, that in the majority of cases there are no important changes.) These volumes are for sale as follows, in paper covers:

Jan 1, 1917

The annual report of the Secretary of the Southern California Local Section for the year ending May, 1919, says that the Section was called upon to give all the assistance possible for the different Liberty Loan drives, for the Red Cross drives and not only in the canvass of our membership, but the canvass of all of the mining companies represented in this city. The committee on the Red Cross drive on which we were represented raised a larger proportion of the total amount than any other in the city. The subscriptions for Liberty Bonds from the members of our' Section that were credited to the Committee of the Joint Technical Societies exceeded in amount the subscription from the members of all the other technical societies combined. Members of our Section slid splendid and efficient work throughout the first half of the year at the Red Cross headquarters in this city, and under the leadership of A. B. W. Hodges and F. B. Close, systematized the work of handling the enormous quantity of material that passed through that organization. Mr. E. A. Montgomery directed the canvass of the mining companies of this city in the bond drives, and the Executive Committee did its part in solicitation among the mining engineers. The Section, together with the local sections of the American Chemical Society, American Institute of Architect, American Institute of Electrical Engineers, American Society of Civil Engineers, American Society of Mechanical Engineers, and the local Engineers and Architects Association, forms what is called the Joint Committee of the Technical Societies. of Los Angeles. The honor of having the first president of this combined organization of engineers was given to us with, the election of Mr. Seeley W. Mudd. Upon Mr. Mudd's entering the service, Mr. George A. Daman of the Electrical Engineers was elected to the position and served splendidly during the latter part of the year. It devolves upon this Section to be represented upon this Joint Committee by three members, and it is our duty to supply a speaker once in six weeks to address the engineers in attendance at the weekly luncheon. During the year not a few of the most prominent men of the engineering professions have spoken upon subjects of the greatest interest to us all. Had it not been for the organized team work in the engineering profession available through this Joint Committee, there would have undoubtedly been passed in the recent session of the legislature of this state a bill for licensing and registering all professional engineers in this state, which, in the opinion of your Executive Committee and a large proportion of the membership of this Section, would have fallen far short of either protecting the engineer or protecting the public from impostors. That the public is awakening to the importance of what our National Society represents in the profession of mining engineering can be well inferred from the increasing number of inquiries your Secretary receives regarding the reputation of mining engineers. The necessary qualifications which a membership in the Institute requires and the membership of an engineer in this National Organization is more and more a criterion as to the ability of an engineer who represents himself as such, to the general public.

Jan 9, 1919

Objective stockpile goals have been met for antimony, bismuth, fluorspar, and iridium, while those for bauxite, cadmium, copper, lead, zinc, manganese, mercury, platinum, tin, and vanadium have not, according to a report by the Munitions Board. Total materials under inventory and contract represent about 78 pct of entire stockpile goals, the report stated. Frobisher, Ltd., of Canada has been given permission to survey power possibilities in certain lake and river basins in the Yukon believed to have a potential of 5 million he. Canadian Resources Minister, Robert Winters, also announced that his Government has rejected a bid by Aluminum Co. of America concerning use of Canadian waters to power a proposed Alaska aluminum project. Alcoa is reported hopeful of resuming negotiations.

Jan 3, 1953

POSITIONS VACANT (Under this heading will he published notes sent to the Secretary of the Institute by members or other persons.) Mine and mill accountant for Mexico. Knowledge of Spanish desirable. Salary $150 to $200 gold per month with living quarters. No. 60. Master mechanic familiar with mine and cyanide plant machinery for Mexico, $200 gold per month and living quarters. No. 61. Electro-metallurgist for production of ferro-alloys, salary $200 to $400 depending on experience. No. 62. Man familiar with ferro-tungsten products of electric furnaces to draw up specifications for machine tools, to watch these tools in service and revise specifications accordingly. Salary $150 to $200 per month. No. 63. Man to take entire charge of the sales of a steel company making electric alloy steels in the shape of ingots, billets and bars. To the right man an opportunity will be offered for taking a leading position in the management of the company and of participating in its results. No. 68. Chemist wanted by Electric Steel concern in the East. Must be fully acquainted with alloy steel analysis. Send full particulars and references. No. 73.

