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By W. Graham

"IntroductionEFFLORESCENCE is herein considered to be any deposit of salts on the surface of a masonry structure that is brought from within or through the structure by capillarity and deposited by evaporation. Usually, efflorescence is white although green, yellow, and brown efflorescence is sometimes observed.The common white efflorescence almost always consists of sulphates of the alkali and alkaline earth metals and calcium carbonate, although sodium chloride is frequently present in structures erected near the sea shore.The first and most obvious result of the presence of soluble salts in masonry is the unsightly accumulation of these salts on the surface. This is particularly noticeable early in its life and is frequently fugitive ( 1), as much of the salt is soluble and is gradually washed away by rain. This removal can usually be facilitated by scrubbing; the structure with dilute hydrochloric acid.A more serious effect is the continuous accumulation of soluble salts as a result of ingress of sulphur acids in rain water or water from the ground. This may eventually cause spalling and disintegration by crystallization of salts in the pores of brick and mortar. An example of this type of failure, resulting from the crystallization of calcium sulphate, is discussed by Hardesty (2). Butterworth (3) describes similar failure resulting from •crystallization of magnesium sulphate."

Jan 1, 1954

By M. Jele

? Sulphuric acid plant in umbogintwini. ? Double absorption plant, capacity of 550MTPD. ? Build by simon curve during the year 1973. ? Side stream plants such as: ? Liquid SO2 Plant, ? Liquid SO3 and ? Oleum plant

Jan 1, 2009

By S. Subhawong

Following the startup of the zinc plant in Clarksville, Tennessee, in 1978, the original effluent treatment plant did not perform as designed. The sludge, produced in a conventional lime neutralization treatment, settled poorly and began to fill the permitted lined impoundment within two years, well short of the original design capacity. Another sludge pond had to be constructed. This led to a new process modification of the original design. Although the design is still based on the conventional lime precipitation of heavy metals, the current effluent treatment plant has evolved into a hydrometallurgical circuit, capable of producing good quality water without generating sludge. Undesirable elements are bled from the zinc circuit and are rejected through the effluent treatment operations. Wallboard grade gypsum is produced, instead of sludge, and all the gypsum is sold to cement and wallboard plants. This operation also recovers and returns more than 1,500 tonnes of zinc annually to the 105,000 tonne/y zinc plant.

Jan 1, 2000

By A. N. Veltmeyer

"INTRODUCTIONTeck-Corona Operating Corporation's David Bell Mine is located 35 Km east of Marathon, Ontario. In conjunction with its 1000 tonne per day gold concentrator, the company operates an effluent treatment plant for the treatment of mill, mine and site effluents prior to environmental discharge. This paper provides a brief overview of treatment strategies and methods, employed to detoxify final effluent.WATER MANAGEMENTThe tailings impoundment basin, located 3 Km south of the plant site, provides storage capacity for all process effluents and site run-off. Basin supernatant (reclaim water) is recirculated to the plant for reuse as process water, in order to minimize fresh water consumption. As site run-off and limited fresh water intake exceed natural losses due to evaporation, reclaim water in excess of process requirements is passed through the effluent treatment (ET) facility to control tailings basin level by providing regulated discharge of environmentally acceptable effluent. (Figure 1)PASSIVE TREATMENTTo reduce treatment costs and burden on the ET facility, reclaim water is fed to the plant to take maximum advantage of natural destruction processes occurring in the tailings basin.These include: volatilizationphotodecompositionbiological oxidation and precipitationstorm water dilutionConcentrator recovery techniques (Figure 2) are directed toward maximizing gold recovery while limiting the addition and extraction of contaminants requiring disposal and eventual treatment.Currently ore ground to 90% -200 mesh is pre-aerated at pH 9.0 with lime for 18 hours prior to 30 hours cyanidation at pH 9.5 with low cyanide ion excess (70 ppm).Pre-aeration passivates cyanicides prior to cyanide contact. This reduces cyanide consumption and the formation of cyanide complexes. In conjunction with recovery requirements low pH is maintained to retard the dissolution of stibnite into its antimony and sulfide components."

