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The SART (sulfidisation, acidification, recycle, and thickening) process is an effective way to separate copper and cyanide from each other in the waste stream of gold processing plants using cyanidation. Factorial experimentation has been conducted to create models of copper recovery, cyanide recovery, acid addition, and oxidation I reduction potential during SART. Economic analysis of the resultant models showed that SART is best operated with a sulfide to copper molar ratio of around 0.56, a pH of 4, and a minimised cyanide to copper molar ratio. The experiments also showed that thickening time may have drastic impacts on SART performance.

Jan 1, 2011

By L. Janku, G. Hancox, M. Villenueve, C. Massey

Wellington lies in a seismically active area 150 km from a subduction zone and in the vicinity of several active faults, which poses a risk to its infrastructure and inhabitants. One of these major faults, the Wellington Fault, runs through the centre of the city and across several lifelines, including the natural gas pipeline and the freshwater pipeline. The first settlement in the area was severely damaged in 1848, soon after its establishment, by an earthquake of approximate magnitude Mw 7.4 - 7.5 (Grapes, Little, & Downes, 1998). In 1855, another earthquake of magnitude Mw 8.2 generated by a nearby fault uplifted the eastern part of the current Wellington area and caused several landslides in the surrounding hills (Grapes & Downes, 1997). The Central Business District lies in the area of a sedimentary basin and partly on reclaimed land. Many residential areas, as well as some vital infrastructure, however, lie on or along the slopes in the surrounding hills. The bedrock in the area comprises predominantly the Torlesse greywacke of Permian – Late Triassic age. The greywacke is tilted to a steep angle, intensively faulted and fractured (Cook, 2001). Even though several studies in the past assessed the seismic risk in the area (e.g. Brabhaharan, Hancox, Perrin, & Dellow, 1994), the studies either focussed solely on the area of the sedimentary basin or based their assessment of the hilly terrain purely on slope morphology (slope angle). Previous studies have shown that slope shape and contrasting materials in the slope can amplify earthquake ground motions, such factors are typically called site effects (e.g. Geli, Bard, & Jullien, 1988). Any attempt to systematically quantify the site effects and consequent seismic response of the slopes and use it to predict the consequences of the next large-magnitude earthquake, has not yet been carried out. In this extended abstract we outline the methodology of a PhD research project, focussed on investigating the site effects on the slopes around Wellington and on creating representative numerical models of ‘characteristic’ Wellington slopes and materials. This extended abstract presents the methodology adopted for the assessment using the Te Ahumairangi Hill site as an example.

Jan 1, 2015

By D. Runnels, Daniel Roy, Ricardo Esteban, J. Torrealba-Vargas

"An intuitive way to reduce power consumption in grinding operations is to feed the grinding circuit with finer feed by enhancing blasting and fragmentation control. The optimization of blasting with the objective of minimizing power consumption in grinding is not new.The study was based on a Canadian mine that processes a very hard ore. BBA conducted blasting/fragmentation and grinding circuit surveys in 2014. The results of the exercise were used to develop a base case model to simulate the effect of blasting in the operation on the grinding circuit. Tools for fragmentation simulations, particle size measurement and crushing/grinding simulations were used with the objective of reducing the OPEX costs including power consumption.The paper describes the steps involved in the model optimization as well as an economical evaluation of the OPEX savings.INTRODUCTIONIn 2014 BBA was retained by one of its clients to conduct a crushing and grinding survey. The objective of the survey was to update the grinding circuit model with production data and also to develop a tool to investigate opportunities for process improvement.A second phase of the study involved the development of drilling and blasting and crushing models. The models were used to diagnose the operations and to investigate opportunities for process improvement.The objective of the present study is to describe the approach and to identify potential improvements to overall mine site operating costs by better integrating mining and milling operating costs with blasting and grinding models."

Jan 1, 2016

By M. B. Greyver

The results of laboratory tests on iron precipitation from non-decopperized nickel anolyte are discussed. The parameters (pH, oxygen consumption and stirring speed) for iron precipitation from the anolyte, using the oxygen in the air, were determined. In the experiments conducted under optimized conditions, the residual concentration of iron in the anolyte after precipitation was 0.7-2.7 mg/L, and the copper and nickel losses to the solid phase were 0.05-0.07% and 0.05-0.16%, respectively. The filtration ability of the iron slurry obtained was 2 to 5 times higher as compared to that after chlorine oxidation and oxyhydrolysis. The leaching of the non-ferrous metals from the iron cake made using the separate nickel anolyte purification process was possible by dissolution in sulphuric acid. It was established that after cobalt precipitation from the copper- and iron-depleted anolyte, the precipitates obtained had lower ratios of Fe:Co and Ni:Co.

