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By George S. Evans

CERTAIN American operators believe that desulphurizing in the ladle offers a means of increasing blast-furnace and open-hearth yields with the possibility of improvements in quality of the steel. In fact, several producers have experimented with practically all of the known desulphurizing agents, including both standard grades of the alkalies and special preparations that have been offered from time to time during the past several years. Some of these are regularly being used today in large-scale commercial operations, with good results. Also, it is the practice to treat off-sulphur casts in the blast-furnace ladle at a number of plants. It is not known, however, that anyone in the steel industry (American) has ever adequately equipped a plant for desulphurizing blast-furnace metal in an efficient manner as regular operating practice. The purpose of this paper is to illustrate the importance of correct equipment and proper handling for obtaining uniform and efficient results. As will be shown, at the temperature of molten iron the alkalies are instantly neutralized by any free slag present, dissipating their desulphurizing value. Entrained silicates are rapidly washed out of the metal bath by the highly basic soda slags and will be satisfied ahead of desulphurizing reactions with FeS. More or less of the reagent will always be used up through reactions with the refractory lining. Desulphurization will be limited to the action of the free alkali then remaining in the slag. Causes for the erratic results generally found with desulphurizing tests in blast-furnace transfer ladles would include, among other things, variations in the quantity of furnace slag coming down with the metal, and differences in the percentage of kish and entrained silicates in the different casts. As the alkalies instantly unite with any free slags or silicates present, these, with any kish coming off, both dilute the reagent and reduce the surface contact between the slag and metal, thereby retarding the desulphurizing reactions.

Jan 1, 1938

By George S. Evans

Certain American operators bclieve that desulphurizing in the ladle offers a means of increasing blast-furnace and open-hearth yields with the possibility of improvements in quality of the steel. In fact, several producers have experimented with practically all of the known desulphurizing agents, including both standard grades of the alkalies and special preparations that have been offered from time to time during the past several years. Some of these are regularly being used today in large-scale commercial operations, with good results. Also, it is the practice to treat off-sulphur casts in the blast-furnace ladle at a number of plants. It is not known, however, that anyone in the steel industry (American) has ever adequately equipped a plant for desulphurizing blast-furnace metal in an efficient manner as regular operating practice. The purpose of this paper is to illustrate the importance of correct equipment and proper handling for obtaining uniform and efficient results. As will be shown, at the temperature of molten iron the alkalies are instantly neutralized by any free slag present, dissipating their desulphurizing value. Entrained silicates are rapidly washed out of the metal bath by the highly basic soda slags and will be satisfied ahead of desulphurizing reactions with FeS. More or less of the reagent will always be used up through reactions with the refractory lining. Desulphuriza-tion will be limited to the action of the free alkali then remaining in the slag. Causes for the erratic results generally found with desulphurizing tests in blast-furnace transfer ladles would include, among other things, variations in the quantity of furnace slag coming down with the metal, and differences in the percentage of kish and entrained silicates in the different casts. As the alkalies instantly unite with any free slags or silicates present, these, with any kish coming off, both dilute the reagent and reduce the surface contact between the slag and metal, thereby retarding the desulphurizing reactions.

Jan 1, 1938

By George S. Evans

Certain American operators bclieve that desulphurizing in the ladle offers a means of increasing blast-furnace and open-hearth yields with the possibility of improvements in quality of the steel. In fact, several producers have experimented with practically all of the known desulphurizing agents, including both standard grades of the alkalies and special preparations that have been offered from time to time during the past several years. Some of these are regularly being used today in large-scale commercial operations, with good results. Also, it is the practice to treat off-sulphur casts in the blast-furnace ladle at a number of plants. It is not known, however, that anyone in the steel industry (American) has ever adequately equipped a plant for desulphurizing blast-furnace metal in an efficient manner as regular operating practice. The purpose of this paper is to illustrate the importance of correct equipment and proper handling for obtaining uniform and efficient results. As will be shown, at the temperature of molten iron the alkalies are instantly neutralized by any free slag present, dissipating their desulphurizing value. Entrained silicates are rapidly washed out of the metal bath by the highly basic soda slags and will be satisfied ahead of desulphurizing reactions with FeS. More or less of the reagent will always be used up through reactions with the refractory lining. Desulphuriza-tion will be limited to the action of the free alkali then remaining in the slag. Causes for the erratic results generally found with desulphurizing tests in blast-furnace transfer ladles would include, among other things, variations in the quantity of furnace slag coming down with the metal, and differences in the percentage of kish and entrained silicates in the different casts. As the alkalies instantly unite with any free slags or silicates present, these, with any kish coming off, both dilute the reagent and reduce the surface contact between the slag and metal, thereby retarding the desulphurizing reactions.