Jan 1, 1989

By Plamer D. J, Newman O. M G

The Effluent Treatment System at Pasminco Metals - EZ (PMEZ) was commissioned in December, 1991 and has operated satisfactorily, ensuring that aqueous discharges from PMEZ comply with the Tasmanian Environment Protection Act. The system treats both spills and run-off from the Zinc Plant, and acidic liquor generated in the gas cleaning section of the Sulphuric Acid Plant. The spills and run-off from the Zinc Plant are collected in a large catchment pond. The pond liquor, after partial neutralisation with sodium hydroxide to pH 4, and removal of suspended solids, is preferentially recycled to the Zinc Plant, for example, for washing of residues. Liquor which cannot be recycled, is treated in the Lime Neutralisation Section. The other input to the Lime Neutralisation Section is the acidic liquor from the Sulphuric Acid Plant from which mercury has been removed by contact with aluminium pellets in a fluidised column. In the Lime Neutralisation Section, the liquors are blended and neutralised to pH 10 by the addition of slaked lime. The heavy metals and most of the fluorine are precipitated. The precipitated solids are removed in a thickener with part of the thickener underflow being filtered. Most of the thickener underflow is recycled to generate solids that settle rapidly and filter well. The filter cake is returned to the Zinc Plant for the recovery of contained heavy metals while the thickener overflow is discharged to the Derwent River.

Jan 1, 1993

By Trevor Yeomans, David Yaschyshyn

"Placer Dome (CLA) operates the 90-year-old Dome Mine, in South Porcupine, Ontario.The milling operation currently processes 5 million tons of ore per year, from both the underground and Open pit mining operations, producing 320 000 ounces. The milling process is conventional crushing and grinding, with gold recovery by gravity followed by leach/CIP.Cyanide tailings are impounded in a large (325 ha) tailings area where cyanide is allowed to degrade naturally. Effluent is discharged seasonally during the summer and early fall months to maintain site water balance. Pond water is reclaimed for sole use within the mill process.In 1995, an Effluent Treatment Plant (ETP) was constructed for the purpose of removing dissolved metals and suspended solids. In 1997, an INCO S02/Air cyanide destruction module was added.During this time period, the treated effluent often failed toxicity tests required by the Ontario MISA Regulation, even though effluent chemical parameters were below permit limits. Two studies identified ammonia as the toxicant to Rainbow Trout, and free copper as the toxicant to Daphnia magna.From a literature study, and contacts within the Ontario Mining Association, the use of chelation as a final end of pipe treatment step to render any remaining free copper and metal fractions biologically unavailable was considered. Lab and plant scale tests followed.During the 1999 ETP operating season, the addition of the chelant EDTA (ethylene-diamine-tetraacetic-acid) commenced. To date discharged effluent has passed all toxicity tests.The paper will review the effluent treatment history, current effluent treatment plant operation, and detail the use of EDTA for successful toxicity control.History of Tailings Deposition, and Effluent Treatment From 1910 to 1995Over it’s ninety years of operation, the Dome Mine milling circuit has changed from the original 1910 stamp-mill mercury plant, to today’s modem 14 000 ton per day automated gravity and Carbon in Pulp based plant.By the 19803, a modern mill was operating on mainly underground mined ore. The plant was operating at some 3 800 tons per day, using fairly conventional processing routes.The number 4 tailings dam was being used for tailing’s deposition.All effluent treatment was by natural degradation of cyanide. Discharge was from decanting type structures during the summer months only, maximizing the use of natural degradation no tailings effluent was recycled for Mill use."