Jan 1, 2006

By N. Sarmady, Mei Li, N. C. Parson, W. J. Poole

"The mechanical behaviour of AA6082 is a function of the extrusion conditions and in particular, the quench rate after extrusion. It is well known that precipitation of Mg-Si phases on grain boundaries during quenching can negatively affect the ductility of the alloy. In this study, AA6082 alloys containing 0.5 wt. % Mn and 0.15 wt. % Cr were direct chill (DC) cast, homogenized and then extruded to produce 3 mm x 42 mm strips. The microstructure in the as-extruded strips was unrecrystallized due to the Zener-Smith drag from the Mn/Cr dispersoids. It was shown that a solution treatment of 5 minutes at 560°C did not significantly affecting the as-extruded microstructure but if the as-extruded strip was cold rolled prior to heating, recrystallization occurred concurrently with the solution treatment. As such, 3 initial microstructures were produced, i.e. unrecrystallized and recrystallized with a grain size of 9 and 40 µm. After the solution treatment, controlled cooling experiments were conducted using the Gleeble 3500 thermomechanical simulator with cooling rates of 10, 25, 80°C/s as well as water quenched. The mechanical properties (e.g. yield stress, fracture stress and fracture strain) were determined from tensile tests for the different combinations of initial microstructure and cooling rate. The relationship between the quench rate and precipitation of Mg-Si phases on grain boundaries was examined by FEG-SEM. It was found that the yield stress decreased as the cooling rate decreased and that there was complex relationship between the fracture properties and the microstructure.INTRODUCTION As the automotive industry strives to reduce fuel consumption and CO2 emissions with the goal of reducing the environmental impact, there is a need for lighter vehicles. As a result, aluminum alloys are gaining popularity to replace steel parts as structural components. An exemplar of this is the Ford F-150 pickup truck which has an aluminum body and is ˜750 pounds lighter than the previous steel version of the vehicle. The structure includes a mix of aluminum sheet, extrusions and cast alloys. The current research is concerned with the performance of aluminum extrusions in applications such as side rails, crash tubes and other structural parts. These components experience a combination of bending, stretching and folding both during the forming of the part and in service, e.g. crash of a vehicle. There is a need to have detailed information on the influence of processing on final material performance, in particular the cooling rate after extrusion."

Jan 1, 2018

By V. I. Ryaboy, S. A. Kondratyev

"The paper describes influence of desorbed species (DS) of a number of xanthates and higher dialkyldithiophosphates on the collective ability of these reagents. Adsorbed on mineral DS of the reagents in the form of products of non-stoichiometric interaction between xanthates and heavy metal salts can pass to the gas–liquid interface and remove liquid from the layer between mineral particle and water surface. A high-speed video recording displays the process of spreading of DS of xanthates and dialkyldithiophosphates over water at the moment of local rupture of the water layer. Expansion of “dry” spot on the mineral surface after DS of xanthate capture and displace liquid from the layer has been proved with video images. The comparative analysis of collecting ability and dynamic surface activity of dialkyldithiophosphates shows that these characteristics are in good correlation. The forces exerted by spreading film of the reagent’s DS on liquid in the water layer are evaluated, and the water flow rate from the layer is determined. The line of the reduction in thickness of the water layer behind the front of spreading film of DS of dialkyldithiophosphates and xanthates coincides with the line of the increase in their dynamic surface activity. Their force on the liquid volume in the water layer characterizes collecting ability of the DS film of xanthates and dialkyldithiophosphates. It has been supposed that the collecting ability of DS of a reagent is a part of its overall flotation activity, conditioned by surface tension of solution and, thus, defined by the structure of hydrocarbon fragment of the reagent.INTRODUCTIONIt is believed that collecting ability and selectivity of collecting reagents is mainly governed by adsorption of a reagent at the solid–liquid interface. A few studies have shown that activity of collecting reagents at the gas–liquid interface may have deep influence on their collecting capacity and selectivity. Experimental researches have revealed correlation between surface pressure in a carboxylic acid film on liquid’s free surface and floatability of useful components (Kulkarni & Somasundaran, 1975; 1980; Quast, 2006). According to Quast (2006), it is not always that surface pressure of a reagent film influences collecting ability of carboxylic acid. For instance, pH range of adsorption of tetradecanoic acid on hematite does not coincide with pH range of high surface pressure. So, surface properties of this acid contribute little to flotation efficiency.The correlation between reagent film surface pressure and mineral floatability has been reveled for quartz and cationic reagents, too (Bleier, Goddard, & Kulkarni, 1977). Finch & Smith (1973) showed that combination of adsorption of ion–molecular amine complexes on mineral surface and high surface tension of “fresh bubbles” was favorable for flotation performance. The use of bubbles with reduced surface tension resulted in a decrease in quartz floatability."