Jan 1, 1938

By Anne Kvithyld

Silicon solar cells, that convert the energy of sunlight into electric energy, are attractive sources of energy. In the production line wafers of solar cells are sliced from a multicrystaline ingot solidified unidirectionally. Recycling scrap from top and sides of such ingots is addressed. SiC and Si3N4 inclusions are a major problem. Scrap from Scan Wafer ASA is melted in a high vacuum furnace at around 1500ºC. The filters, from commercial producers, are C and SiC with 10, 20 and 30 ppi. Characterisation of inclusions before and after filtration, and in the filter itself, is performed by microscopy. Dissolution of silicon in acid and counting of the un-dissolved inclusions is also carried out. In the filter Si3N4 needles and SiC inclusions were identified. The amount of these inclusions in the filtered silicon is much less than in the input. In conclusion, filtration using SiC and C filters in vacuum system in argon atmosphere removes SiC and Si3N4 inclusions from solar cell scrap. Flow of metal through the filters is not a problem. These results are promising with scale-up to industrial application in mind.

Jan 1, 2006

By ALFRED D. FLINN

ENGINEERING COUNCIL has passed, not out, but upward! Therefore, its recent wake was conducted by itself as a joyful occasion somewhat in advance of its official demise. Council held its last meeting in Washington, Dec. 16, 1920. Business was transacted with dignified gravity in the forenoon. During the afternoon calls were made upon the chiefs of technical bureaus of the Government: the Chief of Engineers, U. S. Army; Chief of Yards and Docks of the Navy Department; Director of U. S. Reclamation Service; Director of U. S. Geological Survey; Director of Bureau of Mines. The Council pronounced them, each and all, able men and true. But what of the evening? Well, there was a dinner at the Washington Hotel. Twenty-six men gathered around a flower-strewn table-not a casket. As guests, there graced the festive board the hosts of the afternoon calls, and a number of members of the new American Engineering Council. The body about to be apotheosized-otherwise known as Engineering Council-was both jocular and reminiscent. Rewards were bestowed and appreciations expressed. To the man who had for three long years borne the burden of chairmanship and whose financial recklessness made possible the Washington office and the movement for a National Public Works Department, the following "note," duly engrossed and signed, was given, accompanied by "The Song of the Council Crew."

Jan 1, 1921

By Felix Degold, Mark Ganster

Achieving a customer optimized fragmentation by using robust data from new technologies e.g. GPS positions of boreholes, fragmentation analysis to calibrate the geology and fragmentation prediction models. The inclusion of the collected data into the blast’s design makes it possible to accomplish a desired particle size distribution.

Feb 1, 2020

By Huanyu Zhang, Quanqiang Ma, Huiqing Tang

Improvement of the coke quality for blast furnace (BF) iron making by hydrothermal oxidation treatment on coke quality was investigated. Results show that, under subcritical condition, sulfur removal rate is 15% and the weight loss is 3%; under supercritical condition, both sulfur removal rate and mass loss rate increase with the increase of H2O2 concentration. In the experimental conditions, sulfur removal rate and mass loss rates were 45% and 17%, respectively. Hydrothermal oxidation treatment could reduce the CO2 reactivity of the coke and the treatment under supercritical condition is more effective. Hydrothermal oxidation treatment could improve the graphitization of the coke and smoothness of pore boundary in the coke and the treatment under supercritical condition is more effective.

