Occurrence Of Zinc Research Articles

Resource potential of the Proterozoic–Paleozoic Carrara depocentre, South Nicholson region, Australia: Insights from stratigraphic drilling

A comprehensive geochemical program was carried out on rock samples collected in the NDI Carrara 1 drill hole, the first stratigraphic test of the newly discovered Carrara Sub-basin located in the South Nicholson region of northern Australia. The drill hole recovered continuous core from 284 m to total depth at 1750 m and intersected approximately 1120 m of Proterozoic sedimentary rocks, unconformably overlain by 630 m of Cambrian Georgina Basin carbonate-rich rocks. Total organic carbon (TOC) contents from Rock-Eval pyrolysis highlight the potential for several thick black shales to be a source of petroleum for conventional and unconventional plays. Cambrian rocks contain an organic-rich section with TOC contents of up to 4.7 wt.% and excellent oil-generating potential. The Proterozoic section is overmature for oil generation but mature for gas generation, with potential for generating gas in carbonaceous mudstones showing TOC contents up to 5.5 wt.% between 680 and 725 m depth. A sustained release of methane (up to 2%) recorded during drilling from 1150 to 1500 m suggests potential for an unconventional gas system in the Proterozoic rocks from 950 to 1415 m depth, which exhibit favourable organic richness and thermal maturity. The Proterozoic rocks, which are comparable in age to the sediment-hosted deposits of the Century Mine, contain local occurrences of lead, zinc and copper sulfide minerals providing hints of mineralisation. The combined geochemical results offer the promise of a potential new resource province in northern Australia.

Boron-bearing skarn-magnetite mineralization of the Mingbulak ore field, Eastern Uzbekistan

Spatial distribution of skarn-magnetite deposits in the Tien Shan region is closely related to gabbroid magmatism that accompanies wide fault zones bordering the South Tien Shan folded system from the north and south and extending as a latitudinal belt towards the Middle and Southwestern Tien Shan.Studies fulfilled during recent decades in the Karzhantau Ridge area have quite clearly demonstrated its gold-copper-bismuth metallogenic specialization with the leading role of gold. The most promising position is characteristic of the Aktash group ore occurrences (Aktam-I, Aktam-II, and Yuzhnoe).Within the studied Mingbulak area of Karzhantau, the most widely distributed are mineral occurrences of iron ore, lead and zinc, gold, and copper, and less developed boron-bearing, tungsten, and fluorite ones. Most of the mineral occurrences in the area formed as a result of magmatic-hydrothermal activity and are confined to fault zones characterized by long duration and complexity of the formation. The mineralization is usually localized in the crush zones and feathering fractures of the faults. The skarn type includes ore occurrences of iron, a metal that is currently strongly deficient for mining enterprises in the Tashkent region.

Quantifying spatial variability of available zinc in alluvial soils of Brahmaputra plains, India

Occurrence of zinc (Zn) deficiency in soils and plants has been accounted for worldwide including northeastern India. The present study was conducted to determine the spatial distribution and degree of risk of Zn deficiency in Brahmaputra plains of northeastern India using statistics and geostatistics. With the help of handheld global positioning system (GPS), 5494 soil samples were collected using 1 km x 1 km grid at 0–25 cm depth from three districts of Assam state of India namely, Tinsukia, Morigaon and Nalbari representing upper Brahmaputra valley zone (UBVZ), central Brahmaputra valley zone (CBVZ) and lower Brahmaputra valley zone (LBVZ) covering 6249 km2 area and analyzed for pH, organic carbon (OC) and Zn. Dataset was normally distributed. Geo statistical analyses were carried out, including experimental variogram and model fitting. Analysis of the isotropic variograms indicates that the range values of 3900, 4400 and 5800 m for UBVZ, CBVZ and LBVZ, respectively. It implies that the length of the spatial autocorrelation was much longer than the sampling interval of 1 km. The nugget/sill ratio was 0.506, 0.859 and 0.589 for UBVZ, CBVZ and LBVZ, respectively and it indicates moderate spatial dependence. Further, with the ordinary kriging, spatial distribution map showed that the Zn is deficient for plants in the all the three zones of Brahmaputra plains. The probability map produced based on indicator kriging showed that Zn deficiency was noticed in 34% of crops grown area of the Tinsukia, 70% crops grown area in Morigaon and 85% of crops grown area in Nalbari districts. The correlation analysis showed that Zn was significantly and positively correlated with OC and significantly and negatively with pH in Brahmaputra plains. Thus, the present study is of immense help to minimize both yield loss and environmental threats of Zn toxicity due to under or overdose of Zn fertilizer application in Brahmaputra plains of northeastern India.

