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By W. F. Faragher

The principal equipment in the catalyst plants at Ludwigshafen-Oppau was inspected and is presented in the form of flow sheets for the manufacture of four of the principal catalysts. The equipment is in many cases of special design rather than stock items that was built by the company and modified in the coarse of the growth of the high-pressure synthesis of hydrocarbons in Germany. It is believed that if the manufacture of catalysts were to be undertaken elsewhere, the selection of equipment for the operations involved could be made successfully from the guidance furnished by this rather general report. Five additional catalysts are described, also. II. CATALYST 5058 FROM FRESH TUNGSTIC ACID In a supply tank of about 2,000 liters capacity, 500 kg. of tungstic acid (W03.H2O) that contains about 92-93 percent of W03 is dissolved at 60-70° C. in 1,500 liters of mother liquor. The solution is-effected by stirring for about 1-1/2 hours. The mother liquor is obtained from a previous, lot of catalyst and is first adjusted to a concentration of 13 percent 1H3 by passing in gaseous ammonia. The solution is allowed to stand without stirring for 1 hour, then is pumped into the saturating vessel through a cloth filter (three-quarters hr. to one hr.). The saturator is purged with H2S and thereafter the solution, which has been cooled to about 75° C., is heated in an atmosphere of hydrogen sulfide with stirring to about 70° C. This charge is slowly cooled to 50°, and then more rapidly to about 20° C. (time of cooling 6-7 hours).

Jan 1, 1946

By Manqiu Xu

"Ore grades are decreasing and ore deposits are becoming more complex. In order to make a sound economical decision about a mining project, metallurgical testwork must be carried out. A few large “representative” samples cannot represent the metallurgy of a large ore body and a large number of samples reflecting variation in ore head grades and in mineralization types must be obtained for proper metallurgical studies, including flowsheet development for a greenfield project. A relationship can be established between the recovery of valuable minerals and ore grade for each mineralization type. This relationship can be used to establish a correlation between values recoverable and values contained in the ore body that can include multiple pay metals. With this information, a sound economical decision can be made about the viability of a large mining development project.INTRODUCTIONThe demand for minerals today is historically high as many countries are being rapidly industrialized. The supply for these minerals is not necessarily running short. However, it is widely accepted that the world today is running short of the easy to mine and easy to process ore deposits. As ore grade is decreasing and ore mineralogy is becoming more complex, metallurgical testing must be fully conducted in order to make a sound economical decision about a mining project. For a high-grade and high-quality deposit, it is hard not to make a good profit even with low metal prices. For a low-grade and hard to process deposit, the profit margin is much lower and is dependent on the throughput and the recovery of valuable minerals. The recovery of valuable minerals is a function of ore grade and mineralogy and it must be experimentally determined for a given processing option.At Vale Base Metals Technology Development, metallurgical testing for an existing operation or brownfield project is termed as Ore Evaluation, while metallurgical testing for a greenfield project is termed as Flowsheet Development (Xu, 2011). In the past, metallurgical testing involved a few large composite samples for lab and pilot plant testwork. As ore deposit becomes less homogeneous and more variable, a few large composite samples cannot represent the metallurgy of a large ore body. In addition, useful information about the deposit such as zones of “impurities” or floatable rock minerals would not be obtained. Different processing strategies could have been developed if the locations and sizes of these zones were known in advance. For proper metallurgical studies, a large number of samples reflecting variation in ore head grades and in ore mineralization types must be used. A relationship can be established between the recovery of valuable minerals and ore grade for each mineralization type. This relationship can be used to estimate values recoverable in the ore body that can include multiple pay metals. Ultimately, the recovery verses ore grade relationship will be used in business decision-making."

Jan 1, 2013

By M. A. Hararah, T. Neesse, M. G. Farghaly, G. Proellss, P. Kaniut, W. Rubarth

ABSTRACT: This paper presents two new options for hydrocyclone control. Volume split control using a control valve in the overflow is applied for the stabilization of separation results at changing feed conditions. Controlled water injection to the conical part of the cyclone leads to the reduction of fine particles in the underflow. Hydrocyclone monitoring in both cases is performed by optical sensors that indicate the spray angle of the underflow. Applications in mineral processing for desliming, classification in closed-circuit grinding, and dewatering are demonstrated.

