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By A. Rawat

The removal of oxyanions of arsenic present in mine process water and drinking water to a regulatory level is a challenging problem. Recently a patented adsorbent lanthanum oxide has been developed which has shown strong specificity for the anions of arsenic. In this paper the kinetic and thermodynamic aspects of arsenic adsorption on to lanthanum oxide are discussed. Adsorption tests were performed at different temperatures using synthetic solutions of arsenic of varying concentrations. From the kinetic data and adsorption isotherms thermodynamic properties such as Gibb's free energy, standard enthalpy of adsorption, standard entropy, isosteric heat of adsorption and activation energy were determined. The results showed that temperature had a positive effect on the rate and degree of adsorption:The activation energy decreased with increase in the initial concentration thus indicating solute-solute interactions in the system. Also, the isosteric heat was found to decrease with increase in the adsorption density implying a heterogeneous adsorbent surface.

Jan 1, 1998

In spite of the efforts done in the past to implement in Codelco best practice guidelines and standards on several important sampling, assaying and variability issues, many people, particularly top managers and operators, are still not aware of the relevance of the use of the principles and practice of geostatistics, sampling theory, analytical chemistry and the understanding of processes variability from rock to cathodes. As a result, an important challenge for the sampling community is to find out the causes of this lack of awareness and to develop communication skills to influence the organisation, particularly the top management level. This situation is not affecting only Codelco; it is a common characteristic of the copper mining industry. The main cause is cultural. Judeo-Christian and occidental sciences are deterministic. This implies a disregard of process variation and the assumption that homogeneity is omnipresent. Another important aspect of the cultural challenge is education. Education is the most efficient way to transfer a system of ideas, traditions and practices. To implement proper courses of sampling theory and geostatistics and support to multidisciplinary education at universities, mining companies will improve teamwork between geologists, mining engineers, metallurgists and chemists. The improvements will imply a more sustainable and efficient mining business.

Mar 1, 2010

By J. C. Ashby

Electric utility response to certain amendments of the Clean Air Act has resulted in a production of several types of alkaline coal combustion byproducts. Alkaline combustion byproducts are gaining increasing usage for acid mine drainage mitigation as research leads to a better understanding of their beneficial applications. Since January of 1997, Mettiki Coal Corporation has been injecting alkaline flue gas desulfurization material from Virginia Power's Mt. Storm Unit #3 wet limestone scrubber into abandoned portions of the active Mettiki mine. This paper provides an overview of the key design, transportation, regulatory, and environmental issues faced in the project.

Jan 1, 1998

By R. J. R. Schaller

NO. 3 winze, the sixth shaft to be sunk on the San Antonio property, is practically a duplicate of No. 3 shaft, which was the main shaft prior to the installation of the larger hoisting equipment in 1939. It is collared on the tenth, or 1,500-ft., level, and goes down vertically to the sixteenth, or 2,500-ft., level, with a loading pocket, spill pocket, and sump below this. It is 1,000 feet east of No. 3 shaft. All ore, men, and materials are handled through the latter. The winze location with reference to the rock formation is shown in Figure 1. (In plan, this section strikes N.30°E. and cuts most of the main orebodies of the mine normal to their strike.) It is collared eighty feet inside the footwall contact of the basalt and cuts through it before reaching the eleventh level. In this location there will be no ore tied up in shaft pillars, as the closest ore to the shaft is on the tenth level, and here it is eighty feet northeast of the collar. The winze headframe and hoist-room straddle the main haulage to the No. 3 shaft, on the tenth level (see Figure 2). At no time during the excavation for the headframe and hoist-room was the general routine work of this haulage held up.

Jan 1, 1941

By M. E. Holter

"Five main lignite seams occur in the Tertiary Ravenscrag Formation in the Eastevan area, at depths of 100 feet or less. They are named, in ascending order: the Boundary, Estevan, Souris, Roche Percee and Short Creek seams. A total sequence of approximately 250 feet is represented by the coal beds and interstratified clays, silts and sands. Strata dip to the southeast at 25 feet per mile or less and trike northeast. Large areas underlain by coal seams at shallow depths are delineated. Reserve calculations are dependent on detailed information on seam thicknesses and feasible stripmining depths. The stratigraphically higher seams are thinner on the average than lower seams and this, together with the increase in elastic size fractions in higher strata, suggests a retreat of a Tertiary marine margin to the south during the closing depositional history of coal seams and associated strata."

