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By G. P. Karmakar, K. K. Chandan

"The drilling mud is an essential part of the drilling process, which plays a major role in keeping safe and efficient oil and gas well drilling. In the oil industry, bentonite clay dissolved in water produces the simplest type of drilling muds. Bentonite clay contains montmorillonite particles. These particles are dispersed uniformly in water and such dispersions are used in various industrial products like paints, ceramics, pesticides and drilling muds. The bentonite clay easily dissolves in water and increases the viscosity of the water, which is one of the most important properties of a drilling mud. Bentonite has the highest swelling capacity, which is responsible for building up of the viscosity of the clay-water system. The flocculation behavior of bentonite is one of the major concerns for the performance of the water-based drilling mud in the oil and gas well drilling process. The behavior of drilling mud greatly depends upon the quality and quantity of bentonite clay, as well as the additives that are used in their formulations. In this work, a comprehensive study has been carried out to find out the effect of added polyacrylamide (PAM) polymer, surfactant, pH and salt concentrations on the dispersion/ flocculation characteristics of bentonite clay-water system. It has been observed that the increase in PAM dosage reduces the residual turbidity and improves the settling rate of the bentonite particles. The flocculation rate has also been found to be better under higher pH conditions. The combined effect of salt concentration and PAM dosage improved the overall flocculation efficiency of the system.INTRODUCTIONIn the oil industry, bentonite clay dissolved in water produces simplest type of drilling muds. Bentonite clay containes montmorillonite particles. These particles are dispersed uniformly in water. Such dispersions are used in various industrial products like paints, ceramics, pesticides and drilling muds (Akther et al., 2007). The bentonite clay easily hydrates in water and increases the viscosity of the mud system (Razi et al., 2013; Meng et al., 2012). Bentonite clay in the drilling mud increases the viscosity which is one of the most important prop erties of a drilling mud. Bentonite has the highest swelling capacity, which is responsible for the building up viscosity of the clay-water system (Sonmez et al., 2013). The drilling mud is an essential part of the drilling process, which plays a major role in keeping a safe and efficient oil or gas well drilling (ASME, S. S. C., 2005). The flocculation behavior of bentonite is one of the major concerns for the performance of the water-based drilling mud in the oil or gas well drilling process. This behavior of drilling muds greatly depend upon the quality and quantity of bentonite clay, as well as the additives that are used in their formulations (Yu and Amanullah, 2005; Akther et al., 2007). Bentonite particles form aggregate under certain conditions including high temperature, and high concentration (Luckham and Rossi, 1999). If the quality of bentonite is not sufficient to accomplish intended viscosity of the muds, it is essential to add certain additives to increase the viscosity and prevent aggregation of the system (Razi et al., 2013). The anionic polymer bearing sample can build up inter-particle bonds between the polymer and clay particles. The addition of various additives like, polymers control the dispersion and enhance the viscosity of the mud by controlling the flocculation of montmorillonite particles in bentonite dispersion (Heller and Keren, 2002; Mahto and Sharma, 2004)."

Jan 1, 2018

By Kee Jeung Lee

In this study the characteristic factors and formation mechanisms for the hydrothermal preparation of a -quartz crystal powders were investigated to find the optimum synthetic conditions. The degree of Q -quartz crystal face development depended on the relative growth rate of a particular form that varies considerably with the degree of supersaturation, the reaction temperature, the concentration of mineralizers, and the presence of seed crystals in the feedstock. Alkali hydroxides and alkali halides were found to be effective in the reactions as mineralizers, which added in order to increase the solubility of the feedstock. The fine Q -quartz crystal powders were obtained in the temperature range of 250-450% and pressure range of 100-300atm. As the concentration of mineralizers increased, the particle size of crystalline powders became smaller at lower reaction temperatures. The fractional size distribution of synthetic crystal powders was depended on the hydrothermal conditions. As the reaction time and the amount of seed crystals increased, the width of particle size distribution became narrower. The weight mean particle size was in the range of 1 to 10m. The characterization of the products were carried out using XRD. SEM. PSA, FT-IR, Raman spectrometer.

