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By A. Kale

A chlorination pilot plant having capacity to produce 5?10 kg/hr of titanium tetrachloride is in operation at the chlorination facility in Mintek. The bubbling fluid bed chlorination plant can be operated in batch and/or continuous process to study the chlorination kinetics of various feedstocks. The chlorination of titaniferrous ores to produce titanium tetrachloride (TiCl4) was carried out during the commissioning of the pilot plant and also as part of the titanium programme carried out at Mintek. TiCl4 is a basic raw material for producing commercial titanium dioxide pigment and titanium metal. This paper discusses the challenges faced during the commissioning and operation of the chlorination pilot plant. It also discusses the effect on the auxiliary facilities and instrumentation as a result of the harsh operating conditions of +1000°C and use of corrosive gases like chlorine and titanium tetrachloride. It discusses the effect of physico-chemical properties of the titanium tetrachloride and iron chlorides. The effect on the chlorinator refractory lining due to heating and cooling of the chlorinator is also discussed. Besides the special provisions made during the design of the chlorinator, this paper also discusses the operational experience and possible solutions to be implemented in future. Keywords Fluid bed chlorination, titanium ore chlorination, titanium tetrachloride (TiCl4) production using fluid bed technology.

Jan 1, 2011

By Haiping Sun, Samir Ganguly, Oleg Ostrovski, M. Yaser Lone

Wettability of graphite by synthetic SiO2-Al2O3-CaO-MnO slags with varied MnO content and by industrial slags was studied at 1350-1600 °C using sessile drop method under argon atmosphere. Initial contact angle was the lowest (110-115o) for the MnO-free slag. For slags with 10-40 wt% MnO, the initial contact angle was in the range 125-135o. The contact angle decreased with the contact time. The change in the contact angle with slag mass was found insignificant. The surface tension of slags obtained from the drop shape analyses was 500-800 mN/m and varied in a narrow range with temperature and MnO concentration. The reduction rate increased with increasing MnO content in the synthetic slag from 20 wt% to 40wt% and temperature. Increasing temperature also increased the rate of reduction. No correlation was observed between the reduction rate and MnO content in the synthetic slags in the range 0-20 wt% and in the industrial slags. The rate of SiO2 reduction from the molten slag was close to the rate of MnO reduction. The MnO-free slag had the largest contact area with graphite substrate. Keywords: reduction, wettability, graphite, slag, manganese, surface tension.

Jan 1, 2007

By Sachihiko Tokunaga, Hirofumi Taguchi, Kenji Maruyama, Hidenori Takahashi, Yoshiyuki Morikawa

"Abstract The present study proposed a new liquefaction countermeasure to improve sandy ground and conducted a trial execution. The new method is a floating-type and lattice-shaped cement treatment method, where cement-treated soil is not fixed to a non-liquefiable stratum. A fixed structure such as treated soil should be formed at the side of the floating-type treated soil to reduce its lateral displacement. In the study, one-dimensional dynamic response analyses were first conducted to confirm the mechanism of the new method. Then, a series of centrifuge model tests were performed to demonstrate the effect under a stress condition at the prototype scale. The analyses and model tests confirmed the effect of the liquefaction countermeasure. Finally, trial executions were carried out to confirm high-quality vertical execution.INTRODUCTIONLiquefaction induced by an earthquake generates sand boiling and ground settlement. Other problems have also been reported, including a decrease in bearing capacity and an increase in the horizontal earth pressure against retaining walls. To prevent these problems caused by liquefaction of the ground, various countermeasures have been proposed, such as cement deep mixing and high-pressure jet mixing methods. These methods have the big advantage of being applicable to ground that contains soil with a fine-grain fraction. Furthermore, the unnecessary displacement caused by the construction can be reduced. In Japan, a lattice-shaped cement-treatment method has frequently been used at many construction sites to prevent liquefaction, where cement-treated piles are intersected to form a lattice, as shown in Fig. 1. The lattice-shaped walls can reduce the shear stress generated by an earthquake, restricting the liquefaction at that location. However, the construction cost of the cement treatment is relatively high compared to other methods such as the sand compaction pile (SCP) method, and needs to be reduced. In particular, the cost of the high-pressure jet mixing method, which can be applied to the liquefiable ground under existing structures, is significantly high. Therefore, decreasing the total volume of the cement treatment is necessary to reduce the construction cost."

Jan 1, 2014

Remote methane detection State and federal regulations require frequent measurements to verify that safe methane levels are maintained in underground coal mines. Ventilation control is the primary means of maintaining safe methane levels. In the immediate face area, where the highest methane levels occur, methane measurements are required every 20 minutes during active mining. To perform these measurements, temporary roof supports must be erected. This allows a miner to reach the face. There a hand-held methanometer is used to make the measurements. This procedure is time consuming and potentially hazardous. To facilitate the measuring process and reduce the miner's exposure to roof falls, the US Bureau of Mines has developed a prototype optical device. It can measure methane remotely from distances up to 12 m (40 ft). The device uses two infrared signals, reflected from the coal face, rib, or roof. One signal is absorbed by the methane, the other is not. The ratio of the two signals determines the average methane concentration in the face area. The prototype detector has also been successfully tested at the Lake Lynn, PA Laboratory. Instantaneous responses were obtained for methane in the ventilation airflow and for methane layered near the roof. Conventional methanometers required from five to 25 seconds to respond to the methane in the ventilation airflow. They did not respond to methane in the roof layer. For more information about the Bureau of Mines' remote detection research, contact Richard W. Watson, US Bureau of Mines, Pittsburgh Research Center, Box 18070, Cochrans Mill Road, Pittsburgh, PA 15236 or call (412) 892-6630. Ignition suppression system The incidence has increased of fractional spark ignition at the mine face. One reason is the advent of mechanical mining. Another is the more difficult ventilation conditions associated with deeper and more extensive underground workings. To cope with the problem of frictional ignition, the Bureau of Mines initiated research to develop a system that would provide rapid detection of incipient methane-air ignition. Then, rapid dispersion of a quenching agent would ensure that the methane flame was extinguished while it was still relatively small. This concept was successfully demonstrated by suppressing explosions in the Bureau's Bruceton, PA experimental mine. But the bulkiness of the early storage-dispersal system proved impractical to retrofit onto face equipment. In a cooperative effort by the Bureau and the Mine Safety and Health Administration, a more compact system has been developed and is being tested. A continuous mining machine has been equipped with four 1.8-m-long (6-ft-long) and two