Jan 1, 2011

By A. G. Buyers, J. Chilton, W. E. McKee

STUDIES in the high-temperature separations chemistry of thorium-uranium fuels are complicated by the corrosive nature of these molten metal systems at 1700°C. Separations research pointed toward the removal of fission products from irradiated alloys has included a frozen salt-bed technique which minimizes container reaction with molten metal. The procedure consists of high-frequency induction melting of the metal sample which is supported by a vertical column of unmelted salt. The molten alloy melts its immediate salt environment and as it slowly falls down through the column, many of the fission-product poisons are transferred into the fused salt environment. The molten salt-metal zone is encompassed at all times by unmelted salt, preventing container contact. EXPERIMENTAL Experimental methods were separated into three parts: salt-bed preparation, melting, and analytical evaluation. A) Bed Preparation—The procedure for casting calcium-fluoride briquettes was to compress the powdered salt at 5,000 to 10,000 psi and place this compact in a graphite crucible. This assembly was inserted into a vacuum system and surrounded by an alumina crucible as well as molybdenum, tantalum, or stainless-steel foil thermal-radiation shields. The pressure was reduced and the crucible heated under vacuum to about 800°C with the fore pump operating. Argon was then admitted to about 0.8 atm and heating continued until the CaF2 had melted 5 min at the melting point seemed satisfactory). Apparatus used included a 1-in. graphite crucible with 1/8-in. walls, 1-in. ID in a 2-in. induction coil, and a 6-kw Ajax high-frequency converter. B) Melting—Calcium-fluoride briquettes, 1 in. in diam and 1/2 to 1 in. thick, were prepared and vertically stacked to obtain the desired column length. An irradiated alloy sample (nut = 10") was placed on top of the salt column and the assembly was connected to the vacuum system. After evacuation of 5 to 10 , purified argon was admitted and the system flushed twice. The final argon pressure was about 0.8 atm. The sample was heated by induction at a power of about 6.5 kw. It then melted its way down through the salt and freely dropped into a small alumina crucible. The molten metal is followed during its downward course by the induction coil which is mounted upon a power-driven machine-threaded shaft. Experimental conditions used in the foregoing work

Jan 1, 1960

WHAT DOES "MAGNETIC" MEAN? The word magnetic has several meanings. When used, as it usually is, without qualification one is often unable to tell which meaning is intended. 1. A body is magnetic which has power to attract iron magnetically. Such is a lodestone or magnet, either permanent or not. This is an active sense or meaning in that the body itself does the attracting or is .magnetic. 2. A body is magnetic which may be made to attract iron magnetically, as the iron core of an electro-magnet when not magnetized by the current. This is a potentially active meaning, the body being capable of becoming a magnet. 3. A body is magnetic which has the property of being. attracted by a magnet magnetically. Such are iron, cobalt, nickel, magnetic oxide of iron, magnetic alloys, etc. This is a passive meaning, the attracting being done by the actively magnetic body. With these three meanings to choose from, one must usually make a guess based on previous knowledge as to which is the right one. Would it

Jan 5, 1914

By George H. K. Schenck

The greatest difficulty in choosing solutions to environmental problems ill a free market economy (such as ours) stems from two factors: adverse effects of pollution are largely external to the producer, and expenditures made that improve the environment result in benefits that are free to all, These two factors are sufficient to explain why the solution to many environmental problems is to be found in public action. Such action is most likely to be economic- ally efficient if it can be carried out so that industry retains the freedom to make decisions based on the free market. Two examples-a zoned discharge fee and innovation of recycling systems-illustrate the type of changes in the mineral industry that would lead to an improved environment. The first requires that ownership of the relevant public resources be vested in control agencies. The second indicates that profit opportunities existing in solid waste recycling should facilitate innovation. Both concepts can reduce environmental loadings but will require imaginative thought from persons in the mineral industries.