Jan 1, 1997

By M. Sahoo, P. Burke, Y. Fasoyinu, J. P. Thomson

The effects of grain refinement, mold temperature and chemical composition on the hot tearing resistance of aluminum alloys 535.0 and 206.0 has been studied by pouring constrained rod castings in metal molds. In addition, two prototype components that could be used in automotive applications were also poured from both alloys by gravity tilt-pour and low pressure permanent mold casting processes. This paper summarizes the results and issues encountered during the casting trials. It was shown that grain refinement and mold temperature ::::: 400°C reduced, and sometimes eliminated hot tear cracks in both alloys. The two prototype engineering components could be cast successfully from both alloys in metal molds. The metallurgical issues related to molten metal treatment and processing temperatures were well controlled. However, issues related to the control of hot tearing, casting and mold design must be addressed in future studies to guarantee the production of defect free castings.

Jan 1, 2006

By D. S. Salonine

Aluminum alloys offer a wide range of capability with a unique combination of advantages that makes them the materials of choice for numerous products and markets. One of the most important applications is their use as the primary structure and outer envelope in aerospace vehicles. Wide and thorough studies on hot working and microstructure evolution of aluminum alloys have been made in Russia. The most important appear to be: - introducing the structure diagrams in strain rate - temperature coordinates which show areas of different microstructures (non-recrystallized, recrystallized, and mixed) after the hot deformation and the following heat-treatment for common aluminum alloys (Yu.M. Vainblat); - studying the press-effect ("structural effect" by V.I. Dobatkin); - learning the influence of hot worked substructure on aging mechanisms; conducting researches on press heat-treatment. These works allowed a deeper understanding and a better control of the mechanical behavior of aluminum products. Comparisons are made to equivalent developments in Europe and America.

Jan 1, 2004

By J. R. Perumareddi, V. S. Sastri, M. Elboujdaini

It is well known that high strength steels used in aerospace industry, are generally susceptible to hydrogen embrittlement during surface treatment such as electroplating with zinc on cadmium. Hydrogen embrittlement reduces ductility and results in brittle fracture rather than failure by plastic deformation. Hydrogen embrittlement of high strength steels is mitigated by surface treatment such as plating with other metals. Data on the hydrogen contents of steels before and after surface treatment by hot extraction-thermal conductivity, secondary ion mass spectrometry (SIMS) and UV-visible spectroscopy along with the mechanism are presented.

Jan 1, 2006

By J. Y. Xu

A mutant of Phanerochaete chrysosporium, which is capable of degrading lignin, was bred by ul-traviolet ray irradiation and this mutant strain shows high capability of degrading of lignite. The degradation ratio of original Yima lignite and nitric acid treated Yima lignite by this mutant are 37.6% and 51.62%respectively, whereas those by the original strain are 31.84% and 32.55% respectively. XRD and FTIR analyses of the lignite converted product show that its polymerization degree and average molecular weight are both greatly reduced. The content of the functional groups is also been altered.

Jan 1, 2014

By Strathmore R. B. Cooke

That calcium will activate quartz for flotation with anionic collectors such as soaps has been known for a number of years,1 2 3 and the method has been applied to the concentration of various iron ore 4 5 6 as well as to other materials. Clemmer gives the permissible pH range for the activation of quartz by calcium as between 9.5 and 12.5 with an optimum value of 11.0, and Hertzog7 has determined the calcium abstraction of iron ores and of Ottawa sand, but otherwise little quantitative data are available. The purpose of the present investigation was to determine those conditions under which dilute solutions of calcium chloride will activate quartz for anionic flotation and to determine the amount of calcium ion adsorbed by quartz. Those variables, the influence of which was primary, such as calcium, sodium, and hydrogen ion concentrations, were studied. Other factors which influenced the results are discussed in the description of the experiments. Three different experimental methods were used to determine the activation of the quartz. The first method was to treat a sample of ground, deslimed quartz with solutions of calcium chloride and sodium hydroxide, and to determine the calcium adsorbed by chemical analysis of the solution. Ad- vantages are that a direct value for the

