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Kalgoorlie Consolidated Gold Mines Pty Ltd is currently developing the 'Super Pit' gold mine in the mining area known as the Golden Mile adjacent to the city of KalgoorlieBoulder, Western Australia. The presence of numerous abandoned mine workings and complex structural geology has required considerable geotechnical input into the determination of the optimum pit slope geometries for both interim and ultimate pit slopes. Slope design is based on detailed site investigation and stability analysis which is balanced with historical operational experience. This paper discusses the process of determining the optimum pit slope angles for each of the stages of the west wall of the 'Super Pit'. The risks associated with slope instability are discussed for each stage.

Jan 1, 1994

By WALTER M. DAKE

WITH the renewal of the contract between bituminous miners and operators, whereby a period of three years is assured without the devastating effect of irregularity of operation due to general strikes; and, with the increasing comprehension on the part of the large consumers as to the stabilizing effect of adequate storage upon prices; the coal industry has reached that period of its history in which permanence of purpose towards necessary changes is being crystallized, and these changes accomplished by the industry. It is to be hoped that during this era the phrase- " Our National Coal Problem "-will be relegated to the limbo of' antiquated expressions. That this epoch is upon us is evinced by the fact that operators are turning to consolidations, whereby financially sound companies will acquire smaller production units and place themselves in position to maintain constant supervision and control of their development and output; and, as further proof of the arrival of these changes, may be cited the entrance of additional members of the engineering profession into the many phases of management and operation, where- by the cost per ton of output will be, constantly reduced through the increasing use of modern methods and equipment. As an instance, attention is specifically called to the developments in mechanical loading, proposed and actual continuous underground transportation systems and betterment in methods of preparation.

Jan 1, 1924

By T. G. Pedro, Q. Gonzalo, R. E. Roberto

Anionic surfactants, such as oleic acid and sodium oleate (OLE), and cationic surfactants, such as dodecyl amine-hydrochloride (DDA), are used as flotation collectors of spodumene. However, recovery is poor even if activating ions are used because gangue minerals are also activated. Some reports demonstrate that OLE/DDA mixtures act as a selective collector to enhance spodumene recovery. From mostly macroscopic tests, it has been argued that anionic OLE and cationic DDA form electroneutral complexes, which are adsorbed on the mineral surface through chemisorption; however, no molecular evidence has been presented. Therefore, the adsorption mechanisms of the collector mixtures remain mostly unknown. It seems necessary to first study the behaviour of these surfactants confined in salt solutions, to determine auto-associations when they are pure and cross-associations when mixed, the transition from monomers to micelles, and the structure of the micelles and the effects of pH, temperature and concentration. In this paper, ab initio calculations are first used to determine the surface charge distribution of OLE and DDA separately. Then molecular dynamics simulations are used to determine the conformation, aggregation, and diffusion of these pure and mixed surfactants in freshwater and saltwater with the ionic strength of seawater in a pH range. In particular, it is interesting to determine the various associations that result in mixtures of both surfactants and the impact of alkali and alkaline earth metal cations on the structures formedp. Cations influence the order of the structure and orientation of water dipoles, reducing the mobility of water, ions, and surfactant molecules. This knowledge is critical to improve the molecular understanding of the adsorption mechanisms on minerals. Keywords: Computer simulation, molecular dynamics, flotation, collectors, saltwater