Jan 1, 2016

By David S. Wong

With air emission limits for total particulates continually tightening, management of `potroom dust' or airborne particulates from aluminium smelting potrooms is of increasing importance. To better understand how settled and airborne particulates are generated within a potroom, methodologies have been developed to sample and analyse the compositional signature of dust, in relation to its sources. During a smelter case study, these methods allowed tracking of mineralogical phases in dust across a range of potroom locations, showing that the mechanisms of dust generation do vary spatially and vertically in a potroom. Such methodologies may also be applicable to other metallurgical industries.

Jan 1, 2011

By C. Rodgers, E. (Ted) Warren

"LocationThe Key Lake operation of Cameco Corporation is located at latitude 57°N in northern Saskatchewan, within the southem boundary of the Athabasca formation. The nearest city is LaRonge, located 240 km to the south. Access to the mine is by all-weather road and by private airstrip.Description of OperationThe mill was designed to produce twelve million pounds of uranium oxide (U3O8) a year from a feed grade of 2.4% U3O8. Current production is fourteen million pounds from 2.0% feed.Following grinding, the uranium is leached using sulphuric acid and oxygen in autoclaves. An eight thickener counter current decantation (CCD) circuit is used to separate the uranium-bearing solution from the solid waste residue. The uranium in solution is further purified in a solvent extraction circuit. The purified uranium is then precipitated using ammonia, calcined at 840°C, and packaged in drums for shipping to refineries. There is a crystallization circuit to recover excess ammonium sulphate produced in the process, and a waste treatment circuit.HistoryUranerz Exploration and Mining discovered the Gaertner and Deilmann orebodies in 1975 and 1976, respectively. Between 1975 and 1977, Uranerz conducted laboratory studies and delineated a process for the Key Lake ore known as the ""Bonn process."" In 1977, Sherritt Gordon Mines Ltd. was retained to conduct further studies in cooperation with U ranerz. The technical feasibility of the Bonn process was generally confirmed. Howeve1~ alternative processing methods also appeared feasible, and over the period 1978-1979, a detailed research and development program was conducted to finalize the processes to be used and to provide data for design of the plant."

Jan 1, 2000

By D. J. Farmer

Mining hoists are major components of any underground mine, however, the detailed design work required to get the actual power required for a particular hoist is outside the scope of preliminary feasibility studies. Nonetheless, a hoist is costly. Therefore, an accurate estimate is needed for the design parameters and the power required. There are two methods available, namely, the O’Hara method and the Society of Mining Engineers’ method. Tests were done for both methods employing nine friction hoists and 19 drum hoists currently in use at Canadian mines. The O’Hara method provided unacceptable results for both friction and drum hoists. While, the SME method was designed for American regulations and factors of safety which often differ significantly from Canadian ones, good results were obtained. The two relationships deter-mined were simply to add 5% to friction hoist design and to add 4% to drum hoist design. Modifying the SME method by these two factors will allow the hoisting system determined by the SME method to be within the error for a prefeasibility study.