Jan 9, 1987

By Peter Zhang

The immediate roof at the test site consisted of laminated clay shale that is likely to be susceptible to weathering. With seasonal dry-wet cycles in the mine ventilation air, the roof in the intake air would deteriorate and lose integrity over time. In many instances, the weathering-prone roof would gradually scale off piece by piece between bolts and over the entry corners. In some long-term entries, roof weathering could develop up to 2-3 ft deep with columns of bolted roof hanging under the upper intact roof. If wire mesh is used, the roof bags down and reduces the entry height, and the weight of the bagged roof tends to pull the bolts out and poses a safety hazard. An effective measure is always sought to support this type of weak roof that is sensitive to moisture degradation. One solution is to seal the roof shortly after entry development to prevent moisture penetration so that roof integrity can be maintained for the long term. In this application, a polymer-based sealing material was tested in the Rockspring mine for weathering protection and reinforcement. The material is a one-component polymer powder for spray application onto the roof and rib. The sealant material is mixed with water in the spraying nozzle to apply to the roof and rib as a paste. The product sets within 5-10 minutes and forms a membrane as thin as about 1/8-in. The membrane will quickly develop tensile and bonding strength within minutes and completely cure within a few days. Through sealing, bonding and lateral reinforcement, the integrity of the weak roof can be maintained. The material has been tried in a long-term evaluation over several months in a set of main entries in the Rockspring mine owned and operated by Rockspring Development, Inc., affiliate of Foundation Coal. Preliminary evaluation has shown that the material is an effective and economical solution to ensuring the long-term stability of weathering-prone roof.

Jan 1, 2009

By Henry Rawdon

THE following note describing the behavior of copper under rather unusual conditions is offered here for its suggestiveness rather than as a complete study of the question. The examinations described were made because of a request for information concerning the embrittlement of copper when heated in a molten salt bath (sodium chloride) for the purpose of cleaning it, as well as for softening it. It is well known that metals may be rendered very brittle by electrolytic action, in aqueous solutions, in all probability by the action of nascent hydrogen, and it was suspected that perhaps the embrittlement of the copper by means of the molten salt was produced in a somewhat similar manner. It was found that the copper was in contact with iron (or steel) while immersed in the molten salt, through the occasional use of an iron stirring rod, iron forceps for handling the pieces, and an iron pot for containing the fused salt. In the electrochemical potential series iron and copper stand some distance apart, copper being electronegative to the iron. Assuming that the two metals bear a similar relation to each other, when immersed in a bath of molten salt, as they do in an aqueous solution, they would be expected to form a galvanic couple, the copper being the cathode. By this means the copper might be embrittled, as often happens in aqueous solutions, by the action of the liberated hydrogen. In this case, however, the embrittlement must be attributed to some other agent than hydrogen. To demonstrate how copper may be embrittled under these conditions, two small rods, one of copper and the other of mild steel, approximately 3/8 in. (9.5 mm.) in diameter, were immersed in a bath of sodium chloride that had been heated somewhat above its fusion point (melting point of sodium chloride is 819° C.) and an electromotive force of approximately 6 volts from a storage battery was impressed upon the system. The copper was made the cathode and the action was continued for

Jan 2, 1920

By James Terry Duce

In order to facilitate interpretation of the data in this chapter, we print the following excerpts from circulars to authors, compiled by Mr. Frank A. Herald when he was Vice Chairman for Production of the Petroleurn Division: Generally in Table 1 the unit for presentation of data is a field. For our purposes a field is defined as the whole of a surface area wherein productive, locations are continuous. Such unit commonly includes and surrounds nonproductive areas. Such unit commonly includes a great variety of geologic conditions-—several units of continuous productive reservoirs of distinctly different structure and of distinctly different stratigraphy. Therefore it is hoped that our authors will subdivide "field" so as to enable students to make analyses that may have scientific and/or commercial value. As to each space in the tabulation, it is either (1) not applicable, (2) the proper entry is not determinable, (3) the proper entry is determinable, but not determinable from data available to the author, (4) the proper entry is determinable by the author. In spaces not applicable, the author will please draw horizontal lines; in spaces where the proper entries are not determinable, the author will please insert 2; in spaces where the proper entries are determinable but not determinable from data available to the author, the author will please insert y; in spaces where the proper entries are deter-minable by the author he will, of course, make such entries. Generally, y implies a hope that in some future year a definite figure will be available. Inability to determine precisely the correct entry for a particular space should not lead the author to insert merely y. Contributions of great value may be made by the author in many cases where entries are not subject to precise determination. In such cases the author should use his good judgment and make the best entry possible under the circumstances. For many spaces, the correct entries represent the opinion of the author (for example, "Area Proved") and in such cases the entries need not be hedged to such extent as in cases where the quantities are definite yet can be ascertained only approximately by the author. In cases under definite headings but where figures are only approximate, the author may use 2. For example, if the total production of a field is known to be between 1,800,000 and 1,850,000, the author may report 1,8xx,xxx; or if the production is between 1,850,000 and 1,900,000, the author may report 1,9xx,xxx. Where a numeral is immediately to the left of x or y, such numeral represents the nearest known number in that position. As to quantity of gas produced from many fields the question will arise as to whether the figures should include merely the gas marketed or should include also estimates of gas used in operations and gas wasted. Although rough approximations may be involved, our figures should represent as nearly as possible the total quantity of gas removed from the reservoir.