Jan 1, 1972

By D. de la Villa

From 1989 to 1992 Rio Tinto Minera has developed and implemented a productivity program in its Huelva Plant, including Smelter, Acid Plant and Electrorefinery. This Plan was designed in order to increase productivity, reduce emissions and produce a better quality of cathodes. This paper describes investments and operating improvements involved in this project, focusing on Smelter and Acid Plants, and comments the results obtained so far.

Jan 1, 1993

By Mikko Loponen

Outotec has developed an operator training simulator (OTS) platformsuitable for various hydrometallurgical processes. The complete solution is run in the cloud, where virtual client instances can be managed on-demand. The aim is to build a generalizable model that produces coherent results even when operating outside of ideal parameters, allowing the operator to train in unsteady state conditions such as start-up and shutdown. Complex software products are commonly associated with significant development time and cost. Utilizing modular software architecture, only the control system and processmodel are tailored for theOTS,whereas modules such as user administration and cloud-based client machine spawning can be imported, shortening development time. A generic acidic pressure oxidation process (POX) operator training simulation consisting of feed preparation, autoclave, dual-stage flash evaporation and off-gas scrubbing is described. Process is simulated using Outotec HSC Sim 9 process simulator and controlled by Siemens Simatic PCS7 control system.

By R. K. Rath

The low-grade iron ore sample contains both lumps and fines. It is mostly hematitic iron ore and considerable amount of goethitic/limonitic material is present in it. The major impurities present were quartz and clay. It is observed that the iron bearing phases are poorly liberated above 300 µm and the liberation improves below 300 µm. More than 80% liberation is achieved below 106 µm. Based on the liberation data, the feed for the different beneficiation methods was prepared by stage crushed the ROM followed by grinding passing to 106µm and the ground material (-106µm) was deslimed. The underflow was subjected to various beneficiation techniques such as tabling, enhanced gravity separator (EGS), wet high intensity magnetic separation (WHIMS), and flotation and the results are discussed. All the methods studied could able to produce pellet grade concentrate with iron content of 64.5%, however, a marginal higher yield was observed for WHIMS (81%). Keywords: beneficiation, gravity, magnetic, enhanced gravity separation, flotation, low-grade iron ore, desliming

Sep 1, 2012

By A. G. Bulaev

Biohydrometallurgical technologies based on activity of acidophilic microorganisms oxidizing ferrous iron, sulfur, and sulfide minerals are widely used to extract base and noble metals from sulfide ores and concentrates. As sulfide minerals oxidation is exothermic, industrial processes are usually preformed at 40–50°C. Moderate thermophiles predominate under these conditions. Most of moderately thermophilic acidophilic microorganisms that oxidize metal sulfide are mixotrophic, i.e., they use both organic nutrients and CO2 as carbon sources. Carbon availability is crucial for microbial activity and affects efficiency of biohydrometallurgical processes. Aeration with CO2-enriched air is often used to increase microbial activity in biooxidation reactors. Organic nutrients can be used as alternative carbon source for moderately thermophiles performing biooxidation of sulfide concentrates. We performed several experiments with different sulfide concentrates to study effects of organic carbon sources on biooxidation efficiency and demonstrated that application of such organic nutrients as yeast extract (YE) and molasses made it possible to increase biooxidation efficiency. For example, addition of 0.02% YE in the nutrient medium increased biooxidation rate of pyrite–arsenopyrite gold bearing and chalcopyrite concentrates in batch mode at 45°C. YE addition increased oxidation rate of sulfide sulfur and gold recovery level from 65 to 87% and from 73 to 81%, respectively. Similarly, YE addition increased copper extraction from 47 to 54%. At the same time, YE addition increased efficiency of biooxidation of pyrite–arsenopyrite gold bearing concentrate in continuous mode. Without YE addition, oxidation rates of pyrite and arsenopyrite were 65.7% and 94%, while gold extraction was 71%. YE addition (0.02%) made it possible to oxidize 74% and 95 % of pyrite and arsenopyrite and extract 78% of gold. Addition of molasses (0.02%) similarly affected biooxidation efficiency. Thus, addition of organic nutrients in nutrient media is a promising strategy for improvement of biohydrometallurgical processes.

