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By M. Misra

The interaction of xanthate with SO2 in the flotation of sphalerite and chalcopy.ite is discussed. 'The SO depression of sphaledte is due to the decomposition reaction of xanthate by SO2 The decomposition reaction is dependent on the cole ratios of xanthate/SO2, oxygen concentration and pH. Xanthate adsorbs at a faster rate by chalcopyrite than sphalerite. The faster rate of xanthate adsorption by chalcopyrite and the specific action of S02 on the surface of chalcopy.ite facilitate the selective separation of chalcopyrite from sphaledte.

Jan 1, 1989

By J. A. M. Cano

A brief introduction is made on the existence of sulphides in the top gas of the Midrex Shaft Furnace, giving consideration to the operation of the furnace and the liberation of sulphur as well as its consequential effects on the reduction process. The text shows a study of sulphur distribution in the pellet, emphasizing the importance of this distribution in relation to the liberation of sulphur during the reduction. A study was made to determine the sulphur compounds that exist in the pellets, showing ways of controlling the sulphur distribution and reducing its liberation?during the reduction.

Jan 1, 1989

CHAIRMAN DOUGHTON of the House Ways and Means Committee announced on September 23 that the committee has scheduled public hearings on an excess-profits tax, beginning on November 15, 1950. In the meantime, the staff of the Joint Committee on Internal Revenue Taxation and the staff of the Treasury Department are to confer jointly on this question in the hope that such conferences may result in the preparation of a report on excess-profits tax proposals which could be used as a basis for testimony before the committee. It is thought that this procedure may aid in the draft of an excess-profits tax bill for introduction in the House when Congress reconvenes on November 27.

Jan 11, 1950

By T. A. Henrie, E. K. Kleespies

Carbon reduction of rutile and ilmenite in nitrogen and ammonia atmospheres was studied as a method of preparing titanium nitride . Ammonia was a better nitriding agent than nitrogen . The contact between the solid reactants , carbon and rutile , was a prime factor in nitrogen atmospheres and was of lesser import in dissociated ammonia . The reduction process for conversion of rutile to the nitride required carbon . The nitriding of ilmenite- carbon mixtures produced titanium nitride and elemental iron .

Jan 1, 1964

By A. Gene Collins

This report discusses some of the chemistry and geochemistry of cesium and rubidium. Knowledge of the cesium and rubidium content of oilfield waters aids in resolving the origin of waters and petroleum, exploring for petroleum and other valuable minerals, discovering water pollution sources, and augmenting the knowledge of geologic formations. The methods described in this report permit the detection of less than 0.01 mg/l of cesium and/or rubidium in a complex oilfield brine or water. Solvents possessing high-dielectric constants were evaluated for their ability to extract cesium and rubidium tetraphenylboron from oilfield waters and for their flame emission characteristics. Nitroethane was selected and used for the extraction and flame spectrophotometric determinations because it gave the highest sensitivity. Cesium 137 and rubidium 86 were used to determine the extraction efficiencies, which were about 87 percent and 58 percent respectively using a single 10 ml nitroethane extraction from a distilled water matrix. The standard deviation of the determination was 0.0008 mg for cesium and 0.0007 mg for rubidium in the 0.01 mg range.

Jan 1, 1965

By J Mukhopadhyay, J Gutzmer

Most world-class high-grade (60 - 67 wt per cent Fe) hematite iron ore deposits are the product of enrichment of Precambrian iron-formations but processes responsible for enrichment are still unclear. Different models, ranging from syngenetic and diagenetic (King, 1989), deep-seated hydrothermal (Powell et al, 1999; Barley et al, 1999; Taylor et al, 2001; Gutzmer et al, 2002) and ancient supergene (Morris, 1980; 1985; Van Schalkwyk and Beukes, 1986) to modern supergene (MacLeod, 1966) have been suggested. The high-grade hematite deposits stand in contrast to martiteûgoethite ores which are generally accepted to be the result of supergene enrichment of iron-formation because they are found along Cretaceous to Tertiary lateritic weathering profiles (Morris, 1980; Harmsworth et al, 1990). Uncertainties about the origin of the high-grade hematite ores appear largely due to the monomineralic composition of the ores. They are almost exclusively composed of hematite (as microcrystalline hematite and martite), a mineral with wide stability field and very simple chemical composition that reveals little about its origin. Second, many of the deposits have been overprinted by later deformation and chemical weathering obscuring primary ore characteristics and zonation (Taylor et al, 2001). Third, surprisingly few detailed geological studies have been undertaken on the deposits with the aim of unraveling ore genesis. Most studies focus on the present-day structure of orebodies and their general physical-chemical composition for mining and beneficiation purposes. A more thorough understanding of the origin of high-grade hematite iron ore deposits may be gained by combining available mining-orientated data with systematic petrographic-geochemical analyses of different ore generations and hematite phases. This paper presents a first summary of results of an ongoing study, started some two years ago, of high-grade iron ore deposits in South Africa, India and Brazil, including a comparison with the rather well studied deposits of the Hamersley Province in Australia.