Jan 1, 1936

By William H. Spice

The year 1942 in the South Central Texas area was marked by a sharp curtailment of exploratory drilling as compared with the past several years. In the 33 counties that compose this district, 17 of which are nonproducing counties, only 51 exploratory wells were drilled during the year 1942. This compares with 118 exploratory wells drilled during 1941, or a decrease of more than 50 per cent. At the end of the year 10 active exploratory wells were drilling in this area, as against 19 being drilled at the end of 1941. Of the exploratory wells drilled, two brought in oil wells and were new field discoveries and one was a gas well extending a recently discovered shallow gas area in the western part of the district. This compares with five new oil fields, one new . gas field and two extension wells drilled in 1941. Both new field discoveries were small and in areas outside of the general trend of the main producing horizon of the district in Edwards limestone: One new field, the Imogene, in Atascosa County, is a deep Edwards limestone prospect at 7500 ft., and the other new field, the Poth, in Wilson County, is a sSEa110w Wilcox (Eocene) prospect at 4000 ft. Subsequent drilling in each field to the end of I942 has proved disappointing. There were no new discoveries along the old Balcones fault-line trend, although 35 of the exploratory wells were drilled in counties along this trend. Approximately 38 wells were drilled in or adjacent to the proven fields of the district, of which 18 were oil wells, 2 were gas wells and 17 were dry holes. The district produced 6,186,178 bbl. of oil during 1942, which was a 7 per cent decrease under production for 1941. Approximately 4,961,000 bbl. of this total production, a slight increase over 1941, was produced by the four Edwards-limestone fields, Luling, Branyon, Salt Flat and Darst Creek, and the rest of the production came from the other 42 active fields in the district. During the year, 20 new producing wells were completed and 221 wells were abandoned in the producing fields. This alarming excess rate of abandonment~ over completions will be further reflected undoubtedly by a further decreased rate of 1943 production under 1942. Two active fields in the district in which more than one producing well was completed during the year were Bee Creek and Washburn. The majority of exploratory work in the district was confined to areas along the Wilcox trend, with a certain amount in progress along the deeper Edwards limestone trend. The successful completion of sevemi wells in the Washburn field from multiple sands in the Lower Wilcor (Eocene) has stimulated exploratory work along this trend, while the completion of a small well in the Imogene field from the Edwards limestone at 7500 ft. has renewed interest in this horizon at depths greater than generally are producing in the district. New Fields ounty. ble Oil and Refining Company's No. I

Jan 1, 1943

By James Terry Duce

In order to facilitate interpretation of the data in this chapter, we print the following excerpts from circulars to authors, compiled by Mr. Frank A. Herald when he was Vice Chairman for Production of the Petroleurn Division: Generally in Table 1 the unit for presentation of data is a field. For our purposes a field is defined as the whole of a surface area wherein productive, locations are continuous. Such unit commonly includes and surrounds nonproductive areas. Such unit commonly includes a great variety of geologic conditions-—several units of continuous productive reservoirs of distinctly different structure and of distinctly different stratigraphy. Therefore it is hoped that our authors will subdivide "field" so as to enable students to make analyses that may have scientific and/or commercial value. As to each space in the tabulation, it is either (1) not applicable, (2) the proper entry is not determinable, (3) the proper entry is determinable, but not determinable from data available to the author, (4) the proper entry is determinable by the author. In spaces not applicable, the author will please draw horizontal lines; in spaces where the proper entries are not determinable, the author will please insert 2; in spaces where the proper entries are determinable but not determinable from data available to the author, the author will please insert y; in spaces where the proper entries are deter-minable by the author he will, of course, make such entries. Generally, y implies a hope that in some future year a definite figure will be available. Inability to determine precisely the correct entry for a particular space should not lead the author to insert merely y. Contributions of great value may be made by the author in many cases where entries are not subject to precise determination. In such cases the author should use his good judgment and make the best entry possible under the circumstances. For many spaces, the correct entries represent the opinion of the author (for example, "Area Proved") and in such cases the entries need not be hedged to such extent as in cases where the quantities are definite yet can be ascertained only approximately by the author. In cases under definite headings but where figures are only approximate, the author may use 2. For example, if the total production of a field is known to be between 1,800,000 and 1,850,000, the author may report 1,8xx,xxx; or if the production is between 1,850,000 and 1,900,000, the author may report 1,9xx,xxx. Where a numeral is immediately to the left of x or y, such numeral represents the nearest known number in that position. As to quantity of gas produced from many fields the question will arise as to whether the figures should include merely the gas marketed or should include also estimates of gas used in operations and gas wasted. Although rough approximations may be involved, our figures should represent as nearly as possible the total quantity of gas removed from the reservoir.