Occurrence, Origin and Risk Assessment of Trace Metals Measured in Petroleum Tank-farm Impacted Soils

ABSTRACT The objective of this study was to determine the occurrence, origin, and risk of Cadmium (Cd), lead (Pb), chromium (Cr), nickel (Ni), copper (Cu), manganese (Mn), zinc (Zn), and iron (Fe) in soil profiles from petroleum tank-farms in Western Delta, Nigeria. The soil samples were digested with aqua-regia, and the concentrations of the metals were determined using an atomic absorption spectrophotometry. The mean concentrations of metals varied for all sites and depths and ranged from 1.86 ± 1.73 mg kg−1 (Cd) to 3535 ± 1802 mg kg−1 (Fe). The mean concentrations of Cd, Pb, and Cu exceeded the Dutch and DPR-EGASPIN target limits in 80%, 5%, and 45% of the samples, respectively. Concerning soil depths, the metals showed irregular occurrence and exhibited concentration load in the order of subsoil > bottom soil > topsoil. The results also showed that the metals had the highest concentrations at site SS1, SS2, SS4, SS6, SS8, SS9, SS10, and SS11. The linear regression between TOC and metals indicates a weak correlation. The ANOVA shows that there is a significant variation for the total concentrations of the metals concerning soil depths. The PCA, enrichment factors and the geo-accumulation index suggest that the trace metals originated from the anthropogenic and geologic means. The average contamination factor and the ecological risk factor followed the order: Cd > Pb > Cu > Zn > Mn > Cr > Ni, and Cd > Pb > Cu > Ni > Zn > Cr > Mn, respectively. The non-carcinogenic risk shows no adverse non-carcinogenic health effects for human exposure to metals. The total cancer risk values are within acceptable safety limits. The results of the heavy metals from this study suggest that soils from the petroleum tank farms require sustainable remediation measures.

Synthesis, structure, polyphenol oxidase mimicking and bactericidal activity of a zinc-schiff base complex

Focusing on the important biological functions of metallo-enzymes and metallo-therapeutics in living world, this research work demonstrates the synthesis, crystal structure, supramolecular architecture, 4-methylcatechol oxidation and bactericidal activity of an interesting zinc-Schiff base complex, [Zn(HL)2Cl2] (1), [Schiff base (HL) = 2-(2-methoxybenzylideneamino)phenol]. Crystal structure analysis of the zinc-Schiff base reveals that zinc centre exists in a distorted tetrahedral geometry. The Schiff base adopts three donor centres, however it gets protonated to exist in a zwitter ionic form and behaves as a monodentate coordinator in 1. This zinc-Schiff base complex has been examined towards the bio-mimetic oxidation of 4-methylcatechol (4-MC) in methanol and portrays its good efficacy with good turnover number, 1.45 × 103 h−1. Electro-chemical study, electron paramagnetic resonance analysis and electrospray ionization mass spectrometry results for the zinc-Schiff base complex in presence of 4-MC ensures that the catalytic reaction undergoes through enzyme-substrate binding, and generation of radical in the course of catalysis drives the catalytic oxidation of 4-MC. Antibacterial study has also been performed against few clinical pathogens (Bacillus SP, Enterococcus, and E. coli). Scanning electron microscope and EDAX analysis for the pathogen with little dose of zinc complex confirms the destruction of bacterial cell membrane with 1.44% occurrence of zinc in the selected zone of inhibition area. This observation holds a great promise to develop future antibacterial agent.