Jan 1, 1997

By A. -M. Lafront

The corrosion resistance of die-cast and freely-solidified and electromagnetically-stirred thixocast AZ91D alloy has been studied using electrochemical noise technique in a 0.05M NaCI solution at pH 6.1 and 25°C. Specimens polished at different depths were immersed for a period of 75 min in order to assess the influence of the microstructure on corrosion kinetics and morphology. At depths between 10 and 50 µm (skin), all specimens showed general non-uniform corrosion with the lowest corrosion resistance. Between 100 and 200 µmn (interior skin), the observed corrosion was accompanied by superficial undefined pits due to metastable pitting. The corrosion form for 100-200 µm gave the best corrosion resistance. Stable pitting corrosion was observed beyond 400 µm deep on the bulk specimens. The skin of all thixocast specimens prepared billets showed a more corroded surface than that of die-cast. The interior skin as well as the bulk specimens showed better performance than that of the die-cast specimens.

Jan 1, 2007

By K. Huang, L. Pan

"Darcy’s law has been used extensively to model cake filtration. It is a macroscopic model, in which particle size dominates the kinetics and cake moisture. In the present work, a capillary flow model has been developed from first principles to study the effects of microscopic parameters such as capillary radius, boundary layer slip, disjoining pressure, and surface tension that may be important for dewatering ultrafine particles. Laboratory-scale pressure filtration tests show that dewatering kinetics is strongly dependent on capillary radius, which in turn is influenced by surface hydrophobicity, surface charge, and length scales of particles. The model parameters determined from laboratory-scale filtration tests show that use of a hydrophobizing reagent can greatly improve fine particle filtration due to increased slip and decreased capillary pressure. The kinetics of dewatering kaolin clay is fastest at a pH where the layer-structured particles coagulate with a face-to-edge orientation. The capillary flow model developed in the present work may be useful for designing filters and optimizing operating conditions.INTRODUCTIONIn 2014, Canada produced 2.2 million barrels per day of crude oil from the oil sands resources in Alberta, which is expected to grow to 3.2–4.0 million barrels per day by 2030 (CAPP, 2013). One of the challenges to meeting these projections is the tailings management. At present, the industry uses ?77 km2 of the lands to construct tailings ponds. Significant amounts of the tailings disposed to the ponds are silts and clays that are slow to settle and consolidate, creating problems for reclamation. It is, therefore, the objective of the present work to develop a filtration model that may be useful for developing advanced dewatering technologies that can address the tailings management issues.Darcy’s equation is the governing law for filtration. It was derived as an empirical model by H. Darcy in 1856 while he was studying fluid flow in sand filters (Hall, 1956). Since then, many investigators derived it from first principles. It relates superficial fluid velocity to the pressure drop across a porous medium of known permeability. In filtration, the latter can be related empirically to particle size using the Kozney equation (Yoon, 2005)."

Jan 1, 2016

By Hajime Miki, Gde Pandhe Wisnu Suyantara, Tsuyoshi Hirajima, A. M. Elmahdy, Keiko Sasaki

"Seawater has been reported to depress molybdenite in a copper-molybdenum (Cu-Mo) flotation process at high pH due to the precipitation of Mg(OH)2. Meanwhile, to improve mineral recoveries, collectors are usually added into the flotation cells, thus adding the complexity to the mechanism of bubble-particle interactions involved in Cu-Mo flotation. Therefore, understanding the interaction mechanism in seawater flotation and in the presence of collectors is important to explain the minerals depression. The present work investigated the effect of kerosene on the bubble collision and attachment to pure chalcopyrite and molybdenite surfaces in MgCl2 solution as one of the seawater major components at pH 6 and 11. Mineral surfaces were characterized using atomic force microscopy (AFM). In addition, minerals floatability in the same system were tested in a column flotation. The study of bubble-particle interactions shows that following several collisions, bubble could displace the intervening liquid layer on the mineral surfaces, forming a three-phase contact (TPC). A TPC formed more rapidly in the presence of emulsified kerosene in a 0.01 M MgCl2 solution at pH 6 for both minerals. The reason is kerosene increased the surfaces hydrophobicity and destabilized the intervening liquid layer on the surfaces. Moreover, the average time required to form a TPC was shorter on molybdenite surface. This can be attributed to the effect of adsorbed kerosene on molybdenite surface and molybdenite surface roughness.INTRODUCTIONIn froth flotation, bubbles are used to separate hydrophobic mineral particles from hydrophilic particles. In this process, bubble-particle interactions (i.e., collisions, attachment, and detachment) are crucial with regard to mineral recoveries. The effectiveness of froth flotation depends on the formation of stable aggregates between the hydrophobic particles and the bubbles, allowing the bubble to carry the particles to the froth layer. To form such aggregates, the bubbles and particles must collide, and the intervening liquid layer must be drained below the liquid layer critical thickness, forming a stable threephase contact (TPC) (Ralston & Dukhin, 1999). Particles detachment may take place if the particles still have sufficient kinetic energy and the TPC is not formed. Previous studies of bubble-particle interaction in electrolyte solutions have been conducted using atomic force microscopy (AFM) (Assemi, Nguyen, & Miller, 2008), and by approaching the bubble using mica plate (Pushkarova & Horn, 2008), however, these studies did not focus on the bubble-particle collisions. Bubble collisions and attachment to hydrophobic (Teflon) and hydrophilic (glass) surfaces in a a-terpineol solution have been investigated by Krasowka et al. (2003)."