Jan 1, 2001

By Irajá Bernardino Ribeiro Juniorr

O presente trabalho tem por objetivo apresentar alguns exemplos de aplicações na Indústria Siderúrgica e de Mineração (Prensa de Rolos e Torre de Resfriamento) mostrando que com o emprego de uma confiável metodologia para determinação dos benefícios energéticos é possível a implantação das medidas de conservação de energia em sistemas de força motriz instalados nestas indústrias com o simples uso de Lubrificantes Sintéticos Especiais em substituição ao largo emprego de óleos minerais. Esta solução também proporciona ganhos energéticos e financeiros expressivos e mais atrativos do que as já consagradas soluções de eficiência energética como troca de lâmpadas e /ou motores de alto rendimento. Além do mais, a troca de lubrificante já é rotina implementada nas indústrias e seus profissionais da área de manutenção, não sendo preciso treinamento adicional para implementação, tornando esta ação com o propósito de economizar energia simples e fácil de ser implementada. Este trabalho é uma parte dos resultados do projeto inovador desenvolvido pela Klüber Lubrication desde 2010, onde o principal objetivo é disponibilizar aos usuários de sua linha de produtos este recurso, internacionalmente reconhecido, de Medição & Verificação para a comprovação de ganhos de energia em prensas de rolos com alcance de redução de cerca de 10% de consumo de energia.

Aug 17, 2017

By David Fernando de Carvalho

Este estudo de caso foi solicitado por uma grande mineradora brasileira à Chemtech Engenharia, com o objetivo de avaliar um projeto de um Transportador de Correia de Longa Distância na fase conceitual, onde se buscava a otimização do consumo energético, mínimo investimento financeiro inicial e redução dos custos operacionais. O resultado deste estudo de caso foi usado como diretriz no projeto básico do equipamento, além de ser usado como referência para outros projetos similares.

Sep 25, 2017

By Yuri Oliveira Lima, Vitor Furlan de Oliveira, Adriano Gomes de Freitas, Ricardo Borges dos Santos, Luis Alberto Martinez Riascos

O presente trabalho, resultante da parceria público-privada entre a empresa Zeppelin Systems Latin America e a Universidade Federal do ABC, tem por objetivo validar o desempenho em termos de taxa de transporte e consumo energético de um vaso de pressão não convencional, o equipamento atua como alimentador de sólidos industrial para transporte pneumático, desenvolvido para operação de transporte de materiais em fase densa. Calcário é usado como material de deslocamento durante os ensaios no Centro de Testes da empresa, foi verificado que o novo injetor pressurizado tem menores dimensões e complexidade de operação, e possui taxa de transporte e consumo específico efetivo equiparáveis às versões de vasos de pressão convencional.

Aug 1, 2019

By E. Yan

Electrostatic separation has been a mainstay of minerals sands flowsheets for over 50 years. Recent electrostatic developments have shown better conductor/non-conductor separation than technology previously available. Results to date show significantly increased separation efficiency over prior-art high-tension roll electrostatic separator (HTR). These improvements allow greater simplification of MSP circuits by minimizing re-circulating loads. The distinct features of the eForce include: 1) A provision that minimizes the affects of particle size to improve separator performance, 2) an enhancement of the design and arrangement of the static electrode providing a greater attraction force for separating fine conductive particles, and 3) inner roll and outer plate electrode configuration to improve separation efficiency and throughput capacity. Key Words: eForce, Electrostatic, Ion bombardment, HTR, Separation Efficiency, Electrostatic Classifier

Jan 1, 2003

By Armando Vazquez

When water enters the EAF, some chemically dissociates to H2 while some remains as H2O vapor. Depending on operating conditions the levels of combustible gases (CO and H2) and H2O are continually changing throughout the course of any individual heat and on a heat-toheat basis. The EFSOP® system has been implemented in more than 80 installations as a powerful tool to reduce furnace operation costs but with water detection technology the off gas technology is a valuable solution to improve safety. This paper describes the latest results when using Tenova Goodfellow’s new standalone water detection technology that for the first time provides real-time analysis of both H2O vapor and H2 from start-to-end of a heat. It involves a newly designed water cooled probe and heated line that eliminates condensation during off-gas sampling and an analyzer equipped with a proprietary system for analyzing both H2O vapor and H2.