Inorganic pollutants in the indoor environment of the Moravian Library: assessment of Cd, Pb, Cu, and Zn in total suspended particles and dust using HR-CS GF-AAS.

In this study, the occurrence of lead (Pb), cadmium (Cd), copper (Cu), and zinc (Zn) in the environment of the Moravian Library in Brno, the second largest library in Czechia, was in focus. The materials of interest were airborne particles, dust originating from books, and also book pages. Total suspended particles (TSP) were sampled in different areas of the library, including the reading room, the book depository, and an external book warehouse. Samples of dusts were obtained from the book-cleaning system, and, moreover, some pages taken from old books were also analyzed. Samples were microwave-digested and analyzed using graphite furnace high-resolution continuum source AAS (HR-CS GF-AAS). During the analysis, possibilities of the signal intensity modulation of the HR-CS technique were demonstrated and employed in order to determine Zn, an element which is rarely determined by GF-AAS. The median TSP concentrations (in ng/m3) were as follows: Pb, 4.4; Cd, 0.07; Cu, 2.6; and Zn, 20.9. Such concentrations are safely below allowed limits. Contents of Pb determined in dust samples and book pages were slightly higher (up to 707 and 38 mg/kg, respectively) than the usually reported values. However, none of these results indicate a potential risk to library staff or readers.

Contribution of crustal and mantle sources to genesis of Sn, B and Pb-Zn deposits in South Sikhote-Alin subprovince (Russian Far East): Evidence from high–precision MC-ICP-MS lead isotope study

South Sikhote-Alin metallogenic subprovince (SSAP) is located in the southern part of the Sikhote-Alin orogenic belt. It encompasses more than one hundred well-known deposits and occurrences of boron, tin, lead, and zinc. These deposits have been genetically related to the Late Cretaceous and Paleocene granitoid magmatism. Pb isotope composition was measured using the MC-ICP-MS method in 20 SSAP deposits. Pb isotope ratios (48 samples of galena) vary within narrow limits: 206Pb/204Pb ranges from 18.321 to 18.474, 207Pb/204Pb − 15.608–15.655, and 208Pb/204Pb 38.601–38.796. The high degree of homogeneity of the Pb isotope composition and absence of correlations between the lead isotope characteristics of the deposits, on the one hand, and the age and type of ore mineralization, on the other, indicate the presence of a regional uniform Pb source for all the SSAP deposits. The results of Pb-Pb studies of the different rocks of the SSAP suggest that the source was most likely the Mesozoic sedimentary sequences of the Sikhote-Alin accretionary complexes. In turn, individual lead isotope characteristics of the SSAP deposits are caused by varibale contribution of mantle source to the overall balance of lead.

Acute and Chronic Effects on Tadpoles (Lithobates catesbeianus) Exposed to Mining Tailings from the Dam Rupture in Mariana, MG (Brazil)

