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By F. F. Peng, A. D. Walters, M. R. Geer, J. W. Leonard

INTRODUCTION Washability characteristics derived from float-and-sink analysis in Chapter 4 demonstrate that coal is intrinsically heterogeneous, and this heterogeneity is also evident in the proximate, ultimate, and size analyses. A range of particles from high to low specific gravity is usually seen in the run-of-mine coal. One objective of coal preparation is to recover the high quality float material (the particles of lower specific gravity) such that the recovered product meets certain quality specifications, as well as to reject or recycle low quality particles of higher specific gravity. The maximum recovery of cleaned coal at the required quality is of major concern to plant operators. However, the quantity and quality of products of coal cleaning, determined in the operation of actual commercial cleaning plants and by theoretical calculation based on run-of-mine washability studies, are known to be different with each coal. Therefore, during the last half century, coal preparation engineers have repeatedly sought methods to predict the technical and economical efficiency of separation of cleaning equipment and systems. Many formulas have been proposed by international investigators to evaluate the efficiency of various coal cleaning operations, primarily based on the yield and/or ash of the various products of coal cleaning. Performance criteria in use today are capable of defining all of the important aspects of a given concentrating operation; however each criterion has certain restrictions or limitations. It is important, therefore, to understand how such formulas can be used and the problems involved in their construction. Technical Measure of Plant Performance Conventional means for evaluating a preparation plant's performance are generally approached through the use of equipment performance mea-

Jan 1, 1979

By L. L. McMurray

ILMENITE is the most important raw material for manufacture of titanium dioxide.1 Industrially, several other products are made from ilmenite, the most important of which are: ferrotitanium, ferro carbon-titanium, copper-titanium, titanium carbide and titanium nitride. The production of titanium metal is still in the laboratory stage because of the difficulty of extraction and as yet no important application for the metal has been found. Ilmenite has received considerable attention as an industrial raw material. Imports of ilmenite concentrates for the first nine months of 1941 were 156,737 short tons, the chief source being Travancore, India.2 Domestic production of ilmenite has here-tofore been confined to Amherst and Nelson Counties, Virginia, where a complex rutile, ilmenite, and apatite ore is mined and treated to utilize all three of these minerals. A recent report3 has described development of the large titaniferous magnetite ore body at Tahawas, New York, where it is expected that 800 tons of ilmenite concentrates, containing 48 per cent Ti02 will be produced daily. Additional domestic production is expected from a large ilmenite deposit recently opened in Caldwell County, North Carolina. Flotation tests indicate that a high-grade concentrate containing 53 per cent Ti02 can be made from the North Carolina ore. Prospecting of domestic ores in other areas has been reported.4 It appears that increased domestic production of ilmenite may well save considerable shipping space so vitally needed in these times. The composition and chemical structure of pure ilmenite is given by Dana as: FeO, TiO2; Ti, 31.6 per cent, Fe, 36.8 per cent, 02, 31.6 per cent. This composition is variable in that some iron or titanium may be replaced, giving a variable iron-titanium ratio. As an example, the iron-titanium weight ratio of ilmenite in Caldwell County, North Carolina, has been determined to be 0.94 (using 97.1 per cent ilmenite concentrate obtained by heavy liquids on minus 150-mesh ore) compared with theoretical 1.16. No rutile was noted in this ore to account for the low value. This North Carolina ore is free of magnetite, which is a common associate of ilmenite ores. In view of a large potential production from North Carolina, the Tennessee Valley Authority conducted a study of methods of concentration of that ore, of which the results are reported herein. THE ORE Five samples of ore were taken from the deposit at various exposed locations and were mixed for the study and testing. An attempt was made to proportion the amount of weathered and unweathered portions in making the composite sample, so as to approximate actual operating conditions. An examination of representative specimens of the sample showed the following general facts: I. The black mineral comprising nearly 70 per cent of the ore is ilmenite.

