Search Documents

By U Briem, R Verreet

The level of wire rope technology used in mine hoisting applications has a significant effect on the overall efficiency of the hoisting system. This paper discusses the effect that a reduction in rope mass per unit length and an increase in rope breaking strength can have on rock skip capacity and hence mine shaft output. A 20 per cent reduction in rope mass per metre for a typical 48 mm hoisting rope, while maintaining the breaking strength, increases the skipÆs capacity by circa 30 per cent at a suspended rope length of 3000 m. Such gains in shaft output, without any significant changes to the shaft or winder design, can have major implications for the feasibility of future deep mine projects. The technical challenge for rope manufacturers is how to get rid of 20 to 30 per cent of the rope mass while keeping the breaking strength and modulus of elasticity of the whole rope constant. CASAR are currently developing steel wire rope constructions where the steel IWRC has been replaced with high strength, high modulus fibres such as Kevlar«, Spectra« and Dyneema«. One of the key aspects of such composite rope designs is to ensure equal load sharing between the different rope components, ie in proportion to their area. If there is a significant difference in modulus between the fibre core and the steel outer strands, the core may not carry its proper proportion of the load and the outer strands would be overloaded. Some technical aspects of the design of composite steel wire ropes are discussed. A design and operational issue that needs careful consideration is the safe non destructive testing (NDT) of composite ropes. Traditional magnetic NDT would only be capable of inspecting the steel wires. Techniques therefore need to be developed that would give operators a reliable indication of the condition of the load bearing fibre core. This paper also discusses possible solutions to this very important NDT question.

Jan 1, 2005

By R Pie, J Crusius, P Whittle, J J. McNee

The Main Zone and Waterline pit lakes at the Equity Silver Mine near Houston, BC (Canada) are the sites of an ongoing three-year government- and industry-funded research program. In order to assess the feasibility of various bio-remediation strategies, field-scale manipulations were conducted using enclosed mesocosms (limnocorrals). Two manipulation strategies were tested: addition of algal nutrients (phosphate and nitrate) to Main Zone Pit surface waters; and addition of algal nutrients (surface waters) and dissolved organic carbon (deep waters) to the Waterline Pit. Nutrient addition was conducted in order to stimulate algal production and enhance metal scavenging by biogenic particles, while dissolved organic carbon (ethanol) was added to increase oxygen demand and foster the development of sulfate reduction in pit bottom waters. Fertilisation resulted in rapid growth of natural phytoplankton populations in the surface waters of both pits. In the Main Zone Pit, the stimulation of algal growth resulted in the pronounced removal of both dissolved and total metals (Zn and Cu) from surface waters, with higher rates of metal removal being observed at higher nutrient additions. Metal removal could be attributed to the scavenging of dissolved metals by biogenic particles and subsequent particle settling. A similar pattern of removal from surface waters was observed in Waterline Pit (Zn and Cd). The addition of ethanol to deep waters in Waterline Pit was effective in promoting sulfate reduction in the lower layer. The development of reducing conditions resulted in near-quantitative removal of dissolved Zn and Cd, presumably as secondary metal sulfides. Iron, As and Ni profiles in Waterline Pit exhibited no evidence of removal from either surface waters or bottom waters. Collectively, the results demonstrate that the passive forms of bioremediation tested in these pit lakes may be effective for whole pit-lake remediation.

Jan 1, 2003

By V. F. Marsters

Peru has produced petroleum since the early seventies, the first work being in the Zorritos field, in the Province of Tumbes, adjoining Ecuador. In the early nineties, the Negritos field, in the Department of Piura, came into prominence, and by 1905 had attained an annual production of 335,160 bbl. The early development of the field was under the general direction of the London & Pacific Petroleum Co., but it is now handled by the International Petroleum Co. In 1900 and 1901, the Lobitos field became the scene of marked activity. In 1905, its total production amounted to 75,000 bbl.; it has continued to increase as has Negritos. From 1897 to 1902, there was prospecting in the region of La Brieta (or Fernandez), on the Mancora River, about 25 to 30 km. from the coast. Small production of a heavy oil was obtained from three different sands. So far as the author knows, no work has been done in that locality since 1902. There are thus four distinct fields in the north endof the Peruvian coastal plain. The, remaining productive locality of Peru is the Pirin or Pusi field, at the northwest end of Lake Titicaca, Department of Puno, in southern Peru. The first prospecting near Pusi was done by Brown Brothers, of Los Angeles, Calif., who obtained modest production about 1906; according to reports, activities ceased about 1914 or 1915. The maximum annual production was obtained about 1908, estimated at 76,000 barrels. Peru possesses two distinct geographic provinces in which we may look for the development of a larger oil industry; namely, the coastal plain province, and the inter-Andean plains.