Jan 1, 2016

By Sylvie Lévesque, Cory Hennessey, Daniel Amariei

"In the iron ore industry, fine particles recovery is an important concern in terms of process performance and production costs. Continuous efforts are thus devoted to increase the efficiency in handling these fines.The Reflux Classifier (RC) is a relatively new technology that is mainly used in the coal and industrial minerals industries. The operating principle of this system is based on three mechanisms: hindered settling, autogenous dense medium and lamella settling. A preliminary evaluation of the Reflux Classifier technology for the beneficiation of iron ore fines was formerly done at the pilot scale using a RCTM300 unit. The good results obtained, using iron ore fines from screened spiral stream, made this technology very attractive for the iron industry. However, the high capacity of the RCTM300 unit (1–3 t/h), makes it unsuitable for R&D purposes. Thus, a smaller unit, the RCTM100, was assessed to validate the performances obtained with the RCTM300.This paper summarizes the performances obtained with the RCTM100. The challenges of the scale-down related to the adaptability of this technology to the iron ore industry are also presented. The results are compared to the RCTM300 performances, as well as benchmarked against sink-float tests. The metallurgical results on feed and products issued after the test work with the RCTM100 unit are supported by mineralogical characterization using a Mineral Liberation Analyzer.INTRODUCTIONFine particles recovery by physical separation means is a historical concern (Holland-Batt, 1992; Peukert and Wadenpohl, 2001; Srivastavaa et al., 2001; Majumder et al., 2003). Attempts to improve fine particle recovery at the laboratory, pilot and industrial scales adopting different strategies with traditional equipment or assessing new promising devices such as the MGS (multi-gravity separator), the Kelsey jig, the Yang jig, etc. (Kim, 2002; Goudreau, 2008; Kerr, 2012) have yielded variable success."

Jan 1, 2016

By G. D. Markland

"The Moose Mountain mine is located in a belt of Precambrian volcanic rocks situated 20 miles north of Sudbury, Ontario. It was the first iron mining operation in the Archean iron-formations of the Canadian Shield.The ore is believed to have been formed in an environment of active volcanism, being part of a pyroclastic and volcanic series where only the iron-formation and chert qualify as chemical sediments. The volcanic environment, subsequent regional tectonics and metamorphism produced orebodies which differ from the main sedimentary iron ranges of the world in such features as continuity, grade, structure and metallurgical characteristics. The orebodies occur as relatively small lenses which have been complexly folded, faulted and intruded by acidic and basic dykesAlthough the basic mining and beneficiation methods are simple, detailed geological control in exploration, planning and operation has been necessary to apply detailed selective techniques to the large-scale open-pit methods necessary in profitable iron mining.The milling and pelletizing processes are sensitive to minor variations in ore grade, grain size, fabric and mineralogy. Although detailed correlations of geological information and mill performance are still not entirely satisfactory, general working relationships have been determined with simple testing procedures. These are of in-creasing use in forecasting production and in ore-blending processes.The application of geology to mining and milling operations at Moose Mountain represents a departure from general practice in iron ore operations."