Jan 1, 1971

By W. Rogers

Blast-induced rock mass displacement can have a significant impact on ore loss & dilution. The mischaracterisation of the grade boundaries both prior to, as well as a result of blasting can lead to significant financial losses on account of ore loss and dilution. Ore dilution occurs when waste material is miscategorised as ore and sent for processing or stockpiling, diluting the run of mine head grade and recovery. Ore loss takes place when valuable mineral is miscategorised as waste and sent to the waste dumps, thus never being processed and recovered. Extensive research has been conducted at the University of Queensland over the last fifteen years to understand the impact of blast movement on ore loss and dilution. Recent outcomes of this research have developed innovative tools and techniques to measure and model blast movement. These techniques have been implemented at Ahafo gold mine in Ghana to understand blast movement dynamics and to implement solutions to reduce blast-induced ore loss and dilution. These solutions are validated through controlled trials and have been incorporated into site standard operating procedures to sustain the benefits.

Jan 1, 2012

By E. E. Schumacher, G. S. Phipps, H. M. Bouton

The seriousness of the present tin scarcity has stimulated large consumers of this vital metal to develop drastic conservation measures in order to extend the available supplies to cover the emergency period. By devising new soldering methods and alloys the Bell System has contributed a substantial share in the tin conservation effort. Fortunately, the changes, as far as can be determined now, have not introduced weakness into the soldered joints. Some of the new procedurcs were already in the process of development at the onset of the emergency, while others were devised under its stress. In some instances, the newly developed solders were found to be more difficult to use than the alloys previously available, and would not have been introduced under normal conditions. One major change made that previously had been under consideration will result in large savings of tin. Unless service difficulties are encountered, this modification gives promise of remaining after the emergency has passed. The change involves a reduction in the amount of solder placed on a wiped joint between the cable sheath and the sleeve. Instead of the customary full sized wiped joint, a wipe of fillet proportions is formed. Through this change, a solder saving of more than 60 per cent per joint can be realized. Plumbers and cable splicers for many years have joined lead pipes and cable sheath by a soldering process called " wiping." The name is an apt description of the operation. For a wiped joint, the sections to be united are heated by molten solder poured over their surfaces, and the resulting semiliquid mass is manipulated by wiping with cloth pads to a well rounded symmetrical form like the one shown in Fig. I. The operation requires considerable skill on the part of the splicer and close control of the composition of the solder. At first consideration, the problem of tightness in such joints seems simple but experience shows that even under the best conditions the fissures frequently found in the solder occasionally link and form a path that allows leakage to occur. In telephone cables not maintained under gas pressure, such leaks permit the entrance of water, which wets the paper-covered conductors and thereby impairs the insulation value and causes service interruptions. Ry going to an extreme and wiping off all the solder in excess of a fillet, it has been found that many causes of porosity are eliminated. Figs. 2 and 3 show cross sections of joints wiped in the old and the new ways. The saving in solder, and consequently in strategic tin, is evident. The field splicing forces find that joints are easier to make by the new method and are less likely to be porous. The metallurgical considerations that are responsible for the success of the fillet wipe are of interest. Much has been written about the wiping process of soldering cable joints and the many requirements of a good wiping solder have frequently been listed. The success of the procedure described

Jan 1, 1943

By R. W. Gurry

In the course of a series of measurements of the rate of diffusion of carbon in austenite at about 960°C. (1760°F.) and III0°C. (2030°F.), it became necessary to determine carbon concentration when austenite is saturated with graphite, because of indications that the hitherto accepted value of the solubility of graphite in this temperature range is too low. Specimens of carbonyl iron were saturated at temperature in a hydrogen-toluene atmosphere which was in equilibrium with graphite. The carbon conteDt of the steel was measured either by combustion or by the loss of weight after substantially complete decarburization in an atmosphere of hydrogen saturated at room temperature with water vapor. The absence of carbide or graphite as a phase at temperature was demonstrated by microscopic examination of saturated specimens that had been drastically quenched, The mean result of concordant ments-—taeats-is-^that gamma iron saturated with respect to graphite contains 1.39 per cent carbon at 957°C .(i755°F.) and 1.89 per cent at III0°C. (2030°F.). These two values, plotted along with what appears from the literature to be the best value (0.69 per cent) at the iron-graphite eutec-toid temperature (738°C. or I360°F.), yield a curve that is almost linear, and which, continued upward through a short interval, leads to a limiting solubility of 1.98 per cent at the iron-graphite eutectic temperature II35°C. (2075°F.) instead of the commonly accepted value of about 1.7 per cent. Experimental Procedure The samples of carbonyl iron, with the exception of those for microscopic examination, were cylinders 3.8 cm. long, 0.475 cm. in diameter. They were placed in a graphite holder and suspended in a vertical furnace, the temperature of which was controlled precisely by means of the resistance of the platinum winding.' In the empty furnace the range of temperature over a distance of 4 cm. at the heat center was 9°C. (I6°F.) but at a given location the temperature remained within +o.5°C. (o.9°F.); it was measured by inserting a platinum-rhodium couple calibrated at the melting point of palladium, 1555°C. Since the presence of the sample probably improved the uniformity of temperature, it was decided to consider the average temperature of the sample to be 3°C. lower than the maximum measured in the empty furnace with the same setting of the controller. Data were obtained in the vicinity of two temperatures, 960°C. (I760°F.) and III0°C. (2030°F.). The samples for microscopic examination, 2.2 cm. long, 0.475 cm. in diameter, were suspended individually on pure iron wire; for these no temperature correction was applied. The carburizing gas passed into the furnace was dry, oxygen-free hydrogen saturated at room temperature with toluene; this quickly produced on the