Jan 1, 2016

By G. Deschênes

Located in North West Tanzania, Buzwagi is an underground narrow-vein gold mine owned by Barrick Gold. The plant was commissioned in 2000. The reserves are estimated to be more than 25 years. The ore, containing gold, silver and copper mineralization in sulphides, is processed at 3,300 tpd. This paper presents the results of an investigation to determine the performance of an ammonia-cyanide leaching approach to recover gold from two samples. Coarse gold was recovered by gravity prior to leaching. The gravity tailings had the following composition; 1.97 g/t Au and 0.31% copper for the medium cyanide soluble copper (MCSC) sample and 2.80 g/t Au and 0.53% Cu for the high cyanide soluble copper (HCSC) sample. Experiments were conducted for 72 hours in stirred tank reactors with monitoring and control of parameters. The straight cyanidation produced gold extractions of 76.1% for the MCSC sample and 84.6% for the HCSC sample. Associated cyanide additions were 6.1 kg/t and 11.5 kg/t respectively. The gold extraction of the MCSC sample was improved to 88.8% using 350 ppm NaCN and 700 ppm ammonia. The associated cyanide and ammonia additions were 2.5 kg/t and 1.7 kg/t respectively. For the HCSC sample, 82.5% gold extraction was obtained using 500 ppm NaCN and 600 ppm ammonia. The cyanide addition and ammonia additions were reduced to 3.8 kg/t and 1.0 kg/t respectively. No significant decrease in gold extraction was noticed when the cyanide and ammonia were reduced to 150 ppm and 500 ppm respectively. In the presence of ammonia, a significant amount of cyanide was oxidized to cyanate by the cupric ion. In the absence of ammonia, the formation of copper cyanide was the predominant reaction responsible for consumption of cyanide.

Jan 1, 2012

By F. B. Petermann

Two-stage electric smelting tests, using small submerged arc furnaces, were made on high-iron manganiferous materials from the Pioche District, Nev., and the Cuyuna Range, Minn. The object was to reduce sufficient iron in the first stage to give a slag with a favorable Mn to Fe ratio for smelting to ferromanganese in the second stage. The nodulized flotation concentrate from the Pioche District contained 29.2 percent Mn and had a Mn to Fe ratio of 2.3:l. When smelted with coke and silica or alumina as flux, more than 90 percent of the manganese was recovered in slags with Mn to Fe ratios of 10: :24:1. The Pioche slag was smelted to ferromanganese using coke and lime- stone or dolomite as flux. The ferromanganese was high in silicon but other- wise met specifications. Recovery of manganese to ferromanganese in this step was 73 to 78 percent. Overall recovery of manganese was about 70 percent. The sintered flotation concentrate from the Cuyuna Range material contained 12.9 percent Mn and had a Mn to Fe ratio of 0.3:1. When smelted with limestone as flux, about 83 percent of the manganese was recovered in a slag with a Mn to Fe ratio of about 6:1. The Cuyuna slag was smelted to ferromanganese with coke and limestone for flux. Recovery in this step was 61 percent of the manganese in a high silicon ferromanganese. Overall recovery of manganese was about 50 percent.

Jan 1, 1963

By K. Ohga

Japan has produced 14-16 million tons of coal per year in the past several years. About half of the production comes from eight coal mines in the Ishikari coal field, Hokkaido. Most of the gassy coal mines are in this field and the average mining depth of these coal mines has already attained about 700 m from the surface. Therefore, most of the coal mines have suffered from occurrences of coal and gas outbursts. To prevent outbursts and to reduce ventilation air, gas drainage has been carried out at all of these coal mines and these have had successful results. However, the methods of gas drainage differ from mine to mine. In this report, an outline of the main methods of gas drainage are described.

Jan 1, 1987

By AIME AIME

CHARACTERIZING the annual meeting as the biggest and best one yet has happened so repeatedly that some may suspect it has become a conventional phrase, like "good morning," and yet, what else can be said when not only one but all the many who express an, opinion use exactly those words, while the first of the two adjectives refers to a physical fact that is established by count. Perhaps there were hose who thought it not the best, but if so they were too tactful to say it out loud. So without further ado . let us admit that the one hundred and thirty-ninth general meeting of the A. I. M. E. held; as our By-laws provide, in New York during the third week of February, was the biggest and best of them all. Perhaps it is because we appreciate friendliness more as we grow older, but somehow the friendly atmosphere seems to rise slowly in temperature with the passing of the years. The actual atmosphere on the opening morning was quite the contrary, Feb. 17 being the coldest clay, so far, of this winter, and the suburbanites claimed that their thermometers had registered 5" below zero when they got up, though the official records of the weather man did not go that low. From that time the temperature steadily rose until Thursday afternoon, when the official record of 66" constituted a record high for Feb. 20 at New York. The weather man explained it by learned discussion of highs and lows, but we suspect the A.I. M. E. members must have had something to do with it.