Jan 1, 2020

By Greg Sanders, Bill Lueck, Michael Gilbert, Mahmood Khwaja

"The city of Minneapolis contracted with CDM Smith to update and provide a conceptual design for improvements to mitigate surcharge flooding in the Central City Storm Water Tunnel System (CCSTS). As a part of the project, CDM Smith conducted a field survey and condition assessment of the existing tunnel system. Information from the survey was then used to update the existing XPSWMM model and develop system wide alternatives.The CCSTS provides storm-water runoff drainage for nearly the entire area of the city’s downtown commercial district. The system consists of deep storm-water tunnels constructed in the St. Peter Sandstone, approximately 21 m (70 ft) below the street’s surface. The primary tunnels comprising the Central City storm water tunnel system are located below Hennepin Avenue, Nicollet Mall, Lesalle Avenue, Marquette Avenue South, 2nd Avenue South, South 5th Street, Washington Avenue South, Portland Avenue South, 2nd Street South, and Chicago Avenue South, as shown in Fig. 1. This network of tunnels conveys the runoff from a 305-acre tributary area that is generally bound by Hennepin Avenue and 1st Avenue North to the east, 12th Street to the south, 4th Avenue South and 7th Avenue South to the west, and 2nd Street South. These tunnels were constructed between 1936 and 1940, except for the Marquette Avenue South tunnel, which was constructed between 1963 and 1964.The CCSTS operates as a gravity flow system. These tunnels were constructed within the St. Peter Sandstone layer of bedrock and emerge from the bedrock at the Mississippi River below St. Anthony Falls. The Central City and the adjacent Chicago Avenue tunnel system converge into a single outfall at the Mississippi River. The runoff discharges from the converged outfall to a side channel of the Mississippi River, called a tailrace, located near the Guthrie Theater. The Minneapolis Division of Surface Water and Sewers provided 32 historic plats detailing the plan and profile of the tunnel system.The tunnel plans show nine different cross-section configurations. Eight configurations within the overall system generally show the same geometric “cathedral” shape with the inside dimensions varying from 1.2 to 1.8 m (4 to 6 ft) in width and 1.8 to 2.4 m (6 to 8 ft) in height. For analysis, these eight configurations were reduced to three configurations with regards to tunnel liner, cross-sectional area and support. For simplicity, the three configurations are described according to the three types of tunnel support used during construction: none required, light timber and heavy timber"

Jun 1, 2019

By Henry Seltz, Cyril Wells, Hugh J. MacDonald

Several investigators have measured the heat capacity of cementite, using different methods of attack, but the agreement between the values obtained cannot be considered good. Naeserl has made measurements of "average heat capacities" of iron carbide between 1026" and 85" K., using a water calorimeter. His computed true specific heat at 78.1" K. is 11.22 cal. per gram-formula mass, which, if correct, is much too high for any reasonably accurate extrapolation to 0" K. The cementitc used by Naeser was obtained from a steel containing 0.9 per cent carbon, by electrolytically dissolving out the iron in a neutral bath of ferrous chloride. The cementite remained as a coarse, crystalline, gray powder. Andes2 has measured the specific heat of iron carbide, from 102" to 323" K., as it exists in steel. The specific heats of several slugs of steel of known iron carbide content were determined, and the specific heat of the iron carbide (Fe3C) calculated by plotting specific heat versus percentage of carbon, and extrapolating to pure Fe3C (6.7 per cent C). The heat-capacity values for temperatures below 100" K. were obtained by comparing the temperature-specific heat curve for Fe3C to that of Fe. Since the two were very similar in the range examined experimentally and approach more closely at low temperatures, it was assumed that near the absolute zero the form of the curve for Fe3C would be similar to that of Fe. Andes calculates for the entropy of Fe3 C,S298 = 23.55 e.u. The heat of formation of Fe3C has been studied by several workers. Kelley3 has reviewed these measurements and calculations, and selects those of Roth* and Naeser6 as worthy of most consideration. Roth has given AH = 5400 cal. + 30 per cent as a result of his own and other work. Naeser has determined the heat of formation from Fe and different forms of carbon, and for graphite (0) he finds AH = 5600 cal. Kelley accepts the rounded figure AH = 5500 as the heat of formation at 298.1" K., but this value is quite uncertain.