Jan 1, 1936

By S. K. Mishra

Introduction The history of the Australian coal industry is almost as old as the history of Australia after new settlement. The first cargo of coal was exported from Newcastle to India in 1799. Coal has been mined in Australia for almost two centuries. But there are indications that the first coal was processed in 1877 in the Newcastle area. This is nearly 50 years after the first coal processing in Europe. Processing on any significant scale began in 1944 at the Newcastle Steel Works. In Queensland, however, coal processing did not begin until the second quarter of this century. The dramatic growth of mining and processing of Australian coal since the mid-60s is primarily due to the expansion of the export market in Japan, Asia, and Europe. Australian coals Black coal occurs in most of the major sedimentary basins of Australia. The better known deposits of commercial importance are in the Sydney, Bowen, Oakland, and Gailiee Basins. Apart from the Collie Basin in western Australia, other coal deposits of the Arckinga Basin in South Australia, the Bonaparte Basin in Northern Territory, and the Tasmania Basin are basically unexploited. The Sydney Basin of New South Wales and Bowen Basin of Queensland remain the major producers of black coal in Australia. Currently exploited or potentially commercial deposits of black coal in Australia occur in strata ranging in age from Permian to Tertiary. Estimated black coal reserves are summarized in Table 1. Coals from different ages have significant differences in their petrographic characteristics. Many of the Permian coals are usually rich in inertinite. Jurassic and Tertiary coals are typically rich in vitrinite content. Typical petrographic and chemical characteristics of some important Australian coking coals are summarized in Tables 2 and 3. The reserves of coking coals are restricted in the main to the Permian coals of the Sydney and Bowen Basins. Coal deposits in the latter are at shallow depth. A high percentage of these are being strip-mined. On the other hand, in the Sydney Basin, the majority of the reserves of good quality coking coals are at significant depth. The mining cost of these deposits is substantially higher than those in the Bowen Basin. It is usually possible to make strong coke with Australian Permian coals of vitrinite content much lower than the other international coals. But there are many major Permian deposits in Australia where low vitrinite content presents problems. As they are classified as marginal coking coals, optimization of their pro¬cessing plays an important role in meeting the market specifications of coking coal. The major reason for processing Australian coal is to reduce the ash content. Compared with British and some American coals, Australian coals are of relatively high ash content. Unlike American coals, more than 99% of the Australian coal deposits have sulfur content less than 1%. Consequently, sulfur control has never been a major problem. The coking quality of coal is improved simply through the ash reduction in the marketable product. However, with the increase in intensive mechanization and multi-stage handling of coal be-

Jan 9, 1985

By R. A. Marshall

Much has been written by men connected with the coal mining industry, and mining laws have been enacted for the safety of the men employed in the mines, and for the protection of property connected therewith. It seems almost impossible for anyone to select a subject that has not already been read, discussed and put into effect, especially in the coal mines of Western America. There is, however, a subject of much interest to the mining public, and to which I have given a great deal of study and consideration, and which I believe will be received by this convention, and will be given due consideration in the future in applying it to the safety of the mine,- "Efficiency in Shot Firing." Beginning with 1865, and for a period of 28 years in the state of Colorado, the annual reports of the chief inspectors show that 1159 coal miners were killed in the following manner: Five hundred eighty-two by falls of rock and coal ; 517 by gas and dust explosions; 6o by careless handling of explosives and the shooting of coal by the, individual, miner. It is my firm belief that 75 per cent of these fatal accidents might have been avoided, if a safe and proper shot firing system had been installed, at each and every mine. This may sound unreasonable, but I believe that the blasting of coal by the individual miner, and the use of black powder, squibs and fuse has, in reality, caused the death of many miners, from shock after blasting, the shooting out 'of timbers, and working in powder smoke, which fatal accidents were attributed to falls of rock or coal. These conditions led the people of Colorado, through their representatives of the General Assembly of Colorado, to enact a new coal mining law, and in 1913 this law became effective, containing twelve sections devoted to the subject of Efficiency in the System of Shot Firing. During the period 1913 to 1920, the employment of a shot firer, the use of permissible. powder, and the electric hand battery has resulted in safer mines, safer miners and safer shot firers, and I believe every coal mine in the state should employ first-class, certified shot firers, use permissible powder and fire the shots with an electric hand battery. I believe where gas generates in dangerous quantities, which is generally determined by inspection of the mine, and the daily report, the shooting in. such a mine should be done by electric battery located outside of the mine. Where permissible powder is used, I have seen the shot firer start down the mine with a belt around his waist containing one hundred caps, a safety lamp to test for gas, and an open light to ignite the fuse. Would it not be much safer for the shot firer if he used the electric hand battery? In non-gaseous mines where black powder is used, I have. seen the miners carry fuse into the mine, and shot firers have been known to partly tamp the holes, which was