Jan 1, 1930

Howland Bancroft (A Modern Approach To Foreign Mineral Development, P 666) was born in Denver, Colo and attended the University of Colorado, University of Michigan and received a B S and B A degree From 1907 to 1912 he was with U S Geological Survey In 1911 he was involved in study of mining resources of Peru Mr Bancroft resigned from Federal Survey and opened offices as consulting mining geologist in Denver in 1912 From 1919 to 1920 he was a consulting engineer in San Francisco He was manager of Sinclair Panama Oil Corp in Panama City in 1920 From 1921 to 1923 he was vice president and managing director of same corporation He did independent examinations in Western states and an exploration trip through Turkey in Asia from 1924 to 1925 Mr Bancroft was vice president and general manager of Lago Petroleum Corp in charge of operations in Venezuela Mr Bancroft has spent time in 34 different countries in the world and in a number of different Latin American States, Europe, Asia Minor and Africa

Jan 1, 1952

By G. W. Cutting

It is well known in both the research field and in commercial flotation processes that the grades and recoveries obtained from flotation plants are heavily influenced by the structure and height of the froths produced in the flotation cells. The development of steady-state mathematical models of flotation processes based upon practical and readily obtained parameters have demanded detailed information about the structure of flotation froths. The important parameters are the distribution of floating values, gangue and water in the froth with respect to froth height, cell pulp density, cell air flow rates and flotation inducing additives. Little work has been conducted in this field although considerable attention has been paid to bubble loading and other factors close to the cell froth/pulp interface. Laboratory batch tests are prefaced for the derivation of the above mentioned parameters for both practical and economic reasons. The standard laboratory flotation tests using a batch cell produces a froth of low height (1 to 3 cms generally) together with a varying cell pulp density as the test progresses due to the addition of top up water and the removal of froth from the cell. This form of test can be considered only as giving information about froth conditions close to the cell froth/pulp interface under conditions of widely varying cell pulp densities. In commercial processes the froth heights are much larger (frequently greater than 10 cms); therefore the laboratory batch test, although useful in many ways, does not directly yield parameters relating the state of the froth flowing over the cell lip to process operating conditions. To investigate flotation conditions, where more realistic froth heights are developed, an equilibrium type of batch cell has been developed at Warren Spring 1 Laboratory . In this a tank with high walls is used to contain the pulp and whole froth and, after a short period of operation, an equilibrium between froth

Jan 1, 1975

By María del Rosario González Moradas

El presente texto señala las diversas metodologías adoptadas para la evaluación del impacto visual de la industria extractiva en Asturias (Norte de España) mediante el empleo de las herramientas SIG. Para ello, se evaluaron individualmente el impacto visual de tres canteras de diferente tamaño y morfología, de forma que se obtuvieron las longitudes y superficies aparentemente visibles desde cualquier punto. Así también se analizó la competencia de utilizar el campo visual ocupado por la cantera, el cual se ha calculado a partir del ángulo sólido. Finalmente, se muestran los resultados de las 98 explotaciones a cielo abierto ubicadas en la región y que son adquiridos a partir del modelo digital de elevaciones de resolución 5 m y de los contornos de las zonas explotadas.

Feb 1, 2015

By Bora Derin

The partial pressure ratios of sulfur and oxygen for several copper flash smelting plants were derived using the Reddy-Blander (RB) model and predicted dissolved sulfur contents available in the literature. The sulfide capacities (Cs) of six different flash smelting plants (FeO-CuOo.5- CaO-MgO-FeOu-AlO15-SiO2) slags were calculated. The log (PO2/PS2) versus matte grades of various industrial processes was determined. The PO2/PS2 ratio increased with an increase of copper grade. The calculated partial pressure ratios for the copper flash smelting are in good agreement with those of the experimental data.