Jan 1, 1940

By Henry Seltz, Hugh J. MacDonald, Cyril Wells

Several investigators have measured the heat capacity of cementite, using different methods of attack, but the agreement between the values obtained cannot be considered good. Naeserl has made measurements of "average heat capacities" of iron carbide between 1026" and 85" K., using a water calorimeter. His computed true specific heat at 78.1" K. is 11.22 cal. per gram-formula mass, which, if correct, is much too high for any reasonably accurate extrapolation to 0" K. The cementitc used by Naeser was obtained from a steel containing 0.9 per cent carbon, by electrolytically dissolving out the iron in a neutral bath of ferrous chloride. The cementite remained as a coarse, crystalline, gray powder. Andes2 has measured the specific heat of iron carbide, from 102" to 323" K., as it exists in steel. The specific heats of several slugs of steel of known iron carbide content were determined, and the specific heat of the iron carbide (Fe3C) calculated by plotting specific heat versus percentage of carbon, and extrapolating to pure Fe3C (6.7 per cent C). The heat-capacity values for temperatures below 100" K. were obtained by comparing the temperature-specific heat curve for Fe3C to that of Fe. Since the two were very similar in the range examined experimentally and approach more closely at low temperatures, it was assumed that near the absolute zero the form of the curve for Fe3C would be similar to that of Fe. Andes calculates for the entropy of Fe3 C,S298 = 23.55 e.u. The heat of formation of Fe3C has been studied by several workers. Kelley3 has reviewed these measurements and calculations, and selects those of Roth* and Naeser6 as worthy of most consideration. Roth has given AH = 5400 cal. + 30 per cent as a result of his own and other work. Naeser has determined the heat of formation from Fe and different forms of carbon, and for graphite (0) he finds AH = 5600 cal. Kelley accepts the rounded figure AH = 5500 as the heat of formation at 298.1" K., but this value is quite uncertain.

Jan 1, 1940

By Mathias Jern, Ruilin Yang

A blast vibration model has been developed that simulates effects of almost all blast design parameters on the blast vibration peak particle velocity (PPV) from a production blast with multiple blastholes at a given point of interest in the rock. The velocity of detonation (VoD), initiation points, explosive types (density, VoD, energy), charge decoupling, and decking in each blasthole are simulated along with other blast design parameters. The information from signature hole blast vibration and the blast design are the input to the model. The model can be used to assess blast damage in proximity of blastholes as well as far field vibration PPV.

Jan 1, 2019

By John G. Hall

The pumping operations at the Chief mine have been unique in the respect that for many years the entire flow of water into the mine has been disposed of by pumping into natural underground "caverns" or "sinks." Volumes up to 4000 gpm have been pumped into these caverns with no apparent tendency for the caverns to fill with water, and it has never been proven that any of the water returns to the mine workings. Major pumping operations have been carried on during two periods, the first from 1918 to 1927, and the second from 1942 to the present time. Early Pumping Operations CHIEF MINE The Chief Consolidated Mining Co. was organized in 1909, and for the following nine years ore was developed and mined from the 600 level down to the 1800 level, all above the permanent water table, the 1820 level. The ore occurs as extremely-irregular pipes of replacement ore in limestone, and to date a total of approximately 2 1/2 million tons of ore has been produced. The ore was highly oxidized down to the permanent water level, and some highly-oxidized ore runs occur beneath the permanent water table. In 1916, with extensive mining being done on the 1800 level, 20 ft above the water table, there were indications that a zone of secondary enrichment might exist below the water, and in order to follow the ore runs to greater depth, it was realized that arrangements would have to be Made to pump water to the surface. The original pumping installation was designed to pump 350 gpm in five stages against a 1900-ft head to the surface. By January 1919, the water had been lowered to the 1900 level and an excellent grade of silver-lead ore was being produced from the zone of secondary enrichment. At this point. the flow of water equalled the capacity of the pumps, and pumps of an additional 1000 gpln were installed to supplement the original system. By January 1920, the water had been lowered approximately 100 ft, and the total flow of water was 1000 gpm. The water was being pumped from many different places in the mine where ore was being followed downward, with 27 different pumps operating below the 1800 level, mainly Cameron air-driven sinker pumps. These first sinking pumps were cumbersome and inefficient, and each of the larger pumps weighed approximately three tons and required tremeridous volumes of compressed air. During this period, an exploration drift being extended north and west from the Chief shaft on the 1600 level encountered a large natural cavern some 2000 ft from the shaft. This cavern in places measured 60 ft in diameter. Sometime later the disposing of water into this cavern was suggested, and as an experiment to determine the results of such an operation, an attempt was Made to fill the cavern by pumping in a small volume of water, but the water disappeared as fast as it was discharged into the cavern. It was decided then to try the cavern as a drainage outlet for the entire volume of water being pumped to the surface, and the water apparently did not return to the mine workings. Subsequently water up to 3000 gpm was pumped into this cavern. An attempt was made to determine whether any water was being returned from the cavern to the lower workings, and 100 lb of sodium fluorescein salt was added to the water discharged into the cavern, but no trace of it was found in the drainage water in the mine. Results of another such test will be described later.