The mining sector has great importance to the economic activity in Brazil. However, it is also responsible for several environmental impacts such as the rupture of the Fundao dam (Mariana, Brazil) that resulted in the spillage of 50 million m3 of mining tailings in the Doce River Basin. This study evaluated the acute and chronic effects of Fundao tailings on growth, development, respiration rates, swimming performance, and avoidance behavior of Lithobates catesbeianus tadpoles. Results showed that 96-h exposure to different dilutions (10, 25, 50, 75, and 100%) of a stock solution containing mining tailings (50 g/L) caused no mortality of tadpoles; however, the most concentrated solution decreased the swimming speed of the animals. After 16 days, tadpoles exposed to 25, 50, and 100% treatments had both swimming speed and distance traveled reduced. Oxygen consumption was also decreased in tadpoles exposed to the 100% solution after 20 days. Avoidance test indicated that tadpoles avoided lower tailing concentrations, but a reduced avoidance response was attested to the higher concentrations, probably due to the toxic effects of the residues that prevented animals’ displacement. Chemical analysis confirmed the occurrence of cadmium (Cd), lead (Pb), iron (Fe), manganese (Mn), zinc (Zn), and aluminum (Al) in Fundao tailings and its presence in the mouth and inside the intestine of treated tadpoles indicated the ingestion of metals by these organisms. This study showed that even presenting low lethal toxicity, long-term exposure to mining tailings from Fundao dam caused morphophysiological and behavioral damage in tadpoles.

Coal Mine Water Drainage: The Current Status and Challenges

Any form of mining is a potential threat to the environment. The extent of environmental degradation depends on the status of mine (working/abandoned), type of deposit, mining and processing methods and the geo-atmospheric conditions. Coal mining has huge impacts to local water resources, both surface and ground water. Surface waters are being contaminated through the discharge of mine water, which is also called mine drainage. Ground water is being contaminated due to pilfer of the aquifers. Coal mine drainage is found heavily acidic throughout the world. High acidic water also poses to contaminate with toxic heavy metal ions. Heavy metal pollution comprises the trace occurrences of elements, namely, arsenic, lead, cadmium, cobalt, copper and zinc, coming from the host rock on its exposure to mine drainage water in acidic environment. As the mine water flows over the host rock, metals are leached into the water and mix with the surface waterbodies. These chemicals can be highly toxic to humans and wildlife. Though the heavy metals can dissolve in mine drainage even in non-acidic pH conditions also, but leaching is increased manifold in the acidic environment. From underground coal mines, million liters of mine water is daily disposed to the natural water sources, which are commonly used by the local inhabitants. Most of the Indian coal mines are not generating acidic drainage due to dearth of pyrites in the seams. Thus, it is a common belief that Indian coal mine drainage does not need treatment for heavy metals and is directly discharged into the surface streams. This present study shows that despite the non-acidic mine drainage, Indian coal mine water comprises high heavy metal contaminants and demands immediate attention. It is also revealed that Indian coal mine drainage shows neutral/slightly alkaline water despite having significant iron content.

Occurrence of Trace Metals in Food Crops Grown on the Mbale Dumpsite, Uganda, and Human Health Risks.

Food crops can be used as biomonitors to assess potential public health food safety hazards from contaminated agricultural environments. Globally, more than 800 million people grow fruits, vegetables, and grains on urban garden soils with unknown health risks. This worldwide practice has exposed consumers to pathogenic and carcinogenic risks from locally grown and imported contaminated foodstuffs such as Amaranthus cruentus and Zea mays, traditional and widely consumed crops across the globe. This study used Z. mays and A. cruentus crops to investigate the occurrence and spatial variations of aluminum (Al), chromium (Cr), iron (Fe), manganese (Mn), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), arsenic (As), selenium (Se), cadmium (Cd), mercury (Hg), and lead (Pb) concentrations across the Mbale dumpsite, Uganda. Mean concentrations for Fe, Al, Zn, Mn, and Cu were high in both crops, whereas Pb, Cr, Co, Cd, As, Hg, Se, and Ni occurred in trace amounts. Using the 2 crops as biomonitors, significant variations for Al, Zn, Fe, Cr, and Co concentrations in individual crops were identified across the dump center, hill slope, and riverbank. The variations in Al, Zn, Fe, Cr, and Co concentrations were specific for crop types, crop parts, and location. The highest overall accumulation of metals was at the dump center and in crop leaves. Except Pb concentrations in Z. mays seeds, Cr, Pb, Zn, and Al concentrations in other crop parts were above World Health Organization/Food and Agricultural Organization consumer food safety limits. Therefore, Z. mays and A. cruentus consumption could pose health risks to consumers. Further health assessments and potential regulations are recommended to reduce potential health risks from metals in crops for human consumption. Integr Environ Assess Manag 2020;16:362-377. © 2019 SETAC.