Jan 1, 1966

By V. Bazhko, V. Yahorava

The calcium sulphate waste stream of the wet phosphoric acid process, commonly called phosphogypsum (PG), contains the majority of rare earth elements (REE) initially present in the apatite feedstock. Mainly light and middle REE are present in PG and their total concentration ranges from 0.27% to 0.35% by mass. Worldwide, around 7 billion tonnes of PG have been produced to date at a current growth rate of 150-200 million tonnes per annum. In total, an estimated 21 million tonnes of REE are locked in PG waste dumps around the world. Due to the value of the REE contained in PG dumps a number of processes have been devised for their recovery. The majority of these processes applied complete or partial gypsum dissolution, but were deemed not viable due to high capital and operating costs. Mintek developed an alternative method for the recovery of REE from PG by applying Resin-in-Leach (RIL) technology. This technology was tested on PG sampled from dumps and current arisings from South African phosphoric acid production plants. The extensive testwork program included evaluation of various lixiviants and optimisation of lixiviant additions, optimisation of REE leach and adsorption conditions, batch equilibrium and kinetic adsorption tests, continuous RIL testwork and numerous variability tests. It was found that PG from different sources was highly variable, both in terms of REE recovery as well as physical properties of the material such as viscosity and filterability of the slurry. The recovery of REE varied from 15% to 80% depending on the origin of the samples. A high-level economic study indicated that at a price of >21 $/kg for mixed REE oxide product in conjunction with an overall REE recovery as low as 15% the economics of REE recovery from PG via RIL technology may already be favourable.

Jan 1, 2016

By G. D. Markland

The Moose Mountain mine is located in a belt of Precambrian volcanic rocks situated 20 miles north of Sudbury, Ontario. It was the first iron mining operation in the Archean iron-formations of the Canadian Shield. The ore is believed to have been formed in an environment of active volcanism, being part of a pyroclastic and volcanic series where only the iron-formation and chert qualify as chemical sediments. The volcanic environment, subsequent regional tectonics and metamorphism produced orebodies which differ from the main sedimentary iron ranges of the world in such features as continuity, grade, structure and metallurgical characteristics. The orebodies occur as relatively small lenses which have been complexly folded, faulted and intruded by acidic and basic dykes.

Feb 1, 1966

By T. W. Wlodek, Zygmunt Kowalczyk

In the period from 1946 to 1964, the annual output of co al from Polish mines increased from 4 7.3 to 117.35 million tons. In this paper, the methods of bringing about this increase in productivity through the building of some twelve new collieries (producing some 15 million tons annually) and the modernization, reconstruction and extension of some thirty-six older collieries are discussed.

Jan 1, 1967

By Y. Wang

In this paper, the tribological and electrochemical corrosion properties of Al2O3/polymer nanocomposite coatings were studied using a micro-hardness test, a single-pass scratch test, an abrasive-wear test, and finally an electrochemical technique such as potentiodynamic polarization measurement, The coatings containing Al2O3 nanoparticles showed improvement in scratch and abrasive resistance compared with polymer coatings; this improvement is attributed to the dispersion hardening of Al2O3 nanoparticles in polymer coatings, Corrosion test results showed that the embedded Al2O3 nanoparticles in the polymer matrix do not sacrifice the corrosion resistance of the polymer itself.

Jan 1, 2005

By D. R. Reeves

This paper describes the geophysical Jogging of coal that is being carried out for the National Coal Board in the United Kingdom. An explanation of the technique is given and results are presented showing estimations of seam thickness to within ±0.5 in. and ash content to accuracies of ±2.5 per cent. The basic method of interpretation is outlined and some conclusions regarding the conditions of roof and floor material which may be deduced from the logs are explained. An indication of future developments in this field, including the identification of coal type and moisture content, is given.

Jan 1, 1971

By R. Argane

In this work we assessed the geochemical behavior of concentrator tailings deposited at the abandoned mines of Zeida and Mibladen (Upper Moulouya, Morocco), using physico-chemical analyses, mineralogical characterization, acid base accounting and weathering cell tests. The aim of the study was to evaluate mine drainage quality and to assess metal mobility from these concentrator tailings. Chemical analyses show that the Upper-Moulouya abandoned tailings contain relatively high quantities of lead (0.261 to 0.594 % wt). Mineralogical analyses reveal the abundance of neutralizing minerals (calcite, dolomite, ankerite, and aluminosilicates) which influence mine drainage and metal mobility in mine tailings. Leachate analyses from weathering cell tests show alkaline conditions, small conductivity values, and low solubility of Pb-mineral phases. According to these results, abandoned mine tailings in the Upper-Moulouya district have very low potential for generation of contaminated mine drainage and for leaching of heavy metals. However, the inhalation of tailings exposed to winds generate dust problem facing the local population and may cause health consequences.

Aug 1, 2013