Jan 1, 1950

By Gorrell. H. A.

Subsurface water data can be very valuable in .petroleum exploration and research. For the discussion of problems related to subsurface waters uniform nomenclature and classifications are required. The term 'connate water' has frequently been incorrectly used. It should .only be used in its original sense in which it is analagous to 'fossil water'. Classifications .based on origin and on sodium-chloride content are proposed. Present and possible uses of formation water analyses are briefly discussed. Since the potential uses of formation water data are not fully understood, complete analyses of selected samples should be made to insure against future requirements. The subsurface waters of Alberta show considerable regional variation in amount and proportion of dissolved salts.

Jan 1, 1958

By D. E. Norquist, J. E. Moeller

The results of wear on marked balls, 4, 31/2, 3, and 2 in. diam are given. All balls were forged steel of practically the same chemical analysis and hardness. The results indicate that balls in a given mill for a given length of time will have equal diameter losses, regardless of size.

Jan 1, 1950

By R. J. Mitchell

"A lest apparatus has been developed for obtaining the relations among confining stress, porosity and percolation rate for hydraulic sand backfills. The apparatus can also be used to evaluate internal drainage characteristics and the effects of partial saturation on percolation rates. The test apparatus, test procedures and typical test data are presented in this paper.IntroductionAlthough the standard percolation test has become an accepted method of evaluating the drainage characteristics of hydraulically placed tailings backfill, it is recognized that the test results require considerable interpretation due to the following factors: (I) The results can be markedly influenced by varying sample preparation procedures, which vary the amount of material segregation in the sample . In particular, a thin layer of slimes on the top of a sample can control the flow of water into the sample. Wall edge effects can also affect the test results. (2) The in-place porosity of the backfill is not duplicated in the test sample and empirical formulae must be used to estimate the variation of percolation rate with porosity. (3) Internal drainage characteristics and the percolation rate of partly saturated fill cannot be evaluated in the standard percolation test.In addition to eliminating these problems, the compression percolation test apparatus also provides additional data on the mechanical properties of the backfill. Compressibility (or bulk modulus) is measured at different stress levels during the course of a test and this information can be used in evaluating the usefulness of the fill in providing ground control and in limiting ground subsidence. The engineering design of mine backfill is becoming an important part of the over all design of underground mine operations. The design problems are sufficently different from conventional civil engineering soil mechanics problems that new test methods and design procedures are required."

Jan 1, 1981

By Paul C. Jones

Summitville is an old mining district located south of Wolf Creek Pass in the southern San Juan Mountains of Colorado at an elevation higher than 3500 m (11,500 ft). The Summitville mine site is about 40 km (25 miles) southwest of Del Norte. The current mine, developed by Galactic Resources Ltd. and its subsidiaries in the mid-1980s, is on the north facing side of South Mountain. The area is drained by Cropsy Creek to the east and Wightman Fork to the north, both tributaries to the Alamosa River. Mining in the Summitville area began in 1870 when James Wightman discovered placer gold on what is now known as Wightman Fork of the Alamosa River. The first vein-type deposits were located in 1873 on South Mountain near the current Summitville Mine. Mining began in the district in 1875 and continued sporadically through 1942. Major mining episodes occurred from 1875 to 1894 and from 1926 to 1942. Total gold production from the mining district through 1949 totaled 7.5 t (240,000 oz). An additional 7.7 t (249,000 oz) were produced during Galactic's tenure. Natural degradation of the outcropping sulfide-rich veins in the area and the early mining activity, including development of the Reynolds, Dexter and Iowa drainage tunnels in the late 1890s, have polluted the streams draining the area with heavy metals and acidic water. Names of the various tributaries to Wightman Fork, such as Iron, Alum and Bitter Creek, testify to this natural pollution. This degradation has reduced, or killed, aquatic life in several area creeks, including Wightman Fork, for many years before recent mining activity.