Quantification of Metal Contaminants and Risk Assessment in Some Urban Watersheds

Contamination by heavy metals is a serious threat to aquatic systems due to their level of toxicity at elevated levels. The pollution of urban watersheds is of particular concern because of its potential impact on the watershed ecosystem and the receiving larger water bodies. This study assessed the occurrence and distribution of cadmium, copper, nickel, lead and zinc in water and sediment samples collected from three urban watersheds in Lagos, Nigeria. The concentrations of metals were determined using atomic absorption spectrometry. The health risk index (HRI) of water usage was evaluated for both adults and children. HRI for cadmium and lead in some of the watersheds recorded HRI > 1 values, a cause for health concern. The pH of water ranged from 6.48 ± 0.28 - 6.54 ± 0.47 (2016) and 6.18 ± 0.56 - 6.53 ± 0.17 (2018) respectively while, for sediments, the pH values ranged from 6.14 ± 0.48 - 6.9 ± 0.15 and 5.38 ± 0.22 - 6.4 ± 0.38 for 2016 and 2018 respectively. The levels of metals in the water samples during the 2016 sampling cycle were found to be within the World Health Organization (WHO) guideline limits for drinking water. However, the 2018 cadmium, lead and zinc concentrations for Ira-Ipaye and Akesan watersheds exceed the WHO guideline limits. Cadmium was not detected in Ira-Ipaye and Akesan 2016 sediment samples. Statistical t-test and analysis of variance (ANOVA) were used to ascertain significant differences of metals concentration in the three watersheds. The pH and metal concentration values obtained for water and sediment for the year 2016 and 2018 were non-significantly different.

Factors influencing the occurrence of Zinc Induced Cracking in square steel pipe

Factors influencing the occurrence of Zinc Induced Cracking in square steel pipe

Effect of steelmaking dust characteristics on suitable recycling process determining: Ferrochrome converter (CRC) and electric arc furnace (EAF) dusts

Utilization of dusts generated from steelmaking industries will avoid disposal of wastes, enhance the use of secondary raw material fines and save costs. Understanding the properties of dust is necessary before determining the suitable recycling method. The present paper describes the chemical, morphological and mineralogical characterization of steelmaking dusts produced in steel plants in Finland. In this paper three different steelmaking dusts: ferrochrome converter (CRC) and electric arc furnace stainless steel (EAFSS) dusts from Outokumpu (Tornio, Finland), and electric arc furnace carbon steel (EAFCS) dust from Ovako (Imatra, Finland) were characterized.The characterization study showed that, the dusts from carbon steelmaking (EAFCS) are rich in zinc, while the dusts from stainless steelmaking (CRC) and (EAFSS) are relatively low in zinc, but richer in chromium. The zinc contents in CRC, EAFSS and EAFCS dusts are 10.83, 19.84 and 35.76wt%, respectively, while the chromium contents are 20.88, 3.19 and 0.47wt%, respectively. In the dust from CRC, zinc is found as zinc oxide (zincite, ZnO), while in the dusts from EAFSS & EAFCS zinc is found mostly as zinc ferrite (franklinite, ZnFe2O4). Scanning electron microscopy (SEM) investigations indicated that CRC dust is dominated by non-spherical form and composed mainly of aggregates of irregular particles of chromite, in addition to zincite sphere. EAFSS dust particles are characterized by encapsulation phenomenon, franklinite particles enclosed inside calcium-iron-silicate glass sphere. Manganese (Mn) concentrations show positive correlation with Zn, which suggests the occurrence of Mn mainly with franklinite phase. EAFCS dust is dominated by spherical form, and zinc found as franklinite and zincite. In the large particles >3μm of EAFCS dust, franklinite enclosed inside glass sphere, while in finer particles <1μm, both zincite and franklinite existed as spheres.The investigations indicate that steelmaking dusts from CRC, EAFSS, and EAFCS show significant difference in concentration and mode of occurrence of zinc in the dusts, which will influence the determination of suitable processing methods.