Jan 1, 1942

By G. S. Phipps, E. E. Schumacher, G. M. Bouton

THE seriousness of the present tin scarcity has stimulated large consumers of this vital metal to develop drastic conservation measures in order to extend the available supplies to cover the emergency period. By devising new soldering methods and alloys the Bell System has contributed a substantial share in the tin conservation effort, Fortunately, the changes, as far as can be determined now, have not introduced weakness into the soldered joints. Some of the new procedures were already in the process of development at the onset of the emergency, while others were devised under its stress. In some instances, the newly developed solders were found to be more difficult to use than the alloys previously available, and would not have been introduced under normal conditions. One major change made that previously had been under consideration will result in large savings of tin. Unless service difficulties are encountered, this modification gives promise of remaining after the emergency has passed. The change involves a reduction in the amount of solder placed on a wiped joint between the cable sheath and the sleeve. Instead of the customary full sized wiped joint, a wipe of fillet proportions is formed. Through this change, a solder saving of more than 60 per cent per joint can be realized. Plumbers and cable splicers for many years have joined lead pipes and cable sheath by a soldering process called "wiping." The name is an apt description of the operation. For a wiped joint, the sections to be united' are heated by molten solder poured over their surfaces, and the resulting semiliquid mass is manipulated by wiping with cloth pads to a well rounded symmetrical form like the one shown in Fig. I, The operation requires considerable skill on the part of the splicer and close control of the composition of the solder. At first consideration, the problem of tightness in such joints seems simple but experience shows that even under the best conditions the fissures frequently found in the solder occasionally link and form a path that allows leakage to occur. In telephone cables not maintained under gas pressure, such leaks permit the entrance of water, which wets the paper-covered conductors and thereby impairs the insulation value and causes service interruptions. By going to an extreme and wiping off all the solder in excess. of a fillet, it has been found that many causes of porosity are eliminated. Figs. 2 and 3 show cross sections of joints wiped in the old and the new ways. The saving in solder, and consequently in strategic tin, is evident. The field splicing forces find that joints are easier to make by the new method and are less likely to be porous. The metallurgical considerations that are responsible for the success of the fillet wipe are of interest. Much has been written about the wiping process of soldering cable joints and the many requirements of a good wiping solder have frequently been listed. The success of the procedure described