Jan 1, 1993

I HAVE to thank the members of the Institute most cordially for the honour conferred upon me in selecting me President, which position my poor services have prevented my filling adequately. I have, therefore only been able to stumble through my year of office under the guiding direction of our esteemed Secretary. I fully appreciate the honour done to me; and, now that it is over, I can look back with pride and pleasure at having occupied the chair; but I am told that it remains for me to fill one of the requirements of our Institute and present you with what has been dignified by the name of a presidential address. My relief in complying with this is in the knowledge of its freedom from the usual discussion which appertains to papers presented by our worthy members. It has been usual in the past for the subject chosen to be specially connected with the work immediately engaging the attention of your president, and on this occasion I would like to break away from this time-honoured custom and engage your attention for a brief space on what is equally dear to us all namely, Ideals of the Profession. In doing so, the retort of Whistler to an art student gives me, I must admit, much misgiving, for, on being asked how he developed his artistic talents, replied that he painted what he saw, which produced the immediate reply, "Ah, but the tragedy will come when you see what...

Jan 1, 1909

By Leandro Nakamura Alves Vieira

O acirramento da competição no mercado de aço tem exigido esforços de inovação e redução de custos. Por sua vez, as técnicas agrupadas como ICME - Integrated Computational Materials Engineering vêm acelerando o desenvolvimento e a otimização de materiais e processos de fabricação. O emprego destas técnicas tem sido uma ferramenta extra para assegurar a competitividade na indústria. Neste trabalho o uso da termodinâmica computacional no desenvolvimento e processamento de aços elétricos é revisado através da discussão de exemplos. Cálculos de equilíbrios mais relevantes para o processo de fabricação destes aços (tanto de grão não orientado-GNO como orientado-GO) permitem obter informações sobre as transformações de fases, solubilização de precipitados (sulfetos e nitretos) essenciais para a obtenção de texturas cristalográficas ideais. Os cálculos são discutidos e comparados com resultados reais. Discutem-se ainda, cálculos no sistema aço-gás, e os efeitos da composição da atmosfera na formação de óxidos na superfície do aço. Tais cálculos são importantes para descrever previamente as transformações que ocorrem durante as várias etapas de fabricação, assim como os efeitos dos parâmetros de processo sob os aços elétricos. A aplicação da técnica permite otimizar o processamento e o desenvolvimento dos aços elétricos em diversos aspectos. As vantagens e limitações do método, assim como o potencial de outras técnicas de ICME, na área, são discutidas.

Aug 7, 2018

By Nicola Baldo, Marco Pasetto

"The paper presents the results of a laboratory study, conducted at the Experimental Road Laboratory of the University of Padova, in order to verify the possibility to use different types of electric arc furnace (EAF) steel slags – in substitution of the natural aggregates – in the composition of both dense graded and porous asphalt mixes for flexible road pavements. The research has been articulated in a preliminary study of the chemical, physical, and mechanical properties of the EAF steel slags, and in the following mix design and performance characterization of the bituminous concretes, through stiffness modulus tests at various temperatures and permanent deformation (creep) tests. All the mixtures with EAF slags have satisfied the requisites for acceptance standardized for the road sector, thus resulting as suitable for use in the construction of infrastructures, moreover presenting higher mechanical characteristics than those of the corresponding asphalts with full natural aggregate. IntroductionSteel is produced industrially employing two main technologies: the integral cycle, which starts from mineral iron, and the electric cycle, which uses scrap metal. A consistent amount of the steel produced in Italy (approx. 55%) comes from Electric Arc Furnaces (EAF), which every year, alongside the steel, produce approximately 2 million tons of slag. The recycling of this waste product to produce new high-quality raw materials would reduce both the exploitation of limited natural resources and the amounts of refuse. In the European Union, 60% of slag from EAF is still today disposed of in dumps. The extremely diverse origins of scrap metal (waste from mechanical manufacturing, industrial and civil demolition, car bodywork, etc.) means that the by-products generated by the smelting, slags and ashes, contain different elements, in varying composition, also depending on the type of steel to be produced and the consequent adding of binding and melting elements during the production process. For this reason, iron and steel industry electric furnace slag - unlike the blast furnace dross utilised in cement works, which has a more uniform composition as it comes from a more standardised cycle – has been viewed in the past with some diffidence and so, at least in Italy, the possibilities of its re-use have never been fully developed."