Effect of compressive plastic strain on the occurrence of Zinc Induced Cracking

Effect of compressive plastic strain on the occurrence of Zinc Induced Cracking

Concentration and mobility of copper and zinc in the hypergenic zone of a highly urbanized area

Common occurrence of copper and zinc in groundwater and their diverse mobility in the environment make these metals sensitive indicators of industrial and municipal pollution of freshwaters. An analysis of the collected data allowed for a description of the factors and processes that induce changes in the concentration of these metals in the soil, rock and groundwater. Sorption, ion exchange and oxidation–reduction processes, dissolution and precipitation of minerals, and reactions involving organic matter significantly affected the mobility of copper and zinc. The study employed hydrogeochemical methods to obtain comprehensive interpretative data. Its results showed that the variability of the composition of exchangeable cations was due to instability of chemical composition of precipitation. Different activities of Cu and Zn in the solution introduced into the rocks led to the establishment of new quasi-equilibrium states between the adsorbent and the adsorbate. At very low copper and zinc concentrations in groundwater, zinc was more easily retained in the solid phase, and it was more difficult to extract. In contrast, a laboratory static batch experiment utilizing high concentrations of the elements in the solutions showed their different behavior. The sorption of copper occurred more easily than the sorption of zinc, as evidenced by the study results and the calculated parameters of sorption maximum, binding constant, and degree of surface coverage of the solid phase by adsorbed copper and zinc according to a single Langmuir equation.

Actinobacteria occurrence and their metabolic characteristics in the nickel-contaminated soil sample

AbstractHeavy metals are a significant source of pollution in soils that have been demonstrated to exert significant toxic effect on soil microbial assemblages. Here we investigate the occurrence and metabolic characteristics of actinobacteria, which form a predominated component of farmland bacterial community near the town of Sereď in southwest Slovakia, contaminated by close nickel ore facility. Actinobacteria occurred in this environment with high concentrations of nickel (2.109 mg/kg), slightly above the natural occurrence of cobalt (355 mg/kg) and zinc (177 mg/kg), even too low concentration of iron (35.75 mg/kg) for a normal soil and not a toxic amount of copper (32.2 mg/kg) and cadmium (&lt;0.25 mg/kg). The phylogeny was reconstructed using partial sequences of 16S rDNA genes of both, actinobacterial isolates and clones. A total of 105 actinobacterial representatives were divided into 66 species belonging to one order, 7 genera and 5 uncategorized groups. The selected 14 morphologically distinct isolates were able to produce drop collapsing, haemolytic and lipase activities. Whereas only 4 isolates produced dark brown melanin pigment and only 5 of them produced decolourization of the azo dye, all isolates tested were capable of assimilating all 11 sugars tested. All these actinobacterial isolates were resistant to nickel, cobalt, zinc, cadmium, copper, but the level of resistance differed between the individual isolates, and the resistance profiles of antibiotics (gentamycin, ampicillin, ciprofloxacin, chloramphenicol, erythromycin, rifampicin, penicillin-G) varied among them to a certain extent. Our results suggested that actinobacteria in soil contaminated by nickel present a relatively divergent group inside of microbial assemblage.

Integrating 3D photogeology with aeromagnetic data as a tool for base-metal exploration in East Greenland

An 800 km long basin system developed along the East Greenland margin since the Late Palaeozoic in which the Jameson Land Basin forms the southern part of the system. Along the margins of the Jameson Land Basin there are occurrences of barite, copper, lead, zinc and silver, which are particularly abundant in the northern part of the basin’s eastern margin in the Wegener Halvø area (Fig. 1). Structures and stratigraphic architecture play important roles in the mineralisation distribution, so detailed mapping is essential. We used 3D photogeology combined with geophysical data to map the different stratigraphic units, faults and dykes in three dimensions.