Jan 1, 1921

By William H. Spice

The year 1942 in the South Central Texas area was marked by a sharp curtailment of exploratory drilling as compared with the past several years. In the 33 counties that compose this district, 17 of which are nonproducing counties, only 51 exploratory wells were drilled during the year 1942. This compares with 118 exploratory wells drilled during 1941, or a decrease of more than 50 per cent. At the end of the year 10 active exploratory wells were drilling in this area, as against 19 being drilled at the end of 1941. Of the exploratory wells drilled, two brought in oil wells and were new field discoveries and one was a gas well extending a recently discovered shallow gas area in the western part of the district. This compares with five new oil fields, one new . gas field and two extension wells drilled in 1941. Both new field discoveries were small and in areas outside of the general trend of the main producing horizon of the district in Edwards limestone: One new field, the Imogene, in Atascosa County, is a deep Edwards limestone prospect at 7500 ft., and the other new field, the Poth, in Wilson County, is a sSEa110w Wilcox (Eocene) prospect at 4000 ft. Subsequent drilling in each field to the end of I942 has proved disappointing. There were no new discoveries along the old Balcones fault-line trend, although 35 of the exploratory wells were drilled in counties along this trend. Approximately 38 wells were drilled in or adjacent to the proven fields of the district, of which 18 were oil wells, 2 were gas wells and 17 were dry holes. The district produced 6,186,178 bbl. of oil during 1942, which was a 7 per cent decrease under production for 1941. Approximately 4,961,000 bbl. of this total production, a slight increase over 1941, was produced by the four Edwards-limestone fields, Luling, Branyon, Salt Flat and Darst Creek, and the rest of the production came from the other 42 active fields in the district. During the year, 20 new producing wells were completed and 221 wells were abandoned in the producing fields. This alarming excess rate of abandonment~ over completions will be further reflected undoubtedly by a further decreased rate of 1943 production under 1942. Two active fields in the district in which more than one producing well was completed during the year were Bee Creek and Washburn. The majority of exploratory work in the district was confined to areas along the Wilcox trend, with a certain amount in progress along the deeper Edwards limestone trend. The successful completion of sevemi wells in the Washburn field from multiple sands in the Lower Wilcor (Eocene) has stimulated exploratory work along this trend, while the completion of a small well in the Imogene field from the Edwards limestone at 7500 ft. has renewed interest in this horizon at depths greater than generally are producing in the district. New Fields ounty. ble Oil and Refining Company's No. I

Jan 1, 1943

By J. Murray Riddell

The method of treating hazards wherein value is decreased, is cited by R. D. Parks. Quite properly, the theory of probabilities is made use of when multiple hazards are under consideration. E. F. Fitzhugh, Jr. $ deals with the enhancement phase graphically and uses percentage of expectancy as derived by a study of conditions and the selection of a chance factor. It is believed that both of the authors referred to fully recognize the part which human judgment plays, and as coupled with experience, training, and the application of the theory of probabilities; in that respect the composer of this paper is in accord. Within the past year, the task of arriving at a mathematical method for handling the enhancement phase, and, additionally, coupling the negative and positive phases, was explored. In citing the hazard, or negative phase, reference is made to the text by Parks. Types of Items far Consideration On the hazard, or negative, side some of the common items to be considered are: 1. Subsidence and resulting damage. 2. Flo wage of water above that anticipated. 3. Geological. (a) Decline in quality of probable ore, and/or (b) Decline in quantity of probable ore. 4. Depressed economic conditions. 5. Litigation. Similarly, on the enhancement, or positive, side common items to be considered are: 1. Flo wage of water below that estimated. 2. Geological. (a) Increase in quality of probable ore, and/or (b) Increase in quantity of probable ore. 3. Elevated economic conditions. 4. Litigation. 5. Technological advance in the art. Tn all of the above items no consideration is given to placing a value on, or giving consideration to, possibilities. For example, referring to Table 1, the estimated normal present value (Vp) of a property, exclusive of risk consideration, is taken as $100,000. If subsidence affects the usefulness of the shaft, the present value of the property will decrease to $60,000, and it is judged that there is a 1 in 4 chance that the shaft will be impaired;, consequent.ly, if subsidence took place, the present value would be reduced ($100,000-$60,000) $40,000, but since the chance is 1 in 4, the allowable reduction would be only one-fourth of $40,000, or $10,000, or a discount of 10 pct (hazard factor) of the original value; the related safety factor is taken as unity minus 0.10, or 0.90. Thus, the original Vp, $100,000, multiplied by the safety factor ($100,000 X 0.90) gives $90,000, which is the adjusted present value of the property in this single instance. Additionally, there is a water hazard, which, if encountered, will reduce the present value to $85,000. The chance is 1 in 3. Following through with the same reasoning as shown above, the derived safety factor will be 0.95. To arrive at a single multiplying factor which will express the combined risks, the two safety factors are multiplied together, 0.90 X 0.95 = 0.855. That factor when multiplied by the origirial Vp will give the adjusted, and