Jan 1, 2018

By L. R. Bottomer, G. M. Leary

"The Copper Canyon property is located in the Galore Creek area of northwestern British Columbia. Porphyry copper-gold mineralization on the property is notable for its high gold content and close spatial relationship with a distinctive suite of high level syenitic and monzonitic intrusions, and pseudoleucite-bearing volcanic country rocks. The style of alteration and mineralization is similar in many respects to the nearby Galore Creek deposits.The current geological resource of 32.4 million tonnes grading 0.75% Cu, 1.17 g/ t Au and 17.1 g/t Ag is insufficient to support a mining operation, but definition of additional reserves combined with improved transportation infrastructure in the region may change this in the future. The climate, topography and proximity to an active glacier indicate that the most likely production scenario is an underground bulk mining operation, with the ore being milled offsite.IntroductionThe property is located at 57°07' North latitude, 131 °21' West longitude, on NTS sheet 104G/ 3W, approximately 160 km northwest of Stewart and 90 km south of Telegraph Creek (Fig. 1). The Galore Creek camp and airstrip are located 6 km to the west. Current access to the property is via helicopter either from Galore Creek, or from the Bronson Creek airstrip 32 km to the south-southeast.The deposit occurs within the Boundary Ranges of the Coast Mountains, on the north side of the east fork of Galore Creek, which flows northerly into the Scud River and thence westerly to the Stikine River.Topography is rugged. In the deposit area, elevations range from 1130 m to 1750 m. Valley glaciers and permanent snow and ice fields are characteristic of the region at these elevations, and at its southern limit, mineralization is truncated by the East Fork Glacier.The property is entirely above the treeline, and except for areas of moraine cover and talus slopes, outcrop is abundant."

Jan 1, 1995

In most instances, the preferred mining methods in steeply dipping narrow vein deposits are selective methods such as cut and fill or shrinkage. The main advantage of these methods lies in the higher degree of control over dilution that can be achieved. However, where ore body geometry lends itself to it, high yield bulk methods can also be attractive. Higher productivity (and the associated lower costs) and lower worker exposure are some of the significant advantages that have made such methods so popular. The Lapa gold mine located in North-Western Quebec uses the long hole mining method (with cemented rock fill) very successfully despite challenging ground conditions. This paper focuses on the experience of the mine with regards to drilling and blasting practices. Firstly, the reasons that prompted the selection of this mining method at Lapa are examined. Secondly, the challenges that the difficult ground conditions found at Lapa pose to drilling and blasting are discussed. Finally, the results of trials of different drilling and blasting strategies that were performed at the mine are presented with particular emphasis on the lessons learned.

Aug 1, 2013

By Alla D. Mah

Energies of combustion of vanadium nitride (VN) and vanadium carbide (VC) were measured. Correcting to vanadium tetroxide (V204) as the final state, the heats of combustion were ?H298.15=-118,700±100 cal/mole of vanadium nitride and ?H298.15=-240,270±360 cal/mole of vanadium carbide. With vanadium pentoxide (V205) as the final state, the heats of combustion were ?H298.15= -133.440±100 cal/mole of vanadium nitride and ?H298.15=-255,020±360 cal/mole of vanadium carbide. Combining these results with vanadium oxide data, the heats of formation obtained were ?298.15=-51,880±200 cal/mole of vanadium nitride and ?H298.15=-24,350±400 cal/mole of vanadium carbide. Heats and free energies of formation of vanadium nitride and carbide were calculated to 2,000° K.

Jan 1, 1963

By Perry G. Cotter

The objective of this investigation was to synthesize and investigate the properties of a high-temperature refractory material based on a combination of boron, silica, and magnesium. A magnesium-thermic reaction was used for the synthesis. X-ray examination of the product indicates that the crystalline portion of the composition is a combination of magnesium borides, magnesium silicate, and magnesium orthoborate. Chemical analysis of a representative sample shows, in weight-percent, boron 17.6, silicon 23.9, magnesium 17.8, and chromium 0.5. The balance is largely oxygen. The composition is resistant to high temperatures under oxidizing conditions and is stable in water, hydrochloric acid, and hydrogen. It has a low density (less than 3 grams per cubic centimeter) and a hardness value in the range of quartz. It has a melting point above 1,700° C. and can be hot-pressed to shape in the temperature range between 1,200° and 1,350° C. The properties described in this paper indicate that the material may have some uses as a high-temperature refractory, and because of its boron content it may have some value as a thermal-neutron-absorption material.