Jul 30, 2018

By Lars Richter, Franz-Werner Gerressen

"The Eglinton Crosstown Line was conceived as the Eglinton Crosstown LRT, a partially underground light rail line, announced in 2007 as part of the Transit City plan, which included the implementation of six other light rail lines across Toronto.There were 43 stops planned for the Eglinton Crosstown LRT, 13 of which would be underground . For those underground stations a lot of specialty foundation works needed to be carried out. King piles, soldier piles with lagging and secant piles were mainly required fulfilling the tasks of installing the retaining wall system.The paper will focus on the original design and alternative solutions, discussing the benefits and limits of these. It will also explain the installation process in general as well as some specific features related to specific site conditions, e.g. limits in installation depth, soil characteristics etc. The required equipment will be explained showing the benefits and limits.INTRODUCTIONThe Eglinton Crosstown project is a 19-kilometre LRT line that will bring much needed relief to the transit woes of Torontonians. Traversing the city in an east-west slice across the midtown artery of Eglinton Avenue, the Crosstown rail line involves a combination of 15 underground stations and 10 atgrade surface stops. It is one of the largest transit infrastructure projects under way in North America today. Aecon has joined partners ACS Infrastructure Canada, Ellis Don, and SNC-Lavalin to form Crosslinx Transit Solutions (Crosslinx).As with many of today’s mega public transportation projects, the Crosstown LRT follows the Public- Private Partnership (P3) model. Aecon is an equal partner in the $5.3-billion Crosslinx consortium to develop the Eglinton Crosstown LRT project in Toronto. Upon the LRT's completion in 2021, Metrolinx, the region’s transit authority and also the project client/owner, will turn to the Toronto Transit Commission (TTC) to operate it. The impact of this highly anticipated LRT line on commuters in the Greater Toronto Area (GTA) is expected to be dramatic and immediate once the first train leaves the station five years from now. In fact, Metrolinx is estimating that within its first 10 years of service, the Crosstown line will be carrying 5,500 passengers per hour (in peak direction) and making 100 million passenger trips annually."

Jan 1, 2017

By G. Aggistalis, N. Kazilis, C. Rawlings, N. Rachaniotis, S. Raptopoulos, M. Knights, R. Game

The Egnatia Odos (Odos meaning road) is one of Greece’s largest ever highway construction projects and one of Europe’s most important. The Highway will assist in the connection of the Greek Ionian/Adriatic Coast with Turkey and the Black Sea reviving an historic Roman alignment “Via Egnatia” connecting Rome to Constantinople (now Istanbul). There are 74 twin tunnels (60 bored and 14 cut-and-cover) with lengths ranging from 160 m (175 yd) to 4,600 m (5,031 yd) and 100 m (109 yd) to 270 m (295 yd),respectively. The complex geology and resulting physical geography have had a major influence on both the design and construction of these tunnels. This paper describes the management, design and construction challenges of these numerous tunnels.

Jan 1, 2005

By Ahmed M. Nofal

This article reviews some important characteristics of the known Egyptian phosphate deposits, such as mining conditions, transport criteria, quality of products affecting their export markets and utilisation in fertilizers industry. Special attention will be given to the newly discovered large deposit of Abu-Tartur with some billion tons of ore reserves. A big project is now under implementation on Abu-Tartur deposit where the long-wall method of underground mining will be applied and a flow sheet of beneficiation will be in operation including a particular feature nontraditional in phosphate processing: high-intensity magnetic separation to eliminate dolomite impurities. Comparison with some international phosphates will be tried in order to trace the situation of Egyptian phosphates in the world market.

Jan 1, 1993

By John A. Hansuld

Geochemical dispersion of metals under various environmental conditions is discussed within the frame-work of Eh (oxidation potential) and pH (acidity). In general, two aspects are considered -(1) the oxidation of certain primary sulphides in the outcrop or sub-outcrop environment, and (2) the movement of metals in different dispersion media. Practical applications of each are illustrated by means of exploration case histories representing environmental conditions in the Canadian Shield, the southwestern United States and the Caribbean.