Jan 1, 2002

By Chetan D. Savani, Mike K. Muchard

The necessity to evaluate undocumented foundation lengths is essential in assessing the useable life, need for scour protection, retrofitting, or full reuse of existing bridge foundations. For this purpose, Parallel Seismic Testing (PST) has the best accuracy and is applicable to the widest range of foundation configurations used in bridge construction of any test method. Although not limited to bridges, PST case studies are presented involving two bridges. To preface the case study discussions, an overview of the PST method is given along with its results and analysis thereof. In one of the cases, we were afforded the rare opportunity to see the existing piles being extracted long after the PST testing program was completed. The resulting Class A prediction reaffirms the accuracy of the method. Versatility of the PST method is also exemplified in the two cases presented, where unique situations from complex foundation systems were overcome by analysis to provide successful results.

By D. Tang

The froth zone in a flotation cell is recognised as a region which contributes to the overall flotation performance. Froth recovery is a measure of the efficiency with which the froth phase delivers particles arriving at the pulp-froth interface to the concentrate. Poor froth recovery in scavenger stages is generally attributed to poor froth stability. The key indicators of froth performance: froth recovery, entrainment and water recovery were measured in an OK3 pilot cell installed at a zinc concentrator in Australia and supplied with scavenger feed. Cell hydrodynamic and pulp chemical conditions during the operation of the cell were also measured as well as bubble growth across the froth phase. The objective of the work was to assess the impact of a number of commercial frothers on the froth performance in the OK3 cell and assess the suitability of using bubble growth as an indicator of froth stability.

Jan 1, 2014

By F Debidin

The progressive rise of an H-pile during driving of an adjacent pile is described in this case history in which piles 15 to 18 m long were driven to end-bearing for the foundations for a 230 m long building. The use of a reaction beam-soil anchor system for compression load tests is discussed. The results of static load tests to determine pile capacity are compared with those obtained by the Pile Driving Analyzer and by theory. Unusual high temporary compressions were observed by field control staff. Proof testing was necessary to determine the need for restriking of some piles in which rise had occurred.

Jan 1, 2010

By Michael S. Roscoe

In order to more accurately predict longwall surface subsidence over the Pittsburgh No. 8 Coal in Eastern Ohio, North American Coal Corporation's Quarto Mining Company undertook or participated in several subsidence studies. Due to the changing roof geology and rapid variations in the amount of cover two separate areas were investigated at two different mines to determine the subsidence response if any to these changes. Data generated from these studies were compared with NCB derived,data for accuracy and then used to predict subsidence under houses, gas lines and other critical man made structures. The following report summarizes the results of these studies as well as the subsidence case histories of gas lines, transmission towers, houses and water wells. Problems that were encountered during both phases of this process (investigation and subsequent application) are also included.

By Leonardo Rosas Sánchez, Darío Ángel Bulla

"The two track road sector between Cisneros-Loboguerrero (having a length of 14 km and 11 short unidirectional tunnels) is a new highway still on construction located along the existing Highway Buga – Buenaventura (Colombia). Due to the steep topography, difficult geological/geotechnical conditions, the traditional portal construction approach was impossible to be implemented in eleven (11) of the twenty two (22) portals. In this specific project, the skewed portal approach was developed as the optimal and more effective solution. The construction time and costs of portals were reduced in 21 months and 75%, respectively. At the same time, the natural equilibrium of the slopes was maintained, thus, facilitating adequate safety factors along the useful life of the project. This document pretends to show a detailed design experience (and the construction of the entry portal of tunnel 11 (left)). INTRODUCTION The Cisneros-Loboguerrero project is a 14 km length dual lane highway, connecting productive zones with the Pacific Ocean along the current Bogota-Buenaventura highway as shown in Figure 1. The project is located at the northern side of the Dagua River Valley. The preliminary design suggested constructing portals under challenging topographical conditions, i.e., slope cuts having heights between 50 to 100 m (some having slopes > 100%) requiring complex developments and having very high risks.The entry portal of tunnel 11 (left) was the first portal successfully built by implementing the skewed portal approach. Later, this approach was used as a model for the construction of the other ten (10) portal having similar topographic and geotechnical conditions. The development of this new alternative provided a considerable reduction on the construction time of portals, thus relieving a critical path in this project."