Jan 1, 1961

By S. K. Utimurd, D. C. R. Espinosa, J. A. S. Tenório

"Waste Electrical and Electronic Equipment (WEEE) has become an environmental issue due to technological advance and waste plastic is one of the main polluters. The excessive discard of these plastics result in a difficult to dispose it to landfill and need further separation with technique in order to produce high added value plastics. There are many kinds of plastics in extensive use at the present time and the co=on are the acrylonitrile-butadiene-styrene (ABS) and high impact polystyrene (HIPS) used in the production of electric appliances. These plastics are difficult to separate because they have similar densities. Flotation of plastics is one possible separation technique and using selective wetting agents. The separation may be possible given close control at particle size and the concentration of the reagent. The process was able to produce a concentrate of HIPS with at least of 93% purity and a concentrate of ABS with 99% purity.IntroductionThe current situation of municipal solid waste (MSW) management especially in emerging economies like Brazil, the growing population and economic activity will result in a significant increase in the generation of waste in the coming decades. It is worthwhile to review and update the sources, amounts and recovery technologies of specific materials from waste, particularly from municipal solid waste (MSW).The growing impact of the current waste management practices stresses the need for a change in how waste is handled. The 2012 survey and the Brazilian Association of Public Cleaning and Special Waste Disposal Companies (ABRELPE) reports the generation of 62 Mt urban MSW in that year, which is an increase of 13% compared to 2011. It has been reported that in Brazil about 90.17% of the generated MSW is currently collected, which indicates an increase in the coverage of collection services compared to 2011 [ l]."

Jan 1, 2014

By Rodríguez V. Raymundo E.

El presente trabajo describe la evaluación del uso de brocas tricónicas como herramientas principales de perforación en el yacimiento minero de Cerro Verde, Arequipa. La óptima utilización de esta herramienta representa el 30% de los costos totales de perforación, los cuales se ven reflejados en los factores de análisis a considerar para la superación de performances y las perspectivas que se aplicarán en el futuro para alcanzar mejores rendimientos y bajar los costos de perforación.

Oct 14, 1980

By G. L. Fredrickson, T. A. Johnson, B. R. Westphal, J. C. Wass, S. X. Li, D. Vaden

"Recovery of uranium from the Mk-IV and Mk-V electrorefiner vessels containing a LiCl/KCl eutectic salt has been on-going during the pyrometallurgical processing of used nuclear fuel for 14 and 12 years, respectively. Although austenitic stainless steels are typically utilized for LiCl/KCl salt systems, the presence of cadmium in the Mk-IV electrorefiner dictates an alternate material. A 2.25Cr-1Mo alloy (ASME SA-387) was chosen due to the absence of nickel in the alloy which has a considerable solubility in cadmium. Using the transition metal impurities (iron, chromium, nickel, molybdenum, and manganese) in the electrorefined uranium products, an algorithm was developed to derive values for the contribution of the transition metals from the various input sources. Weight loss and corrosion rate data for the Mk-V electrorefiner vessel were then generated based on the transition metal impurities in the uranium products. To date, the corrosion rate of the 2.25Cr-1Mo alloy in LiCl/KCl eutectic is ""outstanding"" assuming uniform (i.e. non-localized) conditions.IntroductionLow-enriched uranium products are being recovered from the Experimental Breeder Reactor-II (EBR-II) and Fast Flux Test Facility (FFTF) used nuclear fuels by a pyrometallurgical treatment process at the Idaho National Laboratory (INL). The treatment process comprises a set of operations designed to neutralize bond sodium, recover uranium from radioactive fission products, and place the fission products into acceptable waste forms [1-2]. Reactive sodium metal, essential for heat transfer purposes during reactor operations, is readily converted to chloride during the process. Electrorefined uranium products are currently being stored pending a final disposition decision. Treatment of the EBR-II used driver fuel was initiated in June 1996 while blanket fuel processing started in September 1998. These treatment processes continue on the balance of the used fuels."

Jan 1, 2011

By James S. Browning

The Bureau of Mines conducted laboratory batch and small-scale continuous flotation tests of weathered mica pegmatite ores from Alabama and North Carolina to determine the technical feasibility of recovering commercial-grade mica concentrates. A new anionic-catonic method was developed for recovering mica in the presence of clay slimes. In continuous tests, concentrates containing 98.1 percent mica were obtained from the Alabama pegmatite ore; the North Carolina pegmatite ore concentrates contained 97.2 percent mica. The recoveries were 83.8 and 81.6 percent, respectively.