Jan 1, 1949

By Xian-Dong Zhou, Guo-Sheng Sun, Jianzhong Luo, Hong-An Guan

"Oxygen utilization rate of the pretreatment process which adopts biological contact oxidation method for slightly polluted supply water is relatively low, less than 10%, usually lower than 3%. So the aeration amount is not determined by calculated value of oxygen demand when doing process design, but by the ratio of gas and water. The aeration way of the biological pretreatment process for slightly polluted supply water was introduced in this paper. In the foundation of the principles of mass transfer kinetic theory and experimental data, the change law of DO (dissolved oxygen) and ammonia in the aeration tank was analyzed to explore aeration method which will help to improve the overall effectiveness of handling capacity.IntroductionThere are many kinds of filler used in the biological contact oxidation process, such as flexible solid filler, composite filamentous filler, powdery clay filler, particle ceramic filler and so on. Regardless of the different forms of filler, there are a couple of common points in the function of the aeration[1,2]: (1) The aeration process in biochemical tank not only provides adequate oxygen for the biological reaction, but also plays as a role of stirring water; (2) Biochemical reactions mainly happen in the upper reaches of tank, but seldom at down-streams.This paper, from the perspective of changing aeration way, discussed the feasibility of improving the effectiveness of biochemical reactions without increasing aeration amount, which would have some leading significances for the operation and management of similar projects."

Jan 1, 2008

By M. V. Sowmya

Batch biosorption experiments were carried out for the bio-remediation of Cr (VI) ions from aqueous solutions using Serratia marcescens, a Gram negative, heterotroph and Gram positive bacterial isolates from a chromite mine. The influence of various experimental parameters such as contact time, pH, concentration of Cr (VI) ions and amount of biomass was evaluated with respect to the uptake of Cr (VI). The bio-sorption of Cr (VI) was found to be quite rapid and the percentage biosortion was found to increase with increase in the equilibrium chromium concentration. The free energy of biosorption of Cr (VI) was estimated to be in the range of -23 to -25 kJ/mol for the chosen bacteria. The uptake of chromium by the bacteria was confirmed by EDX and FTIR spectroscopy. As a follow up of this study, bacterial strains resistant to hexavalent chromium were isolated from a chromite mine in Karnataka, India and identified as Arthrobacter sp., Micrococcus sp. and Exiguobacterium sp. using 16s rRNA sequencing. The efficacy of the bacterial isolates for Cr (VI) uptake was assessed and over 90% bioremoval could be achieved for Serratia marcescens and Micrococcus sp. isolate. Possible mechanisms of chromium uptake by the microorganism are discussed. Keywords: bioremediation, hexavalent chromium, biosorption, bioreduction

Sep 1, 2012

By Bian Xue, Wu Wenyuan

In order to recycle the iron and rare earth from the Baotou tailings, a roasting method was developed involving the addition of C, Ca(OH)2, and NaOH, designed to both decompose the rare earth minerals and convert haematite into magnetite and allow its recovery. The effect of various parameters such as roasting temperature, roasting time, C addition, Ca(OH)2 addition, and NaOH addition on the reduction ratio of haematite (iron sesquioxide) and decomposition ratio of rare earth were investigated. The results showed that the reduction ratio of haematite and the decomposition ratio of rare earth could be as high as 85% and 95% respectively when the roasting temperature was 650°C, roasting time was 60 min, Ca(OH)2 addition was 4%, NaOH addition was 3%, and C addition was 1.5%.

Jan 1, 2014

By Marcela Gotelip Barbosa

Pellets are the main iron input to the blast furnace at ArcelorMittal Lazaro Cardenas iron and steel making facility in Mexico. Pellets are made at this facility using the concentrates generated and shipped from their captive mines viz., Las Truchas, Pena Colorada, Volcan Sonora. The concentrating plants, after grinding the ore to the liberation size, use magnetic separation and flotation to reject the silica, sulphur and phosphorous impurities. At Volcan Sonora Mines, the ore is contaminated with phosphorous minerals, and hence, after magnetic separation, the phosphate minerals are floated using anionic carboxylate collector (sodium oleate). Apart from floating the phosphate minerals, the sodium oleate also has some tendency to smear on the iron bearing mineral surfaces leaving a hydrophobic surface, which is expected to reduce the green pellet strength due to absorption of ultrafine sized air bubbles on these surfaces, and further generate higher levels of dust during the induration process. In order to alleviate this industrial problem, comparative studies were carried out on the concentrates from magnetic separation using reagents from synthetic sarcosinate and carboxylate family collectors. Results have indicated that the sarcosinate family members not only were found as replacement to carboxylate collectors, but also reduce the phosphorous content below the values achieved with oleate, thus have considerable benefits in the downstream steel making process. Based on the results, plant runs are being taken up at Volcan Sonora. In this article, the laboratory results obtained on iron grades and recoveries, and phosphorous rejection using both the reagents are presented.