Jan 1, 2016

By J. M. Bray, R. R. H. Cohen, P. Kiousis, S. R. Al-Abed

"INTRODUCTION Conventional tailing storage and management practices typically utilize engineered facilities, such as ring dikes and valley impoundments. To reduce the environmental costs associated with disposing of mine wastes in tailing storage facilities (TSFs), several beneficial re-use strategies have been developed over the years. For example, thickened tailings have been used for paste backfill. It is common for tails to comprise up to 60% of the material’s total weight and it has been estimated that TSF volumes can be reduced by 60% when using this strategy, (Benzaazoua, et al. 2004). Other beneficial re-use strategies have produced unpaved temporary access roads, hot and cold asphalt, chip seals, self-compacting concrete, and golf course sand traps. This project sampled mine tailings from two different TSFs in Colorado and produced structural concrete that could potentially be used for commercial foundations, sidewalks, and paved roads. The tailings were substituted for the fine aggregates typically found in conventional concrete. The two main objectives of this study were to investigate the structural integrity of the produced concrete samples and the leaching of heavy metals from the resulting concrete. The ratio of tailings to fine aggregate (T/FA) was carefully studied to find if there was a correlation between the substitution rate and the structural integrity. The potential maximum substitution rate was also investigated for the produced concrete specimens. The potential of leaching mining impacted water (MIW) was evaluated by comparing the leachability of the raw mine tailings to the encapsulated tailings by using standard shake extraction prediction tests. MATERIAL AND METHODS Materials The four components that make up the concrete mix design for this project are: cement, coarse aggregate (gravel), fine aggregate (sand and mine tailings), and water. The type I/II ordinary Portland cement (OPC), gravel, and sand came from local cement and concrete companies in Denver, Colorado. Mine tailings were collected from two different TSFs in the Rocky Mountain Region, where Pride of the West TSF in Silverton, CO will be denoted as Site A. The primary metals of interest at the mill site are gold, silver, lead, copper, and zinc. The location of Site B will not be mentioned in this report due to confidentiality agreements with the mining company"

Jan 1, 2016

By Alisson Paulo de Oliveira

Incentivado pela diversificação dos produtos em aço, a demanda por graus cuja composição química esteja próxima da faixa peritética, tais como os aços HSLA (High Strength Low Alloy) e AHSS (Advanced High Strength Steel), tem aumentado. As crescentes exigências nas propriedades mecânicas e a redução de custo nas ligas são as razões para que esses aços sejam projetados próximos à faixa peritética, com o teor de carbono entre 0,09 e 0,16%. A produção de placas do aço ASTM A588-B, com o teor de carbono visado igual a 0,10%, apresentava expressiva variação do Nível de Aço no Molde (Ou Mould Level Fluctuation, MLF), aumentando a probabilidade de ocorrência de “Break-Out” (Rompimento de Pele) e a redução da qualidade de superfície das placas, com eventual ocorrência de Trincas Longitudinais. Outra limitação é a impossibilidade de troca de largura das placas, dependente da estabilidade do processo de Lingotamento Contínuo. Serão discutidas as ações tomadas visando a redução do MLF, baseada em alterações no Projeto de Liga, a comparação entre variáveis-chave do processo de Lingotamento Contínuo de Placas em dois cenários de Projeto de Liga além dos impactos em características de Propriedades Mecânicas do produto laminado, no caso bobinas processadas em Laminador Steckel.