Jan 1, 1944

By L. L. McMurray

Ilmenite is the most important raw material for manufacture of titanium dioxide.' Industrially, several other products are made from ilmenite, the most important of which are: ferro titanium, ferro carbon-titanium, copper-titanium, titanium carbide and titanium nitride. The production of titanium metal is still in the laboratory stage because of the difficulty of extraction and as yet no important application for the metal has been found. Ilmenite has received considerable attention as an industrial raw material. Imports of ilmenite concentrates for the first nine months of 1941 were 156,737 short tons, the chief source being Travancore, India.2 Domestic produttion of ilmenite has heretofore been confined to Amherst and Nelson Counties, Virginia, where a complex rutile, ilmenite, and apatite ore is mined and treated to utilize all three of these minerals. A recent report3 has described development of the large titaniferous magnetite ore body at Tahawas, New York, where it is expected that 800 tons of ilmenite concentrates, containing 48 per cent TiO2 will be produced daily. Additional domestic production is expected from a large ilmenite deposit recently opened in caldwell county, North carolina. Flotation tests indicate that a high-grade concentrate containing 53 per cent TiO2 can be made from the North Carolina ore. Prospecting of domestic ores in other areas has been reported.' It appears that increased domestic production of ilmenite may well save considerable shipping space so vitally needed in these times. The composition and chemical structure of pure ilmenite is given by Dana as: FeO, TiO2; Ti, 31.6 per cent, Fe, 36.8 per cent, O2, 31.6 per cent. This composition is variable in that some iron or titanium may be replaced, giving a variable iron-titanium ratio. As an example, the iron-titanium weight ratio of ilmenite in Caldwell County, North Carolina, has been determined to be 0.94 (using 97.1 per cent ilmenite concentrate obtained by heavy liquids on minus Iso-mesh ore) compared with theoretical 1.16. No rutile was noted in this ore to account for the low value. This North Carolina ore is free of magnetite, which is a common associate of ilmenite ores. In view of a large potential production from North Carolina, the Tennessee Valley Authority conducted a study of methods of concentration of that ore, of which the results are reported herein. The Ore Five samples of Ore were taken from the deposit at various exposed locations and were mixed for the study and testing. An attempt was made to proportion the amount of weathered and unweathered portions in making the composite sample, so as to approximate actual operating conditions. An examination of representative specimens of the sample showed the following general facts: 1. The black mineral comprising nearly 70 per cent of the ore is ilmenite.

Jan 1, 1948

By L. L. McMurray

Ilmenite is the most important raw material for manufacture of titanium dioxide.' Industrially, several other products are made from ilmenite, the most important of which are: ferro titanium, ferro carbon-titanium, copper-titanium, titanium carbide and titanium nitride. The production of titanium metal is still in the laboratory stage because of the difficulty of extraction and as yet no important application for the metal has been found. Ilmenite has received considerable attention as an industrial raw material. Imports of ilmenite concentrates for the first nine months of 1941 were 156,737 short tons, the chief source being Travancore, India.2 Domestic produttion of ilmenite has heretofore been confined to Amherst and Nelson Counties, Virginia, where a complex rutile, ilmenite, and apatite ore is mined and treated to utilize all three of these minerals. A recent report3 has described development of the large titaniferous magnetite ore body at Tahawas, New York, where it is expected that 800 tons of ilmenite concentrates, containing 48 per cent TiO2 will be produced daily. Additional domestic production is expected from a large ilmenite deposit recently opened in caldwell county, North carolina. Flotation tests indicate that a high-grade concentrate containing 53 per cent TiO2 can be made from the North Carolina ore. Prospecting of domestic ores in other areas has been reported.' It appears that increased domestic production of ilmenite may well save considerable shipping space so vitally needed in these times. The composition and chemical structure of pure ilmenite is given by Dana as: FeO, TiO2; Ti, 31.6 per cent, Fe, 36.8 per cent, O2, 31.6 per cent. This composition is variable in that some iron or titanium may be replaced, giving a variable iron-titanium ratio. As an example, the iron-titanium weight ratio of ilmenite in Caldwell County, North Carolina, has been determined to be 0.94 (using 97.1 per cent ilmenite concentrate obtained by heavy liquids on minus Iso-mesh ore) compared with theoretical 1.16. No rutile was noted in this ore to account for the low value. This North Carolina ore is free of magnetite, which is a common associate of ilmenite ores. In view of a large potential production from North Carolina, the Tennessee Valley Authority conducted a study of methods of concentration of that ore, of which the results are reported herein. The Ore Five samples of Ore were taken from the deposit at various exposed locations and were mixed for the study and testing. An attempt was made to proportion the amount of weathered and unweathered portions in making the composite sample, so as to approximate actual operating conditions. An examination of representative specimens of the sample showed the following general facts: 1. The black mineral comprising nearly 70 per cent of the ore is ilmenite.