Jan 7, 1922

By M. A. Rigdon, R. E. Grace

The dissociation of cupric oxide to cuprous oxide and oxygen was studied with a microbalmce technique at 700" to 750°C. In this temperature range the dissociation pressure of the reaction 2CuO= Cu2O + 1/2 O2 was: The theory of near-equilibriwm reaction rates predicts a linear relationship between reaction rate and the Gibbs free-energy change for small values of AF/RT. This correlation is found to be valid for AF/RT = -0.1 or approximately 200 cal per mole away from equilibrium. THE theory of reaction rates near equilibrium as developed from classical thermodynamics suggests a small range of linear behavior between the overall reaction rate and the free-energy change accompanying the process. The extent of this linear correlation is generally unknown, even to the order of magnitude. The idea of linearity is also found in the formal mathematics of coupled transport phenomena, e.g., chemical diffusion, thermal diffusion, thermoelectricity, and so forth. The linear array of forces and fluxes which leads to various main and cross coefficients is predicated upon linearity between reaction rates and the bulk thermodynamics which govern the process. The general case in reaction kinetics is well-known: the magnitude of the free-energy change does not cor- relate with observed reaction kinetics, irrespective of whether the process occurs by diffusion or chemical reaction or both. The real need is to investigate specific reaction paths near equilibrium in order to learn of the limitations in attempting to correlate reaction rates and thermodynamics. It is the main purpose of this paper to examine the dissociation kinetics of cupric oxide under conditions of known driving force where the dissociation process is likely to occur by chemical reaction. A secondary objective is to obtain equilibrium data for the CuO-Cu20-O2 system. In a prior paper Edmiston and race' investigated reduction kinetics of wustite in H2-H2O gas mixtures. The present study was carried out in oxygen according to the following reaction:

Jan 1, 1969

By J. F. Crouch

INTRODUCTION Roll front uranium has unique geologic characteristics (L,) which require specialized mining procedures. Roll front uranium occurs in arkosic sandstones with the ore zone typically less than 100 feet in thickness with up to 400 feet of overburden. The areal extent of ore is often a few thousand acres. Within the ore zone, ore grade material occurs in C and S shaped rolls, which are a few feet in width and height but may run laterally for several hundred feet. Since the total mine plan may include mining all ore, a roll front uranium mine may cover a few thousand acres. For both economic and environmental reasons, a roll front deposit is mined as a series of phases or sub-pits (3, 4) as illustrated in Figure 1. A typical sub-pit is 400 to 500 feet across. Sub-pit 1 is stripped initially and the overburden is spoiled on the surface. Depending on haul distance and overburden characteristics, stripping is done with trucks and shovels (or front-end loaders) or scrapers. When ore is encountered in sub-pit 1, mining begins, and the stripping equipment is moved to sub-pit 2, with sub-pit 2 overburden also being spoiled on the surface. When ore is encountered in sub- pit 2, sub-pit 1 mining should ideally be complete so the mining equipment can move to sub-pit 2 and sub-pit 3 overburden can be spoiled in the mined out sub-pit 1 area. Ore is mined selectively in a series of 12 to 24 inch cuts by a 2-1/2 yard backhoe on the basis of radiometric probing. For effective drainage, ditches must be maintained on the boundary of sub-pits, and mining lifts are kept as level as possible, with the orebody slightly elevated as part of general good mining practice. Waste removal in the ore zone is done by self- loading scrapers near the orebodies and by push-pull or push loaded scrapers away from the orebodies. Each self-loading scraper cut is

Jan 1, 1983

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 S. J. Hubbard, S. D. Michaelson, A. W. Last, B. H. Ensign

Of the seventeen western states, five-Arizona, Utah, New Mexico, Montana, and Nevada-produce about 90 pct of this country's primary copper. All seventeen of these states occupy 60 pct of the nation's land area but receive only 25 pct of the country's total precipitation. Seventy percent of this precipitation returns directly to the atmosphere through evaporation and transpiration, leaving very little for ground reservoir recharge or immediate domestic, agricultural, or industrial use. With so limited a supply available for all, competition for water rights among users is severe. The result does not always permit using the limited supply to produce the most valuable end product. Most of industry and much of agriculture can shop around for suitable operating locations. Where water is critical to their purposes, they can and do locate in areas where the needed amounts are available. Such is not the ordinary lot of the mining industry, which must locate in the area of the deposit it is planning to mine and concentrate. In the case of copper this happens to be, for the most part, right in the heart of the semi-arid regions of the West.