Aug 1, 2018

By R. N. Chakravorty

Early detection of spontaneous combustion is of utmost importance in underground coal mining to prevent major disruptions of production and to ensure a safer working environment. This paper presents the work done in developing a suitable system for the early detection of heating in a hydraulic coal mine. Laboratory studies on the products of oxidation for Balmer 10 seam coal showed that a significant amount of carbon monoxide is produced during the early stages of heating and that detection methods based on the analysis of other gases, such as hydrogen, ethane or ethylene, are not a better alternative for this coal. The four-point carbon monoxide monitoring system recently installed at the hydraulic mine is discussed in this paper. It is believed that by studying the trend of carbon monoxide concentration in the mine air, it will be possible to detect heating at an early stage. Field tests carried out so far have indicated that infra-red technology will prove to be a powerful tool in the hydraulic mine, particularly for locating hidden oxidation or fire in cracks, fissures, underground workings and coal outcrop areas before it spreads extensively. The project is jointly sponsored by EMR, CANMET, Mining Research Laboratories and Kaiser Resources Ltd.

Jan 1, 1978

By G E. Smith, G N. Lye

Wall control blasting practices are necessary to reduce the impact of blasting on mine faces but can also have a significant negative impact on mine productivity and operating costs. The conventional practice in deep open pit mines is to use so-called trim blasts adjacent to pit walls. To provide burden relief these trim blasts have fewer rows than full production blasts and are fired to a cleared free-face; hence they are termed æunchokedÆ. This practice leads to scheduling constraints on the pit operations and can cause ore dilution due to excessive muckpile movement. The use of such trim blasts stems from the perception that increased wall damage results from æchokedÆ blasts. These concerns are based on the unproven assumptions that blast vibration levels and explosive gas penetration increase with increased blast burden and face confinement. This paper describes work undertaken as part of a major investigation into wall control blasting at the KCGM Fimiston Mine, Kalgoorlie, Western Australia. It details a study to assess damage effects due to blast burden. Borehole air pressure measurements and borehole video camera inspections were done behind a series of single blastholes drilled with varying burden distances, as well as behind a dedicated trim blast and a full production blast. It was found that the measured damage effects, including visible rock cracking, dilation, and the limited extent of gas penetration behind the blastholes, did not vary significantly with burden or blast type for the cases tested. This result was in complete agreement with detailed vibration measurements conducted by Blair and Armstrong (2001) during the study, which found that vibration was independent of blast burden. As a result of these investigations, changes to the blasting practices at the mine were implemented. Dedicated trim blasts and free-face blasting have been replaced by modified production blasts and the practice of æchokingÆ blasts has been introduced. This has resulted in a significant improvement in productivity and cost savings without compromising pit wall integrity.

Jan 1, 2001

By D. Hongjun

In this paper, the flotation rule and behaviors of kyanite-group polymerphous minerals were studied in modified Hallimond tube in detail. Furthermore, the energy change of collector/mineral systems before and after adsorption and the net charge densities of the atoms on the minerals surfaces were calculated by use of quantum chemistry. The flotabilities in minerals were successfully explained.