Jan 1, 1966

By Munro P. D

Eh-pH measurements were taken on an industrial zinc reverse flotation process at Brunswick Mining and Smelting Corporation Limited. Laboratory zinc reverse flotation testwork on samples of the feed to the industrial process produced Eh-pH data which were similar to the data from the industrial process.Later, the Eh-pH data from the industrial process were compared with data from a pilot plant scale zinc reverse flotation process at Mount Isa Mines Limited. After comparison with the data from Brunswick Mining and Smelting Corporation, deficiencies in the pilot plant Eh-pH data could be recognised and corrective actions were taken for the pilot plant. A robust pilot plant zinc reverse flotation process was obtained with consistent performance at the expected level.The implications of these findings for a range of processes are also discussed.

Jan 1, 1988

By K. A. Natarajan, I. Iwasaki

With a platinum electrode the Eh-pH response in aqueous systems follows an empirical relation [Eh = E- 0.059 pH](1) where E usually carries a value between 0.8 and 0.9 v. The same potential (E) is observed with a number of other noble metal electrodes in the absence of surface poisoning and of other well-defined redox couples. Many sulfide mineral electrodes also respond in a similar manner in solutions containing their respective ions over wide pH ranges, especially in the alkaline pH region. Such a parallelism between noble metal and sulfide mineral electrodes points to certain implications of their surface conditions, and the flotation and leaching behaviors of sulfide minerals under aerated conditions may be inferred with respect to the foregoing Eh-pH response. Comparison of Sulfide Mineral and Noble Metal Electrodes [Fig. 1] shows the Eh-pH response of pyrite, galena, chalcocite, and pyrrhotite electrodes, reported by Sato, and some experimental points obtained with a platinum electrode in distilled water. [Eq. 1] is seen to be followed by all these electrodes. It is interesting to note that the response of the pyrite electrode as shown is identical to

Jan 1, 1973

By John L. Stauffer, Allan Lipton, Kim Leitzel, Lesley Gaydos, Laurence M. Demers, Douglas C. Kuhn

Eicosanoids and cytokines produced by the alveolar macrophage (AM) are key mediators of pulmonary inflammation and fibrosis resulting from occupational exposure to mineral dust. In order to determine if eicosanoid and cytokine production are altered by chronic inhalation of coal dust, we compared the production of prostaglandin E2 (PGE2), thromboxane A2 (TxA2), leukotriene B4 (LTB4), interleukin 1 (IL-1), tumor necrosis factor (TNF) and platelet-derived growth factor (PDGF) by cultured AM from non-smoking normal human volunteers and coal miners. Inhibitors of eicosanoid biosynthesis were administered to AM from coal miners in order to determine if a link between eicosanoid and cytokine production exists in these cells. Basal PGE2, TxA2, TNF and IL-1 production by AM from active miners was increased compared to AM from normal volunteers. However, the production of these eicosanoids and cytokines by AM from former coal miners was reduced compared to control AM. Administration of the cyclooxygenase inhibitor, suprofen, and the lipoxygenase inhibitor, nordihydroguaiaretic acid, reduced PGE2 and TxA2 production in miners' AM but had no effect on LTB4, IL-1 or PDGF production. Specific inhibition of thromboxane synthase by UK38,485 was associated with a significant reduction in TNF production in active miners' AM but had no effect on PGE2, LTB4 or IL-1 production. The prostacyclin analogue ZK96,480 also specifically inhibited TxA2 production in active miners' AM. The results of these studies suggest that coal dust exposure is associated with alterations in AM eicosanoid and cytokine production which may be relevant to the development of pulmonary inflammation and fibrosis. In addition, the lack of effect of inhibitors of PGE2 biosynthesis on IL1 production in miners' AM suggests the production of these intercellular messengers may not be linked in AM chronically exposed to coal dust.