Oct 30, 2017

By Jie-qun Zhai, Jian Jia, Ke Yang, Xiao-lin Xie, Yu Zhang

"With cities’ development, underground space exploitation presents a need for bigger and deeper constructions now. Technical problems founded during the construction of deep foundation pit support become more and more important. The supporting system has to cut or partly cut off hydraulic connection outside and inside the foundation pit, control the ground settlement caused by dewatering and make sure safety of foundation pit and its surroundings. Some preliminary study and application of ultra-deep soil reinforcement methods have been conducted in Shanghai’s deep excavation engineering. On the basis of engineering practice of ultra-deep foundation pit in Shanghai, some field and laboratory test, this paper analyzes effects of different ultra-deep soil reinforcement methods and their influence characteristics of surrounding environment. It also summarizes these methods’ sealing effect, construction and economic efficiency and concludes their characteristicsINSTRUCTIONShanghai is formed from marine sedimentation. In Shanghai, from earth’s surface to 30~40m underground, soil is mainly consist of soft clay with 40% moisture content. There are also many thin silty-sand layers in the earth, so the soil is both soft and permeable. Under 40m, soil is mainly thick silty-sand layers and fine-sand layers with medium density and confined groundwater whose water head is about 7m high.With the rapid development of Shanghai’s municipal construction and high-rise buildings in the recently ten years, the number of underground structure including subway station, tunnel and high-rise building basement are constructed rapidly. Due to the permeability and softness of Shanghai’s soil, it is necessary to reinforce soil to make sure the safety and high construction rate of engineering project in Shanghai.Because of deeper excavation depth and bigger excavation area in Shanghai, ultra-deep soil reinforcement is used preliminarily in Shanghai. Combining with engineering practice of ultra-deep foundation pit in Shanghai and employing field and laboratory test, this paper analyzes effectiveness of different ultra-deep soil reinforcement methods and concludes these methods’ characteristics and their applicability. All this can guide further application of these methods."

Jan 1, 2015

By N Takamatsu

The environments surrounding the iron and steel industry have changed greatly in recent years. Reported in this paper are the technologies adopted by the Japanese iron and steel industry to fititself to change in global steel demands, degradation of iron ore and coal, prolonging service life of the facilities and requirements of energy saving. In addition, innovative technologies for CO2 emission control in iron making processes are also discussed.

Jul 11, 2011

By X. -G. Chen, K. Liu

Nowadays, great interests are rising on aluminum alloys for the applications at elevated temperature, driven by the automotive and aerospace industries requiring high strength, light weight and low cost engineering materials. As one of the most promising candidates, Al-Mn-Mg 3004 alloys is found to possess considerably high mechanical properties and creep resistance at elevated temperature resulted from the precipitation of a large number of thermally stable dispersoids during heat treatment. In present work, the effect of Fe contents on the evolution of microstructure as well as high temperature properties of Al-Mn-Mg 3004 alloys has been investigated. Results show that the dominant intermetallic changes from a-Al(MnFe)Si at 0.1 wt.% Fe to Al6(MnFe) at both 0.3 wt. % and 0.6 wt. % Fe. In the Fe range of 0.1 to 0.6 wt.% studied, a significant improvement on mechanical properties at elevated temperature has been observed due to the precipitation of dispersoids, and the best combination of compression strength and creep resistance at 300°C is obtained in the alloy with an intermediate Fe content (0.3 wt.%) with finest size and highest volume fraction of a-Al(MnFe)Si dispersoids. The superior properties obtained at 300°C makes 3004 alloys more promising for high temperature applications. The relationship between the Fe content and the precipitation of stable dispersoids as well as the materials properties has been discussed.

Jan 1, 2015

By H. E. Powell, T. E. Hill, W. A. Calhoun

The object of this investigation was to determine the effectiveness of certain cationic flotation collectors , Ethomeens , in recovering fine particles of lead minerals from mill tailings at a grade equal , at least , to that of the mill feed ( 1.7 percent lead ) . The Ethomeens , derived from tertiary amines having one fatty alkyl group and two polyoxyethylene groups attached to the nitrogen , were evaluated by bench- scale flotation tests . The 14 Ethomeens tested consisted of four groups : Coco amine , soybean amine , tallow amine , and stearyl amine . The best results were obtained with coco amine C / 12 , soybean amine S/ 15 , tallow amine T / 12 , and stearyl amine 18/20 . From a feed containing 0.23 percent lead , rougher concentrate grades of 2.12 to 3.89 percent lead were obtained , with recoveries of 17.3 to 27.5 percent of the total lead . Some of the lead mineral particles recovered had diameters of less than 1 micron . In comparative tests , the Ethomeens , or polyethoxylated amine types of cationic surface active agents , were more selective than conventional xanthate collectors for flotation of slimed lead minerals .