Jan 1, 1950

By Peter F. Weiss

INTRODUCTION Austro-American Magnesite Co. of Radenthein, Carinthia, Austria, is a wholly owned subsidiary of General Refractories Company, Bala Cynwyd, USA, and has been incorporated since 1908. The raw material basis is the magnesite mine on Millstatt Alp, located in the mountains near Radenthein at an altitude of 1500 m above sea level. The mined crude magnesite is crushed in a surface crushing plant to minus 35 mm and consequently hauled to the processing plant in the valley by means of a cable conveyor of 7.5 km length. The annual production of 350,000 mt is accomplished with 20 supervisors and 122 workers (of those 60 are in the mine). The labor requirement for block caving is 0.2 man hr/mt, corresponding to an output of 40 mt/man/ shift. GEOLOGY The rock in this area mainly consists of crystalline type schist. There are mostly coarse crystalline garnet mica schists with varying mineral concentrations, and to a lesser degree, some deposits of amphibolite and marble. This petrographically rather homogeneous rock is divided into numerous different tectonic units (covers and scales). The magnesite deposit itself is a foreign body that also has been tectonically inserted. The ore body has a length of 600 m, is 450 m deep, and has a thickness of 60 m on average, varying substantially however, The contact with the accessory rock is very precise. The deposit 1 = ore body, 2 = previous open pit, 3 = caved in area, 4 = block under excavation, 5 = land slide consists of coarse crystalline magnesite in excess of 90 per cent. The few impurities consist of dolomite and talc. The lower part of the deposit is inclined parallel with the schists at approx. 40 degrees. In profile it can be seen, however, that the upper part of the deposit has been tilted over. This is a result of a post-glacial land slide reaching from the bottom of the valley at 1400 m above sea level to the peak of the mountain at 2100 m above sea level. Due to this land slide, with horizontal movements of up to 100 meters, as well as older tectonic events, the rock was crushed to a vast extent. Through mining, the land slide was reactivated; about 40 million cubic meters of rock slowly flow downhill almost like a plasticized mass. Near the surface, the rock is completely crushed and resembles a glacier rupture zone. This renders the originally impermeable rock completely water permeable so that practically all of the annual quantity of 1000 to 1100 mm of precipitation permeates the rock and flows down into the mine. The carbonate rock turns into the preferred aquifer. From 1700 to 2600 cubic meters of water have to be pumped from the mine daily. On one hand, additional problems are caused by the water in the mine, on the other hand we have learned to make use of the down- hill pressure forces to improve the crushing process during block caving. The boundary of the downhill shearing zone moves downward as mining goes deeper.

Jan 1, 1981

By D. W. Fuerstenau

MEASUREMENT of zeta potentials is a useful tool to study the surface chemistry of minerals under flotation conditions.1,2 Because there is continued interest in this approach, the apparatus for obtaining zeta potentials of nonconducting solids by the streaming potential method is outlined here. Fig. 1 illustrates the streaming potential apparatus." The streaming potential cell or plug consists of two 24/40 standard ground joints (4) joined with a piece of pyrex tubing 60 mm long and 12 mm in diam (5). The electrodes are made of bright platinum disks 19 mm in diam and 1 mm thick through which 0.5-mm holes have been drilled (6). To the surface of each is welded a piece of 80-mesh platinum gauze. Each electrode is permanently mounted on the ends of the inner parts of the two standard joints by means of a platinum wire (7) which connects it to the tungsten seal at the end of the cell (8). For ease in cleaning and handling the apparatus, the streaming cell is fastened to the 500-ml reservoir flasks (1) by means of two 18/9 ball and socket joints (2). This particular arrangement permits passage of the solution in either direction through the plug of particles. Flow of solution can be stopped by a stopcock (3). One of the reservoir flasks has a large opening to permit insertion of either a thermometer or a pair of electrodes for measuring pH of solutions within the system. In making the experiments, the plug is filled with 48 to 65-mesh particles, but a layer of 28 to 35-mesh particles is placed at each electrode to prevent any of the finer particles from passing through holes in the electrodes. The assembled apparatus is shown schematically in Fig. 2. To eliminate CO2 from the solutions, all experiments are conducted in a nitrogen atmosphere. Nitrogen, used to drive solutions through the plug, is passed through a bottle of concentrated KOH solution to remove CO2 (9). A 9-liter ballast reservoir (10) is used to maintain a more nearly uniform pressure. A series of stopcocks controls the direction of flow nitrogen to the flasks (11). Tubes of as-carite prevent backflow of CO2 into the system (12). Driving pressure, which can be set at any desired value, is measured with either a water manometer (13) or a mercury manometer (14). Reservoir flasks have side arms for making pressure corrections for the difference in water levels in the flasks. Streaming potentials are measured by the circuit illustrated in Fig. 2. The electrodes from the plug are connected through mercury wells (15) to a reversing switch (16), which reverses the polarity of the electrodes depending on the direction of flow of solution through the plug. The streaming potential is measured with a Leeds and Northrup type K2 potentiometer (17). Proper choice of null instrument is important because Eq. 1 assumes that the current which escapes through the measuring instruments is negligible. An ordinary galvanometer cannot be used to determine the null point because

Jan 1, 1957

By Arch J. Alexander

COAL is produced, in commercial quantities, in thirty-five of the sty-five counties of West Virginia. Oil and gas are produced, commercially, in forty-two counties. So, you may readily see that coal, oil and gas are closely related as to production areas. Many of the West Virginia coal mines are studded with oil and gas wells, as drilling has been done in thirty-two of the coal bearing counties. When the drilling of oil and gas wells was placed under the regulatory control of the Department of Mines on June I, 1929, it was estimated, by the State Geological Survey, that 64,000 wells had been drilled in West Virginia and that 34,mo wells were then being operated as oil and gas producers. No records of many of these remaining 30,000 abandoned wells exist and some of them remain a standing menace to safety as our coal extraction continues. Of a total of 13,100 new wells drilled since June 1929, approximately 5,200 have been drilled through coal measures. Approximately 7,000 wells, which were drilled through coal measures, have been abandoned in the same period of time. Many of these wells were drilled prior to the enactment of the oil and gas laws. Prior to the enactment of the Oil and Gas Law, which established the Oil and Gas Division of the Department of Mines in 1929, there had been several mine explosions attributable to cutting into un- charted wells and the improper plugging of other wells. The most serious explosion was that of Mines No. 47 and No. 49 of the Consolidation Coal Co. in Marion Co., when one of the so-called plugged wells leaked or seeped through some 80 ft of strata to the coal bed elevation, filling the mine with gas, the gas being ignited, killing a good many men and wrecking two coal mines. Legislation, to combat well hazards to coal mines, was slow in coming. In 1928, R. M. Lambie, then Chief of the Dept. of Mines, got sufficient support from coal, oil and gas interests to get the legislature to pass our present oil and gas laws. These statutes not only protected the coal industry but went a long way toward conserving the oil and gas resources of our state. Before drilling for oil or gas on any tract of land, known to be underlaid with one or more workable seams of coal, the well operator is required to submit a map of the area showing the location of the proposed well, and to send a copy to the Dept. of Mines and a copy to the coal operator. If no objections to the location of the proposed well are made by the coal operator within ten days, a drilling permit and a number for the well are then issued and work may proceed. If, however, the location of the proposed well is objected to by the coal operator, on the grounds that the location of the well will interfere with present mine operations, projected workings, or other- wise Cause a dangerous condition, the operator may file a written objection with the Dept. of Mines.