Jan 1, 1948

By Dr. O’Neil Thomas J., Donald W. Gentry

"There are two characters to the value of mining properties-one mine may have a value, owing to its real intrinsic worth; an- other (having no intrinsic value) may have a value by being so situated as to harass the working of the really valuable mine-in mining camps one is looked upon as much of ligitimate enterprise as the other.'' -Victor Clement to Simeon Reed, Wardner, Jan. 11, 1890, Reed Mss. APPROACHES TO VALUATION Value and costs are two terms basic to financial analysis which cause, perhaps, the greatest amount of misunderstanding in mine valuation studies. When discussing the value of an asset or the costs of producing a product, it is absolutely essential that the speaker define the terms being used. There are many types of value and many categories of costs. Without specific accompanying definitions, value and cost data are not very meaningful. Value refers to a measure of the desirability of ownership of property. Some of the types of value which might be encountered in a mine valuation study are: 1) Market value 2) Full cash value 3) Salvage value 4) Replacement value 5) Capitalized value 6) Book value 7) Assessed value 8) Insured value Each of these has a specific meaning which can be applied to determine a monetary amount in a specific situation. The major item of interest here is the broader question of "what is the value of the mine?" or "what is the mine worth?" In this case, we are speaking of market value. Market value is the value (price) established in a public market by ex- changes between a willing buyer and a willing seller when neither is under duress to complete the transaction. Market value fluctuates with the degree of willingness of the buyer and seller and with the conditions of the sale. The use of the term market suggests the idea of barter. When numerous sales occur on a market, the

Jan 1, 1984

By Reinhard H. Wöhlbier, George E. Aiken

8.4-1. Introduction. Surface excavating is done on a continuous basis with a variety of machines: 1) trenchers and ditchers, 2) conveyor loaders, and 3) bucket-chain and bucket-wheel excavators (BWE). Surface mining is largely concerned with only the last two machines, although some of the conveyor-loader types are often used by contractors for large-scale earth moving, and the engineer should be aware of these applications. This chapter is restricted to discussing only the bucket-chain and bucket-wheel excavators, with special emphasis on the latter. Continuous digging with these machines is done with evenly spaced buckets on either an endless chain or on the periphery of a rotating wheel. The bucket-chain digger excavates and takes the material away from the face with the same machinery. In the case of the bucket-wheel machine, these two functions are separate. Material is excavated by the buckets and then flows in a continuous stream via a transfer to the conveyor system, which in turn transports it to the discharge point. The wheels are adjustable in rpm and mount 6 to 12 buckets of equal size. These are classed as celled, cell-less or semicelled. The digging ladders for both types can move simultaneously in the horizontal and vertical planes. Ladder control is similar to the operation of a bucket-line dredge. Some ladder-chain and all wheel excavators have the machinery deck and superstructure mounted on a 360° swing circle. Other chain diggers have a fixed machinery deck. Deep and/or high cutting models are available in either the chain or wheel excavator. Machines can be either rail or crawler mounted, but the trend is to crawlers. Many of the early ladder-chain, rail-mounted excavators have been converted to crawlers. These may be either of the single or bogie type, depending on the conditions. Large machines usually use the superior three-point crawler suspension.

Jan 1, 1968

By H. F. Mills

The Iron King mine is I2 miles east of Prescott Arizona, in low foothills of the Agua Fria mining district. It was operated in 1906 and 1907, using gravity methods of concentration, mostly on oxide ores. In 1923 and 1924 shipments of sulphide ores were made to the Humboldt smelter. It remained inactive and stripped unti1 1936, when it was unwatered and sampled to the 400-ft level, the bottom at that time. In 1937 the Iron King Mining Co. purchased the mine and shipped oxide ores. During 1938 a bulk flotation plant of I40 tons daily capacity was erected. The mill has been enlarged and operations have been continuous since the mill first started. In July 1942, the Shattuck Denn Mining Corporation purchased the physical assets from the Iron King Mining Co., and since that time it has operated as the Iron King Branch of the Shattuck Dcnn Mining Corporation. Economic metals recovered are gold, zinc, silver, lead, a little copper, and fluxing pyrite. The ore occurs as a series of northward-dipping shoots arranged in echelon pattern, the series extending over a length of 3500 ft. Strike lengths of shoots vary from 60 to 600 ft, and widths from 3 ft to as much as 14 ft. The ore occurs in a sheared zone in pre-Cambrian chloritic schist. This schist belt is about 6 miles wide, and the ore zone is about 4 miles from the pre-Cambrian granites to the west. No intrusive rocks have been found in the mine, nor is there evidence of any on surface that might indicate a genetic connection with the ore occurrence (Fig I). The schists strike N23°E and dip 75° to the northwest, which might indicate an overturned thrusting from the granites. In the upper levels, the echelon pattern in which the ore occurs was quite regular. no disturbance of the enclosing schist, or of any faulting that might contribute to the formation of the ore pattern was noted. There is a possibility that the ore zone may be on the axis of an isoclinal fold. Another interesting feature is the more or less typical zoning of minerals along the strike in each of the ore shoots (Fig 2). The north end of each shoot is enclosed by schist, while the south ends usually extend out at full width beyond the economic mining limits in a pyrite-quartz low-grade material. The plane of demarcation between ore and schist is very sharp, with little or no impregnation of sulphide in the schist, especially on the footwall side. The footwall schists are usually firm and strong, and vary from dioritic phases to fine-grained, lighter colored bands, almost silky in texture. The hanging wall for a width of 50 to 80 ft consists of alternating sheetings of chloritic and pyritic schists. The mine is now partly developed to the 920-ft level, with some diamond drilling from the 1150-ft station of No. 6 shaft. Economically there has been little change in nature or grade of ore from the top of the sulphides, about 200 ft below surface, to the bottom levels. There have been a few echelons in depth, just as there are in plan, and while a few shoots have had