Jan 1, 1943

By H. M. Bouton, G. S. Phipps, E. E. Schumacher

The seriousness of the present tin scarcity has stimulated large consumers of this vital metal to develop drastic conservation measures in order to extend the available supplies to cover the emergency period. By devising new soldering methods and alloys the Bell System has contributed a substantial share in the tin conservation effort. Fortunately, the changes, as far as can be determined now, have not introduced weakness into the soldered joints. Some of the new procedurcs were already in the process of development at the onset of the emergency, while others were devised under its stress. In some instances, the newly developed solders were found to be more difficult to use than the alloys previously available, and would not have been introduced under normal conditions. One major change made that previously had been under consideration will result in large savings of tin. Unless service difficulties are encountered, this modification gives promise of remaining after the emergency has passed. The change involves a reduction in the amount of solder placed on a wiped joint between the cable sheath and the sleeve. Instead of the customary full sized wiped joint, a wipe of fillet proportions is formed. Through this change, a solder saving of more than 60 per cent per joint can be realized. Plumbers and cable splicers for many years have joined lead pipes and cable sheath by a soldering process called " wiping." The name is an apt description of the operation. For a wiped joint, the sections to be united are heated by molten solder poured over their surfaces, and the resulting semiliquid mass is manipulated by wiping with cloth pads to a well rounded symmetrical form like the one shown in Fig. I. The operation requires considerable skill on the part of the splicer and close control of the composition of the solder. At first consideration, the problem of tightness in such joints seems simple but experience shows that even under the best conditions the fissures frequently found in the solder occasionally link and form a path that allows leakage to occur. In telephone cables not maintained under gas pressure, such leaks permit the entrance of water, which wets the paper-covered conductors and thereby impairs the insulation value and causes service interruptions. Ry going to an extreme and wiping off all the solder in excess of a fillet, it has been found that many causes of porosity are eliminated. Figs. 2 and 3 show cross sections of joints wiped in the old and the new ways. The saving in solder, and consequently in strategic tin, is evident. The field splicing forces find that joints are easier to make by the new method and are less likely to be porous. The metallurgical considerations that are responsible for the success of the fillet wipe are of interest. Much has been written about the wiping process of soldering cable joints and the many requirements of a good wiping solder have frequently been listed. The success of the procedure described

Jan 1, 1943

By R. W. Gurry

In the course of a series of measurements of the rate of diffusion of carbon in austenite at about 960°C. (1760°F.) and III0°C. (2030°F.), it became necessary to determine carbon concentration when austenite is saturated with graphite, because of indications that the hitherto accepted value of the solubility of graphite in this temperature range is too low. Specimens of carbonyl iron were saturated at temperature in a hydrogen-toluene atmosphere which was in equilibrium with graphite. The carbon conteDt of the steel was measured either by combustion or by the loss of weight after substantially complete decarburization in an atmosphere of hydrogen saturated at room temperature with water vapor. The absence of carbide or graphite as a phase at temperature was demonstrated by microscopic examination of saturated specimens that had been drastically quenched, The mean result of concordant ments-—taeats-is-^that gamma iron saturated with respect to graphite contains 1.39 per cent carbon at 957°C .(i755°F.) and 1.89 per cent at III0°C. (2030°F.). These two values, plotted along with what appears from the literature to be the best value (0.69 per cent) at the iron-graphite eutec-toid temperature (738°C. or I360°F.), yield a curve that is almost linear, and which, continued upward through a short interval, leads to a limiting solubility of 1.98 per cent at the iron-graphite eutectic temperature II35°C. (2075°F.) instead of the commonly accepted value of about 1.7 per cent. Experimental Procedure The samples of carbonyl iron, with the exception of those for microscopic examination, were cylinders 3.8 cm. long, 0.475 cm. in diameter. They were placed in a graphite holder and suspended in a vertical furnace, the temperature of which was controlled precisely by means of the resistance of the platinum winding.' In the empty furnace the range of temperature over a distance of 4 cm. at the heat center was 9°C. (I6°F.) but at a given location the temperature remained within +o.5°C. (o.9°F.); it was measured by inserting a platinum-rhodium couple calibrated at the melting point of palladium, 1555°C. Since the presence of the sample probably improved the uniformity of temperature, it was decided to consider the average temperature of the sample to be 3°C. lower than the maximum measured in the empty furnace with the same setting of the controller. Data were obtained in the vicinity of two temperatures, 960°C. (I760°F.) and III0°C. (2030°F.). The samples for microscopic examination, 2.2 cm. long, 0.475 cm. in diameter, were suspended individually on pure iron wire; for these no temperature correction was applied. The carburizing gas passed into the furnace was dry, oxygen-free hydrogen saturated at room temperature with toluene; this quickly produced on the

Jan 1, 1942

By A. R. Hekmat

Hypereutectic Al-Si alloys are used in applications that require high resistance to wear and corrosion, hardness and low coefficient of thermal expansion, To maximize the properties of these alloys, semi-solid processing can be utilized to modify the solidification structure of the primary silicon crystals as well as to reduce microsegregation and porosity, The transformation and spheroidization of primary Si crystals by shearing in the semi-solid state are not fully understood as they precipitate in the presence of other alloy phases, The objective of the present work is the determination the rheological characteristics of A390 (Al-17%Si-4,5%Cu-0.5%Mg) alloy using a Couette type (Haake RV12) viscometer and examining the microstructural evolution during continuous cooling and isothermal shear rate experiments, The effect of shear rate, solid fraction (temperature) and morphological evolution of the silicon crystals are investigated.