Jan 7, 1960

By Fred A. Krafft

The time allotted to this paper will permit only the sketching of general principles and practice as generally employed in the industry to maintain and preserve the physical well-being of the miner and his family. Let it be emphasized on behalf of the industry that coal opera- . tors, individually and collectively, have given primary consideration to the appointment of a mine or community physician who is charged with the responsibility of caring for the sick and injured. However, it too frequently happens that with the selection or appointment of the camp doctor many operators wash their hands of further responsibility toward the health and the working efficiency of their employees. The coal industry is so organized in most of the coal-producing areas that not only is the health of the individual miner an important production problem but the collective health of the entire mining community is a fundamental operating problem. This is particularly demonstrated when epidemics of communicable diseases attack entire communities, with resultant loss of life and production and general community distress. The problem and responsibility of maintaining high health standards among miners and their families should be given as much consideration as safety, economical production and efficient distribution are given in the successful operation of coal mines. Company Policy In the inauguration or administration of a medical program for a large mining operation or for an individual mine, the first question to be solved is what the company policy is to be with respect to the following factors pertinent to a medical program: 1. On what basis will the company and the employees finance the program ? 2. Should a contract doctor or a full-time doctor on salary be employed ? 3. What measure of service is to be rendered the employee and his family in return for his monthly contribution to the medical program?

Jan 1, 1936

A major factor in the economic development of New South Wales has been the ready availability of coal for the major industrial and urban centres of Sydney, Newcastle and Wollongong. Historically, the presence of high quality coal near these areas has acted as a catalyst to urban and industrial growth. This easy access to low cost coal resources over the past 200 years has given rise to a commonly held belief that New South Wales contains vast coal resources sufficient to meet any foreseeable demand. However, a recent study undertaken by the Coal Resources Development Committee has found that New South Wales is likely to face a serious shortage of economically mineable coal in the future. Forecasts predict that demand for New South Wales coal will increase by about 40 per cent, and then remain at about that level for at least a further ten years. To meet such demands, the coal industry will require access to economic high quality coal resources.

Jan 1, 1995

By Zhongxue Li, Wenguang Li, Yiqing Zhao, Shuaiqi Wang

"Faced with the serious managerial situations and diverse conditions and needs for mine safety, occupational health and environmental stewardship in Chinese mining communities, an evidence-based approach is proposed for the management of mine safety, health and environment integrity. By the proposed approach, tangible and effective scientific evidence should be collected and accumulated, and the authenticity, accuracy and applicability of the evidence should be assessed to form an evidence-based approach for characterizing mine safety, health and environmental hazards and risks from multidimensional perspectives. The results are then used to formulate diverse safety, health and environment functional requirements. In an evidence-based approach, the evidence is combined with the professional experiences and the actual economic and technological situations, availability and affordability of a mine. This approach is helpful to establish scientific, reasonable, acceptable and effective solutions for identifying and mitigating hazards and improving the level of mine safety, health and environment integrity of mining operations.Introduction / Background In recent years, economic reforms have opened China's economy so that Chinese society has rapidly modernized. Along with this advancement, the exploitation and utilization of mineral resources continues to be active and the scale of mining production continues to increase, which has created a deterioration in resource reserves and as well as the general condition of mining technology. There are many hazards and safety problems in mine production and occupational health as well as in the community environment in China’s mining industry. These problems threaten the security of China's mines and present serious obstacles and challenges to the industry and the government. According to the statistics from the State Administration of Work Safety Supervision, there were 50,500 mine safety incidents in China between 2001 and 2013, which consisted of 31,439 coal mine safety accidents and 19,061 non-coal mine safety accidents, resulting in 30 deaths (Qin 2014). At the same time, mineral dust and radioactive material from mine production processes have increased the morbidity rate of silicosis and cancer in mining workers."