Jan 1, 1949

By H. F. Mills

THE Iron King mine is 12 miles east of Prescott Arizona, in low foothills of the Agua Fria mining district. It was operated in 1906 and 1907, using gravity methods of concentration, mostly on oxide ores. In 1923 and 1924 shipments of sulphide ores were made to the Humboldt smelter. It remained inactive and stripped until 1936, when it was unwatered and sampled to the 400-ft level, the bottom at that time. In 1937 the Iron King Mining Co. purchased the mine and shipped oxide ores. During 1938 a bulk flotation plant of 140 tons daily capacity was erected. The mill has been enlarged and operations have been continuous since the mill first started. In July 1942, the Shattuck Denn Mining Corporation purchased the physical assets from the Iron King Mining Co., and since that time it has operated as the Iron King Branch of the Shattuck Denn Mining Corporation. Economic metals recovered are gold, zinc, silver, lead, a little copper, and fluxing pyrite. The ore occurs as a series of northward-dipping shoots arranged in echelon pattern, the series extending over a length of 3500 ft. Strike lengths of shoots vary from 60 to 600 ft, and widths from 3 ft to as much as 14 ft. The ore occurs in a sheared zone in pre-Cambrian chloritic schist. This schist belt is about 6 miles wide, and the ore zone is about 4 miles from the pre-Cambrian granites to the west. No intrusive rocks have been found in the mine, nor is there evidence of any on surface that might indicate a genetic connection with the ore occurrence (Fig I). The schists strike N23°E and dip 75° to the northwest, which might indicate an overturned thrusting from the granites. In the upper levels, the echelon pattern in which the ore occurs was quite regular, no disturbance of the enclosing schist, or of any faulting that might contribute to the formation of the ore pattern was noted. There is a possibility that the ore zone may be on the axis of an isoclinal fold. Another interesting feature is the more or less typical zoning of minerals along the strike in each of the ore shoots (Fig 2). The north end of each shoot is enclosed by schist, while the south ends usually extend out at full width beyond the economic mining limits in a pyrite-quartz low-grade material. The plane of demarcation between ore and schist is very sharp, with little or no impregnation of sulphide in the schist, especially on the footwall side. The footwall schists are usually firm and strong, and vary from dioritic phases to fine-grained, lighter colored bands, almost silky in texture. The hanging wall for a width of 50 to 8o ft consists of alternating sheetings of chloritic and pyritic schists. The mine is now partly developed to the 92o-ft level, with some diamond drilling from the 1150-ft station of No. 6 shaft. Economically there has been little change in nature or grade of ore from the top of the sulphides, about 200 ft below surface, to the bottom levels. There have been a few echelons in depth, just as there are in plan, and while a few shoots have had