Jan 1, 1995

By Ting Ren, Jon Roberts, Zhongbei Li, Ming Qiao, Jianming Wu

Spontaneous heating of coal continues to present a health and safety hazard in underground coal mines. The influence of seam gas composition on gas flow dynamics and distribution characteristics in the active longwall goaf has not been studied in-depth, and corresponding effective proactive goaf inertization strategies for preventing potential spontaneous heating from occurring have limited investigation. To advance this knowledge, an 80-m-height goaf model was constructed and developed based on specific conditions of an Australian underground coal mine, and onsite gas monitoring data was collated to verify base model results, which allowed for various scenarios of seam gas composition to be simulated and investigated with confidence. This study involved modeling five different gas composition scenarios for the goaf atmosphere, namely, 100% CO2 (case 1), 80% CO2 and 20% CH4 (case 2), 50% CO2 and 50% CH4 (case 3), 20% CO2 and 80% CH4 (case 4), and 100% CH4 (case 5). Simulation results show that O2 is primarily distributed at the middle and upper part of the CO2- dominant goaf model, while it is mainly layered at the floor level of the CH4- dominant goaf model. N2 is superior to CO2 in the goaf inertization for the CO2- dominant goaf model, whereas CO2 performs better than N2 for the CH4- dominant goaf model. The optimal inert gas flowrates for case 1 to case 5 are 1.5, 1.75, 0.75, 0.5, and 1.0 m3/ s, and the oxidation zone area is reduced by 55.76%, 67.21%, 58.04%, 78.17%, and 81.82%, respectively. The simulation results allow for increased insight and understanding of the gas distribution patterns in the active goaf with different seam gas composition and the development of corresponding proactive goaf inertization practices, thus minimizing potential spontaneous-heating-related hazards and improving mining safety.

Sep 26, 2023

By G. Rajesh

Mathematical modeling of bioremediation has gained importance as it is used as an optimization tool for the remediation process involved in contaminated sites. The bioremediation of Cr(VI) has been studied taking into consideration the initial Cr(VI) concentration Cr(VI)ini, bacterial growth substrate concentration (S), maximum growth rate (µmax), yield coefficient (Y), half saturation constant (Ks), and inhibition constant (KI). As the enzymatic reaction is also affected by initial substrate concentration (Sini) and Ks, different ratios of (Ks/Sini) are analyzed. As the inhibition constant (KI) is not constant for all the enzyme reactions and it varies with Cr(VI)ini, the correlation between (KI) and Cr(VI)ini is developed. A set of differential equations pertaining to bioremediation of Cr(VI) has been solved using FORTRAN 90 program adopting the model developed. The results are verified with the experimental data from the literature and a good correlation has been obtained between the experimental data and the model predictions. Keywords: bioremediation, hexavalent chromium, mathematical model, inhibition kinetics

Sep 1, 2012

By Chan Min Yoo, Kiseong Hyeong, Inah Seo

INTRODUCTION One of the major concerns for deep seabed mining is its environmental impact, from the disturbance of benthic communities due to the mining activity to the disposal of mine tailings back to the ocean. Yet a significant amount of waste materials would be produced from the on-deck processing on the mining platform, all the materials that produced on the mining platform are to be shipped to the land unless the related regulation and guidelines are developed by IMO and ISA (ISA, 2018). Still, ecotoxicology data for the deep seabed minerals from case studies in deep-sea tailings disposal (DSTD) and submarine tailings disposal (STD) sites are lacking and all other related aspects are also largely unknown. This year, the Republic of Korea has started a research project for the more comprehensive understanding of chemical and physical properties of mine tailings from the on-deck processing and the possible environmental impacts on the marine organisms after its disposal. Based on the scientific data collected from this project, Korea would be able to make recommendations for the methods and technical standards for the deep seabed mining discharges. The subjects of this project are threefold: to understand the physical/chemical properties of the tailings, to model the dispersion of particulates after the disposal, and to assess its impact on the marine ecology. Laboratory Experiments Producing Mine Tailings First, the possible waste materials are produced by mimicking the collecting and dressing processes at sea. The polymetallic nodules (PN) would be mined by using a collector lifting the crushed nodules out of the bottom sediment, and the bottom water, accompanying sediment, and the fine nodule particles which are too small to be recovered would be discharged to the ocean and thus are considered as tailings (Schriever and Thiel, 2013). In the laboratory, PN is crushed into the fragments smaller than 2 cm, abraded in the water using the rock mill, and then sieved to obtain the fine particles to be disposed.

Jan 1, 2018

By Jie Li, Shu Yang, Zhongliang Tian, Xun Hu, Yanqing Lai

The purity of the electrolyte has an important influence on the content of the impurities in electrodeposited silicon. In this paper, effects of electrolysis temperature, current density and the time on the concentrations of two important impurities: phosphorus and iron in the electrolyte were investigated during the purification of Na3AlF6-10%K2SiF6-AlF3 melt. It was observed that the concentrations of P and Fe in the electrolyte decreased with the electrolysis temperature, current density and the electrolysis time increasing. X-ray fluorescence (XRF) of the electrolyte shows that the concentrations of P and Fe decrease from 4.2ppmw to 1.3ppmw and 204.0ppmw to 42.6ppmw, respectively. The removal rates of P and Fe are 69.08% and 79.12% when the electrolysis was performed for the duration of 3 hours and at a current density of 20mA·cm-2 while the operating temperature was 1225K.