Jan 1, 1965

By Xi-chang Shi, Yun-feng Fu, Bai-zhen Chen, Hui Xu, Xiang Xiao

"Extracting boric acid from saline brine by boron specific ion-exchange resin was investigated. Effects of resin amount, temperature, time and stirring speed on boron adsorption rate were studied in the experiments. The results indicated that the XSC-700 resin showed excellent boron absorbability and it performed better property for elution. The maximum boron adsorption capacity was 6.16 mg/ml in the optimum conditions: the resin concentration of 5 ml/(100 ml brine), the temperature of 60°C, the time of 5-6h and the stirring speed of 100 r/min. Boron was eluted from the resin with HCl and boric acid was crystallized by evaporating the eluate. The product of boric acid was in pure form as confirmed by XRD and other analysis techniques.1 IntroductionBoron has a number of minerals in nature such as tincal, colemanite, ulexite, and kemite, etc. [1-2]. Boron and its compounds are chemical materials of significant value. The principal industrial uses of boron compounds are in the production of glass, porcelain, enamels and detergents. Other uses include fertilizers, metallurgy, and nuclear shielding [3-4]. In recent years, because of the large-scale mining boron ore, ore resources are drained gradually. With the development of science and technology, the boron mineral resources will be unsatisfied with the future requirement. There exits abundant boron resources in salt lakes which cover about 40% of the total reserves in China. If we can obtain boron from salt lakes, it will produce great economic interests [5-6]. Therefore, actively seeking boron from salt lake and other resources in suitable conditions has become a hot spot in the research organizations of boron resources development and utilization in the world [7].There are many methods such as acid crystallization, solvent extraction and ion exchange processes suggested effective for boron extraction from aqueous solutions. Acid crystallization method has the shortcomings of complicated procedures, the pollution caused by hydrochloric and other ingredients returning to salt lakes during the extraction process. Although solvent extraction process increases the boron acid recovery efficiency, the cost of production is high [8-9]. However, Chelating resin extracting boron has the characteristics of simple process, easy operation and no pollution. It was reported that chelating resins containing functional groups show a high selectivity for boron extraction [10-12]. Therefore, ion exchange technique which is now the most practical application of significance and most extensively used ha"

Jan 1, 2011

By Guo Chen, Jin Chen, Jinhui Peng

"In this paper, the methods of life cycle assessment for microwave hot air systems, and the concept of green degree were proposed. Greenness evaluation index, evaluation system and evaluation model of microwave hot air systems were established. Also, life cycle assessment processing based on these ideas was introduced. Analytic hierarchy process and fuzzy decision- making method were utilized to establish and solve the greenness evaluation of assessment model, while the scores of green degree in microwave hot air systems were obtained. The results show that Life cycle assessment can be applied effectively and efficiently to the microwave hot air systems.IntroductionHot air systems are an important industrial operation condition, which is used to provide high temperature air for materials processing. Nowadays, high temperature airs are manufactured by the conventional heating processes, in which some ceramic materials are used as heating materials. However, these processes pollute the environment. Therefore, to explore new method to produce high temperature air with low energy consumption and less environment pollution are necessary.Microwaves are now being used in various technological and scientific fields in order to heat dielectric materials [1]. Microwaves irradiation has been explored in materials processing in recent years [2-3]. The main advantage of using microwave heating is that the treatment time can be considerably reduced, which in many cases represents a reduction in the energy consumption as well. Since there is energy absorption but no heat conduction, the heating is very rapid and highly efficient, resulting in energy savings and the shortened processing time [2, 4]. Compared with conventional heating techniques, the additional advantage of using microwave irradiation is that microwave irradiation achieves both internal and uniform heating [5-7]. In addition, it is more convenient to control the microwave irradiation processing, because of no direct contact between the heating source and heated materials with less equipment size and waste [2, 8-9]. Life cycle assessment is used and accepted methods for the evaluation of the environmental impacts of products or systems [10]. Recently, many appropriate evaluation methods have been developed for life cycle assessment [11-12]. These proposed methods usually are employed for the evaluating product and analyzing results [13]. Among them, the analytic hierarchy process and the fuzzy comprehensive evaluation stand out as a popular method utilized in many fields [14-16]. Analytic hierarchy process and fuzzy comprehensive evaluation are a combination of mathematical and statistical technique that is useful for analyzing the effects of several independent assessment aspects on the system goal without the need of the predetermined relationship between the objective function and the assessment aspects [17-19]."

Jan 1, 2013

By R. C. Diehl

Coal, fly ash, and flue gas samples were analyzed for mercury (Hg) by double gold amalgamation-flameless atomic absorption spectrophotometry. The purpose of the study was to elucidate the fate of the trace mercury in the coal when the coal is burned. Samples were collected from a bench-scale 100-g/hr combustor, a 500-lb/hr combustor, and three coal-burning powerplants. In all cases mercury was found in the fly ash. The amounts ranged from about 9 to about 70 percent of the mercury in the coal that was burned.

Jan 1, 1972