Jan 1, 1947

By H. F. Mills

The Iron King mine is I2 miles east of Prescott Arizona, in low foothills of the Agua Fria mining district. It was operated in 1906 and 1907, using gravity methods of concentration, mostly on oxide ores. In 1923 and 1924 shipments of sulphide ores were made to the Humboldt smelter. It remained inactive and stripped unti1 1936, when it was unwatered and sampled to the 400-ft level, the bottom at that time. In 1937 the Iron King Mining Co. purchased the mine and shipped oxide ores. During 1938 a bulk flotation plant of I40 tons daily capacity was erected. The mill has been enlarged and operations have been continuous since the mill first started. In July 1942, the Shattuck Denn Mining Corporation purchased the physical assets from the Iron King Mining Co., and since that time it has operated as the Iron King Branch of the Shattuck Dcnn Mining Corporation. Economic metals recovered are gold, zinc, silver, lead, a little copper, and fluxing pyrite. The ore occurs as a series of northward-dipping shoots arranged in echelon pattern, the series extending over a length of 3500 ft. Strike lengths of shoots vary from 60 to 600 ft, and widths from 3 ft to as much as 14 ft. The ore occurs in a sheared zone in pre-Cambrian chloritic schist. This schist belt is about 6 miles wide, and the ore zone is about 4 miles from the pre-Cambrian granites to the west. No intrusive rocks have been found in the mine, nor is there evidence of any on surface that might indicate a genetic connection with the ore occurrence (Fig I). The schists strike N23°E and dip 75° to the northwest, which might indicate an overturned thrusting from the granites. In the upper levels, the echelon pattern in which the ore occurs was quite regular. no disturbance of the enclosing schist, or of any faulting that might contribute to the formation of the ore pattern was noted. There is a possibility that the ore zone may be on the axis of an isoclinal fold. Another interesting feature is the more or less typical zoning of minerals along the strike in each of the ore shoots (Fig 2). The north end of each shoot is enclosed by schist, while the south ends usually extend out at full width beyond the economic mining limits in a pyrite-quartz low-grade material. The plane of demarcation between ore and schist is very sharp, with little or no impregnation of sulphide in the schist, especially on the footwall side. The footwall schists are usually firm and strong, and vary from dioritic phases to fine-grained, lighter colored bands, almost silky in texture. The hanging wall for a width of 50 to 80 ft consists of alternating sheetings of chloritic and pyritic schists. The mine is now partly developed to the 920-ft level, with some diamond drilling from the 1150-ft station of No. 6 shaft. Economically there has been little change in nature or grade of ore from the top of the sulphides, about 200 ft below surface, to the bottom levels. There have been a few echelons in depth, just as there are in plan, and while a few shoots have had

Jan 1, 1949

By Tapponnier P

In North Vietnam, large ductile shear zones are observed along the Red river fault and the Dienbien fault. Left-lateral sense of the Red river shear zone is related to the direction of shortening E-W. NE dipping foliation planes is subvertical. Stretching lineation is subhorizontal ( 25¦). Left-lateral slip observed in the Oligocene Yansun granites demonstrates the major tectonic phase in Neogene, The stress field established from microfaults observed in triassic limestones, Oligocene granites and Neogene Conglomerates. Measurements of striations on fault mirors are used for calculating the stress tensor and for separating tectonic phases. Two tectonic phases in tertiary are separated : first tectonic phase related to the compressive direction E-W corresponds to the major tectonic phase represented by NW left-lateral shear zone. Second phase having the compressive direction N-S associated with the right-lateral movement of the Red-river fault zone opening of the Eastern sea and the Red-river and the Red-river delta is associated with the left-lateral movement along the Red-river.

Jan 1, 1990

By D. R. Snow

The year 1930 stands out in the petroleum industry as an exceptional one in many ways. It is one of the few years in its history during which crude oil production declined from that of the previous year in nearly every important producing district in the United States and in the world as a whole. World production of crude oil declined approximately 81,000,000 bbl., from 1,484,451,000 bbl. in 1929 to 1,403,500,000 bbl. in 1930. Production of crude oil in the United States declined approximately 111,000,000 bbl., from 1,007,323,000 bbl. in 1929 to a production of 896,265,000 bbl. in 1930. World production outside of the United States increased approximately 30,000,000 bbl., due principally to the increased production in Russia. This, together with the decided decrease of production in the United States, resulted in a smaller percentage of world production in the United States than in any other year since 1921. This declining production occurred in the face of the greatest visible supply in the form of potential production that the industry has ever known and was clearly the result of the great efforts put forward to restrict production, both by proration and by unitization. Throughout the year, developments along the lines of proration and unitization have overshadowed all other developments in the minds of those interested in the oil industry and will, no doubt, continue to do so more and more in the future, as it is quite evident that the industry cannot hope to maintain itself in a profitable position, without some rational plan of bringing about a better balance between supply and demand than has existed in the past. The successful operation of the Van field unitization agreement and the recently completed Kettleman Hills plan are indicative of what mag be expected in the future along this line. That real progress has been made in this direction is shown by the fact that total crude oil stocks in the United States were decreased by approximately 28,000,000 bbl. during the year 1930. This is the only year on record during which such a decrease of crude oil stocks was accompanied by a severely declining price structure. This reduction of crude stocks is apparently continuing even after the price has reached its present low level, indicating that there is no