Jan 1, 1948

By J. P. Heller, H. B. Bradley, A. S. Odeh

It is an accepted procedure to represent oil field displacement problems in which the pressure is relatively constant by a potentiometric model. Variations in reservoir permeability thickness product are represented in the model by proportional variations in electrolyte depth. It is shown that significant errors are present wherever these variations are of such magnitude that the consequent differences in the electrolyte depth in the model or any regions therein are appreciable in comparison with their respective horizontal dimensions. To demonstrate the order of magnitude of this error, a hypothetical linear oil field in which permeability varies linearly with distance was treated both analytic.ally and by potentiometric model. The results obtained from the model are compared with the exact solution for various configurations of linear geometry. Deviations in flow times up to 11 per cent were observed. It is confirmed that these discrepancies can be reduced by increasing the areal scale and/or decreasing the vertical scale of the model. It is the purpose of this work to assist in the design of potentiometric models by indicating the relationship between this error and the chosen scale factors. INTRODUCTION The fundamental geometrical criterion which determines whether the pressure distribution in an oil or gas reservoir may be simulated in a conventional potentiometric model is the requirement that all reservoir parameters be constant along any vertical line between its upper and lower boundaries. This situation never obtains exactly; nevertheless, it is usually assumed that there is no permeability stratification within the section of interest, that all wells completely penetrate the sand, that there are no gravitational effects, and that variations in thickness of the sand are small compared to the horizontal extent of the field. In these ways the reservoir problem is reduced to two dimensions in which there is no variation of pressure in the vertical direction within the limits of the sand. Variations in sand thickness and/or horizontal pesmeability may be taken into account as described by Muskat, by considering the fluid conductivity of the reservoir in its horizontal plane to be proportional to the product of permeability and sand thickness. If the variations in sand thickness are small compared to the horizontal dimensions of the reservoir, then it is a good approximation to consider the reservoir problem to be essentially two dimensional. The same approximation, however, is made in the simulation of the assumed two-dimensional reservoir by the electrolytic model. The model, if it is to take into account variations of permeability-thickness product, must of necessity be made in three dimensions, that is, with variable depth. Most potentiometric model studies and theoretical treatments reported in the literature to date2,3,4,5,6,7,8 are those in which either an average permeability was used or a constant permeability was assumed. This is understandable since detailed permeability data are not usually available for the majority of reservoirs. Many investigators have recognized that the failure to incorporate permeability variations within a reservoir in model studies leads to serious error in predictions made

Jan 1, 1957

By D. C. Porterfield

ProUuction of crude oil in Venezuela increased from 186,134,000 bbl. in 1940 to 2~8,131,ooo bbl. in 1941, or 22.6 per cent, to establish a new all-time high for the country. While the average production for the year was 625,000 bbl. per day, production during the month of December 1941 averaged 751,000 bbl. per day, and during the last week of the year, 766,000 bbl. per day. Production from the Lake Maracaibo basin averaged 454,000 bbl. per day during the year, or 72 per cent of the total for the country, compared with 73 per cent of the total produced in 1940. Drilling during the year was approximately on the same scale as in 1940, with 438 wells completed in 1941 as compared with 429 the year before. Exploratory completions decreased from 18 in 1940 to 6 in 1941. Of the drilling operations in 1941, 56 per cent was concentrated in the Lake Maracaibo basin and 44 per cent in eastern Venezuela, success being 98 per cent in the Lake basin and 83 per cent in the east. Successful completions for the country as a whole amounted to 92 per cent of the total wells drilled. Exploratory drilling in 1941 resulted in the discovery of three new fields, all in eastern Venezuela; viz., Guara, about II km. to the northeast of the Oficina field but on a separate structure; Santa Rosa, which is east of El Roble field on a structure forming a part of the major Santa -Ana- San Joaquin-El Roble uplift; and Santa Barbara, which is southwest of the Jusepin field on an extension of the main Jusepin anticline. At the close of the year three wildcats were drilling, all of which showed prospects of obtaining production; that is, Mercedes No, 2 in central Guarico, Las Ollas No. I on the Anzoategui-Guarico border near the town of Zaraza, and Quiamare No. I in Anzoategui northeast of the town of San Mateo. In spite of heavy withdrawals and the resultant natural decline in the potentials of older producing areas, new drilling during the year increased the potential production of the country from an estimated 780,000 bbl. per day at the end of 1940 to an estimated 810,000 bbl. per day at the end of 1941, or approximately 4 per cent. Since domestic consumption of petroleum products is insignificant compared with total production, exports of crude and products during the year increased in line with production. Crude exports totaled 196,800,000 bbl., compared with 158,400,-000 bbl. in 1940, and exports of products were 26,100,000 bbl., compared with 21,900,000 bbl. the year before. Exports of crude from Venezuela to the United States amounted to 36,500,000 bbl. In addition, about 2,200,000 bbl. was imported in bond into the United States for transfer to Canada. Total refining capacity of the country in 1941 was approximately 125,000 bbl. per day, including a crude-conversion plant with a capacity of 32,000 bbl. per day, capable of making fuel oil only. Three plants with a capacity of 121,000 bbl. Per