Jan 1, 2005

By Victor Homerberg

A STUDY of the correlation of the mechanical properties, and of the microstructure with the heat treatment of 60-40 brass has been confined, heretofore, to the rolled or extruded material as received from the manufacturer. The results obtained by Babson and Buhler,1 Bengough and Hudson,2 Stead and Stedman,3 and Brayton4 have been confined to the treatment of the material as received. No attempt was made to get the material into a given condition and then to work from this basis. To start with a given structure would have the decided advantage of making the work independent of the original condition, hence, to make the results reproduceable. In a previous paper, it was shown, in connection with the study of the transformation that occurs at about 470° C., that if specimens were quenched to produce the beta structure and then reheated, the beta would begin to break down, at approximately 200° C., into a very finely divided alpha. It was predicted that important results might be obtained if test pieces were to be given a similar double heat treatment and then tested for the mechanical properties as well as a study of the microstructure. The material used in the present investigation was a ¾ -in. round bar of extruded muntz metal of the following composition: Copper, 61.05 per cent.; zinc (by difference), 38.90 per cent.; lead, 0.05 per cent.; iron, trace; tin, nil.

Jan 3, 1924

By S. Aktas

The present work describes an investigation of a hydrometallurgical process for the recovery of mercury from spent silver oxide button cells. The cell paste was leached in nitric acid to solubilize silver, mercury and zinc. The optimum leaching conditions, in which mercury is entirely converted to Hg2+ ions and, therefore, does not coprecipitate with silver chloride during treatment with potassium chloride solution, were 1.0 M HNO3, 45° C, 1 hour and 200 rpm. After the silver was removed from the solution, mercury was cemented out with zinc powder with an efficiency greater than 99%. In the cementation experiments, the amount of zinc powder, shaking rate, temperature and solution pH were investigated in detail. The mercury recovery (%) increased as the amounts of zinc powder and the temperature were increased. Zinc hydroxide was precipitated from the waste solution by the addition of sodium hydroxide. The Zn(OH)2 precipitate was then converted to zinc oxide. The proposed process is proven to be simple, straightforward and environmentally friendly.

Nov 1, 2011

By S. Aktas

The present work describes an investigation of a hydrometallurgical process for the recovery of mercury from spent silver oxide button cells. The cell paste was leached in nitric acid to solubilize silver, mercury and zinc. The optimum leaching conditions, in which mercury is entirely converted to Hg2+ ions and, therefore, does not co-precipitate with silver chloride during treatment with potassium chloride solution, were 1.0 M HNO3, 45° C, 1 hour and 200 rpm. After the silver was removed from the solution, mercury was cemented out with zinc powder with an efficiency greater than 99%. In the cementation experiments, the amount of zinc powder, shaking rate, temperature and solution pH were investigated in detail. The mercury recovery (%) increased as the amounts of zinc powder and the temperature were increased. Zinc hydroxide was precipitated from the waste solution by the addition of sodium hydroxide. The Zn(OH)2 precipitate was then converted to zinc oxide. The proposed process is proven to be simple, straightforward and environmentally friendly.

Jan 1, 2011

By Murat Baydogan

Effect of retrogression and reaging treatment on hardness and stress corrosion cracking resistance of 7075 aluminum alloy was investigated. As received 7075 alloys in T6 temper condition were retrogressed at 170, 220, 240 and 380°C for different durations between 15 s and 60 min. Subsequent reaging was made at the T6 aging condition. Treated materials exhibited higher hardness and better stress corrosion cracking resistance than T6 temper in a wide range of retrogression temperature and time. The highest hardness was obtained after retrogression at 170°C for 210 s followed by reaging, corresponding to 20% hardness improvement. Improvement in stress corrosion cracking resistance of the alloy by as much as 85% was also observed. In this paper, improvements in hardness and stress corrosion cracking resistance are discussed on the basis of the microstructural changes during retrogression and reaging treatment.