Jan 1, 1931

By Jens P. Nielsen, W. H. Justice

This paper describes an improved acidizing technique which has been applied in acidizing gas wells in the La Gloria Field. Wells acidized in this manner exhibited a much greater increase in deliverahility than wells acidized in the conventional manner. The acid is injected into the well in small slugs separated by a small volume of high pressure gas. The acid and gas are displaced from the tuhing by high pressure gas to reduce the hydrostatic head on the well when the acid is recovered from the well. The well is opened for production as soon as the acid and gas are displaced. This procedure permits a very rapid recovery of the acid which results in large increases in the deliverability of the gas wells. It has been found advantageous in the acidization of gas injection wells to inject the high pressure gas directly after the acid without backflowing the acid out of the well. This practice has made it possible to inject the gas in the injection wells of this field with a much lower pressure differential. This reduces the horsepower required to inject the gas and also decrease:, the number of injection wells required per reservoir. INTRODUCTION The results obtained by acidizing gas wells ill the La Gloria Field have varied considerably in the past. For this reason. a planned study of the acidizing procedure was undertaken in order to obtain more consistent results. The Frio Sands of the La Gloria Field are rather permeable and it was not necessary to acidize many of the wells when they were originally completed. At the completion of an eight-year cycling program in several of the gas reservoirs, it became necessary to recomplete many wells in other reservoirs. It was found that the opan Flow potential of the wells recompleted in different sands was not as large as wells that were originally completted in that reservoir. A study of the drilling records of several of these wells indicated that the sands had originally been subjected to considerable hydrostatic drilling fluid overload while the well was being drilled to the deeper sands of the field. It is indicated that during this eight-year period, the drilling mud and water that were lost into the formation when the well was being drilled had formed a relatively impermeable Eone around the well bore. This impermeable zone around the well bore made it very difficult to obtain high deliverability wells when the original wells are recompleted in other zones. Muskat' has shown that in uniformly permeable and porous formations a zone of partial plugging one ft in radius around the well would drastically decrease the productivity of the well. The analysis for this problem shows that the production capacity of a well is very sensitive to the value of the permeability of the zone immediately surrounding the well bore. This is to be expected in view of the highly localized character of the pressure drop in a radial flow system about the well center. The reduction of the deliverability is not proportional to the thickness of the mud-affected zone as the major portion of the reduction in deliverahility IS caused hy the

Jan 1, 1952

By Tatiana Tronda

"The territory of Belarus is characterized by nonhomogeneous ground conditions. In some cases soft ground layers can reach tens of meters in depth. Application of piles and other conventional foundations is rather difficult and expensive in such complicated conditions. Alternatively for the first time dry concrete columns were applied to improve the saturated soft soils at two sites. As there is no design methods for calculation of bases improved by dry concrete columns static penetration and static load tests were carried out to check the bases on availability. Considerable increase of toe resistance and Young modulus was achieved for all types of soil. Practical application, technology and test results are described in the paper. According to comparative calculations the cost of foundations on the base improved by dry concrete columns can be 32-75% lower than the cost of conventional pile foundations depending on ground conditions.INTRODUCTIONPile foundations, sand cushions or dewatering are usually applied in complicated ground conditions which are caused by presence of saturated soft soils. If the depth of soft soils reaches 20 m or more, conventional foundations have limited application, high labor and construction cost. A rational solution in such conditions is a ground improvement of upper soft soils. It allows the loads to be transferred on upper ground layers and the stresses to be dissipated considerably before reaching underlying soft ground layers.One of the effective ground improvement methods for saturated soft soils is the reinforcing by dry concrete columns (Fig. 1). The method allows saturated soft soils to be compacted and be drained at the same time. As a result strength and deformation characteristics of natural soils improve (Tronda 2013, ?????? 2014).Unfortunately, there is no design and computing methods for the ground improvement by means of dry concrete columns. However, at present the methods are under development on the basis of theoretical and experimental researches.TECHNOLOGYThe dry concrete columns are fulfilled in pressed wells according to technology of vibrostamped piles. Wells are pressed by vibratory hammer with the closed ended casing (Fig. 2) that provides compaction of surrounding soft soils. Then the casing is filled with dry concrete mix (Fig. 3). The casing end remains on the design depth and the casing is removed by vibratory hammer. The removing of the casing with vibration enables compaction of dry concrete mix inside the well. Dry concrete mix drains surrounding saturated soft soils improving its properties and the compaction speeds up the consolidation process. Over time the dry concrete columns fasten absorbing water from surrounding saturated soft soils that is need for hydration of cement (Fig. 4, 5)."