Jan 1, 2017

By Weir D. R, Doyle B. N

The Sherritt Zinc Pressure Leaching Process is based upon the direct pressure leaching of zinc sulphide or lead-zinc bulk sulphide concentrates to produce zinc sulphate in solution and elemental sulphur in the leach residues. The zinc sulphate solution is compatible with conventional purification and electrowinning technology. The pressure leach residues can be treated for the recovery of elemental sulphur, lead and silver. With the conversion of sulphur to the elemental form, zinc pressure leaching allows zinc winning to be independent of sulphuric acid production. Direct pressure leaching of zinc sulphide concentrates was started commercially in October 1980. Continuing research and development studies have defined various pressure leaching configurations for integration with existing roast-leach operations, for grass roots plants, or for plants which are to have the roast-leach section completely replaced. These studies have included the treatment of zinc concentrates from various Australian producers and the development of process flowsheets for potential applications in Australia.

Jan 1, 1989

By P. D. Georgescu

Gold, like no other metal, has a fascinating and special place in the world. It is used in a range of every day applications essential to modern life. Gold has long been considered the most precious metal in the world. Gold is used mainly for making jewellery as well as for dentistry, adornments on building and artistic expression. For thousands of years it has been used as an ornament of kings, a currency and standard for global currencies, and more recently, in a wide range of electronic devices and medical applications. Gold?s many unique properties have secured in a central role in history and human development. Today, more often than not, gold is extracted from ores. It occurs in vein and alluvial deposits and is often separated from rocks and other minerals by mining and processing operations. Some of these processes cause environmental concern (cyanidation, amalgamation, roasting). Besides primary gold ore resources, a series of secondary resources can be taken into account and processed for gold and silver recovery. There are two main types of waste produced. The first type is process waste, which includes tailing consisting of processing residues and waste rock. The other type is refuse from other different processes and recyclable materials. Among other secondary resources and/or by-products containing precious metals, which have been studied some processes and technologies with low ecological impact are presented in this paper. Heaps and tailing ponds resulted from gold-bearing ore exploitation and processing, refractory gold-bearing pyrite concentrates, slag resulted from electrolytic slime melting, gold-bearing chlorous slime are taken into account. In order to establish environmental friendly technologies for precious metals recovery from these secondary resources, laboratory experiments have been carried out on a pilot scale and in some cases on semi-industrial scale by applying specific technological processes, namely hydro-gravitational concentration, bio-oxidation, non-ionizing electromagnetic radiation (microwaves), solubilization without utilizing cyanide and gold recovery by ion-exchange resin. This paper presents the research results, technological principles as well as the possibilities of applying combined processes in order to treat different secondary gold-bearing resources.

Jan 1, 2006

By Edmund C. Pechin

THE iron trade of America seems on the point of a new departure. After years of struggling against heavy odds, patient endurance in periods of depression and loss, fears and hopes alternating as failure or success seemed to be the penalty or reward ; wanting in sufficient capital, embarrassed by reason of imperfect knowledge and lack of skilled labor, confronted by a powerful foe-every doubt has at last vanished, physical and mechanical difficulties have been largely overcome, capital has become more abundant and remunerative, the excellence of our product has been everywhere established, - and the peculiarities of American character-pluck, energy, and perseverance -have at last placed the trade upon a foundation so broad and stable that upon it we begin to erect the structure of a world-wide business. Concerning the future of the iron trade in the United States there can be but little doubt. The growing scarcity and constantly increasing cost of raw material in Great Britain, their loss of labor by emigration, the social disturbances among the working-classes, assuming a more threatening attitude on each new outbreak ; the rapidly decreasing value of money, in consequence of the enormous production of gold and silver, combine to forbid any return to former prices, and indicate that a point has been reached beyond which any marked increase of production is improbable. The same causes are operating to a greater or lesser extent upon the Continent. . In the meanwhile the growing wants of humanity are rapidly outstripping these sources of supply. In addition to the steadily increasing foreign and home demand, we find, the world over, the most intense activity everywhere displayed in enterprises requiring