Jan 1, 1964

By G. E. Sreedhar, R. Kumar

The pockets of high silica blue dust across the entire high grade hematite deposits in the Bailadila sector bothers the excavation activity due their iron content, which is higher than the threshold value specified by the Indian Bureau of Mines and the agony of stacking them separately due to their fragile & powdery nature. The physical nature of blue dust and its negligible alumina content makes these a potential source of hematite, which is a blessing in disguise. As most of the particles are in the form of an independent grain making it appropriately suitable feed for dry magnetic separation and thus the dry beneficiation has turned a bane into boon by enabling to produce concentrate either suitable for using as DSO or amenable for blending. The emphasis on carrying out dry beneficiation studies in the present context serves the purpose of mineral conservation, mitigates the issues of excavation and stacking as well as conservation of water resource. This paper describes the laboratory and pilot scale dry beneficiation studies carried out on blue dust of 48 – 60%Fe and Silica up to 30% at 25 Kg/hour to 400 Kg/hour, resulting in production of concentrate assaying 60 – 65%Fe. INTRODUCTION High silica blue dust (HSBD) is associated with Banded Hematite Quartzite (BHQ) and is available in abundance in various pockets across the Iron ore body in the Bailadila region of Chhattisgarh state. High Silica Blue dust occurs in the form of free granular particles and also as friable lumps. The chemical quality of this falls under sub-grade category (45 – 55%Fe) and as per the guidelines of Indian Bureau of Mines, these are to be stacked and conserved as future resources of Iron if it can’t be utilized in the present circumstances. Due to its friable nature, stacking of HSBD is a challenge and it is also compounding the problem by polluting the air under high velocity wind conditions. Because of its physical nature and occurrence in pockets pose challenge to systematic mining. The existing processing set up of the operating mines is designed to treat either Direct Shipping ore (DSO) or Run-of-Mine (ROM) have grade >60% Fe. The present practice of beneficiating iron ore fines (<1 mm) comprise combination of two or more processes such as desliming, hydraulic classification, magnetic separation and flotation apart from requirement of grinding depending on liberation characteristics. The HSBD which is predominantly occur as free granular particles, is significantly low in its alumina content. This gives us an opportunity to utilize them by exploring a suitable beneficiation process so that the concentrate produced can be used as a sweetener for alumina rich iron ore/concentrate. Thus, in the present study, an attempt has been made to adopt dry high intensity magnetic separation technique to explore the amenability of the high silica blue dust for beneficiation.

Jan 1, 2019

By Ali Kahriman, Olivio Angelini, Ibrahim Sefer, Burak Ekmen, Koray Arpak, Ertugrul Kaya, Yucel Karakus, Abdullah Sak, Aziz Ozdemir

In recent years, in order to bring solution to traffic intensity arising from transportation problems and facilitate public transportation in the modern world in paralel to urbanization and to the increase in population, it’s well known that, the construction of Access tunnels is inevitable. The driving of the tunnels is a subject of special interest in the technique of rock blasting. The essential factors in terms of tunnel driving and safety in tunnel blasting that is applied in metropolitan areas, an in depth knowledge of ground vibrations and the ways of reducing them to safer levels.

Jan 1, 2010

By Jingzhong Kuang, Zheyu Huang, Chuanzhou Guo, Pengfei Liu

"In this paper, scheelite and scheelite coated with Pb2+ (SC) were synthesized by chemical precipitation with the help of ultrasonic. The role of the Pb2+ on scheelite was evaluated. Additionally, the dissolution behavior of minerals and the adsorption mechanism of collectors were investigated systematically via SEM, XRD, EDS. The results indicate that the ultrasonic cavitation can promote the formation of scheelite with large particle size and high crystallinity. Due to the exchange of WO4 2- and OH-, the dissolution of scheelite are not in a 1:1 equivalent amount by chemical formula and the concentration of WO4 2- is higher than that of Ca2+ in the solution because Pb2+ promotes the transfer of WO4 2- from scheelite surface into the solution. The dissolution of scheelite is an endothermic reaction and its enthalpy reaches the maximum value of 692.59J·mol-1 at pH=8~10. But the coating of Pb2+ changes the thermal effect of scheelite in the solution and the dissolution of SC is an exothermic reaction with the dissolution enthalpy of -262.30 J·mol-1. At pH=8~10, the adsorption capacity of sodium oleate and salicylhydroxamic acid on the surface of SC is higher than that of scheelite which delivers that Pb2+ contributes to the scheelite surface dissolution and enhances the adsorption of collectors on the mineral surface, thus achieving activation.INTRODUCTIONIn modern society, tungsten is a type of quite important rare metal and also a strategic resource. Because of its low vapor pressure, high melting point, good electrical and thermal conductivity properties, it is widely applied in high-temperature technology, lighting, machine and engine construction (Zhao,Z.W, 2013; Yan, W, 2017; Ilhan, S, 2013). Both scheelite and wolframite are the major tungsten deposits. With the depletion of easily-processed wolframite, scheelite has drawn a great deal of scientific and industrial attention. Scheelite can be recovered by flotation due to the metathesis of polarity and chargeability on minerals surface via adding regulators and collectors."

Jan 1, 2018