Jan 1, 2015

By L. Alagha, O. Molatlhegi, S. Khatibi

"In the present study, the effect of organic/inorganic (hybrid) polyacrylamide polymer on fine coal flotation was investigated. Raw coal samples contain about 37% of ash-forming mineral at a feed size of -75 + 38 um were subjected to flotation tests in the presence of in-house synthesized hybrid Al(OH)3-PAM at different polymer dosages and pH values. Results show a significant improvement in both combustible recovery and ash rejection at 1 ppm polymer dosage. Further improvement of combustible recovery was obtained when flotation was performed at pH 5. Interfacial properties of coal particles before and after flotation were examined through electrokinetic (zeta potential) measurements of coal/water slurries. Zeta potential vs. pH curve were established and compared. In the case of raw coal/water slurry, zeta potential-pH curve resembles the ash-forming minerals (silica and clays) more than coal. After Al(OH)3-PAM-assisted flotation, the zeta potential of froth/water slurry shifted to more positive values point which strongly indicates significant removal of ash-forming minerals from coal by Al(OH)3-PAM. INTRODUCTION Coal has been a major commodity in meeting the world energy demand during the past several decades (Milici et al., 2013). According to the international energy agency, global coal demand will continue to increase for the coming decades. With increasing world population, the global electricity demand would also increase as more people would get access to basic electricity especially in developing countries (Maggio & Cacciola, 2012). Due to this increase in energy consumption, operations in coal mining and beneficiation processes have been highly mechanized to meet the demands. This mechanization has increased the quantity of raw fine coal particles produced which contain high amount of ash-forming mineral matter (slimes). Aplan et al., have reported that the major constituents of ash-forming minerals in U.S.A coal are clay minerals such as kaolinite, montmorillonite and illite (Aplan, 1997). Conventional froth flotation for fine coal cleaning suffers mainly from two major problems: 1) Low recovery of ultrafine coal particles due to slime coating by ash-forming minerals, and 2) The lack of selectivity, which results in the flotation of middlings and entrainment of mineral fines in the froth (Polat et al., 2003). Slime coating on both valuable and air bubbles have been proposed to explain the observed reduction in flotation recovery especially when fine grinding is required. In this case mineral matter may be degraded to extremely fine or colloidal sizes thereby creating difficulty in the water clarification process such as flotation. Slimes inhibit bubble-particle attachment, and increases reagent consumption due to the increase in solid/liquid interfacial area, resulting in low coal recovery."

Jan 1, 2015

By Gerhard Derge

A SERIES of studies of the corrosion of tin is under way in the Metals Research Laboratory at the Carnegie Institute of Technology. The complete program includes examination of the corrosion properties of high-purity tin and the changes produced in these properties by the addition of varying amounts of alloying elements. Other studies of this subject have been made recently under the sponsorship of the International Tin Research and Development Council, but these researches have been confined largely to the weakly acid environments commonly encountered in the canning industry.1 There is little information available regarding the corrosion of tin under alkaline conditions, but such data would be of value, for a large amount of the metal is used under such conditions. The potential measurements to be described were made because they seemed to offer the most rapid method for obtaining a general view of the conditions to be encountered in such service. These experiments will also serve to establish a technique that will be of value in further studies. It must be emphasized that the results reported are those of controlled laboratory experiments and that the conclusions drawn cannot yet be applied to service conditions; rather, they point to the directions in which more exhaustive experimental work may be done to best advantage. EXPERIMENTAL PROCEDURE The first work was devoted entirely to the problem of obtaining reproducible results from a series of potential measurements. Only the methods finally adopted as standard will be described here, except when the variations from these have furnished results of interest. The cell used is shown schematically in Fig. 1. The electrolyte is contained in the vessel A (an inverted bell jar), whose ground top is fitted to the transite-board lid B. The controlled atmosphere can be admitted

Jan 1, 1938