Jan 1, 2008

By Vishal Shukla, Ashok Kumar, Manas Ranjan, D. Chakraborty, Narayan Sharma

Jigging has a very important role in mineral processing Industry. Upgrading of Iron Ore by jigging has been an emerging trend. A detailed investigation is carried out to understand the influence of Jig feed granulometry and bed height during jigging operation. Noamundi jig plant data shows that variation in jig feed granulometry, feed quality and bed height are major contributors to fluctuation in jigging performance. At Noamundi the feed size (-10.0+0.5mm) fraction is used for fines jigging operation. To understand the effect of granulometrey on jig plant performance such as yield, separation efficiency and Fe recovery. In this context The performance of jigging was evaluated by daily average data from jig operation was used to study the influence of feed distribution on jigging performance .Coarser fraction (+6mm) has a positive influence , whereas fines fraction (-0.5mm) tends to lower performance . During Jigging rearrangements of Particles takes place due to an alternate expansion and compaction of Jig Bed .These particles are arranged by increasing density from top to bottom. During the particle stratification, Jig bed physically cut at desired horizontal particle density plant to separate the desired product. Investigation shows that optimum bed height is required at different Jig feed quality to achieve desired product quality, maximum separation efficiency and Fe recovery. This Paper will illustrate role of granulometry and Bed height control on Jigging plant performance.

Jan 1, 2014

By F. J. Reichhardt

Abstract -The Molopo Farms Complex is a major, layered ultramafic/mafic, early Proterozoic intrusion which is totally covered by sediments of the Karoo and Kalahari Formations and situated in southern Botswana and northeastern South Africa. The approximately 3000 m thick, generally fine- to medium-grained ultramafic and mafic cumulates are intrusive into equivalents of Transvaal Supergroup sediments and lavas. Multiphase deformation resulted in tilting and segmentation of the Complex into individual tectonic blocks. Sr isotopes document at least two chemically distinct parental liquids which interacted in a complex manner to form an approximately 1000 m thick rhythmically layered succession which straddles the ultramafic/mafic boundary. Repeated mixing resulted in a complex cryptic layering pattern and numerous sulfide-enriched layers which contain significant PGE +Au concentrations.

Jan 1, 1994

By A Reschke

The Thiess John Holland Group is undertaking the design and construction of Brisbane’s Airport Link Project, the largest single investment in transportation infrastructure in Australian history. Twin Herrenknecht TBMs are being used to bore parallel road tunnels from Kalinga Part in Toombul through to Lutwyche, a distance of 2.45 km. At 12.48 m, these tunnel boring machines (TBM) are the largest diameter machines, outside of Japan, to incorporate annular two-component type grouting through the tailskins.Grout design, preparation and injection have been given particular attention in this project in order to push the boundaries of achievement. Laboratory testing was conducted on various mix designs to ensure the contract specifi cations for grout strength could be met. To study the mechanics of the grout injection process, Herrenknecht supplied a test rig which duplicates the grout injection systems on the TBMs. Multiple recipes were tested, carefully selected to balance the requirements of rapid strength development with high mobility (to completely fill the void between the segmental lining and the ground) and minimal bleed.Team Mixing Technologies, Canada, was selected as the grout plant provider based on the technical performance of their high shear colloidal mill mixers. Field results have shown that the colloidal mixer prepared grout gives almost double the strength of an identical grout prepared by a paddle mixer.