Jan 1, 2003

By L B. Zhou, S Li, B L. Wang, S B. Li, Q Wang

The rapid development in ChinaÆs metal mine resources has caused a series of mine environment problems such as serious ecological damage and environment pollution, and secondary geological disasters. The paper has reviewed ChinaÆs metal mine development, including current status and environmental situation, analysed existing problems in mine development and environmental management, and proposed corresponding countermeasures and suggestions.CITATION:Wang, B L, Li, S B, Li, S, Zhou, L B and Wang, Q, 2012. Current situations, problems, countermeasures and suggestions for ChinaÆs metal mine development, in Proceedings Life-of-Mine 2012 , pp 353-356 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 10, 2012

By James P. Bennett

EAF slag chemistry and its control have been recognized as important in producing quality steel at a low price for a number of decades_ EAF steel producers make lime and dolomite additions to furnaces, controlling the CIS ratios and sulfur pickup from the steel. Existing phase diagram data at 1600°C for CaO, MgO, FeO, SiO2, and Al2O3 was used to write a computer model optimizing slag chemistry for slag foaming and reduced refractory wear. The model, its development, and its use in an industrial steelmaking environment will be discussed along with how the model can improve energy efficiency. The importance of EAF mass balance to account for critical materials like Si in scrap and refractory wear using the model will also be emphasized_

Jan 1, 2003

By Renato Luciano de Araújo Menezes

O objetivo do presente trabalho é evidenciar os resultados do incremento de superfície específica obtidos pelo roller press da Usina 3 da Samarco Mineração S.A.. A metodologia utilizada baseou-se em informações de projeto do equipamento e análises estatísticas aplicadas ao processo de prensagem bem como o desenvolvimento de um indicador de eficiência imune às variações de qualidade do minério. Basicamente esse trabalho buscou otimizar as variáveis de processo capazes de gerar melhores resultados de incremento na superfície específica do minério. (Como resultado do trabalho foi verificado um aumento considerável nos resultados de eficiência no incremento de superfície específica).