Jan 3, 1916

By S. F. Radtke, J. A. Snyder, R. M. Scriver

An automatic, continuous casting arc furnace employing a nonconsum-able electrode and a direct current arc has been constructed and operated successfully for titanium. A comparison of the properties of arc and induction-melted titanium indicates that where high ductility, formability, and toughness are required, arc-melted metal is preferable. BECAUSE of the reactivity of titanium metal with all known refractories and the common atmospheric gases, melting of the metal presents numerous problems. It is necessary to provide an inert atmosphere in the furnace as well as a crucible material that will not react with the molten metal, if a ductile ingot is to be produced. Two special furnaces have been developed that meet the requirements and one, the induction heated graphite furnace, has been described in some detail.' Little information is available for sizable units wherein power is applied to the melt through an arc, and the dearth of technical information on such a furnace prompted this report. It has been demonstrated clearly that arc melting produces titanium metal with superior toughness, ductility, and formability. To produce titanium ingots with these properties, an automatic, continuous casting arc furnace has been developed and is described herein. The history of arc melting may be traced to 1800, when Sir Humphrey Davy2 first experimented with Volta's electric battery and found that light could be produced and an arc formed between two carbon points attached to the cell. The discovery of the arc was followed by the design and construction of an arc furnace by Napier," in 1845, for the reduction of metal oxides. In 1853, Pichou' described a similar furnace, although it was not until the discovery of the dynamo in 1867 that the arc furnace could achieve commercial significance. In 1878, Siemens- esigned the first arc furnace intended for the melting of metals and by 1882 had melted steel and platinum successfully. . This was followed by Moissan's" classical work with the arc furnace in 1892. W. von Bolton,' in 1905, found that the arc furnace was suited admirably for melting refractory metals. In his work with tantalum, no suitable refractories for retaining the molten metal were found to exist. Together with Otto Simpson, he developed an arc furnace with a water-cooled copper crucible in which tantalum could be melted without contamination. This technique proved eminently successful. In his paper on the preparation of ductile titanium, Krolle first described an application of the von Bolton furnace to the melting of this metal. The

Jan 1, 1952

By Peter J. Huck, Madan M. Singh

IIT Research Institute has investigated the potential of high pressure water jets for rapid rock excavation. During this study, an attempt was made to correlate the extent of breakage effected to the mechanical properties of rocks. Six rock types were used in these experiments and nine properties were determined for each rock variety. A regression equation using the two most significant rock properties and one jet parameter (pressure) was established. Although tests were conducted to specific pressures of 35, no minimum in the specific energy consumption was noted.

Jan 1, 1971

By Carl R. Davis

The cost of mining during the past history of these mines has been excessive, principally by reason of the inefficiency of labor under the wage-system. The amount of labor performed per man was unsatisfactory; and Mr. Edmund B. Kirby, the general manager, decided to adopt the contract-system as a remedy. For this purpose the method now in use was devised by the writer (then and now the superintendent), as best adapted to the local conditions. On March 12, 1900, this system was presented to the miners of the War Eagle and the Center Star. The issue remained unsettled for several weeks,

Jan 1, 1902

By Orville R. Lyons

THE continuous vacuum filter, whether it be a vertical or horizontal disk, inside or outside drum, when properly applied is a very effective device for dewatering fine solids. Because of the number of variables that affect its performance, however, it is not possible to obtain consistently maximum moisture reduction in an operating plant. This paper presents a method for determining the average cake moisture and the variations in cake moisture to be anticipated when dewatering fine solids by continuous vacuum filters under normal operating conditions.

Jan 10, 1951