Mar 8, 2011

By Edwin T. Myskowski, Alfred H. Hesse

THE development by the U. S. Bureau of Mines of a process for purifying manganese by electrolysis has stimulated interest in manganese alloys. While recent publications have shown some alloys of manganese and copper to possess rather unusual properties, none have included information on tensile properties, which have an important bearing on the usefulness of the alloys. Manganese-copper alloys can be heat-treated, since the single phases that exist at high temperatures may be retained by quenching. According to Persson,1 when quenched alloys containing from about 30 to nearly 100 per cent manganese are reheated, alpha manganese is precipitated (Fig. I). Calculations based on Persson's X-ray data indicate that this decomposition is accompanied by a change in volume of as much as 5 per cent. The reason that this large volume change has not been noted probably is the slow rate at which equilibrium is reached by these alloys. In an investigation on hardening by cold-work and heat-treatment, Dean and Anderson' found that quenched alloys increase in hardness with manganese content and that high-manganese alloys harden very slowly with cold-work, while high-copper alloys harden much more rapidly. Heat-treatment has little effect on manganese-copper alloys containing less than 40 per cent Mn, and affects those alloys containing more than 40 per cent in accordance with their manganese content and heat-treating temperature. Dean and Anderson4 also found that cold-work increased electrical resistance of alloys containing from 50 to 80 per cent Mn, and that heat-treatment of alloys containing from 40 to 96 per cent Mn altered the electrical resistance considerably. Dean, Anderson and Potter5 have shown that the high vibration damping capacity that characterizes manganese-copper alloys containing 40 to 90 per cent Mn is affected by cold-work and heat-treatments. Highest vibration damping capacity at low stresses was obtained by heating for 2 hr. at 450°C. (842°F.) after quenching from solution temperatures. Preparation of Alloys.-The alloys for these tests were melted in a 17-lb. basic-lined high-frequency induction furnace using electrolytic manganese, grade A ingot copper and a 70-30 Cu-Mn master alloy (69.80 per cent Cu, 0.12 Fe, 0.04 Si, 0.006 S, 0.07 C, balance Mn). The manganese was heated slowly to expel excess dissolved gases and melted before the addition of copper. No fluxes or covers were used. The melts were cast in tapered iron molds and the ingots were reduced 90 per cent when forged to ½ -in. rounds. These rods were given 2-hr. solution treatments at temperatures that depended upon the composition (Table I). Tensile Tests.-The tensile specimens, 0.313-in. diameter (1.25-in. gauge length), which were enclosed in evacuated Pyrex

Jan 1, 1942

By Yuhua Wang, Huilan Yang, Yanqing Jiang, Dongfang Lu

"Generally, the concentration of bauxite flotation tailings is around 10%, a large amount of water in tailings needed to be recycled in the flotation process. Sedimentation and dewatering properties of tailings were investigated under different conditions. Surface high negative charges on mineral particles are the key factor to destroy the settlement of tailings when the pulp pH is around 8.9. Hence, the modification of pulp pH around 7 is necessary to the diminution of the repulsive force between mineral particles and then the acceleration of sedimentation of tailings. Anionic polyacrylamine with molecular weight of 14 million is the best flocculant for the settlement of tailings in all tested polyacrylamines. P-toluene sulfonic acid shows better properties than hydrochloric acid for pulp pH adjustment when anionic polyacrylamine with molecular weight of 14 million is used as flocculant. Although the flotation of diaspore is depressed in the presence of polyacrylamine using sodium oleate as collector, but the recycling water traded by the combination of ployacrylamine and p-touenesulfonic acid does not show the depression effects on the flotation of bauxite ore. The lower residual content of polyacrylamine in recycling water treated by the combination of ployacrylamine and p-touene sulfonic acid plays an important role. INTRODUCTION Generally, the waste water generated from mineral processing plant is usually treated by sedimentation, oxidization, electrodialysis, ions exchange, active carbon adsorption and flotation technology, and the treated water is also used again in the industrial process. Flotation was adopted widely to improve the quality of bauxite from low grade diasporic bauxite in China. For flotation, the grinding fineness of bauxite is over 90% -0.074 mm, sodium carbonate and sodium hexametaphosphate were used as regulators, so the tailings pulp is very difficult to settle and be dewatered (Y. Wang et al., 2004; Y. H. Wang et al., 2007; Wang Yu-hua et al., 2008; Wang Yuhua et al., 2011). The water recycling of bauxite tailings are becoming the highlight for the industrial application of the flotation process for bauxite ore. Researchers in China shift their attentions onto this topic."

Jan 1, 2018