Jan 1, 2006

By S. S. Wang

Dialkyldithiophosphinates are a new class of flotation collectors for base metal sulfide ores. Structurally, they are quite different from the conventional collectors such as mercaptans, xanthates, thionocarbamates and dithiophosphates. Collectors Structures [Mercaptans R-SHS Xanthates R-OCS-M+ Thionocarbamates R-OCNH-R Dithiophosphates 2 R-CCNH-R' Dithiophosphinates (R) 2-PS-M+ ] In the above structural formula, R and R' stand for a hydrocarbon radical, and M+ is an alkali metal or ammonium cation.

Jan 1, 1982

By Y Cui, G Cao, H Zong, J Zheng, J Wang, S Yue, J Zhao, B Li

The iron (Fe) concentration in nickel slag is high, making its recovery and utilisation a hot and challenging topic. In the nickel smelting process, using CaO instead of SiO2 to adjust slag’s composition, and then directly reducing Fe from the output of molten slag is a more feasible method in practice for Fe recovery in nickel slag. The adjustment of slag’s composition in the nickel smelting process will have an impact on the distribution of impurity elements such as Pb, Zn, and As. In this paper, the slag adjustment of nickel smelting process was carried out with the oxygen-enriched topblowing system. The distribution of impurity elements in the smelting products with each composition slag was conducted by using thermodynamic software. Experimental verification was performed with rich oxygen top-blowing, and the distribution characteristics of impurity elements in the smelting products were characterised to explore the differences in mineral phases of impurity elements with each smelting conditions, elucidating the distribution patterns of Pb, Zn, and As in each phase. The results indicate that after slag adjustment, impurity elements are more easily to volatilisation and removal into the gas, reducing their total concentration in slag and matte. In the slag, the existence form of Pb, Zn is changed from silicate to ferrate, and As is changed from arsenate to low-valent arsenic oxide. It is easier to decompose the impurity-containing mineral phase and remove the impurity elements in the subsequent iron extraction process.

Jun 19, 2024

By Patricia Pride, Kurt Bettger, Jack Raymer

"INTRODUCTION The Jefferson Barracks Tunnel is in the final stages of design and is expected to go out to bid in the summer of 2016. The project is located in south St. Louis County along the west bank of the Mississippi River, about 13 km downstream of the St. Louis Gateway Arch. The project consists of a deep sanitary sewer tunnel, a deep pump station and several intakes. The intakes will divert sanitary flows into the tunnel and the tunnel will convey the flows by gravity to the Lemay No. 3 Pump Station, which will pump them up into the Lemay Waste Water Treatment Plant. The tunnel is about 5.4 km long and will be lined with 84-inch (2.1 m) fiberglass pipe. It drops at a gradient of 0.1 percent from south to north and will be bored through strong limestone using a hard-rock tunnel boring machine (TBM). The diameter of the TBM is anticipated to be about 3.4 m. The Owner’s original concept was for a relatively shallow tunnel so as to minimize construction and pumping costs. The preferred alignment ran close to the river, next to the existing force main, which was to be abandoned. Keeping the tunnel close to the force main would reduce the amount of shallow sewer work needed to connect the existing feeder sewers to the new tunnel. Several geotechnical investigations were performed, with shallowly focused geophysics and the borings all going exactly down the conceptual tunnel depth. Limestone bluffs run along the Missouri side of the river. These bluffs are pockmarked by sinkholes and riddled with karst. Large, well-known caves occur both north and south of the alignment. Karst features, including deep crevices and possible caves, were found in those early geotechnical investigations. Many of these features extended well below the level of the Mississippi River and would have been encountered by the tunnel. If a large crevice or cave were encountered, then the inflow of mud and water into the tunnel could have been large and possibly uncontrollable. Something had to be done to mitigate this situation. Pre-excavation grouting was considered, but the program would have been huge and extremely expensive. Using a closed-face TBM with bolted and gasketed lining was also considered, but that too was both risky and extremely expensive. The Owner could have abandoned the tunnel altogether and built a new force main, but that would have brought a whole new set of problems and was undesirable to the Owner. The last option was to move the tunnel away from the karst."

Jan 1, 2016