Aug 16, 2017

By G. R. Leverant, M. Gell

The high- and low-cycle fatigue poperties of MAR-M200 directionally -solidified into columnar-grained and single crystal forms were determined at 1400" and 1700°F. These results were compared with the corresponding properties of conventionally -cast MAR-M200. The low-cycle fatigue lives of the columnar-grained and single crystal materials were similar at both temperatures and were one to two orders of magnitude greater than those of conventionally-cast material. The variations in the fatigue lives among the three forms of MAR-M200 were related to the more rapid rate of intergranular muck propagation compared to that of transgranular propagation. In conventionally-cast MAR-M200, cracks were initiated in grain boundaries and crack popagation occurred rapidly along an almost continuous grain boundary path. In the columnar-grained material, crack initiation occurred on short transverse segments of grain boundaries, but crack propagation was transgranular. The fatigue lives of columnar-grained and single crystal materials were approximately the same because most of the life in both materials was spent in trans-granular propagation. For the directionally -solidified materials, the number of cycles to failure, Nf, can be related to the total strain range, , by: heT = K where n and K are 0.16 and 0.044 at 1400'F and 0.29and 0.098 at 1700, respectively. In addition to intergranular crack initiation in the columnar-grained material, initiation also occurred at we-cracked MC carbides and micropores in both directionally-solidified materials. At 1400°F, fatigue life was reduced with increasing MC carbide size, but at 1700 there was no effect of carbide size. THE creep and stress-rupture properties of conventionally-cast nickel-base superalloys can be greatly improved by directional solidification into either single crystal or columnar-grained forms. The improvement in properties results from a reduction in intergranular cavitation and crack growth in the columnar-grained materials and the complete absence of this fracture mode in the single crystals. This paper describes the effect of grain boundaries on the elevated temperature fatigue properties of the nickel-base superalloy MAR-M200. The effect of cycling frequency on cracking arid fatigue life and the role of MC carbides and micropores on crack initiation are also emphasized. The fatigue properties of columnar-grained and single crystal MAR-M200 at room tem- perature,4,5 and the change in the mode of fatigue crack propagation with temperature6 have recently been described. I) EXPERIMENTAL PROCEDURE The material used in this study was the nickel-base superalloy MAR-M200, directionally-solidified into columnar-grained and single crystal forms. The columnar grains were approximately 0.5 mm in diam. The nominal composition of these materials in wt pct was 0.15C, 9Cr, 12.5W, loco, 5A1. 2Ti, lCb, 0.05Zr. 0.015B, bal Ni. They were solutionized for 1 to 4 hr at 2250°F followed by aging at 1600°F for 32 hr. which resulted in 0.2 pct offset yield stresses of 150,000? 144,000, and 95,000 psi at room temperature? 1400°, and 1700°F, respectively. The corresponding elastic moduli parallel to the testing direction were 19.2. 15.0, and 12.5 x 106 psi, respectively. Specimen design, testing procedures and alloy mi-crostructure have been described previously and will only be summarized here. Following the 1600°F aging treatment. MAR-M200 contains an ordered, cuboidal, y' precipitate 0.3 1 on edge, which is coherent with the 1 matrix. The y' precipitate is quite stable; even after testing at 1700°F. the precipitate is only slightly enlarged and its corners somewhat rounded. The alloy also contains a small volume fraction of micropores, and MC carbides. some of which contain preexisting cracks5 formed during casting. These cracks are always parallel to the long dimension of the carbide. Measurement of MC carbide size has been described previously.5 Axial fatigue tests were conducted in air over a wide range of strain amplitudes in both the high - and low-cycle fatigue regions, with specimen lives varying from about 10' to 10' cycles. Low-cycle fatigue (LCF) tests were strain-controlled with strain varied between zero and a maximum tensile value at a frequency of about 2 cpm. High-cycle fatigue (HCF) tests were stress-controlled with the stress varied between 5000 psi and a maximum tensile value less than the yield stress at a frequency of either 10 cps or 0.033 cps (2 cpm). The temperature in the gage section was controlled to 52°F. Specimen axes were within 5 deg of the [001] growth axis of the single crystals and the common [001 ] growth axis of the columnar-grained material. Specimen gage sections were electro polished prior to testing. After the standard heat treatment, three specimens were coated with a typical aluminide coating applied as a slurry. An additional specimen was given the coating heat treatment without actually being coated. In all cases: specimens were reaged at 1600°F for 32 hr after receiving the coating heat treatment at 1975'F for 4 hr.

Jan 1, 1970

By Alex Luyima, Honglan Shi, Lifeng Zhang, Yongqing Jiang

"Leaching process has been suggested to recover most metals from waste PWBs. In this study, the leaching behavior of most metals present in waste PWBs is evaluated before and thermal treatment. Different leaching acids: hydrochloric acid (HCl), nitric acid (HNO3) and aqua regia are compared. The effects of acid concentration, particle size of sample, leaching time and temperature are examined. Results revealed that most metals are present in small particle size and sequential leaching of PWBs with a combination of HCl acid and aqua regia is capable of dissolving most of the metals content of PWBs. Leaching of thermally treated PWBs produced the highest leaching percentages for similar leaching conditions.IntroductionApproximately 20–50 million tonnes of electronic waste (e-waste) is produced globally per year. Waste Electrical and Electronic Equipment (WEEE) or E-waste is one of the fastest growing waste streams in the world. In developed countries, it equals 1% of total solid waste on an average [1]. The growing stockpile of used and obsolete consumer electronics has been called the “largest toxic waste problem of the 21st century [2]. Printed wiring boards (PWBs) is an essential part of almost all WEEE, and accounts approximately 3% of all WEEE by weight [3]. PWBs are a platform upon which microelectronic components are mounted. PWBs contain metals (~40 wt. %), ceramics (~30 wt. %) and plastics (~30 wt. %) [4]. The metallic part includes; Cu, Pb, Zn, Fe, Cd, Be, Cr, Au, Pt, Pd, Ag, etc. The plastic part of the PWBs is mostly epoxy resins. These plastic resins also contain very toxic halogenated flame retardants (HFRs) [5]."

Jan 1, 2012