By John Porter

(Cleveland Meeting, October, 1912.) Iv taking up this subject it is first necessary to define our terms. Efficiency, in its engineering usage, means the ratio between actual and theoretical results, and efficiency-records thus involve the use of scientifically determined standards with which all results are compared. Scientific management is the methods used in increasing efficiency, and includes the use of efficiency-records. Effeciency-records do not alone constitute scientific management, but they are necessary to it, and any so-called system of management which is not based upon standards and standardization is fundamentally wrong. An efficient management and efficiency-methods in management are not the same thing. There are some people who have an instinctive genius for management and accomplish results without exactly knowing how they do it. Such a manager may obtain a very high efficiency without the aid of scientifically determined standards. On the other hand, it sometimes happens that poor results will accompany the use of efficiency-records, clue to a weak or indifferent management, which fails to make use of the information acquired. Efficiency-records are only a tool, and like other tools are worthless unless used. The ordinary cost, sheet and production-statement do not go far enough. They tell what has been done, but give no information as to how well it has been done. It is true that the man who is familiar with the industry and the plant in question may draw inferences and form a general idea of good work or bad work, but it can only be a very general and hazy idea. Comparisons with previous records or records of other plants are unsatisfactory, since there is nothing to show the cause of the differences.

Jan 4, 1913

By R. C. Davis, R. F. Berry, G. W. White, B. T. O’Connell, L. A. Stacha

P,, and v, may now be solved for by trial and error between Eqs. 2 and 3, by assuming time approaching zero and equating PI, to P12. Observe that the pressure under the slug, P12 of Eq. 3, does not remain equal to the P1, at the valve in Eq. 2 as the slug proceeds up the hole. To plot the profile of pressure vs depth, it is necessary to express P12 in terms of P11. To do so, the extent to which the original submergence length S changes with respect to time must be analyzed. At the end of time t after injection, the actual value of L in Fig. 3 is The fall-back v,(t) is now distributed in the gas and exerts pressure on the bottom. This, in addition to the weight of the gas, amounts to the difference in pressures from point to point. With the average pressure profile calculable, a true numerical value for the average pressure in the tubing may be obtained. The value of v, must be obtained experimentally, and since v,, S and D are known, the basic Eq. 1 may be solved for the amount produced. Knowing P, and the actual volume of tubing occupied by gas (vat), it is possible to calculate the volume of gas at standard conditions which is present in the

By Arthur Foote

AT THE end of the year 1914, the main North Star incline shaft had reached the 6300-ft. level, and encountered a vein dipping Southwest, or, exactly opposite to the North Star. Subsequent development failed to find the North Star vein continuing beyond this intersection, so the 6300-ft. level proved to be the bottom level of the North. Star vein, and very little ore was found below the 5300-ft. level. The new vein was called No. 1 vein. Development work carried on for the next 10 years discovered a third vein, called No. 2, branching off about 1200-ft. to the east, with a North-south strike and a west dip. No. 1 vein had about 900 ft. of backs above the 6300-ft. level before reaching the boundary line of the property, and No. 2 vein died out about 800 ft. above. During these 10 years, the money spent on development was increased from $54,000 in 1914 to $184,000 in 1924; the ore reserves steadily diminished until it was evident that the mine must close down unless by some means a large tonnage of ore could be developed quickly.

Jan 1, 1930

By Sammy Bansah, Komla Dzigbodi-Adjimah

Abstract-Ghana, a major West African gold-producing country, took a crucial step in 1986 to allow private participation in mining ventures that had hitherto been state controlled and starved of funds. This decision has led to a three-fold rise in gold production with substantial local and foreign capital once again flowing into exploration and mining projects. Though the rise in gold export is due primarily to increased production from large mines such as Ashanti Goldfields Corporation, Billiton Bogosu Gold, Tebrebie Goldfields and Ghana Australia Gold that work primary lode gold deposits on quartz veins and Banket conglomerates, a fair amount of gold comes from placer gold mining from which two new mines have been developed at Kwabeng and Bonte during the current gold boom. Also, placer gold mining is important locally because the lower capital outlay required for its development enables many entrepreneurs to operate small concessions and provide employment for a large pool of unskilled labor. Placer gold exploration and development in Ghana is labor-intensive. Pitting is the most used method although few employ the mechanized ("Banka") drilling. The advantages and disadvantages of the two approaches in the local setting are discussed. The gravel is normally sluiced and the gold recovered by amalgamation. The drawbacks to successful placer gold exploration in Ghana have been attributed to lapses in execution of exploration programs (Dzigbodi- Adjimah and Arhin, 1993; Dzigbodi-Adjimah and Gawu, 1994). However, the failure to recognize and set time frameworks and financial limitations for the various stages of placer gold exploration have spelt the doom of some projects. It is critical that the characteristics of the placer gold deposit be determined by efficient and cost effective means. A planned exploration supported by adequate flow of funds saves costs and leads to success. This article discusses the current Ghanaian situation and presents proposals from case studies for planning and budgeting placer gold exploration programs for use in similar settings.