Jan 1, 1945

By M. R. Geer, H. F. Yancey

Coal washing assumed an important role in the mining industry of the Pacific Northwest long before washing practice became firmly established in the Appalachian field. A Scaife washer was operated in the state of Washington in 1887; and by 1927, the fist year for which complete statistics were compiled, nearly a third of the state's coal production was washed, in comparison with only about 5 pct for the country as a whole. Mechanical preparation was adopted in Alaska in 1922 in a plant constructed by the United States Navy at Chickaloon to provide bunker coal for naval forces operating in northern waters. Many of the coal beds mined in Washington and Alaska contained more impurities than those mined elsewhere, and this circumstance contributed to the early interest in mechanical cleaning. A much more important factor, however, was the inclination of the coal beds. With steeply pitching beds, hand sorting by the miner at the face is impossible; consequently, all material must be loaded and dealt with on the surface, just as is now proving the case with mechanical mining of flat beds. Thus "full-seam" mining afforded the same stimulus to the early development of coal washing in the Northwest that it is providing under mechanization in the rest of the country today. Objeet and Scope ' This report is intended to provide a general summary of the status of coal-washing practice in Washington, Oregon, and Alaska—an area in which some of the coals mined are more difficult to wash than those mined elsewhere in the country. Detailed flowsheets of plants, statistical data on production, and cost figures have been omitted, largely for the sake of brevity but also because such information is principally of only local interest. On the other hand, considerable washability data have been included because they are Washington At present Washington leads all other states in the percentage of its total production that is cleaned mechanically, 82.1 pct in comparison with the national average of 25.6 pct in 1945.' The washing problems encountered in this state are highly variable because the mountain-building forces that created the Cascade Range caused such intense folding and faulting of the beds in some fields that the rank of the coal was increased to anthracitic, while in other fields more distant from the mountains the beds were relatively undisturbed, and the rank of the coal ranges down through subbituminous to lignitic. The complicated and burdensome schedule of sizes prepared in most coal fields has never been required by the Washington market. With but few exceptions, lump is prepared on a round-hole screen of about 3 in. size, egg is about 3 to 1 5/8 or 1½ in., and nut is 1 5/8 or 1½ in. to either 1 or ¾ in. Some mines screen no finer than ¾ in. and market a slack coal of that top size, but generally the coal is screened at about ¼ in. to give a stoker coal of ¾ or 1 to ¼ in., and a ¼ in. to 0 "buckwheat." During recent years the market for lump coal has largely disappeared, and lump is crushed to supplement the pro-

Jan 1, 1950

By T. D. Tiemann

The caustic extraction of silica from Wisconsin and Minnesota taconite was investigated by bomb digestion over the temperature range from 312 to 40S°F at caustic concentrations from 25 to 500 gpl. Residual concentrates containing as much as 65 pct iron were obtained. The high rate of silica extraction is related to a microcrystalline variety of quartz, since it is shown that the rate of extraction of silica from quartz is directly proportional to its surface area. Increasing dependence on foreign ore reserves makes the need for developing the technology necessary for treatment of our low grade ores even greater than it was at the time of World War 11, when much research was conducted on the extraction of alumina from clays. Representative of these were the studies carried on at the University of Illinois.' More recently, the U. S. Bureau of Mines investigated the production of alumina from anorthosite, and currently the aluminum industry is showing renewed research interest in this field. The studies reported here are part of a continuing research program based on the above concepts and aimed at the eventual development of processes for the treatment of low grade ores, particularly those of iron. The fact that large reserves 3 of low grade nonmagnetic taconite are contained in the iron formation of the Wisconsin Gogebic range have made this ore an important and attractive target for investigation. The idea of removing silica by caustic extraction is not new.495 The digestion in caustic solution of ground flint, diatomite, and other forms of chalcedonic silica is the basis for the production of soluble sodium silicates by the wet-process. Upgrading bauxites by the caustic extraction of silica has been investigated6 and is the subject of a German patent.7 Although mention is made by Roe' of the caustic extraction of silica from low grade Michigan and Wisconsin iron ores, and he lists a number of patents and references on the subject, recent work in the field does not appear to be extensive. As far as the author knows, there has been no work in this field on these particular ores. It is hoped that this paper will stimulate further investigation which will eventually lead to an econclmic means of processing these large low grade reserbes. TACONITES The taconites investigated in this study were from Minnesota and Wisconsin. That from Minnesota, a semi-taconite, Nas obtained from the Oliver Iron Mining Division, U. S. Steel Corporation, and represents a sample of an oxidized iron formation from their King Mine on the Mesabi range. The Wisconsin taconite came originally from the trench sampling of the U. S. Bureau of Mines, and represents a composite of the Norrie, Pabst, Yale, Plymouth, and Pence members of the Gogebic iron formation. Assays on these samples are given in Table I. A typical calcu1atr:d average analysis of the Wisconsin taconite is given in Table 11. Chemically, the Minnesota semi-taconite sample contains about 39 pct iron and 39 pct silica, while the Wisconsin taconite contains 30 pct iron and 53 pct silica, both on the dry basis.

Jan 1, 1962