Jan 1, 2016

By Ramon V. V de Araújo, Roberto B. E Trindade, Pablo R. Fica-Piras

"Lead has been reported to affect blood vessels and kidneys. It also produces adverse effects in the mental and physical development of children and nervous system of adults. It is also considered as a possible cause of cancer. Because of all these threats to the human life, the reduction of its environmental occurrence, by means of recycling, is an important additional advantage to the usual ones derived of the procedures of the secondary metallurgy: lead can be recycled several times maintaining its characteristics equivalent to the primary one.Furthermore, this way of producing the metal avoids the environmental impacts of primary lead melting. Also, as an additional advantage, it triggers the metallurgical process with a raw material in what we observe higher lead content than in the natural ores. Some of the potential sources for these purposes are: ashes, slags, electrode residues, anodic muds, spent electrolytes, solid and liquid wastes, industrial or automotive catalysts, worn-out or obsolete equipment components and/or final consumption products.About 40% of world’s lead production comes from automotive batteries, mainly composed of four parts: plastic box, electrolyte (diluted sulphuric acid), contacts and connectors of Pd-Sb and plates (PbSO4, PbO2 and PbO). The plates represent 75% of the total mass. Metallic parts can be melted at moderate temperatures and then refined. The remaining fraction, constituted by the non-metallic portions, can be recovered by hydro and electro-metallurgical routes. These routes are preferred instead of pyrometallurgical ones due to the ultimate emissions of lead particulates and sulphur dioxide.The principal constituent of the residual paste of batteries is the lead sulphate. In this process, the paste is treated in two stages: in the first, lixiviating with Na2CO3 (desulphurization of the paste), obtaining PbCO3 and Na2SO4; in the second, the lead carbonate is lixiviated with HNO3, producing Pb(NO3)2, soluble, that can be converted to metallic lead by electrolysis. The reaction of PbSO4 with Na2CO3 in aqueous solutions is fast: the global rate is limited by the diffusion of the carbonate ions inside the reaction medium."

Jan 1, 2003

By Benjamin Cebrian

Wall control blasting is an expensive and labor intensive operation. Obtaining a good design is a first step that is not enough to ensure desired results. Experience shows that designs are not always well implemented, not only in the contour blast itself, but also in surrounding production blasts that can affect the final pit wall. In this paper techniques and reference indicators are described in order to audit and evaluate if correct implementation of designs have been done.

Jan 1, 2013

By David Morrison

On the Corramandel Peninsula of New Zealand, the Waihi Gold Mine has undergone a major redevelopment. The upgrade included the construction of two very large overland belt conveyors, both rated for a capacity of 6000tph. The first of these conveyors (CVR2) traverses a total of 1600m over undulating terrain, including a significant section running through tunnels. A large hill is climbed, just after the mid-section of the conveyor run, before dropping back down prior the discharge point. The second of these conveyors (CVR8) traverses 1100m along an alignment with a horizontal curve, a number of vertical curves and a significant lift before the discharge point. The CVR8 conveyor also included a shuttling head pulley arrangement. The mine they service is inside the town of Waihi. The conveyor alignment runs through the town and out to the metallurgical process site on the outskirts of the municipal area. This paper documents the engineering process that took place in the design of these conveyors. The Martha Hill mine in Waihi, New Zealand is unique. The mine is placed in the township. Consequently there are quite stringent environmental limitations on the mine's operation. In [Figure 1] the proximity of the mine to the town is shown. In the top-centre of the photograph the alignment of the existing smaller overland conveyor can be seen leading from the mine to a tunnel through the hill in the background.

Jan 1, 2000

Nature: Man is but one of the creatures which in- habit the earth, a dust speck in the universe. Thinking man has been concerned with his place and purpose in the universe since the earliest Egyptian and Chinese philosophers. Ancient creeds, as well as modern religions and philosophies of life, were concerned with the same problem. While such considerations and concepts have been valuable, theoretical philosophizing and dogmatic concepts are inadequate for a satisfactory solution of world problems of today. The concepts of man and life and their ultimate purpose should be sought in the relations of intelligent man to man and their relation- ship to the physical world. The quintessence of nature's accomplishment-man- is also the greatest disturber of nature and the greatest enemy of his own kind. While his spirit and mind defy and overcome natural limitations, his physical self is controlled by the same basic biochemical laws that govern any other form of living matter. This paradoxical duality of human voluntary and involuntary relations to nature is the source of the perpetual conflict between mind and matter. Therefore, the higher the spiritual evolution and perfection of the individual's mind, the greater and deeper the conflicting elements in their expression; and conversely, the simpler the mind or the mental and spiritual heritage, the less is the individual concerned with the conflicting elements.