Jan 1, 1995

By Ricardo Badilla-Ohlbaum

Copper has been used by man for a very long time and unlike certain other metals, it is an essential element for life. Its toxicity arises both from a deficit and excess copper exposure/intake. The focus of the current discussions in countries of the European Union (EU) and in some USA States, is based on the concerns, independent of the scientific facts and the economic status of these claims, of the negative influence of copper and other metals on health and the environment. These discussions have influenced the new regulations of copper in drinking water, and the approach to regulate the appropriate levels of copper in surface water, soils and sediments. To illustrate the challenges ahead for copper, the evidence by which the current US Environmental Protection Agency (USEPA), the World Health Organization (WHO) and EU recommendation and regulations regarding copper in drinking water have been derived is presented and discussed. The gaps between the demands for new standards of health and the environment and the practical scientific tools to achieve these goals are presented, and the need to develop new regulating paradigms is also illustrated. The introduction of methodologies for the regulation of essential elements and acute inorganic substances in drinking water is discussed, as well as the status of the present approach contained in the International Program of Chemical Safety Environmental Health Criteria, (EHC) N° 170. The impact of the possible restrictions on the use of copper in the EU because of health and environmental concerns in terms of the world market for copper is discussed.

Jan 1, 1999

By F. V. Tideswell

COAL being essentially a complex conglomerate of plant remains that have undergone decay and interaction in varying degree, it is understandable that attack on the problem of its chemical constitution by normal chemical methods should have been attended by but slight success. The obvious method of fractionation by means of selective solvents has yielded a few results of some value. Thus it is known that from many, if not all, bituminous coals organic solvents extract small percentages of oxygenated compounds, which are generally assumed to have been derived from the original plant resins, though a more probable source would appear to be the glycerides and waxes of the plants. Organic solvents also extract small proportions of hydrocarbons, the origin of which is doubtful. Of more importance is the action of such pseudo solvents as pyridine, which, in addition to their specific solvent action, have the power of resolving and simplifying a portion of the coal substance in a manner analogous to that by which water can disperse a hydrogel. Early, work with pyridine indicated that coals are composed of two main classes of compounds: the one soluble in organic solvents, the other capable of being partly dispersed in pyridine. Recent work has shown that the dispersion is colloidal in character and that it may be accomplished by the use of solvents less active than pyridine, such as benzene or chloroform, provided that the temperature of extraction is raised or the coal has been suitably preheated. The action of reagents on coal has proved of little value in the past, but some insight into the constitution of coal has been given by regulated .destructive distillation. Thus, it has been shown that coals behave on distillation as though composed of two main classes of compounds: the one readily decomposable at moderate temperatures (yielding mainly the paraffins), the other undergoing a preliminary early decomposition (with evolution of oxides of carbon and water) and yielding a residue that at higher temperatures breaks down, yielding much hydrogen.

Jan 3, 1925

By J. M. Gaines

THE use of oxygen in electric furnaces is relatively old, and the practice has been employed by several steelmakers prior to the recent impetus given generally to the use of oxygen in steelmaking. This application has been described recently in several publications,1 and a number of patents relating to the application of oxygen in electric furnaces have been issued.2 An effort is made in this paper to assemble recent information relating to the use of oxygen in electric furnaces and to present this material from a practical viewpoint, to an extent consistent with the withholding of certain operating data which manufacturers consider to be confidential. The use of oxygen has been extended during the past months in a number of additional steel companies by incorporating oxygen practice into regular production and by much increased experimentation. Available records show that oxygen is used more or less regularly at present in 18 shops, of which six utilize the oxygen for production and the others for experimen¬tation. The number of furnaces per shop using oxygen varies from one to six. Many types of electric-furnace steel have been prepared with the assistance of pure oxygen, including low-carbon and medium-carbon killed steels, low-carbon rimming steel and low-carbon and medium-carbon stainless and alloy steels. Oxygen has been used in furnaces of all sizes up to 90 tons capacity for accelerating charge meltdown and for reduction of carbon.

Jan 1, 1947