3D Inversion of magnetic data of grouped anomalies — Study applied to São José intrusions in Mato Grosso, Brazil

The southwest border of the Parecis Basin (central Brazil) presents several occurrences of gold, copper and zinc. Parallel to this border, there is an alignment of magnetic anomalies with varied size and polarities. In particular, five magnetic anomalies are referred to, in this study, as SJ1 to SJ5. The proximity of these anomalies to each other makes it hard to isolate the magnetic component associated with each source. Furthermore, these anomalies have different magnetization directions, which require the use of a technique which is slightly or not affected by the presence of a remanent magnetization, as the amplitude of the anomalous magnetic field. Considering that, in these intrusions no outcrops are observed, the enhanced horizontal derivative technique was used to estimate the edges location and the depth of these sources. The geological context, allied to the results from the magnetic techniques, allowed to establish binds to restrain the interpretation of the results of the 3D inversion. This procedure permitted to compose three hypothesis to explain the magnetic behavior of the region, from which can be conclusively determined with a borehole analysis.

Assessment of Heavy Metal Contamination in Paddy Soils from Daye Mining Area of Hubei Province, China

The occurrence and distribution of heavy metals (including copper (Cu), lead (Pb), zinc (Zn), cadmium (Cd), chromium (Cr), cobalt (Co), nickel (Ni) and manganese (Mn)) in paddy soils from the Daye mining area were investigated by atomic absorption spectrophotometry (AAS) using the flame and graphite furnace method. The pollution of all metals investigated was found in paddy soil samples from the Daye mining area. Additionally, Cu, Pb, Zn and Cd concentrations at the sampling sites near the quarries and mines located in the central and eastern part of Daye were higher than those at the other sampling sites. Hierarchical cluster analysis and principal component analysis (PCA) of the heavy metal concentrations showed that the mine might be an important contributor to heavy metals contamination. PCA analysis extracted two factors that explained 67% of the total variables. The source of Zn, Cd, Cu and Pb would be primarily the deposition of aerosol particles emitted by metal smelting, manufacturing and traffic, acid mine drainage and metal mine waste rock and long-term stockpiling of tailings. Ni and Cr were controlled by parent material in the soils. Evaluation of heavy metals contamination of paddy soils indicated that the Cd contamination was the most widespread, followed Cu, Ni, Zn and Pb.

Removal of magnesium from sphalerite concentrates by means of spent electrolyte deriving from the process of cathode zinc extraction

Streszczenie Występowanie złóż rud cynku i ołowiu w skałach dolomitowych sprawia, że otrzymane koncentraty sfa-lerytowe zawierają domieszkę dolomitu. Praktyka wskazuje, że znaczna część wprowadzanego magnezu z su­rowcami cynkowymi przechodzi do ostatniej fazy produkcji, elektrolizy cynku. Obecność magnezu w elektrolicie obniża przewodnictwo elektryczne elektrolitu i powoduje pogorszenie wskaźników techniczno-ekonomicznych. Celem opisanych w tym artykule badań było opracowanie metody usuwania magnezu z surowego koncentratu sfalerytowego na drodze chemiczno-flotacyjnej, stosując zużyty elektrolit pochodzący z elektrolizy cynku. Opracowanie ukierunkowano wokół doświadczalnego zobrazowania istniejących zależności i ustalenia opty­malnych warunków zaproponowanej procedury. Stopień wyługowania magnezu wynosił około 80%. Straty cynku wynosiły poniżej 2%, natomiast stężenie magnezu w roztworze wynosiło 20%. Z tych roztworów można odzys­kiwać magnez i cynk, co będzie przedstawione w następnej publikacji.