Jan 1, 1950

By Stephen LaBrooy, David Muir

Gold ores in the geologically more recent rocks are often associated with copper minerals which pose problems of high reagent consumption with conventional cyanidation practice. Many examples exist in northern Australia, Indonesia, Papua­New Guinea, Chile, and Brazil where, despite various treatment options (LaBrooy, 1992), the processing of oxide and transition ores is uneconomic either for copper or gold recovery. Hence, there is a need for a reagent which is selective for gold without leaching copper minerals. The ammonia-cyanide system appears to meet this criterion (Muir et al, 1989; LaBrooy et al, 1991; Costello et al, 1992; Hayes and Corrans, 1992) but it has proven difficult to optimise and apply to a variety of ores due to differences in the mineralogy and reactivity of ores and a lack of understanding of how the system works. Recent work on the mechanism, however, (Muir et al, 1993) has thrown a new light on the problem which should allow better process control. Ammonia­cyanide mixtures behave neither like free cyanide nor free ammonia and too much of either reagent in the mixture is detrimental. The key to the process is understanding how ammonia enhances gold extraction yet inhibits copper extraction in an essentially cyanide environment.

Jan 1, 1993

By Robert V. Whitman

INTRODUCTION Ideally, this paper should start by citing examples of slope failures in open pit mines during earthquakes. I do not know of any such examples, although - since my search of the literature has not been exhaustive - such examples may well exist. However, there certainly are many examples of devastating earthquake-induced landslides, and there is no reason why such landslides cannot occur at large open pits. Moreover, many of the actual earthquake-induced landslides have seriously affected mining operations in one way or another. Hence, this paper will treat earthquake-induced landslide phenomena in general, in the hope and expectation that the reader can apply this general knowledge to the specific problems associated with open pit mining. Ultimately, of course, the aim is to predict the likelihood of the occurrence of earthquake-induced landslides, and to delineate steps which can be taken to minimize the possibility of their occurrence. These aims can be achieved only imperfectly at the present time, for our knowledge concerning earthquake-induced landslides is still in an embryonic stage. Nonetheless, much useful knowledge does exist. In order to understand and apply this knowledge, it is necessary to: 1. Review the nature and extent of actual earthquake-induced landslides; 2. Have a grasp of the basic terminology and concepts of seismology; 3. Study the fundamentals of probability-based seismic risk analysis; 4. Appreciate the way in which earth materials behave during earthquake loadings; and 5. Have a general knowledge of the methods currently available for analyzing the dynamic response of slopes. Much of this paper is devoted to this necessary background. Information of practical use in connection with various classes of slope stability problems is assembled in the final sections. LANDSLIDES DURING PAST EARTHQUAKES Almost every earthquake in mountainous country, strong enough to be reported in the literature, has caused at least some landslides and rockfalls. Unless these slides or falls damage

Jan 1, 1971

By J. H. Ffolliott

ALL, of the prospects that later became mines in the Ducktown district were discovered prior to 1854, and most of them were exploited before the turn of the century. It is the purpose of this paper to discuss the exploration and current development of the Boyd mine, discovered in 1853. It is in the heart of the Ducktown Basin, in the extreme southeast corner of Tennessee, and is being developed by the Tennessee Copper Co. GEOLOGY The geology of the district has been fully described in many papers. Probably the most complete description is that of Emmons and Laney.1 The rocks of the district are considered to be of Lower Cambrian age and are a part of the Great Smoky formation, consisting mainly of interbedded graywacke and mica schist, in which the ore deposits occur. The ore bodies are included in an area of about 6 sq. miles, 2 miles wide and 3 miles long striking N. 45° E., and may be grouped into three general lode systems. The northeast system, including the East Tennessee, London and Burra Burra ore bodies, and the southeast group, comprising the Polk County, Mary and Calloway deposits, are all characterized by relatively high copper values. The ores of the central system, which includes the Eureka, Boyd, Old Tennessee and Cherokee ore bodies, are low in copper and high in total sulphide content. Boyd mine lies roughly halfway between the Old Tennessee and Eureka ore bodies [ ] and 2500 ft. in the hanging wall of the Burra Burra mine (Fig. 1). Elevation of the surface is about 1725 ft. above sea

Jan 1, 1942