Jan 1, 1991

By J. L. Stauffer, L. Gaydos, L. M. Demers, D. C. Kuhn

"Eicosanoids and cylokines produced by the pulmonary alveolar macrophage (PAM) are key mediators for the defensive role this cell plays in neutralizing the inhalation of particulate dusts and foreign microbes. However, these factors are also mediators of inflammation and their uncontrolled release may cause the lung injury and liorotic changes observed in individuals exposed occupationally to mineral dust. In vitro studies have suggested a link between the production of certain eicosanoids and cylokines released from the activated PAM. To this end, we have studied the release of eicosanoids (PGE2, TXB2 and LTB4) and cylokines (IL-1 and TNF) by cultured PAM, obtained from healthy human volunteers by bronchoalveolar lavage under basal culture conditions and following acute exposure to provocative agents such as the endotoxin lipopolysaccharide (LPS) and mineral dusts including silica. Studies were also carried out in the presence of specific cyclooxygenase inhibitors. The addition of LPS (10 µg/ml) to the culture medium produced a significant increase in PAM release of the eicosanoids: PGE2 (3.5 fold over baseline), TXB2 (2.8 fold over baseline) and LTB4 (4 fold over baseline). LPS also elicited a 2.5 fold elevation in IL-1 from these cells and a 9 fold increase in TNF release. The cyclooxygenase inhibitor, ibuprofen, significantly inhibited the LPS-induced rise in PGE2, TXB2 and TNF but had only a modest suppressive effect on IL-1 release. Exposure of these cells to silica dust elicited a similar augmentation in eicosanoid and cylokine release which was neutralized by prior exposure of the cells to ibuprofen. These results suggest that the enhanced production of eicosanoids and cytokines by PAM exposed to endotoxins and/or mineral dusts may be linked and that inhibition of eicosanoid release is linked to the production of TNF. IL-1 release however is not effectively neutralized by cyclooxygenase inhibition.INTRODUCTIONThe initial pulmonary cellular response to inhaled mineral dust involves the elaboration of potent inflammatory mediators from the pulmonary alveolar macrophage (1). These mediators include the eicosanoids (oxygenated metabolites of arachidonic acid) and cytokines (intercellular peptides) which are released into the alveolar space by the interaction of mineral dust with the PAM surface membrane. The eicosanoids and cytokines promote local nonvascular and vascular smooth muscle contractility changes, elicit the recruitment of additional mononuclear cells into the alveolar space, and enhance the activation, growth and differentiation of lung fibroblasts (2). In this study we sought to examine whether eicosanoid release and metabolism are linked to cytokine release when PAM are activated upon exposure to endotoxin or mineral dusts. Modulation of these pathways through inhibitory pharmaceutical agents may help attenuate the Injurious effects caused by a sustained release of these proinftammatory intercellular factors (3). To that end, we have studied the in vitro effects of endotoxin and silica on eicosanoid and cytokine release from cultured PAM obtained from healthy human volunteers."

Mar 1, 1992

By Laurence M. Demers, Douglas C. Kuhn

It has been suggested that radicals on the surface of dust particles are key chemical factors in the pathophysiology which results from the occupational inhalation of coal and silica dust. In addition, oxygenated derivatives of arachidonic acid (eicosanoids) have been implicated as important biochemical mediators of mineral dust-induced lung disease through their role in bronchial and vascular smooth muscle reactivity, inflammation, and fibrosis. Therefore, we assessed eicosanoid production by the rat alveolar macrophage (AM) exposed in vitro to mineral dusts with varying surface chemical characteristics in order to determine if radicals associated with the mineral dub1 could influence the production of pro-inflammatory mediators in the lung environment. Rat AM were exposed to freshly fractured or "stale" bituminous coal dust, as well as untreated silica or silica calcined to 500°C and 1100°C. Prostaglandin E2 (PGE2) and thromboxane B2 (TxB2) levels in incubation medium were determined by specific radioimmunoassay. When AM were exposed to freshly fractured coal dust, PGE2 and TxB2 production were markedly increased. In contrast, exposure of AM to "stale" dust significantly reduced PGE2 and TxB2 production. In vitro exposure of AM to untreated silica resulted in a significant increase in PGE2 and TxB2 production compared to control. However, exposure of AM to silica calcined to 1100°C resulted in eicosanoid levels which were not significantly different from control. These findings suggest that radicals associated with respirable coal and silica particles may play a key role in the ability of mineral dust to activate AM eicosanoid